Abstract:
A device for packing flat articles in transport containers includes a feeder for feeding the flat articles in imbricated form. A conveyor disposed downstream of the feeder, in transport direction of the articles, has an at least approximately vertically extending end for discharging the articles into the transport containers at a filling location. Electrically operated controllable servomotors serve as drives for the conveyor. Equipment is provided for further conveying the transport containers at the filling location.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a device for packing flat articles in transport containers, in particular folded-flat folding boxes in casing cartons, having a feeder for feeding the flat articles in imbricated form. A conveyor disposed downstream of the feeder, as viewed in a travel direction of the flat articles, has an at least approximately vertically extending end for discharging the articles into the transport containers at the filling location. Equipment is provided for further conveying the transport containers at the filling location. 
   German Published, Non-Prosecuted Patent Application 28 25 647, corresponding to UK Patent Application GB 2 022 558, discloses a device of the general type described in the introduction hereto, namely for packing folded-flat folding boxes in casing cartons, wherein a conveyor has a lowering rail and a pivoting rail, each with a revolving belt. The folding boxes, which are fed in imbricated form, are conveyed between the belts into casing cartons as transporting containers. The lowering rail therein serves as an abutment, which interacts with the pivoting rail at the discharge location in order for the folding boxes to be guided as far as possible into the definitive position thereof in the transport container. In order to allow precise positioning of the lowering and pivoting rails in the transport container, the at least approximately vertically moveable lowering rail has a longitudinally displaceable switching rail fastened thereon. The switching rail projects beyond the lowering rail in the downward direction and actuates a switch as soon as it is positioned on the base of the transport container. As a result, the operation of lowering the lowering and pivoting rails by a hydraulic drive is stopped at a defined distance from the base of the transport container. Adjustment of the distance, for example for adaptation to different folding-box formats, is only possible by a mechanical intervention in the construction of the conveyor. 
   German Published, Non-Prosecuted Patent Application 28 25 648, corresponding to UK Patent Application GB 2 030 952, likewise describes a device for introducing folding-box blanks into transport containers, wherein the blanks are guided between a top belt and a bottom belt of the conveyor. The bottom and top belts of the conveyor therein are driven by independent drives which are not specifically described. A further packing device of that type is described in German Published, Non-Prosecuted Patent Application 2 261 416. The bottom belt of the conveying configuration wraps around a drive roller and deflecting rollers, which define a curved conveying path. Specific details regarding the construction of the drives are also not disclosed therein. 
   SUMMARY OF THE INVENTION 
   It is accordingly an object of the invention to provide a device for packing flat articles in transport containers, in particular folded-flat folding boxes in casing cartons, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which reliably conveys and discharges flat articles at high speeds, for quick adjustment to different formats of the articles and/or transport containers and which allows for wide-ranging automation and space-saving construction. 
   With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for packing flat articles in transport containers, comprising a feeder for feeding the flat articles in imbricated form. A conveyor disposed downstream of the feeder, in transport direction of the articles, has an at least approximately vertically extending end for discharging the articles into the transport containers at a filling location. Electrically operated, controllable servomotors serve as drives for the conveyor. Equipment is provided for further conveying the transport containers at the filling location. 
   In accordance with another feature of the invention, the conveyor has, at an end thereof, a lowerable pivoting rail and an at least approximately vertically lowerable rail, and conveying belts each mounted on a respective one of the rails. 
   In accordance with a further feature of the invention, the conveyor has a conveying section subdivided into at least two independently drivable sub-sections disposed behind one another and each having upper and lower belts. 
   In accordance with an added feature of the invention, there is provided a sensor disposed in an end region of the conveyor. The sensor is operable in a contactless manner for determining a distance between the discharge end of the conveyor and the base of a respective transport container. 
   In accordance with an additional feature of the invention, the sensor is an ultrasonic sensor. 
   In accordance with a concomitant feature of the invention, the flat articles are folded-flat folding boxes, and the transport containers are casing cartons. 
   Thus, the object of the invention is achieved by providing a conveyor having electrically operated, controllable servomotors as drives therefor. It is preferable in this case for the conveyor to have a conveying section subdivided into two independently drivable sub-sections. This offers the advantage that, once one layer or row has been introduced into the transporting container, it is possible to interrupt the continuous supply of the articles within the conveying section in order to move a vertically lowering and pivoting rail and/or the transport container into the position which is necessary for introducing the next layer. The first sub-region of the conveying section in this case serves as a space for accumulating the articles of the next layer. 
