Simulation And Analysis On Hydraulic Control System Of CNC PM Press

The study object of this dissertation is hydraulic control system of CNC PM press. The main study method is system modeling and computer simulation. Firstly, the closed-loop control system of hydraulic press was proposed in the thesis, and the type of the components was selected. In our simulation, two kinds of simulation softwares were used. On one hand, the system transfer function models were established, and to the close-loop control system of displacement, velocity and pressure was simulated by using MATLAB/SIMULINK. The fundamental performance of the three parameters was, analyzed, which proved that the selection was feasible. On the other hand, some more complex working conditions during press were simulated by using AMESim. The main content of this dissertation includes: the simulation of multiple punches two-direction pressing, the results showed that the position of punches can be controlled exactly; the simulation of the press of multi-steps-profile parts, the velocity of punches was set in proportion to steps, the results proved that the press can coordinate for each punch. The cause of powder transverse shift is considered because of the unequal of pressure, and proposed the solving method - the volume ratio of pressed powders to punched powders of each punch must keep equal in order to obtain the the equal pressure at each step based on the relationship of density and pressure. Finally, an example of pressing was given, the workflow for press was designed. The speed control curve for each hydrocylinder was obtained according to the punch movement and part size. The performance of control system was analyzed comprehensively based on the simulation results. It can be concluded that the precise control of displacement and velocity of each punch can insure the proportion of punched powder shape to compaction shape to prevent from powder transverse shift. The produced part is size exactly and density uniform, and can meet the requirements.This research can provide us not only a good reference for the component selection by the fundamental performance parameters of system, but also a theoretical basis for design and experiment of the press.