541088 Workbook Pneumatics Basic Level

Pneumatics Basic level

Workbook TP 101

With CD-ROM

1A1

1B1

1Z1

1Z2

1

1V3

1

2 1V2

2

4

2

5

3

14

1V1 1

1

12

2 1

1

3

2

1S1

2

1V4

1

1B1

3

1

2

2

1S2

3

1

3

Festo Didactic 541088 en

Use for intended purpose The training system from Festo Didactic has been developed and manufactured for training and vocational education in the field of automation technology. The respective training companies and/or trainers must ensure that all trainees observe the safety precautions which are described in this workbook. Festo Didactic hereby excludes any and all liability for damages suffered by trainees, the training company and/or any third parties, which occur during use of the equipment sets in situations which serve any purpose other than training and/or vocational education, unless such damages have been caused by Festo Didactic due to malicious intent or gross negligence.

Order no. Status: Authors: Editor: Graphics: Layout:

541088 03/2012 W. Haring, M. Metzger, R.-C. Weber Frank Ebel Doris Schwarzenberger 03/2012

© Festo Didactic GmbH & Co. KG, D-73770 Denkendorf, Germany, 2013 Internet: www.festo-didactic.com E-mail: [email protected]

The purchaser shall receive a single right of use which is non-exclusive, non-time-limited and limited geographically to use at the purchaser's site/location as follows. The purchaser shall be entitled to use the work to train his/her staff at the purchaser's site/location and shall also be entitled to use parts of the copyright material as the basis for the production of his/her own training documentation for the training of his/her staff at the purchaser's site/location with acknowledgement of source and to make copies for this purpose. In the case of schools/technical colleges and training centres, the right of use shall also include use by school and college students and trainees at the purchaser's site/location for teaching purposes. The right of use shall in all cases exclude the right to publish the copyright material or to make this available for use on intranet, Internet and LMS platforms and databases such as Moodle, which allow access by a wide variety of users, including those outside of the purchaser's site/location. Entitlement to other rights relating to reproductions, copies, adaptations, translations, microfilming and transfer to and storage and processing in electronic systems, no matter whether in whole or in part, shall require the prior consent of Festo Didactic GmbH & Co. KG.

Table of contents Preface _________________________________________________________________________________ V Introduction ____________________________________________________________________________ VII Technology module for pneumatics (TP100) ____________________________________________________X Learning objectives for the basic level (TP101) _________________________________________________ XI Overview of learning objectives per exercise __________________________________________________ XII Equipment set for the basic level (TP101) ____________________________________________________ XIV Allocation of equipment per exercise _______________________________________________________ XVIII Practical tools for the trainer _______________________________________________________________ XIX Structure of the exercises _________________________________________________________________ XIX Designations of the components____________________________________________________________ XIX CD ROM contents ________________________________________________________________________ XX Equipment set for the advanced level (TP102) ________________________________________________ XXII Learning objectives for the advanced level (TP102)____________________________________________ XXIII

Solutions Exercise 1: Pressing cheeses _________________________________________________________________1 Exercise 2: Opening a fodder silo _____________________________________________________________9 Exercise 3: Clamping boards to a saw bench __________________________________________________ 15 Exercise 4: Sorting packages _______________________________________________________________ 21 Exercise 5: Stopping milk bottles ___________________________________________________________ 31 Exercise 6: Opening and closing a pipeline ___________________________________________________ 37 Exercise 7: Shutting off a pipeline ___________________________________________________________ 45 Exercise 8: Actuating a shut-off device _______________________________________________________ 51 Exercise 9: Expanding the control system for pressing cheeses ___________________________________ 59 Exercise 10: Clamping a workpiece __________________________________________________________ 65 Exercise 11: Loading wire baskets __________________________________________________________ 73 Exercise 12: Actuating a sliding door ________________________________________________________ 79 Exercise 13: Feeding wooden boards ________________________________________________________ 87 Exercise 14: Compacting beverage cans ______________________________________________________ 93 Exercise 15: Packaging of brochures ________________________________________________________ 99 Exercise 16: Mounting locking pins_________________________________________________________ 105 Exercise 17: Labelling paint pots___________________________________________________________ 111 Exercise 18: Cleaning workpieces __________________________________________________________ 117 Exercise 19: Pressing labels into place ______________________________________________________ 123

© Festo Didactic GmbH & Co. KG 541088

III

IV


Preface Festo Didactic’s training system for automation and technology is geared towards various educational backgrounds and vocational requirements. The training packages are therefore broken down as follows:  Basic modules impart basic, interdisciplinary, technological knowledge.  Technology modules address the important topics of open and closed-loop control technology.  Function modules explain the fundamental functions of automated systems.  Application modules enable training and further education that is aligned with real-life practice. The technology modules deal with various technologies including pneumatics, electro-pneumatics, programmable logic control systems, automation using a personal computer, hydraulics, electrohydraulics, proportional hydraulics, sensor technology, electric drives and applications technology (handling).


V

The modular design of the training system makes it possible to focus on applications above and beyond those covered in the individual modules, such as, for example, PLC actuation of pneumatic, hydraulic and electric drives. All training modules have the same structure:  Hardware  Teachware  Software  Seminars The hardware is comprised of industrial components and systems that are specially designed for training purposes. The structure of the teachware corresponds to that of the training hardware. It includes:  Textbooks (with exercises and examples)  Workbooks (with practical exercises, supplementary instructions and solutions)  Transparencies and videos (for dynamic instruction) The working materials for TP101 consist of 19 exercises and a workbook. Each exercise has its own set of ready-to-use worksheets. The solutions are included in the workbook, which also has the worksheets and a CD ROM. The exercises can be purchased without the workbook and are used as consumables. They can thus be easily made available to trainees. Data sheets for the hardware components are made available along with the training module and on the CD ROM. The teaching and learning media are available in several languages. They’re intended for use in classroom instruction, but are also suitable for self-study. Where software is concerned, computer training programs and programming software are made available for programmable logic controllers. A wide range of seminars covering the contents of the technology module round off the programme for training and further education.

VI


Introduction This workbook is part of the training system for automation and technology from Festo Didactic GmbH & Co. KG. The system provides a solid basis for practical training and further education. The TP100 technology module only includes pneumatic control systems. The TP101 basic level is suitable for basic training in the field of pneumatic control technology. It covers the fundamentals of pneumatics as well as the function and use of pneumatic equipment. The equipment can be used to set up simple pneumatic control systems. The TP102 advanced level comprises vocational training in the field of pneumatic control technology. The equipment can be used to set up extensive combinatory circuits with linking of the input and output signals as well as control systems with stepper modules. A permanent workstation equipped with a Festo Didactic profile plate is a prerequisite for setting up the control systems. The profile plate has 14 parallel T-slots at 50 mm intervals. A portable compressor with silencer (230 V, max. 8 bar = 800 kPa) can be used for compressed air supply. Working pressure should not exceed 6 bar (600 kPa).

Ideal control sequence reliability can be achieved by operating the control system at a working pressure of 5 bar (500 kPa) without oil. All the control systems for the 19 exercises are set up using the equipment set for the TP101 basic level. The theoretical fundamentals for understanding this series of exercises are included in the textbook: 

Pneumatics, basic level

Data sheets for the individual components are also available (cylinders, valves, measuring instruments etc.).


VII

Work instructions and safety precautions

General  Trainees should only work with the control systems under the supervision of a trainer.  Observe specifications included in the data sheets for the individual components and in particular all safety instructions! Mechanical  Mount all the components securely onto the profile plate.  Limit switches must not be actuated frontally.  Danger of injury during troubleshooting! Use a tool to actuate the limit switches, for example a screwdriver.  Only reach into the set-up when it’s at a complete standstill. Electrical  Electrical connections must only be established and interrupted in the absence of voltage!  Only use connector cables with safety plugs for electrical connections.  Only use low-voltage (max. 24 V DC). Pneumatics  Do not exceed the maximum permissible pressure of 6 bar (600 kPa).  Do not switch on the compressed air until all of the tubing connections have been completed and secured.  Do not disconnect tubing while under pressure.  Danger of injury when switching compressed air on! Cylinders may advance and retract automatically.  Danger of accident due to tubing slipping off! – Use shortest possible tubing connections. – Wear safety glasses. – In the event that tubing slips off: Switch compressed air supply off immediately.  Pneumatic circuit set-up: Connect the components using plastic tubing with an outside diameter of 4 or 6 mm. Push the tubing into the push-in connector as far as it will go.  Switch compressed air supply off before dismantling the circuit.  Dismantling the pneumatic circuit: Press the blue release ring down, after which the tubing can be pulled out.

VIII


The mounting boards for the components are equipped with mounting variant A, B or C: Variant A, snap-in system Lightweight components that are not load-bearing (e.g. directional control valves). Simply clip the components into the slot on the profile plate. Release the component from the slot by actuating the blue lever. Variant B, bolt-on system Components with medium load capacity (e.g. actuators). These are clamped onto the profile plate using T-head bolts. The blue knurled nut is used for clamping and loosening. Variant C, screw system For components with high load capacity and components that are seldom removed from the profile plate (for example on-off valve with filter regulator). These components are secured with socket head screws and T-head bolts. Observe specifications in the data sheets regarding the individual components.

A stopwatch is required in order to evaluate the control systems once they have been set up. The stopwatch is used to:  Adjust the one-way flow control valves so that the cylinder stroke times comply with the specified values  Adjust time delay valves


IX

Technology module for pneumatics (TP100) The TP100 technology module consists of a multitude of training materials and seminars. The subject matter is focused entirely on pneumatic control systems. Individual components included in the TP100 technology packet can also be included in any of the other modules. Important components of the TP100  Permanent workstation with Festo Didactic profile plate  Compressor (230 V, 0.55 kW, max. 8 bar = 800 kPa)  Equipment sets or individual components (e.g. cylinders, directional control valves, preset counters, stepper modules, logic components, pneumatic proximity switches)  Optional training materials (e.g. optical displays, 5/3-way valve, pulling/pushing load)  Practical training models  Complete laboratory set-ups Training documentation Textbooks

TP101 basic level Fundamentals of pneumatic control technology Maintenance of pneumatic equipment and systems Pneumatics/electropneumatics

Workbooks

Optional teachware

TP101 basic level TP102 advanced level Set of transparencies Magnetic symbols, drawing template FluidSIM® pneumatic simulation software WBT Pneumatics Set of cutaway models with storage case

Seminars P100

Basic pneumatics for machine operators

P111

Fundamentals of pneumatics and electropneumatics

P121

Maintenance and troubleshooting for pneumatic and electropneumatic systems

P-OP

Tracking down wastage – economic use of pneumatics

P-NEU

Pneumatic refresher and update

IW-PEP

Repair and maintenance in the field of control technology – pneumatic and electropneumatic systems

P-AL

Pneumatics for further education

P-AZUBI

Pneumatics and electropneumatics for trainees

Please refer to the current seminar planner for locations, dates and prices. You’ll find further training materials in our catalogue and on the Internet. The training system for automation and technology is continuously updated and expanded. Transparencies, videos, CD ROMs and DVDs, as well as textbooks, are offered in several languages.

