| 摘要 |
PURPOSE: A method for manufacturing a double pipe is provided in which an adhesion part of the double pipe is stably cohered even though an external environment is changed. CONSTITUTION: The method for manufacturing a double pipe comprises a first step(S1) of forming a synthetic resin pipe in a double structure; a second step(S2) of inserting the synthetic resin pipe into a metal pipe after first step(S1); a third step(S3) of heating the metal pipe after the second step(S2) so that adhesive resin of the synthetic resin pipe is heated to a softening point thereof; and a fourth step(S4) of discharging air between the inner surface of the metal pipe and the outer surface of the synthetic resin pipe, thereby vacuuming the space therebetween after third step(S3) so that the metal pipe is adhered onto the synthetic resin pipe, wherein the synthetic resin pipe is made of adhesive resin and polyethylene, an outer layer of the synthetic resin pipe is formed of adhesive resin of polyolefin, the metal pipe is heated by a high frequency induction heating means, and the high frequency induction heating means uses high frequency, low frequency and gas. |
