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现代高速带材轧制中经常出现一种异常的运行工况——轧机颤振,同时产品表面出现周期横向条纹,近年某厂从日本引进的1600高速铝带轧机亦有类似问题,以致难以生产高精度带材。它是当前轧制领域中急待解决的难题。作者根据产品表面印痕特征与统计规律,对轧机横向振动进行了系统研究: ·在线采集轧机系统输入输出信息; ·用瞬态激振与计算方法研究轧机固有动态特性; ·运用相关与自谱分析识别轧机振动的统计规律; ·运用互谱与互相关分析进行振源的识别。由此得出对1600轧机横向振动及产品表面印痕的某些认识: ·1600轧机稳态轧制中同时存在轧机横向振动与传动系统扭振,在其固有频率与激振频率异常接近的几个频带出现共振响应,并直接导致产品表面印痕,其中600Hz高频垂振共振响应频率是产品印痕主频率。·垂振振源为主电机电源中50Hz各阶倍频交流分量,控制系统的“双环”增强了这种干扰,振源通过基础激励与回转-垂直耦合激励轧机垂振。最后,提高了改善现有轧机动态特性与抑制、减轻产品印痕的对策: 1.增强供电系统滤波功能,增大平波电抗器容量,以清洁电源。 2.在控制回路的速度闭环中串接一个二阶微分校正网络,消除机电系统低频振荡;在电流闭环中设置窄带滤波器,消除机电系统高频振荡。 3.调整润滑剂极性,增强油膜抗振能力。对新设计轧机,为获得良好动态特性,应对机、电、液、气、工艺进行大系统动态优化设计。
In modern high-speed strip rolling, an abnormal operating condition, such as the flutter of the rolling mill, and the periodic horizontal stripes appear on the surface of the strip. In recent years, there is a similar problem with a 1600 high-speed aluminum strip mill introduced from a factory in Japan so that it is difficult to produce High-precision strip. It is an urgent problem to be solved in the current rolling field. The author systematically studied the rolling mill lateral vibration according to the characteristics of the impression on the surface of the mill and the statistic rules: · Collecting the input and output information of the mill system online; · Studying the inherent dynamic characteristics of the rolling mill by transient excitation and calculation; · Correlating and auto- Identify rolling mill vibration statistical rules; Use cross-spectrum and cross-correlation analysis of the vibration source identification. From this, we can get some knowledge about the transverse vibration of 1600 rolling mill and the impression on the surface of the mill: · In the steady rolling process of 1600, there are both the transverse vibration of the rolling mill and the torsional vibration of the transmission system. When the natural frequency and excitation frequency are very close Resonance response appears in the frequency band, and a direct result of the product surface imprint, of which 600Hz high frequency vertical resonance response frequency is the main product imprint frequency. · The vertical vibration source is the 50Hz step-frequency AC component in the main motor power supply. The “double loop” of the control system enhances this interference. The vibration source vibrates the vertical vibration of the rolling mill through the basic excitation and the swing-vertical coupling. Finally, the measures to improve the dynamic characteristics of existing rolling mills and to suppress and reduce the impression of products are improved: 1. Enhance the filtering function of the power supply system and increase the capacity of the smoothing reactor to clean the power supply. 2. Connect a second-order differential correction network in the speed loop of the control loop to eliminate the low-frequency oscillation of the electromechanical system; set the narrow-band filter in the current closed loop to eliminate the high-frequency oscillation of the electromechanical system. 3. Adjust the polarity of lubricants, oil film to enhance vibration resistance. For the new design of rolling mill, in order to obtain good dynamic characteristics, we should make great systematic dynamic optimization design for machine, electricity, liquid, gas and craft.