Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a national stage of PCT/EP11/057844 filed May 16, 2011 and published in German, which has a priority of German no. 10 2010 029 139.0 filed May 19, 2010, hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a device for generating hose sections, which essentially comprise paper to produce bags, as well as a method of producing hose sections that employs the aforementioned device. 
     2. Description of the Prior Art 
     In order to produce bags, first a web is wound off an unwinding device. This web essentially comprises paper, however sections may be provided here, for example windows made from plastic. Various perforations are inserted into the web by a perforation device. One of these perforations extends from one edge to the second edge in order to later allow that the web can be torn off along these perforations to form web or hose sections in a separating device. However, prior to this tearing process the web is generally connected to form a hose. The individual hose sections are later provided with a bottom and then form bags. The patent application DE 10 2005 052 129 of the applicant discloses such a device. 
     Perforation devices of prior art comprise perforating knives adjusted to the desired perforation contour, i.e. they need to be exchanged. This leads to long down times during which the machine cannot produce. Additionally, various knives and their fasteners must be provided in the warehouse for the different contours and/or widths of webs. The perforating knives are also subject to wear and tear. Neither long down times nor warehousing tools or wear and tear are desirable. 
     SUMMARY OF THE INVENTION 
     The objective of the present invention is therefore to suggest a device and a method for avoiding the above-mentioned disadvantages. 
     The objective is attained in a device as described herein, and in a method as described herein that employs the aforementioned device. 
     Accordingly it is provided that the perforation device comprises at least one laser beam device, by which at least one laser beam can be guided to the web in order to insert the perforations. 
     A laser beam device is characterized in emitting a strongly coherent and bundled light. Due to the above-mentioned features of the light it is very energy intensive and thus capable to remove the web material in the areas in which it impinges the web. Here, the light must be guided via one or more rapidly moving reflectors to various points of the web so that different cuts can be generated. For example, very fine perforation cuts can be produced, which after tearing off are hardly discernible as such. The bags produced in this manner are therefore very appealing. 
     Additionally, here frequently higher stability of the perforated material web results. This particularly applies for the use of film components. 
     The device improved in this manner avoids the down times for changing knives. Here, only the motion data for the reflector and/or the laser device must be stated. Based thereon, a control device controls the actuators of the reflector. Such motion data can also be calculated based on different parameters, of course. Due to the fact that different motions are possible, accordingly the contour of perforations can be designed with considerably more varieties. 
     Due to the fact that knives are no longer necessary any warehousing thereof is omitted. Additionally, wear and tear of knives and other components, such as the counter roll for example, are no longer relevant. 
     In a particularly advantageous further development of the invention it is provided that the web can be guided over at least one web guiding or web deflection device, which is adjustable in its relative position in reference to the laser beam device. In particular it is advantageous for at least the web guiding or web deflection device to be displaceable in the vertical direction. 
     The advantage of these further developments become obvious in the following: Using the device mentioned at the outset for generating hose sections generally hoses or webs of various widths are processed. The laser beam guided by the laser beam device on the web can only cover a certain maximum width of the web, though, because a wide adjustment range of the reflector necessary to deflect the beam would require large adjustment paths. This adjustment range is therefore limited. In case of large distances of the web from the laser beam device a wide web can also be exposed over its entire width. A short distance of the web is desirable, though, because here the beam can be better focused and thus the radiation energy can be transferred more efficiently. In order to keep the distance as short as possible and here allowing to guide the beam even over the entire width of the web it is particularly advantageous to embody the web guiding or web deflection device adjustable in its relative position in reference to the laser beam device. 
     In another embodiment of the invention it is provided that at least one web guiding or web deflection device comprises at least one lateral stretching element. In conventional perforation knives the web, as already mentioned, travels over a counter pressure roll. Such a counter pressure roll or a counter element of any kind is always disadvantageous when using laser light, since the latter can damage the counter element. Accordingly it is provided to keep the web at a certain stress in the lateral direction by a lateral stretching element, so that the laser light impinges a planar web. This way, a good perforation cut can be ensured. A device for adjusting or controlling the web tension serves for the same purpose, ensuring an appropriate web tension in the longitudinal direction. 
     In another advantageous exemplary embodiment of the invention it is provided for the web guiding or deflection device to show at least one guiding sheet or at least one guiding table. Such guiding sheets or guiding tables are capable to guide the web along a level such that good cutting results are yielded with laser light. Of course, in this arrangement it must be ensured that the laser light is prevented from damaging the above-mentioned guiding elements. 
