Abstract:
The invention relates to a packaging machine including a sealing device, said sealing device comprising at least a first and an individually controllable second sealing tool for producing a first and a second seal uniting a lower web with a top web.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority to German Application Number 102012006696.1 filed Mar. 30, 2012, to Dieter Holzem and Christian Geble entitled “Packaging Machine With Sealing Device,” currently pending, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a packaging machine. 
     BACKGROUND OF THE INVENTION 
     Machines comprising a sealing station so as to produce packages after the fashion of  FIG. 5  are known from the applicant. The requirements to be fulfilled by such a package comprise, on the one hand, a circumferentially extending sealed seam for hermetically sealing the interior of the package, which contains a foodstuff under vacuum or in a modified atmosphere, by sealing a cover film onto a shaped bottom film/foil. This circumferentially extending sealed seam includes a cover film that can be detached from the bottom film for the purpose of opening the package. On the other hand, an additional area outside this sealed seam is sealed in the form of a planar seal so as to provide a stable area for suspending the package. This planar seal is sealed inseparably. The planar seal can be produced by applying a pressure that is higher or lower than that used for the sealed seam. To this end, a mechanical adjustment is provided, which has to be adapted to the various combinations of films. The increased or reduced sealing pressure or a change in the sealing pressure of the planar seal must not affect the sealing pressure of the sealed seam. The mechanical adjustment is carried out by changing the amount to which the sealing surface of the sealing plate of the planar seal projects beyond or falls short of the sealed seam and is very complicated and difficult to set. The amount to which the sealing surface projects is adjusted, for example, by means of packing plates of different thicknesses. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a packaging machine with a sealing device, which improves the possibilities of adjusting the sealing parameters such as sealing force, sealing temperature and/or sealing time for various seals within a sealing device and a package, respectively, the term “seal” including hereinbelow also the above-mentioned sealed seams. 
     The packaging machine according to the present invention includes a sealing device, said sealing device comprising at least a first and a second sealing tool for producing a first and a second seal uniting a lower web with a top web. In this packaging machine, actuators can be provided for the sealing tools, by means of which the sealing forces of the sealing tools can be adjusted individually. This is advantageous insofar as the sealing forces for different kinds of seals used for satisfying different demands on a single package can be adjusted independently of one another. 
     The actuators may be provided in the form of diaphragms, pneumatic cylinders or motor drives so as to provide individual control and so as to allow sealing forces of up to 12 kN and sealing pressures of up to 3 N/mm 2 . 
     The packaging machine can include a controller by means of which the sealing force, the sealing temperature and/or the sealing time for the first and second seals can be adjusted separately, so as to be able to provide an automatic changeover of different machine settings for different packages. 
     According to one embodiment, the first sealing tool is provided for producing a sealed seam which extends circumferentially around a product and the second sealing tool is provided for producing a planar seal. By providing different sealing tools, which each have actuators of their own, a change of the respective seal can be accomplished rapidly and easily and without the other seal being affected. 
     According to another embodiment, the sealed seam of the first sealing tool and the seal of the second tool extend adjacent to one another and do not overlap each other, since only a non-overlapping arrangement of the sealing surfaces can exclude that one seal affects the other. 
     The first and second seals can be produced simultaneously so as to avoid any unnecessary extension of the process time required for executing the sealing process for the package. 
     Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
    
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       In the accompanying drawing, which forms a part of the specification and is to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views: 
         FIG. 1  a schematic side view of a thermoform packaging machine according to one embodiment of the present invention; 
         FIG. 2  a schematic sectional side view of the sealing station in the open condition according to one embodiment of the present invention; 
         FIG. 3  a schematic sectional side view of the sealing station in the closed condition according to one embodiment of the present invention; 
         FIG. 4  a schematic sectional side view of the sealing station during the sealing process according to one embodiment of the present invention; 
         FIG. 5  a top view of a package provided with a sealed seam and a planar seal according to one embodiment of the present invention. 
     
    
    
