Patent Publication Number: US-7896792-B2

Title: Packaging machine and method for cutting packages

Description:
FIELD OF THE INVENTION 
     The invention relates to a packaging machine and to a method for cutting packages. 
     BACKGROUND OF THE INVENTION 
     From DE 38 41 250 A1 a packaging machine according to the preamble of claim  1  is known. This packaging machine has a transverse cutting device and, arranged in succession, a longitudinal cutting device. The longitudinal cutting device cuts the packages in the longitudinal direction of a web by means of a rotating blade. This device requires regular maintenance and adjustment operations. Furthermore, the service life of the blades is limited and the quality of the cut is not sufficient for high-quality packages. The longitudinal cutting device runs continuously during the advance of the packages. 
     From DE 25 06 446 a packaging machine is known in which the separating of the packages is also performed in two steps. First, a web is cut in the transverse direction to thereafter cut out strips which are separated into single packages in a further device. Each package is separately cut off the strip and, therefore, the capacity is limited. 
     In DE 31 18 946 A1 a device for cutting out packages from a web of film is proposed in which the outline of the packages is cut in one working step. The device consists of a complicated unit comprising a press with high forces and a cutting tool which is individually adapted to the number, size and outline of the packages. The output of the packages from the device is laborious. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a packaging machine and a method for cutting packages with which packages are produced with a high quality of cut, a high output yield is achieved, and the packages are provided in an easily accessible way for the further processing. 
     The object is attained by a packaging machine according to claim  1  and by a method for cutting packages according to claim  9 . 
     The invention in particular has the advantage that taking over of the cut packages can be performed from above and with high precision. Furthermore, by dividing the working steps in respect of the first and the second cuttings, a higher flexibility in specific applications is possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will arise from the description of embodiments with reference to the enclosed figures. 
       The figures show: 
         FIG. 1  a schematic view of a packaging machine according to a first embodiment with the front cover omitted; 
         FIG. 2  a top view onto the packaging web of the packaging machine according to  FIG. 1  in the region of the transverse and the longitudinal cuttings according to a first embodiment; 
         FIG. 3  a top view onto the packaging web according to a second embodiment; 
         FIG. 4  a top view onto the packaging web according to a third embodiment; 
         FIG. 5  a top view onto a package produced with the embodiment according to  FIG. 2 ; 
         FIG. 6  a top view onto a package produced according to the embodiment according to  FIG. 3 ; and 
         FIG. 7  a section taken along line A-A of the cutting station according to  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     As can be seen in  FIG. 1 , at its input side the packaging machine comprises a roll of film with a first web of film  1  which is taken hold of by a transport device  2  on both sides and which is transported to an output side. In a forming station  3  containers  4  formed from the web of film  1  are created. As can be seen from  FIGS. 2 and 3 , several containers  4  are arranged in a row over the width of the web of film  1 . As an option, a filling station  5  is provided in which the containers  4  are filled with products  6 . In succession thereof, a supply for a second web of film  7  with which the containers  4  are covered and sealed in a sealing station  8  is located. Further, a first cutting station  9  is provided in which the web of film containing the containers is cut in a first direction on two opposing sides of the containers. In the transport direction  12  downstream of the first cutting station  9 , a second cutting station  10  is provided in which the web of film  1  is cut in a second direction on opposing sides of the containers. Behind the second cutting station  10  a transport device  11  is provided which conveys the completely separated containers coming out from the second cutting station  10  to a transfer station (not shown). The transport device  2  is formed such that it advances the web of film in a fixed-cycle way wherein the period of time in which the transport device is stationary in a working cycle at least corresponds to the time the station with the longest operating time needs for the working process. 
     In the embodiments shown in  FIGS. 1 to 3  the first cutting station  9  is formed as a transverse cutter which preferably is a punch and comprises a punch knife  13  extending transverse to the transport direction  12  and arranged below the web of film which presses the web of film  1  against an abutment arranged above the web of film and, in doing so, punches through it. Anyhow, the inverse arrangement is possible as well in which the punch knife  13  is located above the web of film and the abutment below. Further, a control is provided which operates the first cutting device  9  in accordance with the fixed-cycle advance of the transport device  2  in an intermittent fixed-cycle way such that the cutting of the web of film transverse to the transport direction  12  is performed when the transport device is stationary between to advances. 
     In a first embodiment of the geometry of the punch knife  13  which is shown in  FIGS. 2 and 5 , the punch knife  13  of the first cutting station  9  is formed such that it cuts, between the containers  4 , star-shaped cut-outs  15  with curvatures  15   a  directed to the inside which later on, as can be seen in  FIG. 5 , form rounded corners  4   c  of the cut out containers. As can be seen in the upper half of  FIG. 2 , the punch knife  13  in a first example may be formed such that line-shaped cuts  16  are created between the containers  4  transverse to the transport direction  12 . As can be seen in the lower half of  FIG. 2 , in a second example the punch knife  13  may be formed such that strip-shaped cut-outs  17  are created between the star-shaped cut-outs  15 . Further, the punch knife  13  does not extend over the whole width of the web of film  1  and, therefore, a strip  18  remains at the side edges of the web of film  1 , respectively. The strip serves for advancing the web of film. 
