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AssigneeInternational Partners in Glass Research
InventorsDavid Braithwaite, Robert J. Douglas, Stanley P. Jones, James P. Poole, Harold Rawson
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An article of glassware, particularly a glass container, of increased strength is made by a process in which the parison is treated in a manner which will cause the glass in the outer surface layer of the formed glassware article to be in a state of compression. Preferably a glaze having a coefficient of thermal expansion lower than the coefficient of thermal expansion of the glass of the parison is applied to the outer surface of the parison. Advantageously, the glaze is applied to the parison by a flame spray method or by dipping the parison into a fluidized bed containing powdered glaze. As an alternative, the glaze applied to the outer surface of the parison may be capable of being at least partially crystallized, after the glassware article has been formed from the parison, to produce an outer surface of the glassware article having a lower coefficient of thermal expansion than the base glass of the glassware article. Alternatively to the application of a glaze, glass in the outer surface of the parison may be chemically changed so that the surface glass in the parison has a higher transformation temperature than the remainder of the glass in the parison. Additionally, the interior surface of the parison may be treated by a material producing active gases so that a compressive layer is produced on the internal surface of the final glassware article, at least partially balancing the compressive layer in the outer surface of the glassware article.
A method of making an article of glassware comprising the steps of forming a parison from a gob of molten glass in a blank mould, allowing the outer surface of the parison to reheat when the parison is no longer in contact with the blank mould, forming the article of glassware from the reheated parison in a blow mould, and thereafter cooling the formed glassware article, wherein the outer surface of the parison is treated during the reheating step in a manner which will cause the glass in the outer surface layer of the formed glassware article to be in a state of compression.
A method of making a glass container comprising the steps of forming a parison from a gob of molten glass, applying a glaze to the outer surface of the parison, forming from the parison a glass container the outer surface of which is constituted by the glaze, and thereafter cooling the formed glass container to obtain a glass container the outer surface of which is in a state of compression.
A method of making a glass container comprising the steps of forming a parison from a gob of molten glass, treating the glass in the surface of the parison to change the chemical composition of the glass in the surface of the parison such that the glass in the surface of the parison has a higher transformation temperature than the remainder of the glass in the parison, forming a glass container from the treated parison and thereafter cooling the formed glass container to obtain a glass container of which the outer surface is in a state of compression.
A method of making a glass container comprising the steps of forming a parison from a gob of molten glass, applying a glaze to the outer surface of the parison, treating the glaze to change the chemical composition of the glaze such that the glaze has a higher transformation temperature than the glass from which the parison was formed, forming a glass container from the treated parison and thereafter cooling the formed glass container to obtain a container the outer surface of which is in a state of compression.
Dependencies are inferred from the claim text.