   A further advantage is achieved if the motors of the upper and lower belts can be operated at different speeds. This makes it possible to correct the degree of imbrication, i.e., the extent of overlap, of the articles, during the conveying operation. 
   A sensor which is preferably fastened on a stationary part in an end region of the conveyor operates in a contactless manner and senses the perpendicular distance to the base of the transport container or to a layer of articles. This makes it possible for the distance between the discharge end of the conveyor and the base of the transport container or a layer of articles to be controlled in a stepless or continuous manner. In addition, there is no need for any manual intervention in the packing device for the purpose of adjusting or adapting the distance to the dimensions of the transport container or of the articles which are to be packed. Integrating the sensor into the circuit of a control system permits the distance that is to be maintained to be automatically predetermined and readjusted during operation. It is possible to fasten to the lowering rail basically any sensor which operates in a contactless or non-contact manner and is suitable for distance-determining purposes, for example a laser sensor or an inductive sensor. An ultrasonic sensor is preferred. 
   Other features which are considered as characteristic for the invention are set forth in the appended claims. 
   Although the invention is illustrated and described herein as embodied in a device for packing flat articles in transport containers, in particular folded-flat folding boxes in casing cartons, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
   The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic, side-elevational view of a packing device according to the invention; 
       FIG. 2  is a plan view of the packing device wherein individual constituent parts are illustrated diagrammatically; 
       FIG. 3  is a side-elevational view of a feeder for feeding casing cartons to a filling device; 
       FIG. 4  is a front-elevational view of  FIG. 3 ; 
       FIG. 5  is a front, side and top perspective view of  FIG. 3 ; 
       FIG. 6  is an enlarged, fragmentary view of  FIG. 1 , showing the conveyor thereof; 
       FIG. 7  is an enlarged, fragmentary view of  FIG. 6 , for clarifying the filling operation; 
       FIG. 8  is a front, side and top perspective view of the beginning of the conveyor; 
       FIG. 9  is a front, side and top perspective view of the folding-box feeder disposed upstream of the conveyor and showing the detailed construction thereof; 
       FIG. 10  is an enlarged, fragmentary, cross-sectional view of the conveyor of the folding-box feeder; and 
       FIG. 11  is a top, side and front perspective view of the belt conveyors at the filling location. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now in detail to the figures of the drawings and first, particularly, to  FIG. 1  thereof, there is seen an exemplary embodiment of a packing device serving for packing folded-flat folding boxes  1  in casing cartons  2 . The packing device is disposed downstream of a folding-box adhesive-bonding machine, wherein folding boxes are produced from blanks. 
   The packing device starts with a folding-box feeder  3 , to which the folded-flat folding boxes  1  are fed in imbricated form from the folding-box adhesive-bonding machine. The feeder  3  has, as conveyors, two belts  4 , whereon the folding boxes  1  are conveyed in a horizontally disposed condition. The feeder  3  illustrated in  FIGS. 1 ,  2  and  9  is preferably constructed in such a way that the folding boxes  1  are conveyed further either in a rectilinear condition, without being rotated, or in a condition wherein they have been rotated through 90° to the lefthand or righthand sides of the respective figures. This makes it possible for the folding boxes  1  to be packed in the casing cartons  2  in an upright condition either with the leading edge or one of the side edges thereof at the bottom of the respective figure. If the blanks  1  are to be rotated through 90°, they are supplied to the belts  4  via a lateral roller conveyor  5  with a conveying section curved through 90° and, during transfer, they are aligned on a stop  6  which is parallel to the belts  4  and can be adjusted transversely to different box formats. If the folding boxes  1  are to be conveyed further by the folding-box adhesive-bonding machine in a rectilinear state, without being rotated, they are fed centrally in the direction of an arrow  7 . In order for the respectively desired supply inlet  5  or  7  to be adjustable or settable, the feeder  3  and the rest of the packing device are mounted in such a way that they can be adjusted transversely on rollers  8 , as illustrated in  FIG. 1 . 
   The feeder  3  illustrated in  FIG. 2  allows folding boxes  1  to be conveyed further only in a rectilinear condition or in a condition wherein they have been rotated through 90° to the righthand side of  FIG. 2 . If rotation through 90° to the lefthand side is also to be permitted, the feeder  3  has, on the second longitudinal side, i.e., at the top in  FIG. 2 , a further roller conveyor, of which the conveying section runs rotatively through 90° to the lefthand side of the figure. 
