Assembly of metal flange and resin pipe and method of manufacturing assembly

A method of manufacturing an assembly of a metal flange and a resin pipe in which the metal flange is externally fitted to and integrated with the resin pipe, the method comprising:

• forming unevenness on a surface of an insertion hole of the metal flange into which the resin pipe is inserted;
• disposing the metal flange in an insert portion provided in a cavity body of a mold for forming the resin pipe;
• forming a rib forming cavity on at least one side of both ends of the insert portion in an extension direction of the cavity body, the rib forming cavity being connected to the insert portion, having a diameter larger than an outer diameter of the cavity body, and being continuous over an entire circumference of an outer circumferential surface of the cavity body in a circumferential direction;
• injecting molten resin into the cavity body and the rib forming cavity in a state where the mold is clamped to form the resin pipe by curing the molten resin;
• fitting the metal flange into a fixing groove continuous over the entire circumference of the outer circumferential surface of the resin pipe in the circumferential direction;
• causing an outer circumferential surface of the fixing groove to enter the unevenness on the surface of the insertion hole;
• and
• forming a circumferential rib on at least one side of both ends of the metal flange in a longitudinal direction of the resin pipe, the circumferential rib abutting on an end surface of the metal flange, having a diameter larger than an outer diameter of the resin pipe, and being continuous over the entire circumference of the outer circumferential surface of the resin pipe in the circumferential direction.