Novolipetsk Iron and Steel Works, Lipetsk, Russia:

V. A. Pimenov, Cand. Eng., Head of Technological Projects of the Directorate for Development of New Process Technologies, e-mail: pimenov_va@nlmk.com

Abstract: A retrospective review of studies of the problem of vibrations (chatter) during highspeed cold rolling at the five-stand mill 2030 of the Novolipetsk Iron and Steel Works, as well as the results of operation of vibration diagnostics and speed control systems at the mill, is presented. As part of the continuation of research on the 2030 mill, a series of experimental rolling of thin strips with chatter provocation was carried out, a statistical analysis of the dynamics of technological parameters and vibration accelerations of the roll chocks in time and frequency (spectral) representations was performed. It is shown that the reason for the development of the chatter is the mutual synchronization of vibrations of stands at the frequency corresponding to the natural frequency of the vertical vibrations of the housing posts stretching. The dynamics of the oscillations phases ratio of the stands has been studied and it has been established that when the frequencies are synchronized and the phases of neighboring stands coincide, the amplitudes of their oscillations increase sharply, indicating the beginning of the chatter. A criterion for violation of the stability of the rolling process is proposed, which makes it possible to diagnose the critical level of vibrations and the moment of occurrence of the chatter. A mathematical model of vibrations of the stand during rolling is presented, taking into account the nonlinear damping of the dynamic deformation zone, on the basis of which the dependence of the amplitude of synchronized vibrations of the stand on the magnitude of disturbances and technological parameters is obtained using the Van der Pol method. The adequacy of the relation obtained was confirmed during a series of experimental rolling with varying technological parameters, which made it possible to increase the maximum rolling speed without the chatter to 25%. The results obtained can be used to stabilize the technological process and increase the productivity of cold rolling, when creating systems for diagnosing vibrations and controlling continuous mills.

NLMK workers A. V. Morozov, N. A. Dikarev, Yu. K. Slaby, A. V. Litvinov, Yu. A. Tsukanov, M. E. Orekhov, et al took part in carrying out the experimental rolling.

1. Markworth М. Cross waviness of cold rolled strip. Chernye Metally. 1995. No. 4. pp. 50–59.
2. Asit K. C., Vinay S. G., Rahul K. V. A Review on chatter analysis in cold rolling process. Juniper Online Journal Material Science. 2017. Vol. 2. No. 1. pp. 1–6.
3. Mosayebi M., Zaminkolah F., Farmanesh K. Calculation of stiffness parameters and vibration analysis of a cold rolling mill stand. International Journal of Advanced Manufacturing Technology. 2017. Vol. 91. No. 9. pp. 4359–4369.
4. Usmani N., Kumar S., Velisatti S., Tiwari P., Mishra S., Patnaik U. Chatter detection using principal component analysis in cold rolling mill. Diagnostyka. 2018. Vol. 19. No. 1. pp. 73–81.
5. Heidari A., Forouzan M. R., Niroomand M. R. Development and evaluation of friction models for chatter simulation in cold strip rolling. International Journal of Advanced Manufacturing Technology. 2018. Vol. 96. No. 2. pp. 2055–2075.
6. Niroomand M. R., Forouzan M. R., Heidari A. Experimental analysis of vibration and sound in order to investigate chatter phenomenon in cold strip rolling. The International Journal of Advanced Manufacturing Technology. 2019. No. 100. pp. 673–682.
7. Bocharov V. F., Bocharov V. V., Bocharov D. V. On vibrations of the equipment of working stands of continuous cold rolling mills in the production of strips of thin gauge. Stal. 2019. No. 12. pp. 45–47.
8. Kozhevnikov A., Kozhevnikova I., Bolobanova N., Smirnov A. Chatter prevention in stands of continuous cold rolling mill. Metallurgy. 2020. Vol. 59. No. 1. pp. 55–58.
9. Kozhevnikov А. V., Yusupov V. S. Methodology for designing the cold rolling technology that eliminates vibrations in mills. Stal. 2021. No. 5. pp. 21–24.
10. Rumyantsev М. I., Shubin I. G., Gorbunov А. V., Lukyanov S. А. et al. Evaluation of causes and development of measures to overcome the instability of cold rolling on a OJSC MMK`s continuous mill 2000. Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta imeni G. I. Nosova. 2014. No. 2 (46). pp. 30–36.
11. Kolpakov S. S., Pimenov V. A., Tsukanov Yu. A., Rubanov V. P. Study of vibrations at 2030 mm five-stand mill. Steel in Translation. 1993. No. 1. pp. 47–52.
12. Pimenov V. A., Kolpakov S. S., Tsukanov Yu. A., Rubanov V. P., Skopintsev V. V. Automatic diagnosis of vibrations and control of the speed regime on the 2030 mill. Steel in Translation. 1999. No. 10. pp. 47–52.
13. Garber E. А. Production of rolled products: reference book. Vol. 1. Book 1. Production of coldrolled strips and sheets. Moscow: Teplotekhnik, 2007. pp. 169–182.
14. EN 10130. Cold rolled low carbon steel flat products for cold forming. Technical delivery conditions. Berlin: Deutsches Institut für Normung, 2007.
15. Blekhman I. I. Synchronization in science and technology. Moscow: Lenand. 2015. 440 p.
16. Hamming R. W. Digital filters. Moscow: Nedra, 1987. 221 p.
17. Andronov А. А., Vitt А. А., Khaykin S. E. Oscillation theory. Moscow: Nauka. 1981. 916 p.
18. Kotsar S. L., Tretyakov V. А., Tsuprov А. N., Polyakov B. А. Dynamics of rolling processes. Moscow: Metallurgiya. 1997. 255 p.
19. GOST 16523–97. Rolled sheets from quality and ordinary carbon steel for general purposes. Introduced: 01.01.2000. Moscow: Izdatelstvo standartov. 1997.