Optimization Design Of Viable Blank Holder Force And Forming Performance Simulation Oriented To Stretching Hydraulic Press And Its Applications

Hydraulic equipment is the strategic pillar industry in our country and the foundation of many important projects. With the development of new material as high temperature alloy and titanium alloy, welding processing technology of large size and high-strength thin-walled member had become the bottleneck of aerospace product forming quality. It was necessary to develop a large-scale deep drawing hydraulic equipment to meet the requirements of integrated, lightweight and high reliability aerospace products. In order to solve the problems:springback after thin-walled member deep drawing, springback angle of thin-walled member during the optimization of variable blank holder force was difficult to measure and the stress distribution of blank holder force was simplified during forming performance simulation, the modeling method of hydraulic equipment thin-walled member deep drawing forming, the optimization method of variable blank holder force, and the performance parameters design method of deep drawing forming device was intensive studied, optimization design of VBHF and forming performance simulation oriented to stretching hydraulic press was put forward. It was applied in the design and development of the deep drawing device of HFM150MN hydraulic press.The main contents of this thesis were summarized as follows:In the first chapter, the present statuses of the thin-walled member deep drawing forming technology were summarized. The present researches of sheet metal stretching forming model, optimization design of process parameter, forming performance simulation were discussed. The problems were described. The main contents and the organization framework of this dissertation were presented.In the second chapter, modeling method of thin-walled member deep drawing based on springback controlling was proposed. The influence mechanism of spring back on forming precision was analyzed, and numerical model of spring back of sheet metal forming was built using the average bending of sheet metal to measure spring back. The influencing rule of deep drawing forming parameters on springback was revealed, and the theoretical basis for optimizing BHF curve reasonably was provided.In the third chapter, the optimization of VBHF in sheet forming deep drawing based on Kriging-NSGAII was proposed. According to the analysis of the performance index which influenced the forming quality of thin-walled member deep drawing, multi-objective optimization model of thin-walled member deep drawing was built, the approximate model of Kriging was established oriented to the symmetric Latin hypercube design, the approximate model was proposed using NSGA-Ⅱ genetic algorithm, and the solution set was preferred through the fuzzy set pair theory to obtain the optimal design parameters. The deep drawing of a head drawing piece was studied as an example to verify the feasibility of the optimization method.In the fourth chapter, the forming performance simulation analysis technology of deep drawing device of hydraulic equipment based on grey relation entropy was put forward. The structure parameters which influence on the formability of deep drawing were simulated, the grey correlation of structure parameters of the deep drawing device was analyzed based on the theory of grey correlation entropy to obtain the structure parameters of deep drawing device possessing the best forming performance.150MN double action drawing hydraulic press of HFM was studied as an example to analyze of structural parameters possessing the best forming performance, and then the stretching device model was establish.In the fifth chapter, functional modules of parameters optimization design system of sheet metal deep drawing oriented to hydraulic equipment was developed combined with the enterprise project, which was applied in the enterprise to verify the feasibility and the effectiveness of the technique and system mentioned above.In the sixth chapter the research contents of the whole dissertation were summarized, and the further research direction was prospected.