MACHINE FOR FORMING OUTER RINGS FOR BIMETALLIC COINS OR MEDALS, FROM ROUND METAL BLANKS

Abstract: This invention relates to a machine for forming, from round metal blanks, rings with a compressed and toothed inner edge with which to form an outer rim on bimetallic coins or medals. The machine comprises a first punching station in which the round blank is perforated by means of a suitable unit comprising a punch, die and backing die, and a second precoining station in which the inner edge is formed on the perforated round blank by compressing and toothing it by means of a further suitable unit comprising a punch, die and backing die. The pieces to be worked in the stations are fed automatically.

Description: This invention relates to a machine for forming rings to constitute an outer rim on bimetallic coins or medals, starting from round metal blanks. There currently exists a bimetallic coin constituted by an outer steel ring and an inner disc composed of a bronze, cupronickel and aluminium alloy. This coin is formed in two stages, namely a first stage in which a round metal blank is used to form the outer ring, which is worked in such a manner as to comprise a compressed and toothed inner annular edge and having its radial cross-section tapering inwards, and a second actual coining stage in which the disc is placed inside the ring and, on being struck by the coining die, expands so that its outer annular edge copenetrates the toothed inner annular edge of the ring, so that these two parts of the coin become securely joined to each other. In forming the outer ring, the first stage is carried out by a machine which in a single operation simultaneously both punches out the central portion of the round blank and for the said compressed and toothed inner edge. For this purpose, use is made of a fixed lower support carrying a die and a mobile upper support carrying a backing die and punch. The backing die has an axial hole which slidably receives the punch. The die correspondingly comprises an axial hole designed to receive the punch during the punching and formation of the inner edge of the ring. The die and backing die each comprise, at one mouth of the respective hole, a surface in the shape of a circular rim which is designed to come into contact with the round blank. This surface comprises a projecting annular lip which in practice is a continuation of the walls of the hole. The walls of each hole also comprise an equal series of longitudinal projecting ribs which terminate at the lip, and the outer cylindrical surface of the punch comprises a corresponding series of longitudinal hollow grooves. When in operation, the round blank is rested on the circular rimshaped surface of the die. The upper support is then made to descend onto the lower support so that the die and backing die lock the round blank between them, the punch passes through the central portion of the round blank so punching it out, and finally an abutment element rigid with the punch presses the die and backing die against each other. The central hole is formed in the ring during the punching operation, while the subsequent compression results in the formation of the compressed and toothed edge of the ring by the action of the lips and grooves. Bowever, the aforesaid machine has serious drawbacks. The round blank is fed and positioned on the die manually, requiring considerable accuracy on the part of the operator who has to centre the round blank on the die in order to obtain a ring with a centered hole. This restricts the machine productivity. The use of the die both as the punching element and as the element for forming the inner edge of the ring cannot be reconciled. This is becanse the punching operation causes considerable shear and compression stresses to arise in the die in a position corresponding with the lip and the terminal portion of tne ribbing which makes contact with the lip. After a certain number of punching and forming blows, the said portion fractures and requires replacement of the die. Even the use of extremely hard materials for forking the die does not obviate these drawbacks. The shape of the die and backing die does not lend to automatic extraction of the formed ring, which in many cases retains adhering to said elements. This requires manual intervention by suitable pincers, creating serious safety problems besides slowing down the production rate. From the aforesaid, it is apparent that one operator is required for each die/backing-die/punch unit for loading the round blank and unloading the ring obtained. A high production rate of finished pieces will therefore result in a high and unacceptable personnel cost. There is also a problem regarding the scrap from such working. The scrap is constituted by a disc punched from the round blank and comprising notches formed by the ribbing on the die, The presence of the notches means that the scrap cannot be used directly for forming a normal small metal coin. The scrap can therefore only be melted down. The object of the present invention is to provide a machine with characteristics such as to obviate the aforesaid problems of the current machines. This object is attained by a machine for forming outer rings for bimetallic coins or medals from round metal blanks, each ring having a compressed and toothed inner edge, the machine comprising punching and precoining tools, and being characterised by comprising: - a first working station including at least one unit formed from a first punch, a corresponding first die with a cavity arranged to receive said first punch, a first blank-holding backing die slidably mounted over said first punch, and a retainer, mounted over said first