Design And Fabrication Project Wave Motion Of Cam Engineering Essay

This undertaking deals with the design and fiction of wave gesture of Cam. The setup consists of 18 Cams which are made in contact with 18 several level face equal length followings. The face angles for back-to-back Cams are 45 grades. Thus the followings move in a sinusoidal moving ridge. The graph is plotted between the face angle and the follower supplanting. The design is about same to the Cam shaft in the car engine. This construct is fundamentally applied in the car engines, vessel engines etc. This rule can be used in reciprocating machine parts traveling in the moving ridge gesture.

Introduction

A Cam is a mechanical constituent of a machine that is used to convey gesture to another constituent, called the follower, through a prescribed gesture plan by direct contact.

A Cam mechanism consists of three elements: the Cam, the follower ( or follower system ) , and the frame. The follower is in direct contact with the Cam. The Cam may be of assorted forms. The follower system includes all of the elements to which gesture is imparted by the Cam. This may be connected straight to the follower, or connected through linkages and pitching. The frame of the machine supports the bearing surfaces for the Cam and for the follower.

Uses of Cam

The Cam mechanism is a various 1. It can be designed to bring forth about limitless types of gesticulating the follower. It is used to transform a rotary gesture into a translating or hovering gesture. On certain occasions, it is besides used to transform one translating or hovering gesture into a different translating or hovering gesture.

River cams are used in a broad assortment of automatic machines and instruments. Typical illustrations of their usage include textile machineries, computing machines, publishing imperativenesss, nutrient processing machines, internal burning engines, and countless other automatic machines, control systems and devices. The Cam mechanism is so a really of import constituent in modern mechanisation.

Categorization of Cams

River cams can be handily classified into two chief groups:

Group a:

River cams that impart gesture to the follower in a plane in line with the axis of rotary motion of the Cam ( as does a cylindrical Cam ) .

Group B:

River cams that impart gesture to the follower in a plane at 90 grades to the axis of rotary motion, as with face or border Cams. Most cams autumn into this class.

The Cam, as a agency of bring forthing a given type of gesture, is simple and sensible to plan, provided the simple rules are understood. Another advantage is that, by and large, a Cam can easy be changed or modified to let a alteration of gesture, without interfering with the balance of the mechanism.

Bizarre Cam

A round Cam is frequently called an bizarre Cam because the axis of rotary motion of the Cam is offset from the geometric centre of the round phonograph record.

Concentric phonograph record

A homocentric phonograph record attached to a rotating shaft would hold its axis of rotary motion co-occuring with its geometric centre.

Edge Cams

It must be appreciated that this type of Cam, where the follower is in contact with the border of the Cam phonograph record, is merely capable of leaving positive gesture to its follower in one way, that is, during the rise part of the cam motion. During the autumn part of the Cam motion the follower must be maintained in contact with the Cam either by the mass of the follower and its mechanism or, more normally, by a spring. Both methods have their advantages.

Box Cam

A channel can be milled in the face of cam phonograph record. As the Cam rotates, a follower located in the channel has its gesture guided by the channel. This type of Cam is called a box Cam.

Cylindrical Cams

Cylindrical Cams are used when gesture has to be transmitted parallel to the axis of rotary motion of the Cam. The cylindrical or barrel Cam consists of a revolving cylinder with a coiling ( sleep together shaped ) channel in its curving surface. A follower with a tapering roller terminal is located in the channel. As the cylinder turns, the follower moves in a consecutive line analogue to the axis of the rotary motion barrel Cam. This type of Cam is frequently used to steer yarn on run uping machines, looms and fabric doing machines.

PROFILE SHAPES OF SOME CAMS

The most common sort of Cam is the home base Cam. It consists of a narrow home base or phonograph record, which is fixed to a rotating shaft. The home base is shaped so that the follower will bring forth a pre-determined signifier of gesture. Most Cams are designed to hold a smooth curving form so that the gesture transmitted to the follower is smooth and without sudden dorks.

