| 摘要 |
PURPOSE:To improve the transferability of a cavity by a method wherein molten expandable resin is injected in the mold cavity under the condition that gas pressure is applied to the mold cavity and, after that, the predetermined part of the mold cavity is pressurized in the predetermined time so as to press the resin against the predetermined cavity surface. CONSTITUTION:After a mold is closed and a nozzle is touched, gas pressure, which is higher than the blowing pressure of molten resin, is applied to a gas manifold 8. The gas pressure enhances the pressure in a mold cavity 1 through gas slits 2. Next, molten expandable resin 4 is injected from a nozzle 18. At this time, the expandable resin 4 comes into contact with a cavity surface under the un-expanded state, resulting in turning into semi-hardened state, in which only the surface of the resin is cooled. Just before the completion of the filing of the resin, the pressure in the mold cavity is removed from the gas manifold 8 so as to expand the interior of the resin, which is still in molten state, in order to complete the filing of the resin. Just after that, high pressure gas is poured in a high pressure gas manifold 21 so as to pour the high pressure gas from high pressure gas slits 20 in the cavity 10 in order to press the semi-molten resin 4 against a surface 19, through which favorable transferability is expected to be obtained, resulting in obtaining a molded item having favorable transferabilty through cooling. |
