Abstract
The characteristics of electro-hydraulic servo system of full-hydraulic leveler are high speed, large inertia, high frequency response, and multi-degree of freedom. In order to improve the degree of automation of full-hydraulic leveler and achieve the simultaneous control between position and pressure, the position–pressure cooperative control strategy is presented in the article. In the working process, the dynamic working pressure signal of the hydraulic cylinder is turned into a real-time position signal by the pressure–position conversion gain and then compensates the converted signal into the position closed loop. Meanwhile, the pressure signal of the rear cavity of the hydraulic cylinder is fed back to the input of the proportional relief valve at the pump source, and then the system work pressure changes quickly according to the different thickness. In this article, the mathematical model of position–pressure cooperative control of hydraulic straightening machine is established. The simulation results in AMESim software verify the correctness of the control strategy. Finally, the feasibility and practicability of the control strategy are verified by the field prototype of 11-roller full-hydraulic leveler. The control strategy provides the theoretical basis for designing the electro-hydraulic servo system.
Highlights
The production level and quality of heavy and medium plate represent the developmental level of a national steel industry
In the process of straightening heavy and medium plate, the traditional control method mainly focuses on position closed loop which can guarantee the control and track of hydraulic cylinder displacement,[4,5] but unable to achieve online real-time control of pressure
Pressure rapid response curve of four-cylinder synchronization presents that the pressure curve can quickly respond to reach the target pressure values (17 and 22 MPa) through the position–pressure cooperative control strategy
Summary
The production level and quality of heavy and medium plate represent the developmental level of a national steel industry. The position–pressure cooperative control fourcylinder synchronous motion experiments of fullhydraulic leveler are as follows: (1) verify the pressure quick response and four-cylinder synchronization at the condition of no-load; (2) verify the stability of the four-cylinder synchronization by straightening 18-mmthick Q235B and 24-mm-thick Q235B. Pressure rapid response curve of four-cylinder synchronization presents that the pressure curve can quickly respond to reach the target pressure values (17 and 22 MPa) through the position–pressure cooperative control strategy. The maximum deviation between the actual roll gap and the target roll gap is within 0.15 mm, while the average deviation is controlled within 0.078 mm, which can meet the actual production needs
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