X


Learning objectives for the basic level (TP101)                             

Become familiar with the set-up and mode of operation of a single-acting cylinder. Become familiar with the set-up and mode of operation of a 3/2-way valve. Be able to recognise and sketch the various types of actuation for directional control valves. Be able to explain and set up direct actuation. Be able to analyse and evaluate circuits. Become familiar with the set-up and mode of operation of a double-acting cylinder. Become familiar with the set-up and mode of operation of a 5/2-way valve. Be able to explain and set up indirect actuation. Become familiar with the mode of operation of a 5/2-way valve with pneumatic actuation. Become familiar with the difference between a signalling element and a control element. Be able to measure pressure in pneumatic control systems. Be able to differentiate between the various types of flow control and use them in accordance with specifications. Be able to adjust cylinder advancing and retracting speeds. Become familiar with one type of signal storage in pneumatic control systems. Be able to explain and implement AND/OR/NOT logic operations. Be able to explain and set up latching circuits. Become familiar with one option for end-position sensing in cylinders. Be able to combine logic operations. Become familiar with the set-up and mode of operation of a magnetic proximity switch. Be able to differentiate between 5/2-way valves and to select and use them in accordance with specifications. Be able to further develop existing circuits. Become familiar with the set-up and mode of operation of a pressure sequence valve. Be able to set up pressure-dependent control systems. Become familiar with the set-up and mode of operation of a pressure regulator. Be able to analyse existing circuits and optimise them in accordance with specifications. Become familiar with the set-up and mode of operation of a time delay valve. Be able to set up circuits with oscillating motion. Be able to use time delay valves in accordance with specific constraints. Be able to analyse and set up circuits with two cylinders.


XI

Overview of learning objectives per exercise Exercise

1

2

3

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•

•

•

•

•

•

•

•

•

•

•

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Learning Objective Become familiar with the set-up and mode of operation of a single-acting cylinder. Become familiar with the set-up and mode of operation of a 3/2way valve. Be able to recognise and sketch the various types of actuation for directional control valves. Be able to explain and set up direct actuation. Be able to analyse and evaluate circuits.

•

•

•

Become familiar with the set-up and mode of operation of a double-acting cylinder.

•

Become familiar with the set-up and mode of operation of a 5/2-way valve. Be able to explain and set up indirect actuation.

•

•

•

•

Become familiar with the difference between a signalling element and a control element. Be able to measure pressure in pneumatic control systems.

•

•

Be able to differentiate between the various types of flow control and use them in accordance with specifications. Be able to adjust cylinder advancing and retracting speeds.

XII

•

•

•

•


Exercise

1

2

3

4

5

6

7

8

9

10

11

12

13

•

•

•

•

•

•

•

14

15

16

17

•

•

•

18

19

Learning Objective Become familiar with one type of signal storage in pneumatic control systems. Be able to explain and implement AND/OR/NOT logic operations.

•

Be able to explain and set up

•

latching circuits. Become familiar with one option

•

for end-position sensing in cylinders. Be able to combine logic operations. Become familiar with the set-up

•

and mode of operation of a magnetic proximity switch. Be able to differentiate between 5/2-way valves and to select and

•

use them in accordance with specifications. Be able to further develop existing circuits.

•

•

Become familiar with the set-up and mode of operation of a pressure sequence valve. Be able to set up pressuredependent control systems.

•

•

Become familiar with the set-up and mode of operation of a pressure regulator.

•

Become familiar with the set-up and mode of operation of a time delay valve. Be able to set up circuits with oscillating motion.

•

•

Be able to use time delay valves in accordance with specific constraints. Be able to analyse and set up circuits with two cylinders.


•

•

XIII

Equipment set for the basic level (TP101) The equipment set has been put together for basic training in the field of pneumatic control technology. It includes all the components that are necessary for mastering the specific learning objectives and can be supplemented with any other equipment sets. A profile plate and a source of compressed air are also required in order to set up functional control systems. Equipment set for the basic level (TP101)

XIV

Quantity

Designation

Order no.

2

3/2-way roller lever valve, normally closed

152866

1

3/2-way valve with pushbutton, normally open

152861

2

3/2-way valve with pushbutton, normally closed

152860

1

3/2-way valve with selector switch, normally closed

152863

1

3/2-way valve, pneumatically actuated at one end

576302

3

5/2-way double pilot valve, pneumatically actuated at both ends

576303

1

5/2-way valve with selector switch

152862

1


576307

1

Double-acting cylinder

152888

2

One-way flow control valve

193967

2

Pressure gauge

152865

1

Pressure regulator with pressure gauge

539756

1

Pressure sequence valve

152884

1

Single-acting cylinder

152887

1

On-off valve with filter regulator

540691

2

Plastic tubing, 4 x 0.75, silver, 10 m

151496

2

Pneumatic proximity switch with cylinder mounting

539775

1

Pneumatic timer, normally closed

540694

1

Quick exhaust valve

539772

10

Push-in sleeve

153251

10

Push-in T-connector

153128

1

Distributor block

152896

1

Shuttle valve (OR)

539771

2

Dual-pressure valve (AND)

539770


Equipment set symbols Designation

Symbol


2

1

3


4


2

5

3

1


Pressure gauge


2

1 Pneumatic proximity switch

3

2

1

3


2 12


1

3

4

2

14 5

1

3



XV

Designation

Symbol

Shuttle valve 2 1

1

Dual-pressure valve

2 1

1

Pneumatic timer, normally closed

2 t 1

3

Quick exhaust valve

2 1

3


1

2


2

12

1

3



XVI


Designation

Symbol


1 2

3


2

1

3

Distributor block

Connectors


XVII

Allocation of equipment per exercise Exercise

1

2

3

4

1

1

1

1

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Equipment Cylinder, single-acting Cylinder, double-acting

1 1


1

1

1

1

1

1

1

1

1

1

1

1

1

2

2

1

2

2

2

2

2

2

2

1

2

2

1

1

1

1

2

2

1

1

1

1

Quick exhaust valve

1

Pressure gauge 3/2-way valve, pushbutton, normally closed

1

2

2

1

1

3/2-way valve, pushbutton,

1 2 2

2

1

1 1

2

1

2

2

1

1

1

normally open 3/2-way valve, selector switch, normally closed

1

1

2

1


1

Pneumatic proximity switch

2

3/2-way pneumatic valve

2

2

1

1

2

2

1

3/2-way pneumatic double pilot valve 5/2-way valve, selector

1

1

1

switch 5/2-way pneumatic valve

1

1

5/2-way pneumatic double pilot valve

1

1

1

Shuttle valve

1

1

Dual-pressure valve

1 1

1 2

1

1

1

1

1 2

1

1

1

2


1

1

1

Pressure regulator with

1

2

1

1

1

1

pressure gauge Time delay valve, normally closed

1

1

Distributor block

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

On-off valve with filter

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

regulator

XVIII


Practical tools for the trainer Learning objectives The basic learning objectives for the exercises in this module are the systematic sketching of circuit diagrams as well as the practical set-up of a control system on the profile plate. This direct interaction involving both theory and practice ensures faster, long-term learning. Each exercise has its own individual learning objectives; the specific learning objectives are documented in the matrix. Required time The time required for the exercises depends on the learner’s previous knowledge of the subject matter. For training a skilled labourer in metalworking or electrical installation: approx. 2 weeks. For training a technician or engineer: approx. 1 week. Equipment sets The exercises and the equipment sets matched each other. For all 19 exercises you’ll only need the components included in the equipment set for TP101 basic level. Each exercise in the basic level can be set up on a profile plate.

Structure of the exercises All 19 exercises have the same structure and are broken down into:  Title  Learning objectives  Presentation of the problem  Parameters  Project assignment  Layout  Worksheets The solutions for all the 19 exercises are included in the trainer’s manual.


XIX

Designations of the components Pneumatic components are designated in circuit diagrams to DIN ISO 1219 2. All the components included in any given circuit have the same primary identifying number. Letters are assigned depending on each respective type of component. Consecutive numbers are assigned if several components of the same type are included within a single circuit. Pressure lines are designated with a P and are numbered separately. Cylinders: Valves: Sensors: Signal inputs: Accessories:

1A1, 2A1, 2A2 ... 1V1, 1V2, 1V3, 2V1, 2V2, 3V1 ... 1B1, 1B2 ... 1S1, 1S2 ... 0Z1, 0Z2, 1Z1 ...

CD ROM contents The CD ROM provides you with additional media. The worksheets and solutions have been saved as PDF files on the CD ROM that is included with the trainer’s manual. The CD ROM contains the following folders:  Operating instructions  Demo  Festo catalogue  FluidSIM® circuit diagrams  Industrial applications  Presentations  Product information  Videos Operating instructions Operating instructions for the various components included in the technology module are available. These instructions are helpful when using and commissioning the equipment. FluidSIM® demo version A demo version of the FluidSIM® pneumatics software package is included on the CD ROM. Even this demo version is suitable for testing control systems developed by the user.

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Festo catalogue The relevant pages from the Festo catalogue will be provided with selected components. The representations and descriptions of the components are intended to demonstrate how the components are presented in an industrial catalogue. Additional information regarding the components is also included. FluidSIM® circuit diagrams The FluidSIM® circuit diagrams for all 19 exercises included in the technology module are contained in this directory. Industrial applications Photos and graphics representing industrial applications are made available. These can be used to illustrate individual tasks. Project presentations can also be supplemented with these illustrations. Presentations Contains short presentations of the components included in the technology module. These can be used, for example, to create project presentations. Product information This directory contains product information and data sheets from Festo for the components included in the technology module. This is intended to demonstrate which information and data are available for industrial components. Videos Several videos of industrial applications complete the media provided with the technology module. Short clips demonstrate the applications in their actual industrial environments.


XXI

Equipment set for the advanced level (TP102) The equipment set for the advanced level has been put together for further training in the field of pneumatic control technology. The two equipment sets (TP101 and TP102) include components that are necessary for mastering the predefined learning objectives and can be supplemented as required with other equipment sets from the training system for automation and technology. Equipment set for the advanced level (TP102)

XXII

Quantity

Designation

Order no.

