Research And Development Of Twin-screw Extruder Control System

The feed industry has developed rapidly since the 21 st century.With the introduction of the German Industry 4.0 and China Manufacturing 2025 strategy,smart manufacturing has become the mainstream of the times at the same time.China is inspiring to transform from a manufacturing power to a manufacturing power.It encourages companies to build smart factories,and promotes corporate upgrading and transformation.The feed industry which is a key target of the national manufacturing industry requires feed factories and mechanical equipment to develop in the direction of automation and intelligence.This article relies on the basic research plan of Jiangsu Province to research and design the control system of the feed extrusion equipment-twin screw extruder based on the above background.The control system can monitor the process parameters of the extruder in real time and control the automatic operation of the whole machine.An alarm can be issued for faults in the work process.The specific work content of this article is as follows:(1)First,I determine the control requirements of the system according to the working process of the twin-screw extruder,analyze and design the data acquisition subsystem,give a data acquisition plan and select the sensor.Then the overall plan of the extruder control system is given according to the control requirements.The hardware selection and IO address allocation of the control system are completed according to the control input and output.Finally,the main circuit of the control system is designed.(2)I use CFX to establish the entity model and flow field finite element model of the extrusion flow channel of the twin-screw extruder.Then I analyze the flow field and study how three important factors which are screw speed,material moisture content and temperature influent extrusion process.Finally,I determine the influencing factors of the extrusion temperature value,which provides a basis for subsequent temperature control.(3)The traditional extruder does not fully consider the temperature control.In actual production,the size of the feed and the temperature of the feed will affect the extruded temperature.Aiming at the actual production characteristics of the extruder,this paper introduces feedforward compensation and dynamic matrix algorithms into the traditional temperature control System and put forward a dual-loop control method based on feedforward and DMC-PID.This method can consider the influence of multiple factors on the temperature and perform predictive control.Compared with the traditional cascade PID control,this control effect is better.(4)I use TIA V15.1 to design the PLC control program in detail,including the main program and four subroutines(weighing,current,temperature and water/steam flow)control flow chart and step7 ladder diagram.Through the cooperative operation of the above-mentioned programs,not only the automatic operation of the main system of the extruder can be realized,but also the process parameters in the production process can be collected.Online real-time control and system program debugging can be carried out.(5)Finally,I analyze the requirements of the upper-level monitoring system and design the function structure tree of the system.Then I use Win CC to complete the function and screen design of the monitoring system.It can meet the requirements of the production process and display the production process parameters and system work status in real time after debugging.