| 摘要 |
<p>ELECTRICALLY HEATED GLASS FOREHEARTH The forehearth provides a channel for the flow of molten glass from a tank type furnace to a feeder bowl or the like in order to feed gobs of glass to one of several glassware forming machines provided with glass from a single furnace tank. The forehearth channel has sets of electrodes arranged in each of three discrete zones along the forehearth channel, with the center electrode being at a predetermined and controlled potential with respect to electrodes located at the upstream and downstream ends of each zone. The electrode associated with the downstream end of one zone is also used as the upstream electrode associated with the adjacent zone, and the glass is heated by virtue of the fact that these electrodes are immersed in the glass, with an A. C. single phase voltage being impressed thereon. Individual transformers are provided for each of the zones, and controllers for the primary of each transformer operate in response to current sensed at the downstream end of each zone, the voltage at the secondary of each transformer, and also in response to a correction signal provided for each controller and derived from a glass level measuring device associated with the upstream end of the forehearth itself.</p> |