1

3/2-way roller lever valve with idle return, normally closed

152867

2


152860

1

3/2-way valve with mushroom actuator (red), normally open

152864

4


576302

2


576303

2


152888

2


193967

2

Plastic tubing, 4 x 0.75, silver, 10 m

151496

1

Pneumatic timer, normally open

539759

2

Non-return valve, piloted non-return function

540715

1

Back pressure limit valve

152868

10

Push-in sleeve

153251

1

Stepper module

152886

20

Push-in T-connector

153128

1

Pneumatic preset counter

152877

1

Shuttle valve (OR)

539771

1

Shuttle valve, 3-way (OR)

152882

1

Dual-pressure valve, 3-way (AND)

152883


Learning objectives for the advanced level (TP102)                       

Detect end-positions without limit switches Understand and set up flip-flop circuits (flip-flop, double pilot valve) Convert a 3/2 and/or a 5/2-way valve Evaluate, use and adjust various sensors Explain the function of a back pressure end stop Explain the function of stepper modules Develop basic sequence control systems (continuous cycle) Implement a sequence control system with the following operating modes: automatic/manual, start and reset Implement an OR operation for feedback signals Set and coordinate delays Be able to abort delay times with an OR operation Implement a sequence control system with idle step (3 steps) Describe and set up variable step repetition within a motion sequence using a preset counter Develop an input circuit with self-latching loop including the following functions: automatic/manual, start, stop (at end of cycle) and reset Evaluate and use sensors for material sensing Actuate the final control element with two steps via a shuttle valve (double cylinder stroke) Use a proximity switch within the stroke sub-range in order to reverse cylinder motion Development of an input circuit for a sequence control system with secure pilot air, as well as start, emergency stop and reset functions Stop the cylinder within the sub-stroke range (positioning) by pressurising at both ends (preloading) Adjust proximity switches in the end positions and within the sub-stroke range Combined use of quick exhaust valve and pressure regulator with pressure gauge Set up an inverted timer signal Implement a control system with guide features in combination with sequence control


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XXIV


Exercise 1: Pressing cheeses Learning objectives After completing this exercise you’ll:  Be familiar with the set-up and mode of operation of a single-acting cylinder.  You’ll be able to calculate the piston force of a single-acting cylinder.  Be familiar with the set-up and mode of operation of a normally closed 3/2-way valve.  Be able to recognise and sketch the various types of actuation for directional control valves.  Be able to explain and set up direct actuation.

Presentation of the problem Presses are used to press cheeses into moulds during the production process. Develop a control system with which this process can be executed

Layout

Cheese production


1

Exercise 1: Pressing cheeses

 

Parameters Use a double-acting cylinder. Pneumatically control the cylinder using a manually actuated valve.

1. 2. 3. 4. 5. 6. 7.

Project assignment Describe the mode of operation of a single-acting cylinder. Describe the mode of operation of a normally closed 3/2-way valve. Complete the pneumatic circuit diagram for the pressing tool. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

1. 2. 3. 4. 5.

Procedure The cheeses are placed into the tool manually. When the pushbutton is activated, the cylinder advances and presses the cover onto the tool. The pushbutton is pressed and held until the pressing operation has been completed. When the pushbutton is released, the cylinder is retracted and the tool can be accessed. The cheese can be removed.

Safety note Limit pressure at the service unit for this exercise to a maximum of3.5 bar (350 kPa). Immediately deactivate compressed air supply if the tubing slips off.

2



Set-up and mode of operation of a single-acting cylinder 1

2

3

8

7

4

5

6

Circuit symbol and schematic diagram of a single-acting cylinder

–

Compare the circuit symbol shown above with the schematic diagram of the single-acting cylinder. Determine whether or not the two representations coincide with each other. The two representations coincide with each other.

–

Describe the set-up and mode of operation of a single-acting cylinder. The compressed air flows into the cylinder’s piston chamber. Pressure is built up in the chamber and force is applied to the surface of the piston as a result. If this force exceeds static friction, the piston is advanced. Pressure is not built up to full operating pressure until the piston is fully advanced. When this pressure drops, the integrated return spring forces the piston back into its initial position. Spring force is not great enough to move heavy loads attached to the piston rod. Hence single-acting cylinders only perform work in a single direction.

–

Match up each component with the corresponding number from the above drawing.

Component

Designation

3

Cylinder barrel

1

End cap

6

Bearing cap

5

Piston rod

8

Piston

7

Spring return

2

Supply port

4

Exhaust port

Table of component designations


3


Calculate the piston force of a single-acting cylinder Theoretical piston force is calculated using the following formula: Fth Fth A

= = = =

p D

= =

Ap theoretical piston force (N) effective piston surface (sq. metres) D2   ) 4 working pressure (Pa) (

cylinder diameter (m)

Piston force Feff is important in actual practice. Frictional resistance has to be taken into consideration when calculating piston force. Under normal operating conditions (pressure range of 4 to 8 bar or 400 to 800 kPa), it is assumed that friction forces (FR) amount to roughly 10% of the theoretical piston force. The following applies to the effective piston force of single-acting cylinders: Feff Feff FR FF –

= = = =

A  p – (FR + FF) effective piston force (N) friction force (approx. 10% of Fth ) (N) return spring force (N)

Calculate the effective piston force for the advance stroke of the used cylinder with a working pressure of 6 bar (600 kPa).

A= (

0.022  3.14 ) = 0.000314 4

Feff = 0.9  A  p – FF Feff = 0.9  (0.000314)  600,000 – 13.6 Feff = 169.56 – 13.6 = 155.96 N

Note TThe piston diameter of the used cylinder is 20 mm and spring return force is 13.6 N.

4



Mode of operation of a normally closed 3/2-way valve –

Complete the circuit symbol of a manually actuated, normally closed 3/2-way valve with spring return.

2

3 2

1

1

3

Circuit symbol and schematic representation of a normally closed 3/2-way valve

–

Describe the mode of operation of the 3/2-way valve. A 3/2-way valve has 3 ports and 2 switching positions. It’s represented in the normal position. Normally closed means that compressed air cannot flow through the valve. When the pushbutton is actuated the valve is opened, thus allowing air to flow and the piston of a connected cylinder is advanced.


5


Complete the pneumatic circuit diagram –

Complete the pneumatic circuit diagram for the control system and enter the port designations. 1A1

1S1

2

1

3 0Z2

0Z1

1 2

3

Pneumatic circuit diagram

6



Sequence description –

Set up the control system and describe its working sequence. Initial position Valve 1S1 is closed in its initial position. The piston rod of cylinder 1A1 is retracted.

Step 1-2 When the pushbutton on 3/2-way valve 1S1 is pressed, compressed air flows into the piston chamber of cylinder 1A1 and the piston rod is advanced.

Step 2-3 When the pushbutton is released, valve 1S1 is exhausted and cylinder 1A1 returns to its initial position due to force applied by the return spring.


7


Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –

Create an equipment list by entering the required components and their quantities in the table below.

Quantity

Designation

1

Cylinder, single-acting

1


1

Distributor block

1


1

Compressed air source

Equipment list

8


Exercise 2: Opening a fodder silo Learning objectives After completing this exercise you’ll:  Be familiar with the set-up and mode of operation of a normally open 3/2-way valve.  Be able to recognise and sketch the various types of actuation for directional control valves.  Be able to explain and set up direct actuation.

Presentation of the problem The slide of a fodder silo is to be opened by pressing a pushbutton. When the pushbutton is released, the slide is once again closed.

Layout

Fodder silo


9

Exercise 2: Opening a fodder silo

 

Parameters A single-acting cylinder is to be used. The cylinder will be pneumatically controlled using a pushbutton.

1. 2. 3. 4. 5. 6.

Project assignment Answer the questions on the normally open 3/2-way valve. Create the pneumatic circuit diagram for controlling the slide. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create the equipment list.

Procedure 1. When the pushbutton is activated, the cylinder is retracted to the retracted end position. 2. The pushbutton is pressed and held for as long as the slide is to remain open. 3. When the pushbutton is released, the cylinder is advanced and the slide closes the opening in the silo.

Safety note Limit pressure at the service unit to a maximum of 3.5 bar (350 kPa) for this exercise.

10



Mode of operation of a 3/2 way valve –

Complete the circuit symbol of the 3/2-way valve. It needs to include the following functions: manual actuation, spring return, normally open. 2

1

3

Circuit symbol, 3/2-way valve, normally open

2

1 3

Schematic representation of a 3/2-way valve, normally open

–

Explain the mode of operation of a 3/2-way valve, normally open. A normally open 3/2-way valve has 3 controlled ports and 2 switching positions. It’s represented in the normal position. This is a normally open variant of the valve. This means that compressed air flows through the valve to the cylinder and holds the cylinder’s piston in the advanced end position. When the pushbutton is activated, the valve stops the flow of compressed air, the cylinder is exhausted via the valve and the piston is retracted.


11


Change the pneumatic circuit diagram –

Change the pneumatic circuit diagram for the control system and enter the port designations. 1A1

1S1

2

1

3 0Z2

0Z1

1 2

3

Circuit diagram

Note Please note that control systems must be represented in their initial positions.

12




Set up the control system and describe its working sequence. Initial position The 3/2-way valve is open in the free-flow direction and the piston chamber is pressurised. The piston at cylinder 1A1 is advanced.

Step 1-2 If pushbutton 1S1 is activated, the piston is exhausted via the 3/2-way valve and cylinder 1A1 is retracted.

Step 2-3 When the pushbutton is released, the spring forces the 3/2-way valve into its initial position, the piston chamber is once again pressurised and cylinder 1A1 advances again.

Safety note Limit pressure at the service unit for this control system to a maximum of 3.5 bar (350 kPa).


13


Change the equipment list –

Change the equipment list shown below such that it corresponds with the requirements for this control system.

Quantity

Designation

1


1

Distributor block Tubing material

1


1

3/2-way valve, manually actuated, normally closed

Equipment list

Quantity

Designation

1


1

Distributor block Tubing material

1


1

3/2-way valve, manually actuated, normally open

Equipment list

14


Exercise 3: Clamping boards to a saw bench Learning objectives After completing this exercise you’ll:  Be able to recognise and sketch the various types of actuation for directional control valves.  Be able to explain and set up direct actuation.  Be able to analyse and optimise control systems.

Presentation of the problem Boards are manually laid on the saw bench where they are cut to length with a circular saw. The sawing operation is controlled from a separate control panel and thus the boards are pneumatically clamped to the saw bench. The control system is implemented with only one cylinder for the test set-up.

Layout

Sawing fixture


15

Exercise 3: Clamping boards to a saw bench

 

Parameters Use one of the control systems from the previous exercises and modify it for this task. Use, by way of example, only one single-acting cylinder to design the control system.

1. 2. 3. 4. 5.

Project assignment Complete the pneumatic circuit diagram for the clamping tool. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Change the equipment list.

1. 2. 3. 4.

Procedure A board is manually laid on the saw bench. After activating a switch, the cylinder advances and clamps the board. The cylinder remains in the advanced position, even when the switch has been released. After turning the switch back to its initial position, the cylinder is retracted to the retracted end position, where it remains until the switch is activated again.


16




Complete the circuit diagrams shown below by entering the required type of actuation. a)

b)

Circuit diagram

–

Select the best control system and justify your answer. The correct solution is a). Reason: The cylinder has to be in its retracted end position when the switch is deactivated.


17



Set up the control system and describe its working sequence. Initial position The valve’s free-flow direction is closed. The cylinder’s piston rod is retracted.

Step 1-2 When selector switch 1S1 is activated, compressed air flows into the piston chamber and the cylinder is advanced.

Step 2-3 When the selector switch is reset, the valve is exhausted and the cylinder returns to its initial position due to force applied by the return spring.

Safety note Limit pressure at the service unit for this control system to a maximum of 3.5 bar (350 kPa).

18



Change the equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –

Change the equipment list by entering the required components in the table below.

Quantity

Designation

1


1

3/2-way valve with switch, normally closed

1

Distributor block

1


1


Changed equipment list


19


20


Exercise 4: Sorting packages Learning objectives After completing this exercise you’ll:  Be familiar with the set-up and mode of operation of a double-acting cylinder.  Be able to calculate the piston force of a double-acting cylinder for both the advance and the return strokes.  Be familiar with the set-up and mode of operation of a 5/2-way valve.

