| 摘要 |
PROBLEM TO BE SOLVED: To press and crush the whole inner surface of a welded pipe including an inner surface welding bead, manufacture the welded pipe smoothing the inner surface with reduction in cost. SOLUTION: A metal band is molded continuously into a cylindrical shape, plate width direction both end parts are welded together, in the case of manufacturing a welded pipe 4, in a position where an inner surface welding bead 5 is placed in a high temperature condition of 200 deg. or more, the inner surface welding bead 5 is crushed by a pair of press rollers 10 in contact with the inner surface welding bead 5 and a base material part inner surface on the opposite side to the inner surface welding bead 5 and backup rollers 40 interposing the welded pipe 4 to confront the press rollers 10, and successively the whole inner surface of the welding pipe is crushed by an inner metal mold 20 in contact with the whole inner surface of the welding pipe 4 and an outer metal mold 50 in contact with an outer surface of the welding pipe 4. In this way, a burden of the metal mold is reduced, as a substitute for a seamless pipe, a pipe material usable for a cylinder or the like is manufactured by reducing a cost. |
