Search Results (2)

The monitoring and control of residual stresses and microstructure are of paramount importance for the steel industry. Residual stress annihilation is needed during the entire lifetime of steels. In this paper, we presented a stress monitoring and annihilation method, based on a force sensor for stress monitoring and an induction heater for localized heat treatment and corresponding stress annihilation. The heat treatment results indicated an at least 90% reduction of localized stresses, allowing for the implementation of the method in steel production and manufacturing to improve steel quality and perform faultless steel production and manufacturing. Full article

We report on an optical sensor system attached to a 4 kW fiber laser cutting machine to detect cutting interruptions. The sensor records the thermal radiation from the process zone with a modified ring mirror and optical filter arrangement, which is placed between the cutting head and the collimator. The process radiation is sensed by a Si and InGaAs diode combination with the detected signals being digitalized with 20 kHz. To demonstrate the function of the sensor, signals arising during fusion cutting of 1 mm stainless steel and mild steel with and without cutting interruptions are evaluated and typical signatures derived. In the recorded signals the piercing process, the laser switch on and switch off point and waiting period are clearly resolved. To identify the cutting interruption, the signals of both Si and InGaAs diodes are high pass filtered and the signal fluctuation ranges being subsequently calculated. Introducing a correction factor, we identify that only in case of a cutting interruption the fluctuation range of the Si diode exceeds the InGaAs diode. This characteristic signature was successfully used to detect 80 cutting interruptions of 83 incomplete cuts (alpha error 3.6%) and system recorded no cutting interruption from 110 faultless cuts (beta error of 0). This particularly high detection rate in combination with the easy integration of the sensor, highlight its potential for cutting interruption detection in industrial applications. Full article