GB616536A - Improvements in and relating to electro-magnetic induction apparatus - Google Patents

Abstract

616,536. Making transformer cores. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 7, 1945, No. 23133. Convention date, Sept. 11, 1944. [Class 83 (ii)] [Also in Group XXXV] In making a laminated magnetic core member, a number of magnetic sheets are stacked, gripped at one end where their ends are suitably arranged, and then bent so that the stack takes the shape of part of the core. To form a U-shaped core member, strips with ends cut diagonally and having holes at each end, at different distances from the different ends are stacked in layers, the strips in each layer being reversed compared with those of adjacent layers, Fig. 5. The strips decrease in length from top to bottom so that when the stack is made U-shaped the ends come generally together. To bend the stack, a pin 19 is passed through the aligned holes at one end which is clamped between two mandrels 21, 22, Fig. 6, which are then rotated counter-clockwise on a shaft 23, the sheets being bent round mandrel 21 by their engaging a stop 24. A pin 25 is then pushed through the holes having centre line at the free end of the stack, and through mandrels 21, 22 and holes in the clamped end of the stacks to replace pin 19. Mandrel 26 is then clamped to hold the second end of the stack, which is annealed, alone or assembled with a similar core half, Fig. 8. After annealing, rivets 27 may replace pin 25 and the U-shaped parts are placed in pairs round a winding 7, Fig. 10. The diagonal butt-joints of adjacent layers may, Fig. 12 (not shown), or may not, Fig. 9 (not shown), cross. One of the U-shaped core parts may be made from strips of uniform length so that the general line of the joints is not perpendicular to the plane of the lamination, Fig. 14 (not shown). To increase the ease of assembly, one U-shaped part 2 may have plates 34 riveted to it to form guides for the other part 3, Fig. 13. Specification 621,675 is referred to.