Design Of Control System Of Sheet Metal Bending Test Device

Sheet metal testing technology is important for obtaining mechanical performance parameters.Research shows that bending testing can better reflect the mechanical behavior of sheet metal during bending compared with tensile testing.Therefore,developing a metal sheet bending test device and control system is crucial.This paper focuses on studying the control system design of the metal sheet bending test device invented by the research group.The main work is to investigate and develop the control system of the device:(1)Firstly,based on the bending deformation principle of the plate,the kinematic equation of the device during bending test was derived,and the loading force range of DP980 plate during bending was calculated through the force analysis.Then,Lagrange method is used to establish the dynamic equation of the device.Finally,the rigid-flexible coupling model of the device was built in ADAMS software,and the loading torque was taken as the interference factor for simulation analysis.The results verify the correctness of the equation of motion.Under a given load,the theoretical value of the output torque of the motor at the active end is consistent with the simulated value,and the deformation of the flexible body is less than the allowable deflection,indicating that the device meets the requirements of bending test.(2)To address the issue of low motion accuracy in the device caused by nonlinear factors,a nonlinear controller was designed.The simulation model of the device was built using ADAMS-MATLAB to further adjust the parameters of the controller.Meanwhile,the performance of the controller was compared with that of the traditional PID control method.The results showed that the maximum overshoot was reduced by 23.3%,and the settling time was reduced by 43.3s,satisfying the control requirements of the system.(3)To achieve the requirements of high precision and scalability of the control system,a control system plan for the device was developed.Based on this plan,the configuration of the system hardware structure,the programming of software programs,and the interaction interface programs were completed.The designed fuzzy PID control algorithm was embedded in the main program to verify the control effect of the algorithm on the Twin CAT platform.Finally,a metal sheet bending test device control system with position closed-loop control was integrated.(4)To verify the reliability and effectiveness of the control system,experiments were conducted to test the control performance and the effectiveness of the fuzzy PID direct closed-loop control effect test were carried out,and the motion accuracy and bending motion test were carried out respectively.The results show that the motion accuracy meets the design index,and the controller error is within ±0.005°,which meets the design requirements and reduces the interference of axial force on the bending process of sheet metal.(5)A mechanical property study was carried out on high-strength steel DP980,and a metal sheet bending test device was used to perform single-bending,bending-unloading,and cyclic bending tests,obtaining the bending moment-curvature curves and achieving the design goals.In addition,tensile tests were conducted,and the tensile test data and bending test data were applied to finite element simulation of the roll bending forming process,and compared with the springback results of the roll bending forming test.The results showed that in the roll bending simulation and test of V-shaped parts with a single pass forming of 20 ° and 30 °,the springback prediction accuracy of bending test data increased by 32.9% and 31.9% respectively compared with the tensile test data.