Abstract:
An indexible turret delivers successive stacks of a series of stacks of overlapping paper sheets to an adhesive applying or coating station where the elongated spine of a freshly delivered stack assumes a predetermined position. An elongated carriage is movable longitudinally of the spine at the coating station and carries two mirror symmetrical nozzles one of which is activated to supply a coat of adhesive to the spine at the coating station while the carriage moves in one direction and the other of which is activated to apply a coat of adhesive to the spine of the next stack of the series while the carriage moves in the opposite direction. The nozzles have elongated slots extending transversely of the spine at the coating station, and each nozzle is mounted in a discrete frame and is adjustable in and/or with such frame transversely of as well as toward and away from the spine at the coating station. The frames carry pairs of roller followers which track the exposed sides of pairs of clamping elements forming part of the turret and serving to engage the stacks adjacent to their spines.

Description:
CROSS-REFERENCE TO RELATED CASES 
     This application claims the priority of German patent application Serial No. 197 56 958.7 filed Dec. 20, 1987. The disclosure of this German patent application, as well as that of each other patent application and/or patent mentioned in the specification of the present application, is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to improvements in apparatus for applying coats or films of an adhesive to selected sides or surfaces (normally to the spines) of stacks, blocks or piles consisting of or comprising overlying or overlapping sheets, panels and/or plates of paper, cardboard or the like. For the sake of brevity and simplicity, the accumulations of sheet-like commodities will be referred to as stacks, and those selected elongated sides or surfaces of the stacks which are to be provided with films or coats of a suitable adhesive will be referred to as spines. Finished products which are obtained by resorting to the apparatus of the present invention can constitute legal pads or other types of stationery products, portions of books or the like. 
     It is well known to establish more or less permanent connections between selected edges of overlapping paper sheets or the like by providing such edges with a coat or film of a suitable adhesive. Reference may be had, for example, to published German patent application No. 34 20 875 A1 which discloses an apparatus wherein the means for applying a coat of adhesive to the spine of a stack of paper sheets or the like comprises a series of successive adhesive-applying rollers. Since the rollers must be caused to bear upon the spine of the stack which is located at the coating station, such apparatus cannot invariably ensure the application of an adhesive coat or layer having an optimum width. Moreover, such apparatus cannot apply to a spine an accurately selected quantity of adhesive; this can entail pronounced changes in the thickness and strength of the applied adhesive coat. 
     OBJECTS OF THE INVENTION 
     An object of the invention is to provide an apparatus which constitutes a pronounced improvement over the apparatus disclosed in the aforementioned published German patent application Serial No. 34 20 875 A1. 
     Another object of the invention is to provide an apparatus which can provide the spines of a short or long series of successive stacks of paper sheets or the like with adhesive films, layers or coats of optimum width. 
     A further object of the invention is to provide an apparatus which can ensure a predictable and optimal distribution of adhesive in the longitudinal and/or in the transverse direction of the spine of each of a short or long series of stacks of paper sheets or the like. 
     An additional object of the invention is to provide the improved apparatus with novel adhesive applying and distributing means. 
     Still another object of the invention is to provide an apparatus which can apply highly satisfactory coats or films of adhesive to the spines of large numbers of stacks per unit of time. 
     A further object of the invention is to provide an apparatus which can be readily and accurately adjusted to apply highly satisfactory coats or films of adhesive to relatively wide, relatively narrow, relatively long and/or relatively short spines of stacked paper sheets or the like. 
     Another object of the invention is to provide an apparatus which can properly treat stacks which consist of or contain relatively soft, relatively, hard, relatively stiff, readily flexible and/or other sheets with the same or at least satisfactory degree of facility and predicability. 
     An additional object of the invention is to provide a novel and improved conveyor for delivery of successive stacks of a series of stacks to the adhesive applying or coting station. 
     Still another object of the invention is to provide the above outlined apparatus with novel and improved means for supporting, advancing, adjusting and/or otherwise manipulating the adhesive applying implement or implements. 
     A further object of the invention is to provide a novel and improved method of applying films or coats of a flowable adhesive substance to the spines of stacked paper sheets or the like in such a way that the applied adhesive is prevented from contacting any and all surfaces other than the spines of the stacks. 
