Method and apparatus for making a glass sheet with controlled heating
First Claim
1. A method for making a glass sheet by an overflow process using a forming body having a top, a first side surface, and a second side surface joining the first side surface at a root, the method comprising flowing molten glass over at least part of the first side surface to form a first glass ribbon, flowing molten glass over at least part of the second side surface to form a second glass ribbon, and fusing the first glass ribbon and the second glass ribbon at the root to form a third glass ribbon, wherein:
- (A) the first side surface is radiatively heated by a first side heat plate which is heated by a first array of separately monitored and controlled heating elements located behind the first side heat plate;
(B) the second side surface is radiatively heated by a second side heat plate which is heated by a second array of separately monitored and controlled heating elements located behind the second side heat plate; and
(C) the heating power of the heating elements of the first and second arrays are controlled such that if the heating power of a malfunctioning heating element or elements in the first and second arrays decreases to a threshold level, the heating power of the adjacent, functioning heating element is increased, such that an undesirable thermal gradient does not form between a part of the side surface across from the malfunctioning heating element or elements and a bulk of the forming body under the part of the side surface across from the malfunctioning heating element or elements.
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Accused Products
Abstract
A method and apparatus for forming a glass sheet using a fusion down-draw process, wherein the heating powers of the heating elements are managed such that in case of a failure of one heating element, the heating power of the adjacent heating element is immediately increased. The method decreases the thermal stress the forming body is exposed to due to the failure of the heating element.
18 Citations
16 Claims
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1. A method for making a glass sheet by an overflow process using a forming body having a top, a first side surface, and a second side surface joining the first side surface at a root, the method comprising flowing molten glass over at least part of the first side surface to form a first glass ribbon, flowing molten glass over at least part of the second side surface to form a second glass ribbon, and fusing the first glass ribbon and the second glass ribbon at the root to form a third glass ribbon, wherein:
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(A) the first side surface is radiatively heated by a first side heat plate which is heated by a first array of separately monitored and controlled heating elements located behind the first side heat plate; (B) the second side surface is radiatively heated by a second side heat plate which is heated by a second array of separately monitored and controlled heating elements located behind the second side heat plate; and (C) the heating power of the heating elements of the first and second arrays are controlled such that if the heating power of a malfunctioning heating element or elements in the first and second arrays decreases to a threshold level, the heating power of the adjacent, functioning heating element is increased, such that an undesirable thermal gradient does not form between a part of the side surface across from the malfunctioning heating element or elements and a bulk of the forming body under the part of the side surface across from the malfunctioning heating element or elements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification