Patent GB-802828-A (GB)
Title: Machine and process for forming glass fibers
IPC: C03B37/085
Filed: 1956-03-13
Abstract: 802,828. Glass manufacture. GLASS FIBERS CO., L. O. F. March 13, 1956 [Feb. 16, 1956], No. 7765/56. Class 56. [Also in Group XXX] In the manufacture of fibrous glass mats, the molten glass exudes through rings of orifices in the bottom of the crucible, the advancing ends of the filaments so formed being subjected to a high velocity and temperature blast which melts the ends and draws them out into fine fibres, which are projected against a vertically moving collecting surface. As shown, crucibles 24 are arranged in a row and are fed separately and automatically with glass marbles from a hopper 49, according to the level of the molten glass in the crucible. The glass streams are drawn into filaments by rubber-covered rollers 32, 33, the filaments being aligned for presentation to the rollers by grooved guide blocks 122. The filaments then pass through grooves on the face of a guide block 34 at the entrance to a fibre forming shoot 123 which receives the hot blast from a burner 35. The fibres are sprayed at 39 with a binder and are then deposited on the upwardly moving flight 40 of a foraminous collecting chain, the space at the back of the chain being connected at 138 with an exhaust fan. The matted fibres 42 are removed at a from the descending chain and are laid upon a conveyer chain 46 of an oven in which the binder is cured and the mat is compressed to the required thickness by a top chain 48. At the exit end of the oven, the mat is cut longitudinally by one or more disc knives and the strips are rolled up for shipment. The marble feeder comprises a shoot 50 extending along the length of the hopper 49 and leading to header 51 carrying a row of tubes 59, the header being reciprocated along its length, that is, across the shoot 50 whereby the marbles are directed into the tubes 59 and continuation tubes 27. The bottom of the shoot 50 is of expanded metal through which undersized and broken marbles are rejected, this being assisted by agitator bars 69 which are connected to the reciprocating header and are pivoted at 70 to the bottom of the hopper 49. The single file of marbles within each tube 27 is retained by a pivoted escapement 73 which, when it performs a complete oscillation, releases one marble to the crucible via the pipe 28. The escapement 73 is swung counter-clockwise by a solenoid 80 and is returned by the weight of the arm 79. Current is supplied by lines 81, 82, the former being connected to an electrode 83 in each crucible, so that when the end of the electrode 83 is immersed, current passes to a longer electrode 84 and activates a solenoid 86 which maintains a switch 88, 92, 93 broken against the urge of a spring 91 to close it. When the glass level falls, the electrode 83 leaves the glass, the solenoid 86 is deenergized and the switch 88, 92, 93 is closed. This switch is in circuit with an impulse box 95 which sends impulses of about one second duration through the solenoid 80, the time between impulses being about thirty seconds. A marble is thus released to the crucible by every impulse. The crucible is of cylindrical shape and is spaced from a cylindrical jacket, the burners 115 being directed tangentially into this space. A suitable glass composition is, in weights per cent, SiO2, 47-60; B2O3, 9-15; R2O3 (Al2O3 with traces of TiO 2  and Fe 2 O 3 ),5-10À5; Na 2 O, 8-13; K 2 O,2-5; CaO, 1-4; MgO, 0À05-1À0; BaO, 2-6; ZnO, 2-6 ; CaF 2 , 1À0-3. Specifications 590,258 and 599,199 are referred to.