Research On Bending And Unbending Device And Process Of Sheet Metal

With the in-depth study of the mechanical properties of metal materials,many scholars believe that the main process of repeated bending forming,such as roll forming,in the finite element simulation,the material parameters obtained only by tensile test can not accurately describe the material forming process,and the pure bending and unbending experiments can more accurately reflect the mechanical properties of materials.In this paper,a pure bending and unbending device is designed to obtain the bending moment-curvature data of sheet metal during bending deformation.Firstly,the pure bending principle is analyzed,and the path of the left and right clamps is designed.And the mechanical structure part of the parts design and overall assembly,check and calculate the thread,tension arm connecting shaft and other core parts.By rotating the left and right extension arms and the torque sensor shaft,the device compensates the movement of the fixture to make the fixture of the fixed specimen rotate and move,and the bending and unbending of the specimen is controlled by the forward and reverse rotation of the motor.Secondly,a motion control system is developed based on Beckhoff PLC and servo controller,and the electrical wiring diagram of the whole system is designed.The relationship between the bending angle of the specimen and the Y-speed of the compensation motor is calculated through the path trajectory,and then the servo and EL2521(high speed pulse module)parameters are set to make the motor test run.The encoder signal is collected by EL5101(encoder acquisition module)and converted into the bending angle variable of the test piece in PLC programming design.In Twin Cat3,St language is used to program and design HMI,and Twin Cat scope view is used to record bending moment-curvature data.Finally,the device is tested and the bending test is done.The curvature-time,moment-time and moment-curvature curve are recorded.The high accuracy of curvature time curve indicates that the compensation motion of motor X and motor Y is relatively stable,and the signal acquisition accuracy of EL5101 is also high.The smoothness of moment-time and moment-curvature curves is relatively low,and FIR(finite length unit impulse response filter)and IIR(recursive filter)are added to the system to optimize the data acquisition accuracy of torque sensor.The results show that the moment-curvature curve accuracy is relatively high by adding FIR50 Hz filter to the system.