注塑模具英文3翻譯-文庫吧
2024-10-16 21:12 本頁面
【正文】 new molding and mold materials that may affect these rules. D. The Basic Mold 1. Mold Cavity Space The mold cavity space is a shape inside the mold, ”excavated”(by machining the mold material) in such a manner that when the molding material(in our case, the plastic)is forced into this space it will take on the shape of the cavity space and, therefore, the desired product The principle of a mold is almost as old as human civilization. Molds have been used to make tools, weapons, bells, statues, and household articles, by pouring liquid metals (iron, bronze) into sand forms. such molds, which are still used today in foundries ,can be used only once because the mold is destroyed to release the product after it has solidified. Today, we are looking for permanent molds that can be used over and over .Now molds are made from strong, durable materials, such as steel, or from softer aluminum or metal alloys and even from certain plastics where a long mold life is not required because the planned production is small. In injection molding the (hot) plastic is injected into the cavity space with high pressure, so the mold must be strong enough to resist the injection pressure without deforming. 2 . Number of Cavities Many molds, particularly molds for larger products, are built for only 1 cavity space(a singlecavity mold),but many molds, especially large production molds, are built with or more cavities. The reason for this is purely economical. It takes only little more time to inject several cavities than to inject one. For example, a 4cavity mold requires only (approximately) onefourth of the machine time of a singlecavity mold. Conversely, the production increases in proportion to the number of cavities. A mold with more cavities is more expensive to build than a singlecavity
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