In recent years, LED TVs are gradually becoming the mainstream of the market due to their energy-saving, environmentally friendly and slim characteristics. Large-size LED TVs mainly use plastic shells. Due to the narrow frame of the front shell of the TV and the thin thickness of the whole machine, the dimensional stability of injection moulded products is high. Therefore, high-end technologies such as high-gloss non-melt injection moulding and double color moulding are commonly used in the plastic shell of LED TVs.
Double color injection moulding is a technology that can produce high-gloss plastic parts with two layers of different colors inside and outside at one time.
Large-scale double color injection moulding uses a large-scale rotary table double color injection moulding machine. After the mould is closed, the outer layer of plastic is injected. After the mould is opened, the cavity with the plastic part rotates 180° with the rotary table. After the mould is closed again, the inner plastic is injected. Open the mould and eject. In continuous production, the outer layer injection and the inner layer injection are carried out at the same time, so the moulding cycle is basically close to conventional injection moulding.
Compared with ordinary moulds and small double color injection mouldings that have been widely used at present, double color moulds are very different in terms of product characteristics, mould structure, action sequence, gate settings, runner layout, etc., and the difficulty is greatly increased. Since the inner and outer layers are injected separately, the double color mould requires two sets of cavities and two sets of cores. The two sets of cavities must be identical and can be interchangeable with the two sets of cores; both sets of gating systems are set in the mould The core side is a reverse installation structure; the ejector is also located on the core side, and hydraulic ejector is used. Coupled with the cooling system, the complexity of the entire core side structure is greatly increased.
In terms of the moulding process, when the large double color injection moulding technology is used for the second moulding, the plastic flows along the surface of the first moulded plastic part, which is prone to injection defects such as bubbles, chromatic aberration, and run-out. It is necessary to repeatedly debug and adjust the injection process parameters. Precise control, and improve and optimize the mould according to the moulding situation.
The large-scale double color high-gloss injection moulding technology has high production efficiency and good surface quality. The colors of the inner and outer layers can be flexibly matched according to needs, which can greatly improve the appearance and quality of the whole product. At present, this technology is being used more and more widely in large-size LED TVs, and it has broad market prospects in high-end refrigerators, air conditioners and other home appliances in the future.