Working gemstones
US5179931A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 1991 |
| Grant date | Jan 19, 1993 |
| Priority date | — |
| Expiry date | May 3, 2011 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB24B9/162
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
In order to brute a gemstone, the gemstone 6 is rotated about an axis and is ground with a small bruting crown 1 rotating about a parallel axis. In the peripheral working face of the bruting crown 1 are set grinding diamonds or stones 4 each of which subtends an angle .alpha. of at least about 10.degree. at the axis of the bruting crown 1. During working, reciprocatory axial motion is used between the bruting crown 1 and the gemstone 6. In order to set the end position of the bruting crown feed, the image 6' of the gemstone 6 and the image 1' of the bruting crown 1 are projected onto a screen 16. The screen 16 has indicia AB, BC, GH, IC representing the polished stone so that this polished stone can be fitted within the stone image 6'. The magnification of the optical system is changed and the stone is centered so that indicia in the form of bruted girdle diameter lines AB, GH represent the eventual bruted gridle diameter. The bruting crown 1 is then fed until the image of its profile is just inside the upper bruted girdle diameter line AD, and this position is set as the end position of the bruting crown feed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.