Effects of the hob cutter regrinding and setting on ZE-type worm gear manufacture

Abstract

A mathematical model for a ZE-type worm gear set is proposed. The characteristics of a ZE-type worm gear cut with an oversize hob cutter are investigated. Bearing contacts and kinematic errors in the ZE-type worm gear set due to regrinding of oversize hob cutters are also studied. Bearing contacts in the worm gear set were obtained using surface separation topology techniques and tooth contact analysis. It was found that bearing contact locations are sensitive to the hob cutter setting angle and setting distance. Kinematic error minimization was achieved modifying worm normal tooth angle. By applying the optimization theorem and computer simulation programs, optimum hob cutter settings and worm normal tooth angle were determined to improve bearing contact location and minimize the worm gear set kinematic errors. A numerical example is given to demonstrate the results of the investigation. The developed computer-aided manufacture program has successfully been applied to the worm gear manufacture and hob cutter design.