To reduce a weight and cost by reducing the use amt. of a material at a part wherein an outer diameter is small even if the wall thickness of a produced diameter expanded straw pipe is increased to a degree capable of obtaining desired buckling strength.
An apparatus for producing a diameter expanded straw pipe wherein a diameter expanded part is provided to at least one end part of a long cylindrical body comprising a thermoplastic resin so that the inner and outer diameters thereof are increased toward the end part thereof has a diameter expanding mold part 31 wherein the diameter from the leading end 3a thereof to the base end 3b thereof is expanded from a diameter smaller than the inner diameter of the cylindrical body to the diameter larger than the outer diameter thereof and a stepped part 32 having a groove 33.
SUYAMA MINORU
BANBA TAKESHI
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