| 摘要 |
A mold apparatus and method is used to form a solid injection molded plastic part having no internal voids, a Class A finish, a sink-free exterior appearance surface, and unevenly distributed structural detail extending from the opposite surface, the detail including free-standing reinforcement ribs, attachment bosses, and the like. A charge of hot melted thermoplastic and pressurized gas are sequentially injected into a mold cavity defining the shape of the desired part, the plastic not filling the cavity and being simultaneously received in shaped recesses and grooves which form the structural detail. The pressurized gas forces the hot plastic from one mold half against the other mold half, and into the recesses and grooves, and is maintained during cooling. A gas seal is formed by the plastic to prevent gas in the mold cavity from reaching the finished exterior surface of the part during shrinkage of the plastic. Gas inlets and plastic volume areas cooperate with rib forming chambers to enhance resin distribution in the cavity. Importantly, the gas can be reclaimed, such as for recirculation and cooling.
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