PURPOSE: To produce the press formed part excellent in the dimensional accuracy by forming either a punch metal die or die metal die or the both with heating at the specified temp. in the forming of a thin steel plate.

CONSTITUTION: A spring back is reduced in case of forming a high strength thin steel plate by increasing the temp. of either a punch metal die or die metal die or the both in pressing. In order to obtain this effect the punch metal die and die metal die are heated 100°W400°. By this heating the steel plate to be formed is softened and the conformability with the metal die is increased as well. On the other hand 400°C is taken as the upper limit because of an extremely thin oxidized film being formed and the external appearance being remarkably spoiled on the steel plate heated upto high temp. while under cooling in the atmosphere as well as hardening the steel plate to be formed with heating of the metal die to high temp. too much. This method is effective for applying to a mild steel plate as well besides high strength thin steel plate.