Ball screws and ball screw sealing members

Abstract

The present invention provides a ball screw that prevents lubricant leakage during normal use and allows for easy discharge of old lubricant when supplying new lubricant, thereby preventing seal damage and maintaining good lubrication. [Solution] The ball screw 10 comprises a screw shaft 20 having a screw groove 21 formed on its outer circumference, a nut 30 having a screw groove 31 formed on its inner circumference, a plurality of balls 22 that roll along a load trajectory formed by the screw groove 21 of the screw shaft 20 and the screw groove 31 of the nut 30, and a sealing member 50 attached to the axial end of the nut 30 to seal the gap 12 between the screw shaft 20 and the nut 30. The sealing member 50 has a lubricant discharge portion 13, which is closed when the pressure inside the nut 30 is equal to the pressure outside the ball screw 10, and opens to penetrate the screw shaft 20 in the axial direction when the pressure inside the nut 30 increases.

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