Design And Realization Of The Single Screw Extruder Temperature Control System Based On Fuzzy Control

The research is based on the cooperation project with Ji Lin spinning Institute, mainly to control the temperature of the spinning process. In the spinning industry, the main steps of spinning contain: the heating and molten of the fiber-forming polymer in screw extruder, the melt flows through the metering pump and extruded from the nozzle hole to form fiber trickle, cooling solidification of the melt trickle, oil and winding the thin fiber, stretched thinner to form the finished fiber product. The melt viscosity and temperature is the main technological parameters of melt spinning. Under certain temperature condition, the melt viscosity is mainly depends on the molecular quantity of the fiber-forming polymer. The melt temperature can be controlled by all paragraphs temperature of the screw extruder, the melt temperature too high, can lead to degradation of polymer and formation of air bubbles; Too low, will lead to high melt viscosity, make the flow uneven and easy to produce silk wool and fiber cracks, and so on, during fiber stretching; Both cases can’t form normal spinning process. So, shows the importance of the temperature control.The temperature controller this paper described is design to control the heating power of the single screw extruder. The single screw extruder used in the spinning Institute have seven segment of heating zones, respectively, zone one to zone five, the Flange zone and Die zone, which influence each other in temperature.This paper described the design process of the temperature controller. Firstly, it briefly introduced the significance of the research and the present situation at home and abroad about this topic; then it described the overall framework of the whole system, and gave the overall construction of the hardware circuit. After that it introduced the construction of the hardware circuit of each module in detail, mainly contain micro controller-STM32 module, temperature sampling module, power module, communication module and power control module, etc. The specific implementation process: the heating part of the temperature sampling measurement module adopts the seven section heating furnace of the single screw extruder. Using the platinum resistance temperature sensor and max31865 to sampling measurement the temperature of the furnace, then, give the digital resistance value to the temperature controller for fuzzy calculation. Then give the calculation result to a D/A converter to convert the digital signals into analog signals. Because signal transmission used the current transmission, so need a voltage to current converter to get the current signal, then use the obtained 4-20 m A current to control the thyristor conduction angle, and eventually achieve the purpose of control the heating power and regulate the temperature. After that, it introduced the produce and application of the fuzzy control theory, and details of the design process of the fuzzy controller. Finally give the flow chart of software and the experimental data in laboratory test and the experimental data of industrial test.The temperature controller has been applied in Ji Lin spinning Institute, has the characteristics of stable operation, reliable performance, good robustness and so on. At the same time, the equipment is improved in three aspects compared to the original temperature control equipment that used in the spinning institute, the first is in the display, replace the large volume of temperature control cabinet instrument display with a small size liquid crystal display; Second is improved the control precision, the original equipment uses PID control, but, this equipment uses fuzzy control; Finally, the transition time is improved, from the original 4 hours to 2 hours, shorten the time to a half, improved the working efficiency, meet the acceptance criteria of the project.