| 摘要 |
PURPOSE:To easily realize the radially stretching of extrusion-molded synthetic resin pipe by a method wherein synthetic resin pipe, which is extrusion-molded, is radially stretchingly deformed with a radially stretching mold, the temperature conditions of which is nearly the same as those at extrusion molding and, when the pulling force is applied to the pipe by a pulling device, the radially stretching mold is cooled down to a temperature suitable for stretching and radially stretching is performed with the radially stretching mold under the condition just mentioned above. CONSTITUTION:Thermoplastic synthetic resin is tubularly extrusion-molded from a forming die 2. The resultant pipe P is radially stretchingly deformed under the condition being held at melt temperature with a radially stretching mold 3 and cooled and hardened at a cooling device 4 and sent to a pulling device 5. The pipe P is forcibly pulled out of the radially stretching mold 3 by being applied with pulling force. At this time point, an outer mold 32 is removed. After that, cooling water is sprayed over the outer mold 32 form a cooling shower device 33 and, at the same time, cooling water is circulated through the jacket 30 of an inner mold 31 so as to cool the extrusion-molded pipe P passing through a part, which is composed of the molds 31 and 32, of the mold 3 down to the temperature suitable for stretching in order to stretch the extrusion-molded pipe P at the radially stretching tapered part 3B of the radially stretching mold 3. |
