INDUCTION HARDENING OF SHAFT SCREW

摘要

PROBLEM TO BE SOLVED: To reduce the operating noise of a ball screw by reducing the irregular cooling with water for hardening, and reducing the variance in the contact angles of balls relative to a threaded surface of a shaft screw. SOLUTION: In a high-frequency hardening method of a shaft screw 8a to perform the induction hardening of the shaft screw 8a formed on a part of the shaft by moving the shaft 8 in its axial direction while rotating the shaft, the rolling direction of the shaft 8 is the direction in which a screw is advanced in the moving direction of the shaft 8, and the number of revolution of the shat 8 and the moving speed of the shaft are synchronized to satisfy the formula: (Number of revolution of shaft)=(moving speed of the shaft)/(pitch of the screw).