| Heavy forgings quality and production capacity is one of important symbols, which can measure a country ’s industrial development level. Large hydraulic press is an equipment for heavy forgings forming, and it’s essential to improve the control performance of power transmission system. Component and system researched for large water press power transmission system to improve its performance have great theoretical and practical significance.At present, large hydraulic machine generally adopts the control mode of oil water control, and the traditional form of eight valve of distributor was used in water system, there are two major problems in power transmission system : the first is the main control valve in water system of eight years without valve distributor application improved flow linearity control exists the problem of bad effect, the overall control performance; the second is oil servo system and water system did not do in-depth integration of the overall control, control the overall performance improvement. Aiming at the above problems,this paper focuses on the following research work:(1) The orifice arrangement form of the inlet valve cup is the research object. The flow area of inlet valve port is calculated and optimized, and the best coincidence degree value is calculated. The finite element model of the inlet valve and outlet valve is established. And then the flow- displacement curve and pressure-displacement curve have been gotten, so has the flow filed distribution. The flow- displacement curve of the optimized inlet valve is verified by using the test platform of 60 MN free forge hydraulic press.(2) The mathematical model of fluid power transmission system, including water pump, inlet valve, outlet valve, main distributor, prefill valve, pipeline, actuator, load, working medium, electro-hydraulic servo system, is established. The complete mathematical model of fluid power transmission system is derived, which lays a theoretical foundation for the follow-up study.(3) based on electro-hydraulic position servo control system mathematical model of hydraulic press, in order to improve the static and dynamic characteristics of hydraulic press servo system, the load characteristics of the electro-hydraulic position servo control system are analyzed. In order to improve the quality of forgings, ensure the controllability of the control system under the external disturbance, improve the robustness of the electro-hydraulic position servo control system, the strategy of active disturbance rejection control is presented. With the help of MATLAB/Simulink software, build the simulation model of active disturbance rejection control, analyse simulation results, and lay the foundation for the experimental research.(4) Simulated and experimental research have been carried on for the control characteristics of the 60 MN free forging hydraulic press. This paper introduces the experiment to test the 60 MNfree forging hydraulic press system, method of data collection and data analysis tools. Established the joint simulation model of fluid power transmission system and hydraulic transmission system, respectively, carried on the simulation analysis of the system for control characteristics of the system in conventional forging and fast forging two conditions, the accuracy of the simulation model is verified by experiment. For poor robustness of servo system, weak ability of anti interference problem, adopted the active disturbance rejection control method to analyse the control performance of hydraulic press under the load and different loading force. |
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