punch, for centering the round blank on the first die; ; - a second working station including at least one unit formed from a second punch with a pointed end and provided on its outer surface with longitudinal grooves, a second die with a cavity arranged to receive said second punch and provided with corresponding longitudinal ribs, said second die having a mouth of its cavity provided with an internal projecting lip, and a second backing die identical to said second die and mounted over said second punch with its mouth facing the mouth of said second die; - means for feeding the round blanks to said first working station between said first punch and said first die, and means for feeding the pieces worked in said first station to said second station between said second punch and said second die; ; - means for compressing said first backing die against said first die and means for operating said first punch to cause it to penetrate into said first die in order to perforate the round blank, means for operating said second punch to cause it to penetrate into said second die and means for compressing said second backing die against said second die in order to form the compressed and toothed inner edge on the perforated round blank. The characteristics and advantages of the present invention will be apparent from the non-limiting description of one embodiment thereof given hereafter and illustrated on the accompanying drawings in which: Figure 1 is an overall diagrammatic view of a machine according to the invention; Figure 2 is a detailed horizontal section on the line Il-II through the machine of Figure 1; Figure 3 is a detai3ed horizontal section on the line Ill-Ill through the machine of Figure 1; Figure 4 is a section on the line IV-IV through a detail of Figure 2; Figure 5 Ss a detailed vertical section on the line V-V of Figure 2, through a first working station of the machine of Figure 1; ; Figure 6 is a vertical section on the line VI-VI of Figure 2, through the first working station of Figure 5 in a particular operating position; Figure 7 is a detailed vertical section on the line Vil-Vil of Figure 2, through a second working station of the machine of Figure 1; Figure 8 shows the second station of Figure 7 in a particular operating position; Figure 9 shows a highly enlarged detail of the sectional view of Figure 8; Figure 10 is a section on the line X-X through the detail of Figure 9; Figure 11 is a detailed vertical section on the line XI-XI of the machine of Figure 1; Figure 12 is a highly enlarged plan view of a ring formed by the machine of Figure 1; Figure 13 is a section on the line XIII-XIII through the ring of Figure 12. The machine according to the invention illustrated in Figure 1 is substantially composed of a feed and advancement unit for the round metal blank, and a punching and precoining unit which actually works the round metal blank carried by the feed and advancement unit until an outer ring for a bimetallic coin or medal is obtained. Hereinafter, the reference numeral 10 indicates the round metal blank to be worked and 100 the outer ring obtained. The feed and advancement unit comprises a chute 11 fed continuously with round metal blanks 10. The chute 11 terminates over a cylindrical container 12 in which the blanks 10 arriving from the chute 11 become piled one on the other. The container 12 is open at its base to allow the entry of a slider 13 mobile with reciprocating horizontal rectilinear motion, and the exit of an individual metal blank 10. During its outward stroke the slider 13 enters the container 12 and urges the most lover blank 10 of the pile out of the container 12. During its return stroke the slider 13 leaves the container 12 to cause the overlying pile of blanks 10 to fall and a new blank 10 to come into alignment with the outlet of the container 12. The slider 13 pushes the blanks 10 one by one, as seen, along a guide 14 disposed in a position corresponding with the punches and precoining unit, as described hereinafter. At the ena of the guide 14 there is provided a second chute 15 by means of which the produced outer rings 100 are conveyed away from the machine. The punching and precoining unit has a basic structure analogoug to that of a vertical press. It comprises a punching station 16 and a precoining station 17. In particular, a base 18 is provided on which a lower support 19 is rigidly fixed. The support 19 carries a die 20 of the punching station 15 and a die 21 of the precoining station 17. Upperly, there is provided a slide 22 to which a support 23 is rigidly fixed. In a position correspondirg with the die 20, the support 23 carries an assenbly consisting of a punch, blankholding backing die and centering element, this ass5ly#bing indicated overall by 24 and forming part of the punching station 16. In a position corresponding with the die 21, the support 23 also carries a punch/backing-die assembly indicated overall by 25 and forming part of the precoining station 17. The slide 22 is driven with vertical reciprocating rectilinear motion by a crank cam, not shown because of known type, by way of a connecting rod 26. The crank cam is also used for providing the horizontal reciprocating rectilinear motion to the slider 13, as indicated diagrammatically by dashed and dotted lines, so as to synclironise the movement of the punching and precoining unit with the movement of the slider 13. The guide 14 runs between the upper assemblies 24 and 25 and the lower dies 20 and 21. Figures 2 to 11 show structural and operational details of the machine of Figure 1 which has been described briefly heretofore. With reference to Figure 2, 4, 5, 7 it can be seen that the guide