Patent Publication Number: US-2023159204-A1

Title: Device for Sealing Three-Dimensional Objects in the Bag Opening of a Film Bag

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of European Patent Application No. 21 209 486.6, filed 22 Nov. 2021, the contents of which is incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The invention concerns a device and a method for sealing three-dimensional objects in the bag opening of a film bag. Film bags are flexible containers which usually consist of a polymer film. Such film bags may be used for example for packaging or temporary storage of foodstuffs or pharmaceutical products. 
     BACKGROUND 
     Film bags are usually rectangular and have a bag opening on one side. A three-dimensional object is to be sealed in this bag opening, closing the bag opening. The three-dimensional object may be either a flexible object or a rigid object. In this way, for example, foodstuff packagings for fruit purée may be produced, as consumed in particular by young children. A rigid sucking nozzle is sealed into such film bags, via which the child can directly suck the fruit purée out of the film bag. Comparable drinking nozzles are also used in some beverage packagings and are also sealed in the film bag. The drinking or sucking nozzles may be provided with a closure element so that the corresponding film bag can also be closed again. Other areas of application are in principle possible, in particular in the foodstuffs sector and in the pharmaceutical sector. 
     The film bags may be taken ready-made from a stack. Alternatively, the film bags may be produced in an upstream workstation by folding a material web and subsequently welding this web longitudinally and transversely. The double-layer material web produced by folding is open at its upper edge, and can be separated after application, in portions, of the vertical weld seams and lower horizontal weld seams between the vertical weld seams. This gives individual film bags which are not yet closed at the top. 
     Before the three-dimensional object can be sealed in the bag opening, firstly the upper free edges of the bag opening must be pulled apart from one another. If the bag is not correctly opened, the object to be sealed inside cannot be positioned precisely. This may lead to leaking of the film bag. 
     Cyclic flat-bag machines are known, by means of which flat bags are filled with a flat product and then sealed. Here, usually, the flat bag is opened in two working processes. In a first workstation, the bag is picked up by side grippers and transported by means of these grippers to a second workstation. These grippers each clamp one of the two mutually opposing side edges of the bag. In the second workstation, the bags are opened by the two upper bag edges being drawn apart by a respective sucker acting from the outside. Since the upper bag edges move apart from one another during this movement, the side edges of the respective bag must accordingly move towards one another. Consequently, the two grippers must also move towards one another. The outward movement of the suckers must therefore be coordinated with the inward movement of the grippers. This requires a significant control complexity. Because of different bag sizes, this control setup must also be variable in order to allow corresponding adaptations. 
     DE 295 02 128 U1 discloses a flat-bag machine in which the bags are opened during transport from one workstation to the other. In this way, at least one workstation may be omitted. Under comparable conditions, this allows provision of an additional workstation, for example for filling the bags. Thus, several filling stations may be arranged in succession so that the filling product can be composed from several mixing components. The bags may be opened during transport here as the mutual spacing of the two side grippers become smaller, the greater the distance travelled from the first workstation. This may be achieved for example by guides for the grippers which are arranged in a V-shape relative to one another. 
     During sealing of the open bag edge and sealing of three-dimensional object, the bag edge must then be pulled outward again as far as possible so that no folds or channels occur in the sealing seam during the sealing process. Such folds or channels in the sealing seam would cause leaks in the finished bag. The open bag edges are usually tensioned in a separate workstation. This often leads to difficulties in processing small bags. 
     SUMMARY 
     The disclosure provides an improved device for sealing three-dimensional objects in the bag opening of a film bag, which allows as precise a sealing seam as possible around the three-dimensional object. 
     The device for sealing three-dimensional objects in the bag opening of a film bag and a method for sealing three-dimensional objects in the bag opening of the film bag are described. 
     The device for sealing three-dimensional objects in the bag opening of a film bag has a clamp for the film bag, and a heat sealer for sealing a three-dimensional object in the bag opening of the film bag. The clamp has a pair of clamping shoes on each side, between which the edge of the film bag is held. The heat sealer has a pair of sealing jaws between which the bag opening of the film bag can be sealed. The two clamping shoe pairs of the clamp can be moved apart from one another so that the bag opening can be pulled outward and hence tensioned around the object to be sealed. Such a tensioned bag opening allows a clean and precise sealing seam. No folds or channels can be formed in the sealing seam, so no leaks of the film bag can occur. 
     Preferably, the clamping shoes may each be attached to a spring, in particular a bending spring. Such a spring is shaped such that, on movement of the sealing jaws towards one another, a superposed movement of the springs away from one another can take place. On closing of the two sealing jaws, the clamping shoes meet the outer edges of the film bag shortly before the two sealing jaws meet, and clamp said outer edge between them. On further closing of the sealing jaws, the outer edges are pulled outward by the clamping shoes so that the bag opening is held under tension. This pulling apart ensures a smooth bag opening even when a three-dimensional object is to be sealed. This allows a smooth seal without folds and channels. 
     Because of the device for sealing three-dimensional objects in the bag opening of a film bag, no separate station for spreading the bag opening is required. Rather, the complex function of spreading the bag opening can be integrated in a structurally simple component which can easily be adapted to different requirements. Thanks to the compact design of the clamp and the arrangement very close to the sealing jaws, even small bags can be spread rapidly and reproducibly. 
     Preferably, the clamping shoes may be mounted on the respective springs by means of a hinge joint. The contact faces of a clamping shoe pair may thereby always be arranged parallel to the film bag in every position of the springs. 
     In principle, the contact face of the clamping shoes may be configured with an arbitrary surface, for example also with a smooth surface. At least one of the two clamping shoes of a clamping shoe pair may preferably have a profiled contact face. 
