Patent GB-750677-A (GB)
Title: Improvements in apparatus for processing heat-softenable material
IPC: C03B5/26
Filed: 1954-07-27
Abstract: 750,677. Making fibre glass. OWENSCORNING FIBERGLAS CORPORATION. July 27, 1954 [Aug. 3, 1953], No. 21931/54. Class 56  Apparatus for making fibrous glass comprises a receptacle adapted to contain and flow molten glass therethrough to a forehearth provided with a series of feeders spaced along the length thereof for :feeding molten glass and means for attenuating the molten glass to fibres, the forehearth being connected at a place interme-' diate its ends with the receptacle so that molten glass flows into the forehearth at a zone intermediate its ends and then in both directions to the feeders located along the length of the forehearth. As shown in Figs. 1 and 2, the forehearth 20 is joined to the furnace 10 by a passage 18, the glass batch 12 being received in a section 14 of the furnace 10 which is fired by fuel gas or oil to render the batch 12 molten and flowable, and the molten material flows forwardly through the furnace which mixes and fines it. The bottom surface 23 at the entrance, to the passage 18 is level with the furnace bottom and is joined to the main conveying and fining channel 21 in the passage 18 by an inclined wall 22 and a skimmer block 24 is disposed as shown adjacent the connection with the furnace. The molten glass in the channel 21 is maintained at the required temperature by independent burners 70 each supplied with a combustible mixture through a pipe 72 having a valve 74 for controlling the mixture to the semi-spherical burning chamber 76, the chambers 76 being spaced along and just above the channel 21. The channel 21 leads to the centre of a channel 28 in the forehearth 20 along which the molten glass flows to feeders 26 each having a plurality of orifices through which streams S of the glass are drawn by pull rolls 30 from whence filaments F are guided by a guide means 46 into the gaseous blast from a series of burners 35 which attenuate the filaments F into a mass M of fibres which are collected on a conveyer 48 having a suction chamber 50 adjacent. The fibre attenuating means is comnrised in an enclosure 32 and the burners 35 are of the internal combustion'type. The channel 28 in the forehearth is provided with a plurality of independent burners 55, each with supply pipe 64 and valve 65 for regulation of the mixture to the semi-spherical burning chamber 59, so that the viscosity of the molten glass can be controlled and so that if one feeder 56 requires replacement or repair, the burners adjacent thereto may be regulated to cause temporary congealing in the zone of the feeder while it is removed, the remainder of the feeders, or at least the feeders on the other side of the channel 21, remaining in use. Similarly, if a feeder adjacent the end of channel 21 requires to be removed the burners 70 may be regulated to just congeal the glass at that end of the channel so that the furnace need not be cooled. At each end of the channel 28, outlets 58 are provided having an inclined' wall 60 for maintaining a proper and constant depth of glass. Vents or stacks 62 allow for the escape of burned gases from the burners. In the modified construction shown in Fig. 5, the connecting passage, 100, between the furnace 10 and the transverse forehearth section 20<SP>1</SP>, is formed with a channel 102 with a deepened zone 104 adjacent the furnace and the skimmer block 105 is of platinum or other heat reistant material. Radiant burners 70<SP>1</SP> are provided as before with separate valves 103 and one burner 110 is disposed, adjacent the skimmer block 105, at an angle to direct the flames towards the block 105 and prevent any congealing in the restricted passageway 107 under the block. In either construction, the glass passing through the restricted passage 25 or 107 tends to be at a lower temperature adjacent the bottom wall 23 or 104 so that dross or impurities tend to remain in this area and an opening 80 or 114 is provided through which the waste material may be discharged. As shown in Figs. 1 and 6, a tubular member 82 has a side opening 84 in which is secured a bracket 85 with upstanding lugs 86 having slots 87 for reception of a trunnion pin 88 secured to a lever 90. The arrangement of the pin 88 is such that the lever 90 is unbalanced and normally lies horizontally resting on an upstanding portion 92 of the bracket 85. The waste glass flows through the outlet 80 in a stream R. which impinges on the pad 91 of the lever 90 extending into the chamber 82, until the solidified mass or gob 94 weighs sufficient to overbalance the lever 90 to the position shown in Fig. 6 when the gob 94 slides off and is received in a waste receptacle 95, the lever 90 immediately swinging back to the horizontal position. As shown in Fig. 5, a lever 116 is pivoted on a shaft 117 between brackets 118 secured to the tube 82<SP>1</SP>. A member 120 secured to the end of the lever 116 'in the tube 82<SP>1</SP>, has a cooling chamber 124 with flexible inlet and outlet tubes 125 and 126 for a cooling fluid to cool the upper surface 122 on which the gob forms. A counterweight 127. on the other end of lever 116 is adjustable by a screw 128 to maintain the lever normally horizontally. To assist removal of the gob when the lever is tilted, a pipe 129 is provided through which a jet of air may be projected across the surface 122, the tilting of the lever 116 actuating a microswitch which controls a valve in a housing 130 for projecting the air jet.