     As can be seen in  FIGS. 1 to 3  and  7 , the second cutting station  10  is formed as a longitudinal cutter and preferably as a punch which comprises a plurality of punch knives  14  having their cutting edges extending in the transport direction  12  and arranged below the web of film  1  pressing against an abutment  14   a  located above the web of film  1  and, in doing so, punching through the web of film. Here as well, the inverse arrangement is possible in which the punch knives  14  are located above the web of film and the abutment is below. As shown in  FIG. 5 , the distance B between the punch knives  14  is wider than the width of the cavities  4   a  of the pre-formed containers  4  having the result that, after the complete separating, a container  4  comprising a rim  4   b  and having an overall width B is created. The number of punch knives is by 1 larger than the number of containers  4  arranged side by side transverse to the transport direction  12  in a transverse row. The length of the punch knives corresponds to the length L of the container shown in  FIG. 5 . In a first embodiment of the geometry of the punch knives  14  as shown in  FIG. 2 , these are formed such that line-shaped cuts  19  are created in the transport direction  12 . The distance of the two outermost punch knives relative to each other is smaller than the width of the web of film  1  and as wide as the length of the punch knife  13  of the first cutting station, having the result that rim portions  18  which constitute waste remain after cutting. 
     Further, a control is provided which operates the second cutting station  10  in accordance with the fixed-cycle of the transport device in an intermittent fixed-cycle way such that the cutting in the transport direction is performed when the transport device is stationary between to advances and that, when the cut is effected, the punch knives and the abutment are moved away from the web of film such that an access to the containers from above is allowed for. 
     During operation, first the web of film  1  is supplied to the forming station  3  via the transport device  2  in a fixed-cycle way. The containers  4  are deep-drawn in the forming station  3 . Then, as an option the containers are filled with products  6  in a filling station  5  and closed with the upper film  7  and sealed in the sealing station  8 . The thus-connected containers are transported on in a fixed-cycle way by the transport device  2  and supplied to the first cutting station  9  which effects the cut shown in  FIG. 2  in a direction transverse to the transport direction  12  intermittently in a fixed-cycle way, while the respective transverse rows of containers in front of and behind the cutting station  9  are stationary. Since the rim portions  18  remain, the web of film  1  can further be held thereon and transported on. As soon as a transverse row of containers arrives in the second cutting station  10 , the punch knives  14  are operated there and a plurality of longitudinal cuts  19  is created which open out to the star-shaped cut-outs  15  and, in doing so, completely separate the containers  4  from each other. 
     After each step the punch knives  14  and the abutments  14   a  are moved away from the web of film such that the decollated containers are freely accessible from above while they are transported on the transport device  11 . By this, a taking-over with high precision for the further processing is allowed for since the containers have a defined distance relative to each other. 
     As shown in  FIG. 5 , the cut-out container comprises rounded corners  4   c  the curvature of which is created by the star-shaped cut-outs  15 . Between a rounded corner  4   c  and a longitudinal side  4   d  of the container, a small corner  4   e  exists which arises due to the fact that the distance of the punch knives  14  of the second cutting station  10  is not exactly adjusted to the curvature of the star-shaped portion  12  which is punched out by means of the first cutting station. The corner may be utilised as assistance for peeling off the upper film  7  during opening of the container  4  at a later date. 
     As can be seen in  FIG. 2 , the containers  4 ′,  4 ″ in the upper part are formed without cutting waste at their short sides, while the containers  4  and  4 ″′ in the lower part are formed with a cutting waste at their short sides. This results from the punching out of the strips  17  in the first cutting station. 
     In the second embodiment of the geometry of the punch knives of the second cutting station  10  as shown in  FIG. 3 , the punch knives are formed such that in between and at the end of the longitudinal sides of the respective containers  4  longitudinal strips  20  are punched out. Due to this, packages  40  as shown in  FIG. 6  are created. A package  40  differs from the package  4  shown in  FIG. 5  in that, due to the cutting out of the strips  20 , the corner  4   e  is not present and the rounded edges  40   c  step-free merge into the longitudinal sides  40   d.    
     The selection of the geometry of the punch knives is carried out depending on the packaging material and on the requirements to the quality of the cut edge of the container. 
     In a modified embodiment of the packaging machine which is schematically shown in top view in  FIG. 4 , the first cutting station  90  is formed as longitudinal cutting station in which longitudinal cuts  91  are created between the packages. The second cutting station  100  is formed as transversal cutting device in which one or more cuts transverse to the transport direction  12  are created. By the second cutting station  100  operating intermittently, here as well, a precise taking-over is possible, for example by means of a manipulation apparatus from above. 
     Modifications of the embodiments described above are possible. For example, the first cutting station  9 ,  90  not necessarily has to be formed as a punch but may also be a simple cutting by knives. The geometries of the punch knives are adapted to the requirements. The star-shaped punch-out not necessarily has to be present; if not, packages having pointed corners are created. 
     The longitudinal cutter may also be formed as a shear blade such that the longitudinal edges are cut waste-free. 
     It is also possible to deep-draw, fill, seal and cut multiple containers in a row in transport direction simultaneously. In this case, the cutting device formed as transverse cutter comprises a plurality of parallel cutting blades. 
     Further, the invention is not restricted to a packaging machine in the form of a deep-drawing machine but may also be applied in a forming machine for packaging containers.