CHAPTER
– 1 INTRODUCTION
1.1
AN IDEA ABOUT THE PROJECT
An idea involves thinking thinking is the best best exercise for clearing the concepts. Thinking is just like a simulator where different ideas, through & actions are compiled to get results. Thinking needs experience to to testing result experience comes by evaluating evaluating our thinking by a perfect mocker and eliminating flows from it 80 thinking is the first step to projection. By this project we get a chance to think and testing our book and knowledge. The idea of can crusher is not only to crush a can into a small piece cut also to exercise that how an engineering subject can be utilized to get an output or a product which can ease the human workings. 1.2
PURPOSE OF THE PROJECT
Basically the project can crusher is designed to crush waste can into small pieces so that they can easily stored and transfer from on e place to other. Since cans are best way to preserve food therefore there use in preservation of food is in creating day by day. The other fact is that these cans can be recycled easily and does not affect the environment like politeness. But at the time of waste handling and its transportation these cans must occupy minimum space or possible so as to store and transport them in large quantity and here comes o ur can crusher. The other sort purpose of our project is to testing our knowledge and reusing our subjects before entering the real world. Because of the end to our degree we need to learn how engineering give shape to structure and machines. So the purpose of the project is to justify the engineering facts and the purpose pu rpose of this report is to write our opinions about these engineering facts.
1
1.3
SUBJECTS COVERED UNDR THE PROJECT
The Project "Can Crusher" is not a single single book project. It links the several discipline discipline and mechanical engineering and general physics several derivations and formulates from different subjects are mention in next chapters. chapters. Some of the subjects need to be studied before starting the projects are. 1.
Kinematics of machines (KOM):
This subject tells us now how the motion is embedded in a machine. This subject leads to know how different links and pairs come together to form mechanize and from this subject we get the brain of our project i.e. single slider crank chain mechanism.
2.
Machine Design:
Since our project has gears involved to get two different machinery speeds so we should also be familiar with gear designing. 3.
Strength of Materials:
Stress analysis is as always necessary for any mechanical project so we also near to analysis. Our parts such as rotating disk, Piston, handle gears and keep them away from stress can. 4.
Mathematics:
Mathematics is heart of engineering every single element of our project have definite dominations which are calculated from derived formulas. 1.4
PRODUCTION AND MARKET EXPERIENCE
Production provides knowledge about welding, cutting and machining during production we also got knowledge about interesting facts that production requires knowledge of market experience Market knowledge reduces the expense of manufacture. We did a lot of mistakes mistakes while designing the the project. One of the biggest mistakes is is designing the project without standardized raw material.
2
1.3
SUBJECTS COVERED UNDR THE PROJECT
The Project "Can Crusher" is not a single single book project. It links the several discipline discipline and mechanical engineering and general physics several derivations and formulates from different subjects are mention in next chapters. chapters. Some of the subjects need to be studied before starting the projects are. 1.
Kinematics of machines (KOM):
This subject tells us now how the motion is embedded in a machine. This subject leads to know how different links and pairs come together to form mechanize and from this subject we get the brain of our project i.e. single slider crank chain mechanism.
2.
Machine Design:
Since our project has gears involved to get two different machinery speeds so we should also be familiar with gear designing. 3.
Strength of Materials:
Stress analysis is as always necessary for any mechanical project so we also near to analysis. Our parts such as rotating disk, Piston, handle gears and keep them away from stress can. 4.
Mathematics:
Mathematics is heart of engineering every single element of our project have definite dominations which are calculated from derived formulas. 1.4
PRODUCTION AND MARKET EXPERIENCE
Production provides knowledge about welding, cutting and machining during production we also got knowledge about interesting facts that production requires knowledge of market experience Market knowledge reduces the expense of manufacture. We did a lot of mistakes mistakes while designing the the project. One of the biggest mistakes is is designing the project without standardized raw material.
2
The sole purpose of this project is to understand the fundamental knowledge of design and mechanism by using fulcrum system and a simple mechanism property. A mechanical tin can crusher is basically one of the most aid able machines. It helps to reduce the pollute environment of this world. Thus helps create a better place to live in. apart from that, this tin can crusher can actually be the future mode of recycles apart from the recycle bins. It can be placed everywhere, in the park, houses, even in cars. Using a similar type of a design from the diagram below, but with the added a bin bellow the tin can crusher concept of recycling can be apply. To design the mechanical part of a tin can crusher and to fabricate the Mechanical part of the system is the step to learn mechanical engineering.