lh is substantially constituted by a composite plate 27 of a certain thickness, within which there is provided a longitudinal channel 25 in which the round blanks 10 to be worked are contained and slide in. a row. The plate 27 also comprises longitudinal through slots 29 which open into the channel 28 to allow visual checking of the advancement of the blanks 10. In positions corresponding with the die 20 and assembly 24, the plate 27 comprises a lower hole 30 and an upper hole 31 coaxial with the hole 30, these opening into the channel 28. Likewise, in positions corresponding with the die 21 and assembly 25, the plate 27 comprises a lower hole 32 and an upper hole 33 coaxial with the hole 32, these opening into the channel 28. Along the channel 28 there operates a series of pairs of opposing transverse elastic pushers 34. Each elastic pusher 34 is composed of an element 35 slidably housed in a transverse seat 36 of the plate 27, which at one end rotatably carries a wheel 37 and at its other end is urged by a spring 38. The spring 38 main talus the element 35 in a position in which the wheel 37 carried by it projects into the channel 28. The functions of these elastic pushers 34 are described hereinafter. with reference to Figures 2, 3, 5, 7, it can be seen that the mobile upper support 23 is guided in its movement by four vertical columns 39 fixed to the support 23 and slidably housed in corresponding bushes 40 inserted into the fixed lower support 19. With regard to the punching station 16 (Figure 5), the die 20 is mounted on a block 41 fixed to the fixed lower support 19. The die 20 is of substantially cylindrical shape and comprises a circular axial through cavity 42 and a tapered upper mouth 43 with its edge in the form of a flat ring. The mouth 43 is housed in the lower bole 30 of the plate 27. The assembly 24 comprises, aligned with the cavity 42 of the die 20, a cylindrical punch 44 which has its working end flat and is fixed at its other end to a base 45 rigid with the support 23. The assembly 24 also comprises a blank-holding backing die 46 with a cylindrical through cavity 47, in which the punch 44 is slidably housed, and a mouth 48 with its edge in the form of a flat ring which mates with and faces the mouth 43 of the die 20. The backing die 46 is fixed to a plate 49 which is slidably mounted on a pair of columns 3 and suspended from the support 23 by tie rods 50 and tie rods 51. Over each tie rod 51 there is mounted a shock absorber block 52 which is interposed between the plate 49 and support 23. Finally, the assembly 24 comprises a centering retainer 53 constituted by a ring 54 which is kept elastically resting on an inner portion of the backing die 46 by springs 55 acting on the base 45, and to which there are annularly fixed four claws 56 which extend parallel to the punch 44 and external to it towards the plate 27, to pass through the backing die 46. In the plate 27 there are provided four corresponding cavities 57 (Figure 2) which open into the channel 28 and are designed to receive the terminal portions of the claws 56. With regard to the precoining station 17 (Figure 7), the die 21 is mounted on a block 58 fixed to the fixed lower support 19. The die 21 is of substantially cylindrical shape and comprises an axial circular through cavity 59 and a tapered upper mouth 60. The mouth 60 has an edge in the form of a flat ring with an internal projecting lip 61 (well visible in the enlargement of Figure 9). In addition, the mouth 60 comprises longitudinal ribs 62 on its inner annular wall. The mouth 60 is housed in the lower hole 32 of the plate 27. The assembly 25 comprises, aligned with the cavity 59 of the die 21, a cylindrical punch 63 which is pointed at one end and is fixed at its other end to a base 64 rigid with the support 23. The cylindrical outer surface of the punch 63 comprises longitudinal grooves 65 in positions exactly corresponding with the ribs 62 of the die 21. The assembly 25 also comprises a backing die identical to the die 21, and which is therefore indicated overall and in its component parts by the same reference numerals as the die 21 followed by the letter A. The cylindrical cavity 59A of the backing die 21A slidably houses the punch 63. The backing die 21A is mounted in a block 6raj, which itself is filed to a plate 67. The plate 67 is mounted slidablc on a pair of colmmnr 39t different from the pair on which the plate 49 is mounted. The plate 67 is also supported by the support 23 by means of respective tie rods 68 and 69. On each tie rod 69 there is likewise mounted a shock absorber block 70, which is interposed between the plate 67 and support 23. The plate 27 is elastically suspended with respect to the blocks 41 and 58 of the dies 20 and 21 respectively (Figure 5). This is obtained by supporting the plate 27 by a plate 71 which is slidably mounted on the columns 39 and rests on springs 72 acting on the support 19. Each spring 72 cooperates with a tie rod 73 which retains the plate 71 by opposing the elastic thrust of the spring. Finally, stop elements 74 are provided (Figure 11), each untied on the fixed lower support 19 by means of a tie rod 75, and with a shock absorber block 76 therebetween. The stop elements 74 are disposed in positions corresponding with the plate 67 in order to brake and halt its downward path of travel. The operation of the machine is explained hereinafter. By action of the slider 13, each round blank 10 passes stepwise along the guide 28 until it reaches a position corresponding with the die 20 and assembly 24 of the punching station 16. At this poInt (Figures 5, 6) the support 23 is lowered towards the support 19, and the following