Patent GB-1353473-A (GB)
Title: Apparatus for and method of manufacturing laminated cores for  ignition coils
IPC: H01F3/04
Filed: 1970-11-07
Abstract: 1353473 Making magnetic cores; angular bending; corrugating; punching JOSEPH LUCAS (INDUSTRIES) Ltd 22 Oct 1971 [7 Nov 1970]- 53089/70 Headings B3A B3E and B3W [Also in Division H1] A laminated core for an ignition coil is manufactured by corrugating a metal blank comprising a plurality of parallel slits. Apparatus for use in the manufacture comprises a corrugating station 15, Fig. 2, which receives sheet metal blanks 32, Fig. 5, each of which has a plurality of parallel slits dividing the blank into a plurality of laminµ 33 interconnected at their ends 34, the station including a plurality of tools, Figs. 6-14 (not shown), which operate sequentially to corrugate the blank along the lines of the slits, the uncorrugated portion of the blank being free to move relative to the tools during the corrugation. The apparatus further includes a fixed platen (11), Fig. 1 (not shown), and a movable platen (12) of a press. A blank forming station 13 receives a continuous strip 14 of mild steel, coated with insulating varnish, and crops the strip with movable cutters 21 to form a predetermined length of strip. The cropped strip is then fed between fixed and movable parts of a slitting tool 22 which includes a plurality of punches of differing width and rectangular cross-section. As the movable platen 12 descends the punches perform a shearing action on the strip to produce a plurality of predetermined spaced slits. A planishing tool 23 is then used to flatten the slitted strip whence the strip passes to a guillotine 24 where the strip length is cut to the length of the core to be produced to form a blank 32. This blank is transferred via a reciprocal carriage 35, to the corrugating station 15 which includes three stages 45, 78, 97 each comprising sequentially-operated sets of tools and which perform substantially identical operations successively from the centre of the blank outwards. The first stage 45 comprises punches (55), (57), (59), Fig. 6, which define longitudinallyextending triangular ribs, the apices of the ribs being presented towards anvils (46), (51), (52). The central slit of the blank is aligned with the apex of punch (55) and groove (49) of anvil (46) so that upon descending of platen 12 punch (55) engages blank 32 along the centre slit and bends the blank into groove (49). The remaining four punches descend, against the action of compressed air in chamber 61, to bond the blank from the central slit outwards so that the corrugations are formed sequentially. Transfer mechanisms 74, 95 are provided between the three stages and transfer mechanism 111 transfers the completely corrugated blank to a coining station 16. Slidable in between a base (113) Fig. 16 (not shown) and cover-plate (114) are two jaw members (116) which are used for compressing the corrugated blank laterally to form an unfinished core of substantially cylindrical crosssection. A pair of strippers (128) mounted on the cover-plate ensure that the compressed core is removed from the jaw members, and a head (133) of arm 132 transfers the core to a sizing station 17 for standardization of the core diameter. This station includes an indexing disc (136) Fig. 18 (not shown) such that as platen 12 descends the disc is indexed to move the coil from a horizontal to a vertical position and then a push-rod 146 pushes the core from passage (137) into sizing die (148). After sizing the disc is indexed back through 90 degrees and the finished core is removed via a transfer tube 18 or a conveyer mechanism. All the stations of the apparatus operate simultaneously and thus a finished core is produced each complete stroke of the press. The tools of each station are independently detachable and thus serviceable. The apparatus also includes a safety system for stopping its operation should the transfer mechanism or carriage cease to function correctly and to check whether an unfinished core has been inserted into the indexing disc at the correct point of the operating cycle.