| 摘要 |
PURPOSE:To reduce difference in thickness of injection resin and cool melted resin faster so as to mold easily by injecting thermoplastic resin into an inner face of a recess of a metal pipe coupling for a plurality of times. CONSTITUTION:First injection molding dies 21-23 are inserted into each end part of a malleable cast iron pipe coupling tee body 1. Melted resin is injected into a cavity 55 from a runner 3 in the die 21 through a gate 4, cooled and solidified so as to set a thickness of a resin-coated layer 55 to 1/2 of a final thickness. As the coated layer 55 is in contact with the metal face of the body 1, cooling speed becomes faster. Next, the dies 21-23 are removed and dies 61-63 for final shape are inserted into the coupling body 1 having the resin layer 55, and injected into a cavity 85 from a runner 7 through a gate 8 so as to be solidified. Then, the dies 61-63 are removed. The resin layers 55 and 85 are fixed at an uneven part 10 formed in the corner of the resin layer 55. Accordingly, the resin layer can be cooled faster and working will be easy. |