     Another object of the instant invention is to provide a series of stationery products or analogous products which are obtained or at least partially finished by resorting to the above outlined method and to the above outlined apparatus. 
     SUMMARY OF THE INVENTION 
     One feature of the present invention resides in the provision of an apparatus for applying coats of a suitable adhesive to selected elongated sides of a series of successive stacks of overlapping sheets at an adhesive applying or coating station. The improved apparatus comprises intermittently operated conveyor means for delivering successive stacks of the series to and for temporarily maintaining the thus delivered stacks at the coating station so that the selected elongated side of the stack at the coating station assumes a predetermined position and orientation, and means for applying a film or layer or coat of adhesive to the selected elongated side of the stack at the coating station. The means for applying comprises at least one adhesive discharging nozzle and means for moving the at least one nozzle longitudinally of and parallel to the entire selected elongated side of the stack at the coating station. 
     The at least one nozzle is preferably provided with a slot-shaped adhesive discharging orifice having a length which at least approximates the width of the selected elongated side of the stack at the coating station. The orifice extends transversely of such elongated side. 
     The apparatus preferably further comprises means for shifting the at least one nozzle between an operative position in which the nozzle can discharge adhesive against the selected elongated side of the stack at the coating station and an inoperative position in which the nozzle is spaced apart from the selected elongated side of the stack at the coating station. 
     Still further, the apparatus preferably comprises means for adjusting the at least one nozzle transversely of the selected elongated side of the stack at the coating station. The means for moving the at least one nozzle can comprise a frame which is movable longitudinally of the selected elongated side of the stack at the coating station, and the aforementioned means for adjusting can comprise a nozzle holder which is shiftable in the frame transversely of the selected elongated side of the stack at the coating station, and means for shifting the nozzle holder. 
     The conveyor means can comprise pairs of clamping elements which are arranged to engage the stacks adjacent to the respective selected elongated sides. The clamping elements are preferably provided with exposed surfaces which extend longitudinally of the selected elongated sides of the stacks being engaged by the clamping elements, and the moving means of such apparatus can comprise followers arranged to track the exposed surfaces of clamping elements which engage the stack at the coating station. Such moving means preferably further comprises the aforementioned frame which is movable longitudinally of the selected elongated side of the stack at the coating station and has elastic portions which are deformable transversely of the selected elongated side of the stack at the coating station. The followers can be mounted on or in the frame and each such follower is arranged to track the exposed surface of one of the two clamping elements for the stack at the coating station. The followers can include or constitute rollers. The arrangement can be such that one of the followers is rotatable relative to the frame and another follower is movable toward and away from the one follower transversely of the selected elongated side of the stack at the coating station. Still further, the moving means can comprise means (e.g., a fluid-operated or a resilient device) for yieldably urging the other follower toward the one follower. 
     In accordance with a presently preferred embodiment, the conveyor means comprises a turret indexible about an axis which is at least substantially parallel to the selected elongated side of the stack at the coating station. The turret has a plurality of axially parallel peripheral receptacles for portions of stacks, and each such receptacle includes a pair of clamping elements which engage the stack in the respective receptacle adjacent the selected elongated side of such stack. The axis of the turret is or can be at least substantially horizontal, and the coating station can be disposed at a level below such axis. 
     As already mentioned hereinbefore, the selected elongated sides can constitute elongated spines of the respective stacks, and the means for applying can comprise a plurality of adhesive discharging nozzles. The means for moving can comprise a carriage which is movable longitudinally of the spine at the coating station in a first direction and in a second direction counter to the first direction. As a rule, or at least in many instances, the nozzles of the aforementioned plurality of nozzles include first and second nozzles which are at least substantial mirror images of each other with reference to a plane extending at right angles to the aforementioned first and second directions and located between the two nozzles. 
     Each nozzle can have an elongated slot-shaped adhesive discharging orifice of a length at least approximating the width of the spines, and such orifices extend transversely of the spine on the stack at the coating station. 
     The nozzles are or can be activatable and deactivatable independently of each other to respectively discharge and interrupt the discharging of adhesive. The first nozzle is activated and the second nozzle is deactivated in response to movement of the carriage in the first direction, and the second nozzle is activated and the first nozzle is deactivated in response to movement of the carriage in the second direction. 
