Patent Abstract:
An apparatus for feeding sheet-like articles, such as newspapers, periodicals, and inserts therefor, from a vertical stack of the articles. The stack is supported on a fixed rest  3 , and a sucker arrangement  24  and a pushing away unit  38  are mounted on a load bearing structure  44  which is supported so as to float with the height of the stack. The sucker arrangement  24  includes a pair of suction heads  25  which are mounted for movement between a lowered extended position and a raised retracted position, and the suction heads have suction openings  25   a  which are permanently connected to a source of negative pressure. In operation, the suction heads  25  engage the uppermost one of the articles in the stack, which closes the suction openings  25   a  and causes the suction heads and uppermost article to be lifted. The pushing away unit  38  then engages and laterally moves the article away from the suction heads. The suction openings  25   a  are thereby opened and the heads are then biased to their extended positions in engagement with the next article in the stack. The sequence is then repeated.

Full Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of PCT/CH99/00529, filed Nov. 10, 1999, and designating the United States. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for feeding sheet-like articles, in particular printed products such as, for example, newspapers, periodicals, parts thereof and inserts therefor, from a vertical stack thereof. 
     In a known apparatus of this type (EP-A-0806 391), a sucker arrangement is provided which comprises suction heads which are fitted on a rotor which is driven in rotation. The suction heads, which are connected to a negative-pressure source, are positioned from above on the respectively uppermost printed product of the stack. The printed product are then gripped under the action of the negative pressure acting on the suction opening of a suction head, and are raised off from the stack as the suction head moves further. The sucker arrangement brings the gripped printed product into the active region of a pushing arrangement, which comes to act on an edge of the raised-off printed product. At this point in time, the suction heads are disconnected from the negative-pressure source, as a result of which the gripped printed product is released and pushed away from the stack by the pushing arrangement. 
     The sucker arrangement thus serves only for raising the printed products off from the stack, while the pushing arrangement performs the task of transporting the printed products away. 
     This known apparatus requires a comparatively high level of mechanical outlay in order to control the movement of the suction heads. In addition, control means are necessary for periodically connecting the suction heads to the negative-pressure source and disconnecting them therefrom. 
     Also known are apparatuses which are intended for raising sheet-like articles off from a stack and transporting them away (EP-A-0 585 924 and GB-A-712,337) and have sucker arrangements in which the suction head is guided in a longitudinally displaceable manner in a guide. The suction head is retained in its front, receiving position by means of an elastically deformable restoring element, e.g. a compression spring. If the suction head, with the suction opening connected to the negative-pressure source, is positioned on the uppermost article of the stack, which results in the suction opening being closed, then the suction head automatically moves rearward, counter to the action of the restoring element, into a rear, discharge position. By virtue of this movement of the suction head, the gripped article is raised off from the stack. By virtue of the movement of the sucker arrangement together with the gripped article, the latter is conveyed away from the stack. For the release of the article conveyed away in this manner, the suction head is disconnected from the negative-pressure source. 
     These solutions thus require a control means for connecting the negative-pressure source to the suction opening of the suction heads and disconnecting it therefrom. 
     It is an object of the present invention described above, to provide an apparatus of the type with a relatively straightforward design and control which requires less outlay, and allows a stack to be reduced satisfactorily without the products being adversely affected. 
     SUMMARY OF THE INVENTION 
     The above and other objects and advantages of the present invention are achieved by the provision of an apparatus which comprises a rest for supporting a vertical stack of the articles, a sucker arrangement for lifting the uppermost one of the articles from the stack, and a pushing away mechanism for laterally moving the article which has been lifted from the stack by the sucker arrangement. The sucker arrangement includes at least one suction head which is mounted for movement in a is guide element between a lowered extended position where it engages the uppermost one of the articles in the stack, and a raised retracted position. Also, the suction head has a lower suction opening which is permanently connected to a negative pressure source, and a restoring element is provided for biasing the suction head toward its lowered position. 
     The specific design of the suction head and the particular design of the pushing away mechanism make it possible for the movement of the suction head to be controlled, without the suction opening being connected to the negative pressure source and disconnected therefrom, solely by the gripped sheet-like articles being pushed away from the suction opening. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the subject matter of the invention are explained in more detail hereinbelow with reference to the accompanying drawings, in which, purely schematically: 
     FIG. 1 is a side view of an apparatus for reducing a stack of sheet-like articles which embodies the present invention. 
