Bharat main report.docx

8/14/2019 Bharat main report.docx

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PRACTICAL TRAINING PROJECT

KINEMATIC FALL

SUBMITTED TO

AMITY SCHOOL OF ENGINEERING AND TECHNOLOGY

AMITY UNIVERSITY, UTTAR-PRADESH

B.Tech, MAE, SESSION 2012

GUIDED BY: SUBMITTED BY:

Mr. SHUBHAM SHARMA STUDENTSNAME ENROLLMENT NO

ASSISTANT PROFESSOR RAVI PRATAP SINGH A2305410246

DEPARTMENT OF MAE BHARAT SHARMA A2305410244

AUUP SHUBHAM SINGH A2305410243

SHASWAT GUPTA A2305410265

NIKHIL KUMAR A2305410249


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CERTIFICATE

This is to certify that Mr. Ravi Pratap Singh, Mr. Bharat Sharma, Mr. Shubham

Singh, Mr.Shashwat Gupta and Mr. Nikhil Kumar, student of B.Tech in

Mechanical has carried out the work presented in the project of the Practical

Training entitle KINEMATIC FALL APPLICATION OF FOUR BAR

MECHANISMas a part of second year program of Bachelor of Technology inMechanical from Amity School of Engineering and Technology, Amity University,

Noida, Uttar-Pradesh under my supervision.

GUIDED BY:

Mr. SHUBHAM SHARMA

ASSISTANT PROFESSOR

DEPARTMENT OF MAE

AMITY UNIVERSITY

UTTAR-PRADESH


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ACKNOWLEDGEMENT

We feel immense pleasure in submitting a term paper report on KINEMATIC FALL

APPLICATION OF FOUR BAR MECHANICSM. The valuable guidance of our

teaching faculty and our seniors made this study possible. They have been a

constant source of encouragement throughout the completion of this report. We

would like to share our sincere thanks to our guide Mr. Shubham Sharma for his

valuable support and guidance under whom we successfully completed our

practical training project titled KINEMATIC FALL APPLICATION OF FOUR BAR

MECHANICSM. Last but not least we would like to thanks to our institute, ASET,

Amity University, Uttar Pradesh for providing such a platform to expose our

innovative ideas in such a short time. We are also thankful to our parents and

family members for their valuable support.


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TABLE OF CONTENTS

Page no.

1. Introduction 5-11

Degree of freedom Four bar linkage Single slider crank mechanism Application of mechanisms

2. Kinematic fall theory 12

3. Construction 13-16

4. Material used in Construction 17

5. Working 18-21

6. Total cost estimation 22

7. Results and discussions 23-24

9. Conclusions and recommendations 25

9. Implications for future 26

10. References 27


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INTRODUCTION

To start with the discussion we must understand the need of four bar chain

mechanism in the present world. Well, nothing in the present world is movable and

accessible without the application of four bar mechanism. Even the simple gear

train, railways and other locomotives moves and works because by this mechanism.

So, here is the explanation of four bar mechanism.

DEGREES OF FREEDOM

The first criterion that sets the base for the study of fur bar mechanism and its

application is the Concept of degrees of freedom. In the design or analysis of a

mechanism, one of the most important concerns is the number of degrees of

freedom (also termed movability) of the mechanism. It is defined as the number of

inputs parameters that is usually pair variables which must be independently

controlled in order to bring the mechanism into a useful

engineering purpose.

Kutzback Criterion Equation

Consider a plane mechanism with number of links. Since in a mechanism, one of

the links is to be fixed, therefore the number of movable links will be (-1 and thus

the total number of degree of freedom will be 3(n-1) before they are connected to

any other link. In general, the mechanism with number of link connected by j

number of binary joints or lower pairs with degree of freedom being 1 and abreast h

number of higher pairs whose degree of freedom is 2, then the number of degree of

freedom of a mechanism is given

n = 3(-1)-2j-h (1)

This equation is called Kutzback criterion for the movability of a mechanism

having plane motion. If there are no two degree of freedom pairs that is the higher

pairs, then h=0, substituting h=0 in equation 1, we get


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n=3(-1)-2j

FOUR BAR LINKAGE

Also called a four-bar, is the simplest movable closed chainlinkage. It consists of

four bodies, called bars or links, connected in a loop by four joints. Generally, the

joints are configured so the links move in parallel planes, and the assembly is called

a planar four-bar linkage. If the linkage has four hinged joints with axes angled to

intersect in a single point, then the links move on concentric spheres and the

assembly is called a spherical four-bar linkage.

