| 摘要 |
PURPOSE:To improve the yield of material, and to improve the productivity, by composing the rolling rolls with two large diameter rolling rolls and a small diameter rolling roll, and by causing said small diameter rolling roll to make the rolling contact with a backup roll. CONSTITUTION:A bar type material 10 is supported freely rotatably around its axis 10a and movable in its axial direction. A couple of large diameter rolling rolls 11, 12 and a small diameter rolling roll 13 are arranged around the outer surface of the material 10 taking some distance between mutual outer surfaces; hereupon, the rolling rolls 11, 12, 13 are respectively supported freely rotatably around their own axes 11a, 12a, 13a all parallel to the axis 10a of the material 10, and besides, freely touchably and detachably from the material 10. The outer surface of rolling rolls 11, 12, 13 is respectively provided with conical surfaces 11b, 12b, 13b in which each large diameter side is placed on the front side in the advancing direction of the material 10 and is pressed to the outer surface of the material 10. A large diameter backup roll 14 is provided for supporting said small diameter rolling roll 13 by making the rolling contact with the rolling roll 13. The rolling rolls 11, 12 and the backup roll 14 are driven to rotate in the arrowed directions and are shifted so as to separate from each other relating to the extent of the axial movement of the material 10; hereby, the desired taper part is formed in the material 10. |
