PROJECT REPORT 2016
DOUBLE ACTING HACKSAW USING SCOTCH YOKE MECHANISM A PROJECT SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF THE DEGREE OF BACHELOR OF TECHNOLOGY IN MECHANICAL ENGINEERING
From M.M.M.UNIVERSITY OF TECHNOLOGY,GORAKHPUR By Shubham Pandey
1204240049
Devendra Singh
1204231029
Nirbhay Singh
1204240036
Neelesh Kumar
1204240034
Under the Supervision Of Shri DEVESH KUMAR
DEPARTMENT OF MECHANICAL ENGINEERING MADAN MOHAN MALVIYA UNIVERSITY OF TECHNOLOGY Gorakhpur (UP), India
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PROJECT REPORT 2016
CERTIFICATE This is to certify that Mr. Shubham Pandey, Devendra Singh, Neelesh Kumar, Nirbhay Singh, have carried out B.TECH Project and submitted entitled "DOUBLE ACTING HACKSAW USING SCOTCH YOKE MECHANISM " in the partial fulfillment for the award of degree of Bachelor of Technology in Mechanical Engineering from Madan Mohan Malaviya University of Technology, Gorakhpur under my supervision during the academic session 2015-2016. The project embodies result of original work and studies carried out of the students and contents of the project do not form the award of any other degree to the candidate or to anybody else.
Signature of the supervisor
Shri Devesh Kumar
DATED: 9/11/2015
Mechanical Department
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PROJECT REPORT 2016
ACKNOWLEDGEMENT It gives us immense pleasure to present this report of our work on the project entitled as "DOUBLE ACTING HACKSAW USING SCOTCH YOKE MECHANISM". We are highly grateful to our guide Shri Devesh Kumar, Assistant professor, Department of Mechanical Engineering for her keen interest, invaluable guidance and constant encouragement and perpetual support which were instrumental in making this project successful. We are highly obliged to Dr. S.K.Srivastava, Chairman Project and Head of the Department of Mechanical Engineering. He has been constant source of inspiration to us and was extremely patient in solving our numerous problems. Without his help and guidance this project could not have been successful.
DATED: 9/11/2015
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Shubham Pandey
1204240049
Devendra Singh
12042431029
Neelesh Kumar
1204240034
Nirbhay Singh
1204240036
PROJECT REPORT 2016
ABSTRACT Increasing the productivity is one of the main requirements of production engineering in any kind of manufacturing industry. Either by reducing the operation time or by improving the capability of the machine to produce the components in an increased number at the same time is very essential for an industry to achieve the same. This project employs the Scotch yoke mechanism in power hacksaw machine which enables it to cut two components at a time thereby improving the productivity. In today’s world time a machine should be less time consuming. Power hacksaw cut one piece at one time so there was a loss in production rate. Double acting power hacksaw overcome this time consuming problem. Power hacksaw is a fine tooth power saw with blade held under tension in the frame. Double acting power hacksaw cuts two material simultaneously by its scotch yoke mechanism, so the production rate increase twice then that of power hacksaw. Double acting power hacksaw works under by the scotch yoke mechanism. The scotch yoke mechanism convert the rotary motion into the reciprocating motion.
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CONTENTS
PAGE NO.
CHAPTER 1. Introduction about the Project 1.1 Scotch yoke mechanism 1.2 History
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CHAPTER 2. Mechanism 2.1 Principle 2.2 Simple Harmonic Motion 2.3 Mathematical explanation 2.4 Advantage of Simple Harmonic Motion 2.5 Force analysis for scotch yoke mechanism Using the principle of virtual work
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CHAPTER 3. Construction 3.1 Construction 3.2 DC Motor 3.2.1 Principle of DC motor 3.3 Pulley 3.4 Bearing 3.5 Shaft 3.6 Hacksaw 3.7 V-belt
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PROJECT REPORT 2016 CHAPTER 4. Parts Required 4.1 List of Parts using in the machine
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CHAPTER 5. Prototype Building 5.1 Framework 5.2 Scotch yoke Mechanism 5.3 Work table
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CHAPTER 6. Cost Estimation 6.1 Introduction 6.2 What is project cost estimation? 6.3 Purpose of cost estimating 6.4 Cost element 6.5 Type of Cost estimation 6.5.1 Material cost estimation 6.5.2 Machining cost estimation 6.6 Calculation of material cost 6.7 Cost table Estimation 6.8 Total cost estimation
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REFERENCES
LIST OF FIGURES
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PROJECT REPORT 2016 FIG. NO DESCRIPTIO OF FIGURE
PAGE NO
1.
