GB368304A - Improvements in the manufacture of loaded electric signalling conductors - Google Patents

Abstract

To avoid straining the loading material during the annealing of a continuously-loaded conductor, a spacer of thermoplastic material, such as guttapercha, which vaporizes during the annealing operation is disposed between the conductor and the loading tape. The loaded conductor may be annealed in an atmosphere of nitrogen, but preferably, to avoid the formation of soot on the walls of the annealing furnace due to the decomposition of the spacer, the annealing operation is performed in an atmosphere consisting of an inert gas, such as nitrogen, containing a gas, for example water vapour, in which there is combined oxygen capable of oxidizing the carbon present in the spacer. The water may be introduced into the furnace in drops or in the form of steam, or water may be sprayed in with the nitrogen. In modified arrangements, the loaded conductor may be wetted or the spacer soaked in water prior to the heat-treatment. To prevent escape of poisonous gases generated during the annealing operation, a furnace of the kind described in Specification 368,493, [Group XXXVI], may be employed, or the gases may be ignited as they issue from the furnace. Specification 282,504, [Class 36, Electricity, Conducting &c.], also is referred to.