07-07-2016 дата публикации
Номер: US20160194236A1
Принадлежит:
A process for manufacturing an optical element by hot-forming a glass sheet (), comprising the steps of: 12. A process for manufacturing an optical element by hot-forming a glass sheet () , comprising the steps of:{'b': 4', '5', '2', '9', '7', '6, 'setting a mold () provided with a surface () reproducing the shape to be given to the glass sheet () into a cavity () of a base element () of a muffle ();'}{'b': 2', '4', '14', '15', '7', '9, 'positioning the glass sheet () on the mold () with a peripheral edge superimposed to a closure area (, ) of the base element () surrounding said cavity ();'}{'b': 8', '6', '7', '17', '8', '2', '14', '15', '7, 'closing a cover () of said muffle () onto the base element (), so that a closure area () of the cover () maintains the peripheral edge of the glass sheet () in contact with the closure area (, ) of the base element ();'}running a thermal cycle including the step of warming up to a maximum temperature greater than the glass transition temperature of the glass and a step of controlled cooling; and{'b': 7', '8', '2', '4, 'at or after reaching the maximum temperature, generating a pressure difference between the base element () and the cover () so as to press the glass sheet () onto the mold ().'}2. A process as claimed in claim 1 , characterized in that said maximum temperature is greater than the glass transition temperature of the glass by 2-12% claim 1 , and preferably by 3-4%.3. A process as claimed in claim 1 , characterized in that said thermal cycle includes the step of maintaining the maximum temperature for at least 2 hours.4. A process as claimed in claim 1 , characterized in that said controlled cooling step includes the step of cooling with a gradient of less than 5° C./h at least until the glass annealing temperature is reached.5141571781622. A process as claimed in claim 1 , characterized in that at least one of said closure area ( claim 1 , ) of the base element () and a corresponding closure area () of the cover ...
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