Crank- slider mechanism
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2.
Simple harmonic motion
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3.
Displacement vs Rotation
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4.
Acceleration vs Rotation
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5.
Force analysis
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6.
Double Acting Hacksaw
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7.
Machine component
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8.
Sectional view of DC motor
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9.
Pulley and V-belt
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10.
Scotch yoke mechanism
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INTRODUCTION In this project, we have designed a double acting hacksaw machine. In industries saving the time and saving the manpower is an important thing all over the world.
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PROJECT REPORT 2016 To satisfy the needs of the industries, we have designed a machine. The machine is exclusively intended for the mass production and they represent fast and more effective way to cut the materials. There are numerous types of cutting machines in engineering field, which are useful in fulfilling the requirements. This new machine is used to avoid the energy loss and save time. Scotch yoke mechanism is used for this purpose.
2: SCOTCH YOKE MECHANISMThe Scotch yoke mechanism is a reciprocating motion mechanism, converting the linear motion of a slider into rotational motion, or vice versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part. In many internal combustion engines, linear motion is converted into rotational motion by means of a crankshaft, a piston and a rod that connects them. The Scotch yoke is considered to be a more efficient means of producing the rotational motion as it spends more time at the high point of its rotation than a piston and it has fewer parts.
HISTORYThis linkage was called by Scotsman in 1869 “a crank and a lot headed rod” but now it is known as Scotch yoke mechanism because, in America at least, a scotch was a 8
PROJECT REPORT 2016 slotted bar that was slipped under a collar on a string of well drilling tools to support them while a section was being added. In 1940, Russell Bourke applied this mechanism to internal combustion engine called Bourke 30 Engine.
MECHANISMThis Mechanism is an inversion of Double Slider Crank Mechanism.The inversion is obtained by fixing either the link 1 or link 3.In figure, link 1 is fixed.In this mechanism when the link 2 (which corresponds to crank) rotates about B as centre,the link 4(which corresponds to the frame) reciproctes. The fixed link 1 guides the frame.
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Credit: google images
SIMPLE HARMONIC MOTIONThis mechanism converts the rotary motion into the translatory motion which is simple harmonic in nature.
Mathematical ExplanationSuppose crankshaft is rotating at an angular velocity ‘w’. If ‘r’ is the radius of crank then, Tangential velocity, V=rw
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Credit- Google images
From the mechanism, we have the following relationsComponent of tangential velocity in Y-direction is given by, U=Reciprocating velocity of U-slot. If ‘a’ is the angle made by the tangential velocity with X-axis at any point of time, Component of tangential velocity in Y-direction is U=rw sin (a) U=v sin (a) So, Velocity of U-slot=V sin a
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PROJECT REPORT 2016 As a result, Velocity of U-slot is a function of sine function of a. Now, as we know that a is directly proportional to the time. This implies that the velocity of u-slot is a sine function of a so the motion of U-slot is a simple harmonic motion.
ADVANTAGE OF SHMThe sinusoidal motion, the sinusoidal velocity, the sinusoidal acceleration (assuming constant angular velocity) results in smoother operation of the mechanism.
credit: Google images
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Force Analysis for Scotch Yoke Mechanism using the Principle of Virtual Work
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CONSTRUCTION Machine has the prime mover at the bottom of the machine. The pulley is attached to the body at the top and end of the side portion. Pulley is connected with disc type plate. The pulley and disc has separate connection with one small metal rod through the bearings.
