DESIGN AND FABRICATION OF PAPER CUTTING USING GENEVA MECHANISM

A Mini project report

Submitted by

E.PARTHASARATHI (512312114061)

V.PRASANNA (512312114066)

J.SAKTHIVEL (512312114076)

M.SUBASH (512312114093)

In partial fulfillment for the award of the degree

Of

BACHELOR OF ENGINEERING

IN

MECHANICAL ENGINEERING

S.K.P INSTITUTE OF TECHNOLOGY, TIRUVANNAMALAI

ANNA UNIVERSITY: CHENNAI 600 025

APRIL 2015

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BONAFIED 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 SIGNATURE

Prof. D.LOGANATHAN MR. K.DHAKSHNA MURTHI HEAD OF THE DEPARTMENT ASSISTANT PROFESSOR

DEPT., MECHANICAL ENGG. DEPT., MECHANICAL ENGG.

S.K.P INSTITUE OF TECHNOLOGY S.K.P INSTITUE OF TECHNOLOGY

TIRUVANNAMALAI TIRUVANNAMALAI

Submitted for university practical examination held on…………………..

EXTERNAL EXAMINER INTERNAL EXAMINER

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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.

ABSTRACTiii

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.

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LIST OF CONTENTS

CHAPTER NO. TITLE PAGE NO.

1 INTRODUCTION 1

2 MECHANISMS 2

2.1 INDEXING MECHANISM 2

2.2 CRANK AND LEVER MECHANISM 5

3 COMPONENTS AND DESCRIPTION 9

3.1 GENEVA WHEEL 9

3.2 SPROCKETS 10

3.3 ROLLER CHAIN 12

3.4 PAPER CUTTER 15

3.5 PAPER ROLLER 17

3.6 COIL SPRING 18

3.7 SHAFT 20

3.8 FRAME AND BASE 22

4 WORKING PRINCIPLE 23

5 DESIGN 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 28

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6 PART 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 31

7 ASSEMBLE DIAGRAM 32

8 COMPONENTS SPECIFICATION 33

8.1 MATERIAL SELECTION 33

8.2 NO. OF MATERIAL 34

8.3 COST ESTIMATION 35

9 PROJECT REVIEW 36

9.1 ADVANTAGE 36

9.2 LIMITATIONS 36

9.3 APPLICATIONS 36

10 CONCLUSION 37

PHOTOGRAPHY 38

REFERENCES 40

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LIST OF FIGURES

FIGURE NO. NAME PAGE

NO.

1. GENEVA WHEEL (Fig 1) 2

2. GENEVA MECHANISM 3

3. EXTERNAL GENEVA 3

4. INTERNAL GENEVA 4

5. SPHERICAL GENEVA 4

6. FOUR BAR MECHANISM 5

7. CRANK AND LEVER MECHANISM 5

8. GENEVA WHEEL (Fig 2) 9

9. GENEVA WHEEL (Fig 3) 10

10. SPROCKET (Fig 1) 11

11. SPROCKET (Fig 2) 11

12. ROLLER CHAIN (Fig 1) 12

13. ROLLER CHAIN (Fig 2) 13

14. PAPER CUTTER (Fig 1) 15

15. PAPER CUTTER (Fig 2) 16

16. PAPER CUTTER (Fig 3) 16

17. PAPER ROLLER (Fig 1) 17

18. PAPER ROLLER (Fig 2) 18

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19. COIL SPRING (Fig 1) 19

20. COIL SPRING (Fig 2) 19

21. SHAFT (Fig 1) 20

22. SHAFT (Fig 2) 21

23. FRAME AND BASE 22

24. DESIGN FOR GENEVA 26

25. PART DIAGRAMS IN 2D 29

26. ASSEMBLED PAPER CUTTING

MACHINE 32

27. PHOTOGRAPHY 38

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LIST OF TABLES

TABLE NO. NAME PAGE NO.

1 MATERIALS USED 33

2 NO. OF MATERIAL 34

3 COST ESTIMSTION 35

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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.

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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 MECHANISM

The Geneva mechanism is used here to get the intermittent motion.

This Geneva mechanism is also called as indexing mechanism.

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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.

Fig. 2

2.1.1 CLASSIFICATION OF GENEVA MECHANISM

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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.

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Fig. 4

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. 5

2.1.2 ADVANTAGES OF GENEVA MECHANISM

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1. Geneva mechanism may be the simplest and least Expensive of all

intermittent motion mechanisms.

2. 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.

3. They have good motion curves characteristics compared to ratchets, but

exhibit more “jerk” or instantaneous change in acceleration, than better

cam systems

4. Geneva 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,

namely

1. Double crank mechanism.

2. Crank rocker mechanism or crank lever mechanism.

3. 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.

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Fig. 6

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

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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

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.

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.

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CHAPTER 3 COMPONENTS AND DESCRIPTION

3.1 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.

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.

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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

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on the axle of the rear wheel. Early automobiles were also largely driven by

sprocket and chain mechanism, a practice largely copied from bicycles.

