Classification of Cam and Cam-Followers

There is not a general classification for cam mechanical systems. However, the 'functional embodiments' and 'functions' of each sub-system have relatively few possibilities, which we can classify.

A General Classification of Cam and Cam-Follower Types:

tog_minus        Cam : General Shape

The general shape of the cam is generated by the interaction of the cam and follower motions.

Rotating Cams:

Planar: the cam is disc, plate, flat
Spatial: the cam is cylindrical, barrel, globoidal

Translating Cams:

Planar: the cam is a slot, linear curve or ramp
Spatial: the cam is a slider-cylindrical, barrel

tog_minus        Cam : General Motion

The modes of cam motion are.

Rotating Cams:

The cam swings back and forth; the cam 'oscillates'
The cam rotates continuously

Translating Cams:

The slide back and forth; the cam 'reciprocates'

Stationary Cams:

The cam is a plate that is nominally 'Circular', fixed to a frame [most common on rotating machinery - such as bottle labelling, capping and filling machines].
The cam is a ramp that is nominally 'Linear', for example it is a 'slot' or 'ramp'.

tog_minus        Cam-Follower : General Motion

The modes of cam-follower motion are:

Rotating Followers: a 'lever'

Swing 'back and forth', the lever 'oscillates'
Progressive motion, they index, in one direction

Translating Followers: a 'slider':

Sliding 'back and forth' , the slider 'reciprocates'

Stationary Followers:

The Stationary Cam-Follower moves the Cam, not as common, molding machines, wedge
A stationary follower might be used to position a cam part, like a 'wedge' cam.

tog_minus        Cam-Follower : General Shape

The shape of the cam-follower influences the shape of the cam.  There are advantages of each shape.

Cylindrical Roller
Taper Roller
Barrel [also called a Crowned Roller], Logarithmic
Knife-edged - not a practical cam-follower, but included here for completeness
Flat-faced

See Cam-Follower Shapes

tog_minus        Constraint between Cam and Follower

The constraint between the cam and the follower influences whether the cam is 'open' or 'closed'.

Force Closed

The constraint between cam-follower and the cam is with:

Gravity, Spring, Air-Cylinder, ...

When the track is 'Force Closed', the follower has one contact point/line with the cam.

Form Closed [also called Body Closed Cams]

The constraint between the cam-follower and the cam is with a:

Groove (Track), Rib, Slot, within which the cam-follower is held.
Conjugate Cams: these systems require manufacturing and production accuracy.

When the track is 'Form Closed', the follower can have two contact points/lines with the two cams.

tog_minus        Type of Motion

Non-progressive:

The follower returns to the same position after each cycle by reversing its direction of motion at some point in the cycle.

Progressive: [also called 'indexing', see also Indexing Cams) ]

The follower moves progressively to a new position at the end of each cycle.

 

In most cases the follower is replaced by another follower at the end of a motion cycle. Equally spaced followers return to their original positions after a number of motion-cycle. Most indexing systems use several roller followers equally spaced around a follower wheel or 'turret'.

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