Figure 1. Double acting hacksaw using Scotch Yoke mechanism
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Motor and pulley is connected with one V type belt. The clamp is fixed with the disc and at the end of two shafts. Hack saw connected to the each shaft at the end. Construction of double acting hacksaw using scotch yoke mechanism consist the following components. 1. DC Motor 2. Pulleys 3. Bearings 4. Shaft 5. Hack saw 6. V belt
Figure 2. Front view of double acting hacksaw using scotch yoke mechanism 17
PROJECT REPORT 2016
1. DC motors At the most basic level, electric motors exist to convert electrical energy into mechanical energy. This is done by way of two interacting magnetic fields - one stationary, and another attached to a part that can move. A number of types of electric motors exist, but most BEAM bots use DC motors in some form or another. DC motors have the potential for very high torque capabilities (although this is generally a function of the physical size of the motor), are easy to miniaturize, and can be "throttled" via adjusting their supply voltage. DC motors are also not only the simplest, but the oldest electric motors. The basic principles of electromagnetic induction were discovered in the early 1800's by Oersted, Gauss, and Faraday. By 1820, Hans Christian Oersted and Andre Marie Amperehad discovered that an electric current produces a magnetic field. The next 15 years saw a flurry of cross-Atlantic experimentation and innovation, leading finally to a simple DC rotary motor. A number of men were involved in the work, so proper credit for the first DC motor is really a function of just how broadly you choose to define the word "motor. “A DC motor is a mechanically commutated electric motor powered from direct current (DC). The stator is stationary in space by definition and therefore so is its current. The current in the rotor is switched by the commutator to also be stationary in space. This is how the relative angle between the stator and rotor magnetic flux is maintained near 90 degrees, which generates 18
PROJECT REPORT 2016
the maximum torque. DC motors have a rotating armature winding but non-rotating armature magnetic field and a static field winding or permanent magnet. Different connections of the field and armature winding provide different inherent speed/torque regulation characteristics. The speed of a DC motor can be controlled by changing the voltage applied to the armature or by changing the field current. The introduction of variable resistance in the armature circuit or field circuit allowed speed control. Modern DC motors are often controlled by power electronics systems called DC drives 1.1. Principles of Operation of DC Motor In any electric motor, operation is based on simple electromagnetism. A current-carrying conductor generates a magnetic field; when this is then placed in an external magnetic field, it will experience a force proportional to the current in the conductor, and to the strength of the external magnetic field. As you are well aware of from playing with magnets as a kid, opposite (North and South) polarities attract, while like polarities (North and North, South and South) repel. The internal configuration of a DC motor is designed to harness the magnetic interaction between a current-carrying conductor and an external magnetic field to generate rotational motion. Let's start by looking at a simple 2-pole DC electric motor (here red represents a magnet or winding with a "North" polarization, while green represents a magnet or winding with a "South" polarization).
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Figure: 2 Sectional view of DC Motor
Every DC motor has six basic parts: axle, rotor (a.k.a., armature), stator, commutator, field magnet(s), and brushes. In most common DC motors (and all that Beamers will see), the external magnetic field is produced by high-strength permanent magnets. The stator is the stationary part of the motor, this includes the motor casing, as well as two or more permanent magnet pole pieces. The rotors (together with the axle and attached commutator) rotate with respect to the stator. The rotor consists of windings (generally on a core), the windings being electrically connected to the commutator. The above diagram shows a common motor layout with the rotor inside the stator (field) magnets.
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2. PULLEY A pulley is a basic device or machine made of a wheel with a rim that a cord or rope fits around. The wheel and axle of a pulley make it easier to lift heavy objects with the rope. V belts solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life. They are generally endless, and their general cross-section shape is trapezoidal (hence the name "V"). The "V" shape of the belt tracks in a mating groove in the pulley (or sheave), with the result that the belt cannot slip off. The belt also tends to wedge into the groove as the load increases—the greater the load, the greater solution, needing less width and tension than flat belts.
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3. BEARING A Bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.
4. SHAFT The term shaft usually refers to a rotating element, circular in cross-section, which supports transmission element like gears, pulleys and sprockets and transmits power. The shaft is always stepped with maximum diameter in the middle portion and minimum diameter at two ends, where bearings are mounted.
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5. HACKSAW A hacksaw is a fine-toothed saw, originally and principally for cutting metal. They can also cut various other materials, such as plastic and wood; for example, plumbers and electricians often cut plastic pipe and plastic conduit with them. There are hand saw versions and powered versions (power hacksaws). Most hacksaws are hand saws with a C-shaped frame that holds a blade under tension. Such hacksaws have a handle, usually a pistol grip, with pins for attaching a narrow disposable blade. The frames may also be adjustable to accommodate blades of different sizes. A screw or other mechanism is used to put the thin blade under tension.
6. V BELT V belts (also style V-belts, vee belts, or, less commonly, wedge rope) solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life. They are generally endless, and their general cross-section shape is trapezoidal (hence the name "V"). The "V" shape of the belt tracks in a mating groove in the pulley (or sheave), with the result that the belt cannot slip off.
