Composition and structure of the hottest plastic i

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Composition and structure of plastic injection mold

plastic injection mold is basically divided into static mold and dynamic mold

the static mold with sprue sleeve on the side of the injection head of the injection molding machine is generally composed of sprue sleeve, backup plate and template. Simple molds (especially those without a core) can also use a thicker template according to the correct steps without using backup plate. 1. The sprue sleeve is generally a standard part, and it is not recommended to cancel it unless for special reasons. The use of sprue sleeve is conducive to the installation of molds and convenient replacement without polishing by yourself. Some special mold sprue sleeves can be drilled out or cut with taper line. When a part of the mold must be demoulded by a static mold, a static mold demoulding mechanism must be added. The structure of the moving die is generally the moving die, the moving die backup plate, the demoulding mechanism, the die foot and the installation fixing plate

in the demoulding mechanism, in addition to the stripper rod, there is also a return rod, and some molds need to add springs to realize functions such as automatic demoulding. There are also guide posts, cooling water holes, flow channels, etc. are also essential to the basic structure of the mold. Of course, there are inclined guide boxes, inclined guide pillars and so on. When designing a mold for a product, we must first set the basic structural dimensions of the mold to prepare materials to speed up the mold manufacturing. For complex products, the product drawing should be drawn first, and then the size of the mold should be determined. Now the mold basically needs heat treatment, which can significantly reduce the friction coefficient of the film, increase the hardness of the mold, and improve the service life of the mold. Before heat treatment, the formwork shall be preliminarily processed: drill the guide pillar hole, return hole (moving die), cavity hole, screw hole, gate sleeve hole (moving die) cooling water hole, etc., mill the runner and cavity, and mill the inclined guide box for some molds. At present, the templates of ordinary precision molds generally use Cr12, Cr12MoV and some professional mold steels. The hardness of Cr12 cannot be pressed too high by hand. It often cracks at HRC60 degrees. The common hardness of templates is generally about HRC55 degrees. The hardness of the core can be above hrc58. If the material is 3Cr2W8V, the surface hardness of nitriding treatment after manufacturing should be above hrc58, and the thicker the nitriding layer, the better

gate is directly related to the beauty of plastic parts. At the same time, it can also improve the interface state between wood flour and polymer. If the gate design is not good, it is easy to produce defects. It is easy to produce serpentine flow without any obstruction. For products with high requirements, overflow and exhaust should also be designed. The ejector rod can be used at the overflow, and there should be no overflow flash on the formwork, so as not to affect the service life of the mold

there are more and more mold design software, and most of them rarely use pencils to draw mold drawings

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