Abstract:
The invention relates to a process of and device for handling an upright filled bag with a closed bag flap while the bag flap is being sewn in a sewing station. The device comprises two pivotable arms with clamping means which is able to fix the closed bag flap underneath a sewing line, as well as feeding means for the arms by means of which the clamping means can be guided underneath past a sewing position.

Description:
FIELD OF INVENTION  
       [0001]     The invention relates to a process of and a device for handling an upright filled bag with a closed bag flap while the bag flap is being sewn in a sewing station.  
       BACKGROUND OF THE INVENTION  
       [0002]     Previously it has been common practice for bags which are filled with bulk material and whose bag flap has already been folded so as to be in a flat position and, optionally, has been folded over twice, during the horizontal transport towards a sewing station, to be gripped by stationary guiding belts extending in opposite directions for the purpose of moving the bag flap into the sewing station. The ends of the guiding belts are positioned in front of a sewing station, i.e. in front of the position of the sewing needle and are removed from the sewing needle far enough for the part of the bag flap emerging from the guiding belts to experience a certain amount of lateral support on the part of the guiding belts when reaching the sewing position. Nevertheless, the bag in the sewing station may suffer damage which is primarily due to the fact that the bag is fed in the direction of the bag flap continuously, whereas the sewing operation carried out by the fixed sewing needle is of a discontinuous nature during which the needle piercing the bag flap holds the bag flap in the direction of feed, with the bag flap being released after having been pulled away from the sewing needle.  
         [0003]     For bridging larger transport distances between a bag filling station and a bag closing device, more particularly a sewing device, previously there have been proposed transfer devices which clamp in a filled bag at the bag flap and guide same synchronously with the speed of the conveyor belt. Such devices comprise two pivotable arms with clamping means for the bag flap. However, they release the bag flap prior to moving into the bag closing device (See DE 95 37 795 C1, EP 0 559 952 B1).  
       OBJECT OF THE INVENTION  
       [0004]     It is the object of the present invention to provide a process and device by means of which the sewing process can be improved and which avoids damage at the bag flap during the sewing operation.  
       SUMMARY OF THE PREFERRED EMBODIMENT  
       [0005]     The inventive process for achieving the object of this invention provides that the bag flap, when passing through the sewing station, is clamped in underneath a horizontal sewing line with clamping means which can be guided past underneath a sewing station, and is thus held so as to be fixed. Herein it is preferably proposed that the bag flap is held resiliently in the passing direction when passing through the sewing station. The sewing line usually is oriented horizontally.  
         [0006]     The inventive device for achieving the object of this invention has also two pivotable arms with clamping means which are able to fix the closed bag flap underneath a sewing line and feeding means for the arms, by which the clamping means can be guided underneath past a sewing station. Preferably the clamping means is resiliently arranged in the transportation and sewing direction at least at one of the arms. Corresponding to the orientation of the sewing line, the clamping means is arranged parallel to the latter, i.e. also preferably horizontally.  
         [0007]     These measures ensure that the bag flap runs into the sewing device in a guided way, so that even if the internal stability of the bag flap is low, a proper and accurate sewing operation can be carried out. Therefore, in contrast to prior art guiding belts, the handling means are not arranged so as to be stationary, instead they move synchronously with the bag underneath the sewing position. The clamping means can be provided with a certain amount of internal elasticity, for instance they can be provided in the form of rubber elements or rubber/metal elements in order to comprise a certain degree of elastic resilience in the longitudinal direction of the bag flap. In this way, it is possible to reduce the transverse forces which act on the sewing needle as a result of the continuous feeding movement of the bag flap.  
         [0008]     According to a preferred embodiment, the clamping means comprise a strip at one of the arms and the two stoppers at the other one of the arms, which arms can be made to contact one another in order to clamp in the closed bag flap at its ends. More particularly, it is proposed that the stoppers can be adjusted relative to one another to be able to be adapted to bags of different widths. Also, the fact that the bag flap is effectively clamped in by the stoppers at two points only ensures a certain resilience of the bag flap in the longitudinal direction with a view to reducing the undesirable transverse forces at the sewing needle.  
         [0009]     By providing that the die clamping means, more particularly the strip, is resiliently arranged at least at one of the arms in the longitudinal extension of the bag flap, the resilience of the clamping device is achieved particularly effectively. The spring stiffness can be adjusted in such a way that each time the sewing needle pierces the bag flap, the resilient clamping means can give against the direction of feed the bag flap.  
         [0010]     According to a preferred design, the one of the arms to which the resilient clamping means are attached comprises two levers, and the resilient clamping means are held by two fixing brackets, with the levers and the fixing brackets being connected to one another in pairs via spring plates. In this way, it is possible to achieve a wide support for the resilient clamping means.  
         [0011]     Furthermore, it is proposed that the horizontal distances between the levers of said arm and between the fixing brackets slightly deviate from one another and that the spring plates, in the starting condition, are cranked so as to be S-shaped in opposite directions. The spring movement is thus restricted in every direction for the reason that, after a predetermined path, the spring plates come into planar contact with one of the parts arranged relative to one another in a slightly offset way.  
         [0012]     Above, there have been described clamping means consisting of a strip on the one hand and of two stoppers on the other hand. However, it is also possible to provide pairs of stoppers or a larger number of pairs of stoppers at both arms. Furthermore, it is possible to arrange the clamping means resiliently at both arms in the direction of the bag flap, for example with spring plates of the above-described type integrated into both arms.  