operations occur in sequence: the claws 56 penetrate into the respective cavities 57 to centre the blank 10 relative to the punch 44 and cavity 42, the mouth 48 of the backing die 46 presses the blank 10 against the mouth 43 of the die 20, so locking the blank, the punch 44 penetrates the blank 10 to remove a central portion therefrom, thus obtaining a semifinished product of ring shape indicated hereinafter by lOS. The scrap disc, indicated by lOT (Figures 1, 6), falls through the cavity 42 of the die 20 and passages 77 and 78 provided in the block 41 and support 19 respectively, and into a collection container 79. The support 23 and with it the assembly 24 then rise from the plate 27, and the semifinished product lOS continues on its stepwise path towards the precoining station 17. During the described punching stage, when the backing die 46 presses against the blank 10, the plate 27 and support plate 71 descend until the blank 10 rests on the mouth 43 of the die 20. when the backing die 46 rises from the semifinished product 105 obtained, the plate 27 and plate 71 return to their initial position by the action of the springs 72, to remove the semifinished product 105 from the mouth 43 of the die 20. When the semifinished product '105 arrives in a position corresponding with the die 21 and assembly 25, the support 23 descends towards the support 19, and the following operations occur in sequence (Figures 7, 8, 9, 10): the punch enters the hole in the semifinished product 105 to centre it relative to the die 21 and backing die 21A, the backing die 21A rests on the semifinished product 105, and the base 64 presses against the plate 67 80 as to clamp the semifinished product between the mouths 60 and 60A of the die 21 and backing die 21A, to suitably srecoin it as stated hereinafter. The support 23 with the assembly 25 then rises, and the piece worked in this manner (ring 100) advances stepwise towards the chute 15. The plate 27 also obviously descends during this precoining stage, and is returned elastically to its initial positson so as to separate the worked piece (ring 100) from the die 21. In practice, in this precoining stage an inner compressed and toothed edge is formed in the senlfinlshed product lOS by virtue of the action of the lips 61 and 61A of the mouths 60 and 60A of the dies 21 and 21A, which shape the edge, combined with the action of the ribs 62 and 62A and the grooves 65 of the punch 63, which shape the teeth as shown in the highly enlarged views of Figures 9, 10. The result is the ring 100 of Figures 12 and 13, in which the edge is indicated by 101 and the teeth by 102. A bimetallic coin or aedal is then formed with the ring 100 by means of a separate proper coining operation, as explained in the intro duction. Returning to the machine according to the invention, it is apparent that as the assemblies 24 and 25 are connected to the same slide 22, when the station 16 punches a semifinished product 105 from a blank 10, the station 17 simultaneously precoins a ring 100 from a sectifiniehed product lOS which has already passed from the station 16. The length of the channel 28 of the guide 14 and the stroke of the slider 16 first be such as to ensure, at each step, the correct positioning of a blank 10 at the die 20. and assembly 24, and the correct positioning of a senifinished product 105 at the die 21 and assembly 25. The elastic pushers 34 contribute to the correct advancement and positioning of the pieces (blanks 10, senifinished products lOS, rings 100) mutually disposed in a line, by virtue of the fact that they keep them elastically pressed against each other as can be seen from Figure 2. The machine as described and illustrated enables all the drawbacks of the known art mentioned in the introduction to be obviated. The feeding of the blanks to be worked is completely automatic. The separation of the punching and precoining operations into two stations considerably prolongs the life of the dies and backing dies. In particular, the die and backing die of the precoining station, which are extremely delicate due to the presence of lips and ribs, do not have to withstand the punching stress. This separation of the punching and precoining operations facilitates the removal of the senifinished or finished piece from the dies and backing dies, in particular in the precoining station where no forces exist which would cause the semifinished product to adhere to the die or backing die. Removal is also facilitated in the illustrated embodiment by the shape of the channel 28 which retains the piece, and by the oscillatory movement of the guide which, as seen, rises when the punching and precoining operations are finished, to remove the piece from the die. Moreover, the working scrap is constituted by discs lOT which can be immediately reused, for example for coining small single-metal coins or medals. Modifications andfor additions can be glade to the present embodiment, which is given by way of example. The various described working components can be replaced by equivalent components. For example, the feed unit which in this example is formed with a to-and-fro slider and relative guide can be replaced by mechanical hands which continuously convey the workpieces to the station. In the embodiment described heretofore and illustrated by way of example, the punching station and precoining station each comprise only one die-punch unit (die 20 - assembly 24 for the punching station 16 and die 21 - assembly 25 for the precoining station 17). A machine would be conceivable with a punching station and precoining station each comprising several die-pun#h units in parallel, served by respective parallel feeders.