     Identical components are provided with identical reference numerals throughout the figures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures. 
     The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
       FIG. 1  shows a schematic view of a thermoform packaging machine  1  according to one embodiment of the present invention. As illustrated, thermoform packaging machine  1  comprises a forming station  2 , a sealing station  3  (also referred to as sealing device), a transverse cutting device  4  and a longitudinal cutting device  5 , which are arranged in this order in a working direction R on a machine frame  6 . On the input side a supply roll  7  is provided on the machine frame  6 , from which a film  8  (also referred to as lower web) is unwound. In the area of the sealing station  3 , a material storage unit  9  is provided, from which a cover film  10  (also referred to as top web) is unwound. On the output side, a discharge device  13  in the form of a conveyor belt is provided at the packaging machine, with which finished, singulated packages  21  are transported away. Furthermore, the thermoform packaging machine  1  comprises a feeding device which is not shown, said feeding device gripping the film  8  and advancing it in the working direction R during each main work cycle. The feeding device can be realized, for example, by transport chains arranged on either side. 
     In the embodiment shown, the forming station  2  is realized as a thermoforming station, which is used for forming molded troughs and in which troughs  14  are formed in the film  8  by thermoforming. The forming station  2  can be configured such that in the direction perpendicular to the working direction R several troughs are formed side by side. Downstream of the forming station  2 , when seen in the working direction R, an infeed line  15  is provided, along which the troughs  14  formed in the film  8  are filled with the product  16 . 
     The sealing station  3  is provided with a closable chamber  17  in which the atmosphere in the troughs  14  can be substituted, prior to sealing, by an exchange gas or by a gas mixture, for example, by gas flushing. 
     The transverse cutting device  4  can be configured as a punch separating the film  8  and the cover film  10  in a direction transversely to the working direction R between neighbouring troughs  14 . In so doing, the transverse cutting device  4  works such that the film  8  is not cut across the whole width of the film, but remains uncut in at least an edge area. This allows controlled further transport by the feeding device. In the embodiment shown, the longitudinal cutting device  5  is configured as a blade arrangement by means of which the film  8  and the cover film  10  are cut between neighbouring troughs  14  and at the lateral edge of the film  8 , so that, downstream of the longitudinal cutting device  5 , singulated packages are obtained. 
     The thermoform packaging machine  1  is additionally provided with a controller  18 . It is used for controlling and monitoring the processes taking place in the thermoform packaging machine  1 . A display device  19  with operating controls  20  serves to make the sequences of process steps in the thermoform packaging machine  1  visible to an operator and to influence them by the operator. 
     The general mode of operation of the thermoform packaging machine  1  will be described briefly in the following: 
     The film  8  is unwound from the supply roll  7  and conveyed into the forming station  2  by the feeding device. In the forming station  2 , troughs  14  are formed in the film  8  by thermoforming. Together with the material of the film  8  surrounding them, the troughs  14  are advanced, in a main work cycle, to the infeed line  15  where they are filled with the product  16 . 
     Subsequently, the filled troughs  14  are, together with the area of the film  8  surrounding them, advanced by the feeding device into the sealing station  3  during the main work cycle. After having been sealed onto the film  8 , the cover film  10  is advanced when the feed motion of the film  8  takes place. In the course of this process, the cover film  10  is unwound from the material storage unit  9 . By sealing the cover film  10  onto the troughs  14 , closed packages  21  are obtained, which are singulated in the subsequent cutting stations  4  and  5  and removed from the thermoform packaging machine  1  by means of the discharge device  13 . 
       FIG. 2  shows a schematic sectional view of the sealing station  3  comprising a sealing tool lower part  22 , a sealing tool upper part  23 , a first sealing plate  24  and a second sealing plate  25 . The first sealing plate  24  can be adapted to be moved relative to the sealing tool upper part  23  via a first actuator  26  and the second sealing plate  25  can be adapted to be moved orthogonally to the film  8  via a second actuator  27 . Both actuators  26 ,  27  and both sealing plates  24 ,  25 , respectively, are operable separately and the actuators  26 ,  27  may be configured as diaphragms. The first sealing plate  24  can include on the lower surface thereof a product protection plate  28  so that the heat of the sealing plate  24  will only act on the surface to be sealed but not on the product  16 . At this open position of the sealing station  3 , the sealing station has inserted therein a not yet sealed trough  14 , formed of the film  8  and containing the product  16 , and a cover film  10 . 
       FIG. 3  shows the sealing station  3  at a closed position, at which the sealing tool lower part  22  defines together with the sealing tool upper part  23  the closed chamber  17 , so that the chamber  17  and thus also the interior of the trough  14  can be evacuated and/or subjected to gas flushing. 
     After the evacuation and/or gas-flushing process, the actuators  26 ,  27  can be, as shown in  FIG. 4 , activated and move the sealing plates  24 ,  25  against the films  8 ,  10  and the sealing tool lower part  22 , respectively, and generate a first sealing force F 1  for sealing the two films  8 ,  10  with the first sealing plate  24  and a second sealing force F 2  for the purpose of sealing with the second sealing plate  25 . The sealing force F 1  depends (exclusively) on the first actuator  26  and the sealing force F 2  depends (exclusively) on the second actuator  27 . The sealing force F 1  may be different from the sealing force F 2 . In the embodiment shown, the forces can be adjusted by means of the pressures in the first diaphragm  28  and the second diaphragm  30 . If servo drives are used instead of diaphragms, the sealing force can be adjusted via the torque and the motor current. 
       FIG. 5  shows, in a top view of the sealed package  21  produced, a circumferentially extending sealed seam  11 , which hermetically seals the trough  14  of the package  21 , and a planar seal  12  having formed therein an opening  31  through both films  8 ,  10 , said opening  31  being used for suspending the package  21 . The circumferentially extending sealed seam  11  can be produced by means of the first sealing plate  24  with the sealing force F 1  provided through the first actuator  26 , and the planar seal  12  can be produced by means of the second sealing plate  25  with the second sealing force F 2  provided through the second actuator  27 . The sealed seam  11  is sealed such that the package  21  can be opened by pulling the cover film  10  off from the film  8 , whereas the planar seal  12  can be sealed inseparably. 
     The division and arrangement of the first  11  and second seal  12  is not limited to the form shown in  FIG. 5 , other variants are imaginable. The first  24  and the second sealing plate  25  may also be configured such that a plurality of packages  21  can be produced in the sealing station  3  during one sealing process. Likewise, a plurality of actuators for a sealing plate  24 ,  25  is imaginable. The term “sealing plate” comprises, within the framework of the present invention, also sealing tool parts having a different structural design, such as sealing stamps, sealing rails, sealing bars or the like. 
     From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
     The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.