Presentation of the problem Packages are sorted manually from a roller conveyor into large containers at a sorting station. When the containers are full, they’re removed and new containers are provided. At this point the material flow should be interrupted, but the roller conveyor continues to run. The material flow is interrupted by mechanical blocking (slide). The slide has to be operated at the sorting station.

Layout

Sorting station


21

Exercise 4: Sorting packages

Parameters A double-acting cylinder will be used, because work is carried out during both the advance and the return strokes.



1. 2. 3. 4. 5. 6. 7.

Project assignment Describe the set-up of a double-acting cylinder. Describe the mode of operation of a 5/2-way valve. Create a pneumatic circuit diagram for the package blocking slide. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. When the selector switch is activated, the cylinder advances and pushes the slide into the flow of material. 2. The cylinder remains in this position after releasing the selector switch and the material flow remains interrupted. 3. After turning the selector switch to its initial position, the cylinder moves to its retracted end position and the material flow is resumed. The cylinder remains in this position until the selector switch is activated again.


22



Set-up of a double-acting cylinder 1

2

3

7

5

4

6

Circuit symbol and schematic diagram of a double-acting cylinder

–

Compare the circuit symbol shown above with the schematic diagram of the double-acting cylinder. Determine whether or not the two illustrations are the same. The two illustrations are the same.

–

Make a note of the characteristics of a single-acting and a double-acting cylinder designs that are the same as well as those that are different. Both cylinder designs include cylinder barrel, piston and piston rod. The double-acting cylinder doesn’t have a return spring. The double-acting cylinder has 2 supply ports.

–

Match the numbers from the schematic drawing with the individual components of the double-acting cylinder.

Component

Designation

1

Supply port, piston chamber

2

Piston

3

Cylinder barrel

4

Supply port, piston rod chamber

5

Piston rod

6

Bearing cap

7

End cap


23


Mode of operation of a double-acting cylinder –

Describe the mode of operation of a double-acting cylinder. As opposed to a single-acting cylinder, more air is consumed. As the piston surfaces differ in size, the forces vary with identical pressure.

Forward stroke Compressed air flows into the cylinder through the piston chamber supply port. Pressure is built up in the chamber and force is applied to the surface of the piston as a result. If this force exceeds static friction, the piston is advanced. Air in the piston rod chamber escapes through the port at the piston rod end. Pressure is not built up to full force until the piston is fully advanced.

Return stroke After reversing, air flows through the supply port at the piston rod chamber where it builds up pressure until the piston rod is retracted. Air escapes from the piston chamber through the piston chamber port.

24



Calculate the piston force for the advance and return strokes Theoretical piston force is calculated using the following formula: Fth

=

Ap

The following applies to double-acting cylinders: Advance stroke Feff = (A  p) – FR Return stroke Feff = (A'  p) – FR Feff A

A'

= =

effective piston force (N) effective piston surface (m2)

=

(

=

effective piston ring surface (m2)

= p FR D d –

= = = =

D2   ) 4

(D 2  d 2 )

 4

working pressure (Pa) friction force (approx. 10% of Fth ) (N) cylinder diameter (m) piston rod diameter (m)

Calculate the effective piston force for the advance and return strokes of the cylinder with a working pressure of 6 bar (600 kPa). Forward stroke Feff Feff Feff

= = =

(A  p) – FR 0.9  A  p 0.9  0.000314  600,000

Feff

=

169.66 N

Return stroke Feff Feff Feff

= = =

(A'  p) – FR 0.9  (0.000314 – 0.00005024)  600,000 0.9  0.00026376  600,000

Feff

=

142.4 N

Note The piston diameter of the cylinder is 20 mm and the piston rod diameter is 8 mm.


25


Determine the requirements for the directional control valve –

Write down the requirements for the directional control valve. Compressed air must be available in both switching positions, because the double-acting cylinder cannot be retracted without compressed air. Venting of the other cylinder chamber must be ensured in each case.

–

Indicate why the directional control valve has to be actuated with a switch. A switch has to be used because a pushbutton cannot be held in the activated position for as long as it takes to replace the containers.

26



Mode of operation of a 5/2 way valve –

Complete the circuit symbol of a manually actuated, 5/2-way valve with spring return and locking function, and enter the port designations.

4

5

2

1

3 5

4

1

2

3

Circuit symbol and schematic representation of a 5/2-way valve

–

Describe the mode of operation of a 5/2-way valve when valve port 2 is connected to the piston rod end of a double-acting cylinder. Mode of operation of a 5/2 way valve, unactuated When the 5/2-way valve is not actuated, the return spring holds the valve in its initial position. The piston rod end of the cylinder is pressurised and the piston rod is retracted.

Mode of operation of a 5/2 way valve, actuated When the 5/2-way valve is actuated, the force of the valve return spring is overcome and the valve is reversed. In this state, the supply port is connected to the piston end of the cylinder via the valve while the piston rod end is exhausted via the valve. Pressure which is built up at the piston end causes the piston rod to advance. As soon as the piston rod has reached its advanced end position, maximum operating pressure is built up at the piston end of the cylinder.

Actuation with a switch If the valve is actuated with a switch, the valve remains in either of its positions until the switch is reversed again.


27


Complete the circuit diagram –

Complete the circuit diagram shown below. 1A1

1S1

4

2

5

1

3 0Z2

0Z1

1 2

3


28




Create an equipment list by entering the required components in the table below.

Quantity

Designation

1

Cylinder, double-acting

1


1

Distributor block

1


1



29


30


Exercise 5: Stopping milk bottles Learning objectives After completing this exercise you’ll:  Be able to explain and set up indirect actuation.  Be familiar with the mode of operation of a 5/2-way valve with pneumatic actuation.  Be familiar with the difference between a signalling element and a control element.

Presentation of the problem A filling system fills bottles with milk. The bottles are fed to the system on a conveyor belt and are stopped underneath the filler using a pneumatic cylinder. The positioning accuracy of the stopping operation will be checked during a test set-up. The stopping operation will be activated at the system’s control panel.

Layout

Milk bottle filling system


31

Exercise 5: Stopping milk bottles

  

Parameters Stopping of the material flow will be carried out at a central control panel. As compressed air is available at the control panel, a pneumatic solution will be used. The control valve for the cylinder will be pneumatically actuated.

Project assignment 1. Determine the requirements for the control system with regard to actuating components and the control element. 2. Complete the pneumatic circuit diagram for stopping the material flow. 3. Set up the control system. 4. Double-check the control system configuration. 5. Describe the mode of operation of the control system. 6. Create an equipment list.

Procedure 1. When the selector switch is activated, the cylinder advances and pushes the slide into the flow of material, thus stopping the bottles. 2. After setting the selector switch back to its initial position, the cylinder is in its retracted end position and once again enables material flow. 3. The cylinder remains in this position until the selector switch is activated again.

Additional task Explain the term “indirect control”.

32




Complete the circuit diagram shown below and enter the missing connection and component designations. 1A1

1V1

2

4

14 5 1S1

1

2

1

3 0Z2

3

0Z1

1 2

3


Note The on-off valve with filter regulator and the distributor block are not shown. These components are required in order to set up the control system.


33



Explain the mode of operation of the control system by describing its operating sequence. Initial position The signalling element and the control element are in the position generated by the return spring.

Step 1-2 When the selector switch at the 3/2-way valve 1S1 is actuated, pneumatic control port 14 at 5/2-way valve 1V1 is pressurised with compressed air. The 5/2-way valve is reversed as a result. The left-hand port (piston end) of the double-acting cylinder is pressurised with compressed air, and the right-hand port (piston rod end) is exhausted. The cylinder advances.

Step 2-3 When the selector switch is returned to its initial position, the compressed air supply to the 3/2-way valve is blocked, the 5/2-way valve looses pressure at control port 14 and the valve piston is returned to its initial position by the return spring. The piston end of the cylinder is thus exhausted and the piston rod end is pressurised with compressed air. The cylinder travels to its retracted end position.

34





Quantity

Designation

1


1

Pneumatic 5/2-way valve with spring return

1

Normally closed 3/2-way valve with selector switch

1

Distributor block

1


1



35


Additional task –

Explain the term “indirect control”. Indirect control Cylinders with large piston diameters have high air consumption rates. Control elements with high nominal flow rates must be used to actuate them. If the force is too great for manual actuation of the valve, indirect actuation must be set up. In doing so, a signal is generated by a second, smaller valve, which then provides the force required in order to switch the control element.

36


Exercise 6: Opening and closing a pipeline Learning objectives After completing this exercise you’ll:  Be able to measure pressure in pneumatic control systems.  Be able to differentiate between the various types of flow control and use them in accordance with specifications.

Presentation of the problem The gate in a pipeline needs to be opened and closed. Actuation is via a valve with selector switch. A double-acting cylinder will be used as an actuator.

Layout

Wastewater treatment


37

Exercise 6: Opening and closing a pipeline



Parameters The gate must be opened and closed slowly because the pipeline would otherwise be overloaded (the forming of waves should be avoided). The speed of the opening and closing strokes should be steady.

1. 2. 3. 4. 5. 6.

Project assignment Create a pneumatic circuit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list. Observe pressure conditions upstream and downstream of the flow control and document them.



Procedure 1. When the selector switch is activated, the cylinder is advanced and opens the gate. 2. When the selector switch is returned to its initial position, the cylinder is retracted to its initial position and the gate is closed.

 

Additional tasks At which pressure level do you observe jerking motion? Explain how jerking motion occurs.


38



Mode of operation of a one-way flow control valve

1

1

2

2 Circuit symbol and schematic diagram of a one-way flow control valve

–

Describe the mode of operation of a one-way flow control valve. Air is restricted in one direction only with a one-way flow control valve. The non-return valve inhibits the flow of air in one direction and air can only flow through the selected cross-section. Air flows freely in the other direction through the open non-return valve. These valves are used primarily for controlling the speed of the pneumatic cylinders. The speed of the piston rod can be controlled with one-way flow control valves by adjusting the volumetric flow rate.

–

Describe two types of flow control used with double-acting cylinders. Supply air flow control In the case of supply air flow control, the one-way flow control valves are installed such that air being fed to the cylinder is restricted. Exhaust air can escape freely on the downstream side via the non-return valve. Feed speed irregularities occur as the result of even the smallest load fluctuations at the piston rod, for example in the case of limit switch overtravel. A load in the direction of cylinder motion accelerates the cylinder beyond the selected value.

Exhaust air flow control In the case of exhaust air flow control, supply air flows freely to the cylinder and the flow control in the exhaust line resists the escaping air. The piston is held between two air cushions, which are generated as a result of supply air pressure and resistance caused by the flow control. This one-way flow control valve arrangement contributes significantly to improved feed characteristics. Exhaust air flow control should be used with double-acting cylinders.

–

Explain how a one-way flow control valve is tested for correct functioning. A one-way flow control valve is tested for correct functioning by means of two pressure gauges. The pressure gauges are connected directly upstream and downstream from the valve under test.


