Formation of thin ring gear with high accuracy by hot form-rolling and warm finish form-rolling

摘要

The warm finish form-rolling process was introduced after the hot form-rolling to form a thin ring helical gear with high accuracy of JIS Class No.4. Accuracies of tooth profile, lead, single pitch error and pitch error between adjacent teeth of the hot form rolled gear were improved by two to three grades of accuracy with the finish form-rolling. High stiffness of the rolling machine, suitability of the dies indentation in the sizing operation in the hot form-rolling and a restraining of thermal distortion after warm finish rolling were effective for improving the gear accuracies of tooth space runout and the accumulated pitch error. The ring helical gears with accuracy of JIS Class No. 3 to 4 were formed by combining hot form-rolling and warm finish form-rolling under controlled blank size, heating conditions, lubrication conditions and die temperature.