Patent ID: 11906077
Assignee: YACHIYO INDUSTRY CO., LTD.
Field: Other special machines (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 1:
2. A filler pipe manufacturing method, comprising:
an extrusion step of extruding a tubular material including at least an inner layer, a barrier layer, and an outer layer; and
a forming step of forming a bellows section that includes a peak and a valley and an ordinary section that does not include the bellows section by transferring part of the tubular material to forming surfaces of a plurality of split forming molds while moving the plurality of split forming molds, wherein
in the extrusion step, an inner layer of the tubular material is set to be thinner than the outer layer, and
in the forming step, the outer layer of the bellows section is sucked to transfer the tubular material to the split forming molds, the inner layer in the bellows section is adapted to be thinner than the inner layer in the ordinary section and, setting is made such that an increase rate of an inner layer proportion in the peak of the bellows section with respect to an inner layer proportion in the ordinary section after the forming is equal to or less than an increase rate of an outer layer proportion in the peak of the bellows section with respect to an outer layer proportion in the ordinary section.