グリース潤滑された玉軸受の異常振動 : 第1報, 異常振動の発生に及ぼすグリースの種類の影響

Abnormal vibration of a ball bearing lubricated with grease was studied. The test bearing was lubricated with three types of grease such as Li soap/silicone oil grease, Na soap/mineral oil grease and Li soap/mineral oil grease. In the experiment, the axial-loaded ball bearing was operated at a constant rotational speed, and the vibration and the temperature of the test bearing were measured. In addition, the shear stress and shear rate of the grease was measured by using a rheometer. Experimental results showed that the abnormal vibration is observed on the test bearing lubricated with all three types of grease that were used in the experiment. On the basis of the experimental results, the generating mechanism of the abnormal vibration was discussed. From the discussion, it seems reasonable to conclude: (1) Li soap/silicone oil grease and Na soap/mineral oil grease have a negative damping moment characteristic. The abnormal vibration of the ball bearing lubricated with these greases is generated by the negative damping moment. (2) The abnormal vibration of the ball bearing lubricated with Li soap/mineral oil grease is generated by decreasing the positive damping moment of grease due to the rise in temperature.