3.3.2 Chain strength - MECHSPYNET - MECHANICAL PROJECT



DESIGN AND FABRICATION OF PAPER CUTTING USING GENEVA MECHANISMA Mini project reportSubmitted by E.PARTHASARATHI (512312114061) V.PRASANNA (512312114066) J.SAKTHIVEL (512312114076) M.SUBASH (512312114093)In partial fulfillment for the award of the degreeOfBACHELOR OF ENGINEERINGINMECHANICAL ENGINEERINGS.K.P INSTITUTE OF TECHNOLOGY, TIRUVANNAMALAIANNA UNIVERSITY: CHENNAI 600 025APRIL 2015BONAFIED CERTIFICATE Certified that this project “DESIGN AND FABRICATON OF PAPER CUTTING USING GENEVA MECHANISM” is bona fide work of E.PARTHASARATHI (512312114061) V.PRASANNA (512312114066) J.SAKTHIVEL (512312114076) M.SUBASH (512312114093)Who, carried out this work under my supervision.SIGNATURE SIGNATUREProf. D.LOGANATHAN MR. K.DHAKSHNA MURTHI HEAD OF THE DEPARTMENT ASSISTANT PROFESSORDEPT., MECHANICAL ENGG. DEPT., MECHANICAL ENGG. S.K.P INSTITUE OF TECHNOLOGY S.K.P INSTITUE OF TECHNOLOGYTIRUVANNAMALAI TIRUVANNAMALAI Submitted for university practical examination held on………………….. EXTERNAL EXAMINER INTERNAL EXAMINER ACKNOWLEDGEMENT We would like to express our sincere thanks to, Mr.K.KARUNANITHI, chairmen of SKPIT, and Mr.R.KUPPUSAMY, Secretary of SKPIT, for providing an excellent academic atmosphere in the institution. We would like to thanks DR.K.SENTHIL KUMAR, Principal of SKPIT for his encouragement and advising accomplishing this project work. We would like to express our sincere and heartiest thanks to Prof.D.LOGANATHAN, Head of the department, for his technical support and valuable guidance throughout the course of the project. Without his guidance, our project would not have been more successful. We would like to express our gratitude and thanks to our guide, Mr.K.DHAKSHNA MURTHI, assistant professor, for his technical support and valuable guidance throughout the course of the project, without his guidance our project would not have been more successful. On personal note, we would like to utilize this opportunity to extend our project coordinator Mr.P.NARESHKUMAR, Assistant professor, teaching and supporting staffs of Mechanical Engineering Department, Parents and Friends and to one and all those who helped us complete this project successfully. ABSTRACT The design and fabrication of paper cutting machine using Geneva mechanism is very useful to cut papers in equal and accurate dimensions. Geneva drive is an indexing mechanism that converts the continuous motion into intermittent motion. By means of this mechanism the continuous rotary motion of the sprocket wheel is converted into intermittent rotary motion of roller. Due to the intermittent motion, the paper is moved between the time intervals of cutting periods. Then the paper cutting is achieved by the crank and lever mechanism. The sprocket will act as a crank, then the cutter will act as a lever. These two links are connected by a connecting link. The cutter will be back to its original position by the spring effect. LIST OF CONTENTSCHAPTER NO. TITLE PAGE NO. INTRODUCTION 1 MECHANISMS 2INDEXING MECHANISM 2CRANK AND LEVER MECHANISM 5COMPONENTS AND DESCRIPTION 9GENEVA WHEEL 9SPROCKETS 10ROLLER CHAIN 12PAPER CUTTER 15PAPER ROLLER 17COIL SPRING 18SHAFT 20FRAME AND BASE 22WORKING PRINCIPLE 23DESIGN CALCULATION 25 5.1 DESIGN DOR GENEVA WHEEL 25 5.2 DESIGN FOR GENEVA CAM DRIVE 25 5.3 DESIGN FOR GENEVA CROSS 25 5.4 DESIGN FOR LEVER 27 5.5 DESIGN FOR PAPER FEED 28PART DIAGRAM IN 2D 29 6.1 GENEVA WHEEL 29 6.2 SPROCKET 30 6.3 ROLLER CHAIN 30 6.4 COIL SPRING 31 6.5 SHAFT 31ASSEMBLE DIAGRAM 32COMPONENTS SPECIFICATION 33MATERIAL SELECTION 33NO. OF MATERIAL 34COST ESTIMATION 35PROJECT REVIEW 36ADVANTAGE 36LIMITATIONS 36APPLICATIONS 36 CONCLUSION 37 PHOTOGRAPHY 38 REFERENCES 40 LIST OF FIGURESFIGURE NO. NAME PAGE NO.GENEVA WHEEL (Fig 1) 2GENEVA MECHANISM 3EXTERNAL GENEVA 3INTERNAL GENEVA 4SPHERICAL GENEVA 4FOUR BAR MECHANISM 5CRANK AND LEVER MECHANISM 5GENEVA WHEEL (Fig 2) 9GENEVA WHEEL (Fig 3) 10SPROCKET (Fig 1) 11SPROCKET (Fig 2) 11ROLLER CHAIN (Fig 1) 12ROLLER CHAIN (Fig 2) 13PAPER CUTTER (Fig 1) 15PAPER CUTTER (Fig 2) 16PAPER CUTTER (Fig 3) 16PAPER ROLLER (Fig 1) 17PAPER