     FIG. 2 shows, on an enlarged scale and likewise in side view, the structural unit for raising, and pushing the articles away from the stack, 
     FIG. 3 is a view taken in the direction of the arrow A in FIG. 2, of the structural unit shown in FIG. 2, 
     FIG. 4 shows the suction head in longitudinal section, 
     FIGS. 5 to  7  are simplified illustrations of the functioning of the structural unit for raising, and pushing away, the articles from the stack, 
     FIG. 8 is a longitudinal section of another embodiment of the suction head, 
     FIG. 9 is a section along line IX—IX in FIG. 8, and 
     FIGS. 10 and 11 show two possible solutions for charging the stack. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An apparatus  1  for reducing a stack  2  is shown in its entirety in FIG.  1 . The stack  2  is supported on a rest  3  which is arranged at a given, fixed height. In the present exemplary embodiment, the stack  2  comprises printed products  4 , which in this case are folded. These printed products  4  may be newspapers or periodicals and parts thereof or inserts therefor. 
     In order to raise, and to push away, the respectively uppermost printed product  4  from the stack  2 , a raising and pushing off unit is provided, the unit being designated  5  and being shown on an enlarged scale in FIGS. 2 and 3. This raising and pushing-off unit  5  is fastened on a transverse carrier  6  which is connected to two connecting carriers  7 ,  8 , which are each arranged adjacent the sides of the stack  2 . 
     The two connecting carriers  7 ,  8  are connected to a carriage  9  which is guided in a schematically indicated longitudinal guide  10  such that it can be displaced longitudinally in the direction of the arrow B, i.e. such that it can be ajusted in height. Guide rollers  11  are provided on the carriage  9  and are supported on the longitudinal guide  10 . Acting on the carriage  9  is a balance weight  12  which is connected to the carriage  9  by means of a drawing element  13 . The location at which the drawing element  13  is fastened on the carriage  9  is designated  13   a . The drawing element  13  is guided over a stationary, rotatably mounted deflecting roller  14 . Instead of the balance weight  12 , it is also possible to use a cylinder/piston unit or a pneumatic spring. 
     A removal conveyor  15  is provided in order to remove the printed products  4  raised from the stack  2 . The conveyor is designed as a rocker and, in the present case, is formed by a belt conveyor. The latter has one or more conveying belts  16  which are arranged one beside the other and guided over deflecting rollers  17  and  18 . The deflecting roller  18  is mounted in the carriage  9  by way of its rotary spindle  18   a  and thus moves along with the lifting movement of the carriage  9 . The other deflecting roller  17  is mounted in two bearing arms  19  by way of its rotary spindle  17   a , only one bearing arm being visible in FIG.  1 . The bearing arms  19  are seated on a bearing spindle  20 , which is mounted rotatably in a framework  21  (only illustrated in part). A schematically indicated drive motor  22  serves for driving the belt conveyor  15  in the direction of the arrow D. 
     As can be seen from FIG. 1, the printed products  4  raised from the stack  2  are conveyed away in an imbricated formation S in which each printed product  4  rests on the following printed product. The trailing edges  4   a  of the printed products  4 , which in the present case are the folded edges, are thus exposed in the imbricated formation S. 
     In FIG. 1, the carriage  9  is shown in the top end position. The bottom end position of the carriage  9  is indicated by chain-dotted lines and designated  9 ′. In this bottom end position of the carriage  9 , the guide rollers and the balance weight assume the position indicated at  11 ′ and  12 ′, respectively. The possible displacement travel of the carriage  9  is specified by the arrow C. In this bottom end position of the carriage  9 , the removal conveyor  15  and the carriers  6 ,  7  and  8  also assume a bottom position, which is likewise depicted by chain-dotted lines in FIG.  1 . 
     The construction of the raising and pushing off unit will now be explained in more detail hereinbelow with reference to FIGS. 2,  3  and  4 . 
     This raising and pushing off unit  5  has a sucker arrangement  24  containing two suction heads  25  spaced apart one beside the other. Each suction head  25  has a suction opening  25   a  (FIG.  4 ). The suction heads  25  are guided in a longitudinal guide  26  and can be displaced in the direction of their longitudinal axis. The hollow cylindrical longitudinal guides  26  each have likewise hollow cylindrical connection stubs  27  (FIG. 3) connected to them. Connected to the connection stubs  27  are connecting lines  28 , which lead to a negative pressure source (not illustrated specifically). Each suction opening  25 a is thus in permanent connection with the negative pressure source via the longitudinal guide  26 , the connection stub  27  and the connecting line  28 . 
     Arranged between each suction head  25  and the fixed connection stub  27  is a compression spring  29 , which biases the suction head  25  toward its extended, receiving position, which is shown on the left-hand side in FIG.  3  and in FIG.  4 . In order to prevent the suction heads  25  from being forced out of the longitudinal guides  26 , an annular shoulder  30  is formed (FIG. 4) on each longitudinal guide  26 . The annular shoulder interacts with an annular protrusion  31  on the suction head  25  in the extended end position of the suction head  25 . 
     Each longitudinal guide  26  is fastened on a securing element  32 , which is connected to a connecting part  33 . The latter is fastened on a bearing part  34 , which is connected to a longitudinal carrier  35 . A connecting element  36  connects the longitudinal carrier  35  to a load bearing column  37 , which is fastened on the transverse carrier  6 . 
     The raising and pushing off unit  5  also contains two pushing away units  38 , which are likewise spaced apart one beside the other. Each pushing away unit  38  is located in the vicinity of a suction nozzle  25 , as FIG. 3 shows. Each pushing away unit  38  has a number of pushing away protrusions  39 , which are fastened at regular intervals on an endless conveying chain  40 . Each of these conveying chains  40  is guided over deflecting wheels  41  and  42 . As is shown, but not described in any more detail, the deflecting wheels  41 ,  42  are fastened rotatably in a load bearing framework  44  formed by the already mentioned structural elements  34 - 37  and a fastening linkage  43  (FIG.  2 ). A deflecting wheel of each pushing away unit  38 , e.g. the deflecting wheel  42 , is driven in the clockwise direction via a drive (not illustrated), which results in the pushing away protrusions  39  being moved in the direction of the arrow F. 
     The raising and pushing off unit  5  also has two holding down elements  46  spaced apart one beside the other. Each holding down element  46  is fastened on a securing means  47  (FIG.  2 ), which is seated in a rotationally fixed manner on a shaft  48 . This shaft  48  is mounted rotatably in a mounting part  49 , which is fastened on a carrier  50  belonging to the fastening linkage  43 . Connected to the shaft  48  is a lever  51  which engages in an elongate guide slot  53  in a control lever  54  by way of a bolt  52 . The control lever  54  is seated on a shaft  55 , which is mounted rotatably in a load bearing framework  44  in a manner which will not be described in any more detail. A control lever  56  is fixed to the shaft  55 . The control lever  56  interacts with a control element  58  which is fastened on the common shaft  57  of the deflecting wheels  41 , and thus rotates along with the deflecting wheels  41 , and has projecting control fingers  59  (FIG.  2 ). In the present case, three control fingers  59  are provided, these acting on the control lever  56 , and raising the same, periodically in each case. The action of raising the control lever  56  results in the control lever  54  being pivoted into the position which is shown by chain-dotted lines in FIG.  2  and is designated  54 ′. By virtue of the movement of the control lever  54 , the lever  51  is pivoted into the position designated  51 ′, which results in the holding-down elements  46  being pivoted rearward into the position designated  46 ′ in FIG.  2 . 
     The raising and pushing-off unit  5  also has a supporting arrangement  60 , which serves for supporting the load-bearing framework  44  and the load-bearing structure, formed by the carriers  6 ,  7  and  8 , on the stack  2 . This supporting arrangement  60  contains a transverse carrier  61 , which is supported on the longitudinal carrier  35  of the load-bearing framework  44  via a connecting element  62 . The connecting element  62  is mounted pivotably on the longitudinal carrier  35 . It is thus possible for the connecting element  62  and the transverse carrier  61  to execute an oscillating movement about the longitudinal axis of the longitudinal carrier  35 . This pivoting or oscillating movement is indicated by the arrow G in FIG.  3 . 
