Patent US6296949B1 successfully refreshed from Google Patents.
US3847580A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of tempering glass
Assignee: PPG Industries Inc
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Filing: 1973-03-21
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Granted: 1974-11-12
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Expires: 1993-03-21
Abstract
Abstract Incidents of breakage in glass sheets during tempering are reduced by conducting the quench operation in steps of which the first is the most severe and the others are accordingly less severe, but still such as not to permit untempering of the surfaces of the glass.
Inventors
- 👤 G Misson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:09
CPC Classifications
C; C03; C03B; C03B27/00; C03B27/04; C03B27/0404; C03B27/044; C03B27/048
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
248 words
An improved method of tempering soda-lime glass in sheet form which comprises, heating said sheet of glass substantially uniformly throughout its thickness to a temperature approaching its softening temperature, supporting said sheet of glass on a modular gas support bed affording a relatively high heat transfer coefficient, applying to said sheet of glass, as it moves edgewise in a first stage of quenching, supporting flows of cooling gas on one side of said sheet of glass and opposing flows on the opposite side that are at a first and relatively high volumetric flow rate of cooling gas per unit of surface-support area until the center plane temperature of said sheet of glass is reduced to below the strain point of the glass and the surface temperature of said sheet of glass is reduced to below the center plane temperature, and then in a second stage of quenching, applying to said sheet of glass, as it continues to move edgewise, supporting and opposing flows of cooling gas that are at a second and relatively lower volumetric flow rate of cooling gas per unit of surface-support area until the surface and center plane temperatures of said sheet of glass are further reduced to substantially below the strain point of the glass, whereby tempering of the glass is effected with less total power consumption than is requireD when there is used a single flow rate per unit of surface-support area adequate to obtain the desired degree of temper in said glass.
Claim 2
Dependent Claim
248 words
An improved method of tempering soda-lime glass in sheet form which comprises, heating said sheet of glass substantially uniformly throughout its thickness to a temperature approaching its softening temperature, supporting said sheet of glass on a modular gas support bed affording a relatively high heat transfer coefficient, applying to said sheet of glass, as it moves edgewise in a first stage of quenching, supporting flows of cooling gas on one side of said sheet of glass and opposing flows on the opposite side that are at a first and relatively high volumetric flow rate of cooling gas per unit of surface-support area until the center plane temperature of said sheet of glass is reduced to below the strain point of the glass and the surface temperature of said sheet of glass is reduced to below the center plane temperature, and then in a second stage of quenching, applying to said sheet of glass, as it continues to move edgewise, supporting and opposing flows of cooling gas that are at a second and relatively lower volumetric flow rate of cooling gas per unit of surface-support area until the surface and center plane temperatures of said sheet of glass are further reduced to substantially below the strain point of the glass, whereby tempering of the glass is effected with less total power consumption than is requireD when there is used a single flow rate per unit of surface-support area adequate to obtain the desired degree of temper in said glass.
Claim 3
Dependent Claim
86 words
A method as defined in claim 1, characterized in that said first volumetric flow rate and the temperature of the cooling gas supplied thereat are so chosen that the temperature of the center plane in said glass is decreased to about 490* C. or less within about 3 seconds, and in that said second volumetric flow rate and the temperature of the cooling gas supplied thereat are so chosen that the surface temperature of the glass does not thereafter increase by more than about 45* C.
Claim 4
Dependent Claim
25 words
A method as defined in claim 1 characterized in that glass is moved through the first and second stage of quenching at a uniform rate.
Claim 5
Dependent Claim
72 words
A method as defined in claim 1 characterized in that glass of about 3 millimeters in thickness enters the first stage of quenching at a temperature about 670*C., is cooled therein to a center plane temperature about 480*C. in a time period of about 3 seconds and is further cooled in said second stage to a center plane temperature about 315*C. in a further time period of about 4 seconds in duration.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |