| 摘要 |
PURPOSE:To manufacture a resin pipe which possesses a highly smooth inner circumferential surface and is highly suitable for a piping for ultrapure water, by a method wherein the inner circumferential surface of a pipe material is made into a molten state by heating the same up to a predetermined temperature and upon extrusion of the same the pipe material is cooled while the same is being kept at a state wherein the diameter is expanded by blowing a cooling air flow against the inner circumferential surface. CONSTITUTION:An inner circumferential surface of a pipe material 30 is heated up to a predetermined temperature by a heating device 16 and extruded by making the inner circumferential surface into a completely molten state. A cooling air flow is blown against the inner circumferential surface of the pipe material 30, which is directly after extrusion through an extrusion mold 10, through a blow-off port 21 of an auxiliary mandrel 20 and the pipe material 30 is cooled while a state wherein the diameter of the same is expanded and the inner circumferential surface of the same is highly smooth is being kept on. As for the pipe material 30, the cooling water is sprayed over the inner circumferential surface of the pipe material 30, which is directly after passing through the tip of the auxiliary mandrel 20, and the inner circumferential surface is cooled down to a predetermined temperature. With this construction, the inner circumferential surface of the pipe material 30 is solidified under a state wherein the same is highly smoothed without restoring unevenness. Then the pipe material 30 is cooled from the external circumferential surface by a cooling water tank not illustrate herein, which is cut off in predetermined lengths and made into a product. |
