Research On Collaborative Vibration Mechanism And Control Of Tandem Cold Rolling Mill

The research on suppression control of vibration in tandem cold rolling mill is a big problem in the rolling field.When vibration occurs,there is a synergistic vibration phenomenon throughout the entire unit.Previous understanding and research on this phenomenon are gradually deepening,but it is not clear enough and there is no universally recognized conclusion.The 1450mm tandem cold rolling mill was used as the research object in this thesis.First,the vibration process of the rolling mill was monitored and analyzed,and it was found that the rolling mill vibration is closely related to the incoming strip steel;Then,based on the rolling mill drawings and data,a dynamic model of a single stand rolling mill system was established and simulated.The amplitude frequency characteristic of the rolling mill system were examined,and the possible regions and ranges of vibration frequency band of the rolling mill system were obtained.The multi factor influencing mechanism of vibration amplitude and frequency was explored;Finally,a global dynamic model of the tandem cold rolling mill was established,and in-depth research was conducted on the effects of various factors,resulting in some innovative conclusions.Based on these findings,vibration suppression measures were proposed and applied on site,achieving good vibration suppression effects.The specific research contents are as follows:(1)To address the vibration problem of the 1450mm tandem cold rolling mill,a vibration online monitoring system for the entire unit has been developed and put into operation.The vibration signal was collected by using the vibration speed sensor at the top of the memorial archway of five rolling mills and the torque measuring device on the output shaft of the drive motor.The function of online time domain and frequency spectrum automatic display was realized,and the running status of the rolling mill can be observed at any time.When the rolling speed reached about 200 m/min and 1200 m/min,the collaborative vibration phenomenon with the main frequency of 18 Hz and 109 Hz respectively occurs.(2)Based on the drawings and materials provided on site,a dynamic model of a single stand rolling mill system was established and verified.The amplitude frequency characteristics of each rolling mill mechanical system and electromechanical coupling system were obtained through harmonic response analysis.The influence mechanism of thickness difference control system and speed control system on rolling mill vibration was analyzed,and the following conclusions were obtained:the vibration amplitude of the rolling gap was increased by the vibration of the work roll due to the effect of the strip thickness control system in the resonance zone.The motor speed control system changes the resonant frequency of the drive system by affecting the mechanical characteristics of the motor.(3)Based on the dynamic model of a single stand and the coupling relationship between stands,a global dynamic model of the tandem cold rolling mill was established.The effects of strip thickness inheritance,strip tension,and second flow control on the coordinated vibration of the mill were explored and analyzed.The main factors and laws inducing vibration of the mill were obtained.When the rolling speed was 1200m/min,under the influence of strip thickness inheritance and tension,all rolling mills vibrated at 109Hz and gradually amplified,ultimately resulting in the outlet thickness difference of the finished strip reached more than ten times the inlet thickness difference,thereby formed obvious vibration marks.When the rolling speed was 200m/min,the transmission system of S1 rolling mill was subjected to the maximum speed fluctuation excitation at the given speed end through the control of second flow rate and the influence of speed chain,ultimately exhibited the strongest torsional vibration.(4)Based on on-site testing,theoretical research,and simulation analysis,specific feasible measures for suppressing collaborative vibration of cold rolling mills were determined,and the vibration suppression effects were compared with those of adjusting controller parameters and filtering parameters.The results showed that the vibration suppression effect of active vibration suppression and electromagnetic damping vibration suppression control technique was more obvious,providing a new solution for collaborative vibration of tandem cold rolling mills.