Abstract:
A method of severing a band ( 11 ) which encloses a blank stack ( 10 ), wherein the band ( 11 ), preferably in the region of a band station ( 19 ), is severed by a cutting means, in particular a knife ( 23 ), and is then removed from the blank stack ( 10 ). According to the invention, it is provided that the blank stack ( 10 ) is pushed together such that the band ( 11 ) is spaced apart from the blank stack ( 10 ), at least in certain regions, and that the band ( 11 ) is then severed in the spaced-apart region by the cutting means. The invention also relates to a corresponding apparatus for implementing the method.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a method of severing a band which encloses a blank stack, wherein the band, preferably in the region of a band station, is severed by a cutting means, in particular a knife, and is then removed from the blank stack. The invention also relates to a corresponding apparatus, in particular for implementing the aforementioned method, for severing a band which encloses a blank stack, having a band station in which the blank stack rests on its underside on an underlying surface, in particular a platform, and in which the band can be severed by a cutting means, in particular a knife. 
     2. Prior Art 
     Blanks for producing packs made of (thin) cardboard, in particular for producing hinge-lid boxes (hinge-lid packs) for cigarettes, are prefabricated, usually in a cardboard-box factory and supplied as a blank stack. In order to safeguard the formation of the blank stack, it is often common practice to provide the blank stack with a strip-like enclosing band made of paper, foil or the like. In the region of the packaging machine, the band then has to be severed and disposed of, in order for it to be possible for the band-free blank stack to be transferred to the packaging machine, in particular to a blank magazine of the same, for further processing. 
     A method and an apparatus of the type mentioned in the introduction are known, for example, from the applicant&#39;s EP 0 706 946 B1 and have proven successful, in principle, in practice. 
     BRIEF SUMMARY OF THE INVENTION 
     Proceeding herefrom, it is an object of the invention to develop the method and apparatus of the type mentioned in the introduction further, in particular in respect of making it possible for the bands to be opened in a manner which safeguards the blanks to a greater (or even greater) extent. 
     This object is achieved by a method of severing a band which encloses a blank stack, wherein the band, preferably in the region of a band station, is severed by a cutting means, in particular a knife, and is then removed from the blank stack, characterized in that the blank stack is pushed together such that the band is spaced apart from the blank stack, at least in certain regions, and in that the band is then severed in the spaced-apart region by the cutting means. 
     Accordingly, it is provided that the blank stack is pushed together such that the band is spaced apart from the blank stack, at least in certain regions, and that the band is then severed in the spaced-apart region by the cutting means. In contrast to EP 0 706 946 B1, the blank stack is thus not pushed together in order to spread apart the blanks in the stack so that a knife can penetrate into the blank stack and sever the band (column 4, lines 22 to 42); rather, the entire blank stack is pushed together so that the band is exposed and can be severed to the side of the blank stack. This makes it possible to avoid any possible damage to the blanks by contact with the cutting means as the band is being severed. 
     In a preferred configuration of the method according to the invention, it is provided that the band, at least during the operation of the blank stack being pushed together, is retained in certain regions and/or is brought into abutment against at least one side surface of the blank stack such that the band, by virtue of the blank stack being pushed together, is spaced apart from the blank stack in a non-retained region, or in a region which does not butt against the at least one side surface of the blank stack, and is severed there by way of the cutting means. The term “retained” should be understood to the effect that the position of the band is changed only insignificantly, if at all, in this region by virtue of the blank stack being pushed together and thus compressed in the process. This then results in the band being spaced apart in the other regions. 
     This can preferably take place such that the blank stack, during the pushing-together operation, butts partially, in the region of a side surface, against an abutment wall, wherein the abutment wall has smaller dimensions, in particular a lower height, than the corresponding side surface of the blank stack such that the band, by virtue of the blank stack being pushed together, is spaced apart from the blank stack in that region of the side surface of the latter that does not butt against the abutment wall, and is severed there by way of the cutting means. This makes it possible to create the position of the spaced-apart region in a specific manner so that the knife can be moved always in a predetermined, constant cutting plane. 
     According to a preferred development, it is provided that the abutment wall, preferably as the blank stack is being pushed together, is moved by the ram plate into a correct position relative to a side surface, in particular the upper side, of the blank stack such that the abutment wall, irrespective of the dimensioning, in particular height, of the blank stack in each case, does not cover a preferably essentially constant-height portion of the side wall of the blank stack. This means that the band, irrespective of the height of the blank stack, can be spaced apart from the blank stack at a suitable location in order to ensure that the severing cut is always carried out correctly. 
