Simulation Analysis And Process Parameters Optimization In Forming Of Engine Heat Shield

As for the heat shield of the automotive engine which is stamped by the thin steel plate with hot dip aluminum, its shape is quite complex as well as the unreasonable system design of mould and process parameter setting, and these problems are more likely to lead to some forming defects about the heat shield, such as wrinkling, cracking, and forming inadequate, etc. Since there are quite complex nonlinear changes in the forming process of heat shield, process parameters would be the main factors that influence the forming quality of heat shield after designing the reasonable mould system. In order to improve the forming quality of the heat shield, the optimization of process parameters has huge important significance and practical value.With the rapid development and gradual maturity of simulation technology, the mature commercial software, such as Dynaform, provides a very useful help for the parameters optimization of sheet metal stamping process. Therefore, an experimental analysis is conducted on the engine cover sample which is produced by an automobile accessories factory, and some problems are found in this paper, such as excessive thinning which are caused by the unreasonable setting of process parameters. On this basis, through the comparative analysis with experimental results, the accurate simulation analysis model of the heat shield was built by using Dynaform software, and the effects of process parameters on the quality of the heat shield forming are analyzed by using this simulation model and choosing stamping speed, blank holder force, drawing coefficient, friction coefficient and mold gap as optimization variables.In order to carry out the parameters optimization of heat shield in the stamping process, according to the FLD and reduction ratio figure, drawbacks like wrinkling and cracking of the heat shield can be effectively evaluated. This paper defines the maximum rate of thinning and wrinkling as two evaluation indexes, then it constructs the objective function and establishes the mathematical model of the process parameters optimization based on this.First of all, this paper uses the orthogonal experiment to carry out the parameters optimization of the heat shield, and chooses maximum thinning rate, wrinkling rate and weighted combination to build the objective function, then it uses the range analysis method to optimize the process parameters of the heat shield. The optimization result shows that better optimal parameters of the heat shield could be obtained and maximum thinning rate and wrinkling rate could be controlled in a good range by the weighted objective function, and the forming quality could be improved as well. But it is difficult for a single evaluation index to achieve these goals.Due to the lack of various factors’ level in the orthogonal experiment, this paper uses the uniform design and regression analysis method to analysis the process parameters optimization of the heat shield. Through the quadratic polynomial regression model of the process parameters and weighted objective function, the best optimal solution could be obtained. The optimization result shows that better optimal parameters of the heat shield could be obtained and maximum thinning rate and wrinkling rate could be controlled in a good range by the weighted objective function, and the forming quality could be improved as well.Because of the reasonable experiment design of the response surface method, the response surface function is widely used in the process parameters optimization. Therefore, this article used the BBD design and response surface method to establish the quadratic polynomial response surface model on the process parameters with maximum thinning rate and wrinkling rate, and optimized them. Weighted maximum thinning rate and wrinkle rate optimization model as the objective function optimized process parameters, the maximum thinning rate and wrinkling rate can be under better control.