Abstract:
A device for backing rounded book blocks ( 2 ) clamped near the spine, by a pressing beam ( 9 ) and a slide ( 7 ) that accommodates the pressing beam ( 9 ) and can be alternately displaced along arc-shaped races ( 6 ) in a swinging fashion by driving means ( 17 ) in a height-adjustable supporting bearing ( 5 ) that is laterally supported against the effect of a spring element ( 29 ). Members are provided for controlling ( 21, 22, 32, 33 ) the lateral position of the supporting bearing ( 5 ) and for lowering and raising ( 10, 11, 12 ) the pressing beam into the starting position for its return stroke. An eccentric starting position is realized during the lowering of the pressing beam ( 9 ) on the spine ( 2   a ), in the form of a swinging position of the slide ( 7 ) that is offset toward the opposite side of the spine center ( 2   b ) referred to the respective side to be backed thereafter.

Description:
BACKGROUND  
       [0001]    The present invention pertains to a device for backing book blocks. 
         [0002]    EP 0 676 303 B1 shows a device for backing book blocks (FIGS. 11 and 12), in which the supporting bearing is laterally supported against the effect of disc spring assemblies in the form of a spring element such that a pressing force for turning over the sheets of the book block is applied in the lateral regions of the spine. During the return stroke of the pressing beam toward the center of the block spine, the effect of the disc spring assembly is neutralized in order to prevent the outer sheets that are laterally turned over from being carried along. In this case, the motion of the pressing beam may be additionally controlled such that it clears the block spine during its return stroke due to an upward motion and is subsequently placed back on the spine in the block center in order to back the opposite side of the block spine. 
         [0003]    The control of the disc spring assemblies and therefore the lateral position of the supporting bearing is realized with rams that are arranged laterally of the supporting bearing and controlled by cam wheels, wherein these rams act upon the supporting bearing in alternating directions and transfer the disc spring assemblies from a supporting position for applying a pressing force into a relieving position. 
         [0004]    The above-described position control, in which the spring force is relieved, makes it possible to back sheets with high as well as low rigidity without causing the sheets to buckle or to be pushed back again. In this case, it suffices to back each side of the block spine once in order to achieve the desired mushroom-like spine shape. 
         [0005]    When the pressing beam is centrally placed on the block spine, it may occur, however, that the pressing beam causes the central sheets to buckle such that creases are formed. A loose contact between the pressing beam and the center of the block spine, in contrast, reduces the smoothing of the elongations in the glue film caused by the rounding, whereby the previously created rounding in the center of the block spine is stabilized. 
       SUMMARY  
       [0006]    The present invention is based on the objective of developing a device for backing book blocks of the general kind described above, that makes it possible to improve the quality of the book blocks. 
         [0007]    According to the present disclosure, this objective is attained in that the pressing beam is arranged in an eccentric starting position when the pressing beam is lowered on the book block. The slide accommodating the pressing beam is displaced away from the spine center into a swinging position that lies on the opposite side referred to the respective side to be backed thereafter. Consequently, the block spine center is also swept with each backing of one side without causing the pressing beam to act upon the outer trailing sheets of the book block referred to the pressing motion which were backed during the opposite motion of the pressing beam or are yet to be backed. An exact height adjustment is not required because the block spine center is swept during two oppositely directed rolling/drawing motions without buckling the sheets in the block center by a pressing beam that is moved toward the block center from above. 
         [0008]    According to an additional development, the supporting bearing is laterally displaced away from the block center toward the same side in the eccentric starting position such that the pressing beam is initially placed on the block spine with its center of swinging motion that approximately lies in the effective area and the ensuing rolling/drawing motion of the pressing beam takes place while it is in constant contact with the block spine, namely without causing undesirable shifting of the sheets. 
         [0009]    Advantageous additional developments will become evident from the detailed description below. 
