Project Report on Pedal Operated Hack Saw Machine

PROJECT REPORT ON

TITLE OF THE PROJECT Submitted For The Partial fulfillment of Diploma In Mechanical Engineering Submitted by

Ajinkya S. Khedekar : 134110001 Raj V. Patel : 134110007 Prasad C. Ghadashi : 134110018 Vikram H. Mane : 134110076 Year 2015-2016 Under The Guidance of

Prof. K.P.Kudalkar

VEERMATA JIJABAI TECHNOLOGICAL INSTITUTE MATUNGA, MUMBAI-400019 ACKNOWLEDGEMENT Pedal Powered Hacksaw Machine

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“Project” is a very crucial part of every engineering student. To think of something new and different and bringing that imagination into practical is a very tedious job. It was not that easy for us too. But it was due to the kind co-operation & valuable guidance rendered to us by the people we would like to mention; it became easier for us to complete our project successfully. We take the great pleasure to present this project report on “Pedal Powered Hacksaw Machine”. We have taken great care that the information provided by is satisfactorialy enough and correct, but even then we welcome any correction. Written words have an unfortunate tendency to degenerate genuine gratitude into a formality. However, it is the only way to record one’s feelings permanently. Hence we take this opportunity to express our heartfelt thanks to all those who have been associated with our project. First of all, We are thankful to our project guide Prof. K.P.Kudalkar whose constant encouragement, presious guidance and full-fiedge co operation has lead to the success of this project. We would like to thank each other for actively participating and making this project what it is today. It was a full-blooded effort of our whole team without whom our project would have not been fruitful. We would like to thank almighty for making our project a full-fledged success. We would like to express our special thanks to our Department.

CERTIFICATE Pedal Powered Hacksaw Machine

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This is to certify that all the students of this group as mentioned earlier have successfully completed project report on “Pedal Powered Hacksaw Machine”, is found to be satisfactory and approved for the partial fulfillment of Diploma in Mechanical Engg. under the guidance of Prof.K.P.Kudalkar during the academic year 2015-2016 as prescribed by VJTI Mumbai.

INTERNAL EXAMINER

EXTERNAL EXAMINER

Date:Place:-

Pedal Powered Hacksaw Machine

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Contents Chapter

Page No

1

Abstract

5

2

Introduction

6

3

Future scope of the Project

7

4

Subjects Discussed

10

5

Sketch of Pedal Operated Hacksaw Machine

16

6

Main Components of Pedal Operated Hacksaw

17

7

Machine Working Principle

36

8

Advantages and Disadvantages

37

9

Calculations

38

10

References

41


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ABSTRACT :Pedal powered hacksaw machine is a machine which can be used for industrial applications and Household needs in which no specific input energy or power is needed. This project consists of a crank and slider mechanism. In the mechanism pedal is directly connected to the hacksaw through crank and slider mechanism for the processing of cutting the wooden blocks, metal bars, PVC materials. The objective of the modal is using the conventional mechanical process which plays a vital role. The main aim is to reduce the human effort for machining various materials such as wooden blocks, steel, PVC etc. The power hacksaw machine, which runs on human power, works on the principle of the conversion of rotational motion to oscillatory motion. Importance of this project lies in the very fact that it is green project and helps us to reduce our electricity need. Secondly, this cutter can be used and transferred to our working place easily. Moreover, if we want we can generate electricity with our project by connecting it to dynamo, diode and battery.


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INTRODUCTION :Pedal power is the tr.ansfer of energy from a human source through the use of a foot pedal and crank system. This technology is most commonly used for transportation and has been used to propel bicycles for over a hundred years. Less commonly pedal power is used to power agricultural and hand tools and even to generate electricity. Some applications include pedal powered laptops, pedal powered grinders and pedal powered water wells. Some third world development projects currently transform used bicycles into pedal powered tools for sustainable development. This project concentrates on pedal powered hacksaw machining. An individual can generate four times more power (1/4 HP) by pedalling than by hand-cranking. At the rate of ¼ HP, continuous pedalling can be served for only short periods, approximately 10 minutes. However, pedalling at half this power (1/8 HP) can be sustained for close to 60 minutes but power capability can depend upon age. As a consequence of the brainstorming exercise, it was apparent that the primary function of pedal power one specific product was particularly useful: the bicycle. Many devices can be run right away with mechanical energy. A saw is a tool that uses a hard blade or wire with an abrasive edge to cut through softer materials. The cutting edge of a saw is either a serrated blade or an abrasive. A saw may be worked by hand, or powered by steam, water, electric or other power. An abrasive saw uses an abrasive disc or band for cutting, rather than a serrated blade.