     Accordingly, in another embodiment guiding sheets are provided in the areas subject to the laser light, provided with recesses. In such an arrangement it is additionally advantageous for the guiding sheets to be displaceable in reference to each other in the travel direction of the web. This is necessary when the transverse speed of the laser (thus the speed by which the laser is guided perpendicularly in reference to the travelling direction of the web) and/or the travelling speed of the web can be adjusted. As soon as the web is moved the laser beam, which is only punctual, must also be moved, at least partially, with the travelling speed of the web in its direction of transportation when a perforation cut shall be performed perpendicular in reference to the web. 
     It is further advantageous for the perforation device to comprise at least one suction device, in order to allow removing paper dust developing, on the one hand, as well as sections or cut-out sections, on the other hand. 
     Instead of web guiding or deflection devices displaceable or changeable in their position it may also be provided to implement the laser beam device adjustable in its position in reference to the web. 
     Additional exemplary embodiments of the invention are discernible from the present description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The individual figures show: 
         FIG. 1  a side view of a bag machine of prior art, 
         FIG. 2  a side view of a first embodiment of a device according to the invention, 
         FIG. 3  a side view of a second embodiment of a device according to the invention, 
         FIG. 4  a detail of a perforation station of  FIGS. 2 and 3 , 
         FIG. 5   a  a view V-V of  FIG. 4  with a narrow web, 
         FIG. 5   b  a view V-V of  FIG. 4 , however with a wide web, 
         FIG. 6   a  a view VI-VI of  FIG. 4  with a slow web speed, 
         FIG. 6   b  a view VI-VI of  FIG. 4  with a faster web speed, 
         FIG. 7  a side view of another embodiment of a device according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Further scope of a 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. 
       FIG. 1  shows a device  1  for producing bags, as known from prior art. This figure schematically shows the essential components of this device. The device  1  comprises an unwinding device  2  in the form of an unwinding device  4 , to which a material web  3  is guided. Starting from this unwinding device  4  the web  3  is fed via guiding rolls  5  to the lateral cutting station  6  and/or the perforation station  6 . This station  6  comprises one or more lateral cutting or lateral perforating knives, not shown in greater detail, rotating on a roll  7 . In this station  6  the material web  3  travels over a counter pressure roll  8 , which serves the purpose to provide the necessary counter pressure for the cutting or perforating process. In this cutting or perforating process the web is not separated but provided with weakening cuts or perforations along which later the hose to be formed is torn for separation into hose sections. Additionally, perforations serving for a later tearing of individual, additional material sections from the hose section, may be inserted into the material web in the described station  6 . For this purpose, the roll  7  may show knives at certain sections, arranged parallel in reference to each other. 
     Subsequently the material web  3  travels through a gap, which is formed by another guiding roll  5  and a roll embodied as a longitudinal adhesion device  26 . Instead of a roll, the longitudinal adhesion device may also comprise an adhesive applying nozzle. The roll or the nozzle applies an adhesive onto a lateral section of the material web  3 , in order to lastingly connect the two lateral sections to each other after the hose has been formed, as described in the following. 
     In the following hose forming station  9  a hose  10  is formed from the material web  3 , by the web  3  being laterally folded over by guiding elements, such as guiding sheets, for example, so that the edges of the material web then overlap. The overlapping sections have already provided with an appropriate adhesive using the longitudinal adhesion device  26 . During the folding over of the paper web lateral folds can also be created. The insertion of the lateral folds may also occur after the hose formation. The hose  10  is now usually guided further in the traveling direction z. 
     After the hose  10  has been created, it is separated in the tearing station  11  into hose sections  12 . For this purpose the hose  10  is guided through the roll gap of a first pair of rolls  13 . During the further progression of the hose it reaches the roll gap of a second pair of rolls  14 . The rolls of the second pair of rolls show constantly or at least temporarily a greater circumferential speed than the rolls of the first pair of rolls  13 , with their circumferential speed coinciding with the traveling speed of the hose  10  or being slower than it. When the next perforation has passed the roll gap of the first pair of rolls  13 , seen from the preceding end of the hose, the second pair of rolls  14  engages the hose  10 . This can occur by the preceding end of the hose entering the roll gap of the second pair of rolls. The rolls of the second pair of rolls  14  can also be moved relative in reference to the hose  10 , for example perpendicularly, and contact the hose. When the rolls of the second pair of rolls  14  contact the hose, said hose is torn along the cut and/or the perforation. 
     The hose section  12  torn off the hose now reaches the bottom adhesion and/or bottom folding station  15 . For this purpose, the hose section  12  is held on the bottom generating cylinder  16 . Using a suitable element, for example a rod, the flap of the hose section traveling ahead, which generally is a component of the bottom projecting the top, is folded over so that parts of the bottom layer, after the folding process, rest on the exterior of the upper layer. Before that, the flap and/or the section of the exterior of the upper layer with the flap resting thereupon after the folding process are provided with an adhesive, for example glue. The adhesive application device serves for this purpose, symbolized in  FIG. 1  by the glue cylinder  17 . 