     
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0010]    Characteristics of the invention are described in greater detail below with reference to one preferred embodiment that is illustrated in the accompanying drawing. In these drawings, 
           [0011]      FIG. 1  shows a partially schematic representation of a backing station with the pressing beam positioned in the starting position for its lowering motion; 
           [0012]      FIG. 2  shows an identical representation of the backing station with the lowered pressing beam carrying out the backing motion; 
           [0013]      FIG. 3  shows the backing station while the pressing beam is raised at the end of a backing motion; 
           [0014]      FIG. 4  shows the backing station with the pressing beam positioned in a second starting position, and 
           [0015]      FIG. 5  shows a detailed illustration of the spring force adjustment. 
       
    
    
     DETAILED DESCRIPTION  
       [0016]    With reference to the backing station as shown in the Figures, it should be understood that after a spine rounding process, the book blocks  2  are transported into a backing station  1  by means of a reciprocating transport clamp carriage  3 , wherein the book blocks  2  with their rounded spines  2   a  are provided with a mushroom-like spine shape that is defined by a deep or flat joint  2   c.    
         [0017]    The backing process is carried out with a forming tool realized in the form of a pressing beam  9  that moves back and forward over the entire spine width of the book blocks  2  and has a concave effective area  9   a , whereby the sheets of the book block  2  are turned over toward both sides from the center  2   b  of the block spine  2  under the influence of pressure and friction, namely at an angle that increases outward. In order to carry out the backing process, the book block  2  is clamped between backing jaws  4  with a defined projection from the end of the rounding. 
         [0018]    The pressing beam  9  is exchangeably fixed on a receptacle  8  that is situated in a bridge-like slide  7  provided with arc-shaped grooves  7 a on both sides. The grooves guide the slide  7  in a swinging fashion in assigned roller races  6  of a supporting bearing  5  such that the center of swinging motion  18  approximately lies in the effective area  9   a . The pressing beam  9  is conventionally moved back and forward by the main drive with the aid of a driving rod  17  that engages on the slide  7  in an articulated fashion. 
         [0019]    The aforementioned supporting bearing  5  is suspended in a swinging fashion on a height-adjustable connecting rod  10 , wherein the common center of motion is centrally guided over the block spine  2  a by a coupling rod  16  that is rigidly connected to the machine frame while the supporting bearing  5  is supported with respect to a swinging motion about the aforementioned center of motion by a laterally connected cushioning coupling rod  22 . 
         [0020]    In order to realize the cyclic lowering and raising of the pressing beam  9  on and from the block spine  2   a , the connecting rod  10  is vertically displaced by a camshaft  11  that is controlled by a driving rod  12 . The height adjustment of the pressing beam  9  to the respective book block height is achieved by supporting the camshaft  11  in lateral plates  13  that can be vertically fixed by an adjusting device  15  while being guided in guides  14  of the machine frame. 
         [0021]    The pressing beam  9  is eccentrically lowered on the block spine  2   a  from above in a swinging position that is offset relative to the block center  2   b . The slide  7  with the pressing beam  9  accommodated therein is subjected to a lateral swinging motion of defined angle, for example, 15°. Its center of swinging motion  18  is additionally displaced away from the block center  2   b  by the offset  19  between the center lines due to the lateral displacement of the supporting bearing  5 , such that the displaced pressing beam  9  is initially placed on the block spine  2   a  with the center of swinging motion  18 . No undesirable shifting of the sheets occurs during this process and the pressing beam  9  does not act in the lateral area of this block spine side. 
         [0022]    A positioning control  21  is provided for laterally displacing the supporting bearing  5 . The positioning control varies the coupling point of the cushioning coupling rod  22 . The coupling point is arranged on a lever  32  that is supported in the frame in a pivoted fashion by a driving rod  33  of conventional driving means that are not illustrated in greater detail. In  FIGS. 1 to 4 , the respective position is displayed on a scale by means of a dial arranged on the lever  32 . Starting from a center position  32   a , first and second offset positions  32   b ,  32   c  are assumed depending on the side of the block spine  2   a , on which the pressing beam  9  is placed. 