     The pressure is applied to the blank stack preferably in that the blank stack in the band station rests on an underlying surface, in particular a platform, and the band is spaced apart from the blank stack by virtue of pressure being applied, in particular by means of a ram plate, to a side surface, in particular an underside and/or upper side, of this blank stack. It should be emphasized that preferably the entire blank stack is compressed, for example by virtue of being pushed together in the vertical direction. 
     The direction in which the pressure is applied to the stack can depend, in the first instance, on the dimensions of the blanks and, in addition, on whether the stack is in a standing or lying position. In the preferred exemplary embodiment, the stack stands upright and the blanks are located in a flat (horizontally oriented) state one above the other within the stack, so that the pressure is directed transversely to the upper side and/or underside of the blanks. Correspondingly, it is possible, in the case of a stack in a lying position in which the blanks stand upright one beside the other, for the pressure to be applied laterally to the stack, that is to say, once again, transversely to the vertically oriented large-surface-area upper sides and/or undersides of the blanks. 
     It is further conceivable for the pressure to be applied essentially parallel to the upper side and/or underside of the blank. This gives rise to the blanks being deformed in a curved manner, as a result of which the band is spaced apart from the stack, and can be severed, at one end of the stack. It is conceivable, for example in the case of a stack in a standing position according to the exemplary embodiment, for lateral pressure to be applied to the blanks such that the latter curve upward approximately in the longitudinal center, so that the severing cut can be carried out in the region of the underside of the blank stack. 
     The operation of severing the band in the region spaced apart from the blank stack is preferably carried out at a (lateral) distance from the blank stack, or the contour of the blank stack, such that the cutting means does not penetrate into the blank stack to prevent the blanks from being damaged by the cutting means. 
     The severed band is removed from the blank stack preferably in that in the first instance a crosspiece of the band is pulled off from the blank stack in the region of a side surface, in particular of the upper side, in particular by being raised, preferably by means of a suction mechanism, and in that thereafter the blank stack is conveyed away out of the band station, wherein the band is pulled off from the blank stack in particular by a pulling mechanism. 
     Further advantageous configurations of the method according to the invention can also be gathered from the dependent claims and the description. 
     An apparatus which achieves the object mentioned in the introduction is an apparatus for severing a band which encloses a blank stack, having a band station in which the blank stack rests on its underside on an underlying surface, in particular a platform, and in which the band can be severed by a cutting means, in particular a knife, characterized in that the blank stack, for the purpose of spacing the band apart from the blank stack at least in certain regions, can be pushed together, in particular by means of a ram plate, such that the band can be severed in the spaced-apart region by way of the cutting means. 
     Accordingly, it is provided that the blank stack, for the purpose of spacing the band apart from the blank stack at least in certain regions, can be pushed together, in particular by means of a ram plate, such that the band can be severed in the spaced-apart region by way of the cutting means. This gives rise to the advantages mentioned in the introduction. 
     Preferred developments in respect of the adjustment of an abutment wall can be gathered from the dependent claims. 
     A special feature, furthermore, may be constituted by the fact that the knife is oriented in a plane which is directed obliquely in relation to the side surfaces of the blank stack and of the band, and that a cutting edge of the knife is directed away from the blank stack such that, as the band is being severed, a tensile force which is directed away from the blank stack can be applied to the band. This means that the band is held taut as the severing cut is being carried out. 
     Further advantageous configurations of the apparatus according to the invention can also be gathered from the dependent claims and the description. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       A preferred exemplary embodiment of the invention will be explained hereinbelow with reference to the drawing, in which: 
         FIG. 1  shows a side view of an apparatus for removing bands, 
         FIG. 2  shows the apparatus according to  FIG. 1  as the band is being severed, 
         FIG. 3  shows the apparatus according to  FIG. 1  as the band is being pulled off, 
         FIG. 4  shows the apparatus according to  FIG. 1  as the blank stack is being pushed off, and 
         FIGS. 5 and 6  show a side view of the apparatus as seen in arrow direction V in  FIG. 2  at different points in time during the operation of severing the band. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The exemplary embodiments in the drawings concern the handling of stacks  10  of blanks for the cigarette industry, these blanks being elongate ones with the contour which is typical of those for the production of hinge-lid boxes (hinge-lid packs). The blanks consist of thin cardboard. Within the blank stack  10 , the blanks are located in a flat state one above the other, wherein side peripheries of the blanks are oriented such that the blank stack  10  has linear side peripheries. 
     Each blank stack  10  is enclosed by a strip-like band  11 . The latter is designed as a finite, rectangular tubular piece with mutually opposite upright legs  12 ,  13  and upper and lower crosspieces  14 ,  15 . The band  11  is formed from a finite material strip with an adhesively bonded overlap in the region of the leg  13 . The band  11  consists preferably of paper, but may also consist of a foil or some other suitable material. 