ROLLER (Fig 2) 18COIL SPRING (Fig 1) 19COIL SPRING (Fig 2) 19SHAFT (Fig 1) 20SHAFT (Fig 2) 21FRAME AND BASE 22DESIGN FOR GENEVA 26PART DIAGRAMS IN 2D 29ASSEMBLED PAPER CUTTING MACHINE 32PHOTOGRAPHY 38 LIST OF TABLESTABLE NO. NAME PAGE NO. MATERIALS USED 33 NO. OF MATERIAL 34 COST ESTIMSTION 35 CHAPTER 1 INTRODUCTION The paper cutting machine is designed, in order to reduce the time for marking and cutting the papers. The dimension of the paper to be cut doesn’t need marking, instead of it Geneva drive is used. Geneva mechanism is commonly used indexing mechanism where an intermittent motion is required. This intermittent motion is useful in moving the paper between the cutting periods. The fabrication of conventional Geneva mechanism is generally simple and inexpensive. Because there is no special curved profile on any of the components except straight lines and circular arcs. The Geneva wheel as designed with four slots. Hence the intermittent motion can be achieved in 360/4 degree of the wheel. The paper cutting is done by the paper cutter by crank and lever mechanism. The sprocket act as a crank. The cutter will act as a lever. This sprocket (crank) is connected to the cutter (lever) by a string (connecting link). The crank has rotary motion which is converted to linear. This linear motion is applied to the paper cutter. Hence, the cutting operation is achieved. After cutting, the spring connected to the cutter will bring the cutter back to its original position. The main purpose of this machine is to reduce time for marking the papers. Hence, this machine is working fully based on timing. CHAPTER 2 MECHANISMS 2.1 INDEXING MECHANISM173736082931000 The Geneva mechanism is used here to get the intermittent motion. This Geneva mechanism is also called as indexing mechanism. Fig. 1 In this mechanism, for every turn of the driver wheel A, the driven wheel B makes a quarter turn. The pin, attached to driver wheel A moves in the slots causing the motion of wheel B. The contact between the lower parts of driver A with the corresponding hollow part of wheel B retains it in position when the pin is out of the slot. Wheel A is cut away near the pin as shown, in order to provide clearance for wheel B as it moves. If one of the slots is closed, A can make less than one revolution in either direction before the pin strikes the closed slot and, stopping the motion.left000Fig. 2 2.1.1 CLASSIFICATION OF GENEVA MECHANISMcenter1080906 1. EXTERNAL GENEVA MECHANISM: In this type of mechanism, the Geneva cross is connected with cam drive externally which is the most popular and which is represented by the device below. Fig. 3 2. INTERNAL GENEVA MECHANISM: In this type of mechanism, the Geneva cross and cam drive are connected internally in the closed box, which is also common and is illustrated by below.center202943 Fig. 41770380100901500 3. SPHERICAL GENEVA MECHANISM: In this type of mechanism the Geneva cross is in spherical shape and cam drive are connected in externally, which is extremely rare and is illustrated in below. Fig. 52.1.2 ADVANTAGES OF GENEVA MECHANISMGeneva mechanism may be the simplest and least Expensive of all intermittent motion mechanisms.They come in a wide variety of sizes, ranging from those used in instruments, to those used in machine tools to index spindle carriers weighing several tons.They have good motion curves characteristics compared to ratchets, but exhibit more “jerk” or instantaneous change in acceleration, than better cam systemsGeneva maintains good control of its load at all Times, since it is provided with locking ring surfaces. 2.2 CRANK AND LEVER MECHANISMThe crank and lever mechanism is a four bar mechanism. A four bar mechanism consists of four rigid link which are linked in the form of quadrilateral by four pin joints. A link that makes complete revolution is called crank, the link opposite to the fixed link is the coupler and forth link is a lever or rocker if oscillates or another crank if rotates. This four bar mechanism has three inversions, namelyDouble crank mechanism.Crank rocker mechanism or crank lever mechanism.Double rocker mechanism. Here the crank rocker or crank lever mechanism is used. In a four bar linkage, if the shorter side link revolves and the other rocks (i.e., oscillates), it is called a crank-rocker mechanism. 