| 摘要 |
PURPOSE:To enhance the accuracy of the degree of straightness and the degree of parallelism, in moving a central carriage left and right in a Y-axis direction, by preventing a main carriage from inclining left and right. CONSTITUTION:Dry air is supplied to air pads 41, 43, 45, 47 from an air supply device to form an air film not only between the air pad 41 and the upper surface of a slide guide surface 5 but also between the air pad 47 and the under surface of a slide guide part 7. As a result, for example, a central carriage 19 moves to the left side of the upper beam 9U of a main carriage 9 and, if the main carriage 9 itself is ready to incline to a left downward direction, the air pad 47 in the right side prevents the above-mentioned inclination to keep accuracy. For example, if the central carriage 19 moves to the right side of the main carriage 9 and the main carriage 9 itself is ready to incline to a right downward direction, the air pad 43 of the right side prevents the above- mentioned inclination to keep measuring accuracy.
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