Research On Key Technology Of Light Guide Plate Precision Injection Molding Equipment And Processing Condition

This article researched on equipment and processing for injection molding transparent optical precision products—light guide plate . The light guide plate was an important element of the LCD backlight module. It demanded a certain degree of transparency and uniformity of gray. Small size light guide plate was made by injection molding. If the light guide plate could be made by our country's injection molding equipment reflected the level of our country's injection molding equipment.When the light guide plate was injection molding by domestic equipment, the defects such as black spots,yellow were appeared . The main problems was the plasticization body' Failure . The plasticization body for injection molding light guide plate was researched on this paper. A special screw for injection molding lightguide plate was designed. Injection screw was one of the most key parts of injection molding machine that affected the melt conveying performance and plasticization effect directly. It was very necessary for improving the quality of product to establish a reasonable structure of injection screw. Utilized POLYFLOW, a CFD software to have three dimentional simulation for melt body in the metering zone of injection screws with different flight width,channel depth. By simulation, the effect on performance of PC melt conveying from different structural screws was discussed.Surface modification treatment was the key to designe the special screw for injection molding lightguide plate. The purpose of surface treatment was to obtain high surface hardness, corrosion resistance and smoothness. And good stripping performance with PC materials was the most important. Tested and measured the peel strength of PC with test block of different surface treatment. From the experimental results, nickel-tungsten alloy brush plating,Physical vapor deposition, the tow of surface treatment processing can significantly improved stripping properties,corrosion resistance and smoothness. Compared to the screw of hard chromium plating, Commissioning of screws with physical vapor deposition and ion implantation surface treatment showed that the defective rate of lightguide plate products had been reduced. In the end of trial run, physical vapor deposition surface treatment screw was in good condition. The hard chromium-plated screw Coating was invalidated, and was adhered degradation PC material. The influencing factors of coating and PC materials' stripping performance were Analysed.The injection molding processing of the light guide plate was Simulated and analysed by using Moldflow. The light guide plates' simulations under the conditions of the different packing conditions, mold temperature, melt temperature, cooling loop, and so on, were completed. Through the warpage, residual stress and the shrinkage rate of comparative analysis, the best injection molding processing parameters of the light guide plates were ultimately determined.