EE061 Pneumatic Controls Pr Inst

SRI LANKA INSTITUTE of ADVANCED TECHNOLOGICAL EDUCATION

ELECTRICAL and ELECTRONIC ENGINEERING Instructor Manual

Training Unit

Pneumatic neumatic Contr on trols ols Practice

No: EE 061

Training Unit Pneumatic neumatic Controls Contr ols

Practical Part No.: EE 061

Edition:

2009 Al l Righ Ri ghts ts Reserved Reser ved

Editor:

MCE MCE Industrietechnik Linz GmbH & Co Education and Training Systems, DM-1 Lun zerstrass e 64 P.O.Box P.O.Box 36, A 4031 Linz / Au str ia Tel. (+ 43 / 732) 6987 – 3475 Fax (+ 43 / 732) 6980 – 4271 Website: Website: www.mcelinz.com www.mcelinz.com 1

PNEUMATIC CONTROLS LIST OF CONTENT

CONTENTS

Page

Introduction ....................... ........................... ......................... ........................... ..................... 4 General Information...........................................................................................................4 Safety ......................... ........................... ......................... ......................... .......................... 6 Performing Exercises .......................... ......................... ......................... ........................... .6 Commissioning..................................................................................................................7 Exercise 1

Direct control of a single-acting single-acting cylinder, cylinder, extending ........................ .............. 9

Exercise 2

Direct control of a single-acting cylinder, retracting.....................................11

Exercise 3

Indirect control control of of a single-acting cylinder .......................... ......................... 14

Exercise 4

Regulating the speed of a single-acting cylinder.........................................17

Exercise 5

Slow-speed extension, rapid rapid retraction of a single-acting cylinder.............. 20

Exercise 6

Direct control of a double-acting cylinder with push-button.........................23

Exercise 7

Indirect control of a double-acting cylinder..................................................26

Exercise 8

Speed regulation of a double-acting cylinder .......................... .................... 28

Exercise 9

Controlling a double-acting double-acting cylinder, impulse valve, 2 push-buttons........... 31

Exercise 10

Displacement-dependent Displacement-dependent control of a double-acting cylinder, impulse valve ..

.....................................................................................................................34

Exercise 11

Controlling a double-acting double-acting cylinder, impulse valve, 2 reflex nozzles.......... 37

Exercise 12

Stop control, double-acting cylinder with 5/3 directional control valve, tensile

load

.....................................................................................................................41

2

Exercise 13

Pressure-dependent Pressure-dependent control of 1 double-acting double-acting cylinder ...................... .......45 ....... 45

Exercise 14

Time-dependent Time-dependent control of 1 double-acting cylinder.................................... 49

Exercise 15

Logical control with shuttle and twin-pressure valves..................................53

Exercise 16

Sequential control of 2 double-acting cylinders without overlapping signals...

.....................................................................................................................57

Exercise 17 Sequential control of 2 double-acting cylinders with signal overlapping, rollers with idle return.....................................................................................................................61 Exercise 18

Sequential control of 2 double-acting cylinders with signal overlapping,

change-over valve...............................................................................................................65

3

Introduction

General Information The exercises to be found in this brochure "Rexroth Practice for Professionals Pneumatics" correspond to the exercises of "Übungsreihe Pneumatik" [Training series "Pneumatics"] published by the Bundesinstitut für Berufsbildung (Federal Institute for Vocational Training) in Berlin. The exercises were extended in respect to the technological further developments in pneumatic control technology and new exercises were added to the practice series. For practical exercises, a practice System and the basic kit for pneumatics under the BIBB order number 0827 003 365 are available. In order to achieve the best practical results, the basic kits include only industrial components. The components are equipped with a patented "Snap-in" system and can be easily and quickly attached to the base plate by the user in the exercises. The following features characterize the practice system: -

The base plate is a grooved plate. lt provides provides the advantage of being able to position the components infinitely and allows a variable arrangement on the plate.

-

The grooved grooved plate can be used horizontally horizontally on a lab table to do practical exercises. The air service unit can be tilted to a 45 degree angle and thus can be optimally mounted on the horizontal plate.

-

The mobile "DS3 synergy" synergy" system uses various various table table and and accessory accessory modules modules to create various set-ups.

-

The grooved grooved plate can can also be used used in a vertical vertical or tilted position. position.

-

The "Snap-in" "Snap-in" system system allows all components components to be easily easily attached and in some cases be turned at a 90 degree angle. In this manner the space on the plate can be used more effectively.

-

Valves of various nominal nominal sizes with quick-release quick-release coupling coupling attached attached are used. The elements are connected by plastic tubes of the same diameter.

-

All cylinders used have have a piston diameter diameter of 25 mm. Single-acting cylinders have a stroke length of 50 mm, the double-acting cylinders of 100 mm and are spring cushioned. 4

-

For exercises exercises in connection with electro-pneumatic electro-pneumatic components, the double-acting double-acting cylinders are equipped with proximity switching through an annular magnet encapsulated in the piston.

Base plate plate and basic kit for th e practical exercises exercises

Description

Order No.

Grooved plate LT

0 827 003 702

Basic kit Pneumatics BIBB

0 827 003 365

Optional Equipment and Accessories

Description

Order No.

DS3 Basic frame

0 827 003 701

Grooved plate ERGO

0 827 003 717

Mobile file

0 827 003 707

Writing support

0 827 003 705

Information board (A4-sheet holder)

0 827 003 721

5

Safety In general there are no real dangers when doing exercises with pneumatic components. Nevertheless, all piping work should principally be executed with the air pressure turned off (ball valve an the air-service unit should be closed). Please regard the following measures in any case: -

The locking locking plugs plugs on the quick-release quick-release couplings of distributor distributor and and components components should be properly secured!

-

Plastic tubes that come loose from quick-release quick-release couplings when pressure is applied applied have a "lashing effect" (protect eyes!).

-

When detaching detaching tubes under pressure, pressure, use one hand to press the release ring and the other to pull out the end of the tube, holding it tightly.

-

lt is possible possible that cylinders will independently start to move when turning on the air pressure.

-

Do not try and touch any moving parts parts (piston rod, switching cam). This could cause painful injuries by pinching your finger between the limit switch and switching cam.

Performing Exercises

-

For optimum, synergetic and successful learning within a reasonable reasonable exercise time, two students should work together at a practice unit at a time.

-

The equipment equipment to be used is listed in the equipment list in the instructions. instructions.

-

The arrangement arrangement of the equipment on the base plate plate should be executed executed according according to the arrangement sketch that goes with each exercise.

-

The components components are attached by by snapping them properly properly onto the grooves grooves in the grooved plate.

-

The exercise exercise is to be circuited according to the circuit diagram diagram with plastic tubes and Tdistributors.

-

The plastic plastic tubes are to be stuck into the quick-release quick-release coupling coupling with light pressure. pressure. To detach the tubes, briefly press the release ring with one hand and remove the tube with the other.

-

Note: to avoid the plastic tubes from getting stuck, frequently cut off the end of the tube with the tube cutter. 6

-

Pay attention to optimum error detection: detection: when an error occurs, do not not pipe the exercise again, even in the most complicated circuits that are already mounted, but rather use the systematic error analysis to find the error and eliminate it.

-

Further notes an an executing executing the exercises, as well as written and graphic graphic evaluation can be found in the instructions in each description.

Commissioning

-

For each exercise unit, unit, a pressure pressure supply of 6 to 8 bar, without lubrication, lubrication, should be available, with a suction capacity of 50 to 100 NI/min.

-

The system pressure at the work-place should be be set an the air regulator regulator as a standard standard of pe = 5 bar.

-

All piping work should be carried carried out without pressure pressure (ball valve an the air service unit should be closed).

-

Any air escaping through open quick-release couplings or from from plastic tubes causes causes a drop in pressure, especially when several workplaces with relatively low supply capacity and insufficient storage volume are in operation.

7

Basic Kit Pneumatics BIBB Order No. 1 82700 827003 3 365, 365, Lis t of Com ponent s Qty.

