Study on Work Roll Vertical Vibration Under Periodic Spalling of the Oxide Film

Abstract

The dynamic effect of work-roll oxide-film periodic spalling on vertical vibration in a hot strip rolling mill was studied. Based on dynamic monitoring test analysis, the friction of the work-roll surface under oxide-film periodic spalling is discussed. Using an average rolling pressure formula, the rolling force under the dynamic vertical vibration and the time-varying friction coefficient were found. A two-degrees-of-freedom dynamic system of the hot strip mill was established, considering the roller system symmetry. Based on the multiscale small-parameter perturbation method, the main resonance characteristic of work-roll vertical vibration has been explored. Using the 1780-mm hot strip mill in Chengde Iron and Steel Co., Ltd., the dynamic characteristics of the system are analyzed when oxide-film periodic spalling occurs on the work roll. The results are consistent with the test data, which show the effect of oxide-film spalling on vertical vibration. The simulation results for resonance characteristics show that the vibration of the system can be effectively reduced by increasing the damping and adjusting the stiffness of the system. In rolling production, it is very important to ensure the stability of the oxide film in order to reduce fluctuation. This study provides a reference for the operation and maintenance of a rolling mill in the strip production process.

Keywords:

• Hot rolling mill
• oxide film
• vertical vibration
• time-varying friction coefficient

Additional information

Funding

The authors are grateful for the support of the National Key R&D Program of China (no. 2017YFB0304103), the Regional Joint Development Fund (no. U20A20289), the Key Projects of Natural Science Foundation of Hebei Province (no. E2017203161), and the Innovation Funding Project for Graduate Students in Hebei Province (no. CXZZBS2020054).