Patent ID: 8042361

Claim:
An improved apparatus for forming sheet glass, wherein the apparatus comprises an inflow pipe for delivering molten glass, a trough for receiving molten glass that has sides attached to a wedged shaped sheet forming block that has downwardly sloping sides converging at a bottom of the wedge such that a glass sheet is formed when molten glass flows over the sides of the trough, down the downwardly sloping sides of the wedged shaped sheet forming block and meets at the bottom of the wedge, wherein the improvement comprises: a) a first inflow end compression insert inserted into a first cavity at an inflow end of the forming block, shaped to apply at least a portion of an inflow end compression force at an inflow end compression surface at zero cavity depth, wherein the first inflow end compression insert has a higher resistance to thermal creep than the forming block and a cross-sectional area that maintains a force at a bottom of the first cavity; and b) a second far end compression insert inserted into a second cavity at a far end of the forming block; such that a longitudinal compressive force is applied to a bottom of the first cavity and a bottom of the second cavity to counteract a thermal creep deformation effect of a gravitational force from a weight of the forming block such that a thickness profile of a glass sheet remains substantially constant.