   The folding boxes are transferred from the feeder to a conveyor  9  which includes, as conveying elements, at least one pair of belts with a top belt  27 ,  28  and a bottom belt  29 ,  30 , between which the folding boxes  1  are retained and conveyed. The conveying section of the conveyor  9  initially curves upwardly and then downwardly, and terminates with an approximately vertical profile at the filling location, at which the folding boxes  1  are packed in an upright condition in the casing cartons  2 . 
     FIG. 2  is a plan view of the configuration of the various conveyors by which empty casing cartons  2  are fed to the filling location at the end of the conveyor  9 , and cartons  2  filled with folding boxes are transported away. 
   It is an important feature for the invention that the empty casing cartons  2 , which are to be filled, be fed to the filling location in a rectilinear condition counter to the transporting direction of the folding boxes  1 . The feeding direction is represented by an arrow  12  in  FIG. 2 . For this purpose, the packing device has, downstream of the filling location, as viewed in the conveying direction of the boxes  1 , a belt conveyor  14  which conveys in the direction of the arrow  12 , and whereon the empty casing cartons  2  are positioned from behind by an operator represented at reference numeral  15 . The belt conveyor  14 , which is provided with a belt drive, transfers the empty casing cartons  2  to two lateral belt conveyors  16  and  17 , which extend through the filling region by way of vertically running belts. The two belt conveyors  16  and  17 , which are respectively movable transversely by a drive, act upon the sides of the casing carton  2  at the respective bottom and firmly clamp the carton therebetween. For filling purposes, the end of the conveyor  9  is moved into the casing carton  2 . During the filling operation, the two belt conveyors  16  and  17  move the casing carton  2  farther at the required speed, in order for the boxes to be disposed in the casing carton  2  in a condition wherein they stand in a row directly adjacent to one another. In order to ensure that the casing carton  2  be moved forward exclusively via the belt conveyors  16  and  17  during the filling operation, freely rotatable rollers  18  are disposed as a supporting surface in the filling region, so that the casing cartons  2  stand on the rollers  18 . The belt conveyors  16  and  17  are followed, as viewed in the transporting direction of the casing carton  2 , by a roller conveyor  19  which has driven rollers, and further transports the filled cartons  2 . 
   Hold-down bars  10  and  11  are preferably disposed along the conveying path of the casing cartons  2  to as far as the filling location. The hold-down bars force the cover flaps of the casing cartons  2  outwardly and thus keeping the cartons  2  in an open position. 
   The two lateral belt conveyors  16  and  17  are illustrated in greater detail in  FIG. 11 , and move the casing cartons  2  forward during the filling operation. The two belt conveyors  16  and  17  are preferably constructed in a mirror-inverted manner relative to one another and are, respectively, individually mounted so as to be adjustable transversely to the transporting direction thereof, by a non-illustrated linear drive. Each belt conveyor  16 ,  17  preferably has two conveying belts  80  and  81 , which are driven independently of one another and of which the conveying strands run vertically, respectively, and are disposed in alignment behind one another. Each of the revolving conveying belts  80 ,  81  is deflected by deflecting rollers  82 ,  83  which are fastened, by way of vertical spindles, on a common longitudinal carrier  84  so that the conveying strand, respectively, on the inside, runs outside the region of the longitudinal carrier  84 . Each conveying strand is supported on the rear side thereof by resilient elements  86 . Each longitudinal carrier  84  is adjustable transversely by a linear drive, with the result that the two belt conveyors  16 ,  17  can be moved towards one another and away from one another in order to retain a casing carton  2  in a clamped condition. Each conveying belt  80 ,  81  of a belt conveyor  16 ,  17  is connected to a rotary drive  85 , which drives one of the deflecting rollers  83  via a mitre gear. The two-part form of each belt conveyor  16 ,  17  offers the advantage that two independent conveyors are provided behind one another. This makes it possible for empty casing cartons to be fed by the two first conveying belts  80 , while filled casing cartons  2  are transported away by the second conveying belts  81 . The drives  85  used for the conveying belts  80 ,  81  are preferably electric servomotors which allow precise control of the advancement of a casing carton  2  during the filling operation. 
