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1. (WO1999006740) BALL SCREW DEVICE

Pub. No.:    WO/1999/006740    International Application No.:    PCT/JP1998/003390
Publication Date: Fri Feb 12 00:59:59 CET 1999 International Filing Date: Fri Jul 31 01:59:59 CEST 1998
IPC: F16C 33/38
F16H 25/22
Applicants: THK CO., LTD.

EBINA, Shigeru


Inventors: EBINA, Shigeru


A ball screw device provided with a screw shaft having on the outer peripheral surface thereof a spiral ball rolling groove, a nut assembly having a load region composed of a spiral load rolling groove facing the ball rolling groove of the screw shaft and a non-load region connecting for communication start and terminal ends of the load region with each other to define an endless track for balls, and a ball connecting body formed of a multiplicity of balls rolling on the endless track of the nut assembly and a connecting body for rotatably holding the balls in an aligned state, wherein a guide groove is formed in the endless track of balls for guiding the connecting body of the ball connecting body to the non-load region so that the respective balls move the connecting body in the load region and the connecting body guides and moves the respective balls in the non-load region of the endless track, and leading portions are formed at least both end portions of the non-load region near the load region for guiding the connecting body along a direction in which the balls moving in the load region advance. Transfer of the balls between the load region and the non-load region in the endless track is made smoothly to achieve smooth circulation of the balls.