     Fastened on the transverse carrier  61  are connecting elements  63 ,  64  in which load-bearing bars  65  and  66  are respectively retained, the longitudinal axes of the bars running essentially at right angles to the longitudinal axis of the transverse carrier  61 . A supporting wheel  67 ,  68  is mounted rotatably at the bottom, free end of each load-bearing bar  65 ,  66 , respectively. These supporting wheels  67 ,  68  rest on the stack in the region of the side edges  2   a ,  2   b , in the corners of the stack  2 . As can be seen from FIG. 2 in particular, the supporting wheels  67 ,  68  are positioned obliquely. This means that the axes of rotation  67   a ,  68   a  of the supporting wheels  67 ,  68  run transversely, that is to say neither parallel nor at right angles, to the side surfaces  2   a ,  2   b ,  2   c  of the stack  2 . 
     It can be gathered from the description of the construction of the apparatus  1  for reducing the stack  2  which has been provided to this point that the raising and pushing-off unit  5 , which is supported on the stack  2  via the supporting arrangement  60 , follows the stack  2  as the latter is being reduced, which has yet to be described. The load bearing structure, which is formed by the carriers  6 ,  7 ,  8 , is thus lowered with the carriage  9 , guided in the guide  10 , the load bearing framework  44  and the components fastened on the latter, as the stack  2  is being reduced. As FIG. 1 shows, the removal conveyor  15  also moves along with this lowering movement of the structural unit  5  and of the carriage  9 , the bearing arms  19  thus pivoting in the direction of the arrow E. 
     The functioning of the raising and pushing off unit  5  will now be described hereinbelow with reference, in particular, to FIGS. 2 to  7 . 
     The suction heads  25  are fixed in height in relation to the supporting wheels  67 ,  68  such that, in their extended, receiving position, the suction heads  25  rest on the respectively uppermost printed product  4 ′ of the stack  2  by way of the suction opening  25   a , as is shown on the left-hand side in FIG.  3  and in FIG.  5 . In this position of the suction heads  25 , the suction opening  25   a  thereof, which is connected permanently to the negative pressure source, is closed by the uppermost printed product  4 ′. A negative pressure is then produced in the interior of the suction heads  25 . This results in the suction heads  25  being raised together with the gripped printed product  4 ′ and moving, counter to the action of the compression springs  29 , from the extended, receiving position into the retracted position. This means that the uppermost printed product  4 ′ is lifted from the stack  2  in the region of its trailing edge  4   a  and moved into the movement path of the pushing away protrusions  39  (FIG. 1, FIG. 2, FIG. 3, right-hand side, FIG.  6 ). 
     The next pushing away protrusion  39  comes to act on the raised printed product  4 ′ in the region of its trailing edge  4   a  and, as it moves further in the direction of the arrow F, pushes the uppermost printed product  4 ′ away from the stack  2 , as FIGS. 1,  6  and  7  show. At the beginning of the displacement path of the uppermost printed product  4 ′, the suction openings  25   a  of the suction heads  25  are still closed (FIG.  6 ), but are released to an increasing extent. As soon as the gripped printed product  41  has been pushed away in its entirety from the suction opening  25   a  of the suction heads  25 , the suction heads  25  return, under the action of the compression spring  29 , into their front, receiving position, in which, as has been mentioned, they come to rest on the next printed product  4  by way of their suction openings  25   a . As a result, the above described lifting operation begins anew. 
     The pushing-away protrusions  39  of the pushing away units  38  move the printed products  4  into the active region of the removal conveyor  15 , by means of which the printed products  4  pushed away from the stack  2  are removed in an imbricated formation S (FIG.  1 ). It should be pointed out here that it is, of course, also possible for the spacings between the pushing away protrusions  39  to be selected such that the pushed off printed products  4 , rather than overlapping on the removal conveyor  15  and thus being conveyed away in an imbricated formation S, are conveyed away one behind the other. It is possible to adjust the phase position of the pushing away protrusions  39  in relation to the lifted printed products  4 , as a result of which it is possible to coordinate the point in time at which the printed products  4  are pushed away. 
     As FIGS. 2 and 3 show, the holding down elements  46  are located in a rear, standby position when the suction heads  25  assume their front, receiving position and rest on the uppermost printed product  4 ′. This standby position is depicted by chain-dotted lines, and designated  46 ′ in FIG.  2  and is illustrated on the left-hand side in FIG.  3 . As the suction heads  25  move away from the stack  2  in the manner described, the holding down elements  46 , controlled by the control fingers  59 , the control lever  54  and the lever  51 , are moved against the top side of the stack  2 . They come to rest on top of the stack  2  in an active position in the region of the trailing edge  4   a  of the printed products  4  as soon as the uppermost printed product  4 ′ has been raised from the stack  2  by the suction heads  25 , but before the uppermost printed product  4 ′ has been pushed away. This active position of the holding down elements  46  is illustrated by solid lines in FIG.  2  and on the right-hand side in FIG.  3 . 
