| 摘要 |
An ultra-precision machine tool capable of accurately detecting a machining start position, in which movable axes are supported by fluid bearings. A workpiece is mounted on a rotary table of a B axis, and the rotary table is mounted on an X axis that is a linear motion axis. A tool is mounted on a Y axis. The Y axis is mounted on a Z axis. The X axis is moved reciprocally each time the Z axis is moved a predetermined amount, a machining surface of the workpiece is scanned, and it is determined whether or not position deviation of the X, Y and B axes reaches or exceeds a reference value. The Y axis is driven and the tool is moved toward the workpiece a predetermined amount, and the above-described scan is performed. When the position deviation of the X, Y and B axes reaches or exceeds the reference value it is determined that contact between the tool and the workpiece has occurred, and this contact point is stored as the machining start position, the Y axis is skipped, and the tool is moved a predetermined amount in a direction away from the workpiece, thus enabling a point of maximum protrusion from the machining surface of the workpiece to be simply detected as the machining start point.
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