| 摘要 |
PURPOSE:To make molten resin into a foamed molded article based on a gas counterpressure method, which has no weld line and is superior in appearance, by a method wherein injection molding is performed by providing a protrusion on the inside part of a mold corresponding to a weld line to be formed by meeting the molten resin injected and cast through a gate part and a circumferential part of the weld line and an unfoamed thin part is formed on the protrusion. CONSTITUTION:A position of a weld line A to be generated through a shape of an expanded molded article to be manufactured is confirmed and a protrusion 4 is provided on the inside part of a mold corresponding to the position. As for the protrusion, though a shape is not limited especially, the same is a thing having a height generating resistance varying a rate of flow of a resin flow and a width of the same is made into constant one which is in the same direction with the weld line A. As the resin flow becomes fast and resin pressure is increased due to a decrease of a cross-sectional area in the inside of a cavity of this part by providing the protrusion, foaming of the resin is controlled and generation of the weld line can be prevented.
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