Abstract:
A bottomer for the production of sacks, preferably cross-bottom valve sacks, includes at least one glue unit that applies glue to the components of the sacks. The glue unit includes a nozzle bar, which has at least one nozzle for extruding glue onto the sack components. The glue unit also includes a counter support, which positions the sack components with a force against the nozzle bar.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a national stage of PCT/EP08/066,260 filed Nov. 26, 2008 and published in German, which has a priority of German no. 10 2007 057 820.4 filed Nov. 30, 2007, hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to a bottomer for the production of sacks, a glue unit for applying glue to flat objects, and a method for the production of sacks. 
     2. Description of the Prior Art 
     Bottomers have been disclosed in the prior art. In particular, the production of cross-bottom valve sacks, which have been known for a long time, is the object of numerous published prior-art documents (e.g., DE 710 264 or DE 746 334) and is carried out using so-called bottomers or bottoming machines. 
     Also the application of glue to components of the sacks during production has been known for a long time from the published prior art (e.g., DE 090 145 48 U1 and DE 30 200 43 A1). 
     Traditional glue units use rollers, which usually support a plate in order to apply glue to the sack components. In cross bottomers, glue is often applied to the folded bottoms of the sacks, cap strips and valve patches assigned to the bottoms. 
     Devices have been disclosed in the recent past, which apply glue to sack components with the aid of nozzles. These nozzles are attached to a nozzle head or a nozzle bar or inserted into the latter in the form of bores. DE 103 09 893 A1 discloses a device of such type. 
     Devices of the aforementioned type offer a number of advantages. Thus, the plurality of different plates required to be kept ready for the production of different sack formats is rendered redundant. 
     However, there continues to be a need for improvement when it comes to ensuring a uniform and continuous application of glue to the sack components. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to suggest a device and a method by means of which the glue application is more uniform and more continuous. 
     The present invention is therefore based on the teaching of DE 103 09 893 A1 and achieves the object by adding the inventive features described herein. 
     It has been observed that a counter support, which positions the sack components with a force against the nozzle bar, results in the starch glue commonly used in the production of sacks being entrained or stripped off uniformly from the sack components when the sack component in question moves past the nozzle bar at a relative speed. 
     This holds true particularly in the application of cold glue. 
     This movement (at the relative speed mentioned above) is usually a movement of the sack components past a stationary nozzle bar, as already suggested in the document DE 103 09 893 A1 cited above. The nozzle bar in question can have or support any number of nozzles. The presence of more than two nozzles is of particular interest here. However, embodiments having more than five nozzles are also advantageous. More than ten nozzles are used advantageously in connection with the application of glue to cross-bottoms. In bottomers, such glue units of a new design can be used to apply glue to folded bottoms of sacks and/or bottom cap strips and/or valve patches. 
     It should be mentioned that a person skilled in the art usually differentiates between bags and sacks. However, the term “sacks” is intended to mean bags and/or sacks in the present wording of the claims. 
     As already mentioned above, the sack components are positioned by a counter support with a force against the nozzles. In doing so, it is advantageous if the counter support is made, at least partly, of flexible material. The flexibility of the counter-support material ensures that the sack-component surface requiring glue application, which sack components are made of several layers of material of various sizes and overlaps, is pressed against the nozzle bar. In addition to or instead of the flexibility, which at least ensures that the sack components are not crushed by an extremely rigid counter support, springy elements can also be inserted into the counter support. In addition to the softness of the flexible parts, the springy elements apply more restoring force. The elastic materials used can be elastomers. Spring steel sheets are cited as an example of springy materials. 
     It is advantageous 
     if the counter support comprises an active surface, and 
     if force can be applied with the aid of this active surface to at least one part of the rear side of the sack-component surface requiring glue application while the sack component is passing through the glue unit. 
     With the aid of such an active surface, the force required for positioning the sack components can be transmitted uniformly and optionally extensively to the sack components. The transmission of force to the rear side of the surface requiring glue application offers additional advantages. 
     It has proved to be advantageous to provide the active surface with a segmented design. This is particularly advantageous if the surfaces requiring glue application have varying thickness. This can result from different numbers of paper or foil layers. In this context, the term “segmented” means that the active surface is divided into partial areas. The partial areas can transmit force independently of each other to the rear side of the sack components. These partial areas can therefore also be moved independently of each other. 