44196000 Fig. 61263988182031500 In this case, there is only a slight change, leave the smallest side and connect any of its adjacent side as the frame. Then (in figure) the smallest side ‘s’ will have full 360 degree revolution while the other link adjacent to the frame has only oscillating motion (link p). This kind of mechanism is hence called a crank-lever mechanism or a crank-rocker mechanism or a rotary-oscillating converter. Fig. 7 The crank is a rotating element which is used to transmit the power. The crank and lever mechanism is used to transform rotational motion into translational motion by means of a rotating driving beam, a connection rod and a sliding body. A flexible body is used for the connection rod. The sliding mass is not allowed to rotate. A crank and lever mechanism converts circular motion of the crank into linear motion of the slider. In order for the crank to rotate fully the condition L> R+E must be satisfied where R is the crank length, L is the length of the link connecting crank and slider and E is the offset of slider . The total distance covered by the slider between its two extreme positions is called the path length. Kinematic inversion of crank and lever mechanisms produce ordinary beam engine mechanism. The lever is a movable bar that pivots on a fulcrum attached to a fixed point. The lever operates by applying forces at different distances from the fulcrum, or a pivot. Assuming the lever does not dissipate or store energy, the power into the lever must equal the power out of the lever. As the lever rotates around the fulcrum, points farther from this pivot move faster than points closer to the pivot. Therefore a force applied to a point farther from the pivot must be less than the force located at a point closer in, because power is the product of force and velocity.If a and b are distances from the fulcrum to points A and B and let the force FA applied to A is the input and the force FB applied at B is the output, the ratio of the velocities of points A and B is given by a/b, so we have the ratio of the output force to the input force, or mechanical advantage, is given by . This is the law of the lever, which was proven by Archimedes using geometric reasoning. It shows that if the distance a from the fulcrum to where the input force is applied (point A) is greater than the distance b from fulcrum to where the output force is applied (point B), then the lever amplifies the input force. On the other hand, if the distance a from the fulcrum to the input force is less than the distance b from the fulcrum to the output force, then the lever reduces the input force. The use of velocity in the static analysis of a lever is an application of the principle of virtual work. This equation shows that if the distance a from the fulcrum to the point A where the input force is applied is greater than the distance b from fulcrum to the point B where the output force is applied, then the lever amplifies the input force. If the opposite is true that the distance from the fulcrum to the input point A is less than from the fulcrum to the output point B, then the lever reduces the magnitude of the input force. In our project the paper cutter act as a lever and the sprocket act as a crank. The cutter is connected to the crank by a connecting link (string). The cutter is fixed by a small pin at some distance on one side. The one side of the cutter is connected to the string and a spring. This spring is used to get the cutter back to its original position. When the crank is rotated, the crank pin will be at the top position. Hence the string moves the cutter to get the cutting position. In this time the Geneva will not be engaged. After half cycle of the crank rotation, the pin will be at the bottom position. Hence the spring moves the cutter to its original position. In this time Geneva will be in engaged position. CHAPTER 3 COMPONENTS AND