Fig. 10

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.

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Fig. 11

3.3 ROLLER CHAIN

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

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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.

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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.

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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)) ∗100

M = the length of a number of links measured

S = the number of links measured

P = 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

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drive beyond these thresholds can and typically do fail prematurely via link plate

fatigue failure.

3.4 Paper cutter

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

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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.

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3.5 PAPER ROLLER

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

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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. 18

3.6 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.

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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.

Fig. 19

Fig. 20

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3.6.1 Types of coil spring are:

1 Tension/extension coil springs, designed to resist stretching. They usually

have a hook or eye form at each end for attachment.

2 Compression coil springs, designed to resist being compressed. A typical use

for compression coil springs is in car suspension systems.

3 Torsion springs, designed to resist twisting actions. Often associated to clothes

pegs or up-and-over garage doors

3.6.2 Applications

Coil springs have many applications; notable ones include:

• Buckling springs in computer keyboards

• Mattress coils in innerspring mattresses

• Upholstery coil springs in upholstery

3.7 SHAFT

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.

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Fig. 21

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

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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 BASE

Frames are rigid structures. They maintain their shapes with or without

external loads.

Fig. 23

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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.

1. 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.

2. 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.

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3. 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.

4. 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 ¼ 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.

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CHAPTER 5

DESIGN CALCULATION

5.1 DESIGN FOR GENEVA WHEEL AND CAM

SPECIFICATIONS

1. Number of Slots, Z= 4

2. Radius of Geneva wheel, R = 40 mm

3. Distance between centers of Geneva Wheel &driven wheel, a= 56.5 mm

4. Radius of driving Wheel, rd = 60 mm5. Radius of cam, r = 40mm

6. Radius of pin, rp =2.5mm

5.2 DESIGN CALCULATION FOR CAM DRIVE

1. Angle of locking section, γ= π/2 (Z+2) =270˚2. Semi-indexing angle(driven) α= π/Z = 45˚3. Semi-indexing angle (driver) β= π(Z-2)/(2Z) =45˚

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4. Gear ratio є=1 for Z=45. Radius ratio, µ= R/r =1.0006. Indexing time ratio, ν= β/π =0.2500

5.3 DESIGN CALCULATION FOR GENEVA CROSS FOR GENEVA CROSS:

1. Slot width, t = 5 mm

2. Length of Slot, l= 25 mm

3. Shaft diameter, ds= 15 mm

4. Thickness, 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.

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Fig. 24

The 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 LEVER

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T1 = M1a = M2b = T2

Where 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.

The 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.

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CHAPTER 6

PART DIAGRAM IN 2D

6.1 Geneva wheel

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Fig. 25

Fig. 26

6.2 Sprocket

Fig. 27

6.3 Roller chain

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Fig. 28

6.4 Coil spring

Fig. 29

6.5 Shaft

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Fig. 30

CHAPETR 7

ASSEMBLE PAPER CUTTING MACHINE

Fig. 31(a)

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Fig. 31(b)

CHAPTER 8

COMPONENTS SPECIFICATION 8.1 MATERIAL SELECTION

S.NO. PART MATERIAL

1 Geneva wheel Mild steel

2 Sprockets Cast iron

3 Roller chain Stainless steel

4 Paper cutter Steel

5 Paper roller Mild steel

6 Coil spring Steel alloy

7 Shaft Mild steel

8 Frame and base Mild steel

Table 1: Material selection

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8.2 NO. OF MATERIALS

S.NO PART NO. OF

1 Geneva wheel 1

2 Sprockets 2

3 Roller chain 1

4 Paper cutter 1

5 Paper roller 1

6 Coil spring 2

7 Shaft 3

8 Frame and base 1

Table 2: No. of materials

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8.3 COST ESTIMATION

S.NO PART AND DESCRIPTION COST

1 Geneva wheel 950

2 Sprockets 550

3 Roller chain 180

4 Paper cutter 150

5 Paper roller 100

6 Coil spring 60

7 Shaft 350

8 Frame, base and other materials 1350

9 Service charge 1100

10 TOTAL 4565

Table 3: Cost estimation

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CHAPTER 9

PROJECT REVIEW

9.1 ADVANTAGE

1. No need for marking the paper.

2. Cutting the paper is easy.

3. It will reduce the time for marking the paper.

4. The dimension of the paper will be accurate.

5. Manufacturing cost is less.

6. No noise pollution.

7. Compact in size.

8. Can able to cut 5 papers at a time.

9. Can be used for small scale industries.

10. Can able to change the machine elements easily

9.2 LIMITATIONS

1. Can’t able to cut the papers above 15 cm width.

2. Can’t able to cut bunch of papers i.e. more than 5 papers.

3. Can’t be used for large scale industries.

9.3 APPLICATIONS

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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

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the paper, this aim is achieved in our paper cutting machine using Geneva

mechanism.

PHOTOGRAPHY

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Fig. 32

Fig. 33

l

Fig. 34

Fig. 35

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