Automated classification of wear particles based on their surface texture and shape features

A fatigue model for contacts under mixed elastohydrodynamic lubrication condition

Sliding–rolling contact fatigue and wear of maraging steel roller with ion-nitriding and fine particle shot-peening

This paper deals with health monitoring and evaluation of dynamic characteristics in gear sets. The wavelet transform (WT) is the method used for the time-frequency analysis. The dynamic characteristics of both steel and sintered gears were measured using a power circulating gear testing machine and were analysed in the time-frequency domain using continuous and discrete WTs. Furthermore, health monitoring of gear sets was carried out and tooth surface failure by pitting was diagnosed using WTs. The vibration acceleration characteristics of the gearbox could be divided into two different behaviours above and below the tooth mesh frequency. A failed tooth could be found by a change in WT intensity of the vibration acceleration, taking the tooth meshing into consideration. Since the discrete WT is able to provide the signal with the component of tooth mesh frequency, it was found to be superior to the continuous WT. In the case of failure at the dedendum surface of a driven gear, the amplitude of th...

Application of the wavelet transform to health monitoring and evaluation of dynamic characteristics in gear sets

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.

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

Surface Failure and Durability of Induction-Hardened Sintered Powder Metal Rollers and Gears with Various Hardened Depths

Effect of Shot Peening on Pitting Strength of Case-Hardened Steel Roller

To elucidate the effect of hardened depth on the fatigue strength of carbonitrided gears, gears with three kinds of hardened depths were fatigue-tested using a power circulating gear testing machine. In the case of gears with the shallowest and intermediate hardened depths, the failure mode was spalling. In the case of the gear with the greatest hardened depth, the failure modes were spalling and tooth breakage due to bending at the tooth fillet. The surface durability was higher with greater hardened depth. The bending strength of the gear with the greatest hardened depth was lower than that of the gear with intermediate hardened depth under the same loading condition. Therefore, when carbonitrided gears are designed, it is important to determine the optimum hardened depth of those gears. The change in dynamic performance of every gear was slight during the fatigue processes, since the change of tooth profile of every gear was slight.

Effect of Hardened Depth on Fatigue Strength of Carbonitrided Gears

This paper discusses failure diagnosis in gear sets using a wavelet transform (W). WT is a method used in time-frequency analysis. The health monitoring by the vibration acceleration of the gear box was carried out using a power circulating gear testing machine. A failed tooth could be found by changing the continuous WT intensity and the amplitude change of the discrete WT in the vibration acceleration. Since discrete WT can provide a signal with the component of tooth mesh frequency, discrete WT was superior to continuous WT. In this case of failure at the dedendum surface of a driven gear, the amplitude of the vibration acceleration with a component of tooth mesh frequency became larger after failed tooth meshing. Therefore, not only the vibration of the gear sets but also the condition of tooth meshing would have to be taken into consideration to diagnose the failed teeth.

Failure diagnosis on the tooth surface of gears by continuous and discrete wavelet transforms

In order to obtain fundamental data on the surface durability and surface failure mode of induction-hardened sintered powder metal rollers, rollers made of pre-alloyed powder with diameters 30 and 60 mm were fatigue-tested with case-hardened melted steel rollers under a sliding-rolling contact condition. The experimental results were discussed by the amplitude of the ratio of shear stress to Vickers hardness. The surface failure mode in this experiment was spalling due to subsurface cracking. The depth of the spalling crack agreed well with the depth of the peak amplitude of the ratio of orthogonal shear stress to Vickers hardness. The surface durability tended to increase as the relative radius of curvature decreased. There was an optimum hardened depth for the surface durability. The pores played an important role in the occurrence of cracks.

Yuji Ohue

Papers

Surface Failure and Durability of Induction-Hardened Sintered Powder Metal Rollers and Gears with Various Hardened Depths

Effect of Shot Peening on Pitting Strength of Case-Hardened Steel Roller

Effect of Hardened Depth on Fatigue Strength of Carbonitrided Gears

Failure diagnosis on the tooth surface of gears by continuous and discrete wavelet transforms

A Study on Surface Durability of Induction-Hardened Sintered Powder Metal Rollers (Influences of Hardened Depth and Relative Radius of Curvature)