Abstract:
The method forms a blank into the container body. A disc-shaped blank is punched out of a metal sheet. Following the punching process, the two edges of the blank are compressed. The disc-shaped blank thus obtains a symmetrical shape. With any of its two flat sides, the blank can be transported into a forming position, from which it is then formed into the container body. The edges obtain an accurately predetermined shape and can thus be arranged more easily in the desired forming position. Preferably, both edges are machines simultaneously in response to compressing the two edges of the blank.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a method for producing a container body, which is produced from a blank, which is identified as round blank, in a seam and joint-free manner. For example, the container body encompasses a cylindrical container wall, which, at one end, merges axially into a container part, which closes the container body, such as a container bottom. The container body, which is to be produced, can thus be closed axially at one end by means of the container part, or can also encompass an opening at both ends. The container body is open at at least one axial end. Such container bodies can be produced by means of impact extrusion, for example, so as to produce tubes, cans or the like of metal, for example aluminum, or of a metal alloy. The shape of the container body can vary as a function of the design of the die and of the stamp. 
         [0002]    An extrusion press for producing such container bodies is known from DE 1 402 784 A, e.g.. Round blanks or plates are fed to the extrusion press and are positioned between the die and a stamp. This stamp presses the plate into the die. The material thereby flows opposite to the direction of motion of the stamp around the latter and thereby also flows out of the die, wherein forming takes place between the container body. As an alternative to this backward impact extrusion, forward impact extrusion methods or combined forward-backward impact extrusion methods are also known, in the case of which the material also flows exclusively or additionally, respectively, in the direction of motion of the stamp. 
         [0003]    A different method for producing a container body by means of deep drawing-ironing is described in DE 2 308 132 or DE 10 2010 000 094 A1, for example. Initially, round blanks are punched out of a sheet metal plate. In an ironing station, said round blanks are subsequently pulled through a die with the help of a drawing punch and are thereby formed. 
         [0004]    Impact extrusion methods for producing cans are known and have been used for a long time. In the case of these methods, however, it is necessary to position the punched-out disc-shaped blanks, which are also identified as round blanks, in a desired orientation upstream of the extrusion presses so as to form the container body. This is necessary, because the blanks or round blanks encompass a punching burr after the punching. On principle, this punching burr does not interfere with the production of the container body, because the edge of the container wall located opposite the container bottom is cut off in any event after forming the disc-shaped blank into the container body. Unevenness at this edge, which is formed by the punching burr, is thus unproblematic. 
         [0005]    However, this requires the orientation of the blank or of the round blank, respectively, prior to the impact extrusion such that the flat side, which encompasses the punching burr, is assigned to the axially open end of the container body, which is to be produced. In response to an incorrect orientation of the blank prior to the impact extrusion, the punching burr can lead to holes in the container wall or to so-called laminations in the wall. This is the case, if the punching burr is pressed into or through the die, respectively, opposite the flow direction of the material. This problem has been known for a long time. Today, it is solved in that a forming takes place at the same time the disc-shaped blank or round blank, respectively, is punched out in response to which the round blank is bent. This is identified as cambering. By bending the blank, the latter is formed unevenly on its two sides. This is why a sorting is possible in response to the feeding or transporting, respectively, of the blanks to the forming station, so that the blank comprising the punching burr thereof always encompasses the desired orientation in flow direction of the material. Such a sorting extensive. Errors, which in turn entail errors in response to the forming of the blank into the container body, can also occur in response to the sorting. 
         [0006]    In response to the deep drawing-ironing of round blanks into container bodies, the latter are on principle seized by means of a gripping device and are placed between the drawing stamp and the die. It can occur thereby that round blanks, which lie flat on top of one another, stick to one another and that two round blanks are grabbed inadvertently and are fed to the press. This leads to errors. 
       SUMMARY OF THE INVENTION 
       [0007]    It can thus be considered to be the object of the instant invention to provide for a method, which is less extensive and which avoids or at least significantly reduces errors in response to the forming of the blank into the container body. 
