高速动车组齿轮箱异常振动试验分析

Analysis of Abnormal Vibration Test for the Adjustment of EMU Gearbox

在分析齿轮箱振动特性的基础上，对其进行了振动模态试验和线路跟踪测试分析，找出齿轮箱箱体异常振动的根本原因。模态试验结果表明：齿轮箱的箱体模态最低为551Hz，其模态振型为扭转和弯曲的复合模态并以弯曲模态为主。通过线路振动测试结果可以看出，轴箱垂向振动加速度小于横向振动加速度，而齿轮箱振动正好与轴箱相反；从均方根的幅值大小来看，从轴箱到齿轮箱横向振动加速度的变化不是很大，但垂向振动加速度变化明显。齿轮箱上的垂向振动加速度均方根幅值是轴箱的2倍左右，这说明从轴箱到齿轮箱的振动传递存在放大现象。当运营速度接近300km／h时齿轮箱的振动加速度会急剧上升。通过相应的频谱分析发现齿轮箱的振动主频介于500-600Hz之间，非常接近齿轮箱的最低固有频率。这表明齿轮箱异常振动的根本原因在于轮轨上的高频激扰传递到齿轮箱上从而引起了结构共振。

Based on the analysis of the characters of gear- box abnormal vibration, a simulation experiment and an on - line test for the vibration are conducted to find the major reasons. The simulation result shows that the lowest modal of gearbox is 551Hz; the modal shape is mainly a mix of torsion and bending mode, while the on - line test results show that the acceleration of axle box orizontal vibration is smaller than vertical vibration acceleration, and the gear- box vibration is just the opposite. From the angle of RMS （root-mean-square） amplitude, the horizontal vibration acceleration has not obvious change from the axle box to the gearbox, but the vertical vibration acceleration changes obviously. The vertical vibration acceleration of gearbox housing is twice as much as that of axle box, it shows that the vibration is enlarged from the axle box to the gearbox. When the running velocity is about 300km/h, the gearbox housing vibration has a sharp rising. By analyzing the fre- quency spectrum of vibration, the main frequency is found between 500Hz to 600Hz, which is very close to the lowest natural frequency of gearbox housing. So the root cause of gearbox abnormal vibration is the resonance on gearbox housing, caused by the improvement of wheel/rail contact.