         [0023]    After the pressing beam  9  is placed on the block spine, its swinging motion for backing the opposite side of the block spine  2   a  is initiated by the driving rod  17 , wherein the supporting bearing  5  is returned into the cushioned center position  32   a  during the swinging motion up to the block center  2   b . During the continued swinging motion of the pressing beam  9 , the supporting bearing  5  laterally yields to the cushioning coupling rod  22  against the spring force such that the pressing beam  9  carries out a rolling/drawing motion and a pressing force is applied to the lateral regions of the block spine  2   a  in order to turn over the sheets of the book block  2 . 
         [0024]    The cushioning coupling rod  22  is realized in the form of a rod  23  that is displaceably guided in bushings  26 ,  30   a  and b of a receptacle  25 . An articulated end  24  of the rod  23  serves for connecting the coupling rod  22  to the supporting bearing  5 , wherein a second articulated end  27  is situated in the receptacle  25  in order to connect the coupling rod  22  to the lever  32 . 
         [0025]    The bushing  26  of the aforementioned bushings  26 ,  30   a  and  b  is displaceably accommodated in the receptacle  25  while the bushings  30   a  and  b  are arranged in a holder  30  that is displaceably guided on tie rods  28  extending away from the receptacle  25 . A pressure spring  29  is situated between the bushings  26  and  30   b  that are respectively provided with a stop, wherein the pressure spring presses apart the aforementioned arrangement against a shoulder  23   a  and nuts  23   b  arranged on the rod  23  in order to realize a defined length of the coupling rod  22  in the unstressed state. 
         [0026]    When a compressive force acts upon the coupling rod  22  from outside in accordance with the backing process shown in  FIG. 2 , the rod  23  presses against the compression spring  29  via the nut  23   b , the holder  30  and the bushings  30   a  and  b  such that the coupling rod  22  is shortened due to the displacement of the holder  30  on the tie rods  28  and exerts a force of reaction in the form of a compressive force upon the supporting bearing  5 . 
         [0027]    At the end of the first backing process, the lever  32  is displaced into a relieving position  32   d  such that the pressure spring  29  is relieved. According to  FIG. 3 , the relieving stroke is so long that the coupling rod  22  reassumes its unstressed length and the pressing beam  9  is quasi drawn away from the block spine  2   a.    
         [0028]    The pressing beam  9  is raised by means of the driving rod  12 , the camshaft  11 , the connecting rod  1   0  and the supporting bearing  5  and caused to swing back into a second starting position for backing the opposite side of the, block spine  2   a  by the driving rod  17  and the slide  7 a as shown in  FIG. 4 . During this process, the position control  21  displaces the supporting bearing  5  into a correspondingly offset position that is defined by the displacement  32   c  of the lever  32 . 
         [0029]    During the backing of the second side of the block spine  2   a , a tractive force becomes effective on the coupling rod  22  after the coupling rod  22  is returned into its center position  32   a . This tractive force causes the bushing  26  to be displaced in the receptacle  25  against the spring force of the compression spring  29 . The supporting bearing  5  yields toward the respective backing side with a controlled force due to the elongation of the coupling rod  22  such that the desired rolling/drawing motion takes place again and a pressing force acts upon the block spine  2   a.    
         [0030]    At the end of the second backing process, the lever  32  is displaced into a relieving position for relieving the compression spring  29 . The pressing beam  9  is raised and moved back into its first starting position. During this process, the completely backed book block  2  is transported to an additional processing device by the transport clamp carriage  3  while a new rounded book block  2  is simultaneously supplied. 
         [0031]    A spring force adjustment  31  is provided in order to adapt the backing force to the respective composition of the sheets. According to  FIG. 5 , this is achieved by varying the distance between the two supporting points for the pressure spring  29  by means of the bushing  30   b  screwed into the holder  30 .