Abstract: A forehearth (20) for cooling glass from a melting furnace as it flows to a feeder bowl (28) from which it is discharged to a forming machine. The forehearth is in the form of an elongate, horizontally extending insulated trough (26) with a roof formed by a longitudinally extending series of roof block elements (30), each of which is of one-piece construction and extends completely across the width of the insulated trough. The downwardly facing surface of each roof block element is contoured to incorporate concave portions (30a, 30b) near the edges of the forehearth, a concave portion (30c) above the center of the forehearth and convex portions (30d, 30e) separating the center concave portion from the side concave portions to substantially impede heat transfer between the side concave portions and the center concave portion.

Abstract: A forehearth (20) for cooling glass from a melting furnace as it flows to a feeder bowl (28) from which it is discharged to a forming machine. The forehearth is in the form of an elongate, horizontally extending insulated trough (26) with a roof formed by a longitudinally extending series of roof block elements (30), each of which is of one-piece construction and extends completely across the width of the insulated trough. The downwardly facing surface of each roof block element is contoured to incorporate concave portions (30a, 30b) near the edges of the forehearth, a concave portion (30c) above the center of the forehearth and convex portions (30d, 30e) separating the center concave portion from the side concave portions to substantially impede heat transfer between the side concave portions and the center concave portion.

Abstract: A forehearth (20) for cooling glass from a melting furnace as it flows to a feeder bowl (28) from which it is discharged to a forming machine. The forehearth is in the form of an elongate, horizontally extending insulated trough (26) with a roof formed by a longitudinally extending series of roof block elements (30), each of which is of one-piece construction and extends completely across the width of the insulated trough. The downwardly facing surface of each roof block element is contoured to incorporate concave portions (30a, 30b) near the edges of the forehearth, a concave portion (30c) above the center of the forehearth and convex portions (30d, 30e) separating the center concave portion from the side concave portions to substantially impede heat transfer between the side concave portions and the center concave portion.

Abstract: Molten glass entering from a refiner is conditioned, in an optimum operation, such that its temperature along the center of the flowing glass just in advance of its entry into the feeder, will be of equal temperature near the surface near the bottom and intermediate these two points. A tri-level thermocouple is positioned along the center line at approximately nine inches from the feeder for monitoring these temperatures, and to serve as an aid to the operator in controlling the actual glass temperature. Positioned at opposite sides of the forehearth, approximately eight inches from the center line, are tri-level thermocouples. The three couples will be positioned at the same relative depths as those at the center line. The center thermocouple on the right side will have its output used as the control temperature for a temperature override circuit connected to the electrodes.