Research On Injection Molding Processing Of Automobile Rear Bumper Based On Needle Valve Technology And Response Surface Method

Injection molding has become one of the most important methods of plastic molding processing, but this process is a result of dynamic coupling of multiple factors, there will be many defects. As the increasing development of science and economy, people have higher request for products. Especially for the large panel products like car bumper, because of the strip large surface characteristics of the product, molding defects are weld lines on the main surface and the warping deformation in the actual production. How to improve and avoid these defects becomes a problem that engineers must solve. In the traditional design and manufacture mode, design personnel mainly depend on experience to to debug and modify, also spend a lot of time,unable to predict the warpage of plastic parts, welding wire etc.. Due to the structure, injection molding machine, material type, mold and so on have been identified before the start of injection molding production, so changing the process to eliminate the defects become the economic and feasible method.For the weld line occurring on the surface of the rear bumper that product by Automotive Components Company in Jiangxi, established an accurate and reliable CAE analysis model based on the analysis and summary of weld lines and how to control, and calculate the runner system size under the guidance of therheology principle and formula, using needle type casting technology design eight different gating scheme, the molding process was simulated by the CAE analysis software. According to the simulation results, comparing the important results like maximum clamping force, maximum injection pressure, maximum warpage, weld line of different schemes, choosing the optimum gating system scheme.Taking the amount of warpage of the car rear bumper as the optimization goal, the mold temperature, melt temperature, injection time, packing time and packing pressure as the optimization variables. According to the design principle of BBD response surface method to establish the predictive regression model of warpage on the five factors. Analysis of variance technique was applied to check the fitting degree of the predictive model and effects of various process parameters on the warpage deformation. Then the effects of various parameters on the warpage was not a simple linear relationship, but was a strong nonlinear coupling. The mold temperature and melt temperature impacted very significantly on the warpage of products among the five factors, followed by the packing pressure, packing time, injection time.Using the particle swarm optimization algorithm and the Latin hypercube sampling method to design experiment, taking mold temperature and melt temperature that influence the amount of warpage extremely remarkable as the design variables, optimization objective is the minimize amount of warpage, the program was written in Matlab, and finally get the optimization process parameters. The result is providing methods and approaches for selection of process parameters in injection molding of the car rear bumper.