PURPOSE: To punch the vent hole formed by a small cleat part surrounded by a big cleat on a planar blank material by using the upper die having the plural outer edge punching male blade equipped with a blade height adjusting mechanism and the plural inner side punching male blade of a fixed blade height and the lower die of the female blade corresponding to the male blade.
CONSTITUTION: The pitch between a male blade 5 and female blade 7 is combined to an upper die 3 at equal intervals according to the distance determined by the small cleat width and large cleat width and the number of punching vent holes. In the case of not piercing the vent hole 2 of the outer edge part a slide 10 is pulled in by actuating a blade height adjusting cylinder 9 to lower the blade height of the male blade 5. In the case of punching the vent hole 2 on a work 1 the blade height is increased by inserting the slide 10 reversely to make a hole. The female blade 7 is buried in the lower die corresponding to the male blades 5, 6. The inner side punching male blade 6 is the male blade of the case of the vent hole 2 being pierced all on each index of the work 1 and its blade height is higher at all times. The vent hole 2 is then pierced by moving the work 1 by the distance adding the length of one side of the vent hole 2 to small cleat width. Also the vent hole 2 composed by the small cleat 18 surrounded by the large cleat 1 is pierced by moving the same distance.
OCHIAI IZUMI
ASAHINO YOSHIO
