HOLE PIERCING METHOD, METHOD FOR MANUFACTURING STRUCTURE WITH HOLE, AND STRUCTURE WITH HOLE

摘要

PROBLEM TO BE SOLVED: To provide: a hole piercing method that facilitates hole piercing using a hot press; a method for manufacturing a structure with a hole; and the structure with the hole.SOLUTION: A hot press forming method includes: a heating step S1 of heating a workpiece W; a cutting/machining step S4 of piercing a hole through the workpiece W using a piercing blade 24a; a recess machining step S5 of forming a recess C for enlarging a diameter of the hole H around the hole H opened in the cutting/machining step S4; and a cooling step S6 of cooling the workpiece W. In the method, an enlarged amount of the diameter of the hole H by the recess C formed in the recess machining step S5 is larger than a reduced amount of the diameter caused in the cooling step S6.