Hypoid ring gear for differentials and method of producing the same

摘要

The invention is intended to reduce the installation cost and running cost, minimize the production cost and increase the tooth surface strength of hypoid teeth. To this end, a hypoid ring gear for differential is produced by the steps of upset-forging a round bar blank heated to a predetermined temperature to forma first disk-like intermediate article, die-forging said first intermediate article to form a second intermediate article in the form of a bottom-closed annular body which is smaller in inner and outer diameters and larger in axial thickness than the end product, punching out the bottom of said second intermediate article to form a third intermediate article in the form of a bottom-opened annular body which is smaller in inner and outer diameters and larger in axial thickness than the end product, shot-blasting said third intermediate article to remove the scale and reheating it to a predetermined temperature and ring-rolling it to form a fourth intermediate article in the form of a crude product which is somewhat smaller in inner and outer diameters and somewhat larger in axial thickness than the end product, orbitally forging said fourth intermediate article to forma fifth intermediate article having hypoid teeth formed therein by orbital forging, and normalizing and shot-blasting said fifth intermediate article to effect normalization and scale removal and then punching out the inner burr which is formed on said fifth intermediate article during tooth forming operation based on orbital forging and cold-coining it, thereby forming the end product.