Abstract:
A method for automatically attaching a draw string to an infusion bag, in which the draw string surrounds the infusion bag.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method for attaching a draw string to an infusion bag automatically, in which the draw string for squeezing the infusion bag surrounds the infusion bag longitudinally in two laterally offset layers, with the draw string being doubled in each case and inserted through two openings provided in the top part and formed into a loop on one side of the infusion bag, the one section of the draw string leading from each loop is looped around the infusion bag, passed back through the loop and forms a draw section for squeezing the infusion bag and both loops are connected together by means of an intermediate piece in contact with the top part of the infusion bag.  
         [0003]     2. Description of the Prior Art  
         [0004]     An infusion bag of this type is disclosed in EP 1 273 529 A1. This publication, however, does not disclose which process steps are required in order to pull the draw thread through the individual openings and loop it around the infusion bag in an economical manner.  
       SUMMARY OF THE INVENTION  
       [0005]     The purpose of the present invention is therefore to create a method for attaching a draw string to an infusion bag automatically by means of which infusion bags of this type can be manufactured automatically and inexpensively involving only a few process steps. The complexity of the machine required to achieve this should be kept low, and also all malfunctions in the adjustment of the draw string should be avoided to a large extent. Rather, it should be possible for the individual successive adjustment movements of the adjusting elements acting on the draw string to be performed in a straightforward manner, nevertheless at all times it should be guaranteed that the draw string remains securely held in the area of the infusion bag and that the infusion bag is almost completely squeezed out.  
         [0006]     In accordance with the present invention, the method for attaching a draw string to an infusion bag automatically is characterised in that the draw string is initially aligned in a U-shape on one side of the infusion bag at least up to the height of the openings in the top part and is passed through the openings as loops to the other side, that two further loops are then formed in the area of the base of the infusion bag and run in approximately the same way as the loops formed in the area of the top part, and that after this the loops assigned to the base of the infusion bag are passed through the loops held in the top part and are drawn up in order to form the draw sections.  
         [0007]     In this case, it is advantageous for the U-shape of the draw string to be made using a slider adapted to the lateral distance between the two openings provided in the top part of the infusion bag, a draw section or a similar guide element, by means of which the draw string can be deflected between preferably two laterally arranged guide rollers in the direction of the infusion bag.  
         [0008]     The loops assigned to the base of the infusion bag can be formed in a simple manner with the help of two openings worked into the area of the base of the infusion bag or by means of one or two guide elements arranged at a distance from the base, with the draw string being passed through the guide elements or in between them and the base and the loops formed in the area of the base of the infusion bag can be formed with the help of a roller or the like as a guide element, the roller being arranged at a distance from the base with each of the draw strings being passed between the roller and the base.  
         [0009]     In loops formed with the help of a roller as the guide element, the draw string in the area of the base should be guided in cuts worked into or formed into the base.  
         [0010]     It is economical for the loops assigned to the top part and the base of the infusion bag each to be formed by a separate adjusting element, e.g. in the form of a double needle and for the loops assigned to the top part of the infusion bag to be held in place by an adjusting element during formation of the loops assigned to the base, this adjusting element having to be passed through the loops formed in the top part.  
         [0011]     A particularly simple loop can be achieved if the adjusting element used for forming the loops that pass through the top part of the infusion bag is moved to the area of the base, in a preferred embodiment is swivelled and there is released from the loops and that, after this, the loops are formed in the area of the base using this adjusting element. In this procedure, it is only necessary to have one adjusting element configured as a double needle for forming the loops.  
         [0012]     In order to jointly form the loops that pass through the top part and the loops provided in the area of the base, however in order to avoid tangles, two laterally offset hook needles can also be provided that, during the forming of the loops in the area of the base, are twisted, in a preferred embodiment, into a space in the loops assigned to the top part.  
         [0013]     One or both draw sections of the draw string can be provided with tags or the like, in a preferred embodiment in the end parts of the draw sections.  
         [0014]     To facilitate transport of the infusion bag, it is furthermore advantageous for the draw string surrounding the infusion bag to be tensioned after the tag has been attached, for example with the help of an adjustable roller, in such a way that the tag is in contact with the top part of the infusion bag.  
