Research On Leakage Compensation Control For The Heavy Forging Press Under Low Velocity

Due to the narrow range of forging temperature, the large resistance to deformation and the strict deformation rate of the large precision die forgings, conventional forging methods are unable to meet the requirements of forging capacity. Isothermal forging processing technology is an important way to solve this problem, but the isothermal forging processing technology requires the heavy forging press has the ability to steady movement(speed fluctuation<10%) under low speed(0.2mm/s) process. However, the heavy forging press under low velocity stage is extremely easy to engender the instability phenomenon of the velocity jittering and low-speed stick-slip which due to the leakage of the system, the nonlinear friction and the oil source pulse, thus greatly degrade the quality of the products. In order to improve the stability of the system that is running in low speed status, corresponding compensation control strategies must be established based on the research on the mechanism and effects of various factors on the stability of the system. Therefore, this paper takes the low-velocity driving system of the heavy forging press as the object, and the influence mechanism and compensation control of the leakage impact on the stability of the system were studied. The main contents of this thesis are as follows:(l)The low-speed driving system including leakage model of the heavy forging press was established. Based on the analysis of leakage mechanism and detection theory, considering the impacts of leakage, the mathematical model of the low-velocity driving system was built up. And the influences of leakage on the low-speed stability of the system were analyzed based on linear system theory. For many parameters of the mathematical model are unknown, the physical model which contains the leakage model was established based on the AMESim software. The parameters of simulation were determined upon the actual system and the availability and accuracy of the simulation model was verified reference to samples of the components. Finally, the simulation model which can reflects the true low-velocity system of the heavy die-forging press was acquired.(2) The stability of the low-speed for the heavy forging press was analyzed. According to the mathematical model and physical model, by using the method of theoretical analysis and simulation analysis, the influence laws of the key parameters to the low-speed stability were revealed such as system leakage, oil bulk modulus, viscous friction coefficient, the initial length of piston cylinder and so on. And then the corresponding measures were put forward to improve the quality of response of the system.(3) Research on the leakage compensation control for the low-speed driving system of the heavy forging press. Aiming at the influences of leakage on the stability of low speed system for the heavy forging press, by using the methods of co-simulation of AMESim software and MATLAB/Simulink software, the leakage feed-forward compensation of the system and compound controller based on the conventional PID feedback was designed, and it was applied to low-speed driving system motion control for the heavy forging press. The effects of the compound compensation control strategy that based on PID are compared with the effect of the conventional PID leakage compensation control method, and the simulation results show that the compound compensation control method based on PID is better than the conventional PID leakage compensation control scheme. Finally, the validity of the conclusions was verified through the315T experiment platform. Full total figures48,...