Non-intrusive measurement of strip thickness and roll-bite length in metal rolling

It is important to monitor the rolled strip thickness standard to minimize material waste and loss of profit due to strip flatness defects, and also to maintain the product’s size and dimensional homogeneity. Several online measurement techniques are available but none of this can give an in situ measurement within the roll bite. Due to this, a novice experimental method utilizing ultrasonic reflection sensor mounted on one roll was developed for in situ measurement of strip thickness and roll-bite length during cold rolling process. A pitch–catch method was used whereby a piezoelectric element generated an ultrasonic pulse and transmitted to the contact interface evaluated on a pilot mill. The reflected signal was captured by a second piezoelectric element and analysed to determine the condition at the strip–roll interface. This approach was implemented on a pilot mill and reflections from various locations in the roll bite during the rolling were recorded. Recorded signals were used to estimate the rolled strip thickness and roll-bite length after the rolling process.