基于快速开关阀的压力机快速液压系统的研究

【作者】 丁小艺；

【导师】 孙友松；

【作者基本信息】 广东工业大学 ， 材料加工， 2003， 硕士

【摘要】 数控回转头压力机是由计算机控制的柔性板材冲压加工设备，液压传动式数控压力机除了具备传统数控压力机的特点外，还具有步冲频率高、结构简单、维护简单、安全可靠等特点，在国内外得到了越来越广泛的应用。我国目前生产的数控压力机大部分都为机械传动式，液压传动的数控压力机在国内市场上还比较少，而且所用的液压系统都是从国外进口。 电液伺服阀由于控制精度高，动态响应好等优点，在液压控制中已得到了广泛的应用和发展。但同时它也存在着抗污染能力差、能耗大、控制电路复杂、价格较高等缺点。同时由于滑阀流动阻力大，通流能力小，不能满足高速或大型液压设备对流量的要求。 为了克服伺服阀和滑阀的不足，本文所研究的基于快速开关阀的快速液压系统采用快速开关阀作先导阀，控制逻辑阀的开启和关闭，从而控制液流的通断和压力的高低、流量的大小，以实现对活塞运动方向、速度的控制。本文所研究的快速液压系统，应用于数控回转头压力机在国内尚属首次。 本文在初步确定了系统的两种方案的基础上，比较分析了各方案的优缺点，并对两种方案运用MATLAB WITH SIMULINK软件包进行动态仿真，分别得出了系统的位移曲线、速度曲线和油缸上、下腔的压力曲线。在仿真的基础上，再对这两种方案进行实验研究，并将实验曲线与仿真曲线进行比较，提出了系统的改进意见。 从仿真和实验研究可得出如下结论和建议： (1) 本课题所研究的采用快速开关阀作先导阀控制逻辑阀的快速液压系统，是比较可行的方案。该系统的结构简单。在空载的情况下，已基本能达到所要求的性能，其工作行程可达6mm，步冲频率可达300次／分。 (2) 原设计中，由于活塞和活塞杆的面积差很小，回程上行时，系统压力会迅速升高造成溢流阀的溢流而使回程速度降低，从而降低了系统的工作效率。 (3) 从逻辑阀的结构来看，由于逻辑阀芯是靠线接触来实现密封的，长期在快速冲压的条件下，其使用寿命尚待考验。 广东工业人学工学顾十学位论义 （4）为进一步改进设计方案，提高其工作性能，在主油路中加一液动 换向阀，控制活塞的差动，从而将减小油缸和活塞的尺寸，提高 工作性能。 （5）限制逻辑阀的开口量，可提高逻辑阀的快速换向性能，从而可缩 短活塞的回程时间，提高系统的工作效率。 从对改进后的方案进行仿真的结果可知，改进后的方案在性能上都有一定程度的改善。更多还原

【Abstract】 The CNC turret press is a kind of computer controlled flexible sheet punch processing equipments. In addition to the characters of traditional CNC turret press, the hydraulic CNC turret press has the characters of high stepping frequency, simple structure, easy maintenance, safety and reliability, It has been applied more and more extensively at home and abroad. Most of the CNC presses produced in our country are mechanical. There are few hydraulic CNC presses in our country. All the hydraulic systems were imported from foreign countries.Because of the high controlling precision and the fast dynamic response of the electrical-hydraulic servo valves, they are widely used in hydraulic control systems. But they have the disadvantages of the poor ability for anti-pollution, the huge waste of energy, the complexation of the controlling electric circuit and the high price. Because of the high flow resistance and the poor flowing ability, the spool valves can’t meet the requirements for high velocity or huge hydraulic equipment.In order to overcome the disadvantages of servo valves and the spool valves, the fast hydraulic system controlled by the fast on-off valve is researched which uses the on-off valves as the pilot valves. They are used to control the opening and closing of the logic valves, thus they can control the pressure and the flow. So they can control the movement direction and the velocity of the piston. The fast hydraulic system studied in the paper is applied in the CNC turret press in our country for the first time.On the basis of the initial experiment systems in this paper, the advantages and the disadvantages between the two experiment systems have been compared and analyzed, and MATLAB WITH SIMULINK software has been used for the numerical simulation. On the basis of the artificial, the displacement curve, the velocity curve and the pressure curve of the oil crock are obtained. On the basis of simulation, the two experimental systems are studied. The results of the experiment and the simulation are compared. The suggestions to improve the system have been gotten.From the research of the experiment and the simulation, conclusions and suggestions are gotten:(1) The fast hydraulic system which uses fast on-off valve as the pilot valves to control the logic valve is an available system. The system is simple. It can meet the requirements under the condition without loads. The working stroke is 6mm. And the stepping frequency is 300times/minute.(2) In the original system because of the area between the piston and the piston pole is too small, the system pressure will rise when in the return stroke. And the reliever valve will open. The return velocity will reduce. So the working efficiency is low.(3) From the structure of the logic valve, as the poppet valve is sealed by a line touching, the service life should be tested.(4) In order to improve the system and its working function, a hydraulic controlled direction valve is connected in the main oil circuit to control the differential of the piston. Then the dimentions of the cylinder and the piston are reduced, improving the working properties.(5) If the opening of the logic valve is limited, the fast transformation function of the logic valve will be improved, and the returning time of the piston will be reduced. Then the working efficiency is improved too.The improved project is simulated. From the simulation results, the better characters have been gotten.更多还原