Study On Numerical Simulation And Optimization Of Process Parameters Of Rapid Heating Cycle Molding Process

As an important method of Plastic molding, Plastic injection molding process is a wide range of applications in the various areas in the national economy. However, with the application of plastic products becomes more extensive, there was a higher demand on accuracy of plastic products, shape, function and cost. So that, the traditional injection molding process has been difficult to adapt to such a request.Rapid Heating Cycle Molding technology is a new scar-free welding and high smoothness of the plastic molding technology, superior access to the appearance of plastic products. Such as: no weld line, no flow marks, no silver line, with high-gloss, the surface of plastic products not to expose the strengthening additives such as glass fiber, the good effectiveness of transfer, and the higher physical properties and so on. It can be achieved the effectiveness almost of the Perspex protection screen which is used in the current flat-panel television. It even can be used to directly product the shell of flat-panel television which can be replacing and spraying methods such as paste to protect screen. The use of the technology not only can directly reduce the cost of plastic products, but also receive significant reduction in the volume of spray, or even abolish the spraying process. It can save the high cost of secondary processing, then reduce production costs greatly, which can obtain a significant reduction in environmental pollution caused by spraying.In accordance with the requirements of Rapid thermal cycling in injection molding technology, this paper studies its Process Principle and technical characteristics, then introduces the common method to achieve for the Die fast heating. Research proposed Rapid thermal cycle injection mold temperature control method for real-time dynamic and key technologies which used high temperature and high pressure water vapor heating / cooling water cooling to achieve rapid mold heating and rapid cooling, which laid the foundation for engineering applications from the study of the mechanism and principle for the process. This paper Introduces components of rapid thermal cycling of steam injection heating system, and gives a brief analysis of the source of the high-temperature steam, cooling water, compressed air source, mold temperature control systems, injection molding machine and mold and process monitoring system.As the research object shell, Hisense LCD TLM46V69 RHCM in front of the television combines characteristics of RHCM injection molding process, then received the modeling techniques of injection molding process of its finite element analysis. In light of the actual production situation and the theoretical analysis and calculation, this paper calculated LCD TV TLM46V69 RHCM shell RHCM injection mold heating / cooling layout, pipe diameter, etc. So that it determined Heat exchange coefficient between the heating / cooling medium and molds in this analysis, then established the three-dimensional flow model which coincides with True plastic melt flow behavior.Simulation gived the law that melt temperature, mold temperature, packing pressure, packing time, injection time, cooling time such process parameters on the high optical quality of plastic parts, which is received according to the results of the analysis such as pressure, temperature, location of weld marks, warpage, internal stress. The study found RHCM injection process maintain a high mold temperature in the injection and holding pressure phase, lower melt viscosity, which enable the plastic forming process of fusion in a state of complete fusion weld without trace, and reduce the flow impedance at the time of filling, reduce pressure loss and the amount of warpage of the parts. Moreover, Molding RHCM, small injection Pressure and Internal stress of plastic parts after cooling, decreased Shear stress and shear rate, which improved melt flow behavior, so that to improve crystallinity and a more uniform structure of Plastic parts, then improve the surface hardness of plastic parts.Simulation determined the effects of injection molding process RHCM six major parameters: melt temperature, mold temperature, injection pressure, injection time, packing time, packing pressure. And it Selected the five levels for each parameter, then designed orthogonal test table. Simulation has been received the Level of importance of the impact that amount of process parameters on the warpage as follows: pressure pressure> pressure time> cooling time> injection pressure> melt temperature> mold temperature. After Analysis, it gives the optimal combination of technology, that is, when the melt temperature of 236℃, mold temperature of 110℃, injection time of 3.5s, the time pressure for the 20s, the cooling time of 50s, packing pressure 80%, Warpage of Plastic minimum, which is contributed to design and manufacture of flat-panel TV production mold. The best options which helps to develop the production process parameters and process card, addition to the test mode Production has been happened on then HTF1500X Haitian injection molding machine, which have been contributed to pre-qualified TV Highlight shell plastic parts, then verified the correctness of the optimization analysis program in this paper.In the basis of the numerical simulation of Rapid thermal cycling in injection molding and Parameter Optimization, this paper makes a heat balance analysis of Hot Runner which is used in the mold. According to the heating style of the hot runner system and relevant parameters of heating elements of the RHCM injection mold, the simulation established Three-dimensional thermomechanical coupled finite element analysis model of two key components of the hot runner, that is, the root plate and the nozzle flow. Furthermore, this paper analyzed the temperature field and deformation field in the heating process of this model. According to temperature distribution and deformation, the model optimized the heating elements layout of the root plate and the nozzle flow, which helped to reach the basic uniform of its temperature distribution and deformation, and the distribution was symmetrical.