Abstract:
The invention relates to a method and device for unpacking a stack of products packaged in a sleeve, such as a stack of covers for cans, for instance drink cans, having the steps of removing a portion of the sleeve located on a longitudinal end; peeling away the sleeve over the stack with a relative movement of the stack and the sleeve; and separately discharging the stack without the sleeve.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and a device for unpacking a stack of products packaged in a sleeve, such as a stack of covers for cans, for instance drinks cans. 
     2. Description of the Related Art 
     In the production of drinks cans the body of the can is usually punched, while after filling with the contents the cover is arranged in the filling opening for filling of the drinks can and is fixed there. For this purpose the covers are supplied in stacks which are packed per stack in a sleeve, for instance of paper. It is noted that the present invention is not limited to stacks of covers for drinks cans, but is applicable in the unpacking of all types of products packed in a sleeve which are stacked in the sleeve. 
     It is generally known to manually remove the sleeve from the stack of products. For this purpose a longitudinal cut, either linear or helical, is made in the packaging-like sleeve. The stack is then removed from the packaging and placed on a conveyor belt for further processing. This manual work is time-consuming and cannot usually be performed rapidly enough to keep up with the devices which process the products. In addition, the work is stultifying and can easily lead to mistakes, wherein the stack of products is set down the wrong way round and then presented the wrong way round to the device for further processing of the products, which can hereby jam. 
     Automated solutions are known, which are however all based on cutting through the sleeve in axial direction—linearly or helically—wherein the sleeves with the stacks of products therein must often still be placed manually in the automated unpacking device, which can still result in problems with the orientation of the products in respect of the devices for further processing. 
     EP-A-0,947,428 relates to a technique of longitudinally cutting the sleeve before discharge of the stacks of products, where the stacks and the associated sleeve are generally relatively long, for which purpose machines have to be used which must have a freedom of movement over correspondingly long distances. Such packaging devices hereby become complex and costly. Damage to the sides of the products can moreover occur with the longitudinal cutting movement in both manual unpacking processes and automated unpacking processes. This is a particular drawback in the case of for instance drinks cans, since it is then not possible to ensure that the finally assembled drinks cans are also made watertight. Damage resulting from the cutting of the sleeve is of course also undesirable in the case of other stacks of products packed in sleeves, precisely because the sleeve itself already serves to protect the stacks of products. 
     It is acknowledged that from U.S. Pat. No. 4,852,253 a technique is known for automatically unpacking relatively short stacks of coins wrapped in a wrapper. 
     SUMMARY OF THE INVENTION 
     The present invention has for its object to obviate the drawbacks of the above described known art, for which purpose a method and a device are provided, which are distinguished respectively by removing and means for removing a part of the sleeve located on a longitudinal end, peeling away the sleeve over the stack with an opposed relative movement of the stack and the sleeve and means for this purpose, and separately discharging the stack and means for this purpose. 
     Since only the part of the sleeve located at the longitudinal end is removed, the danger of damaging a whole stack of products is obviated. The unpacking process is considerably simplified and automation thereof made appreciably easier in accordance herewith, without exceptionally complex and costly equipment having to be employed for this purpose. 
     In a preferred embodiment the sleeve is tensioned over the stack on the longitudinal end and a cut is then made in the sleeve at that location. This ensures that the whole or partial removal of the portion of the sleeve located on the longitudinal end takes place accurately, particularly when the sleeve is arranged slightly loosely round the stack of products, as is the case with a paper sleeve. Tensioning of the sleeve can comprise of fixing the sleeve and pushing the stack of products in the fixed sleeve up against the longitudinal end of the sleeve. Use can be made for this purpose of for instance a hydraulic or pneumatic cylinder which presses against the end of the sleeve situated opposite the longitudinal end while the sleeve itself is fixed. This is particularly simple to realize. 
     The portion of the sleeve located on the longitudinal end can further be wholly or partly removed by perforating the sleeve wholly or partly around the longitudinal end thereof and further relying on pressing of the stack of products out of the sleeve during the relative movement of the stack and the sleeve. This can take place by arranging notches in the sleeve, which is extremely simple to realize, particularly when the sleeve is for instance manufactured from paper. When the products have a form corresponding with the pattern of notches, a safety can be provided which checks alignment of the notch and the recesses before the notches are arranged, and arranging of the notches takes place only when the alignment is correct. A safety is thus provided to prevent the possibility of the stack of products in the sleeve being unpacked the wrong way round and passed on to further processing equipment, with the purpose of preventing disruptions therein. The sleeve can further be fixed and the stack pressed through the radial pattern of notches by pushing up the stack in order to remove the portion on the longitudinal end of the sleeve. The number of cutting operations can hereby be minimized and limited to a minimal depth, whereby further damage to the products can be prevented with certainty. In the interim period between pushing up against the longitudinal end of the sleeve and pushing up through the longitudinal end the sleeve can be released for movement and be displaced in the direction of the end of the sleeve situated opposite the longitudinal end. The movement distance of all moving parts involved in fixing of the sleeve and pushing the stack up to and through the longitudinal end of the sleeve is hereby minimized, for which purpose machines with a small stroke can be used which are simple and relatively inexpensive. 
