| 摘要 |
PURPOSE:To prevent pressurizing gas from forcibly entering basic thick part by a method wherein the cross-sectional area of a cavity between some part of thick-walled part to be hollowed and its extension part is made to be smaller at the hollowing of at least said part, of the thick-walled part performed by pouring the pressurizing fluid into the molten resin in the cavity. CONSTITUTION:Partitions 5 are provided between the thick-walled part 4 of a mold and their extension parts and made preferably to be forward and backward movable to the direction of a cavity. In addition, counter-pressure is preferably applied by charging pressurizing gas in the cavity before the injection of molten resin. After the injection of the predetermined amount of resin, the partitions 5 are advanced in order to make the cross-sectional area of the cavity smaller. Next, a needle 6 is advanced so as to pour pressurized gas in order to produce a hollow space in the molten resin and, at the same time, to push the molten resin towards the gap at the tip of the cavity, resulting in moving the molten resin so as to come into close contact with the mold. During this time, the counter pressure is released. Next, when the partitions 5 are retreated, the molten resin advances as the partitions 5 retreat, developing no defective part at the sites of the partitions 5 of a formed article. |
