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US 4,669,359 AGranted
Positioning system
AssigneeCitizen Watch Co., Ltd.
InventorKazuo Shiba
Life of this patent
Estimating the term…
Abstract
A system for positioning a movable body for a processing machine. A lead screw is rotatably and axially shiftably supported and engaged with the movable body. The lead screw is rotated by a motor to move the movable body. A hydrostatic thrust bearing is provided for preventing axial movement of the lead screw. The lead screw is finely moved in the axial direction by controlling the pressure difference of oil supplied to the thrust bearing to position the movable body.
Claims7
A system for positioning a movable body slidably mounted on a bed, comprising:
- a lead screw rotatably and axially shiftably supported in said bed by bearings and engaged with said movable body through a nut so as to move it;
- a flange formed on the lead screw at an end portion thereof;
- a hydrostatic thrust bearing comprising a pair of opposed pockets formed in one of said bearings at both sides of said flange so as to prevent the axial movement of the lead screw;
- a motor operatively connected to said lead screw through a coupling so as to allow axial movement of said lead screw to rotate it to move said movable body;
- means including sensing means for sensing the position of the movable body and for producing a signal dependent on the position;
- a hydraulic circuit for applying hydrostatic pressure to the opposed pockets;
- and
- servo valve means provided in the hydraulic circuit and responsive to the signal for regulating the hydrostatic pressure applied to the pockets to axially move the lead screw, causing an axial movement of the movable body.
5 more elements
Dependencies are inferred from the claim text.