Robust Temperature Control

CFSP - Brigham Young University - Figure 1 shows a weld that started in RPM control mode then given a temperature command 51°C lower than the current temperature.   The overshoot was 29%, rise time 3.325 seconds, 10% settling time of 17.3 seconds and 1°C settling time of 29.5 seconds. After the 1°C settling time, the temperature was held at 425°C with a standard deviation of 0.717°C for non-filtered temperature and 0.312°C for filtered temperature.   Welds were run using the same gains as the weld shown in Figure 1 in various plate thicknesses, commanded temperatures, backing plates and feed rates.  In all cases temperature control functioned properly and the commanded temperature was held with a standard deviation of less than one degree.   Similar results have been obtained for welds run using PCBN tools.