2017 Volume 52 Issue 12 Pages 737-752
This report is described the study on the measurement of the oil film thickness between shaft and bearing in porous sintered oilless bearing as a DC spindle motor’s bearing system by using ultrasonic wave. Generally, the thickness of oil film generated between shaft and bearing is so thin that the direct measurement of its thickness is very difficult. Therefore, in this study, the ultrasonic method is proposed to measure the oil film thickness for the establishment of quantitative measuring. As a basic experiment, immersion ultrasonic technique is applied. Moreover, it is confirmed experimentally that there are approximately proportional relationship between the oil film thickness and the echo ratio of reflected ultrasonic amplitude. However, by the generation of heat at oil film under shaft rotating condition, the temperature of oil film and bearing are raised, and the measurement of the oil film thickness might become difficult because these acoustic properties are changed. Then, in this report, it is proposed to examine for the improvement in measuring accuracy with thermal correction system.
