19-12-2012, 03:16 PM
CAM MECHANISMS
CAM MECHANISMS.ppt (Size: 5.72 MB / Downloads: 89)
Definition
A cam may be defined as a machine element having a curved outline or a curved groove, which, by its oscillation, rotation or reciprocating motion, gives a predetermined specified motion to another element called the follower .
It is usually consists of a cam (the driver), the follower (the driven element), and the frame (the support for the cam and the follower).
LEONARDO DA VINCI
The first cam designs were found in Leonardo da Vinci’s sketches in his Codex Madrid I.
Leonardo found cam mechanisms being very compact mechanical devices to transform rotary motion to linear motion.
Classification of Cams
Cams are classified in three ways:
In terms of their shape, such as wedge, radial, cylindrical, globoidal, conical, spherical, or three-dimensional;
In terms of the follower motion, such as dwell-rise-dwell (DRD), dwell-rise-return-dwell (DRRD), or rise-return-rise (RRR); or
In terms of the follower constraint, which is accomplished by either positive drive or spring load as mentioned previously.
Flat Face Follower
This has the advantage that the only side thrust present is that due to the friction between the follower and the cam. (Fig.)