Descriptio n

1

Air service unit with 3/2 directional control ball valve, G1/8, 0.5 - 10 bar 1 Distributor, 6-fold, self-closing couplings 1 Cylinder, single-acting single-ac ting with return spring, Ø = 25 mm, stroke = 50 mm 3 Cylinder, double-acting, double-acting, with adjustable spring cushioning and for proximity switching, Ø = 25 mm, stroke = 100 mm 1 Cylinder, double-acting double-acting with adjustable spring cushioning and for proximity switching, Ø = 25 mm, stroke = 100 mm, with an attachment for tensile load 3.4 kg 2 3/2 directional directiona l control valve M5, manually operated with pushbutton, closed neutral position 1 3/2 directional control valve G1/8, manually operated with push-button, flow in both directions 1 5/2 directional control valve G1/8, manually operated with push-button 1 3/2 direct. control valve G1/8 with restoring spring, pneum. operated, flow in both directions 1 5/2 directional directiona l control valve G 1/8 with restoring restorin g spring, pneumatically operated 3 5/2 directional direction al control impulse valve G1/8, pneumatically operated 1 5/3 directional control valve G1/8, pneumatically pneumatically operated, mid-position closed 4 3/2 directional control valve M5, mechanically mechanically operated, roller, closed neutral position 2 3/2 direct. control valve M5, mech. operated, idle return roller, closed neutral position 2 Flow control valve with non-return non-retur n G1/8, hose version 1 Quick-exhaust valve G1/4 1 3/2 directional control time delay valve, G1/8, flow in both directions, 0.15 - 55 s 2 Shuttle valve (OR) G 1/8, 1-fold 5 Twin-pressure valve (AND) G 1/8, 1-fold 1 Pressure display, pneumatic, pneumatic, red, minimum minimum pressure 1.2 bar 3 Pressure gauge 0 - 10 bar 1 Pressure switch with 3/2 directional control valve function, adjustable 2-8 bar 1 Pressure control valve with pressure gauge, G1/8, 0.5 - 10 bar 1 Pressure control valve for low pressure, with pressure gauge, G1/8, 0 - 1 bar 2 Reflex nozzle, min. pressure, 0.4 bar 2 3/2 amplifi amplifier er for reflex reflex nozzle, nozzle, 2-stage, 2-stage, G 1/8, X=12 - 500 mbar 1 Step sequence for 4 steps and check step, M5 25 Blanking plug, tube diameter 4 mm 5 Two-way plug, tube diameter 4 mm 5 T-connection for plastic tubing 4 mm 25m Plastic tubing 4 x 1; calibrated on the outside, PU black 2m Plastic tubing 6 x 1; calibrated on the outside, PU black 1 Tube cutter for plastic tubes

8

Order No.

Comp . No.

1 827 003 410

1

1 827 003 411 1 827 003 371

2 3

1 827 003 372

4

1 827 003 373

5

1 827 003 392

6

1 827 003 393

7

1 827 003 396

8

1 827 003 374

9

1 827 003 376

10

1 827 003 377

11

1 827 003 378

12

1 827 003 399

13

1 827 003 401

14

1 827 003 379 1 827 003 381 1 827 003 385

15 16 17

1 827 003 382 1 827 003 383 1 827 003 409 1 827 003 406 1 827 003 388

18 19 20 21 22

1 827 003 386 1 827 003 387

23 24

1 827 003 403 1 827 003 389 1 827 003 390 1 823 105 006 1 823 391 629 1 823 381 043 1 820 712 010 1 820 712 012 1 827 391 390

25 26 27 -------------

Exercise 1 Direct contr ol of a single-acting cylin der, extending

Ai m

This exercise provides basic know-how and skills on the set-up and operation of pneumatic controls using the control of a single-acting cylinder as an example. Suggestion for the positi oning of equipment on the workin g plate

Pneumatic Pneumatic circ uit diagram

List of equipment

Pos. 01

02 03 06

21

Qty. Description 1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve 1 Distributor, 6-fold 1 Single-acting cylinder 1 3/2 directional control valve with manually operated push-button 1 Pressure gauge Accessories

9

Task

-

The piston rod of the single-acting single-acting cylinder cylinder (Z1) should extend extend after the button (S1) has has been actuated and remain extended as long as the button is pushed.

-

The active pressure that is placed on on the cylinder piston piston should appear on the pressure gauge.

-

The pressurized pressurized air is supplied by by an air service unit (filter with water water separator, separator, pressure regulator and shut-off valve) and by the compressed-air distributor.

-

The circuit diagram is to be be drawn or additions additions made using symbols symbols and port symbols according to ISO 1219 and RP68P.


-

The piston rod of the single-acting single-acting cylinder cylinder Z1 extends after pushing the the button S1 and remains in that position as long as the button is pushed.

-

A pressure pressure gauge registers the active pressure pressure on the cylinder piston.

Didactic notes

-

This simple exercise helps helps get the student acquainted with the practical use use of the practice unit and components.

-

The student student performs performs the proper setting of the working pressure on the air service service unit and practices the use of plastic tubes and quick-release couplings.

-

Before starting starting the first exercise, the participant participant should should be informed of the procedure as well as the security measures involved.

Instructions

-

The arrangement arrangement of the equipment equipment on the working plate should be as shown in the arrangement sketch.

-

The working pressure of pe = 5 bar is to be set at the pressure regulator of the air service unit.

-

The components components are to be connected with plastic plastic tubes and accessories accessories according according to the circuit diagram.

-

The working pressure is switched on with the ball valve.

-

The exercise is started and the proper function is checked.

Conclusion

A single-acting cylinder can basically only be controlled with a 3/2 directional control valve. Corresponding to the basic position of the single-acting cylinder (piston rod retracted) a 3/2 directional control valve in locked, neutral position (n.c. = normally closed) should be mounted. 10

Exercise 2 Direct contr ol of a single-acting cylin der, retracting

Ai m

This exercise demonstrates the use of a 3/2 directional control valve with flow in both directions functioning as an open neutral position valve of a single-acting cylinder extended in neutral position. Suggestion for the positi oning of equipment an the working plate


List of equipment

Pos. 01

Qty. 1

02 03

1 1

07

1

Description Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve Distributor, 6-fold Single-acting cylinder 3/2 directional control valve with manually operated pushbutton, flow in both directions Accessories 11

Task

-

The basic position of the piston rod of the single-acting single-acting cylinder cylinder (Z1) is extended extended after switching on the compressed air supply.

-

After actuating actuating the push-button (S1) the piston of the single-acting single-acting cylinder cylinder should retract and remain retracted as long as the button S1 is pushed.

-

The pressurized pressurized air is supplied by by an air service unit (filter with water water separator, separator, pressure regulator and shut-off valve) and by the pressure distributor.

-

The circuit diagram is to be be drawn or additions additions made using symbols symbols and port symbols according to ISO 1219 and RP68P.


-

After switching on the pressure by opening opening the 3/2 directional directional control ball valve, the piston of the single-acting cylinder extends.

-

After pushing pushing the button S1 S1 (3/2 directional control valve), valve), the piston rod of the singleacting cylinder Z1 retracts and remains retracted as long as the button S1 is pushed.

Didactic notes

-

In addition addition to the 2 types of seat constructions constructions for 3/2 directional directional control valves, closed neutral position or open neutral position, the spool valve design is also available.

-

One advantage advantage of the spool spool valve is that the valve principally allows "flow" in both directions.

-

This type of valve can therefore therefore be applied in an open neutral position or also in the closed neutral position.

-

Technical notice referring referring to the equipment: equipment: the designation of symbols for ports ports for spool valves with flow in both directions is often found in different manners: in some cases only the symbol indicates this design, but often the ports are marked with 1/3 or 3/1 or 1 (3) or 3 (1).

-

In the case of servo valves, valves, a mechanical alteration is often necessary (for example example twisting the servo head) in addition to exchanging the two ports 1 and 3.

-

In the circuit diagram diagram the solution solution with a manually manually operated operated 3/2 directional directional control valve in open neutral position is to be considered as correct.

Instructions

-


-

The working pressure of pe pe = 5 bar is to be set at the pressure regulator of the air service unit. 12

-

The components components are to be piped according to the circuit diagram diagram with plastic tubes and accessories.

-


-

The exercise is started and the proper function is controlled.

Conclusion

In addition to the 3/2 directional control valves in closed neutral position (or n.c.) there are also directional control valves with open neutral position , (n.o. normally open). When a pneumatic circuit diagram is marked as "pressure-free" (3/2 directional control ball valve on "off"), then the cylinder also must be pictured in the pressure-free condition, i.e. the piston rod is retracted .

13

Exercise 3 Indirect contr ol of a single-acting cylind er

Ai m

This exercises conveys know-how on the indirect control of cylinders, using a single-acting cylinder and a pneumatically operated 3/2 directional control valve as an example. Suggestion for the positi oning of equipment on the workin g plate


List of equipment

Pos. 01

Qty. 1

02 03

1 1

06

1

09

1

Description Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve Distributor, 6-fold Single-acting cylinder 3/2 directional control valve with push-button, closed neutral position Pneumatically operated 3/2 directional control valve, closed neutral position Accessories

14

Task

-

The piston rod of a single-acting single-acting cylinder (Z1), retracted in neutral position, should should advance after pushing an easily pressed button (S1).

-

Note: for the the control of a large-volume large-volume cylinder cylinder (with a large piston piston diameter) diameter) an accordingly dimensioned directional control valve is necessary.

-

The cylinder is mounted mounted a slight slight distance distance from from the button button (S1).

