主权项 |
1. A ball screw comprising a screw shaft, a nut, and a plurality balls, wherein,
the screw shaft passes through the nut, a rolling path along which the balls roll is formed by a helical groove formed on an outer peripheral surface of the screw shaft and a helical groove formed on an inner peripheral surface of the nut, the balls are disposed in the rolling path, and a seal is attached to at least one end of ends of the nut in a moving direction of the nut, the seal surrounds an outer periphery of the screw shaft and comprises: a seal mountain inside the seal entering the helical groove of the screw shaft; a tubular portion exposed axially outside the nut; a grease reservoir portion provided on an inner peripheral surface of the tubular portion so as to form a space with respect to the screw shaft; a discharge outlet communicating with the grease reservoir portion and open to an outer peripheral surface of the tubular portion; and a slit communicating with the discharge outlet, extending axially in the tubular portion of the seal, and inclined with respect to a line in a diameter direction of the screw shaft in a counterclockwise direction as viewed from an outer end face of the tubular portion when the screw shaft has right-hand threads and in a clockwise direction as viewed from the outer end face of the tubular portion when the screw shaft has left-hand threads. |