| 摘要 |
PROBLEM TO BE SOLVED: To perform eccentric spinning while preventing increase of a processing time caused by a processing amount limitation per one path to improve production efficiency and while inhibiting occurrence of wrinkle or a crack at a pipe end without preparing a mandrel.SOLUTION: When forming a diameter-reduced portion at a pipe end of a pipe to be processed by using the pipe to be processed and processing rollers which are arranged on an outer periphery of the pipe to be processed and revolve relatively around the same and by axially reciprocating the processing rollers while moving the same in a radial direction of the pipe to be processed, representing a curvature radius of an end of the used processing roller as r, the processing rollers are reciprocated while being turned back at a position which is within r in an axial direction from the pipe end to form a flare-shaped projection at the pipe end of the pipe to be processed. |
