Patent GB-674014-A (GB)
Title: Filament forming apparatus
IPC: D01D5/00
Filed: 1949-11-23
Abstract: <PICT:0674014/IV (a)/1> <PICT:0674014/IV (a)/2> <PICT:0674014/IV (a)/3> <PICT:0674014/IV (a)/4> Apparatus for producing an artificial filament comprises means for supplying filament-forming material in fluid state uniformly to the exterior of a discharge element, means for setting up an electrostatic field of force between the discharge element and a filament-receiving device including a rotating electrode aligned with but spaced from and insulated from the discharge element, and a source of electrical energy, for maintaining the electrostatic field, connected to the discharge element and the rotating electrode, whereby the filament-forming material is caused to migrate from the discharge element to the electrode in the form of a continuous filament which is removed from the space between the discharge element and the electrode by the rotation of the latter. The term "filament" includes a single strand, or untwisted or fibrilliform strands, which may be solid or tubular, and ribbons. The filament may be formed from one or several filament-forming compositions.  It may have a basis of a natural or synthetic resin, cellulose ester, gelatine, glue or rubber.  Finely-divided solid inorganic or organic substances may be incorporated in the fluid composition or they may be applied as coatings to the filament during formation.  The filament may be received on a flexible band which may carry the filament through a heating zone so as to complete the setting and hardening of the filament.  When a tubular filament is to be formed the discharge element may be in the form of a hollow member which is rotated and which has air or gas supplied therethrough so that the filament will have a uniform diameter and thickness.  When the filament is to be in the form of a band or ribbon, the discharge element may have a comb-like outer end.  As shown in Fig. 1, fluid filament-forming material is applied to the exterior of the discharge element 33 formed of electrically-conducting material and having its lower end pointed. An electrostatic field is set up between the discharge element 33 and the flexible band or belt 50, so that the fluid is formed into a continuous filament which is received upon and carried by the belt through the heating device 124.  After leaving the belt, the filament passes through gripping rollers 102, 103, and thence to a winding device.  The relative positions of the discharge element and the point where the filament is received by the band are adjustable by rack-and-pinion mechanism.  The filament-forming fluid is supplied from one or more containers 125, 126 by fluid-pressure, valves 145 being provided for adjusting the rate of flow or for adjusting the proportions in which two filament-forming fluids are mixed.  The fluid flows through pipe 41 to the discharge assembly 27. If desired, in order to prevent divergence of the lines of electrostatic force, a magnetic field may be set up between the discharge element 33 and the band.  In Fig. 1, the electromagnet 153 is in the off position, but it may be swung into position to surround the end of the element 33 and the filament which is being formed.  As shown in Fig. 3, the discharge assembly comprises a housing 28 within which is disposed the discharge electrode 33.  This electrode is surrounded along most of its length by an insulating sleeve 34.  The electrode 33 and the sleeve have a sliding fit in the bore of nut 36 which screws into sleeve 37.  Screw 38 secures the electrode in position.  Filament-forming fluid is fed into the interior of sleeve 37 through opening 40.  Tapered portions of the electrode and its sleeve extend through the opening in the bottom of the housing 28 so as to form an adjustable valve regulating the flow of fluid.  A heat exchange housing is disposed about the lower end of housing 28, and is provided with a coil 43 for heating- or cooling-fluid.  The opening at the bottom of housing 42 is of such a size as to permit the filament-forming fluid to flow along the discharge element as a film thereon.  The filament-forming fluid may be pre-charged by providing an electrode 44 within the housing 28.  This electrode is preferably in the form of a ring of conductive material provided with several inwardly-directed projections 45, Fig. 9.  The discharge electrode 33 is given the same potential as that of the pre-charge electrode 44 through connections at 35 to the source of electrical energy.  The flexible belt 50, which is preferably metallic, passes over pulley 51 in the vicinity of the discharge electrode 33.  Pulley 51 has an annular electrically-conductive portion 69 between two insulating portions 70, 71, and it also has a disc-like portion 72. The portion 69 is in electrical contact with a brush which is connected to the terminal screw 76.  Wire 77 leads to the source of electric energy.  Electrical connection of the belt to the source of electric energy may also be effected through wire 84, plug 86, and plunger 88.  As shown in Fig. 13, means are provided for applying powders or other finely-divided materials to the filament-forming material as it is being formed into a filament. A source of fluid under pressure is connected to conduits 170, 171 and these are connected to the tangentially extending ducts 172, 173 of housing 169.  These ducts have nozzles 174.  Air or other fluid under pressure is thus caused to flow with a swirling action about the discharge electrode.  Powdered material in tanks 177, 178 is stirred up with air or other fluid and is sucked into pipes 175, 176 by the flow of air in ducts 172, 173, and is then blown on to the film of filament-forming liquid on the end of the discharge electrode 33.  If desired, means may be provided for tilting the apparatus so that the portion of the belt carrying the filament is tilted slightly from the vertical direction and can thus act as a support for the filament.