| 摘要 |
PURPOSE:To obtain a metallic sheet for pressing having a wide range of forming margins by forming rugged structures of specific sizes on the surface of the metallic sheet. CONSTITUTION:Two kinds of large and small recessed parts which vary in sizes are formed on the surface of the metallic sheet. The outside diameter of the small recessed part is specified to 10 to 90mum, the outside diameter of the large recessed part to 100 to 280mum, the area rate of the recessed part to >=20%, and the depth of the recessed part to <=10mum. The small recessed part constituted on the projecting parts in a low-pressure surface area exhibits the active lubricating effect and the effect of the recessed part is lost as the area shifts toward the high surface pressure area. The large recessed part in turn contributes to the lubricating state to make up the easy of flow of the steel sheet. The probability that the defective forming occurs is, therefore, lowered and the yield of the product is improved. |
