METHOD FOR OPENING THROUGH-HOLE ON PERIPHERAL WALL OF WORKPIECE

摘要

PROBLEM TO BE SOLVED: To open a through-hole by punching with a press without generating burrs on the peripheral wall of a tube part. SOLUTION: The through-hole 70 is opened by forming a circular dent part 74 having an inner peripheral surface 75 by shearing which is slightly larger than the through-hole 70 in a diameter by press working in a predetermined position for opening the through-hole from the outside of the tube part 71 and driving a punch 53 which is smaller than the dent part in the diameter in the position corresponding to the dent part from the inside of the tube part. Because the inner peripheral surface of the dent part 74 is a shear plane and the shear plane is not pulled out to the outside by driving the punch, a fracture surface and the shear plane coincide in the inside of the through-hole. That is, the occurrence of burrs on the edge of the hole is prevented. COPYRIGHT: (C)2006,JPO&NCIPI