The simplest and the basic kinematic chain is a four bar chain or

quadratic cycle chain, as shown in below fig. It consists of four links p, l, q and s,each of them forms a turning pair. The four links may be of different lengths.

Figure 1

According to Grashoffs lawfor a four bar mechanism, the sum of the shortest and

longest link lengths should not be greater than the sum of the remaining two

link lengths if there is to be continuous relative motion between the two links. A

very important consideration in designing a mechanism is to ensure that the input

crank makes a complete revolution relative to the other links. The mechanism in

which no link makes a complete revolution will not be useful. In a four bar chain,one of the links, in particular the shortest link, will make a complete revolution

relative to the other three links, if it satisfies the Grashoffs law. Such a link is

known as crank or driver.
http://en.wikipedia.org/wiki/Linkage_(mechanical)http://en.wikipedia.org/wiki/Linkage_(mechanical)


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The motion characteristics of a-four-bar mechanism will depend on the ratio of the

link length dimensions. The links that are connected to the fixed link can possibly

have two different types of motion:

i) The link may have a full rotation about the fixed axis (we call this type of

link crank)

The link may oscillate (swing) between two limiting angles (we call this type

of link rocker).

In a four-bar mechanism we can have the following three different types of motion:

i) Both of the links connected to the fixed link can have a full rotation.ii) Both of the links connected to the fixed link can only oscillate. This type of four-

bar is called double-rocker."

iii) One of the links connected to the fixed link oscillates while the other has a full

rotation. This type of four-bar is called crank-rocker.

If l + s > p + q (if the sum of the longest and the shortest link lengths is greater than

the sum of the lengths of the two intermediate links).

Only double-rocker mechanisms are possible (four different mechanisms,

depending on the fixed link).

If l + s = p + q the four possible mechanisms in (1) will result. However these

mechanisms will suffer from a condition known as the change point. The center

lines of all the links are collinear at this position. The follower linkage may change

the direction of rotation. This is an undetermined position. Linkage is a spatial four-

bar linkage with hinged joints that have their axes angled in a particular way that

makes the system movable.

Planar four-bar linkages are importantmechanisms found inmachines.

Thekinematics anddynamics of planar four-bar linkages are important topics

inmechanical engineering.Planar four-bar linkages are constructed from four links

connected in a loop by four onedegree of freedomjoints. A joint may be either are
http://en.wikipedia.org/wiki/Mechanism_(engineering)http://en.wikipedia.org/wiki/Machine_(mechanical)http://en.wikipedia.org/wiki/Kinematicshttp://en.wikipedia.org/wiki/Dynamics_(mechanics)http://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Degrees_of_freedom_(mechanics)http://en.wikipedia.org/wiki/Degrees_of_freedom_(mechanics)http://en.wikipedia.org/wiki/Mechanical_engineeringhttp://en.wikipedia.org/wiki/Dynamics_(mechanics)http://en.wikipedia.org/wiki/Kinematicshttp://en.wikipedia.org/wiki/Machine_(mechanical)http://en.wikipedia.org/wiki/Mechanism_(engineering)


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volute, which is a hinged joint, denoted by R, or a prismatic, as sliding joint,

denoted by P. The planar quadrilateral linkage is formed by four links and four

revolute joints, denoted RRRR. The slider-crank linkage is constructed from four

links connected by three revolute and one prismatic joint, or RRRP. The doubleslider is a PRRP linkage. Planar four-bar linkages can be designed to guide a wide

variety of movements.

