GB321118A - Improvements in twin and multi-core electric cables - Google Patents

Abstract

321,118. St. Helens Cable & Rubber Co., Ltd., and Harrison, H. C. Jan. 16, 1929. Cables and conductors with identifying coverings.-A twin or multicore cable comprises conductors, each covered with insulating material which is applied in a plastic state, the insulating coverings differing in colour from each other and all the coverings being jointed together to form a unitary structure. In manufacture, the conductors may be separately insulated with coloured coverings, being then passed through adjustable roller dies before vulcanization of the coverings, the coverings being thus caused to adhere to one another. The cable may be formed by an extrusion machine having the same number of worm screws as there are different coloured insulations, the bodies of insulation being kept separate until they arrive at a common die where they are joined together. A further method of manufacture consists in passing the conductors through a longitudinal machine. In the case of a twin core cable, a sheet of vulcanized red rubber is placed on a similar sheet of black rubber, and the composite sheet is cut up into strips by passing the sheet between a roller and a series of cutting knives which, it is stated, also cause the strip of red rubber to adhere to the black rubber along the edges. Each composite strip thus formed is then opened out so as to obtain a strip one half red and one half black. The conductors are covered by passing them, with a composite strip above, and one below, them, through shaping rollers. The coverings may be cylindrical, adhering to each other side bv side so as to form a flat cable. A twin cable may consist of D-shaped cores adhering along the flat sides of the cores. In multi core cables, the outer cores may be of D-section, the inner cores being rectangular in section.