| Titanium alloy space structural parts have high strength,low density and corrosion resistance.As a light alloy,they are widely used as lightweight skeleton materials for highend equipment such as aircraft,automobiles and railway vehicle.However,titanium alloy is difficult to be formed at room temperature,so it is usually processed by electric current assisted heating.Titanium alloy material at high temperature has the characteristics of superplasticity,which can effectively reduce the occurrence of springback deformation.Therefore,in order to realize the TC4 titanium alloy profile space complex multidimensional structure of bending forming,this paper based on the heat stretch bending forming and multipoint stretch bending forming technology,this paper proposes a multi-point threedimensional hot stretch bending forming process,optimized the multi-point die,by TC4three-dimensional thermal bending test,the establishment of the analytical model of springback numerical simulation and theory.The influence of process parameters on springback deformation was predicted and quantified.Details are as follows:Firstly,the high temperature tensile test of TC4 titanium alloy was carried out to analyze the rheological behavior of titanium alloy at different temperatures of 500?,600? and700?,and the constitutive relationship was fitted according to the stress-strain curve,which provided a theoretical basis for the subsequent three-dimensional numerical simulation of hot stretching and bending of titanium alloy and analytical model of theoretical rebound.The validity of the process was verified by hot stretching and bending experiments on L section and rectangular section under different working conditions,and the influence of different process parameters on TC4 titanium alloy 3D hot forming was obtained.Secondly,based on ABAQUS software,based on the multi-point three-dimensional hot stretch bending forming technology has established the numerical simulation model of TC4 titanium alloy L section,and a model is established with the model,two kinds of the forming results of numerical simulation model and the springback results and the test result is slightly different,but,half a model of computing time is about half the whole model,Therefore,the subsequent numerical simulation model was analyzed by the semi-model.Through the numerical simulation of the semi-model,the experimental results of L section and rectangular section under different pre-tensile conditions were compared and analyzed,and the prediction accuracy was within 20%,which further verified the effectiveness of the model.Finally,two analytical models of theoretical springback were established by analyzing the variation of stress and strain distribution in cross section of TC4 titanium alloy profile during 3D hot stretch bending.They are the theoretical model of The Triangle bend based on plane deformation hypothesis and the theoretical model of the triangle bend considering deformation superposition process.The validity of the theoretical model was verified by the L section of titanium alloy.Finally,the trivilla bending of TC4 titanium alloy was predicted successfully.In this paper,the three-dimensional hot stretch bending process of TC4 titanium alloy was tested and analyzed by numerical simulation model,and the influence law of different process parameters on the final forming results was obtained.By establishing numerical simulation model and theoretical springback analytical model,the springback results of three dimensional hot stretch bending of TC4 titanium alloy were successfully predicted.It provides a theoretical reference for the subsequent research on TC4 titanium alloy 3D hot stretch bending. |
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