To provide a small diameter drawing method by which the damage to a punch by buckling and lateral pressure is prevented in the case of forming a blind cylinder having the small diameter and depth of not less than a certain value.
This method comprises a primary drawing stage where a metallic flat sheet is pressed along die holes with a punch and a secondary drawing stage where press is performed along the die holes with a plate surface and furthermore a first drawing stage has drawing for successively reducing the the diameters of the punches and the diameters of the die holes at least one time and a second drawing stage has drawing for successively reducing the diameters of the die holes at least one time, and the damage of the punch by buckling and lateral pressure is prevented by this small-diameter drawing method.
SENOO TOMIO
NEGORO HIDEAKI
Tomoyasu Sakaguchi
Hiroki Naito