基于高速开关阀的液压缸速度控制系统仿真研究

发布时间：2018-11-08 06:51

【摘要】：如今,随着计算机的迅速发展和广泛应用,液压工业作为全球性的工业,也在不断与计算机结合走向数字化。所以在液压系统中的阀也多用比例阀、数字阀、伺服阀作为放大元件。阀作为液压系统的重要元件,影响着整个系统的性能,甚至影响着整个机械设备的优越性、可靠性、效率以及寿命,所以阀的选取显得尤为重要。高速开关阀由脉冲信号对电磁铁的控制来实现对阀芯的推动作用。高速开关阀只有“开”和“关”两种形式,只要控制脉冲频率或脉冲宽度,就可以控制“开”和“关”的时间。高速开关阀以其结构简单,抗污染能力强等优点被广泛应用。本文对将高速开关阀应用于高速滚珠旋压系统的压下平台的速度控制系统进行了可行性分析与性能研究,以高效、经济、结构简单、容易操作为出发点设计出用高速开关阀代替其他伺服换向阀的液压系统,由高速开关阀独立控制流量,同时也为滚珠旋压机的更新优化提供参考。根据高速滚珠旋压机的原理与工况要求,确定液压系统执行元件及液压缸所承受负载力,液压缸所要达到的最大工作速度等,从而设计计算出液压缸尺寸,确定液压系统工作压力以及所需流量。为了验证基于高速开关阀的液压系统对液压缸控制的可行性与稳定性,本文根据所建立的系统基本方程,搭建开环系统的Simulink仿真模型,得到变占空比定负载下的液压缸速度曲线等,定占空比变负载下的液压缸速度曲线等,对占空比与负载对系统的影响进行分析与总结。建立系统传递函数,在Simulink中搭建传递函数模型,绘制Bode图,判定系统稳定性。仿真结果表明:此液压系统对液压缸速度控制是可行的,且系统稳定。但负载按照不同线性变化规律变化时,对液压缸速度影响较大。在滚珠旋压过程中,滚珠旋压机轴向力不断变化会使进给速度发生变化,而进给速度稳定与否直接影响着旋压精度,为消除负载变化对液压缸速度的影响,本文在系统中引入PID控制器,组成速度控制闭环,利用AMESim模型仿真出液压缸受到不同变化规律的负载作用下、通过对PID参数整定后的液压缸速度仿真曲线。仿真结果表明:此方法可使液压缸速度基本不受负载的影响,可进一步提高系统抵抗负载变化的能力,保证旋压进给速度不变,从而进一步提高旋压精度。最后实验得到有电磁换向阀的液压缸位移历史趋势,与无电磁换向阀的仿真结果进行对比,并分析前者波动原因与劣势。
[Abstract]:Nowadays, with the rapid development and wide application of computer, hydraulic industry, as a global industry, is constantly combined with computer to digitize. So the valves in hydraulic system also use proportional valves, digital valves, servo valves as amplifiers. As an important component of hydraulic system, valve affects the performance of the whole system, and even affects the superiority, reliability, efficiency and life of the whole mechanical equipment, so the selection of valve is particularly important. High-speed on-off valve is controlled by pulse signal to drive the valve core. There are only two types of "open" and "close" of high speed valve. As long as the pulse frequency or pulse width is controlled, the time of "on" and "off" can be controlled. High-speed on-off valve is widely used because of its simple structure and strong anti-pollution ability. In this paper, the feasibility analysis and performance study of the speed control system of the high speed switch valve applied to the high speed ball spinning system are carried out in order to be efficient, economical and simple in structure. The hydraulic system with high speed switch valve instead of other servo directional valve is designed for easy operation. The flow rate is independently controlled by high speed switch valve, and it also provides a reference for the renewal and optimization of ball spinning machine. According to the principle and working condition requirement of high-speed ball spinning machine, the load force and maximum working speed of hydraulic system actuator and hydraulic cylinder are determined, and the size of hydraulic cylinder is designed and calculated. Determine the working pressure and required flow rate of hydraulic system. In order to verify the feasibility and stability of the hydraulic system based on high speed switch valve to control the hydraulic cylinder, the Simulink simulation model of the open loop system is built according to the basic equations of the system. The hydraulic cylinder velocity curves under the variable duty cycle and the constant duty cycle load are obtained. The effects of duty cycle and load on the system are analyzed and summarized. The system transfer function is established, the transfer function model is built in Simulink, the Bode diagram is drawn, and the stability of the system is judged. The simulation results show that the hydraulic system is feasible to control the speed of the hydraulic cylinder and the system is stable. But when the load changes according to the different linear variation law, it has a great influence on the hydraulic cylinder speed. In the process of ball spinning, the constant change of axial force of the ball spinning press will change the feed speed, and whether the feed speed is stable or not will directly affect the spinning precision, in order to eliminate the influence of the load change on the hydraulic cylinder speed, In this paper, a PID controller is introduced into the system to form a speed control closed-loop. The hydraulic cylinder is simulated by using AMESim model under the load of different changing laws, and the simulation curve of the cylinder speed is obtained by setting the PID parameters. The simulation results show that this method can make the speed of the hydraulic cylinder almost independent of the load, and further improve the system's ability to resist the change of the load, ensure the constant speed of spinning feed, and further improve the spinning accuracy. Finally, the historical trend of displacement of hydraulic cylinder with electromagnetic directional valve is obtained, and the simulation results of non-electromagnetic directional valve are compared, and the reason of fluctuation and disadvantage of the former are analyzed.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH137.51;TG305

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