   The construction of the conveyor  9  is illustrated in greater detail in  FIG. 6 . It has, at the end thereof, a lowerable pivoting rail  32  and a lowerable rail  22  that is lowerable in an at least approximately vertical movement to as far as the base  23  of a casing carton  2 .  FIG. 6  illustrates the phase position wherein the rail has been moved into the carton  2 . Fastened to the stationary mounting of the vertically lowerable rail  22  is a sensor  24  which, in a contactless manner, determines the distance between the vertically bottom end of the vertically lowerable rail  22  and the base  23  of the casing carton  2 . The sensor  24  that is preferably used is an ultrasonic sensor which is fastened to the load-bearing structure of the conveyor  9  via an angle plate  26 . The sensor  24  permits the distance between the end of the vertically lowerable rail  22  and the base  23  of the casing carton  2 , or a layer of boxes  1  which is already located in the casing carton, to be adjusted automatically. 
   The conveyor  9  has at least one driven pair of belts including a top or upper belt  27 ,  28  and a bottom or lower belt  29 ,  30 . The boxes  1  are conveyed in a condition wherein they lie horizontally between the respective belts  27 ,  29  and  28 ,  30  and are retained thereby. It is preferable for two driven pairs of belts to be disposed behind one another along the conveying section, it being possible for the top belts  27 ,  28  and the bottom belts  29 ,  30 , respectively, thereof to be driven independently of one another. In the preferred embodiment illustrated in the figures, the conveyor  9  has two conveying sections with, respectively, two separate belts  27 ,  29  and  28 ,  30 , each belt  27 ,  28 ,  29 ,  30  having a dedicated independent drive  31 . The drives  31  which are used are electrically operated, controllable servomotors which allow precise control of the respective belt speed. The top belt  28  of the second conveying section is mounted on the vertically lowerable rail  22 , and the associated bottom belt  30  is mounted on the pivoting rail  32 . 
   Dividing the conveying section of the conveyor  9  into two sub-sections offers the advantage that, respectively, the predetermined number of boxes  1  of one layer can be deposited in casing cartons  2  by the second pair of conveying belts  28 ,  30 , while the boxes  1  for the next layer are accumulated and held back in the first pair of conveying belts  27 ,  29 . The supplying of the boxes  1  into the casing cartons  2  can be interrupted in order to move the vertically lowerable and pivotable rails  22  and  32 , respectively, into the position which is necessary for depositing the next layer or in order to convey up a new empty casing carton. 
   In order that the vertically lowerable rail  22  and the pivotable rail  37  may be lowered into a casing carton  2 , they are each provided with a separate lifting drive  36 ,  38 . It is also preferable for the drives  36 ,  38  to be electrically operated, controllable servomotors which allow precise control of the lowering movement.  FIG. 7  illustrates the vertically lowerable rail  22  and the pivotable rail  32  in the operating position thereof. 
   The region of the belt conveyor  14  which conveys the casing cartons  2  to the filling location is illustrated in greater detail in  FIGS. 3 to 5 . The belt conveyor  14  has a conveying belt  40  which corresponds, in terms of width, at least to the width of a casing carton  2 . The belt drive that is used is a servomotor, which drives the outlet-side deflecting roller  42  of the belt  40 . On the inlet side, the conveying section is bounded by the deflecting roller  41  of the belt  40 . 
   Disposed at a slight distance above the conveying plane of the belt  40  are two longitudinal carriers or support beams  44  whereon, respectively, a row of guide rollers  43  are mounted so as to be freely rotatable at a distance apart from one another. The spindle of each roller  43  is inclined in the conveying direction at an acute angle to the vertical. The longitudinal carriers  44  with the rollers  43  fastened thereon are adjustable transversely so that the rollers, respectively, guide a casing carton  2  in the bottom region of the side walls. The inclination of the rollers  43  causes the casing carton  2 , which is conveyed by the belt  40 , to be forced onto the belt  40 . The increased contact pressure improves the conveying and, at the same time, prevents the base flaps of the casing carton  2  from opening and forcing the latter upwardly. Because the base flaps of the casing carton  2  are pressed flatly onto the belt  40 , the planar base of the casing carton  2  is made available to the distance or spacing sensor  24  as a defined reference surface for distance-determining purposes. 
   At least one of the longitudinal carriers or support beams  44  is mounted so as to be adjustable transversely, with the result that the distance between the two longitudinal carriers or support beams  44  can be set to different casing-carton widths. 
   In the simplest form, the packing device includes only the aforedescribed parts with the conveying sections  14 ,  18  and  19 . If the cartons  2  are to be filled with a number of layers of boxes  1  above one another and/or with several rows of boxes beside one another, an operator removes the not yet completely filled casing cartons from the roller conveyor  19 , carries them back to the belt conveyor  14  and repositions them there for the next filling operation. Completely filled casing cartons are transported away. This straightforward embodiment offers the advantage that the packing device is no wider than the upstream folding-box adhesive-bonding machine. It can thus also be used for very constricted space conditions. If there is sufficient space in the widthwise direction, use can be made thereof for transporting the casing cartons back automatically, as is illustrated with regard to the embodiment according to  FIG. 2 . 
