Abstract:
An apparatus for transferring and erecting folded boxes between a dispensing station and a receiving station of a cardboard box making machine. The apparatus includes a plurality of suction systems with suction heads. The suction heads, which each rotate about a common pivot axis, are each coupled to a separate drive mechanism. The device mechanism varies an angular speed of rotation of the respective suction head on a revolution about the pivot axis, so as to adapt this speed to a particular function required at that time. The apparatus has a high output and makes easy adaptation to various folded boxes possible while simultaneously achieving high functional safety and reliability.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an apparatus for transferring objects lying flat, especially folded boxes of the kind known from European Patent Disclosure EP 0 434 961 A1. The known apparatus has a star-shaped, continuously driven rotor with a plurality of suction heads disposed in staggered fashion on the rotor. When a folded box is transferred from a folded box magazine to between the drivers of a continuously driven conveyor chain, the suction head that holds the folded box follows an intrinsically closed cycloidal path, and the folded box, lying flat, is erected between a folded box magazine and the conveyor chain. 
     A disadvantage of this known apparatus is that because of the cycloidal path, the suction cup on pulling a folded box from the folded box magazine does not execute a solely vertical motion, and on transferring the folded box to between the drivers of the conveyor chain, the box does not execute a forward or horizontal motion that is adapted to the speed of the conveyor chain. As a result of both these factors, the disposition and adaptation of the rotor, folded box magazine and conveyor chain requires relatively major effort, especially for folded boxes whose format and quality of material are critical, if uninterrupted operation of the apparatus is to be possible. 
     If one seeks to increase the output of the known apparatus, this can be done by increasing the number of suction heads disposed on the rotor, or by increasing the rotary speed (rpm) of the rotor. Increasing the number of suction heads on the rotor entails increased engineering effort and expense, on the one hand, and on the other, is subject to space limitations because of the disposition between the folded box magazine and the conveyor chain. Increasing the rotor rpm is problematic, too, because the load and the forces on the folded box in the erection process can then become excessive. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The apparatus according to the invention for transferring objects lying flat, especially folded boxes, as defined herein has the advantage over the prior art that the course of motion of the suction head can be adapted optimally to the particular function required. This means that a folded box blank is being pulled out of the folded box magazine, lateral motion of the suction head relative to the folded box magazine is absent, or virtually absent, as long as the folded box blank is located in the region of the folded box magazine. Furthermore, the transfer of the erected boxes to between the drivers of the conveyor chain is done at a horizontal speed that is adapted to the conveyor chain. 
     In addition, with the apparatus of the invention, an especially high output can be attained. This is because along the first segment, in which the first folded box lying flat is erected, the folding box blank is conveyed at a speed it can tolerate, and thus the forces acting on the box in the erection process are limited. By comparison, in the second segment, in which the suction head moves from the conveyor chain toward the folded box magazine in order to take up the next folded box blank, the speed of the suction head can be increased. The overall result, compared with known apparatuses, is a higher, variously variable rotary speed of the suction head. 
     The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a front view of an apparatus according to the invention, partly in simplified form; and 
     FIG. 2, partly in section, shows a side view of the apparatus of FIG. 1, again partly in simplified form. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The apparatus  10  shown in the drawings is used to take folded boxes  1 , lying flat, from a folded box magazine  11  in a dispensing station A and transfer the folded boxes  1 , while simultaneously erecting them, to a receiving station B; in the exemplary embodiment they are transferred to between pairs of parallel drivers  12 ,  13  of a continuously driven conveyor chain  5  of a cardboard box making machine, the drivers  12 ,  13  being disposed on both sides of a stationary bottom rail  14 . To that end, the apparatus  10  disposed between the folded box magazine  11  and a deflection region  16  of the conveyor chain  15  has three suction systems  17 ,  18 ,  19 , which revolve around a common pivot axis  21 . 
     The first suction system  17  has a shaft  25 , guided in two bearings  23 ,  24 , each on one end of the shaft. Near the first bearing  23 , a first pulley  26  is connected to the shaft in a manner fixed against relative rotation, and the shaft is connected via a first toothed belt  27  to a first drive mechanism, preferably a servo motor  30 . Approximately in the middle of the shaft  25 , two delivery devices  28 ,  29  aligned with one another and spaced apart from one another are likewise connected to the shaft  25  in a manner fixed against relative rotation. 
     A guide  33  is embodied in each of the end faces, facing toward one another, of the radially protruding arms  31 ,  32  of the delivery devices  28 ,  29 , and one suction head  35  is disposed radially movably in each guide  33 . The suction head  35  has a guide  36  which is displaceable in the guides  33 , and a bar-like first suction plate  37  is secured on the side of the guides that faces away from the arms  31 ,  32 . Two rows, in the exemplary embodiment, each with four suction cups  38 , are disposed on the side of a first suction plate  37  facing away from the guide  36 . A first connection  39  is located on the first suction plate  37  and communicates, via a flexible hose, not shown, with a second connection  41  disposed in the first delivery device  28 . Via a conduit  42  formed in the shaft  25 , the second connection  41  leads to a first control ring  43  disposed on the shaft  25  in a manner fixed against relative rotation. A suction groove  44  is embodied in the control ring  43 , in its face end remote from the first pulley  26 , in the angular region between the folded box magazine  11  and the conveyor chain  15 . The suction groove  44  is operatively connected to a first, stationary negative pressure ring  45  that rests on the control ring  43 . A negative pressure conduit  46  which communicates with a negative pressure source  47  discharges in the negative pressure ring  45 , on the side toward the suction groove  44 , so that the suction cups are subjected to negative pressure when the negative pressure conduit  46  and the suction groove  44  coincide. 
