Patent GB-863090-A (GB)
Title: Method and apparatus for melting and feeding heat-meltable materials
IPC: C03B37/081
Filed: 1958-12-22
Abstract: 863,090. Electric melting receptacles. OWENS-CORNING FIBERGLAS CORPORATION. Dec. 22, 1958 [Dec. 30, 1957; Nov. 17, 1958], No. 41368/58. Class 39 (3). [Also in Groups XXIII and XXXV]. In a process for the manufacture of fibres of glass or other heat-meltable material, the material in solid form is supplied to an electrically heated chamber wherein it is melted and then flows to a heated feeder from which it is removed through orifices in the form of fibres and the rate at which the solid material is electrically heated to melting point is governed by the level of molten material in the feeder. Glass cullet or marbles 88 are supplied from a hopper 64 with a reduced lower end 68 terminating in a cage 72 with spaced rods 78 converging in a discharge port 80 over an opening 82 in a plate member 50 under which the melting chamber 52 is secured by flanges 57 between the plate 50 and side walls 46 of a refractory chamber 48. The chamber 52, of platinum, rhodium or like material capable of withstanding high temperatures, has canted end walls 56 with lower end orifices 62 and converging side walls 54, the bottom wall 55 being formed with orifices 59 by bending up slit strips 63 so that molten glass 98 can flow freely into the feeder 34. The feeder 34, also of platinum or like material, is mainly rectangular and the slightly converging side walls have flanges 35 for supporting the feeder between refractory blocks 32, 40. The floor 36 of the feeder is provided with a plurality of projections 38 with orifices through which the molten glass 98 is drawn as streams 39. The chamber 52 and feeder 34 are themselves used to provide the heat for softening and melting the marbles 88 and for maintaining the molten glass 98 at the required temperature, the end walls of the feeder 34 being provided with connector terminals 120, 122 secured to clamp couplings 124, 126 and the chamber 52 having the edges of the flanges 57 secured to bus bars 60, 61 by clamps 58, the bars 60, 61 and clamps 58 being cooled by fluid through pipes 116. A metal heater strip 136 is additionally welded to and supported in the upper part of the feeder 34. As shown in Fig. 6, the flanges 57 are connected through conductors 104, 108 with the secondary 110 of a transformer 112 and the terminals 120, 122 through conductors 128, 130 with the secondary of a transformer 134, each transformer supplied by power lines L 1 , L 2 . To regulate the temperature of the glass 98 in the feeder 34, a thermocouple 140 secured to a side wall thereof is in circuit with an amplifier 142 and an adjustable regulator 144 to supply current to a saturable core reactor 138 in the power line to the transformer 134 to modify the impedence and adjust the current flow through the feeder 34. To increase or decrease the flow of material from the chamber 52 as the molten glass 98 in the feeder 34 is withdrawn, a probe bar 148 is provided with its tapered extremity 152 just below the required level of glass. A difference in potential between the bar 148 and the material in the feeder 34 is established by connections to a transformer 154 through a voltage divider 156 with an adjustable connecting member 158 to the terminal 122. A coupling transformer 160 in circuit with the probe 148 impresses a current signal therefrom to an amplifier 162, regulator 164 and saturable core reactor 166 in the primary circuit to the transformer 112 so that the flow of current through the chamber 52, and therefore the viscosity of the molten glass therein, is regulated by the level of the glass 98 in the feeder 34. In a modification, not shown, the melting chamber and the feeder of similar shapes are physically linked by welded on continuations of the side walls of the melting chamber splayed out to form a cover for the feeder, which is welded thereto, the glass flowing through a narrow restricted passageway. A screen of V-shaped perforated metal is also welded to the top flanges of the feeder to retain half-melted material. The electrical heating arrangements are similar, the cover and screen also assisting in heating the molten glass, but in addition to the probe with tip at the required level of molten glass in the feeder, two further probes are included, one with tip well above and one with tip well below the required level, each in a circuit including a visible and/or audible signal to indicate too high or too low a level of the glass.