Pattern Formation Phenomenon Accompanied by Wear Generated in Rotating Contact Systems and Its Countermeasures

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This investigation deals with the guidance to the initial design of the hot leveler of a steel making machine to prevent the polygonal wear of work rolls, the delay measures of the growth speed of the pattern by changing operating speeds and a countermeasure by using dynamic absorbers. The results obtained are summarized as follows :(1)The modal analysis was applied to the system with time retardation by wear in order to obtain the equations of motion for each mode and some important parameters were derived. The characteristic roots of this system were treated analytically and approximately and the influence of the parameters for pattern formation phenomena was investigated, compared with the exact solutions.(2)The countermeasures by changing the operating speed in a small way were studied by applying numerical simulation. As the results, it was confirmed that the growth speed of the pattern could be delayed by changing two operating speeds alternately. The optimum changing method of t … More he operation speeds was also studied.(3)The authors discussed the optimal design of dynamic absorber mounted on a single degree-of-freedom system where the polygonal wear phenomena are generated. They obtained the characteristic root approximately, and applied the optimal design procedure (optimal tuning, optimal damping) of dynamic absorber for forced vibration of a single degree-of-freedom system to this self-excited vibration system. As the result, they obtained a design in which the system was stabilized perfectly.(4)The result mentioned above was applied to a hot leveler as a two degree-of-freedom system through the modal analysis. As the result of numerical analysis, the hot leveler was changed into a perfectly stable system by two dynamic absorbers for the first and second vibration modes, and the polygonal wear phenomena were not generated at all.(5)The optimal design procedure of the dynamic absorbers for preventing the polygonal wear of work rolls perfectly is very simple and effective and the designer of the hot leveler can use it easily. Less