| 摘要 |
PURPOSE:To form a circular ring without causing buckling by applying axial compressive force to a material ring, thrusting an outer roll that can move independently in radial direction divided to plural number against outer periphery of the material ring, and forming a concavity while rotating the material ring. CONSTITUTION:A material ring 21 is pressure held between inner rolls 30, 31 and expanded, and the ring is rotated while applying large compressive force to the upper part of the ring 21 by tilting the inner rolls 30, 31 by the action of cylinders 35, 36. Pressed position of the ring 21 is changed to circumferential direction by a cylinder 39. An outer roll 10 is pressed down and both end parts of the ring are pressed by flange part forming rolls 12, 13. Then, an eccentric shaft 14 is rotated by the action of a cylinder 29, and a drop part forming roll 11 is pressed down relatively against flange part forming rolls 12, 13. At this time, the drop part forming roll of inner rolls 30, 31 keeps the gap to the drop part forming roll 11 of outer roll 10 automatically in the thickness of the material ring by deformation of an elastic member 42. Thus, no reduction of thickness of the material ring 21 is caused. |
