Patent ID: 6776063
Filing Date: 2004-08-17
Classification: F16C,F16H,Y10T

Abstract:
A ball screw comprising:a screw shaft (11) including a first spiral groove (12) formed on an outer peripheral surface of the screw shaft; a nut (13) disposed on the side of the outer periphery of said screw shaft and having a second spiral groove (14) formed on an inner peripheral surface of said nut in such a manner that said second spiral groove is opposed to said first spiral groove; a plurality of balls (15) rollably held between said second spiral groove and said first spiral groove; and, a ball circulation tube (20) attached to said nut for forming a circulation passage of said balls, wherein said ball circulation tube (20) has such a cross-sectional shape that a movable amount (T+&agr;) of said balls in a first direction (X) intersecting at right angles to an axis of said ball circulation tube is larger than a movable amount (T) of said balls in a second direction intersecting at right angles to said axis of said ball circulation tube and also at right angles to said first direction, and wherein said ball circulation tube is fixed to said nut in such a manner that an outer surface (20a) of said ball circulation tube that extends in parallel with said first direction is confronted with the outer surface of said nut.