The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 04, 2000
Filed:
Sep. 30, 1997
Takayuki Yabe, Gunma, JP;
Nobuhide Kurachi, Gunma, JP;
NSK Ltd., Tokyo, JP;
Abstract
A ball screw includes a screw shaft 2 having an external ball-screw thread 2a, at least one ball nut 3 having an internal ball-screw thread which is opposite to the external ball-screw thread 2a of the screw shaft 2, a spiral raceway formed by combination of the internal ball-screw thread of the ball nut 3 and the external ball-screw thread 2a of the screw shaft 2, a plurality of balls which are circulated through the spiral raceway, and ball return paths 5, 6, and 7 for the plurality of balls. The ball screw also includes three or more circulation circuits X, Y, Z made by the spiral raceway and the ball return paths 5, 6, and 7 formed in the ball nut 3. Of the three or more three circulation circuits X, Y, Z, at least two circulation circuits are arranged so as to be in phase with each other in the circumferential direction of the ball screw 3, and the remaining circulation circuit is positioned so as to be 180 degree out of phase with the two circulation circuits in the circumferential direction. Accordingly it is possible to provide a compact ball screw having heavy load carrying capacity without increasing the size of the ball screw by averaging dispersions in the distribution of loads on the ball screw, and by reducing stress concentrated on the balls placed in a specific position.