-

After releasing releasing the manual push-button, push-button, the piston of the cylinder should retract retract automatically into its back position.

-

Additions to the circuit diagram.

-

All connections connections should should be marked with the port symbols symbols according according to ISO 5599 5599 or RP 68 P.


-

A manually manually operated operated 3/2 directional directional control control valve in closed neutral position (start button S1) applies pressure to a pneumatically operated 3/2 directional control valve.

-

A large volume single-acting cylinder is controlled via a pneumatically operated 3/2 directional control valve (pos. 9), the piston rod extends.

Didactic notes

-

Basic knowledge knowledge of the dimensioning dimensioning of of pneumatic pneumatic components components is a prerequisite for understanding this exercise.

-

lt should be pointed pointed out that in practice it is necessary to use plastic tubes of different dimensions and colors.

-

Circuit diagram: diagram: control control lines are the connecting lines between between the output of of signalling elements (for example button S1) and the pneumatic actuation ports of the actuators (for example pneumatically operated 3/2 directional control valve, port 12). These connecting lines are to be drawn as dotted lines.

-

The air pressure line to the signalling signalling elements is also also often often dotted. dotted.

-

Note: therefore therefore it is especially important that the participants understand the topics "servo valves" and "indirect control of cylinders" and do not confuse the two.

-

The main main reason reason for using indirect indirect control control in pneumatics: large volume, single-acting single-acting cylinders should be able to be controlled with a small dimensioned directional control valve at acceptable working speed. In addition, the button can also be mounted somewhat farther away from the cylinder (for example a button built into a control panel).

15

Instructions

-


-

The working pressure of pe pe = 5 bar is to be set at the pressure regulator of the air service unit.

-


-


-

The exercise is started and the proper function is controlled.

Conclusion

Large volume cylinders cannot be directly controlled with small-dimensioned directional control valves. These cylinders are therefore indirectly controlled through the installation of pneumatically operated operated 3/2 directional cont rol valves in a size corresponding to the cylinder size.

16

Exercise 4 Regulating Regulating the speed of a single-acting cylinder

Ai m

This exercise demonstrates the application of a one-way flow control valve to infinitely adjust the speed of a s ingle-acting cylinder. Suggestion for the positi oning of equipment an the working plate


List of equipment

Pos. Qty. Description 01 1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve 02 1 Distributor, 6-fold 03 1 Single-acting cylinder 07 1 3/2 directional control valve with pushbutton, closed neutral position 15 1 Flow control valve with non-return, adjustable 21 2 Pressure gauge Accessories

17

Task

-

The extension extension speed speed of the piston rod of a single-acting single-acting cylinder cylinder (Z1), (Z1), retracted in its neutral position, should be infinitely adjustable.

-

The retraction retraction of the the piston rod occurs at normal speed. The retraction speed speed is not not adjustable.

-

The cylinder cylinder is controlled with a manually operated button (S1). (S1). After releasing the button, the piston of the cylinder should retract automatically into its back position.

-


-

All connections connections should should be marked with the connection symbols according according to ISO 5599 5599 or RP 68 P.

Pneumatic Pneumatic cir cuit d iagram

-

A single-acting single-acting cylinder Z1 is directly controlled controlled via a pneumatically pneumatically operated operated 3/2 directional control valve (S1).

-

A flow control valve valve with non-return is built into the working line line between between the cylinder and the control valve which enables the piston rod to extend with infinitely adjustable speed and to retract with normal speed (through spring force).

-

The flow flow control valve with non-return is mounted mounted in such a way that the air flowing into the cylinder is restricted (supply air restriction).

-

Two pressure pressure gauges gauges indicate the pressure pressure before and alter alter the flow control control valve with non-return.

Didactic notes

-

If there is no port symbol symbol on the flow control valve valve with non-return, then the direction of of the symbol on the valve is considered that of the flow control valve with non-return. That is the reference for the correct mounting of the element.

-

If the flow control control valve with non-return non-return is closed all the way or otherwise blocked blocked (particles in the throttle) then the cylinder can only retract but not extend.

Instructions

-


-

The working pressure of pe pe = 5 bar is to be set at the pressure regulator of the air service unit.

-


18

-

The knurled-head knurled-head screw on the flow control valve valve with non-return should be be unscrewed unscrewed as far as possible (counter-clockwise).

-


-

Actuate S1, observe the retraction and extension speeds.

-

When frequently frequently changing changing the setting of the flow control control valve with non-return, non-return, observe both speeds (when retracting and extending) as well as the pressure on both pressure gauges.

Conclusion Flow control valves with non-return are used to achieve infinitely adjustable speed

regulation of the piston rod movement. The flow control valves with non-return are mounted in the working lines between the directional control valve and cylinder . For a single-acting cylinder the supply air restriction is used for the extending movement.

19

Exercise 5 Slow-speed Slow-speed extension, rapid retraction retraction of a single-acting cylinder

Ai m

In addition to throttling the cylinder speed, this exercise shows how to achieve the highest possible speed when retracting the piston rod by using a quick-exhaust valve. Suggestion for the positi oning of equipment an the work ing plate


List of equipment

Pos. Qty. Description 01 1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve 02 1 Distributor, 6-fold 03 1 Single-acting cylinder 07 1 3/2 directional control valve with pushbutton, closed neutral position 15 1 Flow control valves with non-return, adjustable 16 1 Quick-exhaust valve Accessories

20

Task

-

The piston rod of a large volume, single-acting single-acting cylinder cylinder (Z1) (Z1) is to extend with restricted, adjustable speed.

-

The retraction retraction of of the piston rod rod should should occur occur at the highest highest possible possible speed, speed, also when the directional control valve (S1) is mounted a distance away from the cylinder.

-

The cylinder cylinder is controlled by by a manually manually operated operated button button (S1). After releasing releasing the button, the piston rod should retract automatically into its back position.

-


-



-

Via the flow control control valve with non-return non-return mounted in the working line the speed of the piston rod when extending can be infinitely restricted.

-

Through the quick-exhaust quick-exhaust valve, also mounted mounted in the working line (as near to the cylinder port as possible), the cylinder piston retracts with the maximum possible speed.

Didactic notes

-

In practice, the valves are screwed screwed directly directly on to the cylinder port port with a double double nipple (with the exception of miniature quick-exhaust valves for tubes with a diameter less than 3 mm).

-

Depending on the diameter of the cylinder and and the piston piston rod speed, a loud exhaust exhaust noise can be heard when pressure is released from the quick-exhaust valve. An exhaust silencer should be available in such cases to protect those persons working there.

-

Quick-exhaust valves valves are also used in cases where where pressure pressure needs to be quickly released (for example they are installed in pneumatic two-hand safety controls).

Instructions

-


-


-

The knurled-head knurled-head screw on the flow control valve with non-return non-return should be unscrewed unscrewed as far as possible.

-

The working pressure is switched on with the ball valve. 21

-

Actuate S1, observe the retraction and extension speeds.

-

When frequently frequently changing changing the setting of the flow control control valve with non-return, non-return, make sure to observe both speeds.

Conclusion

The highest possible speed of the piston rod can be achieved by mounting a quickexhaust valve in the corresponding working line of a cylinder.

The pressure release of the cylinder volume then occurs directly via the exhaust exhaust vent port 3 of the th e quick -exhaust -exhaust valve . The quick-exhaust valve is mounted directly at the cylinder

port.

22

Exercise 6 Direct contr ol of a double-acting double-acting cylinder with push-button

Ai m

This exercise provides know-how on the direct control of double-acting cylinders with manually operated 5/2 directional control valves. In addition, the effect of adjustable spring cushioning in double-acting cylinders can be observed. Suggestion for the positi oning of equipment on the workin g plate


List of equipment

Pos. Qty. Description 01 1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve 02 1 Distributor, 6-fold 04 1 Double-acting cylinder with adjustable spring cushioning 08 1 5/2 directional control valve with pushbutton Accessories

23

Task

-

The piston rod of a double-working double-working cylinder (Z1) (Z1) should extend after actuating a button.

-

After releasing releasing the button button (S1), (S1), the piston of the cylinder should should retract retract automatically automatically to its back position.

-


-



-

The cylinder is retracted in neutral position.

-

The double-acting double-acting cylinder is directly directly controlled controlled by a manually manually operated operated 5/2 directional directional control valve (pos. 8).

-

The spring cushioning mounted in the cylinder can be adjusted.

Didactic notes

-

At the end end of the exercise, refer to the 4/2 directional control control valve and explain the difference between the two valve designs.

-

Explain the features features of the various various spool designs (soft-sealing spool, metal metal spool) of 5/2 directional control valves.

-

A watchmaker's screwdriver is necessary for adjusting adjusting the set screw of the spring cushioning.

lnstructions

-


-


-


-

Check and see if the cylinder is retracted in neutral position position and that pressure is applied to it in this position.

