Patent GB-253894-A (GB)
Title: Improved method of and apparatus for making a composite strand or covered wire
IPC: H01B13/08
Filed: 1926-06-09
Abstract: 253,894. Slade, E. June 17, 1925, [Convention date]. Wire cores, covering by winding and wrapping. - A composite strand or a covered wire e.g. a strand adapted to be woven into fabric for a brake lining, or an electrical conductor, is formed by loosely applying a covering to a core and subsequently rotating a binding element under tension about the covered core at a point in advance of the point of application of the covering, while the covering is held against rotation at a point disposed rearwardly of the binding point. By this means the binding element twists the covering into convolute form. In forming an electrical conductor a .copper wire core 3 is drawn by rollers 10 from a supply reel 4 through a guide 40 to the wrapping mechanism which comprises a bridge element 25, Fig. 6, in which are adjustably mounted dies 26. 27, 29 to receive the core 3 and a number of asbestos strips, and preferably one strip of vegetable fibrous material of high tensile strength, the strips being held against rotation on the entry side of the dies by bars 26<1>, 27<1>, 29<1>. The asbestos strips 11, 13 and strip 15 of vegetable fibre are led prior to the folding operation through a trough containing an impregnating solution, preferably a solution known as " hermatite," containing mitrocellulose and a non- oxidizing oil, the superfluous solution being removed by projecting wipers 30, 32 and by sheets of felt 35<1> between which the strips pass. The strips are guided from the dies on to the core 3 by arms 28, adjustable with respect to the bridge 25, the wrapped core being led through a hollow shaft 43 which carries the winding head 48 and is rotated by means of a motor 46. The bobbin 52 for the binding material is frictionally engaged by the shaft 43 by means of an adjustable stuffing box 53 and leather washer and the material 57 is guided on to the wrapped core by a pulley 58 and an adjustable guide plate 49 which rotates with the shaft 43 and head 48. The wrapped and bound core, or conductor, Fig. 16, may then be led directly to compressing dies 60 or through a tank 62 of coating material and thence to the dies, the superfluous coating material being removed by passing the conductor through wiper dies 60<1>. To prevent setting up undue stresses in the conductor or in the apparatus due to jamming of the conductor in the compressing dies the dies 60 are mounted upon pivotally supported frames 64 held in the vertical position by springs 62<1>, movement of the frames 64 operating a lever 65 to stop the motor 46 and to brake the winding head 48. The conductor upon leaving the dies 60 preferably passes through a dryer and then through a trough wherein it is dusted with asbestos floats or powdered mica. The braking device for the winding head 48 preferably comprises a pivoted band 67, Fig. 9, which is normally held out of contact with the head by the hooked end of a lever 66, but which when the lever 66 is actuated, by movement of the lever 65, is forced into engagement with the head by a spring 69. A pawl 76 carried by the head 48 engages a ratchet 73 provided upon the bobbin 52 to prevent rotation of the bobbin upon stoppage of the winding head. In making the strand for use in a brake lining a thin wire core is covered with asbestos strip and the binding element preferably has a thin metallic core, the wrapping material preferably being moistened before being wrapped around the core, and the machine, in this form, is provided with means for holding the strip of wrapping material out of contact with the moistening device upon stoppage of the machine. The strand, or wrapped and bound core is coated with a waterproofing &c. solution, preferably an oxidizing oil, an agitating device operated from a countershaft driven by the machine motor being provided for stirring the solution.