Simulation Study On Hydraulic System Of Flexible Pressure Straightener With Wide And Thick Plates

With the development of national industrialization,the market demand for wide and thick plates is increasing.Due to the uneven rolling and cooling process caused by the plate thickness,the wide and thick plates are often bent in one direction,which is not in line with the industrial demand.Wide and thick plates are difficult to be processed by roller straightening machine.And the domestic pressure straightening machine is generally a large hydropress with a movable cylinder,which straightening by workers' experience.It's not fully automated.In this regard,some scholars put forward a multi-head straightening method of staggered arrangement of cylinders that can be used to straighten the wide and thick plate of arbitrary bending.A high degree of automation can be achieved by measuring the shape of plates to be straightened by laser detector and calculating the distribution pressure down strategy and pressure down amount.Starting from the straightening scheme,the hydraulic system of multi-point flexible pressure straightening equipment was designed,and the possible problems in the straightening process were theoretically analyzed and optimized.With MATLAB/Simulink as the tool,the simulation verification was carried out.In this paper,based on the theory of multi-point flexible pressure straightening,the load characteristics of the straightening under typical working conditions are obtained by ABAQUS simulation,and the hydraulic system of the multi-point flexible pressure straightening equipment is designed on this basis.The hydraulic system is multi-cylinder parallel system and its hydraulic cylinder can be controlled separately.Its hydraulic energy is constant pressure variable pump,control elements is servo valves.The hydraulic system uses the displacement of the cylinder as feedback for servo control.In the process of analyzing the performance of hydraulic system,the mathematical model of valve-controlled asymmetrical cylinder unit was firstly established.And then the response process of the system under different working conditions was simulated by MATLAB/Simulink to ensure that the system met the requirements of straightening process.The influence of the undetermined variables is simulated and analyzed,among which the large influence is the stiffness of the wide and thick plate.In order to explore its influence principle,the system is analyzed in frequency domain.Based on the sensitivity theory,the influence of each system parameter is quantitatively analyzed and used it as the basis for optimizing the system.In this paper,the interference of multi-cylinder working at the same time is analyzed from multiple angles,and the compensation strategy of frame deformation is put forward.The fuzzy theory is used to modify the PI controller parameters to improve the dynamic response performance and robustness of the system.At the same time,the composite control system is composed of load feedforward and displacement feedback.Finally,the anti-interference ability of the system has been improved obviously.