         [0013]     Preferred embodiments of the invention are illustrated in the drawings and will be described below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a perspective view illustrating the inventive device with a clamped-in bag in a sewing station.  
         [0015]      FIG. 2  is a perspective view illustrating the inventive device with a clamped-in bag without the sewing station.  
         [0016]      FIG. 3  is a perspective view of one of the arms of the inventive device.  
         [0017]      FIG. 4  is a perspective view of the other arm of the inventive device.  
         [0018]      FIG. 5  illustrates the resilient way in which the clamping means are fixed at one of the arms. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]      FIG. 1  shows part of a sewing station illustrating the sewing machine  11  which is provided with a pivot axis  12  held in a pivot bearing  13 . In the drawing, the sewing machine  11  is shown in its operating position. It comprises a portal  14  through which it is possible to guide a filled bag  16  for the purpose of being sewn up. A sewing unit with a horizontally arranged sewing needle is positioned inside said portal. During the sewing operation, the bag  16  is held by an inventive device  17  at the bag flap below a horizontal sewing line  34  determined by the position of the sewing needle. The device  17  comprises two multi-component movable arms  18 ,  19  with clamping means which, by setting cylinders (not illustrated), can be pivoted away from the bag flap  15  or which, with the bag flap being clamped in, can be made to contact one another on identical levels. The device  17  can be moved in its entirety in the direction of the bag flap  15  together with the bag  16 . The arms  18 ,  19 , more particularly, can be connected to a slide, which at the same time carries and moves the bag itself in order to ensure a synchronous movement between the bag  16  and the device  17 .  
         [0020]      FIG. 2  shows the device  17  with the bag  16  without the sewing machine. This Figure shows more clearly that the arms  18 ,  19  are designed differently. The arm  18  comprises two levers  20 ,  21  which are designed to be parallel and are supported in two pairs of pivot arms. The levers  20 ,  21  carry two fixing brackets  22 ,  23  to which a horizontal strip  26  is directly attached. The levers  20 ,  21  are connected to the fixing brackets  22 ,  23  via spring plates  24 ,  25  which resiliently hold the fixing brackets  22 ,  23  and thus the strip  26  in their longitudinal direction at the levers  20 ,  21  which are substantially rigid. The second arm  19  comprises two levers  28 ,  29  which directly carry a guiding strip  27  to which two individual stoppers are axially adjustably fixed. The stoppers are adjusted in such a way that they fix the bag flap  15  of the bag  16  along the greatest possible length against the strip  26 . The arms  18 ,  19  are secured to multi-component supports  30 ,  31 .  
         [0021]      FIG. 3  shows the arm  19  as a detail The two levers  20 , 21 , the two fixing brackets  22 ,  23  and the spring plates  24 ,  25  with their bolts are clearly visible. It should be pointed out that the bolts are attached at the levers  20 ,  21  at the outermost ends of same, whereas the bolts at the fixing brackets  22 ,  23  are arranged at a distance from the free ends of same. The axial distance between the levers  20 ,  21  is greater than the axial distance between the fixing brackets  22 ,  23 , with the spring plates  24 ,  25  being cranked so as to be S-shaped, the result being that the strip  26  can be deflected in its longitudinal direction in the one or the other direction against the returning force of the spring plates until the front one (in the direction of movement) of the fixing brackets contacts its spring plate in a planar way. The spring travel of the strip  26  is thus delimited by simple means. The strip  26  can be a rubber/metal element.  
         [0022]      FIG. 4  shows the arm  19  together with its details. A bar  27  on which there are horizontally adjustably arranged conical stoppers  32 ,  33  in the direction of the bar  27  are directly firmly arranged at the levers  28 ,  29 . As described above, by pivoting the arms, the stoppers  32 ,  33  can be made to contact the above-mentioned strip  26 . The movement of the resiliently supported strip  26  can be copied, substantially, by the stoppers  32 ,  33  provided in the form of resilient conical rubber elements. The same applies to the bag flap clamped in between the stoppers and the strip.  
         [0023]      FIG. 5  shows the front end of the arms  18  as well as part of the pivot arms and of the levers  20 ,  21 . It is also possible to see the strip  26  and the fixing brackets  22 ,  23  attached thereto, as well as the spring plates  24 ,  25 . It can be seen quite clearly that the distance between the levers  20 ,  21  in the longitudinal direction of the strip  26  is greater than the distance between the fixing brackets  22 ,  23 . The spring plates are firmly bolted to the levers  20 ,  21  by means of first groups of bolts  36 ,  37 . However, the second groups of bolts  38 ,  39  have not yet been firmly bolted to the levers  20 ,  21 . Therefore, the spring plates  24 ,  25  are still in a planar starting condition and are arranged at a distance from the fixing brackets  22 ,  23 . When tightening the groups of bolts  38 ,  39 , the spring plates are symmetrically cranked relative to one another into an S-shape. In consequence, when the strip vibrates in the longitudinal direction, the path is delimited in that one of the fixing brackets  22 ,  23  establishes a planar contact with the respective spring plate springing back into its planar starting condition. A rubber lip  35  is bolted to the strip  26  consisting of metal.