FORGING METHOD OF OUTSIDE JOINT MEMBER OF CONSTANT VELOCITY UNIVERSAL JOINT

PROBLEM TO BE SOLVED: To provide a forging method for reducing cost in a forging metal mold, attaining the long service life, and capable of molding a high accuracy track groove, for an outside joint member of constant velocity universal joint.SOLUTION: A forging method of an outside joint member is provided for squeezing-molding by pressing a cylindrical part in a die hole of a die, in a state of fitting an expandable-contractible punch set T to an inner peripheral surface of the cylindrical part of a front raw material of the outside joint member having a shaft part and the cylindrical part formed on one end of the shaft part, and the punch set T comprises at least a plurality of punches 20 and a punch base 21 for guiding a punch so as to be capable of advancing-retreating, and the respective punches are formed with a pair of molding surfaces 27A and 27B for molding an adjacent track groove.SELECTED DRAWING: Figure 15 【課題】等速自在継手の外側継手部材を、鍛造金型の低コスト化、長寿命化を図ると共に、高精度のトラック溝の成形を可能にする鍛造方法を提供する。【解決手段】外側継手部材の鍛造方法は、軸部と軸部の一端に形成された筒状部とを有する外側継手部材の前素材の筒状部の内周面に拡縮可能なパンチセットＴを嵌合させた状態で、筒状部をダイスのダイス孔に圧入してしごき成形するもので、パンチセットＴは、少なくとも複数のパンチ２０と、パンチを進退可能に案内するパンチベース２１を備え、各パンチには、隣り合うトラック溝を成形する一対の成形面２７Ａ、２７Ｂが形成されている。【選択図】図１５