PROBLEM TO BE SOLVED: To provide a mandrel 1 for planishing which can easily hold a thin sheet cylinder formed by welding in a prescribed position by being inserted into the cylinder, and enables accurate planishing of a weld zone while preventing mispositioning.;SOLUTION: Plane parts 3 of a prescribed width are longitudinally formed in a circumferential direction on the surface of the mandrel 1 and support parts 2, 2 are formed with both ends in the circumferential direction of the plane parts as angles. Both the support parts 2, 2 abut on the inner peripheral surface of the inserted cylinder to stably support the cylinder 5 in the prescribed position and to facilitate positioning of the weld zone 6. The weld zone 6 is held between the mandrel 1 and a pressure roller 4 and is supported in this state without mispositioning even if the pressure roller 4 is rolled on the weld zone 6 and thus the planishing is performed.;COPYRIGHT: (C)2006,JPO&NCIPI
展开▼