| 摘要 |
PROBLEM TO BE SOLVED: To provide a punch unit producing method capable of forming a fine through hole to a metal plate material to be machined, while improving durability.SOLUTION: A punch unit is produced by: a tapering part forming step of forming a rectangular cross-sectional tapering part 65' for a punch part, by making a plurality of incisions from a side of a metallic block material and forming a plurality of comb teeth portions serving as the punch part, and also by gradually tapering each comb teeth portion toward a tip end; and a curved surface forming step of forming a curved surface such that a dihedral angle with side surfaces intersecting to each other is rounded, by blasting a polishing liquid containing abrasives and water, from a nozzle 83 of a blast head 82 to at least the tip end side of each comb teeth portion, after the tapering part forming step. |
