A general framework for geometry design of indexing cam mechanism

Indexing cam mechanism is one of most important mechanisms in automated machineries. This paper presents a general frame for kinematic analysis and geometry design of indexing cam mechanism, such as parallel cam mechanism and roller gear cam mechanism. This method applied screw theory to describe structure of cam mechanism and developed the kinematic equations by using Product of Exponentials Formula (PEF). As long as such structure parameters are given as position and orientation of central line in turret, cam and rollers, geometry modeling of indexing cam can be implemented in a general frame of kinematic equations by applying this method. The paper gives examples to obtain the geometry models of roller gear cam, barrel indexing cam and parallel indexing cam. Our work suggests that this method can avoid the burdensome work on building coordinate systems, transformation matrix and understanding on the mechanism. Moreover, this method can be used to innovate and design new types of indexing mechanism.