-

Actuate S1.

-

Check the proper sequence.

Extra experiment: -

Set the the greatest greatest possible working pressure on the pressure regulator.

-

Both set screws of the spring spring cushioning cushioning are to be unscrewed with a screwdriver as far as possible (counter-clockwise). (counter-clockwise). 24

-

Trigger the cylinder cylinder and and observe observe how hard hard the piston hits hits the end positions. positions.

-

Adjust spring cushioning to a higher higher level level and observe the the effect of of the spring spring cushioning.

Conclusion

The control of a double-acting cylinder occurs principally through a 5/2 5/2 directional control valve as an actuator.

In the basic setting (spring position) of a 5/2 directional control valve supplied with compressed air at port 1, port 2 is always " pressurized" and port 4 always " vented ".

25

Exercise 7 Indirect contro l of a double-acting double-acting cylinder

Ai m

This exercise demonstrates the indirect control of a double-acting cylinder with a pneumatically operated 5/2 directional control valve. Suggestion for the positi oning of equipment an the working plate

Pneumatic Pneumatic circ uit diagram List of equipment

Pos. Qty. Description 01 1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve 02 1 Distributor, 6-fold 04 1 Double-acting cylinder with adjustable spring cushioning 10 1 Pneumatically operated 5/2 directional control valve 06 1 3/2 directional control valve with push-button, closed neutral position Accessories Task

-

The piston rod of a double-acting double-acting cylinder cylinder (drive element Z1), Z1), retracted in neutral position, should extend after actuating a button (controlling element S1). 26

-

Control of the cylinder (Z1) should occur indirectly.

-

After releasing releasing the push-button push-button (S1), the piston of of the cylinder should retract retract automatically to its back position.

-

Additions to the circuit plan.

-



-

A pneumatically pneumatically operated operated 5/2 directional directional control control valve (actuator) is controlled controlled with a manually operated 3/2 directional control valve (signalling element S1).

-

The piston rod of the double-acting cylinder (actuating drive Z1) extends.

Didactic notes

-

Point out how how the control sequence is broken up into different components: signalling elements (signal input) control elements (signal processing) actuators (signal output) drive elements (execution of the movement)

-

Point out out the signal flow direction direction of the signalling signalling elements up to the drive drive element. element.

-

This breakdown breakdown into into components components and the signal flow direction should also also be depicted in the pneumatic circuit diagram.

lnstructions

-

The arrangement arrangement of the equipment equipment an the working plate should be as shown in the arrangement sketch.

-


-

The working pressure is switched an with the ball valve.

-

Check and see if the cylinder cylinder is retracted in neutral neutral position and that pressure is applied to it in this position.

-

Actuate S1.

-

Control the proper sequence.

Conclusion

Air-actuated 5/2 directional control valves are, as all other pneumatically operated directional control valves, controlled with a 3/2 directional control valve as a signalling element. The function of the signalling elements (model of the 3/2 directional control valve) is principally always the closed neutral posit ion (n.c.). (n.c.).

27

Exercise 8 Speed Speed regulation of a double-acting double-acting cylin der

Ai m

In this exercise, the various types of speed regulation (throttling) of the piston rod movements of double-acting cylinders with one-way flow control valves are looked at and the effects are observed. Suggestion for the positi oning of equipment an the working plate


List of equipment

Pos. Qty. Description 04 1 Double-acting cylinder with adjustable spring cushioning 08 1 5/2 directional control valve with push-button 15 2 Flow control valves with non-return, adjustable Air service unit, pressure distributor and accessories (not included in the circuit diagram)

28

Task

-

The extension extension speed and the retraction speed speed of the piston rod of a double-acting double-acting cylinder (drive element Z1), retracted in neutral position, should be infinitely adjustable.

-

The movement movement of the piston rod is not allowed to be a jerky movement, neither neither when extending nor when retracting.

-

lt is assumed that the drive element element (Z1) (Z1) and the actuator (S1) are are mounted at least 2 3 meters apart.

-

The cylinder cylinder is controlled with a manually operated button (actuator S1). After releasing the button (S1), the piston of the cylinder should retract automatically to its back position.

-


-


-

Circuit 1: the speed of the cylinder piston is restricted when extending (restricting the

exhaust) by mounting one flow control valve with wit h non-return in the working line port 2 of the 5/2 directional control valve. -

Circuit 2: the speed of the cylinder piston is restricted when retracting (restricting the

exhaust) by mounting one flow control valve with wit h non-return in the working line port 4 of the 5/2 directional control valve . -

Circuit 3: both speeds of the cylinder piston are restricted (both restricting the exhaust)

by mounting two flow control valves with non-return in both working lines of the 5/2 directional control valve. -

Circuit 4: the speed of the cylinder piston is restricted when extending (air supply

restriction) by mounting one flow control valve with non-return in the working line port 4 of the 5/2 directional control valve. Pneumatic Pneumatic circ uit diagrams

Didactic notes

-

Explain the the difference difference between between the models "hose version" version" and and "screw-in "screw-in version" version" of flow control valves with non-return. non-return.

-

Discuss advantages advantages and disadvantages of speed speed regulation regulation with with flow control valves valves directly mounted in the exhaust ports of the valve. Refer to the differences in the use of this restriction of 4/2 or 5/2 directional control valves in this context.

-

Also refer to the function of flow control valves in silencers or or directly mounted in valves.

29

Instructions

-

The 4 exercises are to be arranged arranged and and piped piped alter each other other an the working working plate.

-

The working pressure is switched an with the ball valve.

-

In all 4 exercises, the adjustment of of the flow control valve with non-return non-return is to be changed. Then observe and judge the movements of the piston and the effect an speed and jerkfree movement.

Conclusion

In the case of double-acting cylinders, the speed regulation in both directions is usually achieved by mounting two flow control valves with non-return in the working lines between cylinder (actuating drive) and 512 directional control valve (actuator). Both flow control valves with non-return are applied as a standard to restrict exhaust air flow .

30

Exercise 9 Controllin g a doubl e-acting e-acting c ylinder, impuls e valve, 2 pushbuttons

Ai m

In this exercise we examine how a pneumatically operated impulse valve functions when controlling a double-acting cylinder. Suggestion for the positi oning of equipment an the work ing plate


List of equipment

Pos. Qty. Description 04 1 Double-acting cylinder with adjustable spring cushioning 11 1 5/2 directional control valve, impulse valve 15 2 Flow control valves with non-return, adjustable 06 1 3/2 directional control valve, with manually operated push-button 07 1 3/2 directional control valve, with manually operated push-button, flow in both directions Air service unit, pressure distributor and accessories (not included in the circuit diagram) 31

Task

-

The piston rod of a double-acting double-acting cylinder cylinder (drive element Z1), Z1), retracted in neutral position, should extend after actuating a button (signalling element S1) and remain extended alter releasing the button (S1).

-

After actuating actuating a second button button (signalling (signalling element element S2), S2), the piston rod rod of the cylinder cylinder should again retract and also remain in this position, even when the button (S2) is no longer actuated.

-

The working speed of of the cylinder cylinder should should be able to be infinitely adjusted in both directions.

-


-



-

By briefly actuating the button S1, the piston rod of the double-acting cylinder extends to its front end position and remains in this position.

-

Only when when the button S2 is also briefly actuated actuated does does the piston rod retract retract back into its initial position. The speed of both cylinder movements can be infinitely adjusted with the flow control valves with non-return.

Didactic notes

-

Discuss basic basic properties properties and cases of application application of pneumatic pneumatic impulse valves.

-

Explain the cause and effect when both control ports ports of the impulse valve receive receive a signal simultaneously.

-

Concerning service and and error error detection detection in the case of pneumatic pneumatic controls it should be pointed out that an impulse valve has no defined basic setting.

Instructions

-

The arrangement arrangement of the equipment equipment on the working plate should be as shown in the arrangement plan.

-


-

The working working pressure pressure is switched on with the ball ball valve. Observe whether the piston of the cylinder remains in the back end position.

-

Actuate S1 briefly briefly and release, the piston of the cylinder cylinder extends.

-

Actuate S2 briefly briefly and release, the piston of the cylinder cylinder retracts.

32

-

When the piston of the cylinder is in the back end position, position, actuate S1 and continue to press. Then additionally actuate button S2 and continue to press. Determine effects.

-

Repeat the same experiment, experiment, but this time with an extended cylinder piston and first continue to press button S2, then actuate button S1.

Conclusion

Impulse valves (e.g. 5/2 directional control impulse valves) store pneumatic signals and are always controlled with 2 pneumatic signals (3/2 directional control valves). An impulse valve remains in the actual switch position until it receives the opposite signal (without the aid of pressurized air). An impulse valve therefore has no defined basic setting (= bistable).