1.5
PROJECT SYNOPSIS
In this project, development of a recycle bin tin can crusher so the tin can might crush as flat and look as symmetrically as possible and inserted the bin. The designs are an environment friendly and use simple mechanism properties such as fulcrum system. The design is done so that the knowledge of designing, mechanism and forces.
1.6
OBJECTIVES
і) To develop of a recycle rec ycle bin tin can crusher. іі) To fabricate recycle bin tin can crusher low cost and cost and time consuming.
1.7
SCOPE OF WORK
і) Literature review on the knowledge of mechanism design іі) To design the mechanical part of a tin can crusher using CAD software. software. ііі) Develop the model tin can crusher using bending process, welding process, drilling process and cutting process. іv) Fabricate the model tin can crusher using welding skill and machining.
3
1.8 PROBLEM STATEMENT
When people footstep the tin after finishes their drink, the tin always not look symmetrically flat and it look messy. This condition sometime makes tin produce the sharp adage will harm or injured the people. Furthermore, people always throw the can anywhere. These conditions makes pollution for this environment, become bad surrounding and separate the ditches. So this design is use to crush the can as flat as possible and try to reduce time, cost consuming and the sharp edge also have been bellow the crusher.
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CHAPTER- 2
THE MECHANISMS
We know that a machine is a device which receives energy and transforms it into some useful work. A machine consists of a number of parts or bodies. In this chapter, we shall study the mechanisms of the various parts or bodies from which the machine is assembled. This is done by making one of the parts as fixed, and the relative motion of other parts is determined with respect to the fixed part. 2.1
KINEMATIC LINK / ELEMENT
Each part of a machine, which moves relative to some other part, is known as a kinematic link (or simply link) or idly fastened together, so that they do not move relative to one another. For example, in a reciprocating steam engine piston rod and crosshead constitute one link; connecting rod with big and small end bearings constitute a second link: crank, crank shaft and fix fly wheel a third link and the cylinder, engine frame and main bearings a fourth link. A link or element need not to be a rigid body. A body is said to be a resistance body if it is capable of transmitting the required forces with negligible deformations. Thus a link should have the following two characteristics:
2.2
It should have relative motion.
It must be a resistance body.
TYPES OF LINKS
In order to transmit motion, the driver and the follower may be connected by the following three types of links:
5
Right link: A rigid link is one which does not undergo and deformation while
transmitting motion. Strictly speaking, rigid links do not exist. However, as the deformation of a connecting rod, crank etc. of a reciprocating steam engine is not appreciable; they can be considered as rigid links.
Flexible link: A flexible link is one which is partly deformed in a manner not to
affect the transmission of motion. For example, belts, ropes, chains and wires are flexible links and transmit tensile forces only.
Fluid link: A fluid link is one which is formed by having a fluid in a receptacle
and the motion is transmitted through the pressure or compression only, as in the case of hydraulic presses, jacks and brakes.
2.3
STRUCTURE
It is an assemblage of a number of resistant bodies (known as members) having no relative motion between them and meant for carrying loads having straining action. A railway bridge, a roof truss, machine frames etc., are the ex amples of structure.
2.4
DIFFERENCE BETWEEN A MACHINE AND A STRUCTURE
The following differences between a machine and a structure are important from the subject point of view:
The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another.
A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work.
The links of a machine may transmit both power and motion, while the members of a structure forces only. 6
2.5
KINEMATIC PAIR
The two links or elements of a machine, when in contact with each other, are said to form a pair. If the relative motion between them is completely or successfully constrained. (I.e. in a definite direction), the pair is known as kinematic pair.
2.6
TYPES OF CONSTRAINED MOTIONS
Following are the three types of constrained motions:
When the motion between a pair is limited
Completely constrained motion:
to a definite direction irrespective of the direction of force applied then the motion is said to be a completely constrained motion. For example, the piston and cylinder (in a steam reciprocate) relative to the cylinder irrespective of the direction of motion of the crank, as shown in fig.
Figure 2.1 Completely constrained motion
Incompletely constrained motion: When the motion between a pair can take
place in more than one direction then the motion is called an incompletely constrained motion. The change in the direction of impressed force may alter the direction of relative motion between the pair. A circular bar or shaft in a circular hole.