Planar quadrilateral linkage

Planar quadrilateral linkage, RRRR or 4R linkages have four rotating joints. One

link of the chain is usually fixed, and is called the ground link, fixed link, or

the frame. The two links connected to the frame are called the grounded links andare generally the input and output links of the system, sometimes called the input

link and output link. The last link is the floating link, which is also called

a coupler or connecting rod because it connects an input to the output.

Assuming the frame is horizontal there are four possibilities for the input and

output links:

A crank: can rotate a full 360 degrees

A rocker: can rotate through a limited range of angles which does not include 0 or

180

A 0-rocker: can rotate through a limited range of angles which includes 0 but not

180

A -rocker: can rotate through a limited range of angles which includes 180 but

not 0

SINGLE SLIDER CRANK MECHANISM

A single slider crank chain is a modification of the basic four bar chain.

It consists of one sliding pair and three turning pair. It is usually, found inreciprocating engine mechanism. This type of mechanism converts rotary motion

into reciprocating motion and vice versa. In single slider crank chain, as shown in

below figure the links 1 and 2, links 2and 3, and links 3 and 4 form three

turning pairs while the links 4 and 1 form a sliding pair.


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Figure 2

The links 1 correspond to the frame of the engine, which is fixed. The link 2

corresponds to the crank; link 3 corresponds to the connecting rod and link 4

corresponds to cross-head. As the crank rotates the cross head reciprocates in the

guides and thus the piston reciprocates in the cylinder. Therefore, using single

slider crank mechanism the work can be easily transmitted to other links to produce

power.

APPLICATION OF MECHANISMS

CraneAn application of path generation is a crane in which an approximate horizontal

trace is needed.

Figure 3

HoodAn example of motion generation is a hood which opens and closes.


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Figure 4

Parallelogram mechanismIn a parallelogram four-bar linkage, the orientation of the coupler does not

change during the motion. The figure illustrates a loader.

Figure 5

Slider-crank mechanismsThe four-bar mechanism has some special configurations created by making

one or more links infinite in length. The slider-crank (or crank and slider)

mechanism shown below is a four-bar linkage with a slider replacing an

infinitely long output link.

Figure 6


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Pull the crank of this mechanism and you will see that it transfers rotary

motion into translation. Most mechanisms are driven by motors, and slider-

cranks are often used to transform rotary motion into linear motion.

Crank and pistonYou can also use the slider as the input link and the crank as the output link.

In this case, the mechanism transfers translational motion into rotary motion.

The pistons and crank in an internal combustion engine are an example of

this type of mechanism.

Figure 7

You might wonder why there is another slider and a link on the left. This

mechanism has twodead points.Block feeder one interesting application of

slider-crank is the block feeder.

Figure 8
http://www.cs.cmu.edu/~rapidproto/mechanisms/chpt5.html#HDR73http://www.cs.cmu.edu/~rapidproto/mechanisms/chpt5.html#HDR73


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KINEMATIC FALL THEORY

Yet another application of four bar linkage is the kinematic fall. This application is

composed of a single crank that drives the other existing links in the structure.While we study the four bar mechanism, it is quite clear to us that every motion has

to be transmitted by the means of a crank that drives the rest of the linkages in the

model, so by using the same technique we have designed this model which is

associated with the cranks that drives the links attached to the one anther which

ultimately moves the carriage situated above the structure.

The working of kinematic fall is similar the crane, parallelogram mechanism and

the hood as mentioned above. Instead it is the amalgamation of all these with the

essence of different working aspect of these. The kinematic fall comprise of fourlinks connected adjacent to each other. The links are made to wok by the means of

a crank. When the crank is rotated by 360 degrees, the links adjacent to it moves to

and fro in an unconstrained motion. The link then drives the other link that is

connected to it but the motion of this link is constrained. With this the carriage

attached to the third link gets its motion which is further supported by another link

for up and down motion. These up and down motion provide it its name the

kinematic fall. The material stored in the carriage could be easily dropped on the

ground and vice-versa.

From above analysis of the model we can also obtain several other purposes. The

very first application of this model could be as a hammer. When the carriage is

replaced by a hammer then with the up and down motion we can easily hit the

obstacle or material situated on the ground. Abreast, the other application is t

uniformly dig the ground as a crane. With a sharp tool on the place of carriage this

model can be transformed into a crane, the other uses include a hood, parallelogram

mechanism.