     In order to generate the aforementioned radial motion of the suction head  35 , one guide roller  48  is disposed on each of the two lateral end faces of the first suction plate  37 . The guide rollers  48  roll along guide paths  49  of two stationary guide plates  50 , which are disposed on both sides of the delivery devices  28 ,  29 . 
     For erecting a folded box  1  along the transfer route from the folded box magazine  11  to the conveyor chain  15 , a cardboard box bracing means  52  and erection prongs  53 , which are disposed on the broad sides of the first suction plate  37 , are associated with the suction head  35 . The erection prongs  53  are secured in stationary fashion to one of the two arms  31 ,  32  of the delivery devices  28 ,  29  and each has one roller  54  on one of its ends. By comparison, the cardboard box bracing means  52  is disposed pivotably, via a lever mechanism, not shown, on an extension  55  secured to the guide  36  and penetrates the folded box magazine  11 , inside a suitably embodied recess. 
     The second and third suction systems  18  and  19  are constructed similarly to the first suction system  17 . In particular, they too have radially movable suction heads  35  with suction cups  38 , which are guided by guide rollers  48  in the guide paths  49  of the guide plates  50 . 
     The drive of the second suction system  18  is effected by means of a first, split hollow shaft  57  that has two portions  58 ,  59 ; a second pulley  61  parallel to the first pulley  26  is disposed on the first portion  58  in a manner fixed against relative rotation. The second pulley  61  is in turn coupled via a second toothed belt  62  to a separate drive mechanism, preferably a servo motor  30   b.    
     The two portions  58 ,  59  of the first hollow shaft  47  each extend to the two respective delivery devices  28 ,  29  secured to the shaft  25 , where the two delivery devices  63 ,  64  for the suction head  35  of the second suction system  18  are disposed in a manner fixed against relative rotation on the portions  58 ,  59 . The guide  66  together with the second suction plate  67  is guided radially movably in the two delivery devices  63 ,  64 . A second control ring  68  is secured to the portion  59  on the side opposite the first delivery device  63 . The second control ring  68  cooperates with a second negative pressure ring  69 , which is slipped onto the shaft  25  and is disposed between the two control rings  43 ,  68 . 
     A connection  71  that connects the negative pressure source  47  with the suction cups  38  of the second suction system  18  and subjects them to negative pressure in accordance with the angular position of the suction head  35  is embodied in the delivery device  63 , the portion  59  of the hollow shaft  57 , the control ring  68  and the negative pressure ring  69 . 
     The delivery devices  72 ,  72  of the third suction system  19  that embrace the delivery devices  63 ,  64  of the second suction system  18  are secured in a manner fixed against relative rotation to portions  74 ,  75  of a second hollow shaft  77 , which in turn surrounds part of the first hollow shaft  57 . A third pulley  78  is secured to the portion  74  and is driven via a third toothed belt  79  by a third separate drive mechanism, again preferably a servo motor  30   b.  On the end of the portion  75  opposite the delivery device  72 , there is a third control ring  81 , which cooperates with a third negative pressure ring  82  disposed between the second control ring  68  and the end of the portion  75 . A connection  83  that communicates with the negative pressure source  47  is embodied in the negative pressure ring  82 , control ring  81 , portion  75 , and delivery device  72 . Because of the angular position of the suction head  35  of the third suction system  19 , however, only the portion of the connection  83  that is formed in the third negative pressure ring  82  is visible in the drawing. From the delivery device  72 , the connection  83  leads by means of an elastic hose  84  to the third suction plate  87  communicating with the guide  86 . 
     To prevent or reduce air leakage losses between the control rings  43 ,  68 ,  81  and negative pressure rings  45 ,  69 ,  82  abutting one another, the control rings  43 ,  68 ,  81  and the negative pressure rings  45 ,  69 ,  82  are disposed between two spacer rings  89 ,  90 , between which there is also a compression spring  91 , which presses the control rings  43 ,  68 ,  81  and the negative pressure rings  45 ,  69 ,  82  against one another. 
