Application of Eddy Current Control in the Temperature Control Loop of the 3D Printing Process

Abstract

The paper is devoted to FDM 3D manufacturing. Most of the FDM 3D printers on the market use an indirect resistive nozzle heating method and standard thermoelectric temperature control methods, which leads to a high thermal inertia of the heating system and the inability to provide a sufficient speed and accuracy of temperature control. The inability to control the temperature of the nozzle during the printing process leads to inconsistent quality of layer-to-layer adhesion and on the larger scale - heterogeneity of the material inside the whole printed object. To mitigate and/or resolve these problems, an induction heating system of the nozzle with a minimum thermal mass is proposed. At the same time, a resonant (eddy current) method is proposed to control the temperature of the nozzle. High system power and low weight nozzle required the development of a new rapid control system.

A simulation model of the nozzle temperature control loop was created in the MatLab Simulink. The transfer functions of the induction heating system and the feedback circuit are determined.

The coefficients of the PID controller and its sampling period were determined. A zero static error and overshoot value of 1% eliminate overheating of the material during extrusion. The time for the system to reach the steady state is 1 s., that meets the requirements for rapid heating and cooling of the nozzle during the printing process.

The testbed system was created consisting of the ultra-low weight induction heated nozzle, a power source, a high-frequency oscillator, an inductor coil, a measuring coil, a unit for recording and processing a measuring signal. Experimental data for all stages of the conducted research is provided.