Conventionally, forming of outer panel components of an automobile and the like have been carried out by press forming, in which a work is press processed using a press die. Generally, it is preferred that a press die used in a press process be such that the die surface, which is a contact surface with a work in the press die, be smoothed. By smoothing the die surface, it is possible to increase surface precision of a work (outer panel components) formed.
As a method for smoothing a die surface, the applicant proposes a processing method of a die surface and a die for which the processing method has been applied (see Patent Document 1) in which, first, a forming surface of a die is formed by a cutting process, then a synthetic resin is applied to the formed die surface, and next shot blasting is performed for smoothing a shape of the die surface. According to a method described in Patent Document 1, by a cutting process, it is possible effectively to grind high spots that are leftover from cutting generated on a die surface, thereby efficiently carrying out smoothing of a die surface.
Patent Document 1: Japanese Examined Patent Application Publication No. Hei 8-263