Pear-shaped CAMS

These type Cams are frequently used for commanding valves. For illustration, they are used on motor auto camshafts to run the engine valves. A follower controlled by a pear-shaped Cam remains inactive for about half a revolution of the Cam. During the clip that the follower is stationary, the Cam is in a dwell period. During the other half revolution of the Cam, the follower rises and so falls. As the pear-shaped Cam is symmetrical, the rise gesture is the same as the autumn gesture.

CIRCULAR CAMS

These Cams are sometimes called bizarre Cam. The Cam profile is a circle. The centre of rotary motion of the Cam is frequently from the geometric centre of the circle. The round Cam produces a smooth signifier of gesture called a simple harmonic gesture. These Cams are frequently used to bring forth gesture in pumps. Round Cams are frequently used to run steam engine valves. As the Cam is symmetrical, the rise and autumn gestures are the same.

HEART SHAPED CAMS

This Cam causes the follower to travel with a unvarying speed. Cordate Cams are indispensable when the follower gesture demands to be unvarying or steady as, for illustration, in the mechanism that winds thread equally on the spool of a sewing machine. A cordate Cam can be used for weaving wire equally on the former of a solenoid.

UNIFORM ACCELERATION AND RETARDATION CAMS:

A Cam shaped as shown controls the gesture of the follower so that it moves with unvarying acceleration and deceleration. The follower additions and looses speed at a changeless rate. Uniform acceleration and deceleration Cams are used to command the gesture of linkages in complex machinery.

CAM Followings

There are three types of Cam followings, and since the type of follower influences the profile of the Cam it is worthwhile sing the advantages and disadvantages of each type. The three types are the knife-edge, the roller follower and the patrolman or mushroom follower.

The knife border follower

This is the simplest type, is non frequently used due to the rapid rate of wear. When it is adopted, it is normally for reciprocating gesture, running in slides and there is considerable side push, this being a constituent of the push from the Cam.

The roller follower

This eliminates the job of rapid wear since the skiding consequence is mostly replaced by a roller action. Some sliding will still take topographic point due to the changing peripheral velocity of the Cam profile, due to the altering radius of the point of contact. Note besides that the radial place of the contact between the Cam and the roller, comparative to the follower centre, will alter harmonizing to whether a rise or autumn gesture is taken topographic point: this fact has to be considered when building the Cam profile. Again, with the roller follower, considerable side pushs are present, a disadvantage when covering with reciprocating gestures. This side push will be increased when utilizing little rollers.

The level pes or mushroom follower

This has the advantage that the lone side push nowadays is that due to the clash between the follower and the Cam. The job of wear is non so great as with the knife-edge follower, since the point of contact between the Cam and follower will travel across the face of the follower harmonizing to the alteration of form of the Cam. A fast one to decrease farther the consequence of wear is to plan the follower to be capable of axial rotary motion and set up the axis of the follower to lie to one side of the Cam. Thus the contact with the Cam will be given to do rotary motion of the follower. The Cam profile, to work with a patrolman follower, must be convex at all parts, in order to forestall the corners of the follower delving into the Cam profile. The minimal Cam radius should be every bit little as possible to minimise sliding speed and clash.

Three types of Cam followings

CAM DESIGN CONSIDERATIONS

All three types of Cam followings can be mounted in the undermentioned ways:

1 ) In-line with the Cam centre line,

2 ) Offset from the Cam centre line, or

3 ) Mounted on a singing radial arm.

All Cam followings wear at different rates depending on the follower form, size, type etc. the following subdivision shows how to cut down wear in a flat-foot follower.

Get the better ofing opposition to cam gesture

When utilizing a spring anchored to a fixed point, the force exerted by the spring will change during the camshaft revolution, making a upper limit when the follower is at the full diameter of the Cam and the spring at its maximal extension. The camshaft thrust has to get the better of this increasing opposition to rotary motion. During the autumn part of the Cam gesture, the spring burden ( which is diminishing ) is be givening to force the Cam unit of ammunition, helping rotary motion. These conditions give rise to imbalanced torsion ( turning minutes ) demands from the camshaft driving motor. Using a double-arm Cam lever with two followings, one on each arm and each running on its Cam, can extinguish this fluctuating burden. The Cam must be designed to fit each other, the 2nd Cam lifting when the first Cam falls, but attention must be taken to supply a little sum of clearance: when one Cam is driving, the other follower must be somewhat clear of its Cam. This is to guarantee that the followings do non lock when go throughing over extremums. This trouble can be eliminated if two separate weaponries, with followings on two copulating Cams, are used, the weaponries being spring-loaded together. This will give an about changeless spring length during the camshaft revolution.

