A Study on High Reduction Face Gears : 2nd Report, Cutting of Face Gear(Machine Elements, Design and Manufacturing)

This paper describes a hobbing method for a face gear meshing with a large helix pinion with a small number of teeth. Due to small numbers of hob teeth and cutting edges, it is known that interference on hob tooth flanks is apt to occur, and also profile errors are produced. In this paper, to avoid this interference a new hobbing method is proposed. In the method, cutting is carried out in a cycle which consists of four steps during one rotation of the hob. (1) The hob is fed to the gear blank, (2) rotated for gear cutting, (3) kept away from the blank, (4) returned to the initial position and a little rotation of the blank is given for the next cycle. The face gear is finished by repeating the cycle until the gear blank makes one rotation. To realize the proposed method, an NC gear-cutting machine with four control axes is designed and made. Meshing tests using the face gears finished on the gear cutting machine are conducted. As the results, smoothly meshing and good contact patterns are obtained.