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:
The general shape of the cam is generated by the interaction of the cam and follower motions.
|•||Planar: the cam is disc, plate, flat|
|•||Spatial: the cam is cylindrical, barrel, globoidal|
|•||Planar: the cam is a slot, linear curve or ramp|
|•||Spatial: the cam is a slider-cylindrical, barrel|
The modes of cam motion are.
|•||The cam swings back and forth; the cam 'oscillates'|
|•||The cam rotates continuously|
|•||The slide back and forth; the cam 'reciprocates'|
|•||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'.|
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'|
|•||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.|
The shape of the cam-follower influences the shape of the cam. There are advantages of each shape.
|•||Barrel [also called a Crowned Roller], Logarithmic|
|•||Knife-edged - not a practical cam-follower, but included here for completeness|
See Cam-Follower Shapes
The constraint between the cam and the follower influences whether the cam is 'open' or '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.
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'.