7
Figure2.2 Incompletely constrained motion
Successfully constrained motion: When the motion between the elements,
forming a pair is such that the constrained motion is not completed by itself, but by some other means, then the motion is said to be successfully constrained motion. Consider a shaft in a foot-step bearing as shown in Fig. 5.5. The shaft may rotate in a bearing or it may move upwards. This is a case of incompletely constrained motion. But if the load is placed on the shaft to prevent axial upward movement of the shaft, then the motion of the pair is said to be successfully constrained motion. The motion of an I.C. engine valve (these are kept on their seat by a spring) and the piston reciprocating inside an engine cylinder are also the examples of successfully motion. 2.7
MECHANISM
When one of the links of a kinematic chain is fixed, the chain is known as mechanism. It may be used for transmitting or transforming motion e.g. engine indicators. Typewriter, etc. A mechanism with four links is known as simple mechanism, and the machine with more than four links is known as compound mechanism. When a mechanism is required to transmit power or to do some particular type of work it then becomes a machine. In such cases, the various links or elements have to be designed to withstand the forces (both static and kinetic) safely. A little consideration will show that a
8
mechanism may be regarded as a machine in which each part is reduced to the simplest form to transmit the required motion. 2.8
NUMBER OF DEGREES OF FREEDOM FOR PLAN MECHANISMS
In the design or analysis of a mechanism, one of the most important concerns is the number of degrees of freedom (also called movability) of the mechanism. It is defined as the number of input parameters (usually pair variables) which must be independently controlled in order to bring the mechanism into useful engineering purpose. It is possible to determine the number of degrees of freedom of a mechanism directly from the number of links and the number and types of joints which in includes.
Figure2.3 TYPE OF BAR CHAIN
Consider a four bar chain, as shown in Fig 2.3 (a). A little consideration will show that only one variable such as 0 is needed to define the relative positions of all the links. In other words, we say that the number of degrees of freedom of a four bar chain is one. Now, let us consider a five bar chain, as shown in Fig 2.3(b). In this case two variables such as 01, and 02 are needed to define completely the relative positions of all the links. Thus, we say that the number of degrees of freedom is two. In order to develop the relationship in general, consider two links AB and CD in a plane motion as shown in Fig 2.4(a).
9
Figure2.4 LINK POSITION
The link AB with co-ordinate system OXY is taken as the reference link (or fixed link). The position of point P on the moving link CD can be completely specified by the three variables. The differential of an automobile requires that the angular velocity of two elements be fixed in order to know the velocity of the remaining elements. The differential mechanism is thus said to have two degrees of freedom. Many computing mechanism have two or more degrees of freedom. Co-ordinates of the point P denoted by x and y and the inclination 0 of the link CD with X-axis or link AB. In other words, we can say that each link of a mechanism has three degrees of freedom before it is connected to any other link. But when the link CD is connected to the link AB by a turning pair at A, as shown in Fig. 2.4 (b), the position of link CD is now determined by a single variable 0 and thus has one degree of freedom. From above, we see that when a link is connected to a fixed link by a turning pair (i.e. lower pair), two degrees of freedom are destroyed. This may be clearly understood from Fig 2.5 in which the resulting four bar mechanism has one degree of freedom (i.e. n= 1)
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Figure2.5 DEGREE OF FREEDOM
Now let us 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 ( I - 1) and thus the total number of degrees of freedom will be 3 ( I -1) before they are connected to any other link. In general, a mechanism with / number of links connected connected by j number of binary joints or lower pairs (i.e. single degree of freedom pairs) and h number of higher pairs (i.e. two degree if freedom pairs) then the number of degrees of freedom of mechanism is given by. n = 3 ( I - 1) - 2 j – h This question is called Kutzbach criterion for this movability of a mechanism having plane motion. If there are no two degree of freedom pairs (i.e. higher pairs). then h = 0. Substituting h = 0 in equation (i) we have n = 3 ( I - 1) - 2j
2.9 MOVEMENT OF INETIA OF A DISK
Case is about an axes passing through center and 1 to plane o disk M= mass of disk R= 2
Radius of disk Square area of disk = IIR Mass/area of disk =
M 2
πR
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The whole disk can be considered to be made up of a very large no of rings whose radius varies from a to R: consider one such ring of radius X and thickness dx. Hence, mass of ring =
M
x 2II x dx. 2
πR
2
M.I. of this ring about the given axes:- Mass x (radius)) = 2 m.x dx x
x2
2
R
To find M.I. of whole disk we I this expression from x = 0 + o x = R. 3
I =
= Nx dx 2
R =>
I
= 2M 2
R
4 R
= 2M
{x}
2
R
= M
4
4
(R - )
2
R
4
=> M.I. = M x R 2
2R =>M. I = 1
2
MR
(6)
2
12
The title development of recycle bin tin can crusher requires an amount of good understanding on the knowledge of the science. Therefore, executing a research is necessary to obtain all the information available and related to the topic. The information or literature reviews obtained are essentially valuable to assist in the construction and specification of this final year project. With this grounds established, the project can proceed with guidance and assertiveness in achieving the target mark.
