| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw device provided with a position measurement instrument at a low cost and with good detecting accuracy, by providing it with a magnetic material on a screw shaft side so that a position is detected as a change in the magnetic energy of the magnetic material using a magnetic sensor provided on a nut side. SOLUTION: The ball screw device has a screw shaft having a spiral screw groove in the outer peripheral face, a nut having a screw groove corresponding to the screw groove of the screw shaft in the inner peripheral face, and the nut is moved in the axial direction of the screw shaft, and a number of balls for rolling in a circulation passage formed by both screw grooves of the screw shaft and the nut, thereby, the nut is reciprocated relative to the screw shaft in the axial direction. The screw shaft has a spiral protruded portion formed on the outer peripheral face between adjacent screw grooves, and the protruded portion has a spiral groove formed in the outer peripheral face. The linear magnetic material is embedded in the spiral groove with S-poles and N-poles alternately arranged thereon so that a change in the magnetic energy of the magnetic material is detected. COPYRIGHT: (C)2005,JPO&NCIPI
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