Abstract:
A process for manufacturing a bag from a polymer and/or metal film material provides a bag that has four outer walls connected by four seams and that has a sealed lower end. 
     The bag-forming material is fed in the form of a film web that is wound up on a roll to an unwinding station of a bottom forming device that separates the unwound film web into film segments, connects the film segments, and seals at least one end of the connected segments to form the bag.

Description:
This is a nationalization of PCT/EP2004/002083 filed 13 Feb. 2004 and published in German. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a process for manufacturing bags. Furthermore, the process aims to provide protection for the film tube rolls used in the process. 
     2. Description of the Prior Art 
     Bags are manufactured using, among others, the so-called Form, Fill and Seal Machines, referred to in the following description as FFS machines. 
     Such machines are disclosed in the published patents DE 199 33 486, EP 534 062, DE 44 23 964, DE 199 20478 and DE 199 36 660. The FFS machines have unwinding stations on which film tubes are stored. These unwinding stations unwind the film tubes and separate them into film tube segments. Usually in the later process steps, the film tubes are provided with bottoms, the resulting bag is filled with the filling material and the bag is sealed. The type of bag forming and filling suggested in the aforementioned published patents is also a part of the contents of this disclosure. The same applies to the provisions of the term ‘Form, Fill and Seal machines’ (FFS) and also the processes of transporting the film tubes, film segments and bags into these machines. As a rule, these machines are used to fill the bags with bulk materials. 
     Usually, film tubes are formed by blown film extrusion for the purpose of processing using FFS machines. The format of these film tubes (here, their periphery) is in agreement with the bag formed. This approach necessitates the relatively expensive replacement of formats in the blown film extrusion plants for the purpose of realizing different bag formats. Moreover, the formats required for the bag formation are relatively small and hence cannot be manufactured economically. Blown film extrusion plants of bigger format produce the same foil at much lesser costs per unit of area. 
     Therefore, experiments have been conducted many times with the purpose of first manufacturing very broad film webs by flat film extrusion or by blown film extrusion using machines of a bigger format. Here also, blown film extrusion plants were preferred primarily for cost reasons. The resulting film tubes or film webs of a big format were then processed further to flat film webs by cutting them as per the format required. 
     Subsequently, one of these flat film webs is folded up and joined by a longitudinal joint seam to form a film tube. A disadvantage of such usually very short film tubes is that the thick joint created by the longitudinal joint seam complicates the winding process of the film tube, since the rolled-up film tube tends to telescope, i.e. it assumes a frusticonical shape, due to the addition of the thick joints. 
     Even film tube segments are produced in a similar manner for the purpose of manufacturing bags of a higher quality. Thus, for instance, the manufacture of side-gusset pouches or side-gusset bags are known to prior art that are formed out of several film segments. For this purpose the edges of each of the film segments are usually sealed together. This process is carried out between sealing jaws that clamp the material to be sealed during the sealing process. 
     This method is used generally to manufacture film tube segments whose length corresponds to that of bags formed later. In other cases, immediately after production, the formed film tube segments are cut immediately to the length of the bags formed later and are fed individually to the bag forming, filling and sealing machines. This type of high quality of bag manufacturing is probably well-known in the pet food sector. 
     However, both the transportation of individual film tube segments as well as their insertion into a bag forming, filling and sealing machine is an expensive and complex process. This process is usually executed using rotary feeders or other suction devices that grasp the film tube segments individually and feed them to the bag forming machine. Such devices are expensive and prone to breakdown. 
     SUMMARY OF THE INVENTION 
     Therefore, the objective of the present invention is to provide a process for manufacturing bags from a polymer and/or metal film material in which the feeding process of a film tube material takes place in an easier manner. 
     This objective is achieved by feeding the material required for forming the bags, in the form of a film tube ( 25 ,  40 ), that is wound up into a roll, to the unwinding station of a bottom forming device that separates the unwound film tube into film tube segments and seals at least one end of the bag. 
     It was not possible so far to manufacture film tubes having a length that is desired by the present invention. However, the present description discloses such a manufacturing process. In addition to facilitating the insertion process of the film tubes into the bag forming, filling and sealing machines, the application of the process pursuant to the present invention also involves a reduction in the transportation costs since the rolled up film can be transported conveniently. 
     The process pursuant to the present invention can be carried out using the aforementioned FFS machines. The additional advantage of using these machines is that they have clearly higher filling speeds than the machines used so far for manufacturing and filling the bags specified in the preamble of the claim  1 . The present patent application does not include an illustration of the machine used to execute the process pursuant to this invention. The aforementioned published patents DE 199 33 446, DE 199 20478 and DE 199 36 660 illustrate a class of suitable machines that, in addition to sealing one end of a bag, are also used to fill the bag and seal the other end of the bag. The film tube required for forming the bag is unwound from a roll. The scope of this disclosure aims at achieving these characteristics and forms the content of the present patent application. 
     The shape of the film roll even prior to its formation, is also accorded a great deal of attention in the following description. 
     Further scope of applicability of the present invention will become apparent from the detailed description and claims given hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The individual figures illustrate: 
         FIG. 1  A side view of a machine pursuant to the invention 
         FIG. 2  A top view of the machine pursuant to the invention illustrated in  FIG. 1   
         FIG. 3  The cross-section I-I of the machine illustrated in  FIG. 1   
