Patent GB-833417-A (GB)
Title: Producing sheet glass
IPC: C03B15/04
Filed: 1958-10-03
Abstract: 833,417. Drawing sheet glass. LIBBEYOWENS-FORD GLASS CO. Oct. 3, 1958 [Oct. 4, 1957], No. 31579/58. Class 56. In a furnace for the continuous production of window glass comprising a melting chamber, a refining chamber, a cooling chamber and a forming chamber including a working receptacle, all in end to end relation, the channel for the molten glass in the cooling chamber is of gradually decreasing depth towards the working receptacle and means are provided for sealing at least a part of the atmosphere thereabove from the atmosphere above the molten glass in the refining chamber to assist in eliminating ream in the glass. As shown, molten glass flows from the melting chamber through one or more refining chambers 21, a cooling chamber 22 with sloping floor 57 to the forming chamber 24 where the sheet 31 is drawn upwardly from the draw pot 23 and deflected over a bending roll 32 and idler roll 33 to machine rolls 35 in a flattening chamber and thence-onto rolls in an annealing lehr. A cut off bar 41 seals the passage between the chambers 21, 22 and preferably has an enlarged upper end 42 and an angled ledge 43 lying in the molten glass. As in Fig. 8, a similar sealing bar 90 may be provided between the cooling and forming chambers 22, 24, the bar being pivoted at 93 and having a curved face 91 to the ledge 94 to assist flow of glass. The depth of glass between the floor 57 and bars 41, 90 should be at least 12, 6 inches respectively, the floor being given different slopes 96, 95 if necessary to provide this clearance. Skim pockets 38 may be provided in the side walls of the refining chambers 21 and cooling air is introduced therein by pipes 40. In the cooling chamber 22 to maintain a uniform temperature in the glass, controlled insulation is used at the sides to prevent radiation therefrom, cooling air is introduced through pipes 44, 45 and a slot 49 in a through pipe 46 and cooler pipes 50 adjacent the end wall lie closer to the molten glass at the centre 52 than at the ends 53. Additionally, electrodes 55 and 56 may be provided in the side walls adjacent the end of the chamber. The draw pot 23 is supported on stools 27 in a chamber 28 heated by gas burners 29, the products of combustion being removed through passageways 70 and a duct leading to an exhaust system. The chamber 24 is sealed off from the chamber 28 by a T bar 69 between the wall 68 of the pot 23 and the lip-tile 63. The forming chamber 24 and flattening chamber 34 are substantially closed and have observation bays in the side walls through which the operating mechanisms are provided. To maintain the temperature in the back end of draw pot 23, the lip tiles 62, 63 are insulated the upright 72 of bar 69 is thin so as to radiate heat from the chamber 28 and electrodes 73 are provided, the current flowing through metal width maintaining rollers 74, 75 and across the glass at the meniscus of the rising sheet. The rollers 74 are knurled as usual, but smaller rollers 75 are placed close to the base of the rising sheet to reduce the thickness of the edges. The chamber 34 is separated from the lehr by an adjustable curtain above the glass sheet and a further curtain 791 may separate the chambers 24, 34. Gas or air is removed from these chambers by a flue with an adjustable damper plate, and by exhaust pipes 84 adjacent the meniscus 66 to maintain a quiescent atmosphere. Heaters 85, 86 and 87 may be provided and coolers 88, 89.