Research On The Rotation Bending Processing Of AZ61Magnesium Alloy Tube

Bent tube, as an important component, which can meet the requirement of light weight and high strength in the aspect of material and structure, has obtained extensive applications in the aerospace, marine, automotive, medical and health care and other high-end industries. Tube bending forming technology is one of the key technologies of lightweight products forming, and the rotary draw bending has become an important research technology in the field of tube bending forming on account of its unique advantages. People in the past emphasized on the research of steel and aluminum alloy tubes. However, with the development of industrial lightweight, they were gradually replaced by the magnesium alloy tube, which becomes the main research object in tube bending process.The magnesium alloy not only has the advantages of low density which is only about 1/4 of steel, light weight, high specific strength and stiffness and so on, but also possesses merits of quick heat dissipation, high heat resistance and recycling. Therefore,it is widely used in the manufacturing of vehicle body structure parts of aerospace and rail vehicles. Meanwhile, it is also an important material for the lightweight of car body.However, magnesium alloy has poor ductility at room temperature, which limits its application, making its potential far from full play. Most research scholars have set the research on magnesium alloy at high temperature, but the plastic deformation at room temperature is rarely studied. Although the plasticity of magnesium alloy has been improved at high temperature, the high temperature forming will increase the complexity of the deformation, and the high heating temperature is not conducive to thebending forming of magnesium alloy tubes. In view of this, this article obtained the curve and of mechanical properties and analyzed fracture mode of AZ61 magnesium alloy at the room temperature through the tensile and compression experiments. Then,these parameters are applied to the simulation of rotary draw bending. Finally, the simulation results are verified by experiments. The conclusions are as follows:(1) when the tube bending radius R=120 mm, within the scope of 0 ° ~ 180 °, the wall thickness thinning rate of the bent tube is increased with the increase of the bending angle. In order to reach the maximum value of about 75°, when the bending angle continues to increase, then the two basically unchanged. The trend of the maximum ovality of the cross section of tube is similar to the tube. However, after reaching the maximum value, while the bending angle increases, the ellipse has a slight downward trend, which is opposite to the springback rate. The value of the springback rate is inversely proportional to the bending angle, and it decreases with the increase of bending angles.(2) when the tube bending angle α = 90°and bending radius is between 90 ~ 150 mm,the wall thickness thinning rate of the bent tube is decreased with the increase of the bending radius, which is consistent with the trend of the maximum ovality but opposite to the variation trend of springback rate. Specifically, when the bending radius is increased, the springback rate increases.