         FIG. 4  A sketch of the course of path before the roller clearance  50   
         FIG. 5  A cross-section of a film tube pursuant to the invention 
         FIG. 6  A cross-section of an additional film tube pursuant to the invention 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     The figures illustrate a machine  1  whose functioning is described below particularly in terms of the path of the film web E through the machine  1 . The machine comprises an unwinding station  2  that unwinds the film web E. The film web E is transported, as indicated by the arrow in the direction z of the axis of the film tube that is formed subsequently, and is fed by means of the deflecting rollers  3  and  4  to the cutting station  5  that is symbolized here only by the line II-II. The cutting station comprises cutting tools (not illustrated) that are used to cut the web E into the webs A, B, C and D. 
     The film web A is turned twice on the turning bars  6  and  7  so that it reverses its direction and is finally fed along the direction z to the joining station  8 . In this context it must be mentioned that the turning bar  6  is displaceable in the z-direction so that the longitudinal register of the film web A can be adjusted here. This instance is marked by the arrow  45 . 
     The film web B is guided by means of the rollers  9  and  10 , the turning bar  11  and the roller  12 . At this juncture, it moves temporarily in the x-direction. The film web moves above the joining station  8  by means of the roller  13  that guides it in the direction of the roller clearance  50  between the squeegee rollers  14  and  15 . The film web moves between the roller  13  and the roller clearance  50  across a triangle  51  made of section tubes illustrated in  FIG. 4 . The film web B that was flat previously is folded in this manner so that soon after being squeezed by the squeegee rollers  14  and  15  a clearly defined folded edge is formed in the roller clearance  50  that forms a side gusset  26  in the finished film tube  25 . Additional components of the machine pursuant to the invention are not illustrated in  FIG. 4 . 
     The longitudinal register of the film web B can also be corrected by displacing the roller  12  in the x-direction (arrow  46 ). 
     The film web C is first guided by means of the rollers  9 ,  16 ,  17  and  19  where the arrow  20  marks the adjustability of the roller  18  in the y-direction, which again enables a correction of the longitudinal register of the film web C. After passing the roller  19 , the film web C moves using the turning bar  21 , then moves in x-direction toward the roller  22  which turns the film web C downward in the direction of the roller clearance  50  defined by the squeegee rollers  14  and  15 . A side gusset is formed by the folded edge in film web C similar to the aforementioned processing of film web B: After being deflected by the roller  22 , the film web C moves across a triangle (not illustrated) made of section tubes whose vertex points toward the roller clearance  50 . The film web C thus arrives in the roller clearance  50  in a folded manner. It must be noted here that there are also other alternatives of forming folded edges on film webs and forming side gussets on film tubes or bags that can also be used in the machine pursuant to the invention. 
     The flat film web D moves through the cutting station  5 , then using the rollers  9 ,  23 ,  30  into the roller clearance  50  defined by the squeegee rollers  14  and  15 . The adjustability of the roller  23  in the y-direction marked by the arrow  24  enables a correction in the longitudinal register of the film web D. 
     Thus in the illustrated embodiment of the machine  1 , all the film webs A-D required for forming the film tube are joined together in the joining station  8  or more precisely in the roller clearance  50  defined by the squeegee rollers  14  and  15 . 
     Two extrusion devices  31  provide extrudate in order to join the joint seams  27  firmly to one another. Strictly speaking, the extrudate is supplied in the extruder  32  in which an extruder screw generates high pressure. The extrudate is transported by means of the extruder arms  33   a, b  and using the roller clearance  50  to the joining station  8 . Here the extrudate is extruded by the nozzles  34   a, b ,  35   a, b  provided for this purpose onto the edges of the film webs A-D that are joined to one another in the roller clearance  50  immediately after this process. 
     Usually the extrudate is applied in a heated state so that its coagulation joins the film webs more tightly. Polyolefins can be used as extrudates. However, it is also possible to use all forms of adhesives or to weld the edges of the film webs. 
     The film tube  25  is formed soon after leaving the roller clearance  50 . First it is conveyed in the direction of the gravitational force. This alignment of the film tube is advantageous for solidifying the joint seams  27  and/or for distributing the extrudate. 
     Finally the film tube  25  moves by means of the rollers  38  and  35  to the winding station  36  that is illustrated symbolically in the figures.  FIGS. 1 to 3  also illustrate the motor  60  that transfers a torsional moment on the extruder by means of a belt that is not illustrated, a fan  61  and the machine frame  37 . Additional adhesive elements of other machine components such as rollers or guide rods are not illustrated since the bearing and mounting of such components are obvious to those skilled in this art. Similarly, other machine components that are well-known in principle, such as the winding and unwinding stations are illustrated symbolically. 
       FIG. 5  illustrates the cross-section of a film tube  25  for a bag manufactured by the machine pursuant to the invention.  FIG. 5  illustrates the film webs A-D, the joint seams  27  joining them and also the side gussets  26 . 
       FIG. 6  illustrates another cross-section of a bag pursuant to the present invention. The film tube  40  illustrated in  FIG. 6 , like the film tube  25  illustrated in  FIG. 5 , comprises four joined seams  27  that join the four film webs M, N, O, and P to one another. As opposed to the film tube  25 , film tube  40  has no side gussets  26 . 
     In conclusion, it must be stated emphatically that the illustrated film tubes pursuant to the present invention can also be processed further to manufacture end products other than FFS-bags. Particularly, the side-gusseted film tube  25  can be used in various applications. 
     Finally, it must also be mentioned that the  FIGS. 5 and 6  also illustrate a film tube whose joined seams  27  join entire layers of film or material (A-D) to one another. 
     The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of reference symbols 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  1 
                 Device pursuant to the invention 
               