     The just described apparatus preferably further comprises means for shifting the first and second nozzles independently of each other between operative and inoperative positions in which the respective nozzle contacts and is spaced apart from the spine of the stack at the coating station. 
     The moving means preferably further comprises a discrete frame or support for each of the plurality of nozzles; the frames are supported by and they are shiftable relative to the carriage. Such moving means can further comprise means for shifting each of the frames relative to the carriage between a first and a second position in which the respective nozzle is ready to apply adhesive to and is spaced apart from the spine of the stack at the coating station. The nozzles are or can be adjustable in the respective frames transversely of the spine of the stack at the coating station, and the means for applying can further comprise means for adjusting the nozzles relative to the respective frames. Such adjusting means can comprise a discrete nozzle holder which is shiftably mounted in each of the frames for movement transversely of the spine of the stack at the coating station, and means for shifting the nozzle holders relative to the respective frames. 
     As already mentioned hereinbefore, the conveyor means can comprise pairs of clamping elements serving to engage the stacks adjacent the respective spines. Such clamping elements are preferably provided with exposed surfaces extending longitudinally of the spines of the stacks being engaged by the clamping elements, and the moving means of such apparatus preferably further comprises followers serving to track the exposed surfaces of clamping elements which engage the stack at the coating station. The aforementioned discrete frames are mounted on and are movable with the carriage and preferably have elastic portions which are deformable transversely of the spine of the stack at the coating station. The followers include pairs of followers carried by the frames, and each follower of each such pair serves to track the exposed surface of a different one of the clamping elements which engage the stack at the coating station. 
     The followers can include rollers and one roller of each pair is rotatable relative to the respective frame; the other roller of each pair is movable toward and away from the one roller of the respective pair transversely of the spine of the stack at the coating station. The means for applying can further include means for yieldably urging the other roller of each pair toward the one roller of the respective pair. 
     As already explained hereinbefore, a presently preferred conveyor means comprises a turret which is indexible about an axis that is at least substantially parallel to the spine of the stack at the coating station; the turret has a plurality of axially parallel peripheral receptacles for portions of stacks, and each receptacle includes a pair of clamping elements which engage the stack in the respective receptacle adjacent the spine of such stack. The axis of the turret is or can. be at least substantially horizontal, and the coating station is or can be installed at a level below such axis. 
    
    
     The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its contruction and the modes of assembling, installing and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat schematic side elevational view of an apparatus which embodies one form of the invention; 
     FIG. 2 is a plan view of the apparatus which is shown in FIG. 1; and 
     FIG. 3 is a somewhat schematic transverse vertical sectional view substantially as seen in the direction of arrows from the line A—A in FIG.  1 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The conveyor means of the apparatus which is shown in FIGS. 1 to  3  comprises a turret  3  (a portion of such turret is indicated in FIG. 3 by dot-dash lines) which is indexible about a horizontal axis and is provided with an array of axially parallel peripheral receptacles each flanked by two elongated bar- or strip-shaped clamping elements or jaws  6  which engage the stacks  2  of paper sheets or the like in such a way that the selected elongated sides or surfaces  1  (hereinafter called spines for short) remain accessible at the under-side (namely at the six o&#39;clock position) of the turret  3 , and more specifically at an adhesive applying or coating station  4 . As can be seen in each of FIGS. 1 to  3 , the coating station  4  is located at a level below the axis of the turret  3 . 
     A similar turret is disclosed in published German patent application Serial No. 33 01 032 A1 corresponding to U.S. Pat. No. 4,500,241 the disclosure of which is incorporated herein by reference. The conveyor means further comprises customary means for indexing the turret  3  in stepwise fashion so as to move successive stacks  2  of a series of such stacks to the coating station  4  and to maintain each stack at such station for an interval of time which is required to complete the application of a film or coat of adhesive to the spine  1  at the six o&#39;clock position of the turret. As can be seen in FIGS. 1 and 3, the spine  1  at the coating station  4  is located at a level slightly below the undersides of the respective clamping elements  6 . FIG. 1 shows the spine  1  at the station  4  and one of the clamping elements  6  by dot-dash lines. The clamping elements  6  have exposed external surfaces  38  (shown by solid lines in FIG.  3  and by dot-dash lines in FIG. 2) which face away from the stacks  2  between them and serve to guide pairs of rotary guide elements  36 ,  37  (in the form of rollers) in a manner and for the purposes as will be fully described hereinafter. 
