Electric boosting control for a glass forehearth

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. The temperature override circuit will have a set-point temperature indicator whose level is selected by the operator and this selected level is compared to the output of the middle side electrode. Typically, the operator will select the set-point temperature to be that temperature which it is desired to achieve relative to the center line thermocouple temperature indicators. Ideally, all of these temperatures will be in agreement and the temperature of the glass will then be that at which optimum working properties of the glass will be attained.