Patent GB-926866-A (GB)
Title: Improvements relating to the manufacture of inductive circuit components
IPC: H01F27/245
Filed: 1960-11-01
Abstract: 926,866. Making laminated cores; angular bending; metal sheet feeds. D. A. PEARS (Sylvania Electric Products Inc.). Nov. 1, 1960, No. 37546/60. Classes 83 (2) and 83 (4). In a method of making an electromagnetic component having a laminated three leg C core comprising a number of nesting bent strips, strip stock is fed through a work station in separate measured lengths for each leg dimension, the amount for one outer leg differing from the amount for the other outer leg where it is bent after each but the last of the measured feeding steps and severed after the last feed to form a single lamination whereupon the stock strip is fed through in a second sequence, the measured lengths being greater by the thickness of the strip and the operations are repeated to produce the required number of nesting pieces. The laminations are of C-form with one arm longer than the other and stacked so that the long and short arms alternate to produce the core shown in Fig. 2. A core leg is inserted through a wound core. Two such cores may be assembled with a winding 30 as in Fig. 3. At the work station the strip 36 is roller fed beneath a die plate 40, Fig. 12, where it may be bent up against the face 42 of the plate by a hinged bar 44 or may be sheared by a blade 46 moving across the cutting edge 170 of an insert 172 in the plate 40. The bar 44 is mounted on a shaft 132 attached to gears 134, Fig. 13, driven from a pneumatic cylinder 146 through a rack 140 and gears 136, 136a. The degree of turn may be varied by altering the position of the cylinder. The cutter is actuated from a cylinder 188, Fig. 15, through levers 186 and a toggle 190, adjustment of the height of the cutter being made by a nut 198. During cutting the strip is clamped by a member 40 also operated from a pneumatic cylinder and having a height adjustable by a nut similar to the nut 198. The stock strip is fed by a roller assembly (not shown) driven by a shaft 50 coupled to a shaft 54, Fig. 6, which for a three-sided lamination is rotated in turn by a different amount by three separate drives. The shaft 54 may be coupled by one of three one-way clutches 56 to one of three gears 58 each in mesh with a rack 60 reciprocated from a pneumatic cylinder 226 (not shown). When a cylinder 226 pulls a rack 60 downwards it drives the shaft 54 through a gear 58 to feed the strip by an amount determined by the stroke of the rack. On the return up stroke of the rack, the gear 58 idles. The feeding stroke of a rack 60 is determined by another rack 62 which is driven from a clutch 56 by a gear 64 so that it moves from a predetermined starting position against a stop nut 66 until it strikes a stop 232 to actuate a switch S12 to stop the feed. On the idle return stroke of the rack 60, the control rack 62 is returned to the stop nut 66. The increase in the lengths of the three sides for each succeeding lamination is obtained by an adjustment of the rearward position of each of the control racks 62 after each feeding stroke of the associated rack 60. To effect this adjustment each stop nut is slidable along a track 234, Fig. 9, by means of a screw 68 which is turned in measured increments through a chain 236 and a clutch 70 from a control shaft 72 which is rocked by a pneumatic cylinder 238 through an angle determined by the setting of a stop screw 78, Fig. 10, and such that each rock turns the screw 68 and thus moves the nut 66 by an amount sufficient to increase the length of feed by the thickness of the strip material. The initial setting of the three stop nuts 66 is effected by electrically disconnecting the clutch 70 and then rotating the shaft 68 by means of a motor 80. The shafts 68 are coupled through clutches 84 to sprockets 254 driven by the motor 80 through a chain 82 and each shaft carries a disc 258 mounting an adjustable stop arm 260 engageable with a stop 264 connected to the nut and slidable so that its position can be set with reference to a scale 271 and pointer to correspond with the initial nut location. Each stop is zeroed in turn, the clutches 84 slipping until the others are zeroed and the motor is stopped by operation of a switch by a lug on the chain. Specifications 7856/1889 and 926,867 are referred to.