An accurate measurement method for center oil film thickness in high-speed roller bearing using ultrasound

A multicycle focal spot mapping method is proposed to design the specific pulse emission frequency and the recorded pulse number. A great number of successive ultrasonic pulses with a specific emission frequency are utilized to examine the lubricant film in the roller bearing so that at least one ultrasonic pulse will interrogate the center of the contact region. Subsequently, the center oil film thickness is calculated by the selected minimum ultrasonic reflection coefficient amplitude. A statistical test analysis and an experimental analysis are performed to validate the proposed method. The results show that the proposed method can be used to accurately measure the center oil film thickness in high-speed roller bearings, which overcomes the speed limitation of the existing method.