Self-oscillation of the tension stations of an etching unit combined with the tandem cold-rolling mill 2000

On multi-cage cold rolling mills combined with a continuous etching unit, self-oscillations can occur not only on the mill stands but also on the tensioning stations of the etching unit. Fatigue cracks can appear on the rollers of the tension stations, and characteristic defects can appear on the surface of the polyurethane-coated roller. To measure self-oscillations, MEMS accelerometers are installed on the roller bearing supports. The collection of vibrational data takes place in parallel with the measurement of technological parameters. Time series databases are used for data storage. The hybrid database allows the simultaneous processing of technological and vibrational parameters. When an emergency situation occurs, it is possible to chart the dependence of self-oscillations on the technological parameters. Using the results of an industrial experiment, it was possible to obtain the characteristic of the friction of the rolled strip on the roller of the tension station at low strip movement speeds. At band speeds from 0.5 m/s to 1 m/s, the friction characteristic is in a transient mode and can be either positive or negative. With a negative characteristic of friction, self-oscillation appears, with a positive characteristic, the movement of the belt stabilizes. Signal processing was carried out using Fast Fourier Transform (FFT). According to the spectral characteristic, it is possible to determine the number of complete cycles acting on the oscillatory system. Having a sufficient amount of information in time, it is possible to calculate the number of cycles and estimate the residual resource before cracks appear on the end surfaces of the roller of the tensioning station.