         [0008]    According to the invention, this object is solved by means of a method comprising the features of patent claim  1 . 
         [0009]    According to the invention, a disc-shaped blank, which preferably comprises a circular contour, is punched out of a metal sheet. In the case of a circular contour, the blank can also be identified as round blank. Following the punching process, the two edges of the blank are compressed. Due to this compression process, a punching burr, which might be present, is removed. The disc-shaped blank thus obtains a symmetrical shape opposite a symmetrical plane, which runs centrally between the two flat sides of the blank. By compressing the two edges and due to the resulting symmetrical design of the blank, a subsequent sorting is superfluous. With any of its two flat sides, the blank can be transported into a forming position, from which it is then formed into the container body, for example in an impact extrusion process. By compressing the two ring-shaped edges, a calibration of the blank is also attained. Irregularities of the punching process have been removed. The edges obtain an accurately predetermined shape and can thus be arranged more easily in the desired forming position, which in turn, prevents errors in response to the forming process. The transporting or feeding, respectively, of the disc-shaped blanks to the forming station is also simplified, because all blanks, except for slight process tolerances in response to the compression, encompass the same shape and because irregularities of the punching process have been removed. The blanks, which are to be transported, are flat and do not encompass an irregular punching burr. 
         [0010]    The forming the blank into the container body can also take place by means of impact extrusion, for example. In the forming position, the blank can be arranged between a stamp in the upper tool of the press and a die in the lower tool of the press. In the forming position, the blank preferably rests with one of its two flat sides against a contact surface of the forming press, which surrounds the die in a ring-shaped manner, for example. 
         [0011]    Preferably, both edges are machines simultaneously in response to compressing the two edges of the blank. A high flow and an efficient production process can be reached through this. Machines, for example, which can be used for rimming and/or coining coins, are suitable for compressing the two edges of the blank. Such machines are available on the market and can be used very easily for the method according to the invention. Even though the blank for the container body production preferably consists of aluminum, it turned out that the machines, which are used for rimming coins, are also suitable for rimming the round blanks made of aluminum, which are punched out for the container body production. Aluminum is a very soft material. It was nonetheless possible to compress the edges so as to obtain the desired shape, without negatively influencing the cylindrical, disc-shaped design of the round blank. 
         [0012]    During the compression, the peripheral surface of the blank, which is bordered by the two edges, which are to be compressed, preferably rolls off of a compression tool. The two edges are compressed and are brought into the desired shape by means of a pressure forming process. The shape of the round blank or of the blank, respectively, in the area of the edges and of the peripheral surface is predetermined by the compression tool. In the case of a preferred exemplary embodiment, a compressed groove, in which the round blank rolls off with the peripheral surface, is present in the compression tool for this purpose. 
         [0013]    By compressing the round blank, a radius, a circumferential bezel or also a circumferential border can be formed at the two edges. Such a border can serve the purpose, for example, to simplify the positioning of the round blank in the forming position. 
         [0014]    Advantageous embodiments of the method follow from the dependent patent claims as well as from the description. The description is limited to significant features of the invention as well as to other structural conditions. Preferred exemplary embodiments of the invention are explained by means of the drawing. 
     
    
     
       IN THE DRAWINGS 
         [0015]      FIG. 1  shows a strip-shaped sheet metal plate in a schematic illustration as basic material for punching out round blanks, 
           [0016]      FIG. 2  shows a schematic, block-diagrammatic illustration of the punching process, 
           [0017]      FIG. 3  shows a partially cut illustration of the border area of a round blank after being punched out, 
           [0018]      FIG. 4  shows a first exemplary arrangement for compressing the edges of the round blank in partial illustration, 
           [0019]      FIG. 5  shows a second exemplary arrangement for compressing the edge of the round blank in partial illustration, 
           [0020]      FIGS. 6 to 8  show a partially cut illustration of a respective round blank after compression comprising different edge shapes and 
           [0021]      FIGS. 9 to 11  show an exemplary, highly schematized illustration of an impact extrusion process. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The invention relates to a method for producing a container body comprising a hollow-cylindrical shape, for example, which, in the case of the preferred exemplary embodiment, is open at an axial end and which, at the other axial end, merges in a seam and joint-free manner into a container part, which closes the container body. As an alternative, a container body, which is open at both axial ends, can also be produced by means of impact extrusion. The container body is produced from a disc-shaped, cylindrical blank  10 . In the case of the instant method, the blank has a circular contour and will thus be identified hereinbelow as round blank  10 . 
