| Large bridge gantry machining center has been widely used in today’s aerospace industry defense industry, and large-scale mold processing industry and other manufacturing and processing on the key products of the heavy machinery, it can achieve high-speed, high efficiency, high-precision cutting, especially high-speed machining for some pieces of the overall structure of large and complex.This thesis is based on a plant of the bridge gantry machining center hydraulic system project, it discusses the whole process of designing and researching the the hydraulic system of this kind of gantry machining center, and focuses on spindle ram balance part of the hydraulic system.In the Z-axis for the bridge gantry machining center, the ram load is very heavy.When the ram works, it has a big impact on the Z-axis motor and ball screw, it is easy to work long hours burning motor, causing the ball screw wear, reduction of working life. To solve these problems, increasing the balance tank on the ram to balance the most of the gravity in it. This approach will greatly reduce the Z-axis motor and ball screw’s force and torque, which is conducive to a smooth motion of Z-axis, and can play a security role when a sudden loss of power in the machine tool or an accident occursThis paper useing the three-way proportional pressure-reducing valve, which has the characteristics of high pressure control accuracy and good dynamic, designs a cylinder valve hydraulic system. This system can make the oil pressure in the balance oil tanks move effectively ang quickly following the ram and achieve stability gradully,so that play a role of balbacing the force in the vertical direction of ram. And at the same time, this paper makes research on this hydraulic system through the MATLAB/Simulink software and DSHplus an-alyzed the hydraulic system, controls by the addition of fuzzy PID algorithm to shorten the response time,and further enhances the system’s dynamic response. |
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