| 摘要 |
PURPOSE:To prevent the slip of a material to be worked with respect to a flat die at the initial stage of rolling by forming a flat part in the starting part of biting of the flat die and making the distance between the opposite flat parts of a pair of flat dies smaller than the diameter of the material. CONSTITUTION:In the biting starting-part 10a of a biting part A of flat die 10, a flat part 11 extending in the longitudinal direction of flat die 10 is formed at the side of inserting a material 1 to be worked, and edge-chamfered faces 12 and grooves 14 are formed at both sides of the part 11 to reduce the inserting resistance of material 1. Further, the roughness of the upper flat surface of flat part 11 is previously roughened. In rolling the material 1 by using a pair of the flat dies 10, the distance (l) between the flat parts 11 is previously made smaller than the diameter D of the peripheral surface of a working part of material 1 by a prescribed dimension. Then the slip of material 1 with respect to the flat die 10 at the initial stage of rolling is effectively prevented, and high working accuracy is obtained. |
