Thermal Behavior of an Improved Face-Grinding Spindle: Water-Lubricated Hydrostatic Thrust Bearing Decreases Temperature Rise and Increases Axial Stiffness

Axial thermal deformation and axial stiffness are main technical indicators to affect manufacturing accuracy of face-grinding spindle. However, the face-grinding spindle supported by rolling bearings lubricated with grease has a relative disadvantage in respect of temperature rise, axial stiffness and rotational accuracy. To overcome this issue, this study proposes a novel face-grinding spindle supported by a combined bearings, which include a water-lubricated hydrostatic thrust bearing and two rolling bearings with oil-air lubrication system. The thermal model for the proposed face-grinding spindle is established and the spindle thermal behavior is analyzed systematically. An experiment prototype of the face-grinding spindle is developed, and temperature rise of the spindle is detected to verify the thermal model. The result shows that the temperature rise of the proposed spindle can be decreased by the using of the water-lubricated hydrostatic thrust bearing. A comparative study between the two types of spindles shows that the proposed face-grinding spindle with the combined support has technical advantage of low temperature rise, large axial stiffness and low rotation accuracy, etc.