Optimization of High Speed Geneva Mechanisms

Abstract

This paper presents an analytical and computer-aided procedure on the optimum design of Geneva mechanism. The subject is treated in two parts. In Part I, a set of parameters is derived for evaluating the performance and determining the dimensions of Geneva mechanism suitable for high-speed operation. The effects of geometry on dynamics, stress, as well as kinematics of the Geneva mechanism are investigated. Classical mechanics theory is used to derive explicit relationships between these performance parameters and the design parameters. Unlike conventional design, the dynamic load rather than the static load is used for the design for high speed. Computer-aided evaluations as well as the analytical results show that the dynamic load depends strongly on the geometrical parameters and is significant at high speeds and high inertial loading. It cannot, therefore, be overlooked. In general, the dynamic load imposes an upper bound on the determination of the width of a Geneva wheel. Based on the analysis presented in Part I, a unit computer program for the design of high-speed Geneva mechanism is described in Part II. The effects of the design parameters on Geneva performance are then investigated and design guidelines are presented. Using this procedure, the “computer-design model” is demonstrated, in examples, to be capable of running at higher speeds with a longer life than the models designed through conventional techniques.