Advanced roll gap sensors for enhanced hot and cold rolling processes (ROLLGAP SENSORS) : final report

5 different roll gap sensors were designed, manufactured and implemented in work rolls for laboratory, pilot and industrial tests in hot and cold rolling conditions. Three friction sensors for roll-strip contact stress evaluation can cover a wide range of rolling conditions: the pin friction sensor is able to evaluate longitudinal and transverse bite friction but it heavily marked the strip while the measured shear stresses were not correct. The Rollsurf friction sensor also marks the strip but the measured shear stress seems correct and it is insentitive to temperature so suitable for hot rolling conditions. The indirect friction sensor does not mark the strip. It has also the possibility to sustain high roll forces of cold rolling conditions (impossible with the two other friction sensors). But it is only able to evaluate correctly normal contact stresses. One lubrication sensor was tested successfully in cold rolling conditions to determine the respective contribution of lubricant and roll-strip solid contacts to sustain the rolling load. Combined with a lubrication model and the knowledge of lubricant compressibility, the sensor can estimate the oil film thickness profile. One temperature sensor with inverse calculation can evaluate correctly heat transfers in the roll bite for low rolling speeds. For higher rolling speeds, the sensor under-estimates the peaks of temperature and heat flux in the bite. It was however successfully used to evaluate roll temperature evolution on one hot strip mill finishing stand. This information is used to analyse thermal fatigue and adapt roll cooling strategy by simulation.