Patent Publication Number: US-7708277-B2

Title: Sheet delivery and sheet-processing printing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority, under 35 U.S.C. §119, of German patent application DE 10 2008 013 321.3, filed Mar. 10, 2008; the prior application is herewith incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a sheet delivery comprising an endless conveyor for conveying printed sheets, and also comprising a secondary gripper with a gripper bar by means of which the printed sheets are received at their trailing edges by the endless conveyor and are deposited on a delivery stack, and with a coupler transmission for generating an annular circulatory movement of the gripper bar. 
     Such sheet deliveries are described in commonly assigned German published patent application DE 103 43 428 A1 and its counterpart U.S. Pat. No. 7,261,291 B2, as well as in commonly assigned German published patent application DE 103 45 703 A1. Those respectively comprise an endless conveyor in the form of a chain conveyor, the endless chains of which are fitted with gripper bars for securing the leading edges of the printed sheets and gripper bars for simultaneously securing the trailing edges of the printed sheets. The secondary gripper performs a circulatory movement in the form of an elongate ring, in order to receive with its gripper bar the trailing edges of the printed sheets from the gripper bars of the endless conveyor and to deposit the printed sheets on the delivery stack. The annular circulatory movement of the gripper bar of the secondary gripper is driven by a coupler transmission, which in turn is driven by a cam mechanism. Cam rollers which run on control cams of the cam mechanism are fitted on oscillating cranks of the coupler transmission. The above-mentioned DE 103 43 428 A1 and U.S. Pat. No. 7,261,291 B2 point out that, for realizing the secondary-gripper transmission, precautions have to be taken to prevent the cam-controlled elements of the transmission, that is to say the cam rollers, from lifting off from the control cams. Such lifting off is a particular risk at high machine speeds. However, the precautions mentioned are not precisely specified in the cited prior art. 
     It has been found that the geometry of the prior-art coupler transmission is unfavorable in respect of precautions which could prevent the cam rollers from lifting off from the control cams. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a sheet delivery, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a secondary gripper system that functions reliably even at high machine speeds. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a sheet delivery, comprising: 
     an endless conveyor for conveying printed sheets; 
     a secondary gripper with a gripper bar configured to receive the printed sheets from the endless conveyor at trailing edges thereof and to deposit the printed sheets on a delivery stack; and 
     a coupler transmission for generating an annular circulatory movement of the gripper bar, the coupler transmission including crisscrossing oscillating cranks. 
     In other words, the objects of the invention are achieved by a sheet delivery with an endless conveyor for conveying printed sheets, and also comprising a secondary conveyor with a gripper bar by means of which the printed sheets are received at their trailing edge by the endless conveyor and are deposited on a delivery stack, and with a coupler transmission for generating an annular circulatory movement of the gripper bar, is wherein the coupler transmission has crisscrossing oscillating cranks. 
     The geometry according to the invention of the coupler transmission is advantageous in respect of the configuration of a secondary-gripper cam mechanism which drives the coupler transmission. As a result, the cam-controlled elements of the transmission can be spring-mounted in a particularly straightforward manner such that lifting off of these elements of the transmission from control cams can be avoided even at high machine speeds. Great precision of the circulatory movement of the gripper bar of the secondary gripper and high functional reliability are achieved by the geometry of the coupler transmission, which is advantageous in respect of spring-mounting the cam mechanism. 
     In accordance with an added feature of the invention, the oscillating cranks are respectively mounted pivotably at an articulation and the oscillating cranks cross one another in a region located horizontally between the two articulations. Accordingly, as seen in the horizontal viewing direction, one of the two articulations is located on one side of the crossover point of the two oscillating cranks and the other of the two articulations is located on the other side of this crossover point. This creates favorable preconditions in order for the cam mechanism which drives the coupler transmission to be arranged above the two articulations of the coupler transmission, which is advantageous in respect of straightforward assembly. 
     In accordance with another feature of the invention, the oscillating cranks respectively have a first lever arm and a second lever arm, the first lever arms carrying cam rollers and the second lever arms crossing one another. In this case, the first lever arms do not cross one another. 
     In accordance with a concomitant feature of the invention, the oscillating cranks are two driving oscillating cranks, a driven oscillating crank being articulated on one of the two driving oscillating cranks and a coupler being articulated on the other of the two driving oscillating cranks, which coupler is articulated on said driven oscillating crank. It is possible here for the driven oscillating crank to be articulated at its one end on the one driving oscillating crank and to be connected at its other end to the gripper bar of the secondary gripper, for example via an articulation joint. 
     With the above and other objects in view there is also provided, in accordance with the invention, a printing machine which is equipped with the sheet delivery according to the invention as summarized above. The printing machine according to the invention is preferably an offset rotary printing machine. 
     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 sheet delivery means, 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 SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a schematic view of a chain conveyor and a secondary gripper; 
         FIG. 2  is a three-dimensional illustration of a cam mechanism for driving the secondary gripper; 
         FIG. 3A  shows the cam mechanism in an illustration corresponding to the viewing direction Ilia in  FIG. 1 ; 
         FIG. 3B  shows a sectional view of a section taken along the line IIIb-IIIb in  FIG. 3A ; 
         FIG. 4  is a perspective view of balance weights which form constituent parts of an overall transmission of the secondary gripper; 
         FIG. 5A  is a plan view of a gripper bar of the secondary gripper; 
         FIG. 5B  shows an illustration corresponding to the viewing direction Vb in  FIG. 5A ; and 
         FIG. 5C  shows an illustration corresponding to the viewing direction Vc in  FIG. 5A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a detail of a printing machine  1 . The printing machine