Verfahren und Vorrichtung zur Herstellung von Glas in Bandform

摘要

In a process for drawing a continuous ribbon of glass from a bath of molten glass in which the sides of the ribbon are cooled in a zone spaced from the surface of the bath, increases or decreases from the desired thickness of the ribbon transversely thereof are measured and in accordance thereto increasing or decreasing heat is respectively supplied to correspondingly transversely disposed regions of the bath spaced from the base of the ribbon but in the zone of ribbon formation. A conventional glass sheet-drawing apparatus, Fig. 1, in which a ribbon of glass 30 is drawn from a bath of molten glass 28 by rolls 46 and which has coolers 42, 43 within a drawing chamber 12 which is defined by L-blocks 32, 34, has one of the coolers 42 modified by the addition of an electric heating element 60 the temperature of which is varied in response to variations in the thickness of the glass ribbon 30 as determined by the readings of a measuring device 166 which comprises an X-ray generator 168 and a crystal pick-up device 70. The X-ray generator 168 and crystal pick-up device 70 are optically aligned and mounted on a pair of commonly driven screw members 72 for transverse movement in unison with respect to the ribbon. The cooler 42, Fig. 3, comprises rectangular section metal tubing 58 through which water flows, the heating element 60 and a channel member 68 which serves to carry lead wires 66 which connect a plurality of individual heating coils 60a, 60b, 60c &c. to individually controlled electric power supplies. The element 60 is partially thermally and completely electrically insulated from the cooler 42 by a shield 64. In another embodiment, Fig. 4, a cooler 142 which is lower case h-shaped is used. A block diagram of an electric circuit for controlling the heating coils 60a, 60b &c. and the speed of the drawing machine is disclosed. Gas burners may replace the heaters 60. Gas jets 320, Fig. 8, may be used to control the air currents within the drawing chamber 12.