Papers by Author: Gang Gou

Abstract: Nowadays, with the rapid development of aerospace, auto, communication, consumer electronics and other fields, precision injection molding has been widespread concerned. P-V-T (Pressure-Specific-volume-Temperature) properties are inherent characteristics of polymers. In this paper, P-T parameters were set up in packing stage to achieve constant specific-volume control. Numerical simulation of P-V-T control strategy with Moldflow was carried out. Compared with conventional control strategy, the results showed that P-V-T control of precision injection molding could bring out more uniform density distribution, reduction in volume shrinkage and warpage of molded parts. It was concluded that the P-V-T control method could effectively improve the molding quality of the plastic product.

Abstract: Defects such as black spots and yellow surfaces appeared in the process of injection molding light guiding plate as a result of the failure surfaces of the screw and screw tip. To choose and optimize the solutions of different surface treatments of the special screw for light guiding plate, the stripping performance testing platform was established. The experimental results showed that TiN and TiAlN or similar coatings by physical vapor deposition could significantly reduce the adhesion force between polycarbonate (PC) and different coatings. Through surface topography analysis of diversified coatings with SEM and AFM, TiAlN coatings represented the excellent surface quality of its smoothness, continuum, and low surface wave. To enhance the bonding force between the molding screw and coatings, TiAlN/Cr and TiAlN/Ti multi-films was developed which owned much more firm bonding force than TiAlN and good surface quality to be suitable for the special screw for manufacturing light guiding plate.

Abstract: The light guide plate is an important element of the LCD backlight module which demands a certain degree of transparency and uniformity of gray. The defects such as black spots and yellow surface appeared when the light guide plate was processed by domestic equipments. The main problem was caused by the plasticization unit. The Influencing factors of performance for polycarbonate (PC) special screw were discussed in this paper. The conveyance capacity of melt in the metering zone of injection screws with different flight width and channel depth was analyzed by POLYFLOW software. In order to obtain high surface hardness, corrosion resistance and smoothness of PC special screw, surface coating processing was the key point for injection molding light guide plate. Moreover, the peel strength of PC with different coating processing metallic block was tested and measured. he experimental results of the analysis showed that the nickel-tungsten alloy plating and physical vapor deposition can significantly improve stripping properties, corrosion resistance and smoothness. The influencing factors of coating and PC materials’ stripping were analyzed. Through industrial testing, the defective rate of light guide plate had been greatly reduced with physical vapor deposition compared to the screw with hard chromium plating.