Application of two - color injection molding technology in the manufacture of household appliance mold
Two-color injection molding is a technology that can produce a high surface gloss and two different colors inside and outside the plastic parts in one molding. The application of this technology can greatly improve the appearance of the whole machine product. Compared with the ordinary mold and the small two-color/two-component injection molding that has been widely used at present, the large two-color injection molding mold has great differences in product characteristics, mold structure, action sequence, gate setting, flow channel layout and other aspects, and the difficulty is greatly increased.
In continuous production, the outer layer injection and the inner layer injection are carried out at the same time, so the molding cycle is basically close to the conventional injection. Large two-color injection molding technology can be combined with high-light non-weld injection molding technology, the production of hot water or steam heating mold, and quickly change the cooling medium after injection to quickly cool the mold, the surface of the two-color plastic without weld and has a high gloss, can significantly improve the appearance of the machine. According to the introduction of Huaxia mold net, large two-color injection molding using rotary table large two-color injection machine, after closing the mold first for the outer plastic injection, after opening the mold cavity with plastic parts rotating 180 degrees with the rotating table, again after closing the mold for the inner plastic injection, finally open the mold out.
Because of the internal and external injection molding, large two-color injection mold needs two sets of cavity, two sets of core, two sets of cavity to be identical, and with two sets of core can be interchangeable; The two pouring systems are located at the core side, belonging to the reverse loading structure; Ejection is also located in the core side, using oil pressure ejection. Coupled with the cooling system, the complexity of the core side structure is greatly increased.
In the optimization design of plastic parts, the outer shape of the first molding needs to be as simple as possible, and the inner layer of the second molding can be designed with bars, columns and other structures, but the gate layout and material flow form must be fully considered, and the optimization design needs to be carried out through CAE analysis. In order to make the appearance of the plastic parts show the effect of gradual change of color, the wall thickness along the outer ring can be adopted from thin to thick gradient design.
In the molding process, the second molding of large two-color injection molding technology, the plastic along the surface of the first molding plastic flow, easy to appear bubbles, color difference, running glue injection defects, need to repeatedly debug and accurate control of the injection process parameters, and combined with the molding situation to improve and optimize the mold.
Through efforts, we have broken through a series of key technologies, and developed a large two-color highlight injection mold that has reached the international advanced level in the first domestic company, which has been successfully applied to Hisense's large-size LED backlight LCD TV. Large two-color highlight injection molding technology has high production efficiency and good surface quality, and the internal and external two layers of color can be flexibly matched according to the needs, which can greatly improve the appearance effect and grade of the whole machine product. At present, the technology is being increasingly widely used in large-size LED backlit LCD TVS, and has a broad market prospect in the future in high-end refrigerators, air conditioners and other home appliances.