GB829049A - Improvements in method for forming slip rings - Google Patents

Abstract

829,049. Making slip-rings; forging; stamping. NIPPERT ELECTRIC PRODUCTS CO. Dec. 23,1957, No. 39918/57. Classes 83 (2) and 83 (4). [Also in Group XXXV] In the manufacture of an electrical slip-ring, 25, Fig. 14, sheet-metal stock is formed into a cup-shaped blank 25, Fig. 1, having a rounded circumferential edge 32, Fig. 7 (not shown), and the blank is then subjected to coining pressure concentrated on a selected portion of the blank to cause the wall metal to flow and transform the rounded edge into a square edge. Sheetmetal stock is fed through a slot 15 in a bottom die 13, Fig. 1, is sheared-off into a circular blank, Fig. 6 (not shown), by an upper die 20 and is then cupped over a lower protrusion 26. During the upstroke of the upper die, the blank is removed by an ejector 30. The blank with its rounded edge is then coined between lower and upper dies 43, 46, Fig. 3, whilst confined by a surrounding die 42. The upper and lower dies have annular ribs 53, 57, Fig. 4 (not shown), whereby the wall metal flows into a sharp corner, Fig. 9 (not shown). An ejector 62 removes the blank from the die 42. The cupped blank is then placed over a bottom die 72, Fig. 5, and a slug 76 is punched out by a punch 7 1. Simultaneously a protrusion 85 is formed on the inside surface of the bottom of the blank and a depression 78, Fig. 10 (not shown), is formed on the corresponding outer surface. The blank is removed from the punch by a stripper plate 90. A hole 79, Fig. 14, is then drilled through the depression and protrusion for reception of a wire 80 then is crimped thereto by deforming the metal at 81. Two slip-rings 25 are then assembled on a core 82 and insulated sleeve 83.