| 摘要 |
PURPOSE:To enlarge a shape of the end part of a blank material gradually from the tip of the material to make a biting of roll easy, by slanting cut edges at the front and rear ends of the material from the line intersecting the direction of material fed perpendicularly. CONSTITUTION:Cut edges 6 and 6' of the end parts, being the front and rear ends of a blank material 1 in the direction of feeding, are formed by slanting them from the line intersecting the feeding direction of the material 1 perpendicularly. The material 1, having the formed cut edges at its both end parts, is inserted to a coiler rolls to be processed by roll bending. Then, the material is bent easily and is bitten surely at the time of roll biting because the section modulus of the material, in the direction of the coiling axis of the end part having slanted cut edge, becomes gradually larger from the front tip of the material. Further, when the rear end part of the material 1 is bitten by the rolls after roceeding the roll bending work, the material is formed into a cylindrical shape easily and the roundness is kept well while decreasing a spring back, because the section modulus of the rear end part decreases as the part approaches the rear end tip. |
