Crack Analysis And Optimal Control Of Plastic Parts Of Bracket In Automobile Bumper

With the introduction of lightweight concepts,more and more automotive structural parts have begun to use injection molded parts.Since most of the automobile structural parts are installed inside the automobile in actual use,they only need to have enough mechanical properties to meet the requirements of use,and the apparent quality is not high,except for parts with high precision.Therefore,in order to make up for the lack of strength of traditional plastics,fibers such as glass fibers are often added for reinforcement.In the actual production process,automotive injection molded structural parts often have some problems,such as cracking,warping and so on.Therefore,this article mainly focuses on the cracking phenomenon of automobile injection molded structural parts,and studies its mechanism and optimizes it to improve the qualified rate of products.The injection molded parts of this subject come from the middle bracket of the car bumper produced by a certain company.Through the analysis of its cracking mechanism,it is confirmed that it is due to the existence of weld marks and residual stress.Through the ANSYS statics simulation of the actual assembly process,the mesh refinement of the stress concentration area,the application of constraints and the application of pressure loads according to the assembly sequence,from the simulation data results,we can see that: The largest is the most prone to cracking.Using MOLDFLOW software to optimize the gating system of the hot runner mold,two gating schemes are proposed,and the 4-gate scheme of the fan gate is found to be the best through simulation.At the same time,optimization of the cooling system of the hot runner mold has been carried out.The simulation comparison analysis of the original scheme,the traditional improvement scheme and the three schemes of the near conformal water circuit shows that the near conformal water circuit has the best cooling effect.Then combined with the results of ANSYS,using MOLDFLOW to predict and analyze its weld line and residual stress,using a combination of response surface and genetic algorithm,the optimal parameter set was obtained,and finally verified by simulation,the result was close to the optimization result.