When the shaft current passes through the bearing under lubrication condition, the arc often occurs and the pitting can be observed on the surface of bearing. Consequently, the life of bearing is shortened. The pitting resulting from discharge is dependent upon the shaft voltage, the oil film thickness, and the insulation of lubricant. To simulate the pitting, the dynamic pitting tester is developed to investigate the effects of the kinematics parameters on the electrical pitting formation mechanism for the common material of bearing by changing the supply voltage current and the oil film thickness.
Result show that in the static condition, since the arc action causes the surface melting of two specimens, and the actions of coulomb force and electrostatic force cause the specimens to attract each other, the plateau can be observed on the surfaces of specimens. The plateau is like a bridge to connect two specimens. In this moment the plateau accumulates continuously and causes two specimens to produce the repulsive force. In the dynamic condition, the formation of pitting at the initial stage is quite similar to that in the static condition. Since the effect of sliding speed, the bridge is sheared and the friction force increases. Under the actions of joule heat and friction force, the surfaces of two specimens melt and scratch continuously.
When the dynamic pitting occurs, the pitting width of square specimen, the normal force and the friction force increases with increasing supply voltage, supply current, and oil film thickness. When the interface power is larger, the melting phenomenon is more obvious, and the pitting width becomes larger. Because the surface melting and the actions of Coulomb force and electrostatic force cause the material accumulates continuously, the normal force and the friction force increase with increasing the interface power. To investigate all effects of experimental parameters on the pitting width, the empirical formula for the pitting width is established in terms of supply voltage, supply current, and oil film thickness. This formula can be used to predict oil film thickness or the size of pitting width on the bearing surface for diagnosing the lubricant condition of bearing.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0731103-151105 |
| Date | 31 July 2003 |
| Creators | Lin, Shin-Min |
| Contributors | none, none, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0731103-151105 |
| Rights | unrestricted, Copyright information available at source archive |
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