高圧静圧軸受の混合潤滑特性

部材の弾性変形が最適設計条件に及ぼす影響

抄録

At the maximum supply pressure of 55 MPa (the maximum load of 15 kN), circular hydrostatic thrust bearings are investigated in mixed to fluid film lubrication experimentally and theoretically. The effect of elastic deformation on the tribological characteristics is examined and the optimal criterion for high-pressure or tap-water hydraulic pumps and motors is discussed. The bearing diameter was 20 mm and the recess radius ratio was 0.5. The bearings tested were made of carbon steel, bearing steel and plastics (polyetheretherketone; PEEK), whose surface roughness was finished from 0.05 to 3.6μmRa. Hydraulic fluid with ISO VG 32 was used as the test liquid. Frictional torque and leakage flow rate were measured and power loss was assessed in a wide range of operating conditions. As regards the specimens with rough surface, the power loss minimized when the hydrostatic balance ratio, defined by the ratio of the load to the maximum hydrostatic load-carrying capacity, was set close to unity. By contrast, for the specimens with smooth surface, the ratio exceeded unity as the supply pressure increased. The elastic effect became notable when the supply pressure and the load were established higher and/or the specimens were made of plastics. The experimental data was in good agreement with the theoretical results considering elastic analysis.