     After the bags have been produced to this extent, the bag is placed by the bottom generating cylinder onto a table  22 . Here, the bags are generally arranged standing upright. Then the bags can be removed from this table  22  in stacks in an appropriate fashion. 
       FIG. 2  shows the device according to the invention in which the perforation station  6  of prior art has been replaced by such a perforation station  30  which processes the web  3  with a laser beam instead of a knife. This station may replace the known perforation station, for example, in the machine frame  21 . 
       FIG. 3  shows an alternative embodiment of the perforation station  30  in the device according to the invention. Here, a separate frame  29  is provided, in which the perforation station  30 , but also the unwinding device  4  are arranged. The advantage of such an arrangement is the fact that machines of prior art can be retrofitted into a device according to the invention by adding a frame  29 . The design and the function of the perforation station  30  are identical, independent from their arrangement, and in the following they are explained in greater detail based on the figures. 
       FIG. 4  shows the perforation station  30  in an enlarged view. The web  3  is first guided via a deflection roll  31  and then passes the deflection roll  32 , which deflects the web  3  in a preferably horizontal level. Here, it is advantageous for the deflection roll  32  to be embodied as a laterally stretching roll in order to stretch the web  3  perpendicularly in reference to its extension such that it remains in one level. The following roll  33  is once more advantageously embodied as a laterally stretching roll acting as a deflecting roll, which guides the web to the deflection roll  34 . Advantageously a laser beam arrangement  35  is arranged above the level defined by the web  3 . This laser beam device  35  comprises a laser beam source and one or more reflectors, by which the laser beam  39  can be reflected to the desired position on the web. The reflector or reflectors are preferably adjustable via mechanic means. Such laser beam devices are frequently also called laser scanners. The laser beam device  35  is designed such that the laser beam can be moved in two dimensions. 
     The deflection rolls  32  and  33  can be supported in a frame  36 , which can be displaced in reference to the laser beam device. The preferred direction of adjustment extending perpendicular in reference to the level of the web  3  is represented by the arrow  37 . 
     The frame  36  may be supported displaceable in various rails. The height adjustment may occur by a manually or electromotive operated spindle elevator. Using the above-described height adjustment it can be ensured that the laser beam, which due to the limited ability for adjustment of the laser scanner can only scan a certain angle perpendicular in reference to the traveling direction z of the web, may also perforate it over its entire lateral direction, even in wider webs. The dot-dash lines respectively show the frame and the parts arranged thereat in positions adjusted in their height. 
     Furthermore, a collection bin  38  may be provided, which is also supported advantageously on the frame  36 . A suction nozzle  40  may be provided at the collection bin  38  by which refuse or paper dust can be suctioned off via a suctioning device. Another suction nozzle  41  may serve the same purpose. 
       FIGS. 5   a  and  5   b  show the view V-V of  FIG. 4 , with  FIG. 5  illustrating the height adjustment for a narrow web and  FIG. 5   b  the height adjustment for a wide web. The angle α, which the laser beam  39  can scan, is always the same. 
       FIGS. 6   a  and  6   b  show another embodiment of the invention. The web  3  guided via the rolls  32  and  33  is additionally supported at its edges by sheets  42  and  43 . The sheets show recesses  44  and  45 , by which the laser beam  39  can be guided in order to prevent the sheet becoming damaged by the radiation. 
     At least one of the sheets can be moved in the direction of operation of the web z and opposite thereto. This way, a laser can be moved at various angles b in reference to the lateral direction y of the web. In steady traverse speeds of the laser beam this angle can be adjusted depending on the web speed v. Here, in  FIG. 6   a  a first web speed v 1  is adjusted, which requires a first angle β 1 . In web speeds v 2  greater than v 1  the angle β 2 , which is greater than β 1  must be adjusted. Accordingly in  FIG. 6   b  the sheet  42  was displaced in the travel direction z such that the laser beam also impinges the recess at the changed angle β 2  and abstains from damaging the sheet. 
     The sheet or sheets can be embodied manually displaceable. However it is beneficial for a motorized, for example an electromotive adjustment device to be provided, controllable by a control device, also controlling the laser beam. 
     Instead of two separated sheets, several coupled sheets may also be provided, which can be adjusted via joint adjustment mechanisms. For example, a laterally extending pivotal level may be arranged articulate at several sheets. Instead of sheets, other suitable components may also be used, suitable to support the web such that it is located in a single level. It may represent brushes or small rolls, for example. 
       FIG. 7  shows another exemplary embodiment of the invention. In this case, the laser  35  radiates rather horizontally, with the web  3  being guided vertically. The dual arrow  37  here points in the horizontal direction. This means that the deflection rolls  31  and  32  can be changed in the horizontal direction in their position in reference to the direction of the laser beam  35 . The deflection roll  33  may be supported locally fixed, however. Other arrangements of the web guiding or web deflecting devices are also possible, which can be changed in their relative position in reference to the laser beam device. Although these options are not listed in detail, they are included in the scope of the invention described in this application. 
     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 characters 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 device for producing bags 
               