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Future Scope of Pedal Powered Hacksaw Machine:-

Rice Threshing


Peanut shelling

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Winnoving

Corn Shelling


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Operating a wood working lathe


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SUBJECTS DISCUSSED :1. Stirling Engine : A stirling engine is a heat engine that operates by cyclic compression and expansion of air or other gas (the working fluid) at different temperatures, such that there is a net conversion of heat energy to mechanical work. More specifically, the Stirling engine is a closedcycle regenerative heat engine with a permanently gaseous working fluid. Closed cycle , in this context, means a thermodynamic in which the working fluid is permanently contained within the system, and regenerative describes the use of a specific type of internal heat exchanger and thermal store, known as the regenerator. The inclusion of a regenerator differentiates the Stirling engine from other closed cycle hot air engines. Originally conceived in 1816 as an industrial prime mover to rival the steam engine, its practical use was largely confined to low-power domestic applications for over a century. The Stirling engine is noted for high efficiency compared to steam engines, quiet operation, and its ability to use almost any heat source. The heat energy source is generated external to the Stirling engine rather than by internal combustion as with the Otto cycle or Diesel cycle engines. Because the Stirling engine is compatible with alternative and renewable energy sources it could become increasingly significant as the price of conventional fuels rises, and also in light of concerns such as peak oil and climate change. This engine is currently exciting interest as the core component of micro combined heat and power (CHP) units, in which it is more efficient and safer than a comparable steam engine. However, it has a low power-to-weight ratio rendering it more suitable for use in static installations where space and weight are not at a premium.


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The energy crisis is increasing day by day, so we have to find more ways to get useful energy. Energy saved is energy produced. Many industries use furnaces for production processes, in which most of the heat is lost. We can use this excess heat to run the sterling engine and hence produce electricity. But as the cost of the project is very high, so we decided to reject it.


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2.Electricity Generation Using Speed Breaker :In this model we show that how we can generate electricity from the busy traffic. Conversion of the mechanical energy into electrical energy is widely used concept. It is a mechanism to generate power by converting the potential energy generated by a vehicle going up on a speed breaker into rotational energy. We can use this simple concept to the project. We can connect one mechanical rod with the dynamo and fit this rod on the surface of the road .When any vehicle moves from this roller then due to friction, vehicle rotate the rod or roller and roller then move the dynamo. When dynamo move, then it generates a voltage and this voltage now connects to the bulbs. In actual practice with the help of this voltage we can charge the battery and then we can use this voltage to light the small bulb. If we install this unit to the any small flyover then with the help of this mechanism, we can generate voltage, and with the help of this voltage we can light the bulb. The second part of the project is the efficient use of energy by using simple electronics. We always see that road lights continuously glow whether vehicles are on the road or not. We can introduce a concept to avoid this wastage of light. We can use two sensors between some distances. When vehicle pass through first sensor it sends the signal to the microcontroller that the vehicle is passing along that particular distance then light will glow for that particular time and when vehicle goes out from the second sensor. Then the second sensor sends a signal to a microcontroller that vehicle has been passed through that particular path then light gets off automatically. Different types of basic electronics components has been used to get the desired output like capacitor, resister etc. Pedal Powered Hacksaw Machine

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We have also used a light diode resistance(LDR) when LDR senses a light around it all the road lights gets off and when LDR senses there is a dark around it then LDR sends a signal to microcontroller then all the road lights gets on. By using a LDR we can avoid a waste of light that glow in a day time. The two sensors are made from the concept of electronics. These sensors are called an infrared sensor which is made from photo diode and light emitting diode each. When any vehicle pass from first sensor then first sensor becomes on, for that time the road lights gets on and when it pass from second sensor the second sensor become on and the first sensor gets off then the road light gets off. It gives low and non-uniform voltage. Also, it is difficult to achieve proper balance between speed and torque, hence we decided against it.


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3.Modification In Local Train’s Compartment :1.For ventilation in local compartments, we use fans which needs

electricity. Sufficient energy loss takes place in ventilation. we can make easy and eco-friendly ventilation system in the compartments using natural air flowing around the compartment due to movement of train. We can attach hollow structures on the roof of compartment as shown in figure which forces the air to come inside and flows through the windows and doors. 2.If we reduce one seat from the row of three seats which is close to

door, it will help people for comfortable boarding and alighting. Since we cannot use this modification in rainy seasons, hence we decided to reject it.