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CHAPTER- 3
LITERATURE REVIEW
3.1
TERMINOLOGY
Can recycling is a very important part of any family and community recycling program. Aluminum recycling is one of the easiest things you can do to help the environment. Recycling of can began long ago and started to become common place back in the early 1970s. Can is 100% renewable. This means that the can you take to your local recycling center today becomes a new aluminum can. There are no waste products in the process of making aluminum a 100% renewable resource and one of the best things you can recycle. You might be surprised to know that within 60 days an aluminum can is able to go from your recycling center and become a brand new can to be used by consumers. Recycle bin tin can crusher use to crush tin can. Tin can crusher will help community to crush the tins. Crusher also can less the using of force and avoids causing injury. This Crusher will clipped the plate above and below of the tin. Then, the tin will be pressed by the plate till the sufficient force was imposed and lastly the tin crush.
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3.2
TYPES OF TIN CAN CRUSHER
Figure 3.1: SEVERAL TIN CAN CRUSHER
3.3
CRUSHER
A crusher is a machine designed to reduce large solid material objects into a smaller volume, or smaller pieces. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different composition can be differentiated. 15
Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel or tangent solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other. The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil. Querns and mortars are types of these crushing devices.
3.4
TYPES OF CRUSHER
The most common types of crusher these days are basically used for help people. The design of these types enable them to crush follow the types of crusher and then crush as look as possible or destroy. These crusher types are jaw crusher, gyratory crusher and impact crusher.
3.4.1 Jaw Crusher
A jaw or toggle crusher consists of a set of vertical jaws, one jaw being fixed and the other being moved back and forth relative to it by a cam or pitman mechanism. The jaws are farther apart at the top than at the bottom, forming a tapered chute so that the material is crushed progressively smaller and smaller as it travels downward until it is small enough to escape from the bottom opening. The movement of the jaw can be quite small, since complete crushing is not performed in one stroke. The inertia required to crush the material is provided by a weighted flywheel that moves a shaft creating an eccentric motion that causes the closing of the gap. Single and double toggle jaw crushers are constructed of heavy duty fabricated plate frames with reinforcing ribs throughout. The crusher’s components are of high strength design to accept high horsepower draw. Manganese steel is used for both fixed and movable jaw faces. Heavy flywheels allow crushing peaks o n tough materials. Double Toggle jaw crushers may feature hydraulic toggle adjusting mechanisms. 16
Figure 3.2: JAW CRUSHER
3.4.2 Gyratory Crusher
A gyratory crusher is similar in basic concept to a jaw crusher, consisting of a concave surface and a conical head; both surfaces are typically lined with manganese steel surfaces. The inner cone has a slight circular movement, but does not rotate; the movement is generated by an eccentric arrangement. As with the jaw crusher, material travels downward between the two surfaces being progressively crushed until it is small enough to fall out through the gap between the two surfaces. As an example, a FullerTraylor gyratory crusher features throughputs to 12,000 TPH with installed powers to 1,300 HP.
17
Figure 3.3: GYRATORY CRUSHER
3.4.3 Impact Crushers
Impact crushers involve the use of impact rather than pressure to crush material. The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape. This type of crusher is usually used with soft and non-abrasive material such as coal, seeds, limestone, gypsum or soft metallic ores.
Figure 3.4: IMPACT CRUSHER 18
CHAPTER- 4
COMPONENTS OF AUTOMATIC CAN CRUSHER
The following are the components of automatic can crusher.
1.
BASE
2.
SHAFTS
3.
BEARINGS
4.
GEARS
5.
CRUSHING UNIT
6.
DISK
7.
CONNECTING ROD
8.
POWER DRILL
9.
BEVEL GEAR ASSEMBLY
19
TABLE OF MATERIAL USED
SR. NO.
