Patent ID: 8474286

Claim:
A method of supplying a constant flow of glass to a glass forming process using an apparatus comprising a downcomer pipe arranged to receive molten glass flow from an upstream device and configured for controlling the flow of molten glass, a forming block configured to form molten glass into a glass sheet, an inflow pipe configured to receive molten glass flow from the downcomer pipe and deliver the molten glass to the forming block, a first heating element and a second heating element positioned on an outside of the downcomer pipe, a first thermocouple arranged to measure a temperature of a glass stream through the downcomer pipe at an inflow end of the first heating element, a second thermocouple arranged to measure a temperature of the glass stream at an outflow end of the first heating element and at an inflow end of the second heating element, and a third thermocouple arranged to measure a temperature of the glass stream at an outflow end of the second heating element on the downcomer pipe, comprising the steps of: a) flowing a stream of molten glass through the apparatus at a mass flow rate; b) adding a substantially constant total energy input to the stream of molten glass with the first and second heating elements; a) detecting a change in a difference between the temperature of the glass stream measured by the first thermocouple and the temperature measured by the third thermocouple to determine an error in the mass flow rate; and b) changing the temperature measured at the second thermocouple by adjusting the respective energy input of the first and second heating elements, while maintaining the total energy input constant such that the mass flow rate is maintained at a substantially constant value.