     The station  4  is located at a level above a straight elongated guide  7  (e.g., a rail) defining a straight elongated path which is parallel to the axis of the turret  3  and to the spine  1  of the stack  2  at the coating station  4 . The guide  7  determines the movements of an elongated reciprocable carriage  8 . The latter is movable in directions to the left and to the right (see the double-headed arrow  44  in FIG. 1) and supports two adhesive applying units  9 ,  11  which respectively comprise nozzles  12 ,  13 . These nozzles are mirror images of each other with reference to a plane (see the plane A—A in FIG. 1) which is located between the two nozzles and is normal to the spine  1  of the stack  2  at the coating station  4 . Since the unit  11  is identical with the unit  9  (except that it is installed as a mirror image of the unit  9 ), only the unit  9  will be described in full detail. 
     The adhesive applying unit  9  comprises a frame or support  14  which shares the movements of the carriage  8  in directions indicated by the arrow  44  and is pivotable relative to the carriage about the axis of a shaft  16  mounted on a pedestal or base  17  affixed to or forming part of the carriage. The frame  14  carries the nozzle  12  which is remote from the shaft  16  and is movable relative to the carriage  8  along an arcuate path between an operative (adhesive applying) position shown in the left-hand half of FIG. 1, and an inoperative position in which its elongated slot-shaped orifice is spaced apart from the spine  1  of the stack  2  at the coating station  4 . The right-hand nozzle  13  (of the unit  11 ) of FIG. 1 is shown in its inoperative or retracted position. The means for shifting the nozzle  12  between its operative and inoperative positions comprises an actuating device  33  having a mobile pusher  34  which can pivot the frame  14  clockwise (as viewed in FIG. 1) in order to move the nozzle  12  to the inoperative position. A resilient element  32  (such as a coil spring) is provided to permanently urge the nozzle  12  to its operative position (by biasing the frame  14  in a counterclockwise direction, as viewed in FIG.  1 ), e.g., to an operative position which is determined by the actuating device  33 . The illustrated resilient element  32  reacts against the carriage  8  and bears upon a head  29  of the nozzle  12 . The actuating device  33  is or can be coupled with the reversible motor for the carriage  8  in such a way that the nozzle  12  is operative (under the bias of the spring  32 ) while the carriage  8  moves in one direction but that the nozzle  12  is inoperative (in response to clockwise pivoting of the frame  14  by the pusher  34 ) when the carriage moves in the opposite direction. 
     The frame  14  comprises two sidewalls  19  which resemble bell crank levers and are elastically deformable toward and away from the observer of FIG. 1, i.e., transversely of the longitudinal direction of the spine  1  of the stack  2  at the coating station  4 . Those portions of the sidewalls  19  which are adjacent the actuating device  33  are connected to each other by a plate-like connector  18  which can be engaged and moved by the pusher  34  when the frame  14  is to be pivoted clockwise (as viewed in FIG.  1 ), namely to move the nozzle  12  to its retracted or inoperative position. The sidewalls  19  are or can be pivotally mounted on the pedestal  17  of the carriage  8 . 
     The nozzle  12  is mounted in a substantially U-shaped holder or carrier  21  having a bottom wall  22  and two sidewalls  23 ,  24  normal to the wall  22  and flanked by the elastically deformable sidewalls  19  of the frame  14 . The bottom wall  22  supports an aligning slide  26  which is movable transversely of the spine  1  of the stack  2  at the coating station  4 . The slide  26  supports a nozzle holder  28  which, in turn, carries the aforementioned head  29  of the nozzle  12 . The means for adjusting the slide  26  (and hence the nozzle  12 ) transversely of the spine  1  of the stack  2  at the station  4  comprises a manually operated or a motor-driven device  27  which enables an operator or an automated adjusting system to move the elongated slot-shaped orifice in the head  29  of the nozzle  12  to an optimum position for the application of a coat or film of adhesive to the spine  1  at the station  4 . Such application of adhesive takes place while the spring  32  is free to maintain the nozzle  12  in the operative position and while the carriage  8  is in the process of moving the frame  14  in one of the directions indicated by the arrow  44 . The arrow  46  (shown in FIG. 1) indicates the directions of movement of the nozzle  12  between its operative (adhesive-discharging) and inoperative (retracted) positions. 
