A Study on Hob for Hourglass Worm Wheel. 3rd Report. Hob Design for Hourglass Worm Wheel with Crowned Teeth.

Abstract

A new concept of a new type hob for hourglass worm wheel has been proposed. The hob can be used repeatedly when the cutting edges become worn. In this paper, the authors try to design the hob generating the crowned wheel tooth surface. In this purpose, the tooth profile data are modified to be desirable crowned form using the B-spline curve fitting method. The concept was applied to the design of a hob for wheel tooth generation of the hourglass worm gear generated by a tool with a conical surface. Numerical calculations show that both the crowned form and the amount of crowning are exactly controlled using the hob.