GB1154153A - Method for Cooling Glass - Google Patents

Abstract

1,154,153. Annealing glass ribbon or sheet. PITTSBURGH PLATE GLASS CO. 6 June., 1966 [16 June, 1965], No. 25198/66. Heading C1M. [Also in Division F4] In the cooling of glass ribbon or sheet in a vertical or horizontal annealing lehr, temperature profiles, as TP-1, TP-2, TP-3, are established by measurement of the temperature of the glass along a straight line normal to the edge of the ribbon and the difference between the temperature of the centre point C 1 , C 2 and the temperature of any point a 1 , a 2 between 13 and 23% of the width of the ribbon in from the edges is continuously maintained between 0‹ and 20‹ F. more than the difference between the same points c and a when the glass was at or above the upper limit of the annealing range and this temperature difference is maintained at least until the temperature of the glass falls below 300‹ F. A suitable soda-lime-silica glass is disclosed, with temperature ranges and measurements. As in Fig. 6, a glass ribbon 90 is passed on rollers 99 through an annealing lehr having insulation 100, surface heating elements and edge heaters 98 and the temperature profiles are measured by sensing devices 102, and from which data the edge heaters 98 can be controlled. The edge heaters may be electrical with separate elements across both side edges or with a continuous element bent to extend across both face edges or as shown in Fig. 5, heaters 80 extending across both face edges consist of a combustible air-gas mixture ignited through orifices 81 with shields 82 either side to prevent blowout.