A COMPARATIVE STUDY OF CAM MOTIONS FOR HIGH-SPEED SEMI-RIGID FOLLOWER CAM SYSTEMS

Abstract

A study is presented on the comparison of all the popular cam motions based on a refined dynamic model which takes into account the effects of cam profile errors and most of the important factors that influence the dynamic performance for a semi-rigid follower cam system. A stochastic model is developed to simulate the input signal resulting from the cam motion, including the deviations due to profile errors. The performance criteria comprise the vibrational response at the follower and the dynamic characteristics at the cam. It has been established that, at high speeds, it is not the vibrational behaviour, but the follower tendency to jump and the maximum contact force and cam torque values which determine the dynamic performance. The Modified-Sine, Simple Harmonic and 3-4-5 Polynomial motions have been shown to exhibit superior high speed performance compared to that of the popular Cycloidal and Modified Trapezoidal motions. Higher-order Polynomial motions give very poor performance at high speeds.