Computer Aided Design And Optimization of Worm Gear Sets

Abstract

The present work is to create a computer Aided Design (CAD) package for the design optimization of cylindrical worm gear sets. The design program estimates the gear set geometrical variables and strength variables as the bending, wear and deflection safety factors. Strength calculations are based on the American Gear Manufacturers Association (AGMA) standard, namely ANSI/AGMA standard 6022-C93 and empirical relations. The designer can change the design variables to satisfy any constraints applied. The program gives all geometrical data and loading conditions. The optimization procedure manipulates the computer aided design program in an iterative way. The procedure changes the design variables such that the objective function subject to specified constraints is minimized. The objective function in this work chose to minimize the volume of worm gear sets and to maximize their efficiency. The main constraint is to insure that the bending stress is lower than or dI equal to the allowable bending stress and to insure that the tangential gear force is lower than or equal to the critical capacity. This would further make best utilization and selection of material. This would also indirectly minimize the volume and maximize the efficiency. The effect of the design variables, the input parameters and the type of material on the objective function is presented. The results indicates that the optimization procedure has reduced the volume of wormgear set from 25% to 40% of their original volume and maximized their efficiency about 0.5% to 1.5% for low reduction ratio and from 25% to 40% of their original volume and maximized their efficiency about 5% for high reduction ratio compared with case study.