Design And Research Of Proportional Servo Control System For CNC Bending Machine

CNC bending machine is a kind of precision forming machine tools used to bend the workpieces for the required sections, which is based on the CNC system function of pinpoint, test and control. The development of proportional servo control technology and production process have increased the requirements of control performance and synchronization accuracy of the bending machine. In this dissertation, a proportional servo control system is designed in order to meet the development needs of CNC bending machine, and the system is both analyzed and studied. Job that this dissertation accomplished is mainly as follows:Based on the requirements of the control performance and bending precision of the bending machine, the structure model of the bending machine is established. The design of CNC bending machine servo control system is completed, including the design and parameter selection of electrical system and hydraulic system. The main hardware components of the servo system of the bending machine are selected.The bending machine's load system must have quicker response and high precision for improving the quality of products. By using of the nyquist criterion and the minimum phase method, the stability and stability margin of nonlinear mathematical model established from the electro-hydraulic proportional servo control system are verified. Aimed at nonlinearity and time variation, two control strategies which include PID and Fuzzy-PID control are represented and simulated for the elimination of the steady state error and improvement of the control precision. The result shows that the Fuzzy-PID overcomes the shortcomings effectively, which the control parameters are difficult to be adjusted. The whole performance of the system has been improved obviously.Finally, according to the requirements of double cylinder synchronization accuracy, the simulation model of hydraulic synchronization system is established and simulated in AMESim. The simulation result shows that the bending machine has good double cylinder synchronization performance, and it can meet the requirement of the application. In view of the synchronous deficiency, the factors which affect the synchronization performance are studied, and the measures are put forward to improve the precision of synchronization control.