Spin-forming method and spin-forming apparatus

摘要

While a material pipe 1 and a roller 10 are revolved relative to each other with a predetermined radius, the material pipe 1 and the roller 10 are moved relative to each other in the direction of progress of forming by eccentrically moving the center axis C1 of the material pipe 1 and the revolution axis CK of the roller 10 relative to each other and simultaneously moving the material pipe 1 and the roller 10 relative to each other in the directions of the axis. During movement in the direction of progress of the forming, an end portion of the material pipe 1 is deflected by controlling the axis-direction moving portion so that the roller 10 is moved relative to the material pipe 1 in the direction of the axis when the circumferential position of the roller 10, with respect to a circumference of the material pipe 1, changes from an inner side of the direction of deflection toward an outer side of the direction of deflection. This allows the movement of the roller 10 relative to the material pipe 1 in the direction of the axis to be stopped when the circumferential position of the roller 10 changes from the outer side of the direction of deflection toward the inner side of the direction of deflection. <IMAGE>