A passive dynamic leveling control system of hydraulic press and its control method

Abstract

The invention relates to a passive type dynamic levelling control system of a hydraulic machine. The system comprises a controller, a constant-pressure oil source P1, a high-pressure oil source P2, an oil tank, a first displacement sensor, a second displacement sensor, a third displacement sensor, a fourth displacement sensor, a first dynamic levelling hydraulic sub-system S1, a second dynamic levelling hydraulic sub-system S2, a third dynamic levelling hydraulic sub-system S3, and a fourth dynamic levelling hydraulic sub-system S4, wherein each of the first, the second, the third and the fourth dynamic levelling hydraulic sub-systems is composed of a first check valve, a first, a second and a third electromagnetic ball valves, and a first, a second and a third levelling overflow valves; the oil inlets of the first, the second and the third electromagnetic ball valves are communicated with each other and connected with a rodless cavity of a first levelling hydraulic cylinder; the oil outlets of the first, the second and the third electromagnetic ball valves are respectively connected with the oil inlets of the first, the second and the third levelling overflow valves; and the oil outlets of the first, the second and the third leveling overflow valves are communicated with each other and connected back to the oil tank. The passive type dynamic levelling control system provided by the invention has the advantages that the antijamming capability is high and the stability is high.

Description

technical field [0001] The invention relates to a hydraulic control system, in particular to a passive dynamic leveling control system of a hydraulic machine and a control method thereof. Background technique [0002] The dynamic leveling control system of the movable beam of the hydraulic press is widely used in metal die forging forming equipment, metal stretch forming equipment and composite material compression forming equipment. The application of the dynamic leveling control system of the movable beam of the hydraulic press can significantly improve the precision of the workpiece, reduce the wear of the mold, and prolong the life of the press. It has become one of the key technologies to measure the manufacturing level of the hydraulic press. The breakthrough and improvement of related technologies have important significance. [0003] At present, the design of the dynamic leveling control system of the hydraulic press mainly revolves around the following two aspects:...

AI Technical Summary

Problems solved by technology

[0006] (1) The manufacturing and maintenance costs of the electro-hydraulic proportional dynamic leveling control system are high

In the prior art, the electro-hydraulic proportional control system is mostly used for dynamic leveling of the movable beam of the press. Although it has high control accuracy, multi-axis controllers are often used in combination with proportional valves and proportional servo valves or multiple proportional valves are used. The structure of the leveling control system constitutes a leveling control system, which greatly increases the manufacturing cost of the hydraulic machine; or the proportional valve is used to directly control the return cylinder. Although the structure is simplified, the disadvantage of high manufacturing cost of the leveling control system cannot be avoided.

[0007] (2) The algorithm of the electro-hydraulic proportional dynamic leveling control system is complex and difficult to control

Most of the existing technologies use PID controllers and set virtual axis models to perform closed-loop control on four high-response proportional servo valves or proportional directional valves, and then perform closed-loop control on four leveling hydraulic cylinders or return cylinders to achieve passive adjustment. However, in the process of actual press commissioning and maintenance, it is necessary to select the key setting parameter proportional gain K of the PID controller according to the experience of the engineer. P , integral gain K I , differential gain K D , and further carry out more complicated debugging, so as to obtain the key setting parameters of the PID controller suitable for the press under actual working conditions, which greatly increases the time and difficulty of debugging and maintenance, and increases the cost of production and maintenance

[0008] (3) The anti-interference ability of the electro-hydraulic proportional dynamic leveling control system is poor, and the design of the electrical system is difficult

In the prior art, the form of analog signal output is mostly used to control the displacement of the proportional valve or servo valve spool, and then realize the dynamic leveling control of the four leveling hydraulic cylinders or return cylinders. However, due to the analog output form Its own characteristics make its required hardware requirements and environmental requirements higher, making the design of the electrical system more difficult, and its anti-interference ability is poor, and the probability of being affected by complex environments in actual working conditions is greatly increased, thereby reducing the entire electrical system. Stability and applicability of liquid control system

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