     A conduit  31  (e.g., in the form of a flexible hose) is provided to connect the head  29  of the nozzle  12  with a suitable source (not shown) of adhesive, e.g., with a refillable pot wherein the adhesive is maintained at a requisite pressure or which discharges adhesive by gravity flow. 
     The roller followers  36 ,  37  are mounted on the frame  14  in such a way that they can track the exposed surfaces  38  of the two clamping elements  6  at the coating station  4  while the carriage  8  is caused to move along the guide  7  in one of the directions indicated by the arrow  44 . The roller followers cooperate with the surfaces  38  to ensure that the orifice of the nozzle  12  is compelled to travel along the entire spine  1  of the stack  2  at the station  4  in such position that the spine is coated across its entire width but that the adhesive issuing from the slot-shaped orifice of the nozzle  12  cannot contaminate the sides of the stack  2  and/or portions of the clamping elements  6  at the coating station  4 . 
     The roller follower  36  is rotatably mounted on a bearing member or block  39  which is fixedly secured to the sidewall  23  of the U-shaped member  21 . The aforementioned adjusting device  27  can move the nozzle holder  28  and the slide  26  transversely of the U-shaped member  21  so as to locate the nozzle  12  in an optimum position relative to the roller follower  36 , i.e., relative to the spine  1  at the coating station  4 . 
     The other roller follower  37  on the frame  14  is mounted in a frame-like element  41  which is carried by the U-shaped member  21 , and this roller follower is movable transversely of the spine  1  at the station  4 , i.e., toward and away from the roller follower  36 . The means  43  for yieldably urging the roller follower  37  toward the roller follower  36  comprises a biasing arrangement  42  (e.g., a pneumatic accumulator and/or one or more resilient elements). The extent of movability of the roller follower  37  toward the roller follower  36  is limited by the exposed surface  38  of the clamping element  6  which confronts the roller follower  37  at the coating station  4 . The biasing arrangement  42  is or can be carried by the frame-like element  41 . 
     FIG. 1 merely identifies the compression spring  32   a  (analogous to the aforementioned spring  32  of the unit  9 ) and the actuating means  33   a  of the unit  11 . 
     The mode of operation of the improved adhesive applying apparatus which is shown in FIGS. 1 to  3  is as follows: 
     The first step includes orienting the nozzles  12 ,  13  relative to the respective roller followers  36  (by the coresponding actuating means  33 ,  33   a ). Furthermore, and if the nozzle  12  is to discharge a layer of adhesive, the device  27  is caused to adjust (if necessary) the position of the aligning slide  26 , of the nozzle holder  28  and the head  29  of the nozzle  12  transversely of the spine  1  at the coating station  4 . Such adjustment takes place relative to the U-shaped member  21  and is completed when the distance of the slot-shaped orifice of the nozzle  12  from the roller follower  36  matches the distance of such roller follower and of the corresponding exposed surface  38  from the spine  1  at the station  4 . 
     Conventionally, the length of a slot-shaped orifice in a nozzle will slightly exceed the width of a spine  1  to be coated with a layer of adhesive paste because the layer of adhesive issuing from such orifice undergoes a certain constriction (narrowing), normally during actual application to the spine. This can be seen in FIG. 2 wherein the spine  1  at the station  4  extends between the two dot-dash lines  15  and the distance between such lines is slightly less than the length of he slot-shaped orifices of the nozzles  12  and  13 . 
     Since the roller follower  36  is not movable transversely of the station  4 , and since this roller follower tracks the exposed surface  38  of the adjacent (then stationary) clamping element  6 , a positioning of the nozzle  12  at a desired distance from the exposed surface  38  being tracked by the roller follower  36  is tantamount to locating the nozzle  12  in a predetermined position relative to the edges (lines  15  in FIG. 2) of the spine  1  at the station  4 . The just discussed feature renders it possible to properly position the orifice of the nozzle  12  for movement along the full length of the spine  1  at the coating station  4  even if that side of the stack  2  at the station  4  which is nearer to the roller follower  36  comprises one or more soft and/or thin sheets of paper or the like. It has been found that the applied adhesive can reliably bond the soft and/or thin outer sheet(s) to the neighboring sheet(s) without risking a contamination of the front and/or rear side of the stack by an eventual surplus of adhesive. 