33

Exercise 10 Displacement-de Displacement-dependent pendent contr ol of a double-acting double-acting cylin der, impuls e valve

Ai m

The displacement-dependent control of a double-acting cylinder by using limit switches is demonstrated in this exercise. Suggestion for the positi oning of equipment an the working plate

Example of application

Functional diagram

34

List of equipment

Pneumatic Pneumatic circui t diagrams

Pos. Qty. Description 04 1 Double-acting cylinder with adjustable spring cushioning 11 1 5/2 directional control valve, impulse valve 15 2 Flow control valves with non-return, adjustable 06 1 3/2 directional control valve, with manually operated push-button 13 2 3/2 directional control valves, with roller Air service unit, pressure distributor and accessories (not included in the circuit diagram) Task " SheetSheet-bending bending machine"

-

A double-acting double-acting cylinder is used used in a bending bending machine to form a metal metal sheet.

-

The piston of the cylinder (Z1) (Z1) extends extends when the button (S0) is actuated until until it reaches reaches its front end position and forms the workpiece.

-

Then the piston piston of the cylinder cylinder automatically retracts to its back end position. position.

-

The working speed should be infinitely adjustable in both directions.

-

Additionally: the button (S0) (S0) is normally only actuated actuated briefly. If the button remains remains actuated the cylinder nevertheless must retract to its back end position.

-

Develop the functional diagram with actuator and drive element.

-

Drawing up up the circuit diagram diagram with symbols and port symbols according to ISO 5599 5599 or RP 68 P.


-

If the start button (S0) (S0) is actuated actuated and the feeler roll (S1) mounted in in the back back end position of the cylinder (Z1) is also actuated, then the signal reaches port 14 of the impulse valve and switches it over, extending the piston rod.

-

If limit switch switch S2 is contacted by the piston rod plunger, the signal arrives at at port 12 of the impulse valve, the impulse valve switches back to the right switch position, the piston retracts.

35

-

The limit limit switch S1 is actuated in the back end position position of the piston; piston; now the control control is ready for a new start.

-

The speed of both both cylinder cylinder movements movements is infinitely adjusted with the flow control control valves with non-return.

Didactic notes

-

lt is standard standard to use 3/2 directional control valves in closed, neutral position position with mechanical feeler roll actuation as limit switches for displacement-dependent pneumatic controls.

-

The limit switches are depicted in the lower level of the pneumatic pneumatic circuit circuit diagram like all other signalling and connecting elements and not at their location of actuation!

-

At the location of of actuation only the symbol of the signalling signalling element element with a mark (short line) is entered.

-

In addition, a triangle is drawn at the front front of the piston rod. This represents represents the mechanical actuation by various parts such as cams, plungers, disks, etc.

Instructions

-


-


-


-

When S0 is actuated and the limit switch S1 is mounted properly in the back back end position of the cylinder, the piston rod of the cylinder extends.

Conclusion

Mechanically actuated signalling elements are used as " limit switches " for displacementdependent controls. A limit switch in neutral position can be actuated or not actuated. If a limit switch is actuated in neutral position, then it will be depicted as actuated .

36

Exercise 11 Controllin g a double-acting double-acting cylind er, im pulse valve, 2 reflex nozzles

Ai m

Introducing the pneumatic, proximity switching signalling technology with the example of reflex nozzles and pneumatic amplifiers. Suggestion for the positi oning of equipment an the work ing plate


Functional diagram

37


List of equipment

Pos. Qty. Description 04 1 Double-acting cylinder with adjustable spring cushioning 23 1 Pressure regulating valve with filter and pressure gauge, pe = 0 - 1 bar 11 1 5/2 directional control impulse valve 15 2 Flow control valves with non-return, adjustable 06 1 3/2 directional control valves with pushbutton, closed neutral position 25 2 Reflex nozzles 26 2 3/2 amplifiers Air service unit, pressure distributor and accessories (not included in circuit diagram) 38

Task " Conveying parts from a drop magazine" magazine"

-

After actuating actuating the start button button (S0), (S0), the piston of of a double-acting cylinder pushes parts from a drop magazine on to a conveyer belt.

-

When the piston has pushed the part out of the drop magazine, magazine, it automatically retracts.

-

Additionally: a new start may only be possible possible if the the piston of the cylinder is actually in its back end position.

-

Additionally: mechanically operated signallers cannot be used for scanning scanning cylinder plungers and parts. The signallers must operate "without contact".

-

The working working speed speed of of the cylinder should be infinitely infinitely adjustable adjustable in both directions. directions.

-

Design the functional diagram with actuator and drive element.

-

Drawing up the the circuit diagram with symbols and port port symbols symbols according according to ISO 5599 5599 or RP 68 P.


-

If the start button (S0) (S0) is actuated actuated and the reflex nozzle (B1) mounted in the back end position of the cylinder (Z1) scans the plunger and switches the pneumatic amplifier assigned to it, then the piston rod extends.

-

The piston rod then retracts when the reflex nozzle (B2) mounted in the front front end position of the cylinder switches the assigned pneumatic amplifier and a signal reaches the control port 12 of the impulse valve.

-

The speed speed of both cylinder cylinder movements movements can be infinitely adjusted with the flow control valves with non-return.

Didactic notes

-

Discuss applications applications with proximity proximity switching pneumatic signalling technology in pneumatics such as areas where there is a danger of explosion, situations where there is a danger of dust and contamination.

-

Explain the function of reflex nozzles.

-

Explain the operation principle of pneumatic amplifiers (flapper-nozzle (flapper-nozzle principle).

-

State the proper working pressure of nozzles and amplifiers.

39

Instructions

-


-

Check and see if there is a distance of 2-3 mm set between between the cylinder plunger plunger and the two reflex nozzles.

-


-

Attention: check whether the standard pressure pressure and and the low pressure pressure lines lines on both pressure amplifiers are properly connected.

-

The pressure pressure on the low pressure regulator should be be set at pe = 0.4 bar

-


-

The circuit is to be tested.

Conclusion Reflex nozzles are used in pneumatic controls for proximity switching. These signallers range at approx. 0.3 - 0.5 bar . Therefore work out of physical reasons in the low pr essure range

the output signal X of a reflex nozzle is also a low pressure signal and must be amplified before using in a standard pressure range.

40

Exercise 12 Stop control, double-acting cylinder with 5/3 directional control valve, tensile load

Ai m

This exercise demonstrates the use of a 5/3 directional control valve with closed midposition for stopping a double-acting cylinder. The exercise also shows the effects of leaks in the connecting lines and in the 5/3 directional control valve when holding a load. Suggestion for the positi oning of equipment an the working plate


Functional diagram

41

List of equipment

Pneumatic Pneumatic circu it diagram

Pos. Qty. Description 05 1 Double-acting cylinder, with a device for tensile load 12 1 5/3 directional control valve, closed midposition 15 2 Flow control valves with non-return, adjustable 21 2 Pressure gauges 06 1 3/2 directional control valve, with push button, closed neutral position 07 1 3/2 directional control valve, with push button, flow in both directions (closed neutral position) Air service unit, pressure distributor and accessories (not included in the circuit diagram)

Task " Controlling th e door of a hardening hardening plant"

-

The piston of the double-acting double-acting cylinder cylinder (Z1) opens and closes the doors doors of a hardening plant. The push-button (S1) is to be used to open the door, and the pushbuttons (S2) to dose it again.

-

As soon as one of the push-buttons is no longer actuated, the cylinder stops. The door door then remains in this position.

-

In jog mode, the door can can be brought into any position and and locked (stopped) there.

-

The active pressure is controlled by means of 2 pressure gauges at at the cylinder ports.

-


-

Design the functional diagram with actuator and drive element.

-


42


-

The actuator, actuator, a pneumatically operated 5/3 directional directional control valve valve with closed midposition, is used to control a double-acting cylinder. cylinder.

-

The two signalling elements, S1 and S2 (two 3/2 directional directional control valves, valves, manually manually operated) are used to direct the piston of the cylinder upwards or downwards.

-

As soon as one of the two signalling elements is is actuated, the 5/3 directional control valve moves into the closed c losed mid-position, stopping the cylinder (locked).

-

The weight weight of the the door and with it the special special stopping stopping behavior behavior of the cylinder is replaced by the tensile load.

Didactic notes

-

All tube connections from the actuator to the drive element element must be checked for leaks.

-

Refer to the result result of tubes coming coming loose loose in the working working lines of the cylinder.

-

Point out out the locking of the piston, even when when there there is no working working pressure. pressure.

-

Demonstrate what happens when both signalling elements are actuated.

-

How precise is the stopping with this control?

-

Does the speed regulation have an effect on the precision of the stopping?

-

When observing observing the pressure of the lower cylinder cylinder port, port, pull the piston down lower lower with your hand.

-

Clearly define the difference between stopping (locking) and positioning.

