2017 年 52 巻 4 号 p. 229-240
When a bearing is set in a mechanical system, the external vibration and the change of load will occur due to its own rotation. In choosing of a rolling bearing under such an operating condition, the fatigue life is calculated by multiplying a dynamic equivalent load to a load factor, which corresponds to the operating condition, according to a corresponding standard. However, the load factor is sorted out into three categories and a quantitative condition to determine the load factor is not described in the standard. Since a designer of mechanical system tends to over-estimate the load factor for the sake of safety, it makes an excess specification, an enlargement in size and an advance in cost. Therefore in this research, endurance test of small rolling bearings were conducted with applying external vibration in radial direction with the aim of accurate determination of the load factor value. Consequently, in case of applied vibration acceleration less than 10m/s2, it was confirmed that the bearings rotated without abnormalities up to three times basic dynamic rated life. Meanwhile, it was observed that the wear at the loading area of outer raceway became larger with increasing vibration acceleration. Furthermore, it was also clarified that the external vibration had an influence on the damage of bearing raceway surface.