Technological Development of Fluid Control Within Metal Mold for Application to Family Mold of Resin Part
Atsushi Mizutani†, Takeshi Nagao, and Naoki Arai
Nissan Motor Co., Ltd.
1 Natsushima, Yokosuka, Kanagawa 237-8523, Japan
Today, many of the resin parts of automobiles are molded using the injection molding technique with high productivity. In the case of a large part, for which a mold clamping force of more than 2,000 t is needed, it is common that a piece of the part is manufactured with one metal mold and the parts with bilateral symmetry are manufactured simultaneously with a separate one. This development focuses on the advantage that productivity could be enhanced and the cost for a metal mold could be reduced by utilizing the space in the mold cavity for a large part and making another metal mold for a small part. To mold a large and small part with a large volume ratio simultaneously by using one metal mold, the fluid distribution of molten resin suitable for the volumes of both parts is necessary. Without realizing the associated fluid distribution molding defects, such as short, sink, or the like, would occur. In the case of the large part, such as a bumper, molten resin flows from the injection unit through a hot runner unit within the metal mold and subsequently, each gate into each product. To distribute the appropriate amount of resin to the large and small parts through a hot runner, the molding technique involves distribution of the fluid to each gate with an appropriate balance by controlling flow through the valve of a hot runner; this paper discusses the aforementioned technique. Because the energy and the power of the molding machine to melt and inject the resin can be reduced by molding two deferent parts with one die, this family mold can contribute to Green production.
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