PURPOSE: To decrease uniformly the sectional area of a long columnar body by supporting said body with supporting devices adjacent to an eccentric ring roll, pressing the caliber surface of the eccentric ring roll to the surface of the long columnar body and moving the calibers in the direction intersecting the long columnar body so that the part deformed plastically by pressing is advanced while it is moved circumferentially.
CONSTITUTION: A pipe 7 inserted therein with a mandrel 6 is penetrated into an eccentric ring roll 4 by pushing forward the end part of the mandrel with a propelling device 14. The pipe 7 is supported with the caliber D1, D3 surfaces of supporting ring rolls 3, 4 and the pipe 7 is pushed into the working surface of the caliber D2 of the roll 4. When a gear 9 is supported in a housing 11 and is rotated, the inside surface 13 of a gear having the center different from the center of said gear rotates eccentrically and the roll 4 and the caliber D2 which are supported on the surface rotate eccentrically, thereby decreasing the wall thickness of the pipe 7 by pressure. The pressure decrease of the pipe 7 arises in the supporting ring roll part as well and the plastically deformed part rotates in the same direction at the angle different roughly by 180° from the plastically deformed part in the eccentric ring roll part, by which the wall thickness is decreased. This method is applicable in rolling of a bar as well, in the same way as for the pipe.
KAWANAMI TAKAO
JP38005957A |