Ball screw
AssigneeNtn Corporation
InventorKeisuke Kazuno
Life of this patent
Estimating the term…
Abstract
A ball screw, which improves its durability under circumstances where a radial load and a moment load are applied to it, has a screw shaft (2) formed with a helical screw groove (2a) on its outer circumferential surface. A nut (3) is adapted to mate with the screw shaft (2). The nut (3) is formed with a helical screw groove (3a) on its inner circumferential surface. The nut helical screw groove (3a) corresponds to the screw shaft screw groove (2a). A number of balls (4) are rollably contained within a ball rolling passage formed by the oppositely arranged screw grooves (2a, 3a). Bridge members (5), each formed with a connecting groove (5a) on its inner circumferential surface, connect the screw grooves (3a) of the nut (3). A contact angle (α) between each ball (4) and one or both the screw grooves (2a, 3a) is set within a range of about 20˜40°.
Claims4
A ball screw comprising:
- a screw shaft formed with a helical screw groove on its outer circumferential surface;
- a nut adapted to mate with the screw shaft, said nut formed with a helical screw groove on its inner circumferential surface, said nut helical screw groove corresponding to the screw shaft screw groove;
- a number of balls rollably contained within a ball rolling passage formed by oppositely arranged screw grooves;
- and
- bridge members, each formed with a connecting groove on its inner circumferential surface, for connecting the nut screw grooves;
- and
- a contact angle between the ball and the screw groove is set within a range of about 20˜40°.
Dependencies are inferred from the claim text.