     These partial areas can be circular, rectangular or oval and can virtually act as punches against the rear side of the sack components. The length of the partial areas (extension in the direction of movement of the sack components relative to the nozzle bar) can be proportionate to the width (extension transverse to the transfer direction). Ratios of width to length that are greater than 1:4 are advantageous. 
     The use of belts, whose surface components oriented toward the sack components form the active surface, is particularly advantageous. This is due to the elasticity of the belts, among other things. The segmentation of the active surface composed of several stretched belts results automatically when using a plurality of belts. The belts are usually stretched parallel to each other. It has proved to be advantageous if the belts are oriented along the direction of the relative movement of the sack components in the glue unit. In most cases, the nozzle bar extends transversely to the transfer direction of the sack components. In this case, approximately punctiform regions result, in which the belt deflected by the force action of the nozzle bar in the direction of the active surface presses the rear side of the sack components with a force. 
     It is also advantageous if the belts are not supported by a roller in this immediate area of influence of the nozzle bar. The use of various elastic belts at this location is possible. The belts can also be hinged to the counter support such that the former can move. A movability with the same orientation and optionally the same algebraic sign as the relative movement between the sack components and the nozzle bar is also of advantage here. The term “movability” in the aforementioned sense means that the belts and the active surface defined by them are movable relative to the machine frame. Usually, such a movability is brought about by guiding such belts over guide rollers. Endless belts are advantageous in this connection. It is possible to set the movable belts in motion by means of the movement of the sack components relative to the glue unit. The sack components are usually guided through the machine with the aid of other transport means such as conveyor belts (could also be grippers or the like), and driving forces could thus be transmitted to the belts of the counter support in question. 
     However, in this case, the sack components in question would be exposed to defined transmitted forces (particularly disadvantageous shearing forces). 
     It is therefore advantageous to drive the belts, with the drive device being preferably aligned with the direction and/or speed of the transport movement of the sacks in the glue unit. 
     It is advantageous to hinge the counter support and/or the nozzle bar to the machine frame in such a way that the entry angle of the sack components to the nozzle bar can be changed. Usually, the active surface is deviated relative to the machine frame for this purpose; that is, the components supporting or defining the active surface are hinged to the machine frame such that they can pivot. Summing up, it should be mentioned that the term “pivotability” is to be understood to mean the movability of the counter support, which movability changes the entry angle of the sack components into the gap between the counter support and the nozzle bar. In any case, the provision of such a pivotability of the position of the counter support relative to the nozzle bar is advantageous. Alternately and additionally, a linear movability of the counter support relative to the nozzle head is advantageous. This can be achieved by means of a movability of the nozzle head relative to the machine frame. However, here too, an additional linear movability of the counter support relative to the nozzle bar is alternately and additionally of advantage. 
     The contact pressure of the sack components can thus be adjusted with the aid of this movability, and it is possible, inter alia, to address the varying thickness of the sack components. 
     An additional advantageous embodiment of the invention has holding means, which transmit a holding force to the sack components. This holding force is advantageously transmitted to that side of the sack components to which glue is applied in the corresponding glue unit. A clamping effect can thus be achieved when the force of the counter support acting in the direction of the nozzle bar and the force of the holding means counteract each other. It is advantageous if the holding force acts on discrete closed surface regions of the sack components. These can be at a distance from each other in the spatial direction (x) extending transversely to the relative movement of the sack components. In the latter case, an adjustability of this distance is of advantage. The holding means can be designed as grippers, punches or also guide belts. 
     Additional exemplary embodiments of the invention will become apparent from the following description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the individual figures: 
         FIG. 1  is a sketch of a first exemplary embodiment of a glue unit of the invention 
         FIG. 2  is a view of the counter support (roller) shown in  FIG. 1   
         FIG. 3  is a sketch of a second exemplary embodiment of a glue unit of the invention 
         FIG. 4  is a top view of the active surface of the counter support of the glue unit shown in  FIG. 3   
         FIG. 5  is a top view of an active surface of the counter support of an additional glue unit shown in  FIG. 6   
         FIG. 6  is a sketch of a third exemplary embodiment of a glue unit of the invention 
         FIG. 7  shows the bottom of a cross-bottom valve sack 
         FIG. 8  shows the counter support of a glue unit for patches 
         FIG. 9  shows the counter support shown in  FIG. 8  during the transport of a patch 
         FIG. 10  is another view of the counter support shown in  FIG. 8   
         FIG. 11  is a top view of the counter support of an additional glue unit 
         FIG. 12  is a top view of the counter support of an additional glue unit 
     
