Patent Publication Number: US-2007096389-A1

Title: Device for adapting a stop to a sheet stack edge in a sheet processing machine, in particular a printing press

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2005 051 299.2, filed Oct. 26, 2005; the prior application is herewith incorporated by reference in its entirety.  
     BACKGROUND OF THE INVENTION  
     Field of the Invention  
      The invention relates to a device for setting a stop against a stack edge in a sheet processing machine, in particular a printing press.  
      During stack formation in the delivery of sheet processing machines, it is possible for the front and rear edge of the forming stack not to be parallel. The reason therefor can be cut tolerances during paper cutting from a roll or else different deformations of the sheet over its sheet width due to a different level of ink coverage. However, as a rule, the stops which are critical for the stack formation at the front and rear edge of the stack are parallel and also move only in parallel, so that compensation for non-parallel front and rear edges is not possible. As a result, stacks which do not quite have accurate edges can be produced, which then normally additionally have to run over a vibrating table for further processing.  
      European Patent EP 0 248 372 B1, corresponding to U.S. Pat. No. 4,813,661, has disclosed a device which, on the stop for the rear stack edge, has brushes with bristles pointing obliquely downward into the stacking region. The brushes are intended to press the falling sheets against the front edge stop.  
      European Patent EP 0 254 837 B1, corresponding to U.S. Pat. No. 4,828,246, discloses adjustable brushes on the rear edge stop, which move in a pivoting manner as the intermediate stacking device is controlled up and down.  
      In that case, the pivoting movement is carried out about an axis disposed transversely with respect to the sheet transport direction and disposed parallel to the front edge stops.  
     SUMMARY OF THE INVENTION  
      It is accordingly an object of the invention to provide a device for adapting a stop to a sheet stack edge, in particular a rear edge, running obliquely, in a sheet processing machine, in particular a printing press, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type.  
      With the foregoing and other objects in view there is provided, in accordance with the invention, a device for sheet stack formation in a sheet processing machine. The device comprises a stop mounted to be set against a stack edge obliquely relative to a sheet transport direction.  
      In accordance with another feature of the invention, a rear edge stop for a sheet stack in a delivery can also be set obliquely with respect to front edge stops, so that a stack that is not straight can be produced.  
      In accordance with a further feature of the invention, the device for adapting the sheet edge stop is disposed in such a way that its format can be adjusted, so that different format lengths can be processed. The format adjustment can be carried out by a motor and can therefore be driven with remote adjustment from a control computer of the sheet processing machine.  
      In accordance with a concomitant feature of the invention, it is additionally possible to use separate motors, which are each disposed on a respective side of the sheet stack and drive a common crossmember or axle for the stops. In this way, both the format adjustment and the oblique setting of the stops can be carried out automatically.  
      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 adapting a stop to a sheet stack edge in a sheet processing machine, in particular a printing press, 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, longitudinal-sectional view of a sheet processing rotary printing press;  
       FIG. 2  is an enlarged, fragmentary, side-elevation view of a rear edge stop with format and oblique adjustment;  
       FIG. 2A  is a top-plan view of the rear edge stop according to  FIG. 2 ;  
       FIG. 3  is a fragmentary, side-elevation view of a rear edge stop with motor format setting and manual oblique setting;  
       FIG. 3A  is a top-plan view of the rear edge stop according to  FIG. 3 ;  
       FIG. 4  is a fragmentary, side-elevation view of a rear edge stop with motor format adjustment and oblique adjustment; and  
       FIG. 4A  is a top-plan view of the rear edge stop according to  FIG. 4 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring now to the figures of the drawings in detail and first, particularly, to  FIG. 1  thereof, there is seen a machine for processing sheets  7 , for example a printing press  1 , which has a feeder  2 , at least one printing unit  3  and  4  and a delivery  6 . The sheets  7  are removed from a sheet stack  8  and, separated or overlapping, are fed to the printing units  3  and  4  over a feed table  9 . The printing units each contain a plate cylinder  11 ,  12 , in a known manner. The plate cylinders  11  and  12  each have devices  13 ,  14  for fixing flexible printing plates. Furthermore, each plate cylinder  11 ,  12  is assigned a device  16 ,  17  for semiautomatic or fully automatic printing plate change.  
