| 摘要 |
PURPOSE:To embody a good workability and an ease of production by a method wherein a hollow body having a specific internal shape is blow molded, the hollow body is packed with globular granules, a synthetic resin is injection molded onto the outer surface of the hollow body, and the granules charged in the hollow body are removed. CONSTITUTION:In a blow molding process, an inner hollow branch pipe 1 is blow molded. In this case, branch pipe parts 2 are longer than branch pipe parts 4 of an outer hollow branch pipe 3. In a globular granules packing process, glass beads 5 are packed closest into the inner hollow branch pipe 1 so as to prevent the deformation of the inner hollow branch pipe 1 by an injection pressure to be applied in the next process. In an injection molding process, the inner hollow branch pipe 1 packed with the glass beads 5 is set in a mold, and the outer hollow branch pipe 3 is integrally molded on the outer surface of the inner hollow branch pipe 1 using a polybutylene terephthalate as a synthetic resin. |
