Patent ID: 8720225

Claim:
A method for forming sheet glass of constant thickness in a downdraw apparatus, wherein the apparatus includes a forming block and an inflow pipe for delivering molten glass to the forming block, the forming block comprising a trough for receiving the molten glass and downwardly sloping sides converging at the bottom of the forming block, such that a glass sheet is formed when the molten glass overflows the trough and flows down the downwardly sloping sides of the forming block and meets at the bottom of the forming block, the method comprising the steps of; a) determining a first relationship between forming block shape deformation and sheet glass thickness distribution; b) determining a second relationship between applied forces and the shape of the forming block; c) measuring a thickness profile of a glass sheet manufactured using the downdraw apparatus at a time during a manufacturing campaign; d) calculating a deformed shape of the forming block from the glass sheet measured thickness profile and the first relationship; e) based on the calculated deformed shape of the forming block and the second relationship, determining at least one change in at least one force applied to the forming block required to change a shape of the forming block to produce a more uniform thickness distribution; and f) applying a corrective force to the forming block based upon the calculated the at least one change in at least one force applied to the forming block from step (e).