Claims: CLAIMS 1. A machine for forming outer rings for bin,etallic coins or medals from round metal blanks, each ring having a compressed and toothed inner edge, the machine comprising punching and precoining tools, and being characterised by comprising: - a first working station including at least one unit formed form a first punch, a corresponding first die with a cavity arranged to receive said first punch, a first blank-holding backing die slidably mounted over said first punch, and a retainer, mounted over said first punch, for centering the round blank on the first die; ; - a second working station including at least one unit formed from a second punch with a pointed end and provided on its outer surface with longitudinal grooves, a second die with a cavity arranged to receive said second punch and provided with corresponding longitudinal ribs, said second die having a mouth of its cavity provided with an internal projecting lip, and a second backing die identical to said second die and mounted over said second punch with its mouth facing the mouth of said second die; - means for feeding the round blanks to said first working station between said first punch and said first die, and means for feeding the pieces worked in said first station to said second station between said second punch and said second die; ; - means for compressing said first backing die against said first die and means for operating said first punch to cause it to penetrate into said first die in order to perforate the round blank, means for operating said second punch to cause it to penetrate into said second die, and means for compressing said second backing die against said second die in order to form the compressed and toothed inner edge on the perforated round blank. 2. A machine as clained in claim 1, characterised in that said means for feeding the round blanks to said first working station and said means for feeding the pieces worked in said first station to said second working station comprise a single guide in which the round blanks and subsequently the worked pieces are contained and slide in a row, said guide running between said first punch and said first die and between said second punch and said second die. 3. A machine as claimed in claim 2, characterised in that said guide is suspended elastically with respect to said first and second die. 4. A machine as claimed in claim 2, characterised in that said guide is formed from a plate in which there is provided a longitudinal channel in which the round blanks and worked pieces are contained and slide, said longitudinal channel opening in a position corresponding with said first punch carrying said first blank-holding backing die and with said first die, and in a position corresponding with said second punch carrying said second backing die and with said second die. 5. A machine as claimed in claim 4, characterised in that pairs of elastically retractable transverse pushers project into said longitudinal channel, each pusher being provided with a head formed from a freely rotatable wheel arranged to enter into elastic contact with the outer edge of the round blank or worked piece. 6. A machine as claimed in claim 2, characterised in that said guide is fed with round blanks by reans of a device for the stepwise advancerent of the blanks. 7. A machine as claimed in claim 6, characterised in that said stepwise advancement device comprises a reciprocatingly mobile slider acting on a pile of round blanks, during its outward movement said slider urging the bottom blank of said pile into said guide, and during its return movement said slider withdrawing from said pile. 8. A machine as claimed in claim 1, characterised in that said means for operating said first punch to cause it to penetrate into said first die and said means for operating said second punch to cause it to penetrate into said second die comprise a press mechanism with a reciprocatingly mobile slide supporting said first and second punch, and a fixed bed supporting said first and second die. 9. A machine as claimed in claim 1, characterised in that said means for compressing said first backing die against said die comprise a base of said first punch, said base being arranged to come into contact with said first backing die in advance of the penetration of said first punch into said first die. 10. A machine as claimed in claim 1, characterised in that said means for compressing said second backing die against said second die comprise a base of said second punch, said base being arranged to come into contact with said second backing die in advance of the penetration of said second punch into said second die. 11. A machine as claimed in claim 1, characterised in that said retainer for centering the round blank on the first die comprises assembly of parallel claws arranged to come into contact with the outer edge of the blank in advance of the establish3,ent of contact between said first backing die and said first die, and to contain the blank between them in 8 position centered with respect to the mouth of the cavity of said first die.

Inventors: VITA FINZI ZALMAN, EMILIO
Applicants: DELTASIDER S.P.A.
Application year: 1985
Main classification: B21D53
IPC codes: B44B5, B21D53