review and summary

REVIEW AND SUMMARY

• A cam is a rotating mechanical member used for transmitting desired motion to a follower by direct contact.

• The cams can be classified according to their shapes as

1. Radial (or disc or plate) cams,

2. Wedge (or flat) cams,

3. Cylindrical (or barrel) cams,

4. Conical cams,

5. Globoidal cams, and

6. End (or face) cams.

• Classification of followers:

I. According to the follower shape:

1. Knife-edge follower

2. Roller follower

3. Flat-faced (or mushroom) follower

4. Spherical-faced follower

II. According to the motion of the follower:

1. Reciprocating (or translating) follower

2. Oscillating (or rotating) follower

III. According to the path of motion of the follower:

1. Radial follower

2. Offset follower

• The various terms used in radial cams are presented under the section radial cam nomenclature'.

• The displacement diagram is one in which the abscissa represents the angular displacement of cam and the ordinate represents the corresponding displacement of the follower from its initial position.

• The most common follower motions, that are used in the design of cams, are:

1. Uniform velocity motion (or uniform motion)

2. Simple harmonic motion (SHM)

3. Uniform acceleration and retardation motion (or parabolic motion)

4. Cycloidal motion

• The cycloidal motion provides the best possible cam follower for high speed operations. Simple harmonic motion can be adopted for low speed operations.

• The cams with specified contours are used to avoid difficult in manufacturing and to reduce the cost of production.

• The two types of specified contours are:

1. Tangent cams, and

2. Circular arc cams.

• When the flanks of the cam are straight and tangential to the base circle and nose circle, then the cam is known as tangent cam.

• When the flanks of the cam connecting the base circle and the nose circle are of convex circular arcs, then the cam is known as circular arc cam.