Development and Modeling of Water Driven Stage

The water driven stage that is developed for ultra-precision machine tools is presented. The stage is designed for the diamond turning of small precise parts, such as various small lenses or mirrors. The moving table of the water driven stage is supported by water hydrostatic bearings. The stage is driven by the water hydraulic piston-cylinder mechanism that is designed inside the table. A feature of the stage is that the driving force by the piston-cylinder mechanism acts on the center of gravity of the moving table, minimizing undesirable pitching and yawing motions. In order to investigate the characteristics of the stage, a mathematical model of the water driven stage is derived. Performances of the water driven stage are examined through experiments and calculations. The present study verifies that the feed motion needed for the diamond turning operations can be obtained by supplying few flow rate of water, several tens milliliters per minutes. Stiffness of the water hydrostatic bearing is also experimentally investigated. The result shows that stiffness is approximately 330 N/μm if the supply pressure was 0.5 MPa.