Generalized Modeling of Dynamic Cam-follower Pairs in Mechanisms

This paper deals with the application of homogeneous (4 × 4) transformations to the generalizing modeling of cam-follower pairs. The procedure adopted is generic, in that it suggests a method of incorporating the modeling of cam-follower pairs in a general purpose program, such as MAP (Mechanism Analysis Program, © General Electric Co.) capable of solving the dynamics of multibody systems, in which any of the bodies could be cams, or followers. This development covers both 2D and 3D cam-follower pairs: XY cams, rotary cams, and drum cams. The cams could be dynamic—with single, or two surfaces (or tracked), with the possibility of impacts between the follower and these surfaces, or, kinematic, with the follower being guided exactly in a slot. This generalized procedure allows one to model several cam-follower pairs in a multibody dynamic system. This is useful in studying, for instance, the dynamic effects that tend to bounce a follower off of a cam surface, the contact force generated, etc. The procedure, also, just as easily, allows for the easy studying of the effects of varying the cam surface profile. Several examples have been tried, and some correlations have been obtained with experimental observations.