Study Of The Structure And Performance On The Hydraulic Servo System Of Multilayer Press Based On Displacement Control

The hot press is the executing mechanism of the hot-pressing process in the production process of wood-based panels,and plays a decisive role in the quality of the wood-based panel products.Multilayer press has affected the mechanical properties of the slabs such as the consistency and the uniformity of slabs' thickness,due to there are disadvantages in the press such as low closing precision of hot press plates,poor synchronization performance of multi-cylinder,uneven pressure distribution between plates,etc.All these questions lead to the poor quality of the man-made board produce with multilayer press.In order to improve the quality of the plate,this paper research the structure and performance on the hydraulic servo system of multilayer press,regard the position of the press' main cylinder(hot platen position)as the object of the displacement control during the hold press and repressurization section.Used the technology of hydraulic servo control system to achieve the purpose of improving the closing precision of hot press plates on multi-layer press,thereby improving the quality of the man-made board product which be made with the multi-layer press.In this paper,a domestic multi-layer press is taken as a reference.Combined with the working characteristics of the multi-layer press,the craft and load of the multi-layer press hot-pressing process are analyzed.According to the problems existed in the multi-layer press,improved its hydraulic system with servo control technology,finished the design of the multi-press hydraulic servo system,which including the hot platen quick closing hydraulic circuit and the multi-cylinder synchronous motion hydraulic servo circuit.A multi-press main cylinder with double functions,single-acting piston cylinder and double-acting piston cylinder,was designed to meet the requirements of working environment and servo control.Established the mathematical model of each part of the multi-press hydraulic servo system composition unit,and then the open-loop transfer function of the system was obtained.Used the MATLAB software to analyze the stability,rapidity and accuracy of the system,determining whether the system can meets the design parameters and functional requirements in steady-state error,time-domain response and dynamic error.AMESim was used to model the components of the multi-press hydraulic servo system,and combined them into the composition unit model of this system.Used the "Batch" function to regulate the system forward control process,get the appropriate forward gain to improve the system control accuracy.Run the composition unit model and analyzed whether the piston's output displacement trajectory meets the requirements under the general loading status and the status existed error at initial position.Next,built the model of the multi-cylinder synchronous motion hydraulic servo circuit,simulated and analyzed the accuracy of synchronization between individual cylinders,then verified the closing accuracy and closing synchronism of the hot plate.The results show that the multi-press hydraulic servo system has the characteristics of good stability,high response speed and high synchronization accuracy,and meets the requirements of the multi-layer press for its hydraulic system.Therefore,the purpose of improving the degree of automation control and the quality of the man-made board produce with multilayer press has been realized.