               
                  2 
                 Unwinding station 
               
               
                  3 
                 Deflecting roller 
               
               
                  4 
                 Deflecting roller 
               
               
                  5 
                 Cutting station 
               
               
                  6 
                 Turning bar 
               
               
                  7 
                 Turning bar 
               
               
                  8 
                 Joining station 
               
               
                  9 
                 Roller 
               
               
                 10 
                 Roller 
               
               
                 11 
                 Turning bar 
               
               
                 12 
                 Roller 
               
               
                 13 
                 Roller 
               
               
                 14 
                 Squeegee roller 
               
               
                 15 
                 Squeegee roller 
               
               
                 16 
                 Roller 
               
               
                 17 
                 Roller 
               
               
                 18 
                 Roller 
               
               
                 19 
                 Roller 
               
               
                 20 
                 Arrow 
               
               
                 21 
                 Turning bar 
               
               
                 22 
                 Roller 
               
               
                 23 
                 Roller 
               
               
                 24 
                 Arrow 
               
               
                 25 
                 Side-gussetted film tube 
               
               
                 26 
                 Side gusset 
               
               
                 27 
                 Joint seam 
               
               
                 28 
                 Blind seams 
               
               
                 29 
               
               
                 30 
                 Roller 
               
               
                 31 
                 Extrusion device 
               
               
                 32 
                 Extruder 
               
               
                 33 
                 Extruder arms 
               
               
                 34 
                 Nozzle, nozzle area 
               
               
                 35 
                 Roller 
               
               
                 36 
                 Winding station 
               
               
                 37 
                 Machine frame 
               
               
                 38 
                 Roller 
               
               
                 40 
                 Film tube 
               
               
                 41 
                 Film tube pursuant to the invention 
               
               
                 42 
                 Film tube 
               
               
                 45 
                 Longitudinal register of the film web A 
               
               
                 50 
                 Roller clearance 
               
               
                 51 
                 Triangle made of section tubes 
               
               
                 60 
                 Motor 
               
               
                 61 
                 Fan 
               
               
                 A-E 
                 Film webs 
               
               
                 U 
                 Path of the flat film tube 
               
               
                 V 
                 Path of the flat film tube