DRILL SPINDLE UNIT
A drill spindle unit includes a housing, and a rotatable and longitudinally displaceable drill spindle provided with axial keyways for cooperation with internal projections of a drill spindle surrounding rotation drive sleeve, and a screw thread for cooperation with an internal thread of a drill spindle surrounding feed drive sleeve. Bearings for radial as well as axial support of the drill spindle relative to the housing are provided. The radial support bearings are arranged to transfer radial forces only, and a thrust bearing is arranged to transfer axial forces between the housing and the drill spindle. The thrust bearing is associated with an axial load sensing device by which signals are generated in response to the axial load applied on the drill spindle.
1 - 4 . (canceled)
5 . A drill spindle unit comprising:
a housing;
a drill spindle which is rotatable and longitudinally displaceable relative to the housing and connected to a drive motor, wherein the drill spindle is provided with axially extending keyways for cooperation with internal projections of a drill spindle surrounding rotation drive sleeve, and a screw thread for cooperation with an internal thread of a drill spindle surrounding feed drive sleeve; and
bearings for radial and axial support of the drill spindle relative to the housing;
wherein said bearings comprise:
at least one radial bearing for transferring radial forces only between the housing and the feed drive sleeve; and
a single thrust bearing for transferring axial forces only between the housing and the feed drive sleeve; and
wherein an axial force sensing device is associated with said thrust bearing and is arranged to deliver axial force responsive electric signals.
6 . The drill spindle unit according to claim 5 , wherein said radial bearings, said thrust bearing, and said axial force sensing device are arranged between the feed drive sleeve and the housing.
7 . The drill unit according to claim 5 , wherein said radial bearings comprise needle bearings.
8 . The drill unit according to claim 6 , wherein said radial bearings comprise needle bearings.
9 . The drill unit according to claim 5 , wherein the drive motor comprises a pneumatic motor.
10 . The drill unit according to claim 6 , wherein the drive motor comprises a pneumatic motor.
11 . The drill unit according to claim 7 , wherein the drive motor comprises a pneumatic motor.