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PROJECT REPORT 2016
The belt also tends to wedge into the groove as the load increases—the greater the load, the greater the wedging action— improving torque transmission and making the V-belt an effective solution, needing less width and tension than flat belts. . V-belts trump flat belts with their small center distances and high reduction ratios. The preferred center distance is larger than the largest pulley diameter, but less than three times the sum of both pulleys. Optimal speed range is 1,000–7,000 ft/min (300– 2,130 m/min). V-belts need larger pulleys for their thicker crosssection than flat belts.
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CONSTRUCTION OF SCOTCH YOKE MECHANISM The scotch yoke mechanism is constructed with iron bars. Here the crank is made in some length and the yoke is also made using the same material. It is noted that the minimum length of the yoke should be double the length of the crank. The crank and yoke is connected with a pin.
Figure: Scotch yoke mechanism
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Iron bars are welded to both sides of the yoke to get the reciprocating motion. The yoke with the iron bars is fixed on the display board with the help of c clamp. Now the crank is welded to the end of the shaft of the motor. Now the pin on the crank is connected to the yoke. The pin used to connect yoke and crank is a bolt.
PARTS REQUIRED Following parts are needed for construction of the construction of Double acting hacksaw using scotch yoke mechanism. 1. D.C. Motor 2. Aluminum strips with holes 3. Power supply 4. Square tubes 5. Hacksaw 6. Nut-bolts 7. Switches 8. Plywood 9. Slots and guides 10. Pulley and belts 11. Miscellaneous 26
PROJECT REPORT 2016
PROTOTYPE BUILDING:
A sample prototype was constructed with the following specification and governing parameter were calculated.
Known Parameters: 1. Frame Work Length:
68.5 cm
Breadth:
18.5 cm
Height:
71 cm
2. Scotch Yoke Mechanism Tube length:
85.5cm
Tube diameter:
2.5cm
Disc:
14cm
Slider height:
13cm
Slider width:
5cm
Rectangular frame length: 68.5cm Rectangular frame height: 36cm
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PROJECT REPORT 2016 3. Work Table
Table diameter:
7.5cm
Supporting link length:
18cm
Supporting link height:
13cm
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COST ESTIMATION: INTRODUCTION: Cost estimation may be defined as the process of forecasting the expenses that must be incurred to manufacture a product. These expenses take into a consideration all expenditure involved in a design and manufacturing with all related services facilities such as pattern making, tool, making as well as a portion of the general administrative and selling costs.
What is a Project Cost Estimate? A “project cost estimate” is a prediction of the most likely total cost of the identified scope of work for a project. Cost estimates should reflect an overall accuracy indicative of the level of information available at the time the estimate is prepared. Project cost estimates are based on identifying, quantifying and estimating the cost of consuming all the resources (e.g. people, 29
PROJECT REPORT 2016 machines, materials, services, property) required to complete all activities (e.g. planning, engineering, property acquisition, construction, etc.) including appropriate allowances for associated risks and uncertainty (contingency), using prices prevailing at the time the estimate is prepared. Each project is unique. To accurately develop an estimate of costs for a project an estimator must be capable of mentally constructing the project, accounting for all the activities necessary to complete it, and then estimating the costs using prices prevailing at the time the estimate is prepared. Many of the best cost estimators are knowledgeable in both transportation design and construction. PURPOSE OF COST ESTIMATING: The primary purpose of a project cost estimate is to provide a basis for developing, amending, or reviewing a project budget. A cost estimate is a key component of the project business cases, as it is the foremost document to justify/support the funding allocation. Cost estimates are also used in value analysis/value engineering, and program 30
PROJECT REPORT 2016 planning in the Ministry’s capital investment plans. 1. To determine the selling price of a product for a quotation or contract so as to ensure a reasonable profit to the company. 2. Check the quotation supplied by vendors. 3. Determine the most economical process or material to manufacture the product. 4. To determine standards of production performance that may be used to control the cost “...a project manager is only as good as the cost estimate...”
COST ELEMENTS: The Cost Elements are the major categories of work that make up the project. The vast majority of MOTI capital and rehabilitation projects generally entail the same fundamental cost elements regardless of delivery method.
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Cost Elements: 1. Project Management 2. Planning 3. Engineering 4. Environment 5. Property Acquisition 6. Construction (including site supervision) 7. Contingency
TYPES OF COST ESTIMATION:1. Material cost 2. Machining cost MATERIAL COST ESTIMATION: Material cost estimation gives the total amount required to collect the raw material which has to be processed or fabricated to desired size and functioning of the components. 32
PROJECT REPORT 2016 These materials are divided into two categories1. Material for fabrication: In this the material in obtained in raw condition and is manufactured or processed to finished size for proper functioning of the component.
