GB182805A - Improved process for the manufacture of sheet glass - Google Patents

Abstract

182,805. Rowart, E. July 11, 1921, [Convention date]. Drawing.-In a process of drawing glass in continuous sheets, the width of the sheet, is preserved by drawing the edges from metal which issues from channels in refractory blocks, and means are provided for regulating the temperature and consistency of the body of the metal and the temperature of the sheet as it is drawn upwards. The metal flows from a tank 1, Fig. 1, under a floating bridge 4 into a forehearth 2 where the depth of metal is small compared with that in the tank. The position of the bridge 4 can be adjusted in order to regulate the condition of the metal in the forehearth. The drawing chamber is formed by an open-ended box or casing 12 of refractory material which is adjustably supported on walls 8 extending downwards from the crown of the forehearth, a second chamber 16, which contains the drawing-apparatus, resting on the casing 12. The drawing- chamber proper 14, is formed by walls 13 in the interior of the chamber 12 which are separated at the top and extend downwards to the surface of the metal, thus delimiting an area of metal from which the sheet is drawn. At the sides of the chamber 14 are adjustable shields 18, Fig. 7, which control the extent to which the hot gases circulate over the side portions of the metal and thus assist in regulating the temperature of the metal in the drawing-area. In front of the shields are " plungers " 24 consisting of blocks of refractory material which dip to an adjustable extent in the metal. A " plunger " has a recess 27 the lower wall of which is wedge-shaped, and is perforated with a passage 25 through which passes the metal from which the edges of the sheet are formed. In operation, a bait is lowered through the space 35 at the top of the drawing-chamber and after the metal has adhered, is drawn upwards into the chamber 16 in the usual manner. The bait has depending portions at its ends which enter the recesses in the " plungers " 24 and draw the metal from the passages 25. The edges of the sheet are thus drawn from separate portions of metal which unite with the body of the sheet as they leave the passages 25. The temperature of the sheet is regulated as it is drawn upwards by means of metal coolers 21<1>, contained in the drawing-chamber 14, through which water is circulated. Curtains or shields of refractory material may also be used to control the radiation from the surface of the sheet. In a modification, shown in Fig. 2, the metal from which the sheet is drawn is contained in a box-like structure 37 of refractory material which dips into the metal and communicates with the body of the tank through grooves and passages 39, 40. Metal passes through these grooves into the interior of the structure, thus obtaining a comparatively small volume of metal at the temperature necessary for drawing.