No. 9,309,925 | High Speed Machining Center
A micro-machine powered by an electric motor and/or a gas turbine drive and capable of rotation speeds to 1,500,000 rpm is disclosed. The micro-machine may include a rotating spindle which is constructed, balanced and arranged to provide a tool holder function and may incorporate a portion of the drive system. The other portion of the drive system is incorporated in a machine housing. The housing locates and supports at least one foil thrust bearing and at least one foil journal bearing to support the spindle. The housing and the bearings may be split into at least two parts and reassembled and the housing incorporates a gas reservoir and gas distribution channels for forced gas cooling of the bearings. In one embodiment of a foil journal bearing, a plurality of overlapping top foil segments supported by individual bump foil segments consisting of generally uniformly-spaced ridges and flats are secured within a housing. The bearing may be split and the bump foil stiffness may be adjusted by modifying the geometry, number and/or arrangement of the bump foils. In one embodiment of a foil thrust bearing a plurality of top foil segments are supported by coextensive individual bump foil segments including ridges and flats and secured on a thrust plate. The bearing may be split. The bump foil may be divided into a series of tabs separated by slits, each of the tabs having a number of ridges separated by flats. The ridges and flats on adjacent tabs may be arranged to reduce bearing heating. Provision may be made for cooling of the bearing by forced radial gas inflow.
- April 12, 2016