Method of forming grooves on metal pipe and groove-forming apparatus

摘要

Each of specific rollers which corresponds to one of the grooves is disposed in a circumference of the metal pipe at equal intervals and is pressed against the periphery of the metal pipe 10, thereby forming a plurality of the grooves at the same time. Because each of the grooves is formed by a specific forming roller, a plurality of the grooves can be formed separately, and the material of the wall between the grooves is prevented from being drawn. Thus, the grooves can be formed into a desired shape.