Patent GB-947342-A (GB)
Title: Die set for making metal foil lids
IPC: B21D51/44
Filed: 1961-07-10
Abstract: 947,342. Shaping metal foil lids. REYNOLDS METALS CO. July 10, 1961 [July 11, 1960], No. 24908/61. Heading B6J. A metal foil lid 20, Fig. 2, for a plastic cup 10 is shaped by means of the die set shown in Figs. 3 and 7, which comprises upper and lower die assemblies 36, 37. The upper assembly is reciprocated towards and away from the lower assembly and the two assemblies co-operate to cut out a circular blank from a sheet of aluminium foil 32 and form it to the desired shape. The assembly 36 comprises a block 38 on which is fixed a female punch 40 comprising on its working face a peripheral ridge 50 enclosing a recess 51. The base of the recess 51 is formed by the front face of an ejector 43 carried by a rod 47 slidably mounted in the block 38 and punch 40, the front face thereof having ridges 63, which help to emboss a pattern 22 in the finished lid, and a central recess 54. A gripping ring 60, having an end face lying in the same plane as the end face of the ridge 50 is fixedly mounted on the block 38 concentrically with the punch 40. In an annular space between the punch 40 and the ring 60 a pressure ring 70 is slidably mounted having an annular shoulder 78 thereon which is urged into abutment with an annular shoulder 58 on the punch 40 by spring-urged plungers 72. A stripper plate 90 is mounted on the block 38 by means of plungers 91 slidable in bores in the block and is biased towards the position shown by springs 95. The assembly 37 has a stationary bed consisting of two blocks 100, 101 fixed to a third block 102, the block 101 being within a bore 103 in the block 100. A male forming punch 110 is slidably mounted by means of a stem 117 in the block 101 and is restrained against rotation therein by a pin 119 carried by the punch and slidable in a bore in the block. The punch 110 is urged upwards by spring -biased plungers 123, and carries on its upper face recesses 112a and a conical pin 113 registering with the ridges 53 and recess 54 respectively. A second gripping ring 130 is mounted concentrically with the punch 110 and is biased upwards by spring- urged plungers 132. A second pressure ring 140 is mounted in an annular space between the ring 130 and the punch 110 and is formed on its outer surface with a shoulder 141 which engages a shoulder 138 on the gripping ring 130 and on its inner surface with a shoulder 143 which engages a flange 115 on the punch 110. The upper ends of the rings 130, 140 lie in the same plane as the upper end face of the block 100 on which the sheet of foil 32 is rested when the die set is in its open position, Fig. 3. As the assembly 37 moves downwards the stripper plate 90 first engages the foil 32. The outer edge of the gripping ring 60 then co-operates with the inner edge of the block 100 to cut out a circular blank from the foil which is subsequently gripped between the gripping rings 60, 130 and carried downwards against the spring bias of the latter ring, the pressure ring 140 falling with the ring 130. Simultaneously with the downward movement of the blank the central part thereof is shaped and embossed between the male and female punches 110, 40, a small hole being punched in the centre by the pin 113. When this has been done the downward movement of the pressure ring 140 is arrested by the abutment of its lower end with the upper face of the block 101. The peripheral portion of the blank is now held between the pressure rings 70, 140 and as the assembly 36 continues its downward movement the pressure rings remain stationary so that the peripheral portion of the blank is folded up against the outer surface of the female punch 40. The co-operating ends of the rings 70, 140 are shaped as shown in Fig. 7, 70 having an annular recess 81 of semi-circular section and 140 having an annular surface 144b, 144c of ogeeshaped section. The recess 81 forms a knifeedge portion 82 on the ring 70 which, when the die set is fully closed lies above the upturned peripheral portion of the blank. As the die set begins to open the ring 70 moves downwards under its spring bias, and its knife edge 82 scrapes the edge of the blank off the outside wall of the punch 40 and directs it into the recess 81 which in co-operation with the surface 144b on the ring 140 forms it into an annular bead 28 of substantially circular section. When the assemblies 36, 37 have moved clear of each other the lid is ejected from the female punch by the ejector 43 and is removed from between the assemblies by a blast of air. Specification 947,341 is referred to.