ITEMS
QUANTITY
SIZE
MATERIAL
1
ANGLE
12 FT
32*32*3
MILD STEEL
2
BOARD
1 NOS.
3*2 SQ. FT
WOOD
3
SHAFT
4 FT
20 MM
MILD STEEL
4
BEARINGS
6 NOS.
P 204
----
5
DISK
1 NOS.
8 INCH DIA
MILD STEEL
6
CONNECTING ROD
1 NOS.
15 INCH
MILD STEEL
7
SLIDER
I NOS
9 NICH (C)
MILD STEEL
TABLE – 4.1
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4.1
BASE
The base is the rectangular piece of plywood. It is the stationary & rigid part of the machine. Since machine consist of rotating parts which often produces vibrations when rate of excessive vibrations produced by the rotating parts of the machine.
It also
provides the rigid support to the rotating part of the machine.
Figure 4.1 PLYWOOD BASE
4.2
SHAFTS
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. 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
21
words, we may say that a shaft is used for the transmission of torque and bending moment. The various members are mounted on the shaft by means of keys or splines.
Figure 4.2 STEEL SHAFT
1.
The shafts are usually cylindrical, but may be square or cross-shaped in section.
They are solid in cross-section but sometimes hollow shaft are also used. 2.
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. 3.
A spindle is short shaft that imparts motion either to a cutting tool (e.g. drill press
spindles) or to a work piece (e.g. lathe spindles).
4.2.1
MATERIAL USED FOR SHAFTS The material used for shafts should have the following prop erties: 1.
It should have high strength.
2.
It should have good mach inability.
3.
It should have low notch sensitivity factor. 22
4.
It should have good heat treatment properties.
5.
It should have high wear resistant properties.
The material used for ordinary shafts is carbon steel of grades 40C8, 45C8, 50C4, and 50C12. The mechanical properties of these grades of carbon steel are given in the following table. Table: Mechanical properties of steels used for shafts.
Indian standard
Ultimate tensile strength,
Yield strength (MPa)
designation
(MPa)
40C8
560-670
320
40C8
610-700
350
50C4
640-760
370
50C12
700 Min.
390
TABLE – 4.2
When a shaft of high strength is required, then alloy steel such as nickel, nickelchromium or chrome-vanadium steel is used. 4.2.2
MANUFACTURING OF SHAFTS
Shafts are generally manufactured by hot rolling and finished to size by cold drawing or turning and grinding. The cold rolled shafts are stronger than hot rolled shafts but with higher resident stresses. The residual stresses may cause distortion of the shaft when it is machined, especially when slots or keyways are cut. Shafts of larger diameter are usually forged and turned to size in a lathe.
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4.2.3
TYPES OF SHAFTS
The following two types of shafts are important from the subject point of view: 1.
Transmission shafts: These shafts transmit power between the source and the
machines absorbing power. The counter shafts, line shafts, over head 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.
4.2.4 STANDARD SIZES OF TRANSMISSION SHAFTS The standard sizes of transmission shafts are: 25mm to 60mm with 5mm steps; 60mm to 110mm steps; 110mm to 140 mm with 15mm steps; and 140mm to 500mm with 20mm steps. The standard length of the shafts is 5m, 6m and 7m. 4.2.5
DESIGN OF SHAFTS
The shafts may be designed on the basis of 1. Strength, and 2. Rigidity and stiffness. In designing shafts on the basis of strength, the following cases ma y be considered: (a)
Shafts Subjected to twisting moment or torque only.
(b)
Shafts subjected to bending moment only.
(c)
Shafts subjected to combined moment only.
(d)
Shafts subjected to axial loads in addition to combined torsional and bending loads. We shall now discuss the above cases, in detail, in the following pages
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4.3
DISK
The disk is that rotating element of the mechanism which converts the rotating motion into sliding motion. The disk is the main part of the mechanism. It also works as fly wheel which store energy in power stock & provide energy in returns stock. It is also made up o mild steel. 4.3.1
Rotary motion to translator motion
The conversion from rotary motion of the disk to the translator motion of the piston & connecting rod is achieved by placing an eccentric point on the disk shown below
Figure 4.3 DISK
With the rotation of disk around its centre the point revolute around that centre of disk. Hence we can say that rotation of disk produces revolution of eccentric point which forces the piston forward & background by the mean of connecting rod and connecting rod hence stock is produced by the piston.
25
Figure 4.4 ECCENTRIC POINT
4.4
THE CONNECTING ROD
The connecting rod is that element of the mechanism which transfer motion from one end of the connecting rod is connected to the end of the slide piston while the other end is connected to the disk. The material used for the connecting rod is mild steel.