               
                 2 
                 unwinding device 
               
               
                 3 
                 material web 
               
               
                 4 
                 roll 
               
               
                 5 
                 guiding roll 
               
               
                 6 
                 lateral cutting station/perforation station 
               
               
                 7 
                 roll 
               
               
                 8 
                 counter pressure roll 
               
               
                 9 
                 hose forming station 
               
               
                 10 
                 hose 
               
               
                 11 
                 tear-off station 
               
               
                 12 
                 hose section 
               
               
                 13 
                 first pair of rolls/pair of holding rolls 
               
               
                 14 
                 second pair of rolls/pair of tear-off rolls 
               
               
                 15 
                 bottom adhesion and folding station 
               
               
                 16 
                 bottom generating cylinder 
               
               
                 17 
                 glue cylinder/folding knife 
               
               
                 18 
               
               
                 19 
               
               
                 20 
               
               
                 21 
                 machine frame 
               
               
                 22 
                 table 
               
               
                 23 
               
               
                 24 
               
               
                 25 
               
               
                 26 
                 longitudinal adhesion device 
               
               
                 27 
               
               
                 28 
               
               
                 29 
                 frame 
               
               
                 30 
                 perforation station 
               
               
                 31 
                 deflection roll 
               
               
                 32 
                 deflection roll 
               
               
                 33 
                 deflection roll 
               
               
                 34 
                 deflection roll 
               
               
                 35 
                 laser beam device 
               
               
                 36 
                 frame 
               
               
                 37 
                 Arrow (to illustrate the direction of adjustment) 
               
               
                 38 
                 collection bin 
               
               
                 39 
                 laser beam 
               
               
                 40 
                 suction nozzle 
               
               
                 41 
                 suction nozzle 
               
               
                 42 
                 sheet 
               
               
                 43 
                 sheet 
               
               
                 44 
                 recess 
               
               
                 45 
                 recess 
               
               
                 α 
                 angle 
               
               
                 β 1 , β 2   
                 angle 
               
               
                 y 
                 lateral direction 
               
               
                 z 
                 travel direction

Technology Category: 7