Method of strengthening glass articles
US4231778A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 1979 |
| Grant date | Nov 4, 1980 |
| Priority date | — |
| Expiry date | May 18, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03B29/06
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
This invention relates to a process for strengthening glass articles immediately after their formation and prior to annealing to remove stresses, and more specifically to increasing the strength of glass containers in terms of internal pressure retention as well as in thermal shock and impact resistance. The process involves allowing the newly-formed glass containers to cool down to a limited extent immediately subsequent to their formation, subjecting the defect-bearing exterior surfaces of the glass containers, which contain surface checks or cracks, to an elevated temperature for a brief period of time to physically alter the crack geometry of the defects and partially heal the same, and then annealing the glass containers to remove stresses therefrom. The glass containers then exhibit a strengthening of at least 10 to 20 percent, and in some cases as much as a 50 percent increase over their average untreated strength based on internal pressure strength tests which are indicative of overall strengthening of glass surfaces.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.