转炉齿轮传动系统裂纹动力学特性及诊断方法研究

Research on dynamic characteristics and diagnosis method of cracks of converter's gear transmission system

当前针对全悬挂转炉倾动装置的动力学行为研究,多采用集中质量模型研究其扭转特性,而忽略系统横向弹性引起的弯扭耦合效应。此外,超低速重载运行环境下,系统齿轮故障动力学机理及诊断方法亟需深入研究。为此,首先基于拉格朗日方程法建立了转炉倾动装置多点啮合齿轮传动系统弯扭耦合动力学模型;其次,考虑裂纹引起的时变刚度特性,建立了含裂纹故障倾动装置动力学模型;然后采用Newmark-β法对正常及裂纹故障下的动力学响应进行求解。结果表明:当存在裂纹时,时域响应出现因裂纹引起的明显冲击,对应频域出现幅值极小的边频带,然而由于裂纹故障特征的微弱性,此特征容易被淹没在噪声中,难以诊断。因此,最后考虑现场噪声干扰,提出了改进的多点最优最小熵反褶积包络谱法,通过对比直接包络谱法,其故障包络谱能量占比提高了8.4倍,显示了该方法的优越性和有效性。本研究为转炉倾动装置齿轮裂纹动力学机理及诊断提供了理论依据和方法参考。

Currently,most studies on the dynamic behavior of the fully-suspended converter's tilting device adopts the model of concentrated mass,in order to explore its torsional characteristics,while ignoring the bending-torsion coupling effect caused by the system's lateral elasticity.In addition,in the operating environment of ultra-low speed and heavy load,both the dynamic mechanism and the diagnosis method which are specifically used for the system gear faults call for in-depth study.Firstly,as for the converter tilting device,the bending-torsion coupling dynamic model of the multi-point meshing gear's transmission system is set up by means of the Lagrange equation.Secondly,with the time-varying stffness characteristics caused by the cracks into consideration,the dynamic model of the tilting device with the crack faults is set up.Then,the Newmark-βmethod is used to solve the dynamic response under normal conditions and with the crack faults.The results show that when there are crack faults,there is a significant impact caused by the cracks in the time-domain response,corresponding to a very small amplitude sideband in the frequency domain.However,the crack faults are weak,which are easy to be submerged in noise and dfficult to diagnose.Therefore,with the interference of on-site noise taken into account,an improved multi-point optimal minimum entropy deconvolution envelope spectrum method is proposed.Efforts are made to compare this method with the direct envelope spectrum method.It is found that the proportion of energy obtained from the fault envelope spectrum increases by 8.4 times,which has verified that this method is superior and effective.This study provides theoretical basis and methodological reference for the dynamic mechanism and diagnosis of gear cracks in the converter's tilting device.