-

Discuss other possible circuits for stop control control (application (application of of non-return non-return valves in the working lines of the cylinder).

-

At the end of the exercise exercise refer to the two other 5/3 directional directional control valves, (5/3 vented mid-position and 5/3 directional control valves, pressurized, mid-position).

lnstructions

-


-

The cylinder must be securely securely mounted mounted with the tensile load (only possible possible with a vertically mounted working plate).

-


-

After turning on the working pressure, the the position of the cylinder, extended extended in neutral position, with the tensile load is not allowed to change.

-

Actuating the signalling element S2 causes the piston rod of the cylinder to move upwards with the weight.

43

-

After releasing releasing the the signalling element S2, the cylinder piston stops but is still "pulled down" a short distance by the weight.

-

At this moment moment (working (working pressure pressure of pe = 5 bar) the pressure pressure in the upper upper cylinder chamber is below p atm, the pressure in the lower cylinder chamber is briefly at approx. 4 bar, but it will surely sink lower.

-

Any leaks in the piping and and in the elements elements cause the pressure pressure to sink lower and at a pressure of about pe = 1 bar at the piston rod side the cylinder piston continues to move downward step by step.

Conclusion 5/3 directional control valves with closed mid-position are used for simple pneumatic

stop control circuits. These valves are mainly pneumatically operated, if there is no control pressure at 14 or 12, then the valve is automatically set in the mid-position by a spring balancing.

44

Exercise 13 13 Pressure-depende Pressure-dependent nt co ntrol of 1 doubl e-acting e-acting cyl inder

Ai m

By using a 3/2 directional control valve with adjustable minimum pressure of response, a pressure-dependent (and in addition displacement-dependent) control of a double-acting cylinder is put into effect. Suggestion for the positi oning of equipment an the working plate


Functional diagram

45

List of equipment

Pneumatic Pneumatic circu it diagram

Pos. Qty. Description 04 1 Double-acting cylinder 11 15 21 06

14 22

1 5/2 impulse valve 2 Flow control valves with non-return, adjustable 1 Pressure gauge 1 3/2 directional control valve, with push button, closed neutral position 2 3/2 directional control valves, with feeler roll 1 3/2 directional control valve, with adjustable operating pressure Air service unit, pressure distributor and accessories (not included in the circuit diagram)

Task " Knuckle-joint Knuckle-joint embossing press"

-

The piston piston of a double-acting cylinder (Z1) (Z1) extends extends and embosses a piece of of metal with the aid of a knuckle-joint embossing die.

-

The piston of the cylinder retracts automatically automatically when when the embossing die has has reached the workpiece and the piece of metal has been embossed with a certain adjustable force (pressure an the cylinder, bottom side).

-

Additionally: a new start should only then be possible possible when the cylinder cylinder is actually in its back end position.

-

The working speed of of the cylinder cylinder should should be able to be infinitely infinitely adjusted in both directions.

-

Design of the functional diagram with actuator actuator and drive element.

-

Drawing up up the circuit diagram diagram with symbols and port symbols symbols according to ISO 5599 or RP 68 P.

46


-

After actuating actuating the signalling element S0 and under under the prerequisite prerequisite that the limit switch S1 has been actuated, a signal reaches the control port 14 of the 5/2 impulse valve. The piston of the cylinder Z1 extends.

-

In its front end position the piston actuates the limit switch S2.

-

When the pressure exceeds the value of of 4.5 bar in the back cylinder chamber chamber of of Z1 and thus in the control line 12 of the pressure-dependent 3/2 directional control valve S5, the signalling element S5 switches.

-

The output output signal of S5 applies pressure pressure to the control control port 12 of the impulse impulse valve.

-

The piston piston of the cylinder cylinder retracts, retracts, actuates S1 in the back end position position and and now the control is ready for a new start.

Didactic notes

-

The adjustable adjustable pressure-dependen pressure-dependentt 3/2 directional directional control control valve is also called a (pressure) delivery valve.

-

The adjustable adjustable pressure-dependent pressure-dependent 3/2 directional directional control control valve valve can also be be mounted mounted in a screw joint, which is directly screwed into the cylinder thread (similar to a flow control valve with non-return).

-

In order to avoid mix-ups, mix-ups, the topic of proportional proportional pressure regulators regulators should be discussed in this context during this exercise.

-

The pressure pressure characterization characterization on the pressure gauge should be be observed observed at different speeds of the piston.

Instructions

-


-


-

The set screw on the pressure-dependen pressure-dependentt 3/2 directional directional control control valve is to be be set counter-clockwise all the way to the left (this should result in an operating pressure of approx. 2 bar).

-

The working pressure is to be turned on.

-

The signalling element S0 is to be actuated.

47

-

The pressure pressure on the pressure pressure gauge gauge should should be observed and adjusted adjusted through through several several attempts with the set screw at the pressure-dependent 3/2 directional control valve so that the piston of the cylinder first retracts when the pressure has reached approx. 4.5 bar.

-

The piston piston of the cylinder cylinder may only retract retract when the limit switch S2 has been actuated.

Conclusion

Pressure-dependent signalling elements in pneumatic controls are 3/2 directional control valves with adjustable response pressure . Pressure-dependent signalling elements (directional control valves) can be recognized by the adjusting arrow in the symbol that is drawn through the middle of the restoring spring.

48

Exercise 14 14 Time-depe Time-dependent ndent cont rol of 1 double-acting double-acting cylind er

Ai m

This exercise provides information on time elements used in pneumatic control technology, their function and application. Suggestion for the positi oning of equipment on the workin g plate


Functional diagram (stroke-time diagram)

49

List of equipment

Pneumatic Pneumatic circui t diagram

Pos. Qty. Description 04 1 Double-acting cylinder 11 15 06

13 9 17

1 5/2 impulse valve 2 Flow control valves with non-return, adjustable 1 3/2 directional control valve, with push button, closed neutral position 2 3/2 directional control valves, with roller 1 3/2 directional control valve, pneumatically operated 1 3/2 directional control time-delay valve, adjustable from 0.15 55 s Air service unit, pressure distributor and accessories (not included in the circuit diagram)

Task " Press-in Press-in and bonding device" device"

-

A loudspeaker loudspeaker membrane membrane and a casing brushed with glue are placed into a heated device by hand.

-

After pressing pressing the start button (S0), the piston of of a double-acting cylinder (Z1) (Z1) extends extends and presses the membrane into the casing for a certain adjustable period of time.

-

After the delay time has elapsed, elapsed, the piston of the cylinder cylinder retracts retracts automatically into its back end position.

-

Note: the time can be set between 2 and 5 seconds and and has to correspond correspond to the period that the parts are actually being pressed together.

-

Additionally: The delay delay time should not be influenced by the continuous actuation of the start button (S0).

-

Additionally: Even Even if the start button (S0) (S0) is continuously actuated, the piston of of the cylinder (Z1) should still only extend once.

-

The working working speed speed of of the cylinder should be infinitely infinitely adjustable adjustable when when extending. extending.

-

Design the functional diagram (stroke-time diagram) with actuator actuator and drive element.

-

Drawing up up the circuit diagram diagram with symbols and port symbols according to ISO 5599 5599 or RP 68 P. 50


-

When the signalling element S0 is actuated, the pneumatic pneumatic signal is sent via the (not yet switched) pneumatically operated 3/2 directional control valve in open neutral position, via the limit switch S1 to the control line 14 of the 5/2 impulse valve.

-

The piston of the cylinder cylinder Z1 extends and and in its front end end position position actuates the limit switch S2.

-

When S2 is actuated, actuated, control air reaches reaches inlet X (Z) of the 3/2 directional directional control delay valve unit.

-

The pressure pressure reaches the control control inlet inlet of the air-actuated air-actuated 3/2 directional directional control control valve valve via the built-in flow control valve and to the volume.

-

The air coming in in through through the flow control valve requires requires some time to fill the volume.

-

If the pressure pressure at the control inlet 12 of the directional control valve in the unit reaches reaches the control pressure of the valve, the 3/2 directional control valve opens. The outlet 2 of the 3/2 directional control delay valve applies pressure to the control line 12 of the 5/2 impulse valve.

-

The piston of the cylinder is delayed in retracting.

-

Additionally: if the button S0 is actuated for for a longer period, the pneumatically pneumatically operated 3/2 directional control valve, pos. 9, switches after a short delay (filling the volume via the flow control valve).

-

The directional directional control control valve interrupts the the signal to S1 and the control inlet inlet 14 of the impulse valve.

-

The control control system can only be started again again if the the button S0 is released released and and then actuated again.

Didactic notes

-

In this exercise the two time functions existing in pneumatic pneumatic control control technology technology are applied.

-

The module module pos. 17 is connected in closed neutral neutral position, position, and the function "time element with operating lag" results. Signal pressure results at port 2 only after the time delay has elapsed.

