Technique Analysis And Optimization Of X-joints Hydroforming Process Finite Element Simulation

On the premise of ensuring the quality of automobile parts, reducing the weightof components is one of the trends of the advanced manufacturing technologydevelopment in the fields of aerospace and automobile industry etc. The inner highpressure forming is one kind of advanced manufacturing technologies which takelightweight as the core in this demand. Compared with the traditional processmachining, casting, forging and welding technology，the quality of hydroformingproducts are high and the thickness distribution is uniform. This technology has beenthe forefront and hot point in plastic working field.This paper had analyzed the effect of die radius, inner pressure extrusion punchaxial feed, balance punch feed, friction coefficient on inner high pressure forming ofX joints by dynaform finite element simulation software. The results showed that dieradius should be as large as possible under satisfying of the X joints quality. Thispaper also analyzed the effect of bilinear, gradient and three linear internal pressureloading paths on the results of hydroforming, respectively. And three linear internalpressure loading path was adopted finally. The main feeding stage of the axialfeeding should be in the forming stage, while the feed rate should be reduced or bezero in the shaping stage. To make the pipe be shaped under a good compressivestress, the balanced punch should try to keep in contact with the branch pipe on thetop in the feed forming process.For the optimization of internal high pressure forming parameters, combining ofthe finite element simulation software and the response surface method to optimizethe parameters was presented in this paper. The initial feeding amount, initial internalpressure and the middle pressure were selected as the design variables, the minimumand maximum wall thickness after forming were selected as the design goals. Basedon the Box-Behnken design and response surface method, the response surfacemodel was built respectively. The optimal parameters of the model were determinedthrough the analysis of variance and regression. The error rate that the factor value predicted by dynaform finite element simulation compared with the value obtainedby the model was less than1%, which verifying the reliability of the model.