Screw and nut machine
US5022277A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 22, 1989 |
| Grant date | Jun 11, 1991 |
| Priority date | — |
| Expiry date | Aug 22, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/19786
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A ball screw has a plurality of planar tracks of bearing balls arranged around the inner surface of the nut of a screw and nut machine. The shape of each track is designed to fit around a planar cross-section of the screw threads and each of the plurality of tracks is oriented at different angles with respect to the other tracks. A carrier is placed between the nut and screw and maintains the bearing balls separated from one another. In addition, each of the plurality of tracks are spaced at a fraction of the pitch of the screw thread pitch. By making each track planar, the bearing balls circulate within each track independently of the other tracks. In addition, a technique to design the shape of the track for a given thread shape includes determining the tangential point of each ball along the thread. The tracks may be divided into groups having a forward drive and reverse drive bias and the track may be made larger than the bearing balls to reduce wear at the thread peak.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.