DESCRIPTION3.1 GENEVA WHEEL In our Geneva, the driven wheel has four slots and thus advances by one step of 90 degrees for each rotation of the drive wheel. If the driven wheel has n slots, it advances by 360°/n per full rotation of the drive wheel.982494000 Fig. 8 The drive wheel is connected to the sprocket which rotates by the roller chain. The Geneva wheel is connected to the shaft which has the paper roller. This paper roller is kept to feed the paper. The driver sprocket drives the pin to rotate in the sprocket axis. When pin mesh with the Geneva, it rotates the Geneva wheel by sliding in between the slots given. The Geneva is the driven wheel which moves with an intermittent motion. Hence the power is transmitted to the roller with a given interval of time.center5400 Fig. 9 The diameter of the Geneva wheel is to be same as the diameter of the sprocket wheel. Because there is no need for any speed reduction or increase in speed.3.2 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.103421213659 Fig. 101843405198501000 Sprockets are of various designs, a maximum of efficiency being claimed for each by its originator. Sprockets typically do not have a flange. 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. Fig. 113.3 ROLLER CHAINcenter2066587 Roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. 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. Fig. 12 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 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. 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.center379 Fig. 13 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. 3.3.1 Wear The effect of wear on a roller chain is to increase the pitch (spacing of the links), causing the chain to grow longer. Note that this is due to wear at the pivoting pins and bushes, not from actual stretching of the metal (as does happen to some flexible steel components such as the hand-brake cable of a motor vehicle).The lengthening due to wear of a chain is calculated by the following formula:% = ((M ? (S?P))/ (S?P)) ?100M = the length of a number of links measuredS = the number of links measuredP = Pitch 3.3.2 Chain strength The most common measure of roller chain’s strength is tensile strength. Tensile strength represents how much load a chain can withstand under a one-time load before breaking. Just as important as tensile strength is a chain’s fatigue strength. The critical factors in a chain’s fatigue strength is the quality of steel used to manufacture the chain, the heat treatment of the chain components, the quality of the pitch hole fabrication of the link plates, and the type of shot plus the intensity of shot peen coverage on the link plates. Other factors can include the thickness of the link plates and the design (contour) of the link plates. The rule of thumb for roller chain operating on a continuous drive is for the chain load to not exceed a mere 1/6 or 1/9 of the chain’s tensile strength, depending on the type of master links used (press-fit vs. slip-fit). Roller chains operating on a continuous drive beyond these thresholds can and typically do fail prematurely via link plate fatigue failure.3.4 Paper cutterright2333841 A paper cutter is a tool, designed to cut a large set of paper at once with a straight edge. Paper cutters vary in size. The surface will usually have a grid either painted or inscribed on it, often in half-inch increments, and may have a ruler across the top. At the very least, it must have a flat edge against which the user may line up the paper at right-angles before passing it under the blade. It is usually relatively heavy, so that it will remain steady while in use. On the right-hand edge is a long, curved steel blade, often referred to as a knife, attached to the base at one corner. Fig. 14 Larger versions have a strong compression coil spring as part of the attachment mechanism that pulls the knife against the stationary edge as the knife is drawn down to cut the paper. The other end of the knife unit is a handle. The stationary right edge of the base is also steel, with an exposed, finely-ground edge. When the