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4. Crop Cutter:India is an agricultural country. The economy of our nation is mostly dependent on agriculture. So for the development of our country, the agricultural sector of our economy should be developed. There are many steps in agriculture field like Ploughing, Sowing, Harvesting etc. Harvesting is the operation of cutting, picking, plucking and digging or a combination of these operations for removing the crop from under the ground or above the ground or removing the useful part or fruits from plants.Harvesting action can be done by four ways:    

Slicing action with a sharp tool. Tearing action with a rough serrated edge High velocity single element impact with sharp edge. Two elements scissors type action.

In India harvesting is done by sickle which is time consuming process. By using crop cutter, it speeds up the harvesting process. Since, trials of this project are not possible in urban cities like Mumbai, hence we decided to reject it.


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5. Pedal Powered Hacksaw Machine :-


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Main Components of Pedal Powered Hacksaw Machine :1. Pedal 2. Sprocket 3. Chain 4. Crank 5. Connecting Rod 6. Flywheel 7. Clutch 8. Bearing Blocks 9. Brake 10. Hacksaw 11. Blade


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1. Pedal :A bicycle pedal is the part of a bicycle that the rider pushes with their foot to propel the bicycle. It provides the connection between the cyclist’s foot or shoe and the crank allowing the leg to turn the bottom bracket spindle and propel the bicycle's wheels. Pedals were initially attached to cranks connecting directly to the driven (usually front) wheel. The safety bicycle, as it is known today, came into being when the pedals were attached to a crank driving a sprocket that transmitted power to the driven wheel by means of a roller chain. Pedals usually consist of a spindle that threads into the end of the crank and a body, on which the foot rests or is attached, that is free to rotate on bearings with respect to the spindle. Pedal will be used to transfer our muscular energy to the large sprocket.


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2. Sprocket:A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain,track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth. Sprockets are used in bicycles, motorcycles, cars, tracked vehicles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Perhaps the most common form of sprocket may be found in the bicycle, in which the pedal shaft carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel . Early automobiles were also largely driven by sprocket and chain mechanism, a practice largely copied from bicycles. Sprockets are of various designs, a maximum of efficiency being claimed for each by its originator. Sprockets typically do not have aflange. Some sprockets used with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to another where slippage is not admissible, sprocket chains being used instead of belts or ropes and sprocket-wheels instead of pulleys. They can be run at high speed and some forms of chain are so constructed as to be noiseless even at high speed. Larger sprocket will take the energy from pedal and transfer it to the smaller sprocket which will further transmit it to the shaft.


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3. Sprocket chain :Sprocket Chain: Roller chain or bush roller chain is the type of chain drive most commonly used for transmission A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission.

Construction of the Chain: There are actually two types of links alternating in the bush roller chain. The first type is inner links, having two inner plates held together by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, consisting of two outer plates held together by pins passing through the bushings of the inner links. The "bushingless" roller chain is similar in operation though not in construction; instead of separate bushings or sleeves holding the inner plates together, the plate has a tube stamped Pedal Powered Hacksaw Machine

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into it protruding from the hole which serves the same purpose. This has the advantage of removing one step in assembly of the chain. The roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the sprocket teeth; however this configuration exhibited extremely rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the wear over a greater area; however the teeth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and provided rolling contact with the teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain as well. There is even very low friction, as long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is of primary importance for efficient operation as well as correct tensioning. Sprocket chain will transfer motion from the large sprocket to the small sprocket.

4. Crank :A crank is a mechanical part able to perform a conversion between reciprocating motion and rotational motion. In a reciprocating engine, it translates reciprocating motion of Pedal Powered Hacksaw Machine

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the piston into rotational motion; whereas in a reciprocating compressor, it converts the rotational motion into reciprocating motion. In order to do the conversion between two motions, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of the connecting rods from each cylinder attach. It is typically connected to a flywheel to reduce the pulsation characteristic of the four-stroke cycle, and sometimes a torsional or vibrational damper at the opposite end, to reduce the torsional vibrations often caused along the length of the crankshaft by the cylinders farthest from the output end acting on the torsional elasticity of the metal. Crank will convert rotary motion of shaft into the reciprocating motion which will further transmit to the hack saw assembly.