         [0015]     This can be done in such a way that surplus parts of the draw string are stored in the infusion bag or between two chambers after the infusion bag has been squeezed using an adjustable slider or a roller.  
         [0016]     Furthermore, it is advantageous for the two loops formed in the area of the base of the infusion bag to be guided in a block or the like when the loops are pulled tight.  
         [0017]     If infusion bags are produced using the method in accordance with the present invention, this not only guarantees that each infusion bag will be surrounded by two loops aligned in the intended areas in order to squeeze it out but also, above all, that it is possible to manufacture the loops in a short time automatically and economically without any disruptions in the operating sequence. Due to the small number of process steps involved, and the fact that the adjusting elements are almost always adjusted in a straight line, it is therefore assured that excess strains on the draw string, for example at changes of direction, are excluded, which means that the draw string is not be damaged and that interruptions in operation do not have to be accepted.  
         [0018]     Furthermore, the construction complexity for operating the adjusting elements configured as hook needles, double needles or sliders by means of pulling or pushing forces is slight, while the adjusting elements can also be adjusted and controlled without difficulty, therefore it is easy and inexpensive to loop draw strings around infusion bags. The process in accordance with the present invention consequently makes it possible to manufacture infusion bags with two loops without difficulty. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The drawings show the processing sequence by means of which a draw string must be adjusted in the individual sections in order to put two loops around an infusion bag. In the drawings,  
         [0020]      FIG. 1  shows the starting position of the infusion bag and of the draw string to be looped around it,  
         [0021]      FIG. 2  shows the alignment of the draw string by means of a slider,  
         [0022]      FIG. 3  shows the adjustment of an adjusting element for forming the loops that pass through the top part,  
         [0023]      FIG. 4  shows the forming of the loops assigned to the top part as well as the feed movement of an adjusting element for forming the loops that pass through the base,  
         [0024]      FIG. 5  shows the forming of the loops assigned to the base as well as the feed movement of another adjusting element,  
         [0025]      FIG. 6  shows the insertion of the third adjusting element into the loops that pass through the top part and the pickup of the loops that pass through the base,  
         [0026]      FIG. 7  shows the loops that pass through the base being threaded through the loops of the top part,  
         [0027]      FIG. 8  shows the subsequent forming of the loops of the base into draw sections,  
         [0028]      FIG. 9  shows the attachment of a label onto the formed draw sections,  
         [0029]      FIG. 10  shows a sample embodiment for forming the loops assigned to the base of the infusion bag in accordance with  FIG. 5 ,  
         [0030]      FIG. 11  shows the forming of the loops that pass through the top part in accordance with  FIG. 4 ,  
         [0031]      FIG. 12  shows the swivelling of the adjusting element used in the process step shown in  FIG. 11 ,  
         [0032]      FIG. 13  shows the forming of the loops assigned to the base by means of an adjusting element used in accordance with  FIGS. 11 and 12 ,  
         [0033]      FIG. 14  shows the forming of the loops that pass through the base into draw sections,  
         [0034]      FIG. 15  shows the attachment of a label to the tensioned draw sections,  
         [0035]      FIG. 16  shows a first process step for tensioning the label,  
         [0036]      FIG. 17  shows a further process step for tensioning the label,  
         [0037]      FIG. 18  shows the infusion bag with a label touching the top part and with surplus portions of the draw sections stored in the infusion bag,  
         [0038]      FIG. 19  shows the insertion of the parts of the draw sections to be stored between two chambers of the infusion bag by means of a slider and  
         [0039]      FIG. 20  shows the insertion of the parts of the draw sections to be stored in an infusion bag by means of a rod. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]     The infusion bag identified with  1  and shown in whole or in part in FIGS.  1  to  20 , including in different embodiments, is used for holding tea or a similar product which has to be steeped in order to produce a drink, and has a top part  2  and a base  3  into which openings  4  and  5  or  6  and  7  are punched during the processing or are worked in during a previous step in order to be able to accommodate a draw string  11  in a defined position. With the help of the draw string  11  which is looped around the infusion bag  1  twice, it is possible to squeeze out the infusion bag  1  almost completely.  