     Another embodiment will further be discussed hereinbelow for peeling away the sleeve over the stack of products. A part of the sleeve extending beyond the stack of products is herein engaged with a set of rotatable wheels which can be moved away from and toward each other. When the wheels engage the protruding part of the sleeve, they are driven in rotation in an opposing direction. The sleeve is hereby peeled from the roll of products. The wheels are of course then arranged on the opposite end of the sleeve opposite the removed longitudinal end such that the sleeve is peeled away from the stack by retraction between the wheels. In order to prevent the sleeve being crumpled, the wheels can be intermittently moved respectively away from and toward each other during driving thereof. This ensures that a movement of the sleeve being peeled away is always guaranteed in axial direction of the stack. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment, to which the invention is not limited, will be described hereinbelow with reference to the annexed figures, in which: 
     FIG. 1 shows a schematic perspective view of a device for realizing the method, both according to the present invention; 
     FIG. 2 shows in enlarged view a detail of the device depicted in FIG. 1; and 
     FIGS. 3-11 show schematic views of the sequence of operations carried out in an embodiment of the method and by an embodiment of the device according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The same or similar components are designated in the different figures with the same reference numerals. 
     FIG. 1 shows a perspective view of a device  1  according to, and for implementing a method according to the present invention. 
     Device  1  comprises a frame  7  which is not shown in detail and has thereon a clamp  2 , a perforator  3 , a peeling unit  4  and a pusher cylinder  6 . Peeling unit  4  is driven by motor  5 . 
     Perforator  3  is shown in more detail in FIG. 2, which shows that perforator  3  comprises a head  8  with teeth  9  thereon. Head  8  is linear in the direction of arrow A and rotatably displaceable in the direction of arrow B. 
     By extending and rotating head  8  in the direction of respectively arrow A and arrow B a paper sleeve  11  of a package  10  having therein for instance a stack of covers for cans, such as drinks cans, can be perforated on a longitudinal end of package  10 . With angular displacement in the direction of arrow B over a greater radial distance than that between teeth  9  the relevant longitudinal end of package  10  is completely cut open; an alternative will be discussed hereinbelow. 
     In the embodiment shown in FIGS. 2 and 1 the head  8  of perforator  3  is suspended from a frame part  12  which is reciprocally displaceable along frame  7  in the direction of arrow C in FIG. 1. A drive cylinder  13  is provided for this purpose. Further shown in FIG. 1 is a rotation-driving cylinder  14  which is coupled eccentrically to head  8 . By pulling on the head  8  in the direction of arrow D it is possible with rotation-driving cylinder  14  to bring about rotation of head  8  in the direction of arrow B. If head  8  is connected to frame part  12  with a screw connection, extension of the head  8  can be brought about by shortening the rotation-driving cylinder  14  in the direction of arrow D in FIG.  1 . It is noted that teeth  9  are arranged on an inner ring  15  which is per se displaceable in the direction of arrow A relative to outer ring  16  of head  8 . A safety function can hereby be realized, which will be further described hereinbelow, wherein outer ring  16  first comes to lie against package  10 , only after which the teeth  9  on inner ring  15  are extended in order to perforate or cut through the sleeve  11  of package  10 . 
     A cutter unit  17  is further arranged which can be driven with a cylinder  18  in a reciprocal movement as according to arrow E in FIG. 1 during driving by the cylinder  18 . 
     The operations on package  10  with sleeve  11  are performed on a platform  19  with a fold, recess or deepened portion  20 , in which the package  10  comes to lie for removal of sleeve  11 . 
     Peeling unit  4  comprises peeling wheels  21  which are driven directly by motor  5  with belts  22 . Peeling wheels  21  can be brought together in order to peel the sleeve  11  from package  10 . Bringing together of peeling wheels  21  is indicated schematically in FIG. 1 with arrow F and is driven by a cylinder  23 . For this purpose the arms  24  of peeling unit  4  are rotatable on drive shafts  25 , which are per se connected to motor  5  in order to drive belts  22 . The arrangement of belts  22  shown in FIG. 1 otherwise ensures downward discharge of peeled sleeves  11 , for which purpose a collecting container (not shown) can be arranged under the device  1  shown here. In such a situation, wherein sleeve  11  is peeled from a package  10 , the piston rod  32  of pusher cylinder  6  must of course be retracted. 