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5. Connecting Rod :The connecting rod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion. Connecting rods may also convert rotating motion into reciprocating motion. Historically, before the development of engines, they were first used in this way. As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier mechanisms,


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such as chains, could only pull. In a few two-stroke engines, the connecting rod is only required to push. Today, connecting rods are best known through their use in internal combustion piston engines, such as automotive engines. These are of a distinctly different design from earlier forms of connecting rods, used in steam engines and steam locomotives. We are using the connecting rod to convert the rotary motion of crank into reciprocating motion and supplied it to the hack saw assembly.

6.Flywheel: A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have an inertia called the moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by the application of a torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored


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energy by applying torque to a mechanical load, thereby decreasing the flywheel's rotational speed.

Common uses of a flywheel include: 

Providing continuous energy when the energy source is discontinuous. For example, flywheels are used in reciprocating engines because the energy source, torque from the engine, is intermittent.



Delivering energy at rates beyond the ability of a continuous energy source. This is achieved by collecting energy in the flywheel over time and then releasing the energy quickly, at rates that exceed the abilities of the energy source.



Controlling the orientation of a mechanical system. In such applications, the angular momentum of a flywheel is purposely


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transferred as a torque to the attaching mechanical system when energy is transferred to or from the flywheel, thereby causing the attaching system to rotate into some desired position.

Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a revolution rate of a few thousand RPM. Some modern flywheels are made of carbon fibre materials and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM. Carbon-composite flywheel batteries have recently been manufactured and are proving to be viable in real-world tests on mainstream cars. Additionally, their disposal is more eco-friendly. As our hack saw assembly is inclined, we have to provide more energy to lift up the hack saw assembly. Flywheel will store the energy during downward stroke and supply the stored energy during upward stroke to lift up the hack saw assembly.


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7.Clutch: A clutch is a mechanical device that engages and disengages the power transmission, especially from driving shaft to driven shaft. Clutches are used whenever the transmission of power or motion must be controlled either in amount or over time (e.g., electric screwdrivers limit how much torque is transmitted through use of a clutch; clutches control whether automobiles transmit engine power to the wheels). In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). In these devices, one shaft is typically attached to an engine or other power unit (the driving member) while the other shaft (the driven member) provides output power for work. While typically the motions involved are rotary, linear clutches are also possible. In a torque-controlled drill, for instance, one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two shafts so they may be locked together and spin at the same speed (engaged), locked together but spinning at different speeds (slipping), or unlocked and spinning at different speeds (disengaged). When we will start the machine, we will press the clutch lever so that clutch will get disengaged and prevent the connection of flywheel and crank. As the speed of the flywheel increases, we will release the clutch so that it will get engaged and will connect the flywheel and crank.


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Friction clutches: The vast majority of clutches ultimately rely on frictional forces for their operation. The purpose of friction clutches is to connect a moving member to another that is moving at a different speed or stationary, often to synchronize the speeds, and/or to transmit power. Usually, as little slippage (difference in speeds) as possible between the two members is desired.


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8. Bearing Blocks :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. Many bearings also facilitate the desired motion as much as possible, such as by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts. The term "bearing" is derived from the verb "to bear"; a bearing being a machine element that allows one part to bear (i.e., to support) another. The simplest bearings are bearing surfaces, cut or formed into a part, with varying degrees of control over the form, size, roughness and location of the surface. Other bearings are separate devices installed into a machine or machine part. The most sophisticated bearings for the most demanding applications are very precise devices; their manufacture requires some of the highest standards of current technology. Bearing blocks will be used to provide support to the rotating shaft on which flywheel, crank, clutch, brakes, and sprocket are mounted.


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9. Brake :A brake is a mechanical device that inhibits motion, slowing or stopping a moving object or preventing its motion. Most brakes commonly use friction between two surfaces pressed together to convert the kinetic energy of the moving object into heat, though other methods of energy conversion may be employed. For example, regenerative braking converts much of the energy to electrical energy, which may be stored for later use. Other methods convert kinetic energy into potential energy in such stored forms as pressurized air or pressurized oil. Eddy current brakes use magnetic fields to convert kinetic energy into electric current in the brake disc, fin, or rail, which is converted into heat. Still other braking methods even transform kinetic energy into different forms, for example by transferring the energy to a rotating flywheel. Brakes are generally applied to rotating axles or wheels, but may also take other forms such as the surface of a moving fluid (flaps deployed into water or air). Some vehicles use a combination of braking mechanisms, such as drag racing cars with both wheel brakes and a parachute, or airplanes with both wheel brakes and drag flaps raised into the air during landing. Pedal Powered Hacksaw Machine

