| 摘要 |
PURPOSE:To improve remarkably a yield of material by notching a material into the width of product while preventing a slug from separating from the material in notching both side edges of the material by a prescribed bridge width. CONSTITUTION:Both side edges of a material 11 of width L1 are notched successively by a prescribed width B each along the feeding direction of the material 11 to conform the width of the material to the width L2 of a product 13. Here, the extent of a shear droop in the direction of sheet thickness (t) produced by the notching of a punch 18 is gradually decreased in the direction reverse to the material feeding direction 12, and the depth of shear droop at the rear end is kept to be about 0.25t so that a notched slug 15 is prevented from separating from the material 11. Next, a product 13 having a prescribed shape is punched from the material having the width L2 under the condition that the feeding bridge width A is null. Thus a press punching where the bridge width (about 0.7t) is made far smaller than a conventional threshold limit value is performed, and a material yield (about 73%) is improved remarkably. |
