TEST BENCH FOR CHARACTERIZATION OF HYDROSTATIC BEARINGS

Abstract

In this research work, an experimental test bench has been designed and constructed to analyze the behavior of lubricated bearings, and validate an own developed theoretical model for bearings calculations. The test bench is composed of a high precision shaft (lapped and guided by ultraprecision rolling bearings) and in the middle of the two rest points a lubricated bearing test is located. This lubricated bearing is fully monitored, with positioning probes (micrometric resolution), pressure gauges and temperature sensors. The bearing has four pads, and each pad has been monitored. The oil is pumped at constant pressure and controlled temperature, this way different operating conditions can be tested. The flow-rate of inlet fluid is measured by a flow meter. The load is applied in the radial direction, by a hydraulic actuator directly to the bearing, with a system of ropes that ensures a controlled direction of the pulling force and stability in the experiment. Axial movement is limited by rolling elements, this way the movement of the bearing is limited to the vertical plane, measuring 2D displacements in positioning probes. The bearing is manufactured with sliding polymer material, by injection process. This solution allows quick changes in the shape of the bearing’s recesses, from designs closer to hydrostatic lubrication, or hydrodynamic ones. The experimental results have been used to validate a model of bearings lubrication from internal development . This model is based on Reynolds equation solution for hydrodynamic lubrication on the bearing lands, and hydrostatic lubrication for recesses, following the current bibliography. Therefore, a test bench for hydrostatic bearing has been developed in order to vatidate a theoretical model for bearings calculations. Keywords: Hydrostatic bearings, hydrodynamic lubrication, test bench, machine tool, spindle.