     The blank stacks  10  provided with such a band  11  are supplied, for example, on a pallet (not shown). A suitable lifting conveyor, e.g. a robot with a lifting head, sets the blank stacks  10  down individually or in groups, to form a continuous row, on a feed conveyor. The latter may be designed as a belt conveyor in accordance with EP 0 706 946 B1. The feed conveyor can convey the blank stacks  10  one after the other into a band station  19 . In the region of the latter, the band  11  is severed and disposed of. The blank stacks  10  which have been freed of the band  11  are then transferred to a removal conveyor, which feeds the blank stacks  10  for further processing. The band station  19  may be, for example, part of a packaging machine for producing hinge-lid boxes for cigarettes. As in the case of EP 0 706 946 B1, the feed conveyor and band station  19  may be positioned in the region of the rear side of the packaging machine. 
     In the band station  19 , the blank stack  10  is conveyed by the feed conveyor onto an underlying surface, namely onto a platform  21 . The blank stack  10  rests on the latter during the operation of the band  11  being severed. 
     A cutting arrangement  22  which can be moved up and down is positioned above the platform  21  and/or the blank stack  10 . This cutting arrangement is provided with a knife  23  as the cutting means for severing the band  11 . For this purpose, the blade-like knife  23  is moved in a horizontal plane relative to the blank stack  10  and/or to the band  11  ( FIGS. 5 and 6 ). 
     For this purpose, the knife  23  is fitted on a knife holder  24 , which can be moved back and forth and can be displaced in the manner of a carriage on a guide rail  25  of the cutting arrangement  22 . The elongate knife  23 , or a cutting edge  26  of the same, is directed away obliquely from the blank stack  10 , so that the band  11  is automatically held taut as the severing cut is being carried out. 
     In order for the severing cut to be carried out, the knife holder  24  is displaced along the guide rail  25 . The knife  23  here is guided laterally alongside the blanks, in the first instance outside the region of the band  11 , until the upright leg  12  is gripped and severed. This operation is assisted by a guide pin  28 , which is formed in front of the cutting edge  26  of the knife  23  ( FIG. 5 ). During the cutting movement, the knife  23  slides to the end of the blank stack  10 . 
     In order for a cutting operation to be carried out, the cutting arrangement  22  can be lowered into the cutting plane by a lifting cylinder  27 . Prior to the band  11  being severed, pressure is applied to the blank stack  10  from above by an elongate, strip-like ram plate  29 . The latter is lowered onto the blank stack  10  from above, along with the cutting arrangement  22 , and is subjected to the action of the lifting cylinder. Together with the cutting arrangement  22 , furthermore, a suction mechanism  30  is lowered onto the blank stack  10  from above, this mechanism, in the present case, being arranged in the region of the underside of the ram plate  29  and serving for gripping the crosspiece  14  of the band  11 . 
     The blank stack  10  is subjected to pressure by the ram plate  29  such that the entire blank stack  10  is pushed together, which means that the band  11 , rather than continuing to enclose the blank stack  10  tightly, is loosened. This then gives rise to the formation of in particular loop-like regions in which the band  11  is spaced apart from the blank stack  10 , that is to say runs at a distance from the contour of the blank stack  10 . This is exploited in order for the severing cut to be carried out in these regions. It is possible here for the knife  23 , or the cutting edge  26 , to be guided laterally alongside the blank stack  10 , so that there is no risk of the blank stack  10  being damaged by the knife  23 . 
     Once the severing cut has been carried out, the knife  23  is moved back, by way of the knife holder  24 , into the starting position and the cutting arrangement  22  is moved into the upper, starting position according to  FIG. 1 . The severed band  11  is then disposed of. For this purpose, the band  11  is gripped in the region of the leg  12  by a holder. The latter, in the present case, is assigned to an abutment wall  31  which, in the starting position, serves at the same time for positioning the blank stack  10  precisely on the platform  21 . The blank stack  10  butts against the abutment wall  31  by way of the leg  12  of the band  11  ( FIG. 1 ). 
     However, rather than being used just for removing the band  11  and for positioning the blank stack  10 , the abutment wall  31  also assists in carrying out the severing cut. As is evident from  FIG. 1 , the abutment wall  31  terminates at a distance beneath the upper side of the blank stack  10 . Since the blank stack  10  butts against the abutment wall  31  by way of the leg  12 , the band  11  can form a loop only in the region above the abutment wall  31 , since the ram plate  29  also extends approximately into the plane of the abutment wall  31 . This means that the arrangement of the abutment wall  31  predetermines the region in which the band  11  is spaced apart from the blank stack  10 . As a result, the severing cut can be carried out always in the same plane. 
