METHOD FOR MANUFACTURING COUPLING SHAFT WITH COLLAR

Japanese Patent JP3787767

B2

PROBLEM TO BE SOLVED: To provide a method for manufacturing a coupling shaft with a collar which can continuously manufacture the shaft integrally by multistage cold- forging and which has an accurate spline. SOLUTION: The method for manufacturing the coupling shaft with the collar comprises the steps of forcing a first material A obtained by cutting a wire material in a predetermined length and performing a Bonderite treatment, into a die from one direction, and forming a second material B having a head A2 at one end and having a shaft A1 smaller in diameter than that of the first material A at the other end, then forcing a center pin to the head B2 of the second material B, cold-forging the head B2 to form a third material C having a head C2 with a collar C3 having a preliminary recess C4, further forcing a molding pin to the head C2 of the third material C, forming a fourth material D having a head D2 with a collar D3 having a large diameter with a shaft hole D4, and finally hitting the fourth material D to the die side by a punch, simultaneously forming splines 15, 16 on the inner surface of the shaft hole D4 of the head D2 and the outer surface of the distal end of the shaft D1 of the fourth material D to form the final molding.