基于PLC和触摸屏的气辅挤出气体控制系统的设计*

Design of Gas Control System for Air-Assisted Extrusion Based on PLC and Touch Screen

基于PLC和触摸屏设计了一套气体控制系统。其包含的气体加热装置为内含加热棒的容器。该容器上安装有压力与温度传感器。当触摸屏设置的目标控制参数与检测到的值存在偏差,可编程逻辑控制器(PLC)将进行比例积分微分(PID)运算与脉宽调制(PWM),并将转换后的控制信号分别输出到气压电磁阀与固态继电器(控制加热棒),最终实现气体压力与温度的调节。经试验证明,该系统控制精度高,人机界面简洁美观,具有良好的可扩展性,在聚合物气辅挤出实验中运行稳定。

A gas control system was designed based on programmable logic controller (PLC) and touch screen. Gas heating device within the system was a container with a heating rod. A pressure sensor and a temperature sensor were fixed in the container.When the values detected by the sensors deviate from the values set in touch screen,instructions such as proportion integral derivative (PID) and pulse width modulation (PWM) would be executed by PLC. Thus,it send control signals to a electro-pneumatic valve or a solid state relay that was used to control the heating rod. As a result,the gas pressure and temperature would be adjusted.The test result show that the system has high control precision,simple and beautiful man-machine interface and good expansibility. It runs stably in the experiment of polymer gas -assisted extrusion.