| Forging equipment plays an important role in the development of national economy.Forging production covers many field including national defense industry,machine-tool industry,power generation industry,transportation industry and civil industry,and so on.The history of the forging equipment is more than 200 years in the international community,while it only developed for decades in china.After many years of introduction,digestion and absorption,domestic forging equipment has the ability of independent research and development,and has achieved considerable results.However there is still a certain gap between the domestic and international levels of the forging hydraulic technology.For the forging hydraulic press the control performance of the hydraulic system directly affect the rapidity,accuracy and stability of the whole equipment.Therefore,studying on the control system of the forging hydraulic press has significance both in theory and practiceIn this paper,a 65MN forging hydraulic press is taken as the research object.Its working characteristics are studied to improve the quality and operation stability of forgings.The main research contents are focused on improving the control accuracy and operation stability of forging hydraulic press during operation,they are shown as following.Firstly,to clarified working principle and the working cycle of the foring process,the structure of forging hydraulic press and the composition of hydraulic control system are analyzed.Secondly,the working principle of the main control valve is analyzed in the hydraulic system of forging hydraulic press.Then,the mathematical model of the valve-controlled asymmetric cylinder system with independent metering control of forging hydraulic press is established.The model could provide theoretical support for simulation analysis in the next.Thirdly,a compound control strategy of velocity position is proposed.The problem of poor control accuracy and low forging efficiency of the existing large forging hydraulic press can be solved.At the same time,a multi-disciplinary simulation model of the forging hydraulic press control system is built by the software of SimulationX.Then the operation characteristics of the forging hydraulic press under the classical PID feedback regulation and velocity-position compound control feedback regulation are compared and analyzed.Fourthly,the forging frequency and engineering parameters,which affect the forging efficiency and quality,are simulated and analyzed in the compound control strategy of velocity position.Finally,thestability of pressure control during pressure relief of forging hydraulic press is lucubrated.The pressure relief curve based on the principle of energy uniform release is designed by analyzing the mechanism of pressure relief,and the noise intensity is used as the quantitative index of pressure impact.The pressure relief curves of uniform energy release are simulated and analyzed,and it is also compared with the simulation curves of pressure relief effect in different pressure relief processes.Based on this study,the simulation analysis of the working characteristics of the forging press hydraulic system under different piping and system parameters is performed.The results are shown as followingsIn this paper,the compound control strategy of velocity position can significantly improve the forging performance and precision of the 65MN forging hydraulic press.Compared with the traditional PID position closed-loop control system,the compound control strategy of velocity position allows the moving beam of forging hydraulic press to run in accordance with the set displacement curve and velocity curve without delay,and can realize high precision positioning.The positioning accuracy can reach within 0.3mm.In the aspect of pressure control stability,the proposed pressure relief curve based on the principle of energy uniform release can make the pressure relief of working hydraulic cylinder smooth and fast.The proposed research method improves the control stability and fast operation characteristics of forging hydraulic press,and has important practical significance and application value in improving forging quality and achieveing safety forging. |
PDF Full Text Request