Patent ID: 6161415
Filing Date: 2000-12-19
Classification: B21J

Abstract:
A cold deep hole forming device comprising:a supporting base for supporting a member to be formed;a punch for forming a deep hole in the member to be formed;a clamp holder provided outside of an outer circumference of said punch, said clamp holder having an inner circumferential sloped face and including an operating fluid reservoir and a piston disposed in said operating fluid reservoir of said clamp holder; anda clamp comprising a plurality of split clamping pieces disposed in said clamp holder, said clamping pieces having an outer sloped face for contact with said inner circumferential sloped face of said clamp holder and said clamping pieces being provided with a slope corresponding to the slope of said inner circumferential sloped face of said clamp holder, such that when a deep hole is formed in the member with said punch, fluid pressure in said operating fluid reservoir causes said piston to centrally move said clamping pieces along said inner circumferential sloped face in order to constrain the member to be formed at an outer circumference of the member.