   In the embodiment of  FIG. 2 , transversely running transporting belts  20  are disposed between the rollers of the roller conveyor  19 , it being possible for the transporting belts to be rendered inactive by being lowered beneath the conveying plane of the roller conveyor  19 , and to be activated by being raised above this conveying plane. The rollers of the roller conveyor  19  extend transversely beyond the filling region to such an extent that, on the ends thereof, casing cartons  2  can be transported back, past the filling location, in the direction counter to the filling direction. Following the roller conveyor  19 , alongside the filling location, is a further roller conveyor  21 , of which the conveying section extends, parallel and in the opposite direction to the conveying sections of the conveyors  14 ,  16 ,  17 , into the region of the start of the belt conveyor  14 , and thus forms the end of the packing device on this side. At this end, the conveying section of the roller conveyor  21  is connected to the start of the belt conveyor  14  via a further, transversely conveying roller conveyor  220 . This makes it possible, for an automated multilayered filling operation, for cartons to be conveyed, revolving or circulating through the filling location a number of times. In this advantageous embodiment, all that is required is for the operator  15  to position empty cartons on the belt conveyor  14  and to remove filled cartons from the roller conveyor  21 . It is also possible for these two manual operations to be automated by the attachment of corresponding conveyors. It is also advantageously possible to place further additional subassemblies along the conveying sections of the conveyors  21  and  22 , for example units by which the casing cartons are set in an upright position and opened, or units for closing the filled cartons. 
   The transition between the folding-box feeder  3 , which is illustrated in  FIG. 9 , and the conveyor  9  is configured as an accumulating and transfer device  50 , of which the parts fastened on the conveyor  9  are illustrated on an enlarged scale in  FIG. 8 . The accumulating and transfer device  50  has the task of collecting a given number of boxes  1  and transferring them in imbricated form, with a pre-set degree of overlapping, to the belts  27 ,  29  of the conveyor  9 . For this purpose, the boxes  1  are conveyed continuously towards the start of the conveyor  9  by the belts  4  of the feeder  3 . 
   The accumulating and transfer configuration  50  includes an imbricating roller  51  which is disposed at the bottom at the start of the conveyor  9  and, at the same time, forms the inlet-side deflecting roller of the bottom conveying belt  29 . The imbricating roller  51  has the task of conveying between the conveying belts  27 ,  29 , respectively, the first box of an assembled stack or pile accumulated in front thereof. The conveying belt  29  which runs around it is guided in a loop to the following deflecting roller  52 , which bounds the conveying section of the conveyor  9 , with the result that the conveying section is interrupted slightly at the bottom. The position of the imbricating roller  51  relative to the deflecting roller  52  determines the degree of overlapping by which the boxes  1  are drawn off from the feeder  3 . The imbricating roller  51  is thus mounted in a pivotable bearing part  53  in order that the degree of imbrication can be adjusted to the desired or nominal value via the position of the imbricating roller  51 . 
   A hold-down bar  54 , which extends counter to the conveying direction of the boxes  1 , is fastened above the imbricating roller  51 , on the conveyor  9 . The hold-down bar  54  has the task of holding the boxes  1 , which are accumulated upright on edge or edgewise, at the top edge thereof. The distance thereof from the belts  4  of the feeder  3  is adjusted to the box width. Together with the ends of the belts  4 , the hold-down bar  54  forms an accumulating section  55 , as can be seen from  FIG. 1 . Because the boxes  1  accumulating in the accumulating section  55  are positioned increasingly vertically as they increase in number, the minimum distance between the top edges of the boxes  1  and the hold-down bar  54  forms a measure of the number of accumulating boxes  1 . In order to measure the length of the accumulating stack of boxes and to control the draw-off speed of the conveying belts  27 ,  29  in dependence thereon, an electromechanical sensor is integrated in the hold-down bar  54  for determining the height of the stack of boxes between the belts  4  and the hold-down bar  54 , and thus the number of accumulating boxes  1 . 
   Fastened at the end of the hold-down bar  54  is an elastic imbricating finger  56  which extends towards the bottom transporting belt  29 . The distance between the imbricating finger  56  and the bottom transporting belt  29  is adjusted to the thickness of the imbricated line of blanks. As the first box  1  of the accumulating stack of boxes is conveyed away, the next-following box  1  is held back by the imbricating finger  56  in order not to be drawn along by the first box  1 . The hold-down bar  54  with the imbricating finger  56  fastened thereon is mounted in a height-adjustable manner, in order that the position thereof may be adapted to different box widths. 