     The clamp  2  comprises a stop  26  which can be moved up and downward in the direction of arrow G through driving by cylinders  27 . The force of stop  26  exerted on package  10  by cylinder  27  is preferably limited such that the content of package  10  is displaceable to some extent in sleeve  11 , while the sleeve  11  itself is held fast by clamp  2 . For this purpose use can for instance be made of a rubber covering  28  on the side of stop  26  directed toward package  10 . As a result of the friction exerted by rubber covering  28  the sleeve remains stationary when the content of package  10  is displaced to the left or right. 
     The operation of the device shown in FIGS. 1 and 2 will be elucidated hereinbelow with a number of schematic views. 
     FIG. 3 shows a lift  29  with which one package  10  at a time can be carried up along wall  30 . Package  10  then rolls over slope  31  to a flap  45 , which is pulled out of the way at a suitable moment by cylinder  45  in order to cause package  10  to drop onto platform  19 . More particularly the package  10  comes to lie in the recess or fold  20  in platform  19 . 
     The actual unpacking of package  10 , and thus the removal of sleeve  11  therefrom, can then take place. 
     As shown in FIG. 4, a start is made herewith by extending the piston rod  32  of pusher cylinder  6  in the direction of arrow H. Prior hereto the stop  26  is lowered, wherein the rubber covering  28  on the side of stop  26  directed toward package  10  engages the sleeve  11  and holds it stationary. Cylinder  27  is lowered in the direction of arrow G for this purpose. 
     Because piston rod  32  pushes the contents of package  10  in sleeve  11  in the direction of arrow H up to the longitudinal end  33  of package  10  where perforator  3  is situated, sleeve  11  is pulled taut over the longitudinal end  33  due to the pushing up of contents  10 . The operation of perforator  3 , which follows and will be described below, is hereby improved. 
     As shown in FIG. 5 a , the design of outer ring  16 , and therefore also of inner ring  15 , is adapted to the specific embodiment of a package  10  having covers for drinks cans therein. A safety function is hereby realized. If the profile  34  of a can cover is facing in the correct direction, a groove  35 , which is annular, is remote from the teeth  9  on inner ring  15 . When head  8  is displaced forward in the direction of longitudinal end  33  of package  10  while sleeve  11  is stretched tautly thereover, this being described with reference to FIG. 4, the outer ring  16  fits partly into groove  35  with a shoulder  36 . Only when this position has been reached is movement of the inner ring  15  with teeth  9  thereon enabled. 
     On the other hand, as shown in FIG. 5 b , this movement is not enabled if the can covers lie in the opposite orientation in sleeve  11 , as is shown in FIG. 5 b . Outer ring  16  cannot penetrate into the annular grooves  35  of the profile  34  of the can covers, so that the movement of inner ring  15  with the teeth thereon does not come about either. An alarm function is preferably coupled hereto, so that an employee can intervene to remove the roll or makes use of an automated option to remove or reverse the package  10 . 
     In the embodiment shown here perforations are only arranged with the head in longitudinal end  33  of sleeve  11  of package  10 . As shown in FIG. 6, cylinders  27  of clamp  2  and pusher cylinder  6  are then released, i.e. deactivated, whereafter drive cylinder  13  is activated for movement of head  8  in the direction of arrow C so as to displace head  8  to the left in FIG.  6 . Because cylinders  27  and pusher cylinder  6  have been deactivated, they do not form an obstruction. Head  8  thus carries package  10  along in its movement to the left in FIG.  6 . Only a minimal stroke is hereby required for good operation of pusher cylinder  6 , which enhances simplicity. 
     As shown in FIG. 7, drive cylinder  13  for the head  8  of perforator  3  is then deactivated, and cylinder  27  of clamp  2  is activated, only after which the pusher cylinder  6  is also activated again. This is indicated schematically in FIG. 7 with arrows C, G, H in alphabetical order. The contents of package  10  are pressed out of sleeve  11  at the longitudinal end  33  thereof by holding the sleeve  11  fixedly with stop  26  and pushing up the piston rod  32  of pusher cylinder  6  in the direction of arrow H. In the case of a stack of can covers in sleeve  11  the head  8  moves only very slowly sideward to the right in FIG. 7 in order to prevent the possibility of the covers at the longitudinal end  33  of the stack being pushed out of sleeve  11  falling over. At the end of sleeve  11  situated opposite longitudinal end  33  there is hereby simultaneously created a free part of sleeve  11  without the content of the package  10  herein for the purpose of engagement by peeling wheels  21 . 
