A novel continuous indexing method for face-hobbed hypoid gear tooth grinding

Abstract

Grinding is an important finishing process for gear teeth to eliminate the surface deformation after heat treatment and improve accuracy. Grinding face-hobbed hypoid gears is especially challenging because the extended epicycloid curve of the generating gear does not match with the circular curve of the conventional disc-type bevel grinding wheel. In this paper, we propose a novel tooth grinding method based on continuous indexing, which uses a conical grinding tool to replace the blade on the face-hobbing cutter head. It includes two types of generating motions between the conical grinding tool and the generating gear, and between the generating gear with the workpiece. The mathematical model is developed to determine the geometric parameters of the conical grinding tool and to avoid interference between the conical grinding tool and non-grinding flanks. Finally, a numerical example is presented and a computer numerical control (CNC) virtual experiment is conducted to validate the proposed method. The results show that the tooth surface accuracy can be effectively maintained.