111 超音波法による転がり軸受の潤滑診断の可能性(セッション3 状態監視(2))

Abstract

Evaluation of a lubrication condition of ball bearing becomes an important issue for safe operation of a machine. In this paper, an application of ultrasonic technique is attempted for a purpose of evaluating the lubrication conditions. Quantitative measurement of a dent size which forms the origin of flaking is important for an evaluation of lubrication conditions. The width of indentation having 0.45mm on a raceway surface of an inner ring becomes possible with the observation of the change in echo height reflected from a boundary surface between housing and outer ring of the ball bearing. Furthermore, it can be possible to evaluate an insufficiency of oil in ball bearing by the observation of reflection echo height variation from a contact surface of outer ring and ball. When a sufficiently oil is supplied to the inlet of contact surface between them, the echo height increases locally. However, degree of its increase becomes lower when oil supply is insufficient, and does not appear at all with running out of oil. A time lag between the bottom of valley in echo height variation and the sound axis of ultrasonic probe decreases gradually as supply of oil becomes insufficient, and it becomes zero by running out of oil at a contact surface.