     Peeling wheels  21  have a form as shown in FIG. 7 a . These peeling wheels  21  comprise a radial recess  36  whereby peeling wheels  21  can engage onto sleeve  11  round the piston rod  32  of pusher cylinder  6 , whereafter the piston rod  32  of pusher cylinder  6 , as shown in FIG. 8, can be retracted in the direction of arrow H from the engagement between wheels  21 . 
     Peeling wheels  21  can subsequently be driven by setting motor  5  into operation and the sleeve  11  can be peeled away after cylinders  27  of clamp  2  have been deactivated in the direction of arrow G. Perforator  3  is herein also placed at a distance, as also shown in FIG.  8 . The platform  19  is preferably placed at an angle, wherein the end at the side of perforator  3  is higher than on the side of peeling unit  4 . This prevents the products in the package falling over during peeling of sleeve  11 , which would be particularly-undesirable in the case of drinks can covers. Additionally or alternatively the perforator  3 , and in particular the head  8  thereof, can be held in the vicinity of the longitudinal end of package  10  to prevent tipping over of for instance drinks can covers. 
     The peeling of sleeve  11  is shown schematically in FIG.  9 . Peeling wheels  21  are driven as long as a sleeve  11  is still present round package  10 . A schematically shown photo-detector  37  detects the presence of sleeve  11  and generates a signal indicating that the driving of peeling wheels  21  can be ended when the sleeve has been completely peeled. 
     During the removal of sleeve  11 , and therefore during driving of peeling wheels  21 , the peeling wheels, and more particularly arms  24 , are moved intermittently away from and toward each other. This effectively prevents sleeve  11  crumpling during peeling thereof with peeling wheels  21 . This would result in the sleeve  11  of package  10  being able to twist out of the recess  20  in platform  19 . This would be particularly adverse for the discharge of the contents of package  10 , such as the drinks can covers, but is efficiently prevented by intermittently opening and closing the space between peeling wheels  21 . 
     FIG. 10 shows the manner in which the cutter unit  17  descends in front of the contents of the removed sleeve  11  of package  10 . It is noted that sleeve  11  is discharged downward between the belts  22  in FIG. 1 to a waste container, which is not further shown. Cutter unit  17  descends in front of the contents of package  10  when peeling wheels  21  move apart in order to thus hold together the contents of package  10 . As described with reference to FIG. 9, wheels  21  move apart only when photo-detector  37  has detected that the whole sleeve  11  of package  10  has been peeled away. As also described above, the head  8  of perforator  3  can fit more closely onto the contents of package  10  than is shown in FIG. 10 in order to hold these contents together between this head  8  and cutter  17 . This is particularly advantageous in the case of a content consisting of a plurality of items, such as drinks can covers. The unpacked content of package  10  can then be transferred in the manner shown in FIG. 11 to a discharge conveyor  40  using a slide  39 , which is driven by a cylinder  38  in the direction of arrow I. 
     The operation of cylinder  38  is only enabled once a detector  41  has detected that a previously unpacked content of a package has shifted up sufficiently through processing thereof to allow space to the just unpacked content of a package  10 . Further processing of the content of the packages then continues in the direction of arrow J, wherein the process of unpacking other packages  10  restarts to remove sleeves  11  therefrom. 
     It is noted that discharge conveyor  40  is positioned at the front of device  1  in the view of FIG.  1 . As shown in FIG. 3, the packages  10  to be unpacked are supplied from the rear in the view of FIG. 1 for removal of sleeve  11  thereof. 
     It is noted that many additional and alternative embodiments will occur to the skilled person after perusal of the foregoing relating to the present invention. The sequence of FIGS. 6 and 7 can thus be omitted if a choice is made for a pusher cylinder  6  with a sufficiently long stroke. This is per se less advantageous however in respect of the space required for device  1  and the complexity of the components, particularly pusher cylinder  6 , which must be able to make a longer stroke. Such an option nevertheless lies within the scope of the present invention. The peeling progression during removal of sleeve  11  of package  10  can also take place in a random other embodiment. After the removal of the longitudinal end of sleeve  11 , the released edges of sleeve  11  can thus be engaged and the sleeve pulled back over itself for peeling thereof. The sleeve does not herein have to be cut or severed in longitudinal direction of package  10 , and those risks involving damage to the content of package  10  are avoided.