| 摘要 |
PROBLEM TO BE SOLVED: To easily form a fragile part of a wide width composed of three or more rows of hole row groups by piercing a workpiece with three or more rows of needle row groups.SOLUTION: The present invention relates to a formation method of a fragile part 4 for forming the fragile part 4 by a hole part 3 on the reverse surface side of a workpiece 1 by providing the hole part 3 by piercing a needle 2 into the workpiece 1 so as not to penetrate from the reverse surface side, and a needle row group 11 formed by juxtaposing the needle 2 in a plurality in a row shape, is juxtaposed by three or more rows, and the fragile part 4 composed of three or more rows of hole row groups 12 is formed by piercing the workpiece 1 with three or more rows of needle row groups 11 while imparting vibration between these three or more rows of needle row groups 11 and the workpiece 1.SELECTED DRAWING: Figure 2 |