     At the start of an adhesive applying operation, the carriage  8  is held in one of two end positions in each of which the units  9 ,  11  and their frames  14  are located outside of the coating station  4 , i.e., the carriage  8  and the parts which are mounted thereon do not interfere with indexing of the turret  3  to a new position in which an untreated stack  2  is held between the respective clamping elements  6  at the station  4 . Once the turret  3  is brought to a halt, one of the nozzles  12 ,  13  (such as the nozzle  12 ) is moved from the inoperative position (FIG. 1 shows the nozzle  13  in the inoperative position and the nozzle  12  in the operative position). Such movement is effected (as far as the nozzle  12  is concerned) by the spring  32  in one of the directions indicated by the double-headed arrow  46 . At such time, the actuating means  33  and its pusher  34  permit the frame  14  for the nozzle  12  to pivot in a counterclockwise direction. At the same time, the nozzle  12  is activated. e.g., in response to opening of a valve in or for the hose  31  so that the orifice of the nozzle  12  can receive adhesive from the aforementioned source. The arrangement is or can be such that the nozzle  12  can discharge adhesive only during travel of the carriage  8 , i.e., while the orifice of the nozzle  12  sweeps along the spine  1  of the stack  2  at the coating station  4 . 
     At such time, the activating means  33   a  positions the nozzle  13  in the retracted or inoperative position shown in FIG. 1 (i.e., the spring  32   a  is caused to store energy or to store additional energy). Furthermore, the nozzle  13  is then sealed from the source of adhesive. The two nozzles can receive adhesive from a common source. 
     The next step involves a movement of the carriage  8  relative to the coating station  4  (e.g., in a direction from the right to the left, as viewed in FIG.  1 ). The roller followers  36 ,  37  cooperate with the exposed surfaces  38  of the two clamping elements  6  at the station  4  to ensure that the nozzle  12  applies a film or coat or layer of adhesive paste in an optimum manner. The elasticity of the sidewalls  19  of the frame  14  for the nozzle  12  renders it possible to compensate for eventual inaccuracies, e.g., for departures of movement of the carriage  8  along the guide  7  from an ideal or optimum movement. Moreover, the elastic sidewalls  19  ensure that the roller followers  36 ,  37  remain in uninterrupted contact with the exposed surfaces  38  of the respective clamping elements  6  at the coating station  4 , even if the direction of movement of the carriage  8  along the guide  7  slightly departs from the longitudinal direction of the spine  1  at the station  4 . In other words, the feature that the sidewalls  19  are elastically deformable (or that at least one of these sidewalls is elastically deformable) compensates for at least some inaccuracies (including play, e.g., as a result of wear) of guidance of the carriage  8  and hence also of the frame  14  for the unit  9  during application of adhesive paste to the spine  1  of the stack  2  confronting the advancing nozzle  12 . This has been found to contribute to the quality of the adhesive applying operation. 
     Once the coating of the spine  1  at the station  4  by the nozzle  12  is completed, the units  9 ,  11  on the carriage  8  are again located outside of such station and the turret  3  can be indexed to advance the freshly treated stack  2  beyond the station  4  and to deliver a further (still uncoated) stack into the range of the nozzle  13 . The nozzle  12  is deactivated and pivoted to the inoperative position while the nozzle  13  is free to receive adhesive from the source. The carriage  8  is moved in a direction from the left to the right (as viewed in FIG.  1 ), and the nozzle  13  applies a coat of adhesive to the spine  1  at the station  4  while the roller followers on the frame for the nozzle  13  track the external surfaces  38  of the clamping elements  6  which are then located at the coating station. 
     An advantage of plural nozzles is that the improved apparatus can treat stacks  2  at a higher frequency because each and every movement of the carriage  8  along the coating station  4  entails the application of a film of adhesive to a freshly delivered stack. 
     It is also within the purview of the invention to provide the carriage  8  with a single adhesive applying unit ( 9  or  11 ) and to employ a single nozzle ( 12  or  13 ) which is arranged to apply adhesive to the spine of a different stack at the station  4  during each movement of the single nozzle along the coating station. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of the above outlined contribution to the art of applying adhesive to the spines of stacks of sheets and the like and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.