Research On The Aluminum Alloy Automobile Outdoor Forming By Hydrodynamic Deep Drawing Adopting Variable Blank Holder Force Based On Numerical Simulation

Recently, in order to reduce the weight of automobile body, reduce gasconsumption and emission, aluminum alloy, as a kind of light-weight materials hasbeen extensively applied into the stamping of automobile panel. However, as thecomplicate shape and huge dimension of the automobile panels, and the lowformability of aluminum alloy, the common process of aluminum alloy automobilepanel may always lead to many quality problems, such as wrinkle and crack and soon.As a kind of advanced forming technique, hydro forming adopts fluid mediumbut not die to transfer load. Compared with the traditional deep drawing process, ithas a lot of good qualities, such as simple structure, low cost and high formingprecision. Variable blank-holder force can change the size of the blank-holder forcewith the position or by punch stroke in sheet stamping forming process. Thetraditional constant blank-holder force only role in the thickest point, variableblank-holder force can reasonable control the flow of sheet, enhance the stability inthe deep drawing process, and reduce the fluctuate of the size of the forming parts.This article implemented the aluminum alloy automotive outdoor, using the newprocess by Hydro forming combined with variable blank-holder force, establishingthe sheet metal forming finite-element model of the aluminum alloy automotiveoutdoor by using DYNAFORM5.7, adopt the method of orthogonal experimentdesign to analysis the main influence factors, including blank holder force, velocityof stamping, die clearance and friction coefficient, and find the optimal combinationof the four factors. Research on the overall variable blank holder and hydro formingof the automobile outdoor, obtain the reasonable chamber pressure loading curve andvariable blank-holder force loading curve. And the divided mode of the blank holder and the combining form of the blank holder force have been studied.The influence of the common drawing process and the new technology onautomobile outdoor forming quality and procedure was investigated and analyzed bytaking the thickness distribution, Forming Limit Diagrams (FLD), and the thinningrate as standard. Simulation results show that, formed parts by new technology,compared with common drawing process, the thickness thinning quantity is smaller,forming precision and uniformity of the thickness distribution has greatly improved.