METHOD FOR MANUFACTURING BRANCHED PIPE AND BRANCHED PIPE MANUFACTURING DEVICE

摘要

A method of manufacturing a branched pipe includes: a first swelling step of swelling a swelled part from a main body of a pipe blank by pressurizing the inner surface of the pipe blank by an elastic body, and simultaneously, forming an opening in the tip portion of the swelled part along a circumferential direction; and a second swelling step of swelling the swelled part from the main body by pressurizing the inner surface of the pipe blank by the elastic body.