The start gear shaft is the key part of automobile starter

it is involutes small module internal gear with addendum modification;tooth surface of the internal gear is complex shape of five pleats.It is step shaft with H/D>6 in the outline.The shaft can’t be machined and plastic forming also is difficult.Meeting the needs of markets and improving comprehensive function of automobiles

the high efficiency precision forming technology method of single-step chinless-forming for internal gear tooth surface and external gear tooth is put forward based on analysis

study and repeated test.In the same time

a set of high accuracy die with simple novel structure and long service life is designed and manufactured.The advantages of the method have been verified that utilization ratio of material and production efficiency is high.For this reason

the method is profitable reference for producing the same type of complex shape gear.