Pattern Formation Phenomena Generated in Steel Making Machines and Automobiles and Its Countermeasures

1.根据废弃轧辊的板形测量结果，在周向上，随着轧辊位置的不同，多边形数也不同。确认与第一模式(旋转模式，47.5赫兹)相关联的37个多边形和与第二模式(线性模式，63赫兹)相关联的49个多边形出现在卷轴上。通过对热矫直机在运行过程中的振动测试，证实了随着磨损量的增加，有选择性地出现了特定的频率分量，在测量时刻出现了热矫直机第二固有频率的唯一分量。建立了刚体(上部单元)通过轧辊与平板接触的两自由度分析模型，并考虑了磨损的滞后效应，对多边形磨损进行了分析。结果表明，实际加工过程中的现象与数值分析结果吻合较好。即使改变轧辊的转速和矫直机的固有频率，也不可能从根本上防止多边形磨损。对具有磨损时滞的系统进行了模态分析，得到了各阶振型的运动方程，并得出了一些重要的参数。对该系统的特征根进行了解析近似处理，并与精确解进行了比较，研究了参数对斑图形成现象的影响。采用数值模拟的方法，研究了小幅改变运行速度的对策。结果表明，交替改变两种运行速度可以延缓花纹的生长速度。研究了运行速度的最佳变化方法。

1. According to the shape measurement of abandoned rolls, the polygonal number varies by roll position in the circumferential direction. It is confirmed that 37-polygon associated with the first mode (rotation mode, 47.5Hz), and 49-polygon associated with the second mode (linear mode, 63Hz), occur on the rolls.2. According to the vibration measurement of the hot leveler in operation, it was confirmed that a specific frequency component appeared selectively as the polygonal wear grew, and the only component of second natural frequency of the hot leveler appeared at the measuring time. This means the only 49-polygon associated with the second mode grew on all upper rolls.3.A two degree-of-freedom analytical model was presented in which a rigid body (the upper unit) vibrates in contact with a plate through the rolls, and was analyzed the polygonal wear taking the retardation effect of the wear into account. As the result, a good agreement between the phenomena in the actual machine and the numerical analytical results was confirmed.4. It is impossible to essentially prevent a polygonal wear, even if we change the rotating speed of the rolls and the natural frequency of the leveler.5. 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.6. 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 the operation speeds was also studied.