      The sheet stack  8  lies on a stack board  10  which can be raised under control. The removal of the sheets  7  takes place from an upper side of the sheet stack  8  through the use of a suction head  18 , as is known. The suction head  18 , inter alia, has a number of lifting and dragging suckers  19 ,  21  for separating the sheets  7 . Furthermore, blowing devices  22  are provided to loosen the upper sheet layers, and sensing elements  23  for stack tracking. A number of side and rear stops  24  are provided in order to align the sheet stack  8 , in particular the upper sheets  7  of the sheet stack  8 .  
      Following sheet processing, the sheet  7  is deposited on a sheet stack  27  in the delivery  6  of the sheet processing machine through the use of a gripper system  26 , in particular through the use of a chain gripper system in the exemplary embodiment. At least one front edge stop  28  and at least one rear edge stop  29  ensure good stack formation.  
      According to  FIGS. 2 and 2 A, the rear edge stop  29  is formed as a crossmember and in each case is held in a holder  31 ,  32  at the side of the sheet stack  27 . The rear edge stop or crossmember  29  has a height which provides a stop surface for a plurality of rear sheet edges  30 . The holders  31 ,  32  are each fixed to a respective actuating device  33 ,  34  that can be moved linearly in and counter to the sheet transport direction. Each actuating device or format adjusting device is preferably a belt drive having an endlessly circulating belt  35 ,  40 , two deflection rollers  36 ,  38  and drive rollers  37 ,  39  for the belts  35 ,  40 . An actuating motor  41 ,  42 , which is provided for each drive roller  37 ,  39 , can be driven by a machine control system for setting purposes.  
      In the event of a rear edge running obliquely with respect to the front edge of a sheet, the rear edge stop  29  is accordingly set obliquely, by making movement travels of the holders  31  and  32  appropriately different. The result of an oblique setting of the crossmember  29  is a small length change as compared with a crossmember  29  disposed parallel to the front stops  28 . This is compensated for by a slot/pin coupling  46 , which is provided on one side of the crossmember  29 . Only a hole/pin coupling  47  is provided on the opposite side.  
      In the second exemplary embodiment according to  FIGS. 3 and 3 A, provision is made to interconnect the actuating devices  33 ,  34  through the use of a synchronization shaft  48 , so that only a single actuating motor  49  is needed for a format adjustment of the rear edge stop  29 .  
      The oblique adjustment can be set separately from the format setting of the rear edge stop  29 . For this purpose, the mounting of the crossmember  29  on the holder  32 , specifically the slot/pin coupling, is replaced by a stop/spring system  51 ,  52 ,  53 . In this case, a free end  50  of the crossmember  29  is supported on a horizontally oriented guide  51  and is pressed against a spring  53  through the use of an adjustable stop  52 . The stop  52  is disposed in such a way that it can be adjusted manually or remotely through the use of an actuating motor  54  under the control of the machine control system.  
      During an oblique adjustment of the crossmember  29 , the free end  50  of the crossmember  29  is pivoted about a pivot point A, which is formed by the hole/pin coupling  47 .  
      In a simple embodiment according to  FIGS. 4 and 4 A, provision is made to mount the crossmember  29  on both sides of the sheet stack  27  in such a way that it can be displaced in the sheet transport direction in each of the holders  31 ,  32  by applying a force for displacing the crossmember  29  in the holders  31 ,  32  with respective springs  56 ,  57 , which are supported on the holders  31 ,  32 . The holders  31 ,  32  are each disposed on the adjustable-format devices  33 ,  34 .