4.4.1
Calculating the length of connecting Rod.
The length of connecting rod should never be less than the diameter of the stroke length generated by the disk is equals to the twice the radius of the disk i.e. diameter. The second factor that matters for the length of the connecting road is the space (or distance) between the rotating part and the sliding part. In our case it’s the distance between the disk & the end of the sliding piston so the total length of the connecting rod
26
is the sum of the distance between end of the sliding piston & the disk eccentric point & the diameter of the disk.
4.5
BEARINGS
Figure 4.5 BEARINGS
27
4.5.1
INTRODUCTION
The term "bearing" is derived from the verb "to bear", a bearing being a machine element that allows one part to bear (i.e., to suppo rt) another. A bearing is a device that is used to enable rotational or linear movement, while reducing friction and handling stress. Resembling wheels, bearings literally enable devices to roll, which reduces the friction between the surface of the bearing and the surface it’s rolling over. It’s significantly easier to move, both in a rotary or linear fashion, when friction is reduced — this also enhances speed and efficiency. Also a bearing is a machine element that constrains relative motion between moving parts to only the desired motion. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.
4.5.2
WORKING – HOW IT WORKS?
In order to serve all these functions, bearings make use of a relatively simple structure: a ball with internal and external smooth metal surfaces, to aid in rolling. The ball itself carries the weight of the load —the force of the load’s weight is what drives the bearing’s rotation. However, not all loads put force on a bearing in the same manner. There are two different kinds of loading: radial and thrust.
A radial load, as in a pulley, simply puts weight on the bearing in a manner that causes the bearing to roll or rotate as a result of tension. A thrust load is significantly different, and puts stress on the bearing in an entirely different way. If a bearing (think of a tire) is flipped on its side (think now of a tire swing) and subject to complete force at that angle (think of three children sitting on the tire swing), this is called thrust load. A bearing that is used to support a bar stool is an example of a bearing that is subject only to thrust load.
28
Many bearings are prone to experiencing both radial and thrust loads. Car tires, for example, carry a radial load when driving in a straight line: the tires roll forward in a rotational manner as a result of tension and the weight they are supporting. However, when a car goes around a corner, it is subject to thrust load because the tires are no longer moving solely in a radial fashion and cornering force weighs on the side of the bearing.
4.5.3 TYPES OF BEARINGS
There are numerous different kinds of bearings that are designed to handle radial load, thrust load, or some combination of the two. Because different applications require bearings that are designed to handle a specific kind of load and different amounts of weight, the differences between types of bearings concern load type and ability to handle weight.
1) BALL BEARINGS
6) SPECIALIZED BEARINGS
2) ROLLER BEARINGS
TYPES OF BEARINGS 5) TAPERED ROLLER BEARINGS
3) BALL THRUST BEARINGS 4) ROLLER THRUST BEARINGS
Figure 4.6 TYPES OF BEARINGS
29
1) BALL BEARINGS
Ball bearings are extremely common because they can handle both radial and thrust loads, but can only handle a small amount of weight. They are found in a wide array of applications, such as roller blades and even hard drives, but are prone to deforming if they are overloaded.
Figure 4.7 BALL BEARINGS APPLICATIONS 1) Rolling friction is provided by a ball. 2) Low friction, high speed, light to medium loading. 3) Light and general machine applications. 4) Commonly found in fans, roller blades, wheel be arings, and under hood
applications on cars etc.
2) ROLLER BEARINGS Roller bearings are designed to carry heavy loads — the primary roller is a cylinder, which means the load is distributed over a larger area, enabling the bearing to handle larger amounts of weight. This structure, however, means the bearing can handle primarily radial loads, but is not suited to thrust loads. For applications where space is an issue, a needle bearing can be used. Needle bearings work with small diameter cylinders, so they are easier to fit in smaller applications.
30
Figure 4.8 ROLLER BEARINGS APPLICATIONS 1) In this the rolling function is provided by a cylinder of some kind. May also be referred to as needle roller bearings (where length is mu ch greater than diameter) 2) Low friction, medium to heavy radial loading. 3) Commonly found in general machine applications including gearboxes and transmissions, machine tool construction equipment.
1) BALL THRUST BEARINGS These kinds of bearings are designed to handle almost exclusively thrust loads in low-speed low-weight applications. Bar stools, for example, make use of ball thrust bearings to support the seat.
