A Study of the Crowning Method for the Type 3 Worm Gear : An Analysis of a Calculation Method for the Profile of the Relieving Tool

Abstract

A precise analysis has been made on the profile of the relieving tool of the type 3 worm hob. Firstly, the type 3 worm thread surface, which is normal to the basic thread surface of the hob, is chosen as the helical cutting face of the type 3 worm hob. Secondly, the calculation method for the profile of the relieving tool for this worm hob is obtained. Thirdly, the calculation method for the deviation from the tangent at the pitch point on the profile of the relieving tool is clarified. Then, the experimental manufacture of a relieving tool is performed by applying these calculation methods to a numerical example of the type 3 worm hob. The theories in this analysis are verified by practical relief cutting of the type 3 worm hob with the relieving tool. The necessity and the effectiveness of these calculation methods are confirmed.