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CONSTRUCTION

Figure 9

The construction of the project is discussed here. The kinematic fall initially

consisted of the main body that serves as the base of the other assets attached to it.

The main body is made up of a wooden plank with dimensions:

The dimension of the entire body: 405 X 410 X 10 mm. Two wooden planks of dimensions: 405 X 410 mm Two planks of dimension: 10 X 410 mm and One plank f dimension: 10 X 405 mm.One side of the body was left open in order to have access to the interior

connection of the links. The main body was then assembled with the help of

nails. Once the main body was made the construction of the links were

determined. By calculation the positions of the links on the main body was


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determined. Then the next task was to cut the links of desired dimensions. For

this, we required five links of dimensions:

Link 1: 135mm. Link 2: 335mm. Link 3: 150mm. Link 4: 370mm. Link 5: 345mm.

Figure 10 (a)

The motive was to establish the same links on the other side of the body. Once thelinks were cut out of a 5 ft. long wooden strip the next task was to make the

connections on the main body.


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The positions of the links on the main body were made as follows:

Link 1: 345 mm above the base and 45 mm from the left of the body. Link 2: 420 mm above the base and 120 mm from the left of the body. Link 3: 155 mm above the base and 275 mm from the left of the body. Link 4: 260 mm above the base and 340 mm from the left of the body. Link 5: 270 mm above the base and 295 mm from the left of the body.

The angle between the link 3 and link 4 was measured as 24 degrees; this angle was

made for easy movement of the carriage and to avoid any kind of contact of link 4

and link 5.

The links were then joined to the main body with the help of screws. The screws

were then fixed tightly with the nuts. In order to attain the reasonable distance

between each link from the main body, washers were used that served the purpose

of employing different height of all the links from the face of the body. To avoid

any kind of overlap of the links the washers were used.

After the construction of the main body, next step was to make the carriage. The

carriage was made out of wooden plan with the dimensions of the carriage were asfollow:

Two blocks of 15 x 18 cm, Base of 10 x 18 cm, and The sides were 10 x 15 cm.


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Link 4 and link 5 were then connected to the carriage with the help of screws and

they were tightened with nuts in the inner side of the carriage. One side of the

carriage was made inclined so that the material would flow easily. The construction

along with carriage is shown in figure 10(b).

Figure 10 (b)


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MATERIAL USED IN CONSTUCTION

Serial

no

Material Dimensions Quantity

1. Wooden ply 6ft X 4ft 1

2. Wooden strip 5ft long and 1.5 inch thick. 2

3. Nails NA 1 box

4. Screws 16 mm long and diameter5mm.

1 box

5. Nuts Inner threaded of diameter 3

mm.

1 box

6. Washers NA 1 box

7. Paint Black and white 500ml each

8. Wooddust 250 gm. 1

9. Fevicol 500 ml. 1


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WORKING

The working of kinematic fall is discussed below. According to the concept of fourbar mechanism when any one link is provided a rotatory motion (cranks) the

motion is transmitted to the rest of the link that moves in an unconstrained motion.

This motion of the links works according to the Grashoffs law that sates the sum

of the shortest and longest link lengths should not be greater than the sum of

the remaining two link lengths if there is to be continuous relative motion between

the two links.This is a universal law that enables and explains the mechanism

very accurately.

The working of the model without the links has been depicted in the figure 11(a)

and 11(b).

Figure 11(a)

According to the figure 11(a), the main body holds the carriage that rests on the top

of the body. The carriage is held with a support from two links that drives it. When

the material is introduced in the carriage the links drives it to the bottom, this

makes the material to flow out of the carriage and the same process could be easily


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carried on as shown in figure 11(b).

Figure 11(b)

This is the simplest working as designed on solid works; the actual links are not

visible in the figures. While we understand the actual working of the model it isnecessary for us to connect it with the four bar mechanism and more precisely with

single crank mechanism because there is only one crank that drives the rest links in

the structure.