Figure 4.9 BALL THRUST BEARINGS
2) ROLLER THRUST BEARINGS Roller thrust bearings, much like ball thrust bearings, handle thrust loads. The difference, however, lies in the amount of weight the bearing can handle: roller thrust bearings can support significantly larger amounts of thrust load, and are therefore
31
found in car transmissions, where they are used to support helical gears. Gear support in general is a common application for roller thrust bearings.
Figure 4.10 ROLLER THRUST BEARINGS
3) TAPERED ROLLER BEARINGS
This style of bearing is designed to handle large radial and thrust loads — as a result of their load versatility, they are found in car hubs due to the extreme amount of both radial and thrust loads that car wheels are expected to carry.
Figure 4.11 TAPERED ROLLER BEARINGS
APPLICATIONS 1) A tapered version of a roller bearing is used for combined axial and radial loads, such as in wheel applications on truck.
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2) Commonly found in heavy industrial, truck and wheel applications with combined radial and axial loads. Some examples are manual transmissions, gearboxes, power generation and other process equipment.
4) SPECIALIZED BEARINGS There are, of course, several kinds of bearings that are manufactured for specific applications, such as I.
MAGNETIC BEARINGS are found in high-speed devices because it has
no moving parts — this stability enables it to support devices that move unconscionably fast.
Figure 4.12 MAGNETIC BEARINGS
II.
GIANT ROLLER BEARINGS are used to move extremely large and
heavy loads, such as buildings and large structural components.
Figure 4.13 GIANT ROLLER BEARINGS
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4.6
CAN CRUSHING UNIT
Can crushing unit is that part of assembly where the cons & big size are forced enough so that they can compress into small pieces. The crushing unit consists of two parts
The fixed or rigid assembly
The sliding Unit
1.
The fixed assembly: It is like a C channel which has been cut to desirable
shape and size. This fixed assembly is to connected to base by two support. These supports provide rigidity to the fixed cylinder. Since assembly is fixed therefore sliding unit can apply the enough force so as to crush the can into small pieces.
2.
The Sliding Unit: The shape of slider is obtained by a small rectangle with
removed faces. These types of shape add one unique feature to the crusher assembly one end of the slider is attached to the connecting rod which transfer the power coming from the disk to the slider while the other end crusher the can. The main purpose of the sliding unit is to keep the motion of the sliding piston in straight line. Since connecting rod have two degree of freedom i.e. it can have motion in two directions is
Rotation: - It rotates in the plane passing through a xis of crushing unit.
Translation: - It move forward & backward in the plane discussed above.
But at the end of connecting we need only one degree of freedom is second one i.e. pure sliding. Therefore we need a sliding unit which can restrict the rotation of connecting rod and posse's only sliding motion.
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CHAPTER - 5
THE GEARS 5.1
FRICTION WHEELS
The motion and power transmitted by gears is kinematically equivalent to that transmitted by frictional wheels or dies. In order to understand how the motion can be transmitted by two toothed wheels, consider two plain circular wheels A and B mounted on shafts. The wheels have sufficient rough surfaces and press against each other as shown in Fig. 5.1
Figure 5.1 FRICTION WHEELS
Let the wheel A is keyed to the rotating shaft and the wheel B to the shaft to be rotated. A little consideration will show that the wheel A is rotated by a rotating shaft, it will rotate the wheel B in the opposite direction as shown in Fig. 5.1. The wheel B will be rotated by the wheel A so long as the tangential force exerted by the wheel A does no t exceed the maximum frictional resistance between the two wheels. But when the tangential force (p) exceeds the *frictional resistance (f), slipping will take place between the two wheels. 35
Figure 5.2 GEAR MESHING
In order to avoid the slipping, a number of projections (called teeth) as shown in Fig. are provided on the periphery of the wheel A which will fit into the corresponding recesses on the periphery of the wheel B. A friction wheel with the teeth cut on it is known as gear or toothed wheel. The usual connection to show the toothed wheels is by their pitch circles. 5.2
Advantages and Disadvantages of Gear Drives
The following are the advantages and disadvantages of the gear drive as compared to other drives, i.e. belt, rope and chain drives:
It transmits exact velocity ratio.
It may be used to transmit large power.
It may be used for small centre distances of shafts.
It has high efficiency.
It has reliable service.
It has compact layout.
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5.3
Disadvantages
Since the manufacture of gears requires special tools and equipment, therefore it is costlier than other drives.
