Establishment of a Computer-Aided Design (CAD)/Computer-Aided Manufacturing (CAM) Process for the Production of Cold Forged Gears

Abstract

Abstract : In Phase II of the program, a spur gear and a helical gear were selected to be extruded, using dies which were manufactured using the techniques developed in Phase I. The computer program, GEARDI, was used to generate the corrected die geometry for each gear. kTHe dies were made both by electrical discharge machining. Extensive trials were conducted for both the spur gear and helical gear. Twenty spur and 20 helical gears were formed in a hydraulic press. Extra extrusions were made which were sectioned and inspected for grain flow patterns. Geometrical measurements made on the extruded gears show that errors in the tooth profile are small. The extruded spur gear, which is designed to be an AGMA qualilty Class 7 gear, was determined to be between quality Classes 7 and 8. The helical gear, a quality Class 7 gear design, was extruded to a Class 5 gear. For the spur gear, these results indicate a high degree of accuracy in the ability of the GEARDI computer program to compensate for elastic deflection and bulk shrinkage of the extrusion dies. The rather poor quality of the helical gears indicates that there are some technical problems which must be solved before this type of gear can be extruded successfully on a production basis. Keywords include: Computer aided design/manufacturing (CAD/CAM); Cold extrusion; Gear geometry; Die design; Extrusion trials; and Stress analysis.