GB1104772A - Transformer cores and method of making same - Google Patents

Abstract

1,104,772. Making transformer cores, bending, shearing. TELCON-MAGNETIC CORES Ltd. 18 March, 1966 [30 March, 1965], No. 12025/66. Headings B3A, B3E and B3W. [Also in Division H1] A method of making transformer cores comprises cutting lengths of magnetic material from a strip thereof, the lengths all differing from each other, selecting a group of the longest of the lengths and assembling them into a closed ring with abutting ends, similarly arranging a group of the longest remaining lengths and assembling them within the first group and repeating these operations until all the cut lengths have been so assembled. A strip of grain oriented magnetic material 1 is advanced by a roller 3 through a shear device 8 until the end 9 of the strip contacts a switch 10 on an adjustable stop 11. Closure of the switch 11 cuts out the drive motor 4, actuates the shear device 8 and after a suitable time lag starts a motor 14 to rotate an indexing screw 15. The motor 14 also rotates a cam disc 18 via a variable speed gear 16. As the cut length of strip falls from the shear device, the switch 10 is opened, but the motor 14 remains energized via a switch 20, which is closed by a cam follower 21 acting on the disc 18 so that when the follower falls into a notch 22 the switch 20 is opened. The apparatus produces groups of laminations wherein the increment of length increase of each is equal or, if required, one or more laminations in a group may have a greater increment of length increase. A counter 24 is set so that after a pre-determined number of laminations have been cut, a magnetic device 25 retracts the stop 11 additionally to the movement caused by the screw 15. The apparatus may be arranged to cut the longest lamination first. A group of laminations is arranged with their ends in different transverse planes and a core group is formed between walls (45), (Fig. 5, not shown). The ends of the outermost lamination overlap, and they may be welded or taped together. Other core groups may be formed and placed in succession inside the first group and the air gaps between the butt jointed laminations may be arranged in zig-zag formation (Fig. 2, not shown). The core, with a mandrel 47 inside, is placed between forming plates 48, 49, 51 and an hydraulically operated piston forms the core to its final shape prior to heat treatment. Finally, if the outer laminations have been welded, the weld is broken, or if they were taped, the tape is burned up in the furnace during heat treatment.