   The positions of the hold-down bar  54 , with the imbricating finger  56 , and of the imbricating roller  51  can preferably be adjusted in a coupled manner with one another, as is illustrated in  FIGS. 6 and 8 . This offers the advantage that a changeover of the accumulating and transfer configuration  50  to a different box format can be carried out very quickly and without involving any great expense outlay. For this purpose, the bearing part  57 , whereon the hold-down bar  54  with the imbricating finger  56  is fastened, and the bearing part  53  of the imbricating roller  51  are connected to one another via levers  58 , which are adjusted jointly by a handwheel  60  via an adjusting rod  59 . The lever mechanism formed by the bearing parts  53 ,  57  and the levers  58  is configured so that the movements of the hold-down bar  54 , with the imbricating finger  56 , and of the imbricating roller  51  are coupled to the necessary extent, with the result that, in the case of a format adjustment, each part assumes the new position thereof. In order for the position of the imbricating roller  51  to be additionally adjustable in relative terms, this roller  51  is fastened so that it is additionally adjustable on the bearing part  53  thereof. The jointly coupled adjustment of the elements makes it possible to automate the adjustment. Instead of the handwheel  60 , use is then made of an adjusting drive, which moves the adjusting rod  59 . 
   The feeder or supply device  3 , which is illustrated in greater detail in  FIG. 9 , includes belts  4  as conveying elements, which extend into the accumulating section  55 , and thus also convey in the direction counter to the accumulating boxes  1 . They are advantageously configured so that the conveying action of the conveying belts  4  is dependent upon the bearing pressure of the boxes  1 , and this dependency can be adjusted in addition. For this purpose, each conveying belt  4 , as is illustrated in the sectional view of  FIG. 10 , is guided between two top guide bars  70 , and rests on a flexible pressure tube  71  which can be subjected to the action of compressed air. Disposed between the flexible pressure tube  71  and the conveying belt  4  is a thin, deformable plate  72  via which the conveying belt  4  can slide with low friction. The conveying belt  4  is guided between the guide rails  70 , in a manner supported by the flexible pressure tube  71 , so that, without being forced downwardly by the weight of the boxes  1  resting thereon, it projects beyond the top surfaces of the guide bars  70 . The belt  4  thus acts upon the undersides of the boxes  1  and conveys the latter further. If the weight of the boxes  1  increases, the conveying belt  4  is then forced downwardly counter to the force of the flexible pressure tube  71 . In this regard, it moves downwardly relative to the top surfaces of the guide rails  70  until the latter are located in a single plane with the top surface of the belt  4 . In this position, the boxes rest on the top surfaces of the rails  70  and are no longer conveyed further by the belt  4 . Depending upon the weight of the boxes  1  resting thereon, it is thus possible for a different conveying force to be established over the conveying length of the belts  4 . The conveying force is very low in the region of the accumulating section  55 , while it is high at the start of the feeder  3  because, thereat, the boxes  1  rest on the belts  4  in a condition wherein they are imbricated at a relatively great distance apart from one another. The change in the conveying action of the belts  4  in dependence upon the weight of the boxes  1  resting thereon can be adjusted via the pressure in the flexible pressure tube  71 . For this purpose, each flexible pressure tube  71  is connected to a compressed-air source  70  via lines  73  and a control valve  74 . 
   The two guide rails  70  and the flexible pressure tube  71  with the conveying belt  4  resting thereon, respectively, extend over the entire conveying section of the feeder  3 . For this purpose, they are disposed between two plate-like side parts  75 , which are screwed to one another and are mounted so that they are adjustable transversely on spindles  76 . The spindles  76  extend transversely to the conveying direction and are mounted, by the ends thereof, in side parts  77  of the framework of the feeder  3 . Two conveying belts  4  are preferably mounted in the aforedescribed manner, at a distance from one another, respectively, and so that they are adjustable transversely, individually, on spindles  76 , and are driven jointly via a tilting shaft  79  connected to a rotary drive  78 . The stop  6 , which is likewise mounted in a transversely adjustable manner, is illustrated partly in section in  FIG. 9 . The boxes  1  are aligned on the stop  6  if they are supplied to the conveying belts  4  at an angle of 90° thereto. Other features which are considered as characteristic for the invention are set forth in the appended claims.