Simulation Of Thermal Deformation Of Plastics Gear Molded By Injecting And Its Mold Optimization

In this paper, based on requirements of the tubular reducer for improving the quality of plastics gear molded by injecting, some important factors which affect the accuracy of the size and shape during gear injection molding processing were discussed according to the experimental study and theoretical analysis. And the thermal deformation during the injection molding was simulated and analyzed by using the finite element software ANSYS. On this basis, the optimization design method of plastics gear injection mold was proposed.The shrinkage mechanism of injection molding and the main influencing factors were systematic analyzed, and then the, injection technology was studied. The size of injection-molded parts in different pressures and temperatures were experimentally measured and analyzed. The effect of injection molding technology on the forming shrinkage was also studied in order to minimize the injection molding shrinkage and to reduce the error. The Taguchi experimental design theory was employed to optimize production process parameters, which provided the suitable parameters for improving gear injection molding technology and quality.For correctly simulating and analyzing the thermal deformation of plastics gear molded by injecting, the thermal expansion coefficient of Nylon composite materials was measured. Combined with the injection experimental data, the phase transformation and thermal shrinking rates were calculated.The demoulding cooling model was established by finite element analysis. And cooling deformation process was simulated by the coupled thermal stress mode in ANSYS software. The results showed that deformation of the gear tooth profile was caused by the shrinking.In order to improve the accuracy of injection gear, an error compensation method was proposed to optimize the design of injection mold cavity on the basis of the error analysis due to thermal deformation, which is a reverse engineering method. Firstly, tooth profile shape parameter was reversely solved based on the room temperature standard gear in ANSYS software, and the list of point coordinates correspondding to the mold cavity profile was obtained through the phase transformation shrinkage. Finally, the curve fitting of cavity nodes was accomplished by MATLAB software to obtain the curve used to CNC machine cutting. In this study, the practical application of finite element analysis was tried to analyze the injected plastics gears, which had good practical value to the improvement of injection molding technology and injection mold design.