Resin filler tube and manufacturing method for the same

A resin filler tube to be welded to an outer circumferential edge of an opening hole of a fuel tank, the resin filler tube comprising:

• a tubular body having an outermost layer formed by using an outermost layer material, and one or more inner layers each formed by using an inner layer material;
• a flange having a plurality of layers that are of same kinds as those of the tubular body, the flange having a diameter greater than an outer diameter of the tubular body, a thickness greater than a thickness of the tubular body, and a predetermined width in an axial direction, the flange having a first axial end face forming a weld surface to be welded to the outer circumferential edge of the opening hole of the fuel tank;
• a base-end-side reverse tapered portion having a plurality of layers that are of same kinds as those of the tubular body, the base-end-side reverse tapered portion connecting between an end of the tubular body on the fuel tank side and an end of an outer circumferential surface of the flange on a side opposite to the fuel tank side, the base-end-side reverse tapered portion being reversely tapered so as to increase a diameter toward the flange;
• a leading end tubular portion having a plurality of layers that are of same kinds as those of the tubular body, the leading end tubular portion being located at a leading end side of the resin filler tube, and located radially inward of the opening hole of the fuel tank or located inward of an inner wall surface of the fuel tank;
• and
• a leading-end-side tapered portion having a plurality of layers that are of same kinds as those of the tubular body, the leading-end-side tapered portion connecting between a radially inner portion of the flange and an end of the leading end tubular portion on the tubular body side, the leading-end-side tapered portion being tapered so as to have a diameter increased toward the flange, wherein:
• the base-end-side reverse tapered portion is formed so as to have an inner diameter that is not less than an inner diameter of the tubular body over an entire range in the axial direction, and
• the leading-end-side tapered portion has an inner diameter that is not less than an inner diameter of the leading end tubular portion over an entire range in the axial direction.