     As mentioned, the radial displaceability of the suction systems  17 - 19 , or of their suction heads  35 , is effected by the guide plates  50  with the guide paths  49  formed in them and the guide rollers  48  rolling in these paths. For pulling one folded box  1 , lying flat, from the folded box magazine  11 , the suction cup  38  of the applicable suction system  17 - 19  must dip briefly into the lower opening cross section of the folded box magazine  11 , which is open except for the retaining lugs  92  for the folded boxes  1 . This relative motion between the suction cup  38  and the folded box magazine would, if a horizontal motion between the folded box magazine  11  and the applicable folded box  1  as it is being taken out is to be largely avoided, make the guide paths  49  of the guide plates  50  quite steep and hence would put a major load on the drive mechanism in question. For this reason, and because a horizontal motion between the particular folded box  1  and the folded box magazine  11  as the box is being taken but can be averted entirely, it is preferably provided that the folded box magazine  11  also be movable. This is accomplished by means of two lifting cylinders  93 , secured to the housing of the folded box magazine  11 . For taking a folded box  1  out while it lies flat, the lifting cylinders  93  move the folded box magazine  11  first in the direction of the suction cups  38 , putting the suction cup into contact with one side of the folded box  1 , and then in the opposite direction, so that the folded box  1  overcomes the retaining lugs  92 . It is understood that instead of lifting cylinders  93 , other means capable of effecting a relative motion of the folded box magazine  11  to the suction cups  38  are also conceivable. 
     The apparatus  10  described above functions as follows: 
     The three suction systems  17 - 19  are each rotated counterclockwise by their own drive mechanism via the toothed belts  27 ,  62  and  79 . It is understood that an angular spacing between the suction systems  17 - 19  such that they do not touch one another is provided. For pulling a folded box  1 , lying flat, out of the folded box magazine  11 , the applicable suction system  17 - 19  is stopped underneath the folded box magazine  11 . In this position, the suction cups  38  are radially spaced apart from the pivot axis  21  far enough that the roller  54  of the erection prong  53 , the prong being stationary relative to the pivot axis  21 , is located below the level of the suction cups  38 . 
     The folded box magazine  11  is now lowered far enough by the lifting cylinders  93  that the suction cups  38  subjected to negative pressure come into contact with one side of the folded box  1 . Once the folded box magazine  11  has been lifted again by the lifting cylinders  93 , the folded box  1  is free. After that the applicable suction system  17 - 10  is rotated in the direction of the drivers  12 ,  13  of the conveyor chain  15  along a first path segment  94 , which covers 180°. Along this path segment  94 , the spacing of the suction cups  38  from the pivot axis  21  initially decreases because of the correspondingly embodied guide paths  49 , so that once the cardboard box bracing means  52  has been pivoted into contact with the folded box  1 , the folded box  1  can be erected by the erection prongs  53 , whose roller  54  presses against one side wall of the folded box  1  (FIG. 1, suction system  18 ). After that, the spacing of the suction cups  38  from the pivot axis  21  increases again, in order not to come into contact with the drivers  12 ,  13  of the conveyor chain  15  when the erected folded box  1  is introduced between the drivers  12 ,  13 . The angular speed of the suction system  17 - 19  along the first path segment  94  depends on the format and the quality of material of the folded box  1  and should be selected to be high enough, for the sake of high output of the apparatus  10 , that the folded box  1  can still be reliably opened and erected without experiencing an excessive load on its side walls. 
     For introducing the folded box  1  into the conveyor chain  15 , it is essential that the applicable suction system  17 - 19  be adapted in its angular speed by its associated drive mechanism in such a way that the transfer of the folded box  1  occurs at a horizontal speed that is at least nearly the same as the conveying speed of the continuously driven conveyor chain  15 . Additionally, because the folded box  1  is introduced in the deflection region  16  of the conveyor chain  15 , the trailing driver  13  of a pair of drivers associated with a folded box  1  is also positioned obliquely, which makes the introduction possible. 
     From the moment when the folded box  1  is placed between the drivers  12 ,  14  of the conveyor chain  15 , the suction cups  38  are no longer subjected to negative pressure, and thus the folded box  1  is now fed onward along the bottom rail  14  solely by the conveyor chain  15 . After that the suction cups  38  are returned to where they were, and the cardboard box bracing means  52  is pivoted out of the way via the lever mechanism. 
     For the sake of achieving high output of the apparatus  10 , the applicable suction system  17 - 19  is now rotated onward counterclockwise in the shortest possible time, that is, at the highest possible angular speed, over its second path segment  95 , again covering 180°, so that the next folded box  1  can be taken out of the folded box magazine  11 . The angular speed of the suction system  17 - 19  along the second path segment  96  is limited then only by the mechanical load-bearing capacity of the apparatus  10  and in particular of its drive components, but not by the properties of the folded box  1 . 
     To supplement the above-described exemplary embodiment, it is naturally also conceivable for the conveyor chain  15  to be driven intermittently, instead of continuously. In that case, the applicable suction system  17 - 19  stops, in the stopped phase of the conveyor chain  15 , to transfer a folded box  1  to between the drivers  12 ,  13 . 
     In addition, the output of the apparatus  10  can also be adapted to a given intended use by varying the number of suction systems  17 - 19 . The number of suction systems  17 - 19  is then limited only by the complication and hence cost of the apparatus, and by the space needed for the suction systems  17 - 19 , but if only a low output is needed it can even be reduced to a single suction head  35  or a single suction system. 
     The foregoing relates to a preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.