径向转向架DF8B机车垂向异常振动分析

针对DF8B机车采用引进径向转向架技术后出现的垂向振动加速度超标问题,分析比较机车实测振动频率成份和悬挂系统的频率响应特性,通过对悬挂参数和转向架结构的分析,确定产生这一问题的根源在于转向架随动式制动装置的布置方式,当轮对受到线路轨缝垂向冲击激励时,该装置的摩擦副不能顺畅滑动,使一系垂向弹簧两端瞬间形成刚性连接,导致机车产生非正常垂向振动。由简化模型计算表明,在摩擦副的作用下,机车车体的垂向频率响应发生了变化,在6 Hz有一个响应峰值,这就使机车8.4 Hz的一阶垂弯振动较易激起,如果去掉该摩擦副,则试验中得到的8.4 Hz的较大响应可望消除。

Abnormal Vertical Vibration Analysis of DF8B Locomotive with Radial Bogies

High level of vertical acceleration vibration far beyond specification requirements for DF8B locomotive equipped with GM self-steering bogie was measured during track testing.According to this problem,frequency components from testing are compared with simulation results in detail.Based on the study of suspension parameters and bogie structural characteristics,it is confirmed that the problem is caused by the arrangement of braking unit amounted on steering beam.When the wheelsets are under the vertical impact of rail gap,the friction pair of the equipment cannot slide smoothly.This makes the rigid joint come into being at the ends of the primary vertical suspension and cause the abnormal vertical vibration of locomotive.Analysis based on a simple model shows that,friction pair between braking unit and axle box will cause a 6 Hz car body response peak,this trends to result in 8.4 Hz car body bending modal vibration,which dominated in frequency response during track testing.It is expected to reduce the greater response 8.4 Hz obtained from track testing if the friction pair is removed.