     A further special feature is constituted by the fact that the position of the abutment wall  31  can be adapted to the height of the blank stack  10 . For this purpose, the abutment wall  31  is moved in the first instance into an upper position according to  FIG. 1 . In this position, the abutment wall  31 , depending on the height of the blank stack  10 , can also project beyond the latter. As the cutting arrangement  22  is lowered, the position of the abutment wall  31  is then adapted in a vertical direction. A pusher  33  is provided for this purpose, this pusher being fixed on the cutting arrangement  22  and projecting in relation to the underside of the ram plate  29 . The pusher  33  is positioned such that, as the cutting arrangement  22  is being lowered, it moves the abutment wall  31  downward in the vertical direction. In the present exemplary embodiment, this is achieved in that the pusher  33 , as the cutting arrangement  22  is being lowered, pushes against the upper side of the abutment wall  31  and moves the latter correspondingly downward. This results in the upper periphery of the abutment wall  31  being spaced apart from the plane of the underside of the ram plate  29  to a defined extent corresponding to the extent by which the pusher  33  projects in relation to the underside of the ram plate  29 , irrespective of the height of the blank stack  10 . 
     The lower end position of the abutment wall  31  and of the ram plate  29  is predetermined, in the present case, by the blank stack  10 . As soon as it is no longer possible for the latter to be pushed together any further, the lifting cylinder is switched off and the severing cut is carried out. This makes it possible for blank stacks  10  of different heights to be processed in the apparatus. 
     The abutment wall  31 , furthermore, is provided with retaining mechanisms for gripping the band  11  following the severing operation. These retaining mechanisms are in the form of a plurality of suction mechanisms  32  arranged one beside the other. These are positioned on the abutment wall  31  such that they grip the severed leg  12  in the upper region. For this purpose, the abutment wall  31  may be mounted by way of sliding guides, in a manner analogous to EP 0 706 946 B1, on two spaced-apart, upright guide rods  34 . The abutment wall  31  can be moved up and down by a linear cylinder  37 . 
     By virtue of the abutment wall  31  being moved downward out of the upper position according to  FIGS. 1 and 2  into the lower position according to  FIGS. 3 and 4 , the leg  12  of the band  11 , this leg being retained by the suction mechanisms  32 , is moved downward as well. Since the blank stack  10  rests on the remainder of the band  11 , namely on the lower crosspiece  15 , without undergoing any changes, the leg  12  in the first instance forms a loop ( FIG. 3 ). 
     The blank stack  10  is then moved out of the band station  19  ( FIG. 4 ), wherein the severed band  11  is held back and conveyed away. The blank stack  10  passes, without its band  11 , onto a removal conveyor. In the present case, the blank stack  10  is pushed out of the platform  21  directly onto a platform  39  of a vertical conveyor  40 . The platform which has one side mounted on this vertical conveyor  40  extends level with the platform  21  as it receives the blank stack  10 . The blank stack  10  is transferred from the platform  21  onto the vertical conveyor  40  by a pusher unit  41 , which may be designed in accordance with EP 0 706 946 B1. 
     Further pulling mechanisms take effect in order to remove the severed band  11  altogether in the downward direction, these pulling mechanisms being formed by a pair of pulling rollers comprising a first, fixed-location pulling roller  49  and a second, pivotable abutment roller  50 . The latter is arranged in a pivotable manner on the abutment wall  31 , above the suction mechanisms  32 . The band  11 , or the leg  12  thereof, butts against the pulling roller  49  following the severing operation. By virtue of being pivoted into the position according to  FIG. 4 , the abutment roller  50  moves against the pulling roller  49 . The abutment roller  50  here passes through a through-passage in the abutment wall  31 . The pair of rollers  49 / 50  then act together to convey the entire band  11  in the downward direction. It is preferably provided that the pulling roller  49  and the abutment roller  50  are driven in rotation exclusively during the period of time which is shown in  FIG. 4 , and are at a standstill for the rest of the time. The band  11 , which finally is pulled all the way off from the blank stack  10 , passes, via a directing plate  52 , into a collecting container (not shown) beneath the platform  21 . 
     LIST OF DESIGNATIONS 
     
         
           10  Blank stack 
           11  Band 
           12  Leg 
           13  Leg 
           14  Crosspiece 
           15  Crosspiece 
           19  Band station 
           21  Platform 
           22  Cutting arrangement 
           23  Knife 
           24  Knife holder 
           25  Guide rail 
           26  Cutting edge 
           27  Lifting cylinder 
           28  Guide pin 
           29  Ram plate 
           30  Suction mechanism 
           31  Abutment wall 
           32  Suction mechanism 
           33  Pusher 
           34  Guide rod 
           37  Linear cylinder 
           39  Platform 
           40  Vertical conveyor 
           41  Pusher unit 
           49  Pulling roller 
           50  Abutment roller 
           52  Directing plate