Claims
- 1. A method of thermally treating a glass sheet in a bed of gas-fluidised particulate material, comprising maintaining said gas-fluidised bed at a glass-treatment temperature, heating a glass sheet to a temperature above its strain point, commencing extraction of gas from a localised upper region of the bed prior to the lowering of the hot glass sheet into the bed, regulating the rate of gas extraction to produce gradually an unfluidised static packed condition of the particulate material in the upper region of the bed, and lowering the glass sheet into the bed at a time after commencement of gas extraction which is such that the lower edge of the hot glass sheet passes through said upper region of the bed prior to full attainment of the static packed condition of the particulate material in said upper region.
- 2. A method of thermally toughening a glass sheet in a bed of gas-fluidised particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, comprising maintaining said gas-fluidised bed at glass-quenching temperature, heating a glass sheet to a temperature above its strain point, commencing extraction of gas from a localised upper region of the bed prior to the lowering of the hot glass sheet into the bed, regulating the rate of gas extraction to produce gradually an unfluidised static packed condition of the particulate material in the upper region of the bed, and lowering the glass sheet into the bed at a time after commencement of gas extraction which is such that the lower edge of the hot glass sheet passes through said upper region of the bed prior to full attainment of the static packed condition of the particulate material in said upper region.
- 3. A method of thermally toughening a glass sheet in a bed of gas-fluidised particulate material, comprising maintaining said gas-fluidised bed at glass-quenching temperature, heating a glass sheet to a temperature above its strain point preparatory to lowering of the sheet into the bed, commencing extraction of gas from either side of the path of the glass sheet in a region of the upper part of the bed prior to the lowering of the hot glass sheet into the bed, regulating the rate of gas extraction to produce gradually an unfluidised static packed condition of the particulate material in said region of the upper part of the bed, and lowering the hot glass sheet into the bed at a time after commencement of gas extraction which is such that the lower edge of the hot glass sheet passes through said region of the upper part of the bed prior to full attainment of the static packed condition of the particulate material in said region.
- 4. A method according to claim 1, claim 2 or claim 3, comprising timing the lowering of the glass sheet into the bed so that the whole of the glass sheet passes through said upper region of the bed prior to full attainment of the static packed condition of the particulate material in said upper region.
- 5. A method of operating a bed of gas-fluidised particulate material in which a hot glass article is to be treated, comprising commencing extraction of gas from a localised region of the bed prior to entry of the hot glass article into that region of the bed, regulating the rate of gas extraction to defluidise particulate material in that region gradually thereby producing gradually an unfluidised static packed condition of the particulate material in said localised region of the bed, and entering the hot glass article into the bed at a time after said commencement of gas extraction which is such that a leading part of the article passes through said localised region prior to full attainment of the static packed condition of the particulate material in said localised region.
- 6. A method of thermally toughening a glass article in a bed of gas-fluidised particulate material, comprising maintaining said gas-fluidised bed at a glass-treatment temperature, heating the glass article to a temperature above its strain point, commencing extraction of gas from a localised upper region of the bed prior to the lowering of the hot glass article into the bed, regulating the rate of gas extraction to defluidise particulate material in that region gradually thereby producing gradually an unfluidised static packed condition of the particulate material in said upper region of the bed, and lowering the glass article into the bed at a time after commencement of gas extraction which is such that a lower part of the hot glass article passes through said upper region of the bed prior to full attainment of the static packed condition of the particulate material in said upper region.
- 7. A method according to claim 6, comprising timing the lowering of the glass article into the bed so that the whole of the glass article passes through said upper region of the bed prior to full attainment of the static packed condition of the particulate material in said upper region.
Priority Claims (1)
Number |
Date |
Country |
Kind |
40564/77 |
Sep 1977 |
GBX |
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Parent Case Info
This is a continuation of application Ser. No. 944,612 filed Sept. 21, 1978, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3423198 |
McMaster et al. |
Jan 1969 |
|
4066430 |
Franz |
Jan 1978 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
944612 |
Sep 1978 |
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