| With the sharp increase in the number of cars held and the enhancement of energy conservation and environmental protection awareness,the trend towards lightweight in the automotive industry is in line with the trend of the times.In order to reduce the weight of cars,using plastic instead of metal in car parts is currently the most commonly used way for most car manufacturers to reduce weight.However,plastic automotive components may have injection molding defects during the molding process,which can greatly affect the performance of the components.For the air intake system of a car,the injection molding defects of the intake manifold(manifold)will affect the air intake performance and reduce the fuel efficiency of the engine.Therefore,analyzing the impact of manifold injection molding defects on intake performance and optimizing the production process of the manifold through numerical simulation to improve intake performance has theoretical research value and practical significance for engineering applications.Taking the manifold of a certain vehicle model as the research object,this study explores the impact of manifold injection molding defects on intake performance,and optimizes it from the perspective of injection molding process parameters.Firstly,analyze the injection molding process of the manifold,establish a pouring and cooling system,and verify the rationality of its design;Secondly,the impact of welding marks,air pockets,and warping deformation on the intake performance of the manifold was analyzed,and the intake flow deviation rate and non-uniformity were used as evaluation indicators.The pressure,speed,and flow rate of the manifold were analyzed through the joint simulation of Moldflow and Ansys.It was found that warping deformation had the greatest impact on the intake performance,while welding marks and air pockets had a smaller impact on it;Once again,with the goal of optimizing warping deformation,the temperature,time,and pressure factors that have the most important impact on manifold injection molding were selected.Five factors,namely melt temperature,mold temperature,cooling time,holding time,and holding pressure,were initially proposed.Through single factor experiments,it was found that the cooling time did not have a significant impact on the warping deformation of the manifold.Orthogonal experiments were designed to rank the significance of each factor;In order to minimize the warpage of the manifold,response surface experiments were designed to analyze the degree of interaction of various factors,and a random forest regression model was established.With 29 groups of data from the response surface experiments as the original samples,a regression decision tree was constructed.Then,based on Bootstrap sampling,through the prediction of random forest algorithm,the process parameter combination with the smallest warpage was obtained.Through simulation,the manifold warpage deformation was 1.032 mm,Compared with the 1.416 mm before optimization,it decreased by 27.1%;Finally,simulation analysis was conducted on the optimized manifold,and it was found that the average pressure difference of the manifold decreased by 0.5KPa,and the uniformity of speed slightly improved.The range of flow deviation rate and unevenness decreased from the original [-3.944%,3.554%] and 7.50% to [-2.545%,1.698%] and4.24%,respectively.The results showed that the intake performance was improved by optimizing the injection molding warping deformation of the manifold. |
