Research On Two Axis Flexible Roll Bending Technology For Non-circular Section Parts

Compared with the three-axle or four-axle roll bending,two-axle flexible roll forming technology has many advantages such as small straight edge,good surface quality,high forming efficiency and smaller forming radius.It has been widely applied in aeronautics and astronautics,ship and automobile,petrochemical industry,food and medical fields.However,the two-axle flexible roll forming technology is only applied to the bending of single circular section parts.Three-axle or four-axle roll bending noncircular parts with low accuracy,so it can not meet the requirement of forming such as automobile exhaust pipe and aircraft leading edge covering and so on.Developing two-axle flexible roll forming technology for noncircular section parts can improve the production efficiency and forming accuracy of noncircular section parts,and achieve the forming of aircraft leading edge covering parts.Based on two axis flexible roll bending theory,composite Simpson theory,finite element analysis method and flexible roll synchronization control technology,two-axle flexible roll forming of noncircular section parts has been realized.The main research work of this paper is as follows:(1)Based on the elastic-plastic theory and Hertz theory,analyse the mechanical state of the two axis flexible roll bending process,and combined with the compound Simpson theory,deduced the press-in amount adjustment model of the two axle flexible roll forming for the noncircular section parts.(2)According to the flexible roller synchronous precision of the existing two-axle bending machine is low,develop a double closed loop fuzzy PID synchronous controller for flexible roll hydraulic lifting.By using AMESim/Simulink joint simulation,compare and analyze the synchronous control performance of PID control,fuzzy PID control and double closed loop fuzzy PID control.The results show that the double closed loop fuzzy PID synchronization control is better and has good robustness.(3)Carry out the roll forming test of 2024-T351 aluminum alloy sheet,and analyse the influence of press-in amount on the curvature radius of sheet metal.A roll bending model of noncircular section parts is established,and roll bending tests of elliptical section parts with different specifications are carried out,and obtain a satisfactory accuracy result.(4)Use ABAQUS software to establish the two-axle flexible roll forming finite element model for noncircular section parts.Simulate different types of elliptical cross section parts bending process,and the difference between the theoretical value and the theoretical value is small.The reliability of the finite element model of two-axle flexible roll bending with noncircular section is verified,which provides theoretical and data reference for the forming of noncircular section parts such as aircraft leading edge covering.