Contactless flatness measurement

The increasing demands on the quality of cold-rolled strip place a growing requirement on good flatness. However, the strip flatness is not only one of the most important quality factors of rolled strip, it is also of vital importance to the rolling process since flatness errors lead to non-uniform distribution of tension stresses across the strip width. As this can lead to strip breaks in many cases, a reliable measurement of the strip tension distribution is necessary. The strip tension stress distribution across the strip recorded during rolling is a measure of the flatness of a cold-rolled strip. This tension distribution is recorded during rolling and displayed by the flatness measurement system. The flatness control has the task of setting the required strip tension stress distribution, whereby the roll gap is matched to the strip profile as far as possible. Various actuators are available to the flatness control for this purpose. Siemens newly developed contactless flatness measurement device is working on a contact-free principle. The main parts of the measurement are an actuator which excites the strip to an oscillation and a sensor line for the reception of the tension distribution. The principle of the measurement and the results of first successful implementations are presented.