39


Create the pneumatic circuit diagram –

Complete the circuit diagram shown below. Complete the symbols for the one-way flow control valves.. Observe the specified basic conditions when doing so. 1A1

1Z2

1V1

1Z1

1S1

1

1

2

2

4

5

1V2

2

1

3


40





Quantity

Designation

1


2


2

Pressure gauge

1


1

Distributor block

1


1



41



Set up the control system and describe its operating sequence. Initial position In the initial position, the piston is in the retracted end position. The piston chamber is exhausted via 5/2-way valve 1S1.

Step 1-2 When the 5/2-way valve is reversed, the piston chamber in the cylinder is pressurised via the one-way flow control valve. The cylinder travels to its advanced end position.

Step 2-3 After resetting the switch, the cylinder’s piston rod chamber is pressurised via the one-way flow control valve and the 5/2-way valve. The cylinder travels to its retracted end position. The required retraction time is adjusted with the one-way flow control valve. Use a stopwatch to this end.

42



Additional tasks –

At which pressure level do you observe jerking motion? Jerking motion occurs in the case of very low operating pressure or excessive restriction.

–

Explain how jerking motion occurs. It’s caused by pressure building up and working against static friction and sliding friction. Pressure builds up at the stationary piston and works against static friction. If force due to pressure exceeds the friction coefficient, the piston is advanced and minimal sliding friction comes into play. But then the air increases again and pressure drops, because it can’t be built back up quickly enough; the piston stops. This sequence is repeated. The piston “stammers”.


43


44


Exercise 7: Shutting off a pipeline Learning objectives After completing this exercise you’ll:  Be able to adjust cylinder advancing and retracting speeds.  Be able to differentiate between the various types of flow control and use them appropriately.

Presentation of the problem A filling system fills bottles with milk. The pipes through which the milk flows are opened and closed using a gate. The gate should be opened slowly in order to prevent any spillage at the beginning of the filling process. Closing, on the other hand, should take place as quickly as possible.

Layout

Milk bottle filling


45

Exercise 7: Shutting off a pipeline



Basic condition Speed control should enable a smooth opening process.

1. 2. 3. 4. 5. 6.

Project assignment Select the appropriate type of flow control. Create a pneumatic circuit diagram for the shut-off mechanism. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. A gate valve is opened slowly after activating a selector switch. 2. The gate valve is closed quickly when the selector switch is returned to its initial position.


46



Select the type of flow control Determine whether supply air or exhaust air flow control is required for the application. –

Justify your selection and write your reasons down. Exhaust air flow control is the right selection for the application. Load-independent, uniform feed speed is ensured by means of exhaust air flow control.


47


Create the pneumatic circuit diagram –

Complete the circuit diagram shown below. Observe the specific constraints when doing so. 1A1

1

1V1

2

1S1

4

5

2

1

3


48



Create an equipment list –


Quantity

Designation

1


1


1


1

Distributor block

1


1



49



Set up the control system and describe its operating sequence. Initial position The piston’s initial position is the retracted rear end position. The piston chamber is exhausted via 5/2way valve 1S1.

Step 1-2 When the 5/2-way valve is reversed, the piston chamber in the cylinder is pressurised with compressed air. The piston rod chamber is exhausted via 5/2-way valve 1S1. The cylinder travels slowly to its advanced end position. The required advancing time is adjusted with the one-way flow control valve.

Step 2-3 After resetting the switch, the cylinder’s piston rod chamber is pressurised via the one-way flow control valve and the 5/2-way valve is pressurised without flow control. The piston chamber is exhausted via 5/2-way valve 1S1. The cylinder travels to its retracted end position.

Note This control system works with exhaust air flow control. Use a stopwatch in order to set the required time value. The setting can be secured with a lock nut.

50


Exercise 8: Actuating a shut-off device Learning objectives After completing this exercise:  You’ll be familiar with one type of signal storage in pneumatic control systems.  You’ll be able to adjust cylinder advancing and retracting speeds.

Presentation of the problem The gate in a filling system for plastic pellets needs to be closed quickly. However, it should be opened slowly.

Layout

Plastic pellet filling system


51

Exercise 8: Actuating a shut-off device

 

Parameters A double-acting cylinder will be used. The closing operation should be executed by the cylinder’s forward stroke.

1. 2. 3. 4. 5. 6. 7.

Project assignment Describe the mode of operation of a quick exhaust valve. Describe the mode of operation of a 5/2-way double pilot valve. Draw a pneumatic circuit diagram for the shut-off mechanism. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. A shut-off mechanism (ball valve) is opened slowly after activating a pushbutton. 2. The shut-off mechanism is closed quickly after activating a second pushbutton.


52



Mode of operation of a quick exhaust valve 3

2

2 1

3

1

Circuit symbol and schematic diagram of a quick exhaust valve

–

Describe the mode of operation of a quick exhaust valve. Increased piston speeds during the return stroke can be achieved with single and double-acting cylinders using quick exhaust valves, because flow resistance is thus reduced for the exhaust air. Compressed air flows from the pilot valve to the cylinder via the quick exhaust valve. Exhaust port 3 is closed at this time. When pressure at port 1 drops, exhaust flow occurs from 2 to 3. In order to implement optimised quick exhaust, the valve must be connected directly to the cylinder’s supply port.


53


Mode of operation of a 5/2-way double pilot valve

14

5

4

1

2

3

12

Schematic diagram of a 5/2-way double pilot valve

–

Explain the mode of operation of the 5/2-way double pilot valve. A 5/2-way double pilot valve has 5 working ports and 2 switching positions. The valve is equipped with a latching function; a short signal (pulse) suffices for reversal. The valve piston is moved to the opposite switching position by means of a compressed air pulse at one of the two pilot ports (12/14). The valve piston is held in this position by the compressed air at the working port until a compressed air pulse at the other side of the valve reverses the valve back to its previous position. If signals are present at both pilot ports, the first signal to arrive is dominant. A pneumatic signal at pilot port 12 causes flow from port 1 to port 2. A pneumatic signal at pilot port 14 causes flow from port 1 to port 4.

–

Describe the performance of the valve depicted above when port 14 is briefly pressurised with compressed air. When port 14 is pressurised, the valve piston is moved to the right and directs compressed air from port 1 to port 4. Port 2 is exhausted via port 3. When port 14 is once again unpressurised, the valve position remains in this position by compressed air from port 1.

54





1Z1 1V3 1V2

1

1

2

1V1

4

2 12

5

1

3

1S2

2

1

3

2

14

1S1

2

3

2

1

3



55



Set up the control system and describe its working sequence. Initial position The piston’s initial position should be the retracted end position. The piston chamber is exhausted via 5/2-way double pilot valve 1V1 and the piston rod chamber is pressurised. If the piston is in the advanced end position, it has to be moved to the retracted end position by actuating 1S2.

Step 1-2 After actuating 3/2-way valve 1S1, the 5/2-way double pilot valve is reversed and the cylinder’s piston chamber is pressurised via the one-way flow control valve. The double-acting cylinder travels to its advanced end position. The piston rod chamber is vented via the quick exhaust valve. The piston remains in this end position, even when 1S1 is released again.

Step 2-3 The 5/2-way double pilot valve is reversed by actuating 3/2-way valve 1S2. The cylinder’s piston rod chamber is pressurised via the quick exhaust valve. The cylinder’s piston chamber is exhausted via the one-way flow control valve and the 5/2-way double pilot valve. The cylinder travels to its retracted end position.

Retracting time The required retraction time is adjusted using the one-way flow control valve. Use a stopwatch to this end. This setting can be secured with the lock nut.

56




Create an equipment list by entering the required components to the table below.

Quantity

Designation

1


1


1

Quick exhaust valve

1

Pressure gauge

1

5/2-way double pilot valve

2


1

Distributor block

1


1



57


58


Exercise 9: Expanding the control system for pressing cheeses Learning objectives After completing this exercise you’ll:  Be able to expand existing control systems.  Be able to analyse a proposed solution.  Be able to implement an OR operation.

Presentation of the problem Presses are used to press cheeses into moulds during a cheese production process. The cheese presses are operated by using one of two pushbuttons, so that pressing can be done at the loading or unloading end. There is a possible solution which, however, does not achieve the piston force required to press a cheese.

Layout

Cheese production


59

Exercise 9: Expanding the control system for pressing cheeses

 

Parameters Design pneumatic control of the cylinder using an additional manually actuated valve. Operation should be possible using either of the valves.

1. 2. 3. 4.

Project assignment Analyse the proposed solution. Complete the pneumatic circuit diagram for the pressing device. Set up the control system. Update the equipment list.

1. 2. 3. 4. 5.

Procedure The cheeses are placed into the press manually. After actuating a pushbutton at the loading or unloading end of the system, the cylinder advances and presses the lid onto the press. The pushbutton is pressed and held until the pressing operation has been completed. When the pushbutton is released, the cylinder is retracted and the press can be accessed. The cheese can be removed.

Safety note Limit pressure at the service unit for this exercise to a maximum of 3.5 bar (350 kPa).

60



Analyse the pneumatic circuit diagram The required functional expansion has been achieved with the help of the control system shown below. However, it has been noticed that the piston force required to press the cheese is not reached. Piston force is only adequate when both pushbuttons are activated simultaneously. 1A1

2

1

2

3

1

3

Circuit diagram for proposed solution

–

Analyse the control system depicted above and explain why the required piston force is not achieved. The required piston force is not reached because part of the operating pressure escapes via the exhaust port of the unactuated valve.


61


Mode of operation of a shuttle valve 2

2 1

1

1

1

Circuit symbol and schematic diagram of a shuttle valve

–

Describe the mode of operation of the required components. The shuttle valve is used for the OR operation. Pneumatic signals at one or both of the inputs 1 cause a signal at the signal output 2. If there’s no input signal, there’s no output signal. If a signal is present at both inputs, the earlier signal arrives at the output.

62




Complete the circuit diagram below. 1A1

1V1 1

1S1

1

1S2

2

1

2

3

2

1

3



63


Update the equipment list The equipment list for the original control system must be changed in order to document the current control system. Quantity

Designation

1


1


1

Distributor block

1


1


Existing equipment list

–

Fill in the table below.

Quantity

Designation

1


1

Shuttle valve

2


1

Distributor block

1


1


Updated equipment list

64


Exercise 10: Clamping a workpiece Learning objectives After completing this exercise you’ll:  Be able to implement an AND operation.  Be familiar with one option for end-position sensing in cylinders.

Presentation of the problem A rotary indexing machine is used for feeding workpieces in production process. The workpieces have to be clamped in the individual workpiece holders for machining. A clamping tool is to be developed and tested by means of a test set-up.

Layout

Rotary indexing machine


65

Exercise 10: Clamping a workpiece

Parameters The clamping process can only be started when the cylinder is in the retracted end position. After activating a second pushbutton, the cylinder returns to the retracted end position and releases the workpiece. Pressure gauges will be installed between the one-way flow control valve and each of the cylinder’s two working ports in order to indicate pressure.

  

1. 2. 3. 4. 5. 6. 7.

Project assignment Describe the mode of operation of a dual-pressure valve. Describe the mode of operation of a 3/2-way roller lever valve. Complete the pneumatic circuit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. A double-acting cylinder can only be advanced when a pushbutton is activated and the cylinder is in the retracted end position; otherwise it’s not possible to insert a workpiece for machining. 2. The clamping cylinder should be held in the advanced end position until the workpiece has been machined. Machining time may vary. 3. The workpiece is released by pressing a second pushbutton.