knife is pulled down to cut paper, the action resembles that of a pair of scissors, only instead of two knives moving against each other, one is stationary. The combination of a blade mounted to a steady base produces clean and straight cuts, the likes of which would have otherwise required a ruler and razor blade to achieve on a single page. Paper cutters are also used for cutting thin sheet metal, cardboard, and plastic. Fig.15 Fig. 16 The blade on a paper cutter is made of steel which makes it almost impossible to break. A variant design uses a wheel-shaped blade mounted on a sliding shuttle attached to a rail. This type of paper cutter is known as a rotary paper cutter. Advantages of this design include being able to make wavy cuts, perforations or just score the paper without cutting, with the use of various circular blades. It is also almost impossible for the user to cut him/herself, except while changing the blade. This makes it safer for home use. Higher-end versions of rotary paper cutters are used for precision paper cutting and are popular for cutting down photographs. An even simpler design uses double-edged blades which do not rotate, but cut like a penknife. While cheaper, this design is not preferable for serious work due to its tendency to tear paper, and poor performance with thick media. 3.5 PAPER ROLLERcenter202843300 Paper roller is an element which is used to roll the paper while the intermittent motion. The paper roller used here is a shaft. A shaft is used to roll the paper. A shaft is a rotating machine element which is used to transmit power from one place to another. There are two types of shaft which are transmission shaft and machine shaft. The machine shaft is an integral part of the machine. Hence machine shaft is used in our project. Fig. 17 center216893000 The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft. In order to transfer the power from one shaft to another, the various members such as pulleys gears etc., are mounted on it. These members along with the forces exerted upon them causes the shaft to bending. In other words, we may say that a shaft is used for the transmission of torque and bending moment. Fig. 183.6 COIL SPRING A coil spring, also known as a helical spring, is a mechanical device, which is typically used to store energy due to resilience and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded. One type of coil spring is a torsion spring: the material of the spring acts in torsion when the spring is compressed or extended. 1750871129500800 The quality of spring is judged from the energy it can absorb. The spring which is capable of absorbing the greatest amount of energy for the given stress is the best one. Metal coil springs are made by winding a wire around a shaped former - a cylinder is used to form cylindrical coil springs. 12380472771775 Fig. 19 Fig. 203.6.1 Types of coil spring are:Tension/extension coil springs, designed to resist stretching. They usually have a hook or eye form at each end for pression coil springs, designed to resist being compressed. A typical use for compression coil springs is in car suspension systems.Torsion springs, designed to resist twisting actions. Often associated to clothes pegs or up-and-over garage doors3.6.2 ApplicationsCoil springs have many applications; notable ones include:Buckling springs in computer keyboardsMattress coils in innerspring mattressesUpholstery coil springs in upholstery3.7 SHAFTcenter132458300 A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft. Fig. 211071677132143500 In order to transfer the power from one shaft to another, the various members such as pulleys gears etc., are mounted on it. These members along with the forces exerted upon them causes the shaft to bending. In other words, we may say that a shaft is used for the transmission of torque and bending moment. Fig. 22 The various members are mounted on the shaft by means of keys or splines. The shafts are usually cylindrical, but may be square or cross shaped in section. They are solid in cross‐section but sometimes hollow shafts are also used. An axle, though similar in