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Magnetic brake system: Disclosed is a magnetic brake system for a vehicle, comprising: a plurality of brake disk solenoids for generating the magnetic force; a plurality of brake pad solenoids for generating the magnetic force; a braking sensor for detecting whether a brake pedal is applied; a wheel speed sensor for detecting wheel speed; a magnetic polarity sensor for detecting magnetic polarity of the brake disk solenoids; and a control unit for controlling the brake pad solenoids using signals from the braking sensor, the wheel speed sensor and the magnetic polarity sensor. Sometimes, if we have to stop the machine in case of emergency, then we will press the brake lever so that it will decrease the speed of the hack saw assembly.


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10. 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 Pedal Powered Hacksaw Machine

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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. Panel hacksaws forgo the frame and instead have a sheet metal body; they can cut into a sheet metal panel further than a frame would allow. These saws are no longer commonly available, but hacksaw blade holders enable standard hacksaw blades to be used similarly to a keyhole saw or pad saw. Power tools including nibblers, jigsaws, and angle grinders fitted with metal-cutting blades and discs are now used for longer cuts in sheet metals. On hacksaws, as with most frame saws, the blade can be mounted with the teeth facing toward or away from the handle, resulting in cutting action on either the push or pull stroke. In normal use, cutting vertically downwards with work held in a bench vice, hacksaw blades should be set to be facing forwards. Some frame saws, including Fret Saws and Piercing Saws, have their blades set to be facing the handle because they are used to cut by being pulled down against a horizontal surface.


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11. Blade :Blades are available in standardized lengths, usually 10 or 12 inches for a standard hand hacksaw. "junior" hacksaws are typically 150mm long. Powered hacksaws may use large blades in a range of sizes, or small machines may use the same hand blades. The pitch of the teeth can be anywhere from fourteen to thirty-two teeth per inch (tpi) for a hand blade, with as few as three tpi for a large power hacksaw blade. The blade chosen is based on the thickness of the material being cut, with a minimum of three teeth in the material. As hacksaw teeth are so small, they are set in a "wave" set. As for other saws they are set from side to side to provide Pedal Powered Hacksaw Machine

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a kerf or clearance when sawing, but the set of a hacksaw changes gradually from tooth to tooth in a smooth curve, rather than alternate teeth set left and right. Hacksaw blades are normally quite brittle, so care needs to be taken to prevent brittle fracture of the blade. Early blades were of carbon steel, now termed 'low alloy' blades, and were relatively soft and flexible. They avoided breakage, but also wore out rapidly. Except where cost is a particular concern, this type is now obsolete. 'Low alloy' blades are still the only type available for the Junior hacksaw, which limits the usefulness of this otherwise popular saw. For several decades now, hacksaw blades have used high speed steel for their teeth, giving greatly improved cutting and tooth life. These blades were first available in the 'All-hard' form which cut accurately but were extremely brittle. This limited their practical use to benchwork on a workpiece that was firmly clamped in a vice. A softer form of high speed steel blade was also available, which wore well and resisted breakage, but was less stiff and so less accurate for precise sawing. Since the 1980s, bi-metal blades have been used to give the advantages of both forms, without risk of breakage. A strip of high speed steel along the tooth edge is electron beam welded to a softer spine. As the price of these has dropped to be comparable with the older blades, their use is now almost universal.


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Selection of blade:Proper blade selection is important. Use the three-tooth rule at least three teeth must be in con-tact with the work. Large sections and soft materials require a coarse-tooth blade. Small or thin work and hard materials require a fine-tooth blade. For best cutting action, apply heavy feed pressure on hard materials and large work. Use light feed pressure on soft materials and work with small cross sections. Blades are made in two principal types: flexible-back and all-hard. The choice depends upon use. i) Flexible-back blades -should be used where safety requirements demand a shatterproof blade. These blades should also be used for cutting odd-shaped work if there is a possibility of the work coming loose in the vise. ii) All-hard blade -For a majority of cutting jobs, theall-hard bladeis best for straight, accurate cutting under a variety of conditions. When starting a cut with an all-hard blade, be sure the blade does not drop on the work when cutting starts. If it falls, the blade could shatter and flying pieces cause injuries. Power Hacksaw blade :Blades are also made from tungsten and molybdenum steels, and with tungsten carbide teeth on steel alloy backs. The following “rule-ofthumb” can be followed for selecting the correct blade: Use a 4-tooth blade for cutting large sections or readily machined metals. Pedal Powered Hacksaw Machine

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Use a 6-tooth blade for cutting harder alloys and miscellaneous cutting. Use 10- and 14-tooth blades primarily on light duty machines where work is limited to small sections requiring moderate or light feed pressure.

