Defect control in the making of sheet glass by the fusion process
AssigneeCorning Incorporated
InventorsPhilip M. Fenn, John T. Fisk, Randy L. Rhoads
Life of this patent
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Abstract
A molten glass delivery system for use in producing sheet glass by a fusion process is provided. The delivery system includes a first conduit (9) which surrounds a portion of a second conduit (19) with a free surface (21) of molten glass (31) being formed between the two conduits. The first (9) and second (19) conduits are positioned with respect to one another so that the spatial relationship between the exit end (20) of the second conduit (19) and the free surface (21) results in neither substantial numbers of devitrification defects (27, 29) nor substantial numbers of blister defects (35) in finished sheets of devitrification sensitive glass, e.g., high silica LCD glass.
Claims20
A molten glass delivery system for use in producing sheet glass by a fusion process comprising:
- (a) a first conduit which has a first characteristic cross-sectional dimension;
- and
- (b) a second conduit which has an exit end and a second characteristic cross-sectional dimension;
- wherein:
- (i) the first conduit receives molten glass from the second conduit;
- (ii) a portion of the first conduit surrounds a portion of the second conduit;
- (iii) the first characteristic cross-sectional dimension is larger than the second characteristic cross-sectional dimension so that a free surface of molten glass is formed between the first and second conduits;
- and
- (iv) the first and second conduits are positioned relative to one another so that the spatial relationship between the exit end of the second conduit and the free surface of the molten glass results in neither substantial numbers of devitrification defects nor substantial numbers of blister defects in the finished sheet glass for a glass that is devitrification sensitive.
A method for providing molten glass to apparatus which produces sheet glass by a fusion process, said method comprising:
- (a) providing a first conduit which has a first characteristic cross-sectional dimension;
- (b) providing a second conduit which has an exit end and a second characteristic cross-sectional dimension, said second characteristic cross-sectional dimension being smaller than said first characteristic cross-sectional dimension;
- (c) nesting a portion of the second conduit within a portion of the first conduit;
- (d) flowing molten glass out of the second conduit and into the first conduit, said molten glass forming a free surface between the first and second conduits;
- and
- (e) selecting the relative locations of the first and second conduits so that the spatial relationship between the exit end of the second conduit and the free surface of the molten glass results in neither substantial numbers of devitrification defects nor substantial numbers of blister defects in the finished sheet glass for glass that is devitrification sensitive.
Dependencies are inferred from the claim text.