     The holding down elements  46 , which press on the stack  2  from above in their active position, are intended to ensure that, as the previously raised printed product  4 ′ is being pushed away by the pushing away protrusions  39 , the printed product  4  located therebeneath is not carried along with it. 
     As soon as the control lever  56  runs off the control finger  59 , the holding down elements  46  are pivoted back into their retracted, standby position. 
     As has been described, the suction heads  25  are moved out of their retracted, discharge position into the extended, receiving position again as soon as their suction openings  25   a  have been released. This makes it possible to reduce the period of time taken by an operating cycle of the suction heads  25  with the suction openings  25   a  being of the smallest possible dimension in the pushing-off direction F. In order nevertheless to achieve a sufficiently large suction opening  25   a , it is the case in a preferred embodiment that the suction opening  25   a ′ is designed in the manner of a longitudinal slot, as is illustrated in FIGS. 8 and 9. The suction opening  25   a ′, designed as a slot-type nozzle, extends here in a direction which forms an angle of approximately 90° with the pushing-off direction F. 
     Two variants for charging the stack  2  which is to be reduced will be explained with reference to FIGS. 10 and 11. 
     In the embodiment according to FIG. 10, a new stack  2 ′ is moved in beneath the rest  3 , on which the stack  2  is located. Once the stack  2  has been reduced almost completely, then the stack  2 ′ located therebeneath can be pushed upward in a manner which is not illustrated specifically. The stack  2 ′ can be pushed up in this way either during a break in the stack-reducing operation or as the stack  2  is being reduced. The rests  3 ,  3 ′ alternately perform the stack supporting function. 
     In FIG. 10,  2 ″ designates a further stack which, once the stack  2 ′ has been pushed up into the stack reducing position, is displaced to the location of said stack  2 ′. 
     In the embodiment which is shown in FIG. 11, new printed products  4  are constantly fed to the stack  2  from beneath, the printed products being fed in an imbricated formation S′, in the direction of the arrow H, by means of a feed conveyor  70 . In the imbricated formation S′, each printed product  4  rests on the following printed product in each case. The charging of the stack  2  thus takes place in a manner similar to that for the apparatus according to EP-A-0 806 391, mentioned in the introduction, the difference being that the feed conveyor  70 , rather than having to be designed as a rocker, may be arranged such that its position cannot be changed. This is possible because, on account of being supported on the top side of the stack and being mounted in a moveable manner, the raising and pushing off unit  5  is capable of following the changing level of the top side of the stack  2 . The feed conveyor  70  performs the function of the fixed height rest  3  of the apparatus  1  shown in FIGS. 1 and 10. 
     A considerable advantage of the apparatus according to the invention can also be gathered from what has been said above. This is because the apparatus according to the invention does not require the height of the rest  3  or of the feed conveyor  70  to be controlled such that the top side of the stack  2  is always at the same level, because the raising and pushing off unit  5  is capable of following the changing height of the top side of the stack  2 . 
     It goes without saying that various components, in particular the pushing away units  38  and the holding down elements  46  and the drive thereof, may also be designed in a manner other than that which has been described and shown. It is possible, for example, for the printed products  4  lifted by the suction arrangement  24  to be pushed away by means of a pushing arrangement as has been described in the previously mentioned EP-A-0 806 391. 
     In the exemplary embodiments shown, the printed product  4  secured by the suction heads  25  in each case is pushed away from the suction heads  25  by the pushing away protrusions  39  of the pushing away units  38  in order to release the suction opening  25   a  of the suction heads  25 . In other words, the pushing away protrusions  39  move past the fixed suction heads  25 . 
     In order for the gripped printed products  4  to be pushed away from the suction heads  25 , it is also possible, with otherwise the same functioning of the suction heads  25 , for the latter to be moved, together with the gripped printed product  4 , against stationary stops. The gripped printed product  4  positioned against these stops is prevented from moving further and the suction heads  25  slide off the printed product  4  as they move further, which results in the suction openings  25   a  being released. The suction heads  25  are then moved away from the stops again back into the starting position, in order to grip the next printed product. This requires a corresponding control means and extends the duration of an operating cycle.

Technology Classification (CPC): 1