         [0023]    In a first method step, the round blanks  10  are punched out of a metal sheet  11 , which, according to the example, consists of aluminum. The metal sheet  11  can be unwound from a roll as strip-shaped material and can be punched out with the help of a punching tool  12 , as it is illustrated schematically in  FIG. 2 . 
         [0024]    After the punching, the round blank  10  encompasses a punching burr  14  at one of its two flat sides  13 . This punching burr  14  is irregular and causes an asymmetrical design of the round blank  10 . 
         [0025]    After punching out the round blank  10 , a compression process is carried out to remove the punching burr  14  as well as to produce a symmetrical shape opposite a symmetrical plane S, which runs centrally between the two flat sides  13 . The two ring-shaped edges  15 , which border the peripheral surface  16  of the round blank  10 , are compressed thereby and are brought into a desired shape. Different exemplary embodiments of the round blanks  10  are illustrated in  FIGS. 6 to 8 , wherein each round blank  10  encompasses a different edge shape. Due to the compression, a radius R, a bezel F or a circumferential projection can be formed at an edge  15  for forming a border V. In the case of the exemplary embodiment illustrated in  FIG. 6 , the projection or border V, respectively, encompasses a rounded shape and is closed in a ring-shaped manner. It projects beyond the respective adjoining flat side  13  and merges continuously into the peripheral surface  16 . The compressed edge  15  of the round blank  10  can merge into the peripheral surface  16  and/or the assigned flat side  13  either rounded or so as to be bordered by edges. However, the edge  15  does not project beyond the cylinder jacket surface defined by the peripheral surface  16  in any of the exemplary embodiments. 
         [0026]      FIGS. 4 and 5  illustrate compression devices  17  for compressing the two edges  15  of the round blank  10  in a schematic manner. The compression device  17  encompasses a compression tool  18  comprising a compressed groove  19 . The compressed groove  19  runs along a segment of a circle. Accordingly, the compression tool  18  can encompass a ring segment-like contour. At a distance to the compression tool  18  and to the compressed groove  19 , a drive wheel  20  comprising a drive groove  21  is arranged coaxially to the compressed groove  19 . For compression purposes, the round blank  10  is accommodated in the drive groove  21  of the drive wheel  20  and is rolled off along the compressed groove  19  of the compression tool  18 . To compress the entire edge  15 , the length of the compressed groove  19  corresponds at least to the periphery of the two edges  15  of the round blank  10 . The cross sectional shape of the compressed groove  19  determines the shape of the edge  15  after the compression process. In response to the compression, the round blank  10  is clamped between the drive wheel  20  and the stationary compression tool  18 , whereby the two edges  15  form in the compressed groove  19  and adapt to the shape of the compressed groove  19 . 
         [0027]    The two exemplary embodiments of the compression devices  17  in  FIGS. 4 and 5  operate according to the same principle. In both cases, the drive groove  21  and the compressed groove  19  are arranged coaxially to the drive axle of the drive wheel  20 . In the case of the exemplary embodiment according to  FIG. 1 , the radius of the compressed groove  19  is larger than the radius of the drive groove  21 . In the case of this first exemplary embodiment, the compressed groove  19  encompasses a larger distance to the drive axle of the drive wheel  20 , than the drive grove  21 . In contrast, the drive groove  21  and the compressed groove  19  are arranged at an axial distance to one another and have the same distance to the drive axle in the case of the second exemplary embodiment according to  FIG. 5 . 
