Methods and apparatus for reducing stress variations in glass sheets produced from a glass ribbon

摘要

In a vertical glass drawing process, an edge guiding assembly (33) located between a glass forming apparatus (41) and a glass sheet separating apparatus (20) reduces horizontal motion of the glass ribbon (13) from which the glass sheets (11) are removed and results in the reduction of the difference in stress levels between the top and bottom edges of a glass sheet (11) made by the process. The edge guiding assembly also provides a reduction of the variation of stress levels between successive sheets of glass made by the vertical drawing process.

主权项

1. A method for making a sheet of glass by a vertical drawing process comprising:
a. forming a glass ribbon using a forming assembly, said ribbon having a central region and two edge regions, each of which has a first side and a second side; b. successively removing sheets of glass from the glass ribbon using a separating assembly; and c. guiding both the first and the second side of each of the ribbon's edge regions with an edge guiding assembly, the edge guiding assembly being located below the forming assembly and above the separating assembly at a location below that at which the glass of the glass ribbon has passed through its glass transition temperature range;wherein:
(i) the edge guiding assembly contacts the edge regions of the glass ribbon; (ii) in addition to the edge guiding assembly, one or more pulling rolls contact the edge regions of the glass ribbon; and (iii) a population of 50 sequential sheets of the successively removed sheets of glass have a lower standard deviation in stress values in at least one location as compared to a population of 50 sequential sheets produced under the same conditions but without the edge guiding assembly.