Research On The Product Development And Plastic Injection Molding Process For The Safety Case

Plastic safety protection case (hereinafter referred to safety case) is a high-gradepackage, currently has been widely utilized in industrial, military, fire fighting,photography and scientific exploration and other fields. But there is a big gapbetween the domestic safety cases and the foreigner ones in the aspects of materials,structure design and injection molding process. It is important to study on thematerials, structure design and plastic injection molding process of the safety case.The functional requirements, usability and forming property of safety case istaken as the starting point, and then chosen polypropylene as the raw material. Thematerial modification experiment is finished by filling modification method, in orderto improve the mechanical properties of the safety case. The results show that theproperties are better than similar domestic products significantly and close to theimport products, it is preferred to meet the requirements of production and usability.According to the structure design principle of plastic parts and the structure andforming characteristics of the safety case, completed the design of a safety case; thedrop simulation is performed to verify design reliability of safety case based on thesoft Hypermesh, ANSYS/LS-DYNA and LS-PREPOST.Selected bottom (the largest and the most complex part of the safety case) as theresearch object. The numerical simulation analysis model of safety case is finished bythe software AMI; Token the medium temperature and the pipe temperature as targetto establish the cooling system of the safety case injection molding, and emphaticallyresearch the optimization design of the gating system according to the number,distribution and control of the valve gate.The orthogonal experimental design and numerical simulation is performed byusing the process parameters such as mold temperature, melt temperature, injectionrate, packing pressure and packing time, with the greatest sink index and themaximum warpage as the optimization objective. The results reveal the effect regularand significantly of each process parameters on safety case molding. The degree ofinfluence on the maximum sink index as follows: melt temperature, packing time,injection rate, packing pressure and mold temperature; the degree of influence on themaximum warpage as follows: melt temperature, packing time, packing pressure, injection rate and mold temperature.Take the orthogonal test results as the experimental sample, based on theparameter optimization software Isight, a response surface approximation model isfinished to establish the relationship between the process parameters and the moldingquality, then optimization the process parameters with Non-dominated SortingGenetic Algorithm, and finally obtain a set of optimal process parameters. The resultsof simulation analysis showed that: the relationship between injection moldingprocess parameters and multi-objection can be established by taking response surfacemodel into injection molding process optimization, using non-dominated sortinggenetic algorithm to obtain the optimal process parameters on the response surfacemodel, the injection molding process was optimized quickly and efficiently byutilizing this optimization method, and the simulation results are coincide to the testresults.