Cam gestures

When the Cam turns through one gesture rhythm, the follower executes a series of events dwelling of rises, dwells, and returns. Rise is the gesture of the follower off from the Cam centre ; dwell is the gesture during which the follower is at remainder ; and return is the gesture of the follower toward the Cam centre. When a interior decorator is developing a Cam profile to bring forth a certain gesture, the information available to him/her would surely include the sum of motion required by the follower ( the supplanting ) .

The clip available in which this motion is to be carried out, and the angular velocity of the camshaft ( assumed to be changeless, as it normally is ) . He/she would besides be cognizant of the type of gesture and its features most likely to be suited for his peculiar intent. It has already been seen that, to appreciate the forces moving on the Cam and its follower, it is necessary to cognize the accelerations imparted to the follower. From the clip available and the r.p.m. of the camshaft, it is possible to cipher the figure of grades of camshaft rotary motion available to transport out the gesture. In order to hold a complete image of this information it is advisable to build a displacement-time, velocity-time, and acceleration-time graph for the gesture. From these figures it is possible to estimate the disadvantages probably to happen in pattern.

The characteristics that should be appreciated in any design are:

· Low acceleration and slowing values at the beginning and terminal of the shots, to lesson the spring lading necessary to keep contact between Cam and follower.

· No abrupt alterations in acceleration.

· Low multitudes to be moved.

These characteristics are more critical as the velocity of the Cam is increased and several standard types of gesture are used. Three types of gesture will be considered following.

DISPLACEMENT DIAGRAMS

Design demands in the portion of the machine under consideration will order the type of motion required in the Cam follower. This is so translated into the profile of a Cam, which will give the follower the needed gesture. When planing this profile the motion of the follower is normally considered in four separate subdivisions: the period when the follower is at the underside of its motion, called the underside dwell ; the motion required during the rise or lift of the follower ; the period when the follower remains at the top of its motion, called the top dwell ; and the motion required when the follower returns to the bottom place. There are three different types of follower gesture in standard usage, which is shown below.

Uniform ( changeless ) speed

Since the speed is changeless, the supplanting diagram will be a consecutive line with changeless incline and the speed diagram rectangular with zero acceleration. However, to accomplish this speed instantly at the beginning of the gesture, and keep it until the really terminal of the shot, would necessitate boundlessly high accelerations and declarations for boundlessly short periods of clip at the beginning and terminal of the shot. This of class is impossible. To cut down these peak accelerations and declarations and to do the gesture possible the conditions are modified to include a short period of unvarying acceleration and slowing at the beginning and terminal of the gesture. This means that the follower moves with unvarying speed for most of the shot, parabolic or round discharge being introduced at the beginning and terminal of the supplanting diagram. Despite these alterations it can be seen that, sing the conditions antecedently laid down, the high accelerations, peculiarly those at the terminal of the surpassing shot and the beginning of the autumn shot, require heavy springing to guarantee uninterrupted contact between border Cam and follower.

Simple harmonic gesture

The supplanting diagram is a sine curve and if a Cam is produced from this curve merely ( i.e. devoid of top and bottom dwell ) it will hold lobes of round signifier. Consideration shows that this type of Cam will give the smoothest alteration of gesture in the follower. An bizarre Cam transmits simple harmonic gesture to the follower. Examples of simple harmonic gesture from mundane life are the up and down gesture of a cork bobbing on the moving ridges on a pool, and the hovering gesture of a pendulum weight as it swings from side to side, as shown below.