         [0041]     The draw string  11  is stored on a roller  12 , is cut to the correct length by means of a shear  15  and is looped around the infusion bag  1  in accordance with the following process steps and then finally has a label  10  attached to it. First of all, the draw string  11  is aligned underneath the infusion bag  1  ( FIG. 1 ) and is then moved into the position shown in  FIG. 2  by means of a slider  16 . With the assistance of two rollers  13  and  14  arranged at a distance from one another, the draw string  11  is aligned on the back of the infusion bag  1  in such a way that the draw string  11  runs at the level of the openings  4  and  6  or  5  and  7 .  
         [0042]     Next, as shown in  FIGS. 3, 4  and  5 , a first adjusting element  21  and a second adjusting element  22  that are formed as a double needle are used for forming loops  31  and  32  or  33  and  34 . The loops  31  and  32  are connected together by means of an intermediate piece  35  touching the infusion bag  1  and pass through the openings  4  or  5  provided in the top part  2 , while the loops  33  and  34  pass through the openings  6  and  7  provided in the base  3 . By means of a third adjusting element  23  that is also formed as a double needle and through which loops  31  and  32  are passed, the loops  33  and  34  are picked up in accordance with  FIG. 6  and are pulled through the loops  31  or  32  in accordance with  FIG. 7 . Next, the loops  33  and  34 , that are guided by a block  17 , are pulled on in such a way that these parts of the draw string  11  form two draw sections  11 ′ and  11 ″ to which the label  10  is to be attached.  
         [0043]     The loops  33  and  34  assigned to the base  3  of the infusion bag  1  can also, as shown in  FIG. 10 , be formed with a the help of a roller  18 . In this case, the roller  18  is arranged at a distance from the base  3  so that the draw string  11  can be pulled through between the base  3  and the roller  18  with the help of the adjusting element  22 . The base  3  of the infusion bag  1  could be equipped with notches in this procedure, in order to prevent the draw string from slipping off.  
         [0044]      FIGS. 11, 12 ,  13  and  14  show that both the loops  31  and  32  and the loops  33  and  34  are to be formed with the help of the adjusting element  21 . Once the loops  31  and  32  have been formed, the adjusting element  21  is swivelled in accordance with the line drawn in  FIG. 11 , so that it is located in front of the openings  6  and  7  and can be passed through these in order to pick up the draw string  11  ( FIG. 13 ). Following the complete or partial pulling up of the loops  33  and  34  through openings  6  and  7  and through loops  31  and  32 , the label  10  is attached to the draw sections  11 ′ and  11 ″ ( FIGS. 15 and 16 ).  
         [0045]     Instead of the adjusting element  21 , and as also shown in  FIG. 13 , it is possible for two individual hook needles  24  and  25  to be provided. To prevent any tangles when the hook needles  24  and  25  are being guided back, the needles should be turned inside a space in loops  31  and  32  in such a way that no contact occurs with the draw string  11 .  
         [0046]     So that the label  10  makes contact with the infusion bag  1  when the infusion bag  1  is being transported, as shown in  FIG. 18 , it is advantageous for surplus parts  11 ′″ and  11 ″″ of the draw string  11  to be stored away. As shown in  FIG. 16 , this is to be achieved by means of a roller  19  at the back of the infusion bag  1  to be inserted between the infusion bag  1  and the loops of the draw string  11  and which is moved away from the infusion bag  1  as shown in  FIG. 17 . The loops  31  and  32  are pulled together in this process and the label touches the top part  2  so that the surplus parts  11 ′″ and  11 ″″ of the draw string  11  can be stored in the infusion bag  1 .  
         [0047]     As shown in  FIGS. 19 and 20 , this is to be accomplished with the help of a slider  20  or a roller  20 ′. For this purpose, the slider  20  is pushed through the base  3  of the infusion bag  1  so that the surplus part  11 ″ is inserted between the two chambers ( FIG. 19 ), however in addition as shown in  FIG. 20  it is possible to use the rod  20 ′ for this purpose, which is inserted into the side of the infusion bag  1  and moved in the direction of the top part  2  in order to store the surplus part  11 ′″ of the draw string.