PURPOSE: To obtain a desired shape of a pipe, e.g., a square pipe having a large curvature at a corner, by providing a plurality of female split molds at both sides of a male mold, and closing said molds while a free end portion of a sheet material is wound around the outer peripheral surface of said male mold.
CONSTITUTION: While a pair of female molds 16, 17 are opened, a sheet material 2 molded in advance into a U-shape is set on a male mold 15. After the sheet material 2 is completely set, a positioning pin 24 is pulled up, and simultaneously a pair of female molds 16, 17 are closed. As a pair of female molds 16, 17 are closed, the inner surfaces in the upper part of the molds 16, 17 are closely adhered to the upper corners of the sheet material 2 on the male mold 15. On the other hand, the inner surfaces in the lower part of the molds 16, 17 bend free end portions of the sheet material 2 protruding downward from the both sides of the male mold 15 along the lower corners of the male mold 15. A molten resin is ejected from a resin ejection nozzle 52, which flows first through an injection hole 50 into a mold which is a bottom wall 11b of a container 11. Then, the molten resin, running through a lower annular groove 56 and a communicating groove 57, fills an upper annular groove 55.
Ootsuka, Katsushige
Kuramitsu, Mikihiro
Watanabe, Tsunehisa
Odaka, Shoji
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