GB1173447A - Improvements in Magnetic Cores - Google Patents

Abstract

1,173,447. Making transformer cores; jointing. TELCON-MAGNETIC CORES Ltd. 26 July, 1967 [27 July, 1966; 19 May, 1967], No. 34371/67. Headings B3A and B3V. [Also in Division H1] A magnetic core, e.g. for a transformer, is formed from two C-shaped core parts 1, 2 the ends of which are provided with interdigitating projections 6-11 forming in the core a zig-zag pattern of butt-joints such that no two joints in adjacent projections lie in the same transverse plane, and the core parts are separable, without dismantling either part, and capable of reassembly round a coil or coils. Adjacent laminations may overlap by a minimum of twice a lamination thickness, but preferably four times that thickness. The core may be made in the following steps: (1) A sheet of, e.g: grain-oriented magnetic material, non-oriented steel, or nickel-iron, is formed into a coil (Fig. 3, not shown); and (2) is severed longitudinally along a diameter (Fig. 4, not shown) to produce two sets of semicircular laminations which are then (3) separated magnetically; and (4) individually re-constructed, to form staggered joints, about an insulating mandrel about which a magnetic field is provided to hold the laminations together (Fig. 6, not shown). (5) The resulting preform is then pressed to its substantially rectangular shape. The ends of the laminations may be coated with plastics, and the two core halves assembled while the coating is wet or after drying. Alternatively, a varnish, lacquer, paint, cold- or thermo-setting, e.g. epoxy, resin may be used, and may bond the core parts together; Oil may be used as a lubricant in assembling the parts. The parts may be made rigid by applying a bonding material to their sides, and in this the lubricant may be a silicon-based resin or plastics. The parts may be annealed during some operations, or heated during assembly.