热轧过程中摩擦系数非对称性对轧机振动及稳定性的影响

Influence of friction coefficient asymmetry on vibration and stability of rolling mills during hot rolling

建立了摩擦系数非对称性的轧制过程模型,并与某热轧机传动系统的垂直-水平-扭转结构模型相结合,建立了结构-过程相耦合的动力学模型.利用稳定性准则确定了摩擦系数非对称作用下轧机系统的稳定域,分析了摩擦系数的非对称性对轧机系统振动特性和稳定性的影响规律.通过仿真分析表明,摩擦系数的非对称性对系统的稳定性有显著的影响,随着非对称程度的不同,系统会出现稳定域、水平失稳域和水平扭转失稳域,不同程度的非对称性会造成不同的振动形态.通过对某热轧厂现场测试,得到了轧机系统的振动信号,验证了仿真分析的正确性,同时指出轧制集装箱板和普板(Q235)时的变形抗力不同引起稳定域的差异,从而使得在摩擦系数的非对称程度一样时,轧制集装箱板时落在了水平失稳域,系统出现了明显的水平振动;轧制普板(Q235)时落在了稳定域,系统没有明显的振动.

The modern rolling industry has improved product quality, and the technical requirements of high accuracy and high dynamic performance have made the issue of rolling mill vibration more prominent. Rolling mill system instability seriously affects the quality of the product, reduces the accuracy of the product, and even causes serious damage to the rolling mill equipment. During hot rolling process, friction is of great importance to vibration and stability of the rolling mill. There is a difference in the friction coefficient between the upper rolling interface and lower rolling interface. Considering the asymmetric friction coefficient, a chatter model was established by combing the rolling process model and the vertical-horizontal-torsional structure model of a hot rolling mill to study the relationship between friction coefficient asymmetry and stability of the rolling mill system. According to the mathematical model, the friction coefficient stability domain of a rolling mill system is determined by the application of stability criterion. And it shows that the influence of the asymmetric friction coefficient on the stability domain is significant. Due to the different degrees of asymmetry, the system is divided into stable domain, horizontal instability domain, and horizontal-torsional instability domain. As the asymmetry in terms of the friction coefficient becomes considerable, it would occur various vibration modes. Through a field test of a hot rolling mill, the vibration signal of the rolling mill system was obtained, which verified the correctness and validity of the simulation analysis results.The degree of asymmetry in the friction coefficient is the same when rolling the container plate and the Q235 plate,but the deformation resistance of the system is different.The system falls into the horizontal instability domain when the container plate is rolled,displaying clearly horizontal vibration.However,the system falls into the stable domain when the Q235 plate is rolled,and the system shows no obvious vibration.