    
    
     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. 
       FIG. 1  shows a sketch of a first exemplary embodiment of a glue unit  1  of the invention, to which sack components  2  are supplied in the transfer direction z. A significant component of the glue unit  1  is the application head  3  comprising the nozzle bar  4 , which mechanically counteracts the counter support  5 . The counter support  5  is designed as a rotating roller, whose active surface  6  that is in contact with the rear side  7  of the sack component  2  and that transmits to the latter  2  the force required for being positioned against the nozzle bar is wiped off during each revolution of the counter support  5  by the doctor-blade device  8  comprising the doctor blade  9 . 
       FIG. 2  shows another view of the counter support  5  shown in  FIG. 1 , which shows that the active surface  6  is divided by means of slots  10  into surface segments  11 . This division enables better positioning of the sack components having surfaces that are structured and have a characteristic topography with significant differences in height. 
     The counter support  5  designed as a roller has pins  13 , on which it 5 can be mounted. 
       FIG. 3  shows another exemplary embodiment of a glue unit of the invention, which likewise comprises an application head  3  comprising a nozzle bar  4 , with the aid of which glue can be applied to the sack components  2 . The angle α is the angle, in which the sack components enter into the glue-application gap  12  formed by the nozzle bar  4  and the counter support  5 . The counter support  5  is represented in a conventional form in  FIG. 3  and can be implemented in the form shown in  FIGS. 4 ,  5 ,  6  and  11 . 
     In  FIG. 4 , the belts  14  are the elements defining the active surface  6  of the counter support  5 . Those surface components of the belts  14  that come into contact with the sack components  2  when the latter are guided over the belts  14  form the active surface  6  in this case. The belts can be guitar strings that are oriented largely parallel to each other as shown in  FIG. 4  and are under a defined (low) mechanical stress. The guitar strings or belts  14  are hinged to the legs  15 . In this embodiment, it is also advantageous to align the belts along the direction of travel of the sack components. 
     The active surface  6  formed by the belts  14  is already segmented since the belts are at a distance from each other. 
       FIG. 6  shows another glue unit comprising another counter support  5 , which in turn comprises belts  14 , whose surface components touching the sack components  2  form the active surface  6 . Unlike the exemplary embodiment shown in  FIG. 4 , the belts are guided by guide rollers  16  and moved in the transfer direction z of the sack components  2 . The belts guided in such a way are again wiped off by the doctor-blade device  8  comprising the doctor blade  9 . 
       FIG. 5  shows the active surface  6  from the point of view of the application head  3 , which active surface is formed by the belts  14  running on the guide rollers  16 . 
       FIG. 7  shows the bottom  17  of a cross-bottom valve sack  18 . The illustration is intended to clarify that the folding and material edges of such a sack bottom have differences in height. In view of these differences in height, the application of the counter supports  5  illustrated is of particular advantage here. 
       FIG. 8  shows a counter support  5  that is substantially made of one roller. This roller has a segmented active surface  6  that is divided by means of slots  10  into surface segments  11 . The surface segments are made of an elastic material that covers the circumferential surface of the roller serving as the counter support  5 . 
     The roller comprises a clamping strip  19  that can fix a sack component—particularly, a patch—on the roller surface. The possible clamping movement of the clamping strip  19  is denoted by the arrow  21  in  FIG. 10 .  FIG. 9  shows the manner in which a patch  20  is transported on the active surface  6  of the counter support  5 . 
       FIG. 11  shows, from the point of view of the nozzle head  3 , an additional active surface  6  comprising surface segments  11  delimited by the slots  10 . The surface segments  11  oriented toward the sack components  2  are flexible. The surface segments themselves are positioned against the sack component by spring elements disposed on that side of the surface segments that is oriented away from the sack components. A point-elastic positioning of the sack components against the nozzle bar  4  is also achieved in this way. In reference to the different active surfaces  6  composed of surface components of belts  14 , it must be mentioned that the point elasticity comes into being particularly when the belts  14  are oriented transversely to a linear nozzle bar  4 . 
       FIG. 12  suggests another possibility of guiding the sack components  2  in a glue unit  1 . To begin with, a counter support  5  largely corresponding to the counter support  5  shown in  FIGS. 5 and 6  is illustrated from the point of view of the application head  3 . Furthermore, the belts  21  are shown that are located in front of the belts  14  of the counter support from the point of view of the nozzle head. During transportation through the glue unit  1 , the sack components  2  are fixed between the belts  14  and  21 . Both types of belts are movable in the transfer direction so that the sack components are entrained between the largely synchronized belts. The belts  21  are shiftable in terms of their position in the direction x extending transversely to the transfer direction z of the sack components  1 . This shiftability is ensured with the aid of measures that constitute standard practice such as shiftable suspension means of the rollers guiding the belts. 
     It is advantageous to adjust the distance of the belts  21  from each other such that the belts grasp the transported sack components in their end regions in the x direction. 
     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 signs 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  1 
                 First glue unit 
               
               
                  2 
                 Sack components 
               
               
                  3 
                 Application head 
               
               
                  4 
                 Nozzle bar 
               
               
                  5 
                 Counter support 
               
               
                  6 
                 Active surface of the counter support 5 
               
               
                  7 
                 Rear side of the sack components 2 
               
               
                  8 
                 Doctor-blade device 
               
               
                  9 
                 Doctor blade 
               
               
                 10 
                 Slots 
               
               
                 11 
                 Surface segments 
               
               
                 12 
                 Glue-application gap 
               
               
                 13 
                 Pin of the counter support 5 
               
               
                 14 
                 Belts of the counter support 5 
               
               
                 15 
                 Legs to which the belts 14 are hinged 
               
               
                 16 
                 Guide rollers 
               
               
                 17 
                 Sack bottom 
               
               
                 18 
                 Cross-bottom valve sack 
               
               
                 19 
                 Clamping strip 
               
               
                 20 
                 Patch 
               
               
                 21 
                 Belts 
               
               
                 22 
                 Arrow 
               
               
                 23 
                 End region in x-direction 
               
               
                 L 
                 Length of the surface segment 11 
               
               
                 B 
                 Width of the surface segment 11 
               
               
                 z 
                 Transfer direction of the sack component 2 
               
               
                 x 
                 Direction extending transversely to the transfer direction z 
               
               
                 α 
                 Entry angle