Additional task What happens if the 3/2-way roller lever valve is readjusted?

66



Mode of operation of a dual-pressure valve 2

2 1

1 1

1

Circuit symbol and schematic diagram of a dual-pressure valve

–

Describe the mode of operation of a dual-pressure valve. The dual-pressure valve is used for the AND operation. Pneumatic signals at both inputs 1 cause a signal at output 2. If there’s only one input signal or none at all, there’s no output signal. If the input signals are generated at different times, the later signal arrives at the output. If the input signals have different pressure values, the signal with the lower pressure value arrives at the output.


67


Mode of operation of a 3/2-way roller lever valve 2

1

3

Circuit symbol for a 3/2-way roller lever valve

–

Describe the mode of operation of a 3/2-way roller lever valve. A 3/2-way roller lever valve has 3 working ports and 2 switching positions. The roller lever is actuated by, for example, a trip cam on a cylinder. Reduced actuation force is achieved by means of pilot control.

–

Explain how the roller lever valve has to be mounted in order to ensure correct functioning of the control system. The roller lever valve must be mounted so that it’s actuated when the cylinder piston is in the retracted end position. If the valve is mounted in front of or underneath the cylinder cam, the roller lever is not actuated and the AND operation cannot be fulfilled. The control system is not started.

68





1B1

1Z1

1Z2

1V3

1V2

1

1

2

2

4

2

14 1V1 1

1S1

1

12 5

2

1

3

1

1B1

2

1V4

3

1

1S2

2

3

2

1

3



69



Set up the control system and describe its working sequence. Initial position Pressure is present. The piston chamber of the double-acting cylinder is exhausted and the piston rod chamber is pressurised. 3/2-way roller lever valve 1B1 is actuated. The cylinder is in its retracted end position.

Step 1-2 When 3/2-way valve 1S1 is actuated, compressed air is applied to both inputs at dual-pressure valve 1V1. Compressed air is now also present at the output of the dual-pressure valve. 5/2-way double pilot valve 1V2 is reversed by the signal at pilot port 14. The cylinder is thus also reversed and the piston advances. 3/2-way roller lever valve 1B1 is switched to its normal position and the output signal at the dual-pressure valve is deactivated. The cylinder is held in the advanced end position by the self-locking loop.

Step 2-3 After activating the pushbutton at 3/2-way valve 1S2, 5/2-way double pilot valve 1V3 is reversed again (signal at pilot port 12). The cylinder’s piston rod chamber is pressurised. The cylinder travels to its retracted end position. 3/2-way roller lever valve 1B1 is actuated again.

70





Quantity

Designation

1


2


2

Pressure gauge

1

5/2-way valve, double piloted

1


1


2


1

Distributor block

1


1



71


72


Exercise 11: Loading wire baskets Learning objectives After completing this exercise you’ll:  Be able to implement a latching circuit with OR operation.

Presentation of the problem Wire baskets are loaded with packages at a loading station. They are positioned at two supply points along the conveyor belt so that the continuous flow of packages doesn’t have to be interrupted. When one wire basket is full, the flow of packages is diverted to the other supply point by means of a deflector, so that the full wire basket can be removed and an empty one moved into place.

Layout

Loading cage boxes


73

Exercise 11: Loading wire baskets

Parameters Material flow will be controlled by two valves with pushbutton, one for disabling and one for enabling. Due to the fact that the pushbutton signals are of short duration, a control system must be set up which stores the signal.

1. 2. 3. 4. 5. 6.

1. 2. 3. 4.

74

Project assignment Describe the mode of operation of a shuttle valve. Complete the pneumatic circuit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure When the pushbutton is activated, the cylinder advances and pushes the deflector into the flow of material. The cylinder remains in this position after the pushbutton has been released and the material flow is diverted. After activating the second pushbutton, the cylinder is retracted to the retracted end position and the material flow reverts to the original supply point. The cylinder remains in this position until the pushbutton is activated again.




Develop the required latching circuit and complete the circuit diagram shown below. 1A1

1V4

1V3

4

1

1

2

2

1V5

2

14 5 1V2

1

3

2

12 1 1S2

1 1V1 1 1S1

3

2

3

2 1

2

1

3



75


Mode of operation of a latching circuit –

Describe the mode of operation of a latching circuit. A latching circuit is used to convert a brief signal into a continuous signal. The valve group consisting of 1S1, 1S2, 1V1 and 1V2 is such a latching circuit. Activating pushbutton 1S1 causes a continuous signal at the output of valve 1V2.

If the pushbutton at valve 1S1 is activated, shuttle valve 1V1 allows compressed air to flow. As valve 1S2 is normally open, the compressed air actuates input 12 at 3/2-way valve 1V2. As a result, input 14 at 5/2way valve 1V3 is also actuated. Directional control valve 1V3 is reversed, and the cylinder’s piston advances. However, valve 1V2 is held in the actuated state at the same time by the return line to shuttle valve 1V1.

When 3/2-way valve 1S2 is actuated, the self-latching loop is interrupted. There’s no longer a signal at input 12 at valve 1V2, and the valve is switched to its normal position. Input 14 at 5/2-way valve 1V3 and the return line to the shuttle valve are exhausted. Valve 1V3 is switched to its normal position and the cylinder piston returns to its initial position. In the event that pushbuttons 1S1 and 1S2 are both activated at the same time, there’s no signal at the output either. This type of control system is called an RS flip-flop.

76



Create an equipment list –

Create an equipment list by entering the required components in the table below. Take all components into consideration that are required for the set-up.

Quantity

Designation

1


2


1

5/2-way valve, pneumatic, with spring return

1


1


1

3-2 way valve, pneumatic, normally closed

1

Shuttle valve (OR)

1

Distributor block

1

On-off valve with filter -regulator

1



77


78


Exercise 12: Actuating a sliding door Learning objectives After completing this exercise:  You’ll be able to combine logic operations.  You’ll be familiar with the set-up and mode of operation of a pneumatic proximity switch.  You’ll be able to differentiate between 5/2-way valves and select and use them in accordance with specifications.

Presentation of the problem A sliding door between two rooms needs to be opened and closed using a pushbutton. Only one pushbutton should be located at each side of the door in order to prevent operator error in case of an emergency.

Layout

Sliding door

© Festo Didactic GmbH & Co. KG

79

Exercise 12: Actuating a sliding door

 

Parameters Either process can only be started when the door is in one of its end positions. Pressure must be limited to 3 bar (300 kPa) for safety reasons (danger of pinching).

1. 2. 3. 4. 5.

Project assignment Create a pneumatic circuit diagram for the sliding door’s control system. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure When the sliding door is in one of its defined end positions, it can be moved to the other end position by pressing the pushbutton. The door can thus be opened and closed. The opening and closing processes cannot be started as long as the door is not in one of its end positions.

Safety note Limit pressure at the service unit to a maximum of 3 bar (300 kPa) for this exercise.

 

80

Additional tasks What happens if compressed air supply fails during advance or return motion? How can the control system be put back into operation, what must be done?



Mode of operation of a pneumatic proximity switch

S N

2

1

N S

3

Circuit symbol and schematic diagram of a pneumatic proximity switch

–

Describe the mode of operation of the pneumatic proximity switch. A pneumatic proximity switch is a 3/2-way valve which is actuated by a permanent magnet mounted on the piston of a cylinder. If the permanent magnet is in close proximity to the proximity switch, the 3/2way valve is actuated and generates a pneumatic signal. Proximity switches are mounted directly on the cylinder barrel.


81



Complete the circuit diagram shown below. 1A1 1B1

1V5

1V4

1B2

1

1

2

2

4

2

14

12 5

1V2

1V3 1

1V1

1

1S1

2

3

1

3

1

2

1B2

1

1S2

2

2

1

2

1

1B1

3

1

2

1

1V6

1

3

2

1

3


82



Create a sequence description –

Set up the control system and describe its working sequence. Initial position The cylinder is in the retracted end position. Pneumatic proximity switch 1B1 is actuated. A pneumatic signal is applied to one input of dual-pressure valve 1V2.

Step 1-2 If one of the two pushbuttons is activated, shuttle valve 1V1 generates an output signal. A signal is now applied to pilot port 14 at the 5/2-way double pilot valve and the valve is switched. The cylinder advances. When the cylinder reaches the advanced end position, pneumatic proximity switch 1B2 is attenuated.

Step 2-3 If one of the two pushbuttons is activated, shuttle valve 1V1 generates an output signal. A signal is now applied to pilot port 12 at the 5/2-way double pilot valve and the valve is switched. The cylinder is retracted. When the cylinder reaches the retracted end position, pneumatic proximity switch 1B1 is attenuated.


83



84


Quantity

Designation

1


2


1

5/2-way double pilot valve, pneumatic

2

Proximity sensor, pneumatic

2


2


1

Shuttle valve (OR)

1

Distributor block

1


1




Additional task: malfunction due to pressure failure Compressed air supply to the control system fails during forward or reverse motion of the sliding door. What happens, and how can the control system be placed back into service? –

Describe the consequences of a pressure failure and explain how the control system can be placed back into service. The door remains in its current position. It must be manually pushed into one of its end-positions in order to restart the control system, because otherwise the start condition is not fulfilled (door is in one of its two end-positions).


85


86


Exercise 13: Feeding wooden boards Learning objectives After completing this exercise you’ll:  Be familiar with the NOT operation.  Be able to combine logic operations.  Be able to further develop existing control systems.

Presentation of the problem Wooden boards need to be fed from a magazine to a machining process. Workpieces should not be pushed out of the magazine if the picking area is occupied.

Layout

Stacking magazine


87

Exercise 13: Feeding wooden boards



1. 2. 3. 4. 5.

Parameters A roller lever valve is used to mechanically determine whether or not a board is located in the picking area. The cylinder is throttled while advancing and retracting.

Project assignment Complete the pneumatic circuit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. The ejecting process is started by means of a pushbutton when the cylinder is in its retracted end position. The ejecting cylinder only pushes a workpiece out of the magazine when the roller lever valve in the picking area indicates that the picking area is NOT occupied. 2. If the picking area is empty, the cylinder advances to the advanced end position with restricted exhaust air, pushes the workpiece out and immediately returns to its retracted end position with restricted exhaust air.

Additional task How would you have to change the control system if the ejecting process could only start when a workpiece is in the magazine AND the picking area is empty?

88





1V4

1V3

1B2

1

1

2

2

4

2

14

12 5

1V2

1

1V1

2

1

1B1

2

1

3

3

1

2

1

1S1

1V5

1

1

1S2

2

3

1B2

2

1

3

2

1

3


Note You can use a 3/2-way valve with selector switch in the control system instead of a 3/2-way roller lever valve, if you want to simulate whether the picking area is empty or occupied.


89



Set up the control system and describe its working sequence. Initial position Compressed air is present. The cylinder is in the retracted end position. Pneumatic proximity switch 1B1 is attenuated and switched to the free-flow direction. The piston rod chamber is pressurised.

