| 摘要 |
PURPOSE: To produce a reducer constituted of large and small diameter pipe parts, keeping a required dimension over a long period of time and constituted so as not to be deformed even if heated and welded. CONSTITUTION: At first, the end part 21 of a raw pipe 20 molding a small diameter part is heated to about diameter reducible melting temp. and the heated end part 21 is forcibly inserted into the diameter reducing part 13 continued to the diameter expanding part of the through-hole 11 bored in a mold 10 to be reduced in its diameter to mold the small diameter pipe part. Next, the small diameter pipe part is annealed at temp. slightly higher than heating temp. When medium density polyethylene is used as the raw pipe 20, melting temp. is set to about 120 deg.C. |
