Exploration On IHTC And Influence Factors Of AA5083 In Elevated Temperature Forming Process

Energy saving, environmental protection and safety are the main subjects of the current development of automobile industry. Automobile lightweight has become the main trend in the automobile industry. The application of aluminum alloy as the body panel material is one of the major measures to achieve the car lightweight. Right now aluminum alloy is applied on body panels increasingly common.At room temperature, aluminum alloy has relatively low plasticity and poor formability, also the surfaces of parts are easy to form defects, and lack of dimensional accuracy. Aluminum alloy elevated temperature forming is to do stamping after the sheet is heated to a higher temperature, improving the material formability and product dimensional accuracy. In the elevated temperature forming process, heat transfer coefficient between the sheet and mold is an important boundary condition in the elevated temperature forming numerical simulation. An accurate interfacial heat transfer coefficient is of great significance for precisely simulating product mechanical properties, microstructure and forming quality.Considering the characteristics of aluminum alloy elevated temperature forming, circular heat transfer test model is constructed, utilizing Beck’s non-linear estimation method to calculate interfacial heat transfer coefficient. Applying the calculated heat transfer coefficient curve in DEFORM finite element analysis software to do simulation, the simulated temperature values are of high agreement with the experimental measured temperature values, with an error of 4.0% by Beck’s non-linear estimation method and 3.2% by combination of heat balance method and Beck’s non-linear estimation method, proving the reliability of Beck’s non-linear estimation method.Utilizing Beck’s non-linear estimation method, the influence of stamping load, interface temperature, interface medium and physical properties of material on the interfacial heat transfer coefficient is researched in this paper. The research result shows that:1) If the stamping load increases, the deformation degree of micro-bulge on the contact surface will increase, the real contact surface area will increase, so the interfacial heat transfer coefficient increases. The interfacial heat transfer coefficient on stamping load shows a power exponential function; 2) Under the same stamping load, the temperature rise will reduce the hardness of the material, so the deformation degree of micro-bulge increases, mutual diffusion phenomenon may occur between materials, interface contact becomes better, the heat transfer coefficient increases; 3) The interface heat transfer intensity will decrease when the filled material is of low thermal conductivity and large thickness. For dual-contact interface heat exchange, filling one contact interface with thermal insulating material will increase the heat transfer intensity of the other contact interface, making the material cooling effect more obvious; 4) Change the mold material to study the influence of material physical properties on the heat transfer coefficient. The result shows that,45# mold steel with higher thermal conductivity has a higher heat transfer coefficient than H13 mold steel.