On the Ranges of Design Parameters to Avoid Intersecting of Rib Surfaces of Roller Gear Cam Mechanisms

Abstract

To investigate the surface characteristics of cam mechanisms is one of the most important tasks of designing them. There are many studies concerned themselves on undercutting problems. For some cam mechanisms whose cam has ribs, such as roller gear cam mechanisms (RGCMs), the allowable ranges of some design parameters to avoid intersecting of rib surfaces are smaller than those to avoid undercutting. However, no study on the intersecting problem can be found. The main purpose of this study is to propose the methodology for the determination of the ranges of the design parameters of RGCMs, to avoid the problem of rib-surface intersecting.Homogeneous matrix transformation and theory of conjugate surfaces are applied to derive the equation of meshing of RGCMs with conical meshing elements. Then, a model to describe the rib surfaces of the cam just contact to each other is built. Based on them, the methodology to determine the range of each design parameter to avoid intersecting of rib-surface is proposed. A RGCM used as the automatic tool changer within machining centers is adopted as the example. In the example, not only the ranges for avoiding intersecting but those for avoiding undercutting are also given, and their intersections are the feasible ranges of the design parameters.