| US 7,530,282 B2 | ||
| Ball screw apparatus | ||
| Shingo Saitou, Kanagawa (Japan); and Koji Hashimoto, Kanagawa (Japan) | ||
| Assigned to NSK Ltd., Tokyo (Japan) | ||
| Filed on Oct. 25, 2005, as Appl. No. 11/257,101. | ||
| Prior Publication US 2007/0137344 A1, Jun. 21, 2007 | ||
| Int. Cl. F16H 1/18 (2006.01) | ||
| U.S. Cl. 74—424.75 [74/424.85] | 1 Claim |
| 1. A ball screw apparatus of a screw shaft circulating-type comprising:
a nut having a first groove on an inner peripheral surface thereof;
a screw shaft having a second groove on an outer peripheral surface thereof; and
a plurality of rolling elements provided between the first and second grooves;
wherein a circulating groove, which connects both ends of the second groove so as to infinitely circulate the rolling element
is provided on the screw shaft,
a relief portion is provided on an area at which the circulating groove connects with the second groove, and
a groove width of the relief portion is smaller than a width of the circulating groove and is larger than a width of the second
groove.
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