Study On Forming Technology Of Small Curvature Titanium Alloy Plate And Strip Based On Self-resistive Heating

Small curvature titanium alloy strip has a large market demand in aerospace and other fields.However,due to the large springback in the bending process at room temperature,the bending accuracy of the molded parts is difficult to guarantee.In order to solve the problem of poor forming performance at room temperature,and the traditional hot forming process of mold heating causes energy waste,high processing cost and low forming efficiency.In this paper,taking TC4 titanium alloy strip as the research object,combined with the characteristics of titanium alloy with high resistivity and high melting point,the hot forming process was studied by self-resistance heating.Preesent paper has been carried out as follows.(1)The Joule heat generated by self-resistance heating of plate and strip is analyzed,and the theoretical model of temperature rise of self-resistance heating is established.Aiming at the heat dissipation problem in the heating process,the comprehensive heat dissipation coefficient is proposed and determined.According to the characteristics of small curvature plastic bending,the influence of temperature and aging time on springback is analyzed,and the theoretical model of springback calculation for hot bending based on self-resistance heating is established.(2)The mechanical tensile test of TC4 sheet under different temperature conditions was carried out to clarify the influence of temperature on the mechanical parameters of titanium alloy;The stress relaxation experiment at high temperature was carried out,and the binary stress attenuation function of stress value changing with temperature and time was obtained by combining the experimental data.(3)The self-resistance heating experimental platform of TC4 titanium alloy was designed and built.The temperature rise experiment of self-resistance heating was carried out with TC4 titanium alloy plate as raw material,and the actual temperature rise efficiency of self-resistance heating was determined.Combined with the experimental data,the specific value of the comprehensive heat dissipation coefficient in the theoretical model of temperature rise is determined.(4)ABAQUS finite element analysis software was used to simulate the electric-thermal coupling finite element temperature field of profiles with different cross-section sizes.Combined with the forming process,the electric-thermal-solid coupling finite element simulation of the mold and plate was carried out,and the temperature field distribution of the mold and plate after bending was obtained.(5)The bending forming process experiment platform based on self-resistance heating was designed and built,and the bending experiments under different curvatures,temperatures and holding times were carried out.The experimental results are compared with the calculated values of the target curvature radius and the theoretical model to verify the feasibility of the forming scheme.