| 摘要 |
PURPOSE:To prevent a feed thread and a nut from being damaged by overdriving, by detecting a separating distance of magnetic coupling between the nut, screwed to the feed thread, and an attractive plate on a carriage sliding along a guide. CONSTITUTION:A nut 5 is screwed to a feed thread 3, and the nut 5 provides in its attractive surface to an attractive plate 4 a microswitch 11 with a magnet 6. This microswitch 11 is connected with a power supply circuit for a driving source of the feed thread 3 so that its driving may be stopped when the attractive plate 4 separates from the nut 5. Consequently, if a carriage 1 stops due to sliding resistance or the like, the nut 5, only moving alone, separates from the attractive plate 4, and the driving source is stopped by opening the microswitch 11. As a result, a mover prevents a thread ridge of the feed thread and the nut from being damaged.
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