Abstract
Cam mechanisms have many applications in automatic machinery. Considerations of dynamic performance require the profile shape to be defined indirectly from the follower motion, the flexibility of timing and configuration introducing additional variables. Consequently the design and manufacture of new master cams using conventional techniques is laborious and expensive. Precision is essential since the follower motion is sensitive to minor dimensional inaccuracies and discontinuities of curvature. The object of this investigation is to simplify both the design and manufacture of a new master cam. The author's survey of previous work showed it necessary to establish the design sequence before the processes involving greatest effort could be isolated. His associated study of existing profile copying and generating devices found none which satisfied the criterion of extensive application, but identified weaknesses of previous designs. This thesis considers the adaption of the copying principle to manufacture cam profiles from the intrinsic shape of a leaf spring deflected to suit specified boundary conditions, so eliminating dependence upon co-ordinate data, complex transmissions and special templates whilst relying upon the repeatability of an instrument in preference to the positioning accuracy of a machine-tool. Profiles for two distinct follower motions can be derived by this means, their characteristics resembling those of SHM and cycloidal motion respectively. The characteristics are functions of the displacement equation. A search revealed no comparison nor experimental verification of previously published analyses of the elastica. Limitations of the previous analyses led the author to derive new solutions using the method of perturbations; these have the advantage of simple computation and give a direct solution for any intermediate position. Experimental studies showed good co-relation between theoretical and measured deflections. The attachments were designed and manufactured and profiles cut using this process.