The main working of the kinematic fall starts from its crank that is also its 1 stlink.

The crank which is provided the complete rotation (i.e. 360 degrees) is manually or

by the means of motor is moved as shown in figure 12 (a). When the crank is

initially moved it drives link 2 towards that pushes link 3 and link four forward.

With the forward movement of link 3 and link 4 the link 5 attached to the carriage

tends to move ahead.


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Figure 12(a)

In figure 12(b) it can be seen clearly how with the quarter rotation of crank link 2

completely moves backwards, due to this movement of the link 2, link3 and 4drives and displaces the carriage along with link 5 from the top of the body. Due to

the unconstrained motion of the adjacent links the carriage is successful in moving

ahead. Due to the further motion of crank the carriage ultimately comes on the

ground thus throwing out the material.

Figure 12(b)

Slowly when crank takes exactly half rotation the link 2 is pushed forwards by it.

When the link 1 is pushed forward it automatically forces the carriage to move

upward. This upward motion of the carriage is possible only when link3 and link4

moves up. The entire moment of the link is represent again when crank rotates and

the carriage is able to move up and down. This enables the flow of material in


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specific interval of time and thus the movement of the carriage can also be

automated by the means of a motor.

Figure 12(c)

The working of the model is possible only by the means of roller o turning,

prismatic or sliding and through joints. The model is composed of eight pin joints.

These pin joints supports the links and the carriage structure to the body for easy

flow of work. The option is also distinguished on the basis of the pairs study. There

are 6 turning pairs in the structure. Abreast there are about 3 binary joints in theentire structure. The main purpose of the model is to converts the rotary

motion into reciprocating motion. Thus, this is also the principle of the

kinematic fall.


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TOTAL COST ESTIMATION

Serial no. Material Cost

1. Wooden play Rs.650/-

2. Wooden strips 76 x 2=Rs.152/-

3. Nails Rs.35/-

4. Screws Rs.110/-

5. Nuts Rs.40/-

6. Washers Rs.30/-

7. Paint Rs.300/-

8. Fevicol Rs.150/-

9. Wood dust Rs.30/-

Total cost Rs.1497/-


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RESULTS AND DISCUSSION

Figure 13

The model Kinematic Fall was finally constructed and is shown in figure 13.The

required motion of the links and the carriage was achieved. With the rotation of the

crank the adjacent links moved in an unconstrained motion that transmitted the

power to the other links and thus the carriage was able to move up and down. With

the movement of the carriage the material flowed thorough it easily. The movement

of the entire system was associated with the four-bar mechanism most precisely itcontained of only one crank that transmitted the power to rest of the links in the

system. The main purpose of the model is implemented in the real world also. The

locomotives are also employed with the technique. With the rotation of the crank

the motion is provided to the wheels by the means of a connecting rod in the


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railway. The application of this mechanism is also observed in various fields.

Internal combustion engines, cranes, hoods, block feeders, etc... Employees the four

bar mechanism.

Therefore, the rotary motion is converted into the reciprocating motionis

achieved. Thus, the application of four bar mechanism is established.


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CONCLUSION AND RECOMMENDATIONS

The project was able to meet its aim. The model worked as it was designed for

without any kind of lags. The carriage moved properly up and down. The material

flowed through the carriage easily. Links were properly connected without any kind

of overlaps. The finding from the project was to prove the application of the four

bar mechanism.

There are certain recommendations such as;

1. For the continuous movement of the carriage the crank could be fitted with amotor.

2. To avoid any kind of lags and vibration is the structure the links and jointsmust be lubricated.


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IMPLICATIONS FOR THE FUTURE

This model can be altered to work as a hammer or even as a ground digging

machine. By the means of programming and certain kind of mechanicalattachments it can be used for various other jobs like a multipurpose cutting tool or

even in industries for various other works.


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REFERENCES:

S. Chand & Company Ltd.; R.S Khurmi and J.K Gupta; Theory of Machines;Simple Mechanism; P: 94-118.

McGraw-Hill (1995); Joseph Edward Shigley, john joseph Uicker; theory ofmachines and mechanisms; P: 199-245.

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