shape to the shaft, is a stationary machine element and is used for the transmission of bending moment only. It simply acts as a support for some rotating body such as hoisting drum, a car wheel or a rope sheave. A spindle is a short shaft that imparts motion either to a cutting tool (e.g. drill press spindles) or to a work piece (e.g. lathe spindles) 3.7.1 Types of Shafts 1. Transmission shafts. These shafts transmit power between the source and the machines absorbing power. The counter shafts, line shafts, overhead shafts and all factory shafts are transmission shafts. Since these shafts carry machine parts such as pulleys, gears etc., therefore they are subjected to bending in addition to twisting. 2. Machine shafts. These shafts form an integral part of the machine itself. The crank shaft is an example of machine shaft. The machine shaft is used in our project. The shaft is used to bear the roller, sprockets and the paper roll.3.8 FRAME AND BASEcenter691285 Frames are rigid structures. They maintain their shapes with or without external loads. Fig. 23 Frame and base are called as structures. Which are not used for any power transmission. But frame and base are main elements, because they are the main support for the machine elements. In our project, the base is taken 70 cm in length, 35 cm in width and 2 cm in thickness. The base is made up of mild steel. Hence it is rigid and bears more load on it. It can able to withstand the load produce during the working period. CHAPTER 4 WORKING PRINCIPLE The paper cutting machine is designed to operate manually. Hence a handle is fixed to the crank (sprocket). When the handle is rotated, the crank transmits this power to the second sprocket through the roller chain link. Hence the second sprocket gains rotation. The second sprocket is connected to the pin which is used to engage and disengage the Geneva. The crank is connected to a crank shaft. This crank shaft is tied with a string which act as a connecting link in four bar inversion. The other end of the string is connected to the lever i.e. cutter. This whole setup is arranged in the manner to get accurate process timings. When the cam pin is in extreme right position i.e. engage position, the crank shaft will be at extreme bottom position. Hence the cutter is in full open position and the spring will be in rest position.When the cam pin is in extreme bottom position i.e. disengage position, the crank shaft will be at extreme left position. Hence the cutter is in partial cutting position and the spring will be in partial tension.When the cam pin is in extreme left position i.e. disengage position, the crank shaft will be at extreme top position. Hence the cutter is in full cutting position and spring will be in full tension.When the cam pin is in extreme top position i.e. disengage position, the crank shaft will be at extreme right position. Hence the cutter is in partial cutting position and the spring will be in partial tension.These are the four timing planned in our project to achieve paper cutting while Geneva disengagement and rest position of cutter while Geneva engagement.When the handle is rotated in counter clock wise direction, for the first half rotation. The cam pin engages the Geneva wheel. The cam pin moves from top to bottom and it rotates the roller connected with it. Hence the paper is feed to the cutting area. The length of the paper to be feed will be calculated by the ? of the circumference of the roller. The paper feed can be adjusted by changing the roller diameter. Meanwhile the cutter will be in the open position because the crank shaft will move from right to left through bottom. In second half rotation. The cam pin disengages the Geneva wheel. The cam pin moves from bottom to top and it will not rotate the roller fixed with Geneva. Hence there will be no paper feeding. Meanwhile the cutter will cut the paper because the crank shaft will move from left to right through top. By this action of Geneva and lever in correct timing, the paper is cut in accurate and equal dimensions. We need not to mark the papers before cutting. Thus the intermittent motion is achieved to get the accurate and correct dimensional paper pieces. CHAPTER 5 DESIGN CALCULATION5.1 DESIGN FOR GENEVA WHEEL AND CAM SPECIFICATIONS Number of Slots, Z= 4Radius of Geneva wheel,R = 40 mmDistance between centers of Geneva Wheel &driven wheel, a= 56.5 mmRadius of driving Wheel, rd = 60 mmRadius of cam, r = 40mmRadius of pin, rp =2.5mm 5.2 DESIGN CALCULATION FOR CAM DRIVE Angle of locking section, γ= π/2 (Z+2) =270?Semi-indexing angle(driven) α= π/Z = 45?Semi-indexing angle (driver) β= π(Z-2)/(2Z) =45?Gear ratio ?