Step 1-2 If the picking area is occupied, 3/2-way roller lever valve 1S2 is not actuated. Dual-pressure valve 1V1 does not generate an output signal and the 5/2-way double pilot valve cannot be reversed. If the picking area is empty, 3/2-way roller lever valve 1S2 is actuated. Dual-pressure valve 1V1 generates an output signal. If the pushbutton at 3/2-way valve 1S1 is activated, dual-pressure valve 1V2 generates an output signal. A signal is applied to pilot port 14 at 5/2-way double pilot valve 1V3. The 5/2-way double pilot valve is reversed and the cylinder advances.

Step 2-3 Pneumatic proximity switch 1B2 is attenuated and switches to the free-flow direction. A signal is applied to pilot port 12 at the 5/2-way double pilot valve. 5/2-way double pilot valve 1V3 is switched and the cylinder travels to its retracted end position. Pneumatic limit switch 1B1 is attenuated and switches to the free-flow direction.

Step 3-1 Same as step 1

90





Quantity

Designation

1


2


1


2


1


1


2


1

Distributor block

1


1



91


Adapt the control system The control system must be changed so that the ejecting process can only be started when a workpiece is in the magazine AND the picking area is empty. –

Explain how the control system has to be changed in order to meet this requirement. An additional sensor will have to be connected for workpiece sensing. A suitable sensor is therefore required (roller lever valve) as well as a dual-pressure valve (AND). An AND operation will be added for the two sensors instead of using 3/2-way valve 1S2.

92


Exercise 14: Compacting beverage cans Learning objectives After completing this exercise:  You’ll be familiar with the set-up and mode of operation of a pressure sequence valve.  You’ll be able to set up pressure-dependent control systems.

Presentation of the problem Beverage cans are pressed into bales so that they take up minimal storage space at a recycling plant. The compacting process is started using a pushbutton. The return stroke can be triggered with another pushbutton. The compacting process should only be started when enough pressure is available.

Layout

Can press


93

Exercise 14: Compacting beverage cans

Parameters The initial position of the compacting cylinder is the retracted end position. The compacting process should only be started when system pressure is greater than 6 bar (600 kPa). The return stroke can be triggered manually if the compacting cylinder does not fully reach the advanced end position due to the quantity of cans to be compacted.

  

1. 2. 3. 4. 5.

Project assignment Complete the pneumatic circuit diagram for the can press. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. A pressure sequence valve is switched when the specified pressure value is reached and supplies compressed air to the control system. The control system should not be operable at a pressure of less than 4.5 bar (450 kPa). 2. It should only be possible to start the compacting process using a start button when the compacting cylinder is in the retracted end position. The compacting cylinder moves to the advanced end position or as far as it can depending on the amount of material to be compacted. 3. The return stroke is triggered either by a limit switch or a pushbutton.

Note The required protective guard is not shown.

94



Mode of operation of a pressure sequence valve

2

12

1

3

Circuit symbol for a pressure sequence valve

–

3 2 1

12

Schematic diagram of a pressure sequence valve

Describe the mode of operation of a pressure sequence valve. If pressure at pilot port 12 exceeds a certain adjustable value, the actuated 3/2-way valve is switched and compressed air is applied to working port 2. The 3/2-way valve switches back to its initial position when pressure at the pilot port drops back below the selected value.


95




1V6

1B2

1

2 1V5

2

4

2

14

12 5

1V3

1

1

3 1V4

2 1

1

1B1

1V7

1

1

1S1

2

1S2

2

1

3

1V2

1

1B2

2

1

3

2

3

2

1

3

2

12

1

3

1V1

2

1

3


96





Quantity

Designation

1


2


1


2


2


1


1

Shuttle valve (OR)

1


1

Pressure regulator valve with gauge

1

Distributor block

1


1



97


Sequence description Set up the control system and put it into operation. –

Describe the control system’s working sequence. Initial position The double-acting cylinder is in its retracted end position. Pneumatic proximity switch 1B1 is actuated and switched to the free-flow direction. Compressed air is present. The required pressure level has been pre-selected at the pressure regulator in the service unit. The desired pressure value has been set at the pressure sequence valve.

Step 1-2 The pushbutton at valve 1S1 is activated. The condition at dual-pressure valve 1V3 (AND) is changed to TRUE as a result. 5/2-way double pilot valve 1V5 is switched to the operating position. The double-acting cylinder advances.

Step 2-3 Pneumatic limit switch 1B2 is actuated and switches to the operating position. 5/2-way double pilot valve 1V5 is reset by shuttle valve 1V4 (OR). Alternatively, this process can be started using the pushbutton at valve 1S2. The 5/2-way double pilot valve is reset by shuttle valve 1V4 (OR). The double-acting cylinder returns to its initial position. The process is finished when pneumatic limit switch 1B1 is actuated.

98


Exercise 15: Packaging of brochures Learning objectives After completing this exercise:  You’ll be familiar with the set-up and mode of operation of a pressure regulator.  You’ll be able to set up pressure-dependent control systems.

Presentation of the problem Sets of 10 brochures each are to be wrapped in plastic film. The brochures have to be clamped in order for the film to seal properly. An operating pressure of at least 4 bar (400 kPa) is required in order to be able to clamp the brochures securely. However, the maximum operating pressure of 6 bar (600 kPa) should not be exceeded as otherwise the brochures risk being damaged. The advance and reverse strokes are triggered using a pushbutton. The retracted end position of the clamping cylinder is sensed via a pneumatic proximity switch.

Layout

Brochure production


99

Exercise 15: Packaging of brochures

  

Parameters The process can only be started when the clamping cylinder is in the retracted end position. The operating pressure has to be greater than 6 bar (600 kPa) before the control system can be started up. The return stroke is triggered manually, because the duration of the packaging process varies.

1. 2. 3. 4. 5.

Project assignment Complete the pneumatic circuit diagram for the packaging unit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. A pressure sequence valve is switched when the specified pressure value is reached and supplies compressed air to the control system. 2. The tensioning process starts when the clamping cylinder is in the retracted end position and a pushbutton is activated. The cylinder is advanced and remains in the advanced position. 3. The process ends when a second pushbutton is activated and the cylinder returns to the retracted end position.

100



Mode of operation of a pressure regulator

2

p1

p2

1 3

Circuit symbol for a pressure regulator

–

Schematic diagram of a pressure regulator

Describe the mode of operation of a pressure regulator. Input pressure (primary pressure) at the pressure regulator must always be higher than output pressure (secondary pressure). Pressure regulation itself takes place via a diaphragm. Output pressure acts on one side of the diaphragm and the force of a spring on the other. Spring force can be adjusted with an adjusting screw.

If pressure at the secondary side is increased, for example due to a load change at the cylinder, the diaphragm is pressed against the spring and the outlet cross-section of the valve seat is reduced or closed. The valve seat of the diaphragm is opened and compressed air is able to escape into the atmosphere through the relief ports in the housing.

If pressure drops at the secondary side, the valve is opened by the force of the spring. Thus regulating air pressure to the pre-selected operating pressure means that the valve seat is continuously opened and closed, which is triggered by the volume of air that flows through. Operating pressure is indicated by a measuring instrument.


101




1V7

1

2

1V6 1V5

1 2

2

1

1V4

4

3

2

14

12 5

1V3

2

1 1B1

1

1 1S1

2

3

1

1S2

2

1

3

1

3

1V2

1V1

2

3

2

12

1

3

2

1

3


102





Quantity

Designation

1


2


1


1


2


1


1


2

Pressure regulator (on-off valve with filter regulator).

1

Distributor block

1


1



103


Mode of operation of the one-way flow control valve –

Describe the function of the one-way flow control valve which is connected in parallel to the pressure regulator. One-way flow control valve 1V5 functions as a bypass for the pressure regulator. The flow control is fully closed. Compressed air can escape via the non-return valve when the cylinder is retracted, because it’s unable to escape via the pressure regulator.

104


Exercise 16: Mounting locking pins Learning objectives After completing this exercise you’ll:  Be able to set up pressure-dependent control systems.  Be able to analyse and optimise existing control systems.

Presentation of the problem Locking pins are to be mounted on plug connector housings at an automated assembly machine. So far, pressure has been set using a pressure regulator at the assembly machine. This has led to repeated malfunctions in the assembly process. The assembly process will now be examined using a test set-up. Each assembly step is triggered manually. The control system will be changed so that it only functions when pressure does not exceed a certain value.

Layout

Automated assembly machine for plug connector housings


105

Exercise 16: Mounting locking pins

Parameters Pressure at the working port of the assembly cylinder must have a value of at least 3.5 bar (350 kPa), in order to ensure that the locking pins are securely mounted. It should not be possible to start the process if pressure is greater than 3.8 bar (380 kPa). The return stroke of the assembly cylinder is started automatically when it reaches the advanced end position.

  

1. 2. 3. 4. 5.

1. 2. 3. 4.

Project assignment Complete the pneumatic circuit diagram for the automated assembly machine. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure The process will be started with a pushbutton when the assembly cylinder is in the retracted end position. The cylinder should move to the advanced end position with minimal force. It actuates a limit switch in this position. It should then quickly return to the retracted end position.

Analyse the pneumatic circuit diagram –

Analyse the circuit diagram shown below and determine whether or not it’s suitable for the required task. The circuit diagram is suitable.

–

What are the advantages or disadvantages of the characteristics of the required control system? There is a danger that pressure can be incorrectly set at the pressure regulator in the supply line to the cylinder which would result in the pins being damaged.

106



1A1 1B1

1V7

1

2

1V6 1V5

1 2

2

1

1V4

4

3

2

14

12 5

1V3

2

1 1B1

1

1 1S1

2

3

1

1S2

2

1

3

1

3

1V2

1V1

2

3

2

12

1

3

2

1

3



107



Complete the pneumatic circuit diagram shown below, taking all required conditions into consideration. 1A1 1B1

1V7

1B2

1

2 1V6

2

4

2

14

12 5

1V5

3

1

1V4

2

1

1

2

1

1V3

1V8

1

1

2

12 1 1V2

3

2

12

1

3

1V1

2 1B1

1S1

2

1B2

2 1

1

3

1

3

2

3 1

3


108





Quantity

Designation

1


2


1


2


1

3-2 way valve, pneumatic, normally open

1


2


1


1

Pressure regulator

1

Distributor block

1


1


Equipment list


109



Describe the control system’s working sequence. Initial position The double-acting cylinder is in its retracted end position. Pneumatic proximity switch 1B1 is attenuated. Compressed air is present. The desired pressure value has been set at the regulator and at the pressure sequence valve.

Step 1-2 Pushbutton 1S1 is activated and pneumatic proximity switch 1B1 is attenuated; the condition at the first dual-pressure valve, 1V3 (AND), thus becomes TRUE. After the pressure sequence valve has been switched with sufficient pressure, the 3/2-way valve is switched to the operating position. The condition at the second 2-way valve, 1V5 (AND), thus becomes TRUE and the 5/2-way double pilot valve is switched to the operating position. The double-acting cylinder advances.

Step 2-3 Pneumatic proximity switch 1B2 is attenuated and switches to the operating position. The 5/2-way double pilot valve is switched. The double-acting cylinder returns to its initial position. The process is finished when pneumatic proximity switch 1B1 is attenuated.

