Numeric Simulation And Process Optimization For Gas Assisted Injection Molding Of Sundries-Box

Gas Assisted Injection Molding (GAM) is modern plastic molding technology, which was developed on the basis of the traditional injection technology. In GAM, first the mold cavity is partially or completely filled by the polymer melt, next the core of the polymer melt is injected by the high pressure inertia gas through the runner or any designed gas channel in the mold cavity to force the melt into flowing continuatively and filling the cavity, finally under the packing pressure of the gas the polymer melt cools down and solidifies to produce the hollow or void part There are the many advantages in GAM, but GAM process and its product quality control become more critical and difficult since additional process-parameters are involved, including melt pre-injecting amount, gas injecting delay time, gas pressure and gas packing time.At present, the gas channel distributions of GAM products mostly are normal, symmetrical or adequate, little relate to the typical structure product which gas channel is fully located at one side. So an exigent demand is put forward for researching GAM characteristic of the typical structure product. By means of CAE technology, the effects of process variables on product molding quality are analyzed so as to help technologists draw up the correct GAM process plan, help mold designers improve and optimize mold structure.In this thesis, making used of orthogonal experiment method and MoldflowPlastics Insight?, the GAM process of a sundries box in Fukang car was researched under the different molding conditions. Through analyzing synthetically the experiment data, the rules were found which the GAM process parameters influenced the sundries box qualities such as sink mark depth, the gas channel minimum thickness, the maximum warpage and so on. Based on the research results, an optimum process plan for molding the sundries box was drown up.According to correlative literatures, GAM had an advantage in reducing the product wrapage. But to the typical products which gas channel are fully located at one side of structure, such as the sundries box, the conclusion must not right It is necessary to adopt other effective assistant measure to reduce or control wrapage.The research shows that melt temperature, melt pre-injecting amount, gas delay time and gas packing pressure are the four important processing parameters to impact on the sundries box quality. The GAM parameters which affect evidently the sink mark depth at the rib root of sundries box are melt temperature and melt pre-injecting amount, which the minimum thickness of gas channel are melt temperature and gas delay time, which the maximum warpage are gas packing pressure and melt temperature.The optimum processing parameters of the sundries box in GAM were got by the numerical simulation experiments, those were mold temperature 35 °C, melt temperature 205 "C, melt pre-injection amount 100%, overflow well open at 7s and close at 40s, gas delay time 7s, gas pressure 24MPa and cool time 60s.