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Analysis of the application of two-color vertical injection molding machine technology in the manufacture of household appliances molds

Jun 15, 2020

Two-color vertical injection molding machine is a technology that can produce high-gloss surface and have two different layers of color matching plastic parts inside and outside in one molding. The application of this technology can greatly improve the appearance of the product. Compared with ordinary molds and the small two-color/two-component injection molding that has been widely used now, large two-color vertical injection molding machine molds have very different angles in product characteristics, mold structure, motion sequence, gate setting, runner layout, etc. The difficulty is greatly increased.


    In continuous production, the outer layer injection is performed simultaneously with the inner layer injection, so the molding cycle is basically close to conventional injection molding. The technology of large-scale two-color vertical injection molding machine can be combined with high-gloss non-melting injection molding technology. High-temperature and high-pressure hot water or steam is used in the production to heat the mold, and the cooling medium is quickly switched after the injection is achieved to quickly cool the mold to obtain a non-melting surface. The two-color plastic parts with high marks and high gloss can obviously improve the appearance of the whole machine. According to the China Mold Network, the large two-color vertical injection molding machine adopts a rotary large-scale two-color vertical injection molding machine. After the mold is closed, the outer plastic is injected. After the mold is opened, the cavity rotates 180° with the rotary table with the plastic parts. After the mold is closed again, the inner layer of plastic is injected, and finally the mold is ejected.


    Because the inner and outer layers are injected separately, the mold of the large two-color vertical injection molding machine requires two sets of cavities and two sets of cores, of which two sets of cavities must be exactly the same, and can be interchanged with the two sets of cores; two casting systems They are all set on the core side and belong to the reverse mounting structure; the ejection is also set on the core side, adopting hydraulic ejection. Coupled with the cooling system, the complexity of the entire core side structure is greatly increased.


    From the perspective of optimizing the design of plastic parts, the shape of the outer layer of the first molding needs to be as simple as possible. The inner layer of the second molding can be designed with ribs, columns and other structures, but the gate layout and the flow pattern must be fully considered. Analysis to optimize the design. In order to make the appearance surface of the plastic parts show the effect of color gradual change, the wall thickness of the outer circumference can adopt a gradual design from thin to thick.


    From the perspective of the molding process, when the large-scale two-color vertical injection molding machine technology is molded for the second time, the plastic flows along the surface of the plastic part that is molded for the first time, and it is prone to injection defects such as bubbles, color difference, and glue running. Repeated debugging and precise control, combined with molding conditions to improve and optimize the mold.


    Through hard work and breakthroughs, a series of core technologies have been broken through. The first domestically developed large-scale two-color high-gloss injection mold that has reached the international advanced level has been successfully applied to Hisense's large-size LED-backlit LCD TVs. The large-scale two-color high-gloss injection molding technology has high production efficiency and good surface quality. The inner and outer colors can be flexibly matched according to needs, which can greatly improve the appearance and grade of the whole product. At present, this technology is getting more and more widely used in large-size LED-backlit LCD TVs, and it will also have a broad market prospect in high-end refrigerators, air conditioners and other home appliances in the future.