In Situ Diagnosis of a Gear-Tooth Surface Damage Using Laser Scattering

Abstract

We propose herein an in situ method to remotely diagnose gear-tooth damage using scattering of a laser beam. The proposed method provides early and accurate diagnosis of the gear-tooth-surface condition. A tooth surface is first irradiated at oblique incidence by a zone-covering laser beam, and the zone is scanned along the surface of the gear tooth by the rotation of the gear. By analyzing variations in laser scattering between benchmark data and the current data, we can estimate the condition of the gear-tooth surface in terms of abnormal abrasion, pitting, spalling, etc. To test the method, we used it to remotely detect gear-teeth pitting in an experiment during which we simultaneously measured the vibration and sound of the gearbox and pedestal. Our analysis shows that the laser-scattering measurements reveal pitting more clearly and at an earlier stage than does the vibration and noise measurements. Therefore, we conclude that the proposed method estimates the tooth-surface condition with sufficient accuracy to assess the lifetime of the gear. Furthermore, we used the proposed method to diagnose real gear-teeth in situ in practical gearboxes to verify that the method yields an accurate diagnosis of the tooth surface of a lubricated gear. We found that by attaching a cover to the laser receiver; the remote measurements were unaffected by the choice or method of lubrication. For force-feed lubrication, pitting was detected for every speed range under 1800 rpm. These results demonstrate that the proposed method can diagnose the tooth surface of lubricated gears in practical gearboxes. Finally, we developed an automatic damage diagnosis method that is capable of detecting pitting by analyzing the laser-scattering signal from damaged teeth combined with that from the same teeth prior to the damage.

Diagnosis of gear damage based on coefficient of variation method by analyzing vibration accelerations on one gear tooth

“…Therefore, it is crucial to detect the gear damage as early as possible. In the published reports, researchers have done countless effort to study the characteristics of gear failures and have developed many methods to detect gear failures, such as techniques of acoustic emission (Al-Balushi, et al, 2002, Toutountzakis andSamanta, 2005), stress wave analysis (Board, 2003), laser scattering (Tanaka, et al, 2011), vibration signal analysis (Feng, et al, 2001) and so on. According to the prior studies, analyzing the vibration signal has been proved to be one of the effective methods to diagnose gear conditions.…”

Easy set-up and in situ automatic gear diagnostic system using only laser reflection

“…However, it is still difficult to identify the location of the damage and provide a detailed estimate of its scale. To solve this problem, we developed a method that uses a laser beam for remote diagnosis (Tanaka, et al, 2011) and verified this method can diagnose gear tooth surface abnormalities on a lubricated gear in a practical gearbox. We also developed a real-time pit-detection Tanaka, Nakajima, Okabe, Takebe, Nagamura, Ikejo, Hashimura, Muramatsu, Watanuki and Nemoto, Journal of Advanced Mechanical Design, Systems, and Manufacturing, Vol.10, No.4 (2016) 59]…”

“…algorithm to create an automated gear-tooth diagnosis system (Tanaka, et al, 2011). Our method compares the measured laser reflection data and previous damage data or the mean data of all measured teeth.…”

Diagnosis for gear tooth surface damage by empirical mode decomposition in cyclic fatigue test

“…Consequently, failure diagnosis especially early detection of the gear damage is crucial to prevent the mechanical system from malfunction. Researchers have developed many techniques to detect gear faults using vibration signal (Koide, et al, 2013, Hood, et al, 2013, Lim and Mba, 2013, acoustic emission (Al-Balushi, and Samanta, 2002), tooth root strain (Board, 2003), laser scattering (Tanaka, et al, 2011) and so on. Especially, analyzing the vibration signal of gear motion is one of the most effective methods applied in the detection of gear failures.…”