Patent ID: 6092278
Filing Date: 2000-07-25
Classification: H01F,Y10T

Abstract:
A method of making a pencil core for use with a coil for igniting spark plugs, said core having a plurality of substantially flat rectangular laminations where a width of at least one lamination at a center of the core is wider than the other laminations so that laminations above and below the at least one central lamination have decreasing widths, and wherein the laminations have a substantially same thickness and a substantially same length, comprising the steps of:feeding a flat strip of core steel into a die having a plurality of stations;punching pilot holes in the strip;registering the pilot holes with pilot registration members;providing a plurality of scrap region blanking stations each of which blank out two spaced parallel regions of a same unchanging area from the strip but with each of the scrap region blanking stations blanking out the regions at a different spacing thereby creating a series of said laminations, to be used, above and below the at least one central lamination and having decreasing widths;at a lowermost lamination of the core to be formed providing at least one pierced hole with a piercing station and at an embossing station providing at least one embossment in each of the laminations preceding the last lamination for each core to provide an embossment for interlocking the laminations together with one embossment being received within a succeeding inside surface of the embossment in the following lamination and wherein the last embossment is received in the pierced hole of the last lamination; andafter all of the scrap region blanking stations, the piercing station, and the embossing station, arranging a blanking and stacking station which first blanks laminations free from the strip at and corresponding to the parallel scrap regions of differing spacing, and for said at least one central lamination of the core blanking the strip without any associated parallel scrap regions, and as each lamination is blanked free from the strip, stacking that lamination onto previously blanked laminations so as to interlock the laminations with the embossments in unified completed cores of a substantially circular file which are held in a choking section of the blanking and stocking station which holds the cores by the widest at least one central lamination, the cores then being pushed down through the choking section and thereafter output from the die.