Thermally tempered glass and methods and apparatuses for thermal tempering of glass
First Claim
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1. Process for strengthening a sheet, the process comprising:
- cooling a sheet comprising a material, the sheet having first and second sheet surfaces, the material having a transition temperature, the sheet being at a temperature greater than the transition temperature at the start of the cooling, wherein the cooling is performed;
a. positioning the first sheet surface adjacent to a first heat sink surface with a first gap between the first sheet surface and the first heat sink surface such that thermal conduction from the first sheet surface to the first heat sink surface occurs, the first gap having a length across the first gap of g1 and an area of the first gap of Ag1,b. positioning the second sheet surface adjacent to a second heat sink surface with a second gap between the second sheet surface and the second heat sink surface such that thermal conduction from the second sheet surface to the second heat sink surface occurs, the second gap having a length across the second gap of g2 and an area of the second gap of Ag2,c. providing a first flow of a first gas to the first gap and providing a second flow of a second gas to the second gap, the first gas having a heat capacity Cp1 and a thermal conductivity k1, the second gas having a heat capacity Cp2 and a thermal conductivity k2, the flow provided at a mass flow rate {dot over (m)}1 of the first gas, wherein {dot over (m)}1 is greater than zero and less than (2k1Ag1)/(g1Cp1), to the first gap, and at a mass flow rate {dot over (m)}2 of the second gas, wherein {dot over (m)}2 is greater than zero and less than (2k2Ag2)/(g2Cp2), to the second gap, whereby the first and second flows contact the sheet, and the sheet is cooled, by conduction more than by convection,d. sufficiently to cool the sheet to a temperature below the transition temperature.
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Abstract
A strengthened glass sheet product as well as process and an apparatus for making the product. The process comprises cooling the glass sheet by non-contact thermal conduction for sufficiently long to fix a surface compression and central tension of the sheet. The process results in thermally strengthened glass sheets having improved breakage properties.
104 Citations
12 Claims
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1. Process for strengthening a sheet, the process comprising:
cooling a sheet comprising a material, the sheet having first and second sheet surfaces, the material having a transition temperature, the sheet being at a temperature greater than the transition temperature at the start of the cooling, wherein the cooling is performed; a. positioning the first sheet surface adjacent to a first heat sink surface with a first gap between the first sheet surface and the first heat sink surface such that thermal conduction from the first sheet surface to the first heat sink surface occurs, the first gap having a length across the first gap of g1 and an area of the first gap of Ag1, b. positioning the second sheet surface adjacent to a second heat sink surface with a second gap between the second sheet surface and the second heat sink surface such that thermal conduction from the second sheet surface to the second heat sink surface occurs, the second gap having a length across the second gap of g2 and an area of the second gap of Ag2, c. providing a first flow of a first gas to the first gap and providing a second flow of a second gas to the second gap, the first gas having a heat capacity Cp1 and a thermal conductivity k1, the second gas having a heat capacity Cp2 and a thermal conductivity k2, the flow provided at a mass flow rate {dot over (m)}1 of the first gas, wherein {dot over (m)}1 is greater than zero and less than (2k1Ag1)/(g1Cp1), to the first gap, and at a mass flow rate {dot over (m)}2 of the second gas, wherein {dot over (m)}2 is greater than zero and less than (2k2Ag2)/(g2Cp2), to the second gap, whereby the first and second flows contact the sheet, and the sheet is cooled, by conduction more than by convection, d. sufficiently to cool the sheet to a temperature below the transition temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Process for strengthening a sheet, the process comprising:
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a. supporting at least a portion of a sheet on a first surface thereof, at least in part, by a flow or a pressure of a gas delivered to a gap between the first surface and a first heat sink, wherein the sheet comprises a glass having a transition temperature and the sheet is at a temperature greater than the transition temperature of the glass; b. cooling the sheet, by thermal conduction more than by convection, from the first surface of the sheet through the gas to the first heat sink, to a temperature below the transition temperature.
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12. Process for strengthening a sheet, the process comprising:
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Heating a sheet comprising a material having first and second sheet surfaces, the material having a transition temperature, the heating performed sufficiently to bring the sheet above the transition temperature; positioning the first sheet surface adjacent to a first heat sink surface across a first gap, the first heat sink surface having first multiple apertures; positioning the second sheet surface adjacent to a second heat sink surface across a second gap, the second heat sink surface having second multiple apertures; delivering a gas into the first and second gaps through the first and second multiple apertures and cooling the sheet by conduction more than by convection, and to a temperature below the transition temperature.
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Specification