-

The second second time element is made up of a pneumatically operated 3/2 directional directional control valve pos. 9, a one-way flow control valve and a plastic tube with a length of approx. 500 mm. This directional control valve is connected in open neutral position. This time element is also switched in the function "with operating lag", but in this case the signal at port 2 of the directional control valve is switched off after the time has elapsed.

51

-

The piping piping between the flow control valve with non-return non-return and and the control port port of the 3/2 directional control valve pos. 9 must be absolutely leak-proof.

Instructions

-


-


-

Instead of the volume volume between the one-way one-way flow control valve valve pos. 15 and port 12 of the 3/2 directional control valve pos. 9, a tube of approx. 500 mm length is used.

-

The throttle throttle of the the one-way one-way flow control control valve pos. 15 is to be screwed in nearly nearly all the way.

-

The working pressure is to be switched on.

-

The signalling signalling element element S0 is to be actuated. actuated. Check whether an an impulse of approx. approx. 0.5 s at port 14 of the impulse valve (open tube) is present.

-

The time delay between between actuating the limit switch S2 and the beginning of retraction retraction of the piston should be set at approx. 4 s.

-

The signalling signalling element element S0 should should be actuated for a longer period of of time and and held: the piston of the cylinder extends to the front end position, retracts after the time delay of the time element pos. 17 has elapsed. The piston may not extend again despite the actuated signaller S0.

Conclusion

Time elements in pneumatics are modules and always consist of: 3/2 3/2 directional contr ol valves, flow control valves with non-return and volumes (reservoirs). By adjusting the throttle, the time delay (operating or release lag) is set. The length and precision of the

time delay depends on the volume size and on the response pressure and the type of switching of the directional control valve used.

52

Exercise 15 15 Lo gical contr ol with s huttl e and twin-pressure valves valves

Ai m

This exercise uses a logical control to demonstrate the use of the logic basic functions OR (shuttle valve) or AND (two-pressure valve) in pneumatics. In this exercise, a proximity switching signalling element (reflex nozzle) is also used. Suggestion for the positi oning of equipment an the working plate

List of equipment Pos. 04


Qty. Description 1 Double-acting cylinder

11

1

5/2 impulse valve

15

2

06

1

13

2

08

1

07

1

18 19 24

1 2 1

25 26 20

1 1 1

2 Flow control valves with nonreturn, adjustable 3/2 directional control valve, with push button, closed neutral position 3/2 directional control valves, with roller 5/2 directional control valve, manually operated 3/2 directional control valve, with push button, flow in both directions (closed neutral position) Shuttle valve, OR Twin-pressure valves, AND Pressure control valve with filter and pressure gauge, 0 - 1 bar Reflex nozzle Amplifier, pneumatic Pressure display, pneum. Air service unit, pressure distributor and accessories (not included in the circuit diagram)

53

Single and and multi ple OR OR or AND circui ts wi th shut tle and twin pressure valves


54

Task "Logical control"

-

The piston piston of the double-acting double-acting cylinder (Z1) (Z1) of a supply station supplies supplies workpieces workpieces under the following logical conditions: The start button (S0) or an auxiliary button (S1) is actuated and parts are available in the workpiece magazine (B2).

-

An optical optical display shows whether whether there there are still enough enough parts parts available in the workpiece magazine.

-

The cylinder cylinder should only retract retract into its back end end position if it has has actually reached the the front end position and an acknowledgement button (S4) is actuated.

-

A 5/2 impulse valve is used as an actuator.

-

Additionally: for for scanning work-pieces in the magazine (B2) it is not possible to use a mechanically operated signaller. The scanning should therefore occur in a "non-contact" manner through a reflex nozzle.

-

For economic economic reasons (for example example there are are several several manually manually operated operated 5/2 directional directional control valves) a 5/2 directional control valve is used as a signalling element instead of the auxiliary button (S1).

-


-



-

Signal pressure pressure then reaches the control line 14 of the actuating drive drive (piston extends) if the following conditions prove true: the button S0 OR the button S1 is actuated, AND the reflex nozzle B2 (amplifier pos. 26) has switched.

-

Signal pressure pressure then reaches the the control line 12 (piston retracts) retracts) of the actuating actuating drive if the limit switch S3 AND the button S4 are actuated.

-

The reflex reflex nozzle is supplied with low pressure of 0.4 bar via the pressure pressure regulating regulating valve with filter pos. 24.

-

The pneumatic pneumatic pressure display indicates indicates whether whether the the reflex nozzle or the amplifier is supplying a signal.

55

Didactic notes

-

Demonstrate how the pressure stream of the reflex nozzle can "disturb" any any object at 2 to 3 mm distance (for example a workpiece).

-

The use of 5/2 directional control control valves in the function of a 3/2 directional control valve valve (mounting a blanking plug in port 12) is a frequent occurrence in practice dealing with valve carrier systems. Also if it is best to use as few types of valves as possible out of logistic and service reasons.

-

Introduce the various various AND cases of use of serial connection connection of of signalling elements or twin pressure valves.

-

Compare the AND circuit with an air-operated air-operated 3/2 directional directional control control valve and the technical solution twin pressure valve.

-

To fully cover the topic "Logic "Logic in Pneumatics" you you should also talk about the equivalent circuit for the NOT function (air-operated 3/2 directional control valve, open neutral position).

Instructions

-


-


-

The low pressure regulator is to be adjusted.

-

The working pressure is to be turned on.

-

The logic functions are to be tested.

Conclusion

The shuttle valve is available for the logical OR operation in the pneumatic system control technology. A twin pressure valve is used for the logical AND op erat io n . A "serial connection" of pneumatic signallers also results in an AND function.

56

Exercise 16 Sequential Sequential

contr ol

of

2

double-acting double-acting

cylin ders

witho ut

overlapping signals

Ai m

This exercise helps to understand sequential controls and provides practical knowledge of setting up and commissioning a control system with two pneumatic drives. Practice in developing sequential diagram and pneumatic circuit diagram is exercised. Suggestion for the positi oning of equipment an the working plate

Functional diagram

57

List of equipment


Pos. Qty. Description 04 2 Double-acting cylinders 11 15 06 13

2 5/2 impulse valves 2 Flow control valves with non-return, adjustable 1 3/2 directional control valve, with push button, closed neutral position 4 3/2 directional control valves, with roller Air service unit, pressure distributor and accessories (not included in the circuit diagram)


58

Task "Transport of Workpiece"

-

The workpieces workpieces coming coming in on the right roller roller conveyor conveyor should be elevated elevated and sent in a new direction.

-

After actuating actuating the start button button (S0) the piston of cylinder cylinder 1 (Z1) raises raises the workpieces to the height of the second roller conveyor with its elevating platform.

-

Cylinder 1 (Z1) remains in this position until cylinder 2 (Z2) has pushed pushed the workpieces from the elevating platform onto the upper roller conveyor.

-

When cylinder 2 (Z2) has securely pushed all the workpieces onto the upper roller conveyor, cylinder 1 (Z1) moves down again.

-

Only when cylinder 1 (Z1) has has retracted retracted into its lower end position position does does cylinder 2 (Z2) also retract.

-

Additionally: a new start is only possible when when cylinder cylinder 2 (Z2) is actually in its back end position.

-

The working working speed speed of both cylinders should be infinitely infinitely adjustable adjustable in both directions.

-

The functional functional diagram is to be developed developed with actuator actuator and drive element.

-



-

Two double-acting double-acting cylinders, retracted retracted in neutral neutral position, are displacementdependently controlled by impulse valves.

-

After actuating actuating the start button S0, a control signal signal arrives arrives at port port 14 of the impulse valve for cylinder Z1 via the actuated limit switch S3.

-

The piston piston rod of cylinder Z1 extends extends and in its front front end position actuates actuates the limit switch S2.

-

The limit switch S2 sends sends a signal to the control port 14 of the impulse valve for cylinder 2.

-

The piston rod of cylinder 2 extends into into the front end position and actuates the limit switch S4.

-

The limit switch S4 delivers the control signal signal to port 12 from the impulse valve valve for cylinder Z1.

-

The piston piston of cylinder Z1 retracts and and in its back end position actuates limit limit switch S1.

-

The limit switch S1 delivers a signal to port 12 from from the impulse valve valve for cylinder Z2, Z2, the piston retracts to the back end position.

-

The system control is in its initial position.

59

Didactic notes

-

Again point out that impulse impulse valves valves have have no defined basic position.

-

If system controls do do not operate right away away it is advisable advisable to shut off the limit switches in order to check for errors systematically.

Instructions

-


-


-

All flow control control valves with non-return non-return are are to be set at approx. approx. the mid-restriction mid-restriction of piston rod speed.

-


-

Button S0 should be actuated. Check if the the sequence is correct. correct.

