MANUFACTURING METHOD OF SUB-FRAME

摘要

PURPOSE: A sub frame manufacturing method is provided to reinforce the intensity of a structurally weak part by locally performing the structurally weak part of a sub frame with induction heating without putting a reinforcing member by welding. CONSTITUTION: A sub frame manufacturing method comprises a press molding step(S110), a welding step(S120), an induction heating process step(S130), and a cooling step(S140). The press molding step molds hardened steel with a press and comprises a front, a rear, a right, and a left member. The welding step forms a sub frame main body by welding the first and the rear member and the right and the left member. The induction heating process step selectively performs an induction heating process on the surfaces of the right and the left member including structurally weak intensity. The cooling step cools the heat processed sub frame main body. [Reference numerals] (AA) Start; (BB) End; (S110) Press molding; (S120) Welding; (S130) Induction heating process; (S140) Cooling;