=1 for Z=4Radius ratio, ?= R/r =1.000Indexing time ratio, ν= β/π =0.2500 5.3 DESIGN CALCULATION FOR GENEVA CROSS FOR GENEVA CROSS:Slot width, t = 5 mmLength of Slot,l= 25 mmShaft diameter, ds= 15 mmThickness, b = 5m Angular velocity of driving crank ω1= 2πN/60 (rad/sec) Angular velocity of driven disc ω2 =λ/ (1-λ) ω (rad/sec) D = r/sin (p/N) The radius of rotation ‘R’ of the Geneva wheel is given by: R = r/tan (p/N) The minimum length of the slot through which the pin on disk W moves should be: S = D-[(D-R) + (D-r)] = R + r - D The Analysis of Geneva wheel is done by drawing the position of the pin and the Geneva wheel at the required position. Fig. 24The position of the Geneva wheel is given by, Differentiating this with respect to time we get, Differentiating again with respect time we get, These equations are valid only in the region – (90-b) to (90-b) of the input crank angle. At all other angles the Geneva wheel is stationary and hence both angular velocity and acceleration are zero. Both the angular and acceleration are plotted as a function of input angle in the accompanying plot for an input angular velocity of 1 rad/sec. 5.4 DESIGN OF LEVERT1 = M1a = M2b = T2Where M1 is the input force to the lever and M2 is the output force. The distances a and b are the perpendicular distances between the forces and the fulcrum.205422551435000The mechanical advantage of the lever is the ratio of output force to input force, This relationship shows that the mechanical advantage can be computed from ratio of the distances from the fulcrum to where the input and output forces are applied to the lever, assuming no losses due to friction, flexibility or wear. 5.5 DESIGN CALCULATION FOR PAPER FEED Length of the paper to be feed can be adjusted by changing the diameter of the roller.The paper feed length = (circumference of the roller)/no. of slots in Geneva wheel L = (2 * π * R) / n Where n is the number of slots in the Geneva wheel. R is the radius of the roller, L is the length of the paper to be feed. CHAPTER 6 PART DIAGRAM IN 2D185420013335000 6.1 Geneva wheel1906270233997500 Fig. 25 Fig. 261517015641985006.2 Sprocket Fig. 27center789156006.3 Roller chain Fig. 28center6808956.4 Coil spring Fig. 29699757681531006.5 Shaft Fig. 30 CHAPETR 7ASSEMBLE PAPER CUTTING MACHINE 107632534226500Fig. 31(a) Fig. 31(b)CHAPTER 8COMPONENTS SPECIFICATION 8.1 MATERIAL SELECTIONS.NO.PARTMATERIAL1Geneva wheelMild steel2SprocketsCast iron3Roller chainStainless steel4Paper cutterSteel5Paper rollerMild steel6Coil springSteel alloy7ShaftMild steel8Frame and baseMild steelTable 1: Material selection8.2 NO. OF MATERIALSS.NOPARTNO. OF1Geneva wheel12Sprockets23Roller chain14Paper cutter15Paper roller16Coil spring27Shaft38Frame and base1Table 2: No. of materials8.3 COST ESTIMATIONS.NOPART AND DESCRIPTIONCOST1Geneva wheel9502Sprockets5503Roller chain1804Paper cutter1505Paper roller1006Coil spring607Shaft3508Frame, base and other materials13509Service charge110010TOTAL4565Table 3: Cost estimationCHAPTER 9PROJECT REVIEW9.1 ADVANTAGENo need for marking the paper.Cutting the paper is easy.It will reduce the time for marking the paper.The dimension of the paper will be accurate.Manufacturing cost is less.No noise pact in size.Can able to cut 5 papers at a time. Can be used for small scale industries. Can able to change the machine elements easily9.2 LIMITATIONSCan’t able to cut the papers above 15 cm width.Can’t able to cut bunch of papers i.e. more than 5 papers.Can’t be used for large scale industries. 9.3 APPLICATIONS 1. It can able to use in paper cutting industries. 