| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of unpunched parts by executing circular pattern punching of punching at equal pitches by a die in a circumferential direction with a radius around the center coordinates of a round hole as the center, and nibbling punching by a die along the whole periphery of a circle with a radius provided by a specific expression around the coordinates, in regular order. SOLUTION: The center coordinates (x, y) of a round hole on a workpiece W are positioned between dies. and a hole Ch is punched at a single stroke in the center of a round hole HL by the die with a diameter P. The workpiece W is moved in the radial direction of the round hole HL to perform circular pattern punching, and the center distance of the adjacent small holes Sh is made at least P/2. On the circumference of a radius RN around the coordinates (x, y) as the center, the hn (=2×2N) number of circular pattern punching are repeated at equal pitches in the circumferential direction up to the Nth round. Nibbling punching is further performed on the circumference Cn of a specific radius R-(P/2) around the coordinates (x, y) by the die with the diameter P. The number of punching is thereby reduced to punch a large bore round hole.
|
