| 摘要 |
PROBLEM TO BE SOLVED: To prevent burrs to be made in a hole of a base board and defectiveness due to a change in bore diameter to the minimum, to bore a hole with high accuracy, and to achieve higher productivity in boring work using a punching machine in a multi-layer base board or a flexible base board. SOLUTION: A first punch part 10 and a second punch part 20 are continuously formed in the axial direction in order from the leading end part, a first recessed part 1a is provided between the first punch part and the second punch part, a second recessed part 2a is provided in the rear part of the second punch part, the first punch part has a function of boring a workpiece, and the second punch part has a function of removing burr generated in the hole bored by the first punch part. COPYRIGHT: (C)2007,JPO&INPIT
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