2. It can able to use in paper crafting. 3. It can be used in many small scale paper industries. 4. It can be used to cut the color papers for designing.CHAPTER 10 CONCLUSION The design and fabrication of paper cutting machine using the Geneva mechanism is will be very useful in small scale industries. There are many machines based on paper cutting but it has some demerits like large in size, costly, need skilled people to operate and it needs electrical input. But our machine will overcome this demerits by compact in size, less cost, no need for skilled people and there is no need for electrical input. The only need is slight manual input to rotate the handle. The design procedure is done for fabricating the Geneva wheel and other elements of this machine. The paper feed is adjusted by changing the circumference of the roller. Thus the paper cutting in accurate dimensions without marking the paper is achieved by getting the intermittent motion by Geneva mechanism. This intermittent motion is used to feed the paper between the cutting periods of the crank and lever mechanism. The crank and lever mechanism helps in cutting the paper. This mechanism actuates the cutter when the Geneva is in disengaged position. Thus the required intermittent motion is achieved. Hence the paper is feed and cut by crank and lever mechanism. The main aim for the mechanism is to reduce timing for paper cutting and neglect the time for marking the paper, this aim is achieved in our paper cutting machine using Geneva mechanism.center-332740 PHOTOGRAPHY184376829164700 Fig. 32 Fig. 33121920033439100center462700 Fig. 34 Fig. 35 REFERENCE C.Y. Cheng, Y. Lin, Improving dynamic performance of the Geneva mechanism using non-linear spring elements, Mechanism and Machine Theory 30(1995) 119–129.E.A. Dijksman, Jerk-free Geneva wheel driving, Journal of Mechanisms 1 (1966) 235–283.E.A. Fenton, Geneva mechanisms connected in series, ASME Journal of Engineering for Industry 97 (1975) 603–608.E.A. Sadek, J.L. Lloyd, M.R. Smith, A new design of Geneva drive to reduce shock loading, Mechanism and Machine Theory 25 (1990) 589–595.F.L. Litvinov, Gear Geometry and Applied Theory, Prentice-Hall, New Jersey, 1994.Fig. 12. Embodiment of the design and operation sequence.F.L. Litvinov, Theory of Gearing, NASA, Washington, DC, 1989.G. Figliolini, J. Angeles, Synthesis of conjugate Geneva mechanisms with curved slots, Mechanism and Machine Theory 37 (2002) 1043–1061.H.P. Lee, Design of a Geneva mechanism with curved slots using parametric polynomials, Mechanism and Machine Theory 33 (3) (1998) 321–329.J.J. Lee, K.F. Huang, Geometry analysis and optimal design of Geneva mechanisms with curved slots, Journal of Mechanical Engineering Science, Proceedings of the Institution of Mechanical Engineers, Part C 218 (4) (2004) 449–4540–45. I. Artobolevsky, Mechanisms in modern engineering design, Vol. III, MIR Publications Moscow, 1979. Sniegowski J. F., “Chemical Mechanical Polishing: Inhancing the manufacturability of MEMS”. Sniegowski J. F. and Rodgers M. S., “Manufacturing Microsystems-on-a-chip with a 5-Level micromachining technology”. ‘SUMMiT Layer Descriptions’ and ‘SUMMiT V Design Rules, Version 0.8 – 8/17/2000’ , Sandia National Laboratories, Microelectronics Development Laboratory. Sniegowski J. F. and Garcia E. J., “Surface MicroMachined Microengine”, Sensor and Actuators A, vol.48, pp 203-214, 1995 M. Steven Rodgers et al. Al, “Designing and operating electrostatically driven microengines” Sniegowski J. F. and Garcia E. J., “Surface MicroMachined Gear trains Driven by a On-Chip Electrostatic Microengine” Sniegowski J. F. et al, “Monolithic geared-mechanisms driven by a polysilicon surface-micromachined on-chip electrostatic microengine’’, Solid-State Sensor and Actuator Workshop, Hilton Head Is., SC, June 2-6, 1996, pp. 178-182 Maarten P. de Boer et al, “A hinged-pad test structure for sliding friction measurement in micromachining”, SPIE Proceedings, v. 3512, Materials and Device Characterization in Micromachining, Sept. 1998 pp. 241250. ................
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