| 摘要 |
PURPOSE:To mold a tube with smooth and excellent surface roughness by providing, by the largest roughness indication, the surface roughness of a tube inner surface obtained by quick cooling which is a specific surface roughness or lower. CONSTITUTION:An extruder 2 is driven so as to move the melted resin 1a along a fluidity conduit 7 and guide pipe 8, and a semi-melted tube 1b is guided by a coolant supplying pipe 10 and pressed into the gap between the diameter contraction hole 4a of a sizing die 4 and coolant supplying pipe 10. The semi-melted tube 1b is contraction diameter-molded at a predetermined outer diameter through the diameter contraction hole 4a, and a valve 11 is opened in order to supply the coolant C filled in a tank 12 to the coolant supplying pipe 10 and by the coolant C spouted forcefully, the inner surface of the semi-melted tube 1b which is melted in an amorphous state is cooled quickly at -30 deg.C or lower. The inner surface of the tube 1b is quickly solidified and the crystallization is restrained, and thus the numbers of the superficial recesses and protrusion are suppressed, as a result, the largest surface roughness in the inner peripheral surface is molded in being 1mumRmax or below and in smooth and excellent surface roughness. The tube 1b is soaked into the cooling liquid W of a cooling bath 5, thereby manufacturing the tube 1b while being subjected to a cooling treatment. |
