| Since the21st century, with the diverse needs of people and the improvingdemands for Product accuracy, Enterprise production also goes towards the directionsof Flexible machining and precision, thus various kinds of precision forging equipmentemerged. Hydraulic press is a kind of forging machinery which is widely used in metalforming and processing zones, traditional precision hydraulic press is based on valve-controlled electro-hydraulic servo system, which is energy wasting, noisy, andsimultaneously, the servo valve is easily to be polluted which will lead to a damage.Therefore, developing an energy-saving, environmentally friendly and high accuracyhydraulic press is trends for the future.Under the premise of extensively reviewing the related product information andthe academic literature, current research situation and development trends of forgingmachinery is overview in this article, meanwhile, a new kind of hydraulic system, i.e.direct-drive volume control hydraulic system (DDVC) is introduced, then theadvantage and practicability of applying the DDVC to the precision hydraulic press isexpounded. Based on a deeply analysis on the characteristics of the different forms ofthe DDVC, a fire new variable displacement DDVC is designed. The system consist ofAC servo motor, variable pump, powered oil make-up equipment and other auxiliarycontrols. Referring to the technical criteria of related books on hydraulic press, thestructural parameter of the hydraulic system is computed and optimized. According tothe given parameter, the system stability and restricted factors is analyzed. In theAMESim simulation platform, the nonlinear PID controller is designed, at the sametime, the displacement adjusting strategy in the process of changing the velocity isdeeply analyzed. After all these having been done, a series of simulation is executed inthe AMESim platform about the kinetic characteristics of the system. Owning to the order cycle of the variable pump is too long, it is incapable ofdemonstrating the practical running behavior of the variable displacement DDVC forthe moment. Simply, a demonstration experiment is carried out using the traditionalDDVC in the Lab. During the experiment, a PC control procedure is written by VisualC++programming tools, then the system is set up. Aim on the step input, slope inputand the sine input signals, the experimental investigation is done and the experimentdata is analyzed, analytical result is helpful in improving the performance of theDDVC. |
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