| 摘要 |
PURPOSE:To prevent biting flaws from occurring by a method wherein a core body for forming the inside of a radially shrinkable pipe socket is inserted into one end of a plastic pipe, oddly divided pieces of an outer die having unparallel divided faces are shrunk radially to compress the outer circumference of said pipe and then remaining outer die pieces are shrunk radially. CONSTITUTION:For the purpose of forming the outer surface of a pipe socket on a plastic pipe, first, the divided pieces 22 of an outer die 2 which are provided with unparallel faces are shrunk radially. Then, the divided pieces 21, 21 having divided faces parallel to each other are shrunk radially along the divided faces between the divided pieces 22, 22 to compress the outer circumference of the plastic pipe 3. At this time, there is not any clearance between the divided pipes 21, 21 of the outer die and other divided pieces 22, 22. Since contact between the inner surfaces 21A of the divided pieces 21, 22 and the plastic pipe 3 starts from the swollen parts, plastic material does not bite into the contact surfaces between the divided pieces 21, 22. |