     Each contact face of the two clamping shoe pairs may preferably protrude slightly beyond the sealing jaws. In this way, the clamping shoes can grip the edges of film bag and pull these apart in good time before contact with the sealing jaws. 
     The clamping shoes may each be guided in a slotted opening. This allows a simple and secure guidance which can be achieved without great structural complexity. 
     In a particularly advantageous embodiment, the heat sealer together with the clamp is attached to a pair of guide elements. Movement of the clamp is thereby integrated in the closing movement of the heat sealer. In this way, no additional actuators are required so a very compact construction can be achieved. 
     In an advantageous embodiment, the device for sealing three-dimensional objects in the bag opening of a film bag may have a pair of clamping jaws. In this case, the clamping jaw pair is arranged ahead of the sealing jaws. The three-dimensional object to be sealed in the bag opening of a film bag can firstly be compressed by the clamping jaws and thus collapsed before the actual sealing of the flat bag. Such an embodiment is therefore advantageous in particular in the case of flexible valves, while the clamping jaw pair may be omitted for non-flexible valves. Preferably, the clamping jaw pair may be spring-mounted so that the three-dimensional object cannot be accidentally damaged. 
     In principle, the shape of the film bag may be made variable. Thus, even irregularly shaped film bags can be processed with device. 
     Further advantages and features of the invention are given in the claims and in the exemplary embodiment below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described and explained in more detail below with reference to the exemplary embodiment shown in the drawings. In the drawings: 
         FIG.  1    shows a side view of a device for sealing three-dimensional objects in the bag opening of a film bag before closing of the sealing jaws, and 
         FIG.  2    shows a cross-section through the device for sealing three-dimensional objects in the bag opening of a film bag according to  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     The device  10  for sealing three-dimensional objects in the bag opening of a film bag is designed in the present example such that the pre-sealed film bags  12  are sealed lying down with a bag opening  14  on one side. In contrast, it would also be possible to transport and seal the film bags  20  in the standing or hanging position. 
     The pre-sealed film bag  12  is opened in an upstream processing device (not shown here). A three-dimensional object has been placed in the bag opening. The film bag  12  prepared in this way is supplied to the device  10  lying on a support plate  20 . A respective guide element  22 ,  24  is present above and below the support plate  20 . The guide elements  22 ,  24  may be moved towards one another in a vertical movement by a drive unit (not shown here). An upper sealing jaw  26  is attached to the upper guide element  22 , while a lower sealing jaw  28  is attached to the lower guide element  24 . On movement of the guide elements  22 ,  24  towards one another, the sealing jaws  26 ,  28  thus also move towards one another. The bag opening  14  of the film bag  12  may be sealed by the two sealing jaws  26 ,  28  in the region of the support plate  20 . During this sealing of the bag opening  14 , the three-dimensional object  16  is sealed into the bag opening  14 . 
     A clamping jaw  30 ,  32  is spring-mounted on each guide element  22 ,  24 . The clamping jaws  30 ,  32  are here arranged in the region of the film bag  12  just below the bag opening  14 , so that the clamping jaws  30 ,  32  do not obstruct the sealing jaws  26 ,  28 . The clamping jaws  30 ,  32  are also moved on a movement of the guide elements  22 ,  24 . The clamping jaws  30 ,  32  are however offset slightly towards the rear relative to the sealing jaws  26 ,  28 . When the guide elements  22 ,  24  are moved towards one another, the three-dimensional object  16  is initially compressed by the two clamping jaws  30 ,  32  in the region of the bag opening  14  of the film bag  12 . Thus, in the case of a flexible three-dimensional object  16 , a flat seal becomes possible. The two clamping jaws  30 ,  32  are each mounted on the guide elements  22 ,  24  via a spring  34 . Because of the springs  34 , the clamping jaws  30 ,  32  can move such that the two sealing jaws  26 ,  28  can lie against one another and the sealing process can be started. If the three-dimensional object  16  is a non-flexible object, the clamping jaws  30 ,  32  may also be omitted. 
     In the present example, a left clamp  36  and a right clamp  38  are attached to the guide elements  22 ,  24  directly next to the clamping jaws  30 ,  32 . Each clamp  36 ,  38  has a bending spring  40  which is attached by its outer end to the guide element  22 ,  24 . The clamps  36 ,  38  are thus also moved by the guide elements  22 ,  24  so no separate drive is required for the clamps  36 ,  38 . A clamping shoe  42 ,  44  is attached at the inner end of each spring  40 . Thus, in each case an upper clamping shoe  42  and a lower clamping shoe  44  form a clamping shoe pair of a clamp  36 ,  38 . Before the sealing jaws  26 ,  28  meet one another, an upper clamping shoe  42  and a lower clamping shoe  44  grip the side edge region  46  of the film bag  12  and clamp this. On further inward movement of the two sealing jaws  26 ,  28 , the bending springs  40  generate a superposed horizontal movement via which the two edge regions  46  of the film bag  12  are pulled outward. Thus, the bag opening  14  is pulled outward before the actual sealing process, and tensioned around the three-dimensional object  16 . In this way, no folds or channels can occur in the sealing seam. 
     The clamping shoes  42 ,  44  each protrude slightly beyond the two sealing jaws  26 ,  28 . In this way, it can be guaranteed that the clamping shoes  42 ,  44  pull the bag edges  46  outward before the sealing seam is applied. 
     So that the contact faces of the clamping shoes  42 ,  44  always lie parallel to one another—and hence also parallel to the film bag  12 —irrespective of their position, in the present example the clamping shoes  42 ,  44  are each attached to the bending spring  40  via a hinge joint  48 .