Device for detecting thickness fluctuations in cold-rolled metal sheets

摘要

The invention relates to a device for detecting thickness fluctuations in cold-rolled metal sheets. These occur periodically and generally have complex causes. The prior proposals for measurement and circuitry do not yield an expression sufficiently free of inertia, with the result that the automatic logging, referred to the strip length, of the said thickness fluctuations is still not possible. According to the invention, this is achieved by the sensors which differentially detect thickness fluctuations in terms of amplitude and frequency and whose signals are processed in an evaluation circuit in which there is an adjustable trigger threshold which enables a sample and hold stage to be controlled as a function of the measurement signal in such a way that the influence of the disturbing, non-periodic signal components is largely avoided, whereas virtually the entire information of the measurement signal which stems exclusively from thickness fluctuations of a periodic nature is retained.