Even pressure welding method by using fluid pressure

摘要

A plurality of joined members each made of thermoplastic resin and having a fluid flow path formed of a groove and/or a hole in a junction face are vacuum-packed in a state in which the joined members are joined to each other. After a wrapped body obtained by the vacuum-packing is heated to soften the joined members, the joined members are welded to each other through the junction faces by applying fluid pressure to an entire outer periphery of the wrapping to evenly pressurize the wrapping from a periphery. Then, the pressurization is cancelled to cool the welded joined members.