         [0028]    Further modifications of the exemplary embodiments of the compression device  17  are possible. For example, as a modification of the first exemplary embodiment according to  FIG. 4 , the compression tool  19  could be arranged within the drive wheel  20 , so that the distance of the compressed groove  19  to the drive axle is smaller than the distance of the dive groove  21 . In the case of all of the exemplary embodiments, the compressed groove  19  and the drive groove  21  are oriented so as to be aligned with one another, so that the round blank  10  engages with the compressed groove  19  as well as with the drive groove  21  and can roll off in both groves  19 ,  21 . 
         [0029]    After compression, the round blanks  10  are finally transported to a forming device  22 , which is shown in  FIGS. 9 to 11  in a schematic and highly simplified manner. For forming purposes, the round blanks  10  are positioned in a forming position P in a die  23  of the forming device  22 . The forming device  22  further includes a stamp  24 , which can be moved along its longitudinal stamp axis relative to the die  23 . At a distance to the die  23 , provision is made for a wiping device  25 , which encompasses an opening  26 , through which the stamp  24  projects. In the area of the opening, the wiping device  25  can rest against the stamp  24  or can form a small gap to the jacket surface of the stamp  24 , which is smaller than the wall thickness of a container body  27  formed from the round blank  10 . 
         [0030]    A forming device  22  for carrying out a backward impact extrusion process is illustrated by means of  FIGS. 9 to 11  in an exemplary manner. As a modification, the method according to the invention can also be used for forming devices  22 , which carry out a forward impact extrusion process or a combination of backward and forward impact extrusion process. 
         [0031]    On the side facing the stamp  24 , the die  23  is open for carrying out the backward impact extrusion method as is illustrated schematically in  FIGS. 9 to 11 . After inserting the round blank  10  into the recess of the die  23 , the stamp  24  is moved towards the die  23 . After resting against the round blank  10 , the round blank is pressed between the die  23  and the stamp  24 , whereby the material initially deforms between the stamp  24  and the die  23  and thereby flows out of the die  23  along the outer stamp surface opposite the direction of motion of the stamp  24 , as is illustrated in  FIG. 10 . 
         [0032]    After the forming process has ended, the stamp  24  is moved back away from the die  23 . In response to this backward movement, it wipes the container body  27 , which was produced, on the wiping device  25 . The container body  27  is then removed from the forming device  22  and a new round blank  20  is inserted into the die  23 . The backward impact extrusion method for producing the container body  27  then starts anew. 
         [0033]    The invention relates to a method for producing a container body. A disc-shaped round blank  10  comprising a circular cylindrical contour is first punched out of a metal sheet, in particular an aluminum sheet. The two circular edges  15  of the round blank  10  are then formed into a predetermined desired shape in a compression process. During said compression process, the peripheral surface  16  of the round blank  10  bordered by the two edges  15  rolls off in a compressed groove  19  of a compression tool  18 , said compressed groove determining the edge shape. This produces a symmetrical shape opposite a symmetrical plane S, which runs centrally between the two flat sides of the round blank  10 . The round blank  10  can therefore be fed to a forming device  22  without the need for sorting and orientation. The round blank  10  can thereby be turned towards a stamp  23  or a forming die  24 , respectively, with any one of its two flat sides  13 . It is thereby possible for the round blank  10  to be fed in two different positions into the forming position P of the forming device  22  without the forming process or the container body being negatively influenced as a result. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
           10  blank, round blank 
           11  metal sheet 
           12  punching tool 
           13  flat side of the round blank 
           14  punching burr 
           15  edge of the round blank 
           16  peripheral surface 
           17  compression device 
           18  compression tool 
           19  compressed groove 
           20  drive wheel 
           21  drive groove 
           22  forming device 
           23  die 
           24  stamp 
           25  wiping device 
           26  opening 
           27  container body 
         P forming position 
       
     
         [0053]    The above detailed description of the present invention is given for explanatory purposes. It will be apparent to those skilled in the art that numerous changes and modifications can be made without departing from the scope of the invention. Accordingly, the whole of the foregoing description is to be construed in an illustrative and not a limitative sense, the scope of the invention being defined solely by the appended claims.