The Analysis Of Roll Eccentricity Based On Thickness Error Tracing

With the rapidly development of society, people have an increasing demanding onthickness precision of the plate which is the main iron and steel products and take animportant part in the national economy. The roll eccentricity which is caused by irregularshape of the roll body and poor assembly accuracy is a more complex periodic motion. Agreat deal of experiments shows that the higher the accuracy of rolling, the precision effectof roll eccentricity will be greater.Cold rolled strip control system is a multi-variable control process. Roll eccentricityare reflected in the various variables, which is difficult to extract the eccentricity signalaccurately from a single information source. Our research adopted the roll eccentricityanalysis method based on thickness difference tracing, extracted accurate eccentricaccording to comprehensive data containing the roll eccentricity signal sequence andconducted compensation research.Firstly, we analyzed the reason of roller eccentricity produces and the influence ofrolling mill thickness and established a comprehensive data contains the roll eccentricitysequence, which provide conditions for the extraction of eccentric signal. As the rollingspeed change frequently in the rolling process, we put forward a sequences transitionmethod, which can transfer the time series into strip length sequence, meanwhile,eliminate the influence of speed fluctuation.Secondly, the algorithm of the time frequency analysis of thickness difference tracingwas introduced. Because the resolution of the wavelet analysis is poor when deal with thehigh frequency detail, we proposed wavelet packet for the roll eccentricity signaldenoising. According to wavelet packet frequency interleaving phenomenon, wesummarized the reasons and obtained the right corresponding band relationship.Thirdly, based on experiments conducted in a school of300rolling mill and analysisof a large amount of historical data on the mill produced, we utilized wavelet packetanalysis to obtain the eccentricity signal,compared with the eccentricity signal extractionof no-load pressed and verified the accuracy of the eccentric signal. Finally, according to the phase position, we took advantage phase informationcontained by the rolling force signal to correct the eccentricity signal source and verifiedby simulation that this method can accurately locate the eccentricity signal. Aiming at theproblem that traditional PID control static error can eliminate the periodic signal, weproposed a new compound control method based on PID and repetitive control, thesimulation results of which show that the composite control method is effective.