Standard purchased parts: This includes the parts which was readily available in the market like Allen screws etc. A list in orchard by the estimation stating the quality, size and standard parts, the weight of raw material and cost per kg. For the fabricated parts.
MACHINING COST ESTIMATION: This cost estimation is an attempt to forecast the total expenses that may include to manufacture apart from material cost. Cost estimation of manufactured parts can be considered as judgment on and after careful consideration which includes lab our, material and factory services required to produce the required.
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CALCULATION OF MATERIAL COST: The general procedure for calculation of material cost estimation is 1. After designing a project a bill of material is prepared which is divided into two categories. a. Fabricated components b. Standard purchased components 2. The rates of all standard items are taken and added up. 3. Cost of raw material purchased taken and added up. Cost estimation is done as under: Cost of project = (A) material cost + (B) Machining cost + (C) labour cost (A) Material cost is calculated as under:i) Raw material cost ii) Finished product cost i) Raw material cost:It includes the material in the form of the Material supplied by the Steel authority of India limited as the round bars Channels, angles, square rods, plates along with the strip material form. We have to search for the 34
PROJECT REPORT 2016 suitable available material as per the requirement of designed safe values. ii) Finished product cost:Following the components which we have directly purchased from the Market, being easily available and cheaply availably available as compared to their manufacturing cost.
COST TABLE ESTIMATE S.NO 1 2 3 4 5 5 6 7 8 9
COMPONENTS DC Motor Aluminum strips and iron rods Square table (base) Hack-Saw (2) Nut Bolt Switches Plywood Pulley & Disc plate Other stuffs Power supply Block Total
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COST IN RUPEES ₹2000.00 ₹800 ₹500.00 ₹200.00 ₹100.00 ₹50.00 ₹500.00 ₹400.00 ₹300 As per required ₹4850.00
PROJECT REPORT 2016
TOTAL COST ESTIMATION: 1. Labour Cost: Lathe, drilling, welding and power hacksaw cost Labour cost – Rs.800 2. Overhead charges: The overhead charges are arrived by “manufacturing cost” Manufacturing cost = Material cost + Labour cost = Rs.4850 + Rs.800 = Rs.5050 Overhead charges = 20% of the manufacturing cost = Rs.1010 2. Total Cost: Total cost = Material cost + Labour Cost + Overhead charges =Rs.4850 + Rs.800 + Rs.1010 =Rs.6660 Total cost of the project = Rs.6660
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ADVANTAGE:
High torque output with a small cylinder size. Fewer moving parts. Smoother operation Higher percentage of the time spent at top dead centre (dwell) improving theoretical engine efficiency of constant volume combustion cycle though actual gains have not been demonstrated. In an engine application, elimination of joints typically served by a wrist pin, and near elimination of piston skirt and cylinder scuffing, as side loading of piston due to sine of connecting rod angle is eliminated. DISADVANTAGE: Rapid wear of the slot in the yoke caused by sliding friction and high contact pressure. Increased heat loss during combustion due to extended dwell at top dead center offsets any constant volume combustion improvements in real engines. APPLICATION: This setup is most commonly used in control valve actuators in high pressure oil and gas pipelines. It has been used in various internal combustion engines, such as the Bourke engine, Sytech engine and many hot air engines and steam engines. It is also used in multipurpose machine and I.C. engines.
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References
"The SyTech Scotch Yoke Engine". Auto Speed. Retrieved 2008-07-08.
https://en.wikipedia.org/wiki/Scotch_yoke http://link.springer.com/article https://www.scribd.com/Scotch-Yoke-Mechanism http://gogogadgetscott.info/engineering/alfredstate/EMET3424/Lab7_SCOT CH_YOKE_MEASUREMENTS.pdf http://www.mechengg.net/2015/08/double-acting-hack-saw-machineoperated.html https://www.youtube.com/watch?v=hsaoTo1vuY4 https://www.scribd.com/doc/91644590/Project-Report http://topicideas.org/ppt/scotch-yoke-mechanism-report-in-mini-project-inpdf https://www.nmri.go.jp/eng/khirata/stirling/scotch/scotch00_e.html Theory of Machines and Mechanisms-Ghosh & Mallik Theory of Machines – Khurmi & Gupta Theory of Machines-S.S. Rattan
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