| 摘要 |
PURPOSE:To remove moisture effectively from a molding material through a vent section by a method wherein at least one set of gear pump, provided at the outlet port of a material pressurizing unit, is provided while a deaerating device is provided at a vent section, provided at the upstream side of the gear pump, to make the pressure of the vent unit of the material pressurizing unit zero substantially even in case the extrusion molding is effected under a high pressure. CONSTITUTION:The vent section 18 is provided on the way of the material pressurizing section 12 at the upstream side of the gear pump 16 while the vent section 18 is provided with the deaerating device 20 such as a vacuum pump or the like. According to this constitution, a high pressure, such as 300-500kg/cm<2>, in the material molding section 14 or a crosshead is compensated by the delivery pressure of the gear pump 16 and a pressure at the immediately upstream side of the gear pump 16 is suppressed to a low-pressure of about 5-20kg/cm<2> by the pressurizing section (screw section) between the vent section 18 and the gear pump 16. In case the immediate downstream side of the vent section has a low pressure in such manner, the pressure in the vent section 18 may be made zero, therefore, the molding material will never be vent up and moisture may be removed from the molding material by the deaeration device 20 connected to the vent section 18. |