Another illustration of simple harmonic gesture is the projection ( or shadow ) of unvarying round gesture onto a consecutive line. If we view from above, a plaything train engine traveling around a round path, we will see round gesture. But if we look at the shadow of the train dramatis personae by a lamp edge-on to the path, the engines shadow appears to hover back and Forth. The shadow is said to be traveling in simple harmonic gesture which is shown below.

Simple harmonic gesture follower public presentation graph

Uniform acceleration and deceleration.

This supplanting curve is parabolic. It gives a unvarying rate of acceleration from the start to the center and a similar unvarying rate of deceleration from the center to the terminal of the motion.

Drawing CAM PROFILES

Uniform speed with a knife-edge follower

Cam informations

In-line knife border follower,

50 mm minimal diameter,

40 mm lift ( rise ) with unvarying speed,

0 grades to 90 grades bottom dwell, 90 grades to 180 grades rise,

180 grades to 270 grades top dwell, 270 grades to 360 autumn,

clockwise rotary motion.

Simple harmonic gesture with a roller follower

Cam informations

In-line roller follower, diameter 12 millimeter,

minimal Cam diameter 50 millimeter,

entire rise 42 millimeter, both rise and autumn have simple harmonic gesture,

0 to 90 grades bottom dwell,

90 to 180 grades rise with simple harmonic gesture,

180 to 270 grades top dwell,

270 to 360 grades fall with simple harmonic gesture,

because this is a symmetrical Cam it can revolve in either way.

Uniform acceleration and deceleration with an slope level face follower

Cam informations,

In-line level face follower,

minimal Cam diameter 50 millimeter,

rise 36 millimeter through 180 grades and a similar autumn, both holding U.A.R. ,

this produces a symmetrical Cam giving the needed follower gesture with either way of rotary motion.

Uniform acceleration and deceleration and unvarying speed, with a knife-edge follower

Cam informations,

In-line knife border follower,

minimal Cam diameter 50 millimeter,

rise 42 millimeter through 180 grades with unvarying acceleration and deceleration,

autumn 42 millimeter through 180 grades with unvarying speed,

clockwise rotary motion.

Uniform speed with offset roller follower

Cam informations

minimal Cam diameter 50 millimeter,

underside dwell 0 to 60 grades, rise 60 to 150 grades, top dwell 150 to 210 grades, autumn 210 to 300 grades 300 to 360 grades bottom dwell,

entire lift 36 millimeter, unvarying speed, clockwise rotary motion, roller follower diameter 12 millimeter,

offset 20 millimeters to the right of the Cam center line.

Uniform speed with a radial arm roller follower

Cam informations

roller follower diameter 16 millimeter, mounted on a radial arm to the dimensions given,

full lift of roller 0 to 180 grades, top dwell 180 to 270 grades, autumn 270 to 360 grades, unvarying speed,

clockwise rotary motion,

Design of the Apparatus

Calculations

Design:

Cam

Type of the Cam used: Round phonograph record Cam

Diameter of the Cam: 44.45mm

Diameter of the Hole: 5 millimeter

Number of Cams used: 18

Off-set of the hole: 10mm

Follower:

Type of the follower used: Flat-face follower

Length of the rod: 152.4 millimeter

Number of followings used: 18

Diameter of the follower: 3mm

Spindle length: 30.48mm

Thickness of the spindle: 5mm

Distance between the followings: 5mm

Calculations:

Face angle between the Cams: 45o

Maximal supplanting of follower: 22mm

Lift of the follower: 23mm

From the graph plotted:

We get

Amplitude = 9mm

One rhythm = 360o

Supplanting of dead set measuring rods:

The difference in the supplanting of the set mensurating rods is as follows

Maximal distance between back-to-back rods: 95mm

Minimal distance between back-to-back rods: 55mm

Therefore the setup can be used besides for the longitudinal moving ridge gesture.

Cost OF ESTIMATION

Materials

Measure

Cost IN RUPEES

Cam

18

18 X 60 = 720

Flat face follower

18

18 X 20 = 360

Frame

1

400

Shaft

1

80

Manage

1

20

Wooden base

1

60

Entire

1640