The Weld Improvements Injection Molded Parts And Numerical Simulation,

With the development of science and technology, plastics have grabbed people's eyes by its unique performances:low density, high specific strength, good dielectric performance and electrical conductivity, as well as possessing wear resistance, seismic resistance, chemical resistant property and convenient processing, which are widely used in electronic instruments and meters,communication tools, the agriculture, the fishery, the packing industry and the small daily necessities. Plastic injection process, as one of the most important methods, also has highly obtained people's attention. After years'development and research, the technique becomes gradual perfection, so plastic products are widely used in industries from all walks of life. But with the extension of application scope, the demand for comprehensive performance is much stricter, especially in automobile manufacture and electrical appliances industries.Weldline is one of common injection molding flaws. It has affected appearances of workpiece, and seriously reduced the mechanics performance; more seriously, it has slowed down the development of relative industry. The following are the main contents of this paper:Firstly, this paper emphasizes on studying the morphology during the melt-flow process, and microscopically explained how the weldline forms. At the same time, it analyses the configuration and structure of weldline and the appraisal has made the detailed elaboration to the performance.Secondly, to find out the law of process parameters influence on thermoplastic plastics with or without weldlines, experiments are carried on taking ABS dumbbell-shaped plastic sticks as example. Then, using Taguchi method, orthogonal tests are designed to study the injection process of two different thermoplastic materials"Dumbbell-shape"workpiece, optimize their parameters and find the influence degree of the different parameters to weldline performance. It is tested by experiment that for non-crystal plastic ABS, the biggest influence factor is injection temperature, while for crystal plastic PE is injection pressure. So when solving melt-line flaw by optimizing process parameters, we should start changing from the major factors, so that can get twice the result with half the effort.Thirdly, three technologies are introduced in this paper to decrease the influence of welt line, especially the multi-spot Sequence Valve Gates (SVG) which is an effective method for solving the melt line problem.Fourthly, we tested the experimental results by software, Moldflow. According the simulation, we find rhombic cold slug well has a better effort to increase the mechanical property of plastic parts. At last, we also simulate the SVG in Moldflow, validated the conclusion.