| 摘要 |
PURPOSE:To make it possible to obtain a homogeneous molded part with minimum mold shrinkage factor in a short time by a method wherein a melt is put fully longer time than the time necessary for conduction of heat in the molt in lowering its temperature and reducing its pressure in the vicinity of its glass transition point and quenched at a temperature before and after its glass transition point. CONSTITUTION:A melt injected in a cavity is quenched under dwell state down to just before the glass transition point peculiar to the melt. During the period ranging from the point just before the glass transition point peculiar to the melt to the point just after the glass transition point peculiar to the melt, the melt is put fully longer time than the time necessary for conduction of heat in the melt in the cavity in lowering its temperature while the specific volume of the melt being kept at the specific volume of the melt at normal temperature and normal pressures. At the same time, the pressure of the melt is reduced in inverse ratio to the elastic modulus of the melt, which increases as the lowering of its temperature. During the period ranging from the point just after the glass transition point peculiar to the melt to the release temperature of the melt, the melt is quenched under a dwell state. The sharp reduction of molding time is possible, because the melt is quenched within the regions, which give no effect to the molding quality, though the melt is imparted with enough time in passing through the glass transition point. |