Mounting a Power Hacksaw blade:The blade must be mounted to cut on the power (back) stroke. The blade must also lie perfectly flat against the mounting plates. If long life and accurate cuts are to be achieved, the blade must be properly tensioned. Many techniques have been developed for properly mounting and tensioning blades. Use a torque wrench and consult the manufacturer’s literature. If the information (proper torque for a given blade on a given machine) is not available, the following methods can be used: Tighten the blade until a low musical ring is heard when the blade is tapped lightly. A high pitched tone indicates that the blade is too tight. A dull thud means the blade is too loose. The shape of the blade pin hole can serve as an indicator of whether the blade is tensioned Pedal Powered Hacksaw Machine

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properly. When proper tension is achieved, the pin holes will become slightly elongated, The blade will become more firmly seated after the first few cuts and will stretch slightly. The blade will require re-tensioning (retightening) before further cutting can be done.

WORKING PRINCIPLE It consists of the pedal arrangement which rotates the crank and through it slider consists of oscillating mechanism. The power is transmitted to the crank and slider mechanism. This mechanism is used to rotate the crank disc; the disc which is having an extended rod is connected to the sliding portion of the hacksaw directly by means of a linkage. The hacksaw is passed through the guide ways by means of maintaining the cutting axis. As the user operated the pedal, the hack saw cuts the various materials automatically with less power. The dead weight is for compressive force while the user operated the foot pedal.


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ADVANTAGES:I. Time saving as compared to simple hacksaw II. Power saving as it is manually operated III. Easy machinery used IV. As it is pedal operated so good for health V. Comfortable then ordinary hacksaw VI. It is portable VII. It could be used wherever metal cutting is done in small scales, including at construction sites and furniture units, or to cut metal for window panes.

DISADVANTAGES:I. It’s totally manually operated II. Time consuming as compared to electrical power hacksaw III. Without human effort it’s not operated IV. Not fit for heavy production


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Calculations:Chain

Driver Sprocket

X

Driven Sprocket Radius of Driver Sprocket = R1 Radius of Driven Sprocket = R2 No. of teeths on Driver Sprocket = T1 No. of teeths on Driven Sprocket = T2 Pitch of the Chain = P Teeth Ratio = T1/T2 Velocity Ratio = (T1/T2 = N2/N1) R1 = P/2 cosec ( 180 / T1 ) R2 = P/2 cosec ( 180 / T2 ) Length of the chain = п (R1 + R2) + 2x + (R1 – R2)2/x


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Input Power = 2 п N T / 60 where, N = Sprocket speed in rpm T = Torque applied by human in Nm T=Fxr where, F = Force applied by human in N r = Length of pedal arm Now, we can increase the torque by increasing the length of pedal from its centre. The cutting force required = п x D x t x τs where D = Diameter of workpiece t = Cutting Depth

τs = Shear strength of material In case of rectangular workpiece, Fmax = 2 x (B+L) x t x τs where, B = Breadth of workpiece L = Length of workpiece Maximum power required = Fmax x V where,

V = velocity of blade

SHEAR STRENGTH OF VARIOUS MATERIALS Pedal Powered Hacksaw Machine

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Metal

τs N/mm2 Carbon steel

0.10% C 0.20% C 0.30% C High strength low alloy steel Silicon Steel Stainless steel Aluminium alloys Copper and Bronze Lead alloys Magnesium alloys Nickel alloys Tin alloys Titanium alloys Zinc alloys


245 to 310 308 to 385 364 to 469 315 to 446 420 to 490 399 to 903 49 to 322 154 to 490 12.8 to 41 119 to 203 245 to 812 20.5 to 77.5 420 to 490 98 to 266

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References: 1. Theory of Machines By R.S. Khurmi and J.K Gupta,1st multicolour edition . 2. ‘A Textbook of Production Engineering ‘ by P.C.Sharma


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Project Report on Pedal Operated Hack Saw Machine

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