Back to results
US 4,231,778 AGranted
Method of strengthening glass articles
AssigneeOwens-Illinois, Inc.
InventorsPaul W. L. Graham, Thomas W. Moore, Jr.
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeOwens-Illinois, Inc.
InventorsPaul W. L. Graham, Thomas W. Moore, Jr.
Estimating the term…
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.
The method of strengthening newly-formed glass articles having surface defects in their exterior surfaces comprising the steps of allowing the said newly-formed glass articles to partially cool immediately following their formation, immediately rapidly heating the defect-containing newly-formed exterior surfaces of said articles to an elevated temperature ranging from about 1000.degree. to 1250.degree. F. for a period of time ranging from about 1 second to about 6 minutes, depending upon selection of the heat source, said time period being less than that which would cause visible softening or fusing of the said exterior surfaces, and then annealing said glass articles to remove stresses therefrom.
The method of strengthening newlyformed soda-lime containers having surface defects in their exterior surfaces comprising the steps of allowing the said newly-formed glass containers to cool to a temperature ranging from about 800.degree. to 1100.degree. F. immediately following their formation, immediately rapidly heating the defect-bearing, newly-formed exterior surfaces of said containers to a temperature ranging from about 1000.degree. to 1250.degree. F. for a period of time of about 1 to 4 seconds, said time period being less than that which would cause visible softening or fusing of said glass surfaces, and then annealing said glass containers to remove stresses therefrom, at least some of said defects remaining visible in said defect-bearing exterior surfaces, thereby significantly strengthening said glass containers by about 10 to 50 percent greater than their original strength as indicated by internal pressure strength tests.
The method of strengthening newly-formed soda-lime glass containers having surface defects in their exterior surfaces comprising the steps of allowing the said newly-formed glass containers to cool to a temperature ranging from about 800.degree. to 1100.degree. F. immediately following their formation, immediately rapidly heating the defect-bearing newly-formed exterior surfaces of said containers to a temperature ranging from about 1000.degree. to 1250.degree. F. for a period of time of about 1 to 6 minutes in an oven, said time period being less than that which would cause visible softening or melting of said glass surfaces, and then annealing said glass containers to remove stresses therefrom, at least some defects remaining visible in said defect-bearing exterior surfaces, thereby significantly strengthening said glass containers by about 10 to 50 percent greater than their original strength as indicated by internal pressure strength tests.
Dependencies are inferred from the claim text.