| 摘要 |
<p>PURPOSE:To prevent wrinkles and stretch cracks generated by stretching, contraction or imbalance of stretching and contraction in performing bending in the direction of width and folding back bending in the longitudinal direction at the same place by forming a bulged part at that place beforehand. CONSTITUTION:In forming a product 1 by drawing, the material plate 25 on the lower blank holder 15 is grasped by wrinkle pressing faces 16, 18 by lowering of a die 12. Then, it strikes against a punch 11 by lowering of the holder 15 and is bent. At that time, the plate 25 is pushed up partially by a subpunch 20 which is pushed up by a spring 22, and a bulged part 26 is formed. The position covers the slant face 4 to the flat face 5 and corresponds finally to the position where bending in the longitudinal direction and transverse direction is performed. The position is a position where contact with the punch 11 takes place latest. With further lowering of the die 12, drawing makes progress and the ridigity of the plate 25 increases. The punch 20 is pushed down, and goes into the punch 11. Finally, the bulged part 26 is stretched and stretching and contraction occur in proper quantities. Consequently, wrinkles and stretch cracks do not take place and a product of required shape can be obtained.</p> |
