Reduce Residual Stress In Injection Molding Process Of Thin Wall

As a new type of plastic polymer material, because of its superior performance and ease of processing, etc. it has been widely used. Injection molding process as an excellent plastic production and processing technology in the plastics processing industry occupies an important position, but because of the inherent molding injection molding way, the inevitable presence of residual stress in injection varieties. Experiments show that injection products war page occurring in the storage and use of negative phenomena and cracking is essentially due to the residual stress of injection molded parts inside the unit; another study shows the effect of injection molded products optical properties, electrical properties, physical properties and one important factor is the quality of appearance of residual stresses. Therefore, the injection molding process to identify factors influencing the residual stress and to study their impact on the regularity of residual stress, so the majority of molding technology staff to take effective measures to reduce the residual stress within the molded parts, and as far as possible so that the residual stress in injection molded parts evenly distributed, which is to improve the quality of injection molded products has important significance.LCD display front frame is the main structure of a liquid crystal display. Product has a size large, structurally weak, meat thickness and other characteristics that are more vulnerable to residual stress. In order to work out the impact of process parameters on residual stress, the first use of residual stress between the theoretical study of molecular formation mechanism and influence of various factors using mold flow analysis methods on residual stresses. Then use orthogonal test data flow analysis for mold specific numerical analysis, and finally to verify the size and regularity of residual stress test by way of actual physical testing of products.Conclusions are as follows:1. The residual stress mainly by the injection molding process feed stream flow and thermal variations resulting in residual stress,And the whole molding process, pressure, temperature, time changes are changes in the size of the residual stress in injection molded parts influential;2. Display box before injection products for the research model, to achieve reconstruction in Moldflow in accordance with the existing mold by mold flow analysis, the residual stress of rapid change at the gate and the two gates in the middle position. After the simulation results and the actual test temperature has been deformed position.3. By single factor simulation test, we found that as the barrel temperature, mold surface temperature, the injection of residual stress decreases; as the holding pressure increase, the residual stress increases at the gate; increases dwell time, the residual stress decreases, but greater than 3.8s dwell time does not change substantially after the residual stress. Injection time 2s, 25 s is the best position the cooling time, the time will increase or decrease the residual stress increases.4. Plastic front frame of ABS material to display products for the research model, by orthogonal experiment affect significant degree of residual stress in descending order: packing pressure, melt temperature, mold temperature, injection time, cooling time, residual stress the smallest combination of process parameters as A4B4C3D1E1, which melt temperature 260°C, tooling temperature 80°C, cooling time 25 s, injection time 2s, holding pressure 80 MPa.The research results can improve large size thin wall injection products residual stress, and can solve the actual production of stress deformation and cracking problems. Provide truly effective reference for improving the injection molding process, improve the quality.