110


Exercise 17: Labelling paint pots Learning objectives After completing this exercise you’ll:  Be able to set up time-dependent control systems.  Be familiar with the set-up and mode of operation of a time delay valve.

Presentation of the problem Paint pots are labelled at a gluing machine. The gluing process is triggered using a pushbutton at the machine. A drying time of approximately 10 seconds is required for the adhesive to become effective. The system is not ready to start until the piston of the pressing cylinder is in the retracted end position.

Layout

Farbe rau lichtg 35 0 RAL 7

Farbe au lichtgr 35 RAL 70

Labelling fixture


111

Exercise 17: Labelling paint pots

  

Parameters As the label has to be glued to the paint pot with minimal pressure, working pressure must be adjustable. The cylinder should be retracted as quickly as possible. Working pressure must be adjustable within a range of 3 to 7 bar (300 and 700 kPa). Pressure should be indicated by a pressure gauge upstream of the cylinder.

1. 2. 3. 4. 5.

Project assignment Complete the pneumatic circuit. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.



1. 2. 3. 4.

112

Procedure The process will be started using a pushbutton when the cylinder is in the retracted end position. The cylinder should advance to the advanced end position with minimal force and speed and remain in this position for an adjustable period of time. It should then quickly return to the retracted end position. Pressure during the forward stroke should be indicated at a pressure gauge.



Mode of operation of a time delay valve 2 t 1

3

Circuit symbol for a time delay valve

–

Describe the mode of operation of a time delay valve and enter the most important technical data in the table. The time delay valves switches input pressure applied to port 1 to port 2 after the preset delay time has expired. If the supply of compressed air is interrupted at port 1, working port 2 is once again switched to the unpressurised state. The time delay valve is automatically reset within 200 ms. Delay time is infinitely adjustable via an adjusting knob.

Technical data Pressure range

2 to 6 bar (200 to 600 kPa)

Switch-on pressure

> 1.6 bar (160 kPa)

Standard nominal flow rate

50 l/min.

Delay time

2 to 30 sec. (adjustable)

Setting accuracy

±0.6 sec.

Pause period for reset

> 200 ms


113




1B2

1Z1

1V6

2

1

3 1V5

2

1 1V4

4

2

14

12 5

1V2

1

3 1V3

2

1

2

1 t 1V1

1

3

2 1B1

1S1

2

1B2

2 1

1

3

1

3

2

3 1

3


114





Quantity

Designation

1


1


1

Quick exhaust valve

1


2


1


1

Time delay valve

1


1


1

Pressure gauge

1

Distributor block

1


1


Equipment list


115



Set up the control system and describe its working sequence. Initial position The double-acting cylinder is in its retracted end position. Pneumatic proximity switch 1B1 is attenuated. Compressed air is present. The required pressure value has been set at the pressure regulator.

Step 1-2 Pushbutton 1S1 is activated and pneumatic proximity switch 1B1 is attenuated; the condition at the first dual-pressure valve, 1V2 (AND), thus becomes TRUE and 5/2-way double pilot valve 1V4 is switched to the operating position. The double-acting cylinder is advanced with minimal pressure and with flow control.

Step 2-3 Pneumatic proximity switch 1B2 is attenuated and switches to the operating position. Compressed air is fed to time delay valve 1V3 as a result, which then switches through after a preset period of time. The 5/2-way double pilot valve is reset. The double-acting cylinder returns to its initial position with minimal pressure. The piston chamber is vented via the quick exhaust valve. The process is finished when pneumatic proximity switch 1B1 is attenuated.

116


Exercise 18: Cleaning workpieces Learning objectives After completing this exercise you’ll:  Be able to set up control systems with oscillating motion.  Be able to use time delay valves in accordance with specific constraints.

Presentation of the problem A wire basket with workpieces needs to be moved up and down in a cleaning bath. The process is started using a pushbutton.

Layout

Automatic cleaning system


117

Exercise 18: Cleaning workpieces

 

Parameters A roller lever valve will be used in order to detect the retracted end position. The cleaning process should be limited to a period of 20 seconds.

1. 2. 3. 4. 5. 6.

Project assignment Convert a 5/2-way double pilot valve to a 3/2-way double pilot valve. Complete the pneumatic circuit diagram for the automatic cleaning system. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

Procedure 1. The process is started using a pushbutton when the lifting cylinder is in its retracted end position. 2. The cylinder for the lifting device moves to the advanced end position. It then goes back to the midposition and returns to the advanced end position. This motion sequence is repeated until the process is stopped by the time delay valve. 3. The cylinder then returns to its retracted end position.

118



Convert a 5/2-way double pilot valve 4

2

14

12 5

1

3

Circuit symbol for a 5/2-way double pilot valve

– –

Convert a 5/2-way double pilot valve to a 3/2-way double pilot valve. Describe what has to be done. Output 4 is closed using a blanking plug.


119



Complete the circuit diagram shown below. 1B1 1B3

1B2

1A1

1

1V6

2 1V5

1

2 1V4 4

2

14

12 5

1V3

3

2 1

1 1B1 2

1

1

1B3

1B2 2

2

1

3

1

3

3

1V2 2 10

12 1

1V1

3 1S1

2

2

t 1

3

1

3

Pneumatic circuit diagram (solution)

120




Set up the control system and describe its working sequence. Initial position In the initial position, the cylinder is in its retracted end position and it actuates 3/2-way roller lever valve 1B1. Final control element 1V4 (5/2-way double pilot valve) is advanced to the right switching position. Signal latch 1V2 (3/2-way double pilot valve) is also in the right switching position. The required pressure value has been set at the pressure regulator.

Step 1-2 After activating start button 1S1, signal latch 1V2 is switched. Compressed air is fed to the input at time delay valve 1V1. The 5/2-way double pilot valve 1V4 is switched by 3/2-way roller lever valve 1B1 and shuttle valve 1V3 (OR) and the cylinder is advanced. Travel beyond pneumatic proximity switch 1B3 at the mid-position has no effect, because the same control port of the final control element is actuated.

Step 2-3 Pneumatic proximity switch 1B2 is actuated in the advanced end position. The final control element (5/2way double pilot valve) is switched. The cylinder is retracted and actuates pneumatic proximity switch 1B3 at the mid-position.

Step 3-4 The cylinder is once again reversed when pneumatic proximity switch 1B3 at the mid-position is actuated. Reversing only takes a few milliseconds, and thus the trip cam does not travel beyond pneumatic proximity switch 1B3.

Step 4-5

See step 2-3.

Oscillating motion The cylinder moves back and forth between pneumatic proximity switches 1B3 and 1B2 until time specified at time delay valve 1V1 has elapsed.

Steps n-2 through n After the time delay valve has switched through, signal latch 1V2 (3/2-way double pilot valve) is reversed. Pneumatic proximity switch 1B3 and 3/2-way roller lever valve 1B1 are no longer supplied with compressed air. The cylinder travels to its initial position (retracted end position). The process is finished when 3/2-way roller lever valve 1B1 is actuated.


121




Quantity

Designation

1


2


1


1


2


1


1


1

Time delay valve

1

Shuttle valve (OR)

1

Distributor block

1


1


Note A pneumatic 5/2-way double pilot valve is converted to a pneumatic 3/2-way double pilot valve.

122


Exercise 19: Pressing labels into place Learning objectives After completing this exercise you’ll:  Be able to analyse and set up control systems with two cylinders.

Presentation of the problem Rating plates are pressed into valve housings at a workstation. First of all, the labels are inserted into recesses in the valve housings. Then they’re pressed into place with a pressing cylinder. The valve housings are clamped by pressing a pushbutton. The pressing process is started once the valve housing has been clamped. Both cylinders should be retracted after the pressing cylinder has reached its advanced end-position.

Layout

Labelling fixture


123

Exercise 19: Pressing labels into place

 

Parameters A single-acting cylinder will be used to clamp the valve housings. A roller lever valve will be used to detect whether or not the clamping cylinder has reached its advanced end position. A double-acting cylinder will be used as a pressing cylinder. The feed speeds of both the clamping and the pressing cylinders should be adjustable.

1. 2. 3. 4. 5.

Project assignment Analyse the pneumatic circuit diagram for the pressing fixture. Set up the control system. Double-check the control system configuration. Describe the mode of operation of the control system. Create an equipment list.

 

1. 2. 3. 4.

Procedure The pressing process is started using a pushbutton. A limit switch will be used to detect whether or not the clamping cylinder has reached its position. The pressing cylinder should not advance until the clamping cylinder has reached its advanced end position. After the plastic cap has been pressed into place, both cylinders are retracted.

Note Necessary protective guards are not taken into consideration.

124





1A1

1V3

2V2

2

1

1 1V2

2 2V1

2

12

10 1

1V1 1

1S1

1

3

4

2

14

3

12 5

1

3

2 1

1B2

2B1 2

2

2B2

1B2

1

3

2B2

2

1

3

2

1

3



125




Quantity

Designation

1


1


2


1


1


2


1


1


1


1

Distributor block

1


1


Equipment list

Note A pneumatic 5/2-way double pilot valve is converted to a pneumatic 3/2-way double pilot valve.

126




Set up the control system and describe its working sequence. Initial position Pressure is present. In the initial position, both cylinders are in the retracted end position. The piston in the double-acting cylinder attenuates pneumatic proximity switch 2B1, which is switched to the free-flow direction. Final control elements 1V2 and 2V1 (5/2-way double pilot valve and 3/2-way double pilot valve) travel to the right switching position.

Step 1-2 When pushbutton 1S1 is activated, the condition at dual-pressure valve 1V1 (AND) becomes TRUE. The 3/2-way double pilot valve 1V2 is reversed. The single-acting cylinder advances with restricted supply air.

Step 2-3 When the single-acting cylinder reaches its advanced end position, roller lever valve 1B2 is actuated and reverses 5/2-way double pilot valve 2V1. The double-acting cylinder moves to its advanced end position where it attenuates pneumatic proximity switch 2B2, which is switched to the free-flow direction.

Step 3-4 5/2-way double pilot valve 2V1 and 3/2-way double pilot valve 1V2 are reversed. Both cylinders are retracted. The process is finished when the piston in the double-acting cylinder attenuates pneumatic proximity switch 2B1, which then switches to the free-flow direction.

Note Single-acting cylinder 1A1 is retracted slightly earlier than double-acting cylinder 2A1. This is due to overlapping of the control signals at pilot ports 14 and 12 at 5/2-way double pilot valve 2V1. The 5/2-way double pilot valve 2V1 can only reverse when single-acting cylinder 1A1 has left its advanced end position and 3/2-way roller lever valve 1B2 is no longer actuated.


127


Proximity switch failure What happens if the position of pneumatic proximity switch 1B2 is shifted along the cylinder? –

Make a note of the resulting consequences. Pneumatic proximity switch 1B2 is not attenuated and the 5/2-way double pilot valve and the 3/2-way double pilot valve are thus no longer reset. The cylinder no longer returns to the retracted end position. As a result, proximity switch 1B1 is not attenuated and the control system can no longer be started.

128


541088 Workbook Pneumatics Basic Level

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