The error in cutting teeth may cause vibrations and noise during operation.
It requires suitable lubricant and reliable method of applying it, for the proper operation of gear drives.
5.4
Condition for Constant Velocity Ratio of Gears-Law of Gearing
Consider the portions of the two teeth, one on the wheel I (or pinion) and the other on the wheel as shown by thick line curves in Fig. 5.3. Let the two teeth come in contact at point Q, and the wheels rotate in the directions as shown in the figure. Let TT be the common tangent and MN be the common normal to the curves at point of contact from the centres O1 and O2, draw O1M and O2N perpendicular to MN. A little consideration will show that the point Q moves in the direction QC, when considered as a point on wheel 1, and in the direction QD when considered as a point on wheel2.
Figure 5.3 LAW OF GEARING 37
Let V1 and V2 be the velocities of the point Q on the wheels 1 and 2 respectively. If the teeth are remain in contact, then the components of these velocities being the common normal MN must be equal. =>
v1 cos α = v2 cos β
=> (ω1 x O1Q) cos α = (ω2 x O2Q) cos β => (ω1 x O1Q) O1M = (ω2 x O2Q) O2 N O1Q
=>
ω1 ω2
O2Q
=
O2 N
O1M
...(i)
Also from similar triangles O 1MP and O2 NP =>
O2 N = O2P O1M
...(ii)
O1P
Combining equations (i) and (ii), we have =>
ω1 ω2
=
O2 N = O2P O1M
....(iii)
O1P
We see that the angular velocity ratio is inversely proportional to the ratio of the distance of P from the centers Q1 and Q2, or the common normal to the two surfaces at the point of contact Q intersects the line of centers at point P which divides the centers distance inversely as the ratio of angular velocities. Therefore, in order to have a constant angular velocity ratio for all positions of the wheels, P must be the fixed point (called pitch point) for the two wheels. In order words, the common normal at the point of contact between a pair of the teeth must always pass through the pitch point. This is fundamental condition which must be satisfied while designing the profiles for the teeth of gear wheels. It is also known as law of gearing.
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5.5
Two speed out come.
The Gears are used to get the two different speeds on the machine which is described as under. 1
High Power Speed
2.
Low Power Speed
1
High Power Speed: High power speed is designed to crush harder cons. In this
case the effort applied by the Human is utilized only to crush the can. Some cans have to crush & need more compression power to crush then for them this speed is sufficient. To obtain such speed the gear ratio should be one or even below one. The lower the value of the gear ratio the smooth obtained.
As the result of lower gear ratio the
operating speed of the machine will also lower down. Since we have designed the machine to compress the cans i.e. one in forward stroke & one in backward stroke. In this way by using the gear ratio equals to one we get two can crush per cycle of the machine. 2.
LOW POWER SPEED: - In this speed the Human efforts is utilized to crush the
can as well as to increase the speed of machine i.e. crushing the cans at faster rate. Since if some human effort is used in both the speeds the crushing power of formal speed would we low. To obtain low power high machining speed we use the gear ratio greater them one i.e. or more. In our case we use the gear ratio for b w power speed is as a result of this we get four cans crushed in one cycle i.e. machining rate is doubled.
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5.6 Calculation RPM of Drill
=
2600 rpm
No. of Teeth on Smaller Gear (N1)
=
19
No. of teeth on Bigger Gear (N2)
=
75
Gear Ratio
=
N2/N1=4:1 approx.
Rpm of shaft (1)
=
867 rpm
Rpm of shaft (2)
=
217 rpm
Rpm of shaft (3)
=
54
Disk diameter
=
8 inch
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CHAPTER
– 6 CONCLUSION
We learned from this project that designing is not easy job. Many factors have to be considered also the calculations to be repeated many times. This needs a team effort and more experience since we are students for that ou r project is limited. We spent in this project more time in each activity from organizing the time table then the project selection. After we selected the project we progressed to model it and calculate many component by helping of computer aided design. In this project we learned a lot but we still need to learn more and more before us becoming more professional designer. The design activities were so enjoyable and interesting because our project objective will help our country to recycle the cans and gain the benefit in the economy side and environmental side. In three months which the time for our project we focused to model the project design in the computer aided design (CAD) and make calculations for some components. In our project the main component was the gears design. In this project, we learned very useful knowledge in designing machines especially the computer aided design. We learned how properly created schedule and take the responsibility of time keeping and activity control.
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