Conclusion

The forced, step by step sequence of a sequential control is realized by an actuating sequence of 3/2 directional control valves with fester rolls as limit switches. If no signals ever simultaneously reach ports 14 and 12 of an actuator, then the control takes additional use of material. place without signal overlapping and without additional

60

Exercise 17 Sequential control of 2 double-acting cylinders with signal overlapping, rollers with idle return

Ai m

This exercise demonstrates a sequential control with two pneumatic drives. The signal overlapping occurring during during this exercise is constructively solved by use of rollers with idle return. Practice is obtained in developing sequential diagrams and pneumatic circuit diagrams. Suggestion for the positi oning of equipment an the working plate

Functional diagram

61

List of equipment


Pos. Qty. Description 04 2 Double-acting cylinders 11 15 06 13 14

2 5/2 impulse valves 2 Flow control valves with non-return, adjustable 1 3/2 directional control valve, with push button, closed neutral position 2 3/2 directional control valves, with rollers 2 3/2 directional control valves, with rollers with idle return Air service unit, pressure distributor and accessories (not included in the circuit diagram)


62

Task " Drilling and and boring jig"

-

The workpiece workpiece that is to be drilled is placed placed into a jig by hand. hand.

-

After actuating actuating the start button button (S0), (S0), the piston of of a double-acting cylinder (Z1) clamps the workpiece.

-

When the workpiece has been clamped, the piston rod rod of the the drilling cylinder (Z2) (Z2) extends, drills the workpiece and retracts (after completing the drilling procedure) automatically back into its end position.

-

When the piston of cylinder 2 (Z2) has has returned returned to its upper end position, position, the piston of cylinder 1 (Z1) also retracts and unclamps the workpiece.

-

Note: If you you detect one or more signal signal overlaps overlaps when developing the circuit diagram, the solution can be found by using rollers with idle return.

-

Additionally: a new start should only only be possible when the cylinder actually actually is in its back end position.

-


-

The functional functional diagram is to be developed developed with actuators actuators and and drive drive elements. elements.

-



-

Both double-acting cylinders are retracted in neutral position.

-

After actuating actuating the start button S0, a control signal signal arrives arrives at port port 14 of the impulse valve for cylinder 1 via the actuated limit switch S1.

-

The piston piston rod of cylinder 1 extends, before reaching the front end position position it actuates valve S2 (with rollers with idle return) briefly, and then continues to extend to the end position. (The valve S2 with rollers with idle return is thus not actuated in the end position!)

-

The short short impulse from signal S2 applies pressure to the control control port port 14 of the impulse valve for cylinder 2.

-

The piston piston rod of cylinder extends to the front front end position and and actuates actuates the limit switch S4.

-

The limit switch S4 transmits the control signal signal from the impulse impulse valve to port 12 for cylinder Z2.

-

The piston piston of cylinder Z2 Z2 retracts and before before reaching reaching the the front end position position it actuates the valve S3 with idle return roller briefly and then continues to extend to the end position. (The valve S3 with idle return roller is thus not actuated in the end position!)

63

-

The short short impulse from signal S3 applies pressure to the control control port port 12 of the impulse valve for cylinder Z1, the piston retracts to its back end position.

-

The control system is in its initial position.

Didactic notes

-

The direction direction of actuation of of the idle return return roller valves is marked by an arrow in the circuit diagram.

-

Point out out the following disadvantages of the solution with idle return roller valves:

-

At high piston rod Speeds the impulses of idle return roller valves are too short. The impulse valves do not switch anymore when long signal lines are used.

-

The moment moment of cylinder movement movement is delayed because because the impulse of the idle return return roller valve does not arrive in the end positions of the cylinder movements. This is especially a problem with short strokes.

Instructions

-


-


-

The idle return roller roller valves should be mounted so that the plunger of the cylinder piston just misses actuating the roller in the end position.

-

When mounting mounting the parts, pay attention to the correct correct direction of actuation actuation of the idle return roller valves.

-


-

The correct sequence is to be checked.

-

Set the maximum piston rod speed with the flow control valves with non-return and again check the correct c orrect sequence.

Conclusion

If signal overlapping occurs through the actuating sequence of the limit switches in a sequential control, it is necessary to use other or additional components (functions) in order to eliminate these signal overlaps. Signallers with idle return rollers are only briefly actuated, send only short impulses in one direction. Idle return rollers are thus used to neutralize signal overlapping instead of standard rollers.

64

Exercise 18 Sequential Sequential contr ol of 2 d ouble-acting ouble-acting cylinders with signal overlapping, c hange-over hange-over valve

Ai m

This exercise demonstrates a sequential control with 2 pneumatic drives, with signal overlapping. A constructive solution with the use of a change-over valve is found. Practical experience in developing sequential diagrams and recognizing signal overlaps is gained, as well as in the methodical development of a pneumatic circuit diagram. Suggestion for the positi oning of equipment an the working plate

List of equipment


Pos. Qty. Description 04 2 Double-acting cylinders 11 15 06 13

3 5/2 impulse valves 2 Flow control valves with non-return, adjustable 1 3/2 directional control valve, with push button, closed neutral position 4 3/2 directional control valves, with rollers Air service unit, pressure distributor and accessories (not included in the circuit diagram)

65

Functional diagram (complete)

66


Task "Press-in device"

-

A bolt is to be pressed pressed in to a work-piece. work-piece. The workpiece is is placed in by hand, hand, the bolt is laid on by hand.

-

After actuating the start button (S0), (S0), the piston of of a double-acting cylinder (Z1) (Z1) pushes pushes the workpiece into a clamping fixture and clamps the workpiece.

-

When the workpiece is clamped, clamped, the piston rod rod of the press-in press-in cylinder cylinder (Z2) (Z2) extends, extends, presses the bolt into the workpiece and automatically retracts to its end position.

-

When the piston of cylinder cylinder 2 (Z2) returns returns to its upper upper end position, the piston of cylinder 1 (Z1) also retracts to its it s end position.

-

The sequence sequence of the control is displacement-dependent. displacement-dependent. Limit switches can be mounted on both cylinders.

-

Additionally: a new start should only be possible if the cylinder cylinder is actually in its back end position.

-

Note: If you you detect one or more signal signal overlaps overlaps when developing the circuit diagram, the solution can be found by using change-over valves. 67

-


-

A complete complete functional functional diagram with signalling signalling elements, controlling element, actuators and drive elements is to be developed.

-



-

Both cylinders are retracted in neutral position.

-

Outlet 2 of the change-over valve, or line 2 is vented.

-

If the start start button S0 supplied supplied by line line 2 is is actuated, a control signal arrives arrives at port port 14 of the change-over valve via the actuated limit switch S1, line 2 is vented and line 1 is pressurized.

-

Pressure is applied directly to the impulse valve at port 14 14 from line 1, the piston piston rod of cylinder 1 extends and in its front end position actuates the limit switch S2.

-

The limit switch S2 supplied supplied by line 1 transmits a signal to control port port 14 of the impulse valve for cylinder 2.

-

The piston rod of cylinder 2 extends to its front end end position position and actuates the limit switch S4.

-

The limit switch S4 supplied supplied by line 1 transmits a control signal signal to port port 12 of the change-over valve, the valve switches the pressurized air from line 1 to line 2.

-

Cylinder 2 of the impulse valve valve directly applies pressure pressure from from line 2 to port port 12, the piston rod of cylinder 2 retracts and in its back end position actuates limit switch S3.

-

The limit switch S3, supplied supplied by line 2, transmits transmits a signal to the control port 12 of the impulse valve for cylinder 1, the piston of cylinder 1 retracts to its back end position.

-

The control system is in its initial position.

-

The proper proper basic position position of the change-over valve valve is reported reported by a pneumatic pressure display.

Didactic notes

-

In this exercise the problems problems concerning concerning an undefined undefined basic basic position of an impulse valve can be demonstrated using the example of the initial position of the change-over valve: If the impulse valve is mounted in the left switch position (pressure on outlet 4, or line 1), then the control system runs automatically in the case of correct piping without actuating the start button.

-

Pay careful attention that that the theoretical order of of 2 supply supply lines is also to be clearly seen in the actual piping. 68

-

Discuss the effect of a continuously continuously activated activated start start button S0 on the control control sequence. sequence.

Instructions

-


-


-

The two supply lines are to be clearly identified through through the special order order of tubes, distributors and pneumatic display (perhaps use a color classification).

-


-

The initial condition of the pneumatic display is to be checked.

-

The proper sequence of the control system is to be checked.

Conclusion

A simple solution to eliminate signal overlapping in sequential control systems is the use of change-over valves . The task of a change-over valve is to switch off the the signals of the

limit switches which are overlapping each other. This solution requires good knowledge of control technology, or of systematic solution methods.

69

EE061 Pneumatic Controls Pr Inst

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