The rotary forging die of bevel gear is composed of concave mold cavity and upper mold swing head. The machining accuracy of concave mold cavity is the key to ensure the precision forming of bevel gear. The cavity of the die is obtained by EDM, so the tooth shape design of the tool electrode will play an important role in the machining accuracy of the cavity.
In the cold rotary forging process, there are basically no problems such as oxidation and cold shrinkage of forgings and thermal expansion of forging die during hot forging. Therefore, it is considered that the tooth profile size of bevel gear forgings is the same as that of female die. Therefore, the influence of discharge gap during electrode machining and electrode burning loss on the tooth profile accuracy of electrode should be mainly considered when designing the tooth profile of tool electrode. Therefore, the existence of discharge gap and electrode burning loss are two main factors that should be considered in the tooth shape design of tool electrode.
When designing the tooth size of tool electrode, based on the tooth size of part gear and considering the influence of discharge gap, the burned electrode gear can be obtained; The tooth profile of the final electrode gear can be obtained by counting the burning loss of the electrode. This is the geometric dimension accuracy transfer relationship between bevel gear part, concave model cavity and electrode.