| 摘要 |
An improved ball nut (10) having adjustable preloading comprises a pair of ball nut halves (12a, 12b) both in threaded engagement with a ball screw (14). Only one of the nut halves is secured to a movable machine member, the other nut half being movable to the relative fixed nut half. Separating the two nut halves is a pair of concentric sleeves, (20a, 20b) which are each fabricated from a piezomagnetic material such as nickel or nickel alloy. The sleeves are each keyed to the nut halves to prevent one nut half from rotating independently of the other. Between the sleeves is a magnetic coil (22) which, when energized, causes the sleeves to expand. By varying the coil excitation, the sleeve length, and hence, the force exerted on the ball nut halves by the sleeves can be varied accordingly to vary bal nut preloading. |
