| 摘要 |
PURPOSE:To manufacture a double pipe continuously at favorable reproducibility, by forming a double pipe through extrusion by using an extrusion molding machine with a crosshead die and sizing die equipment in common. CONSTITUTION:Thermoplastic resin which has passed through a resin path 18 from a discharge port 13 of a crosshead die 11 is extruded around the circumference of an internal pipe 1' concentrically while supplying a long-sized internal pipe 15 continuously to the crosshead die 11. It is preferable that an external tubular material 14 of specials directly after extrusion through the crosshead die 11 does not come into contact directly with an external circumferential surface of the internal pipe 15 and an appropriate gap lies between the external circumferential surface of the internal pipe 1' and the tip of a protruded line 3. The external tubular material 14 of specials is moved under a state where the same is stuck close to an internal wall of a sizing die 12 through suction through a fine through hole 21 of a pipe wall 23, cooled with a refrigerant circulating in the interior or the exterior of the pipe wall 23 and solidified. Consequently, a double pipe 20 wherein an external shape of the molded external pipe of specials is adjusted precisely so that the same becomes the target dimensions and the tip fringe of the protruded line 3 of the odd-shaped external pipe is fused to the external circumferential surface of the internal pipe is formed. |
