Patent GB-1444857-A (GB)
Title: Device for forming a peripheral groove in the open end of a hollow body
IPC: B21D51/26
Filed: 1974-11-15
Abstract: 1444857 Stamping KM-ENG AG 15 Nov 1974 [21 Nov 1973] 49588/74 Heading B3Q Apparatus for forming a groove c, Fig. 2, adjacent the flange d on a metal container comprises a reciprocal punch holder 1, Fig. 3, in which a punch 6 is mounted against a resilient member 16, a holder 17 for the container 18, outer die segments 23 slidable radially on the holder 17, at least one inner die member 32 and a hold-down 35, the die segments 23 and die member 32 being pressed from the outside and inside respectively, during a working stroke of the holder 1 to form the groove. The apparatus may be located and operated on the drawing or extruding press used for producing the initial flanged container. In a first form of the apparatus rigid external die segments 23 are closed on to the container by inclined surfaces in a surrounding ring 28. An elastomeric internal annular die 32 is expanded by a bush 33 to form the lower part of the groove-wall, and a lip 41 on the hold-down 35 coacts with the die segments 23. The die 32 is located behind the head 6b of the punch which is secured to the shank 6a by a bolt 6c. An enlargement 6d of the shank with lubrication passages is engaged by a lateral wedge 11 pressed inwards by a stack of pre-stressed elastomeric washers 16a to prestress the punch. The die-segments 23 are retained on top of the holder 17 by a ring 25 and have dovetail screws 26 engaging inclined slots 27 in the stationary ring 28. Downward movement of the holder by the hold-down 35, against one or more return springs 42, moves the die-segments 23 against the container. The punch having seated the container in the holder 17 and depressed a pneumatically-operated ejector 19b against a stop 21 so that it follows the descending holder, now remains stationary as continued movement of the punch-holder 1 and bush 33 expand the internal annular die 32. The hold-down 35 is retained by bolts 36 and pre-stressed by resilient washers 39. After raising of the formed container by the ejector 19, it is held by a magnet (50), Fig. 4 (not shown), in the head 19c of the ejector. Release of the container from the punch may be assisted by compressed air passed through the punch. Instead of pre-stressing by the wedge 11, a bell-crank may be used or a spring stack coaxial with the punch. In a different construction, Figs. 9 and 11, using rigid outer and inner die segments 69, 66, the inner segments 66 are cammed outwards indirectly by an inclined surface 64 on the punch as they are pressed down by a die projection 77 on the hold-down 35. The sixteen outer diesegments 69 are then pressed inwards as pins 78 contacted by continued movement of the punch holder, depress a bevel-closing ring 71 engaging the segments 69. Return springs 73 are provided for the ring 71 and a resilient ring 74 for the segments 69. The inner segments 66 are encircled by a rubber ring 68. Indirect contact between the punch surface 64 and the segments 66 is by wedges 65, Fig. 11. An auxiliary stripper 56 is provided on the end by the punch and an auxiliary ejector 62 on the ejector 59. In various modifications, Figs. 12-15 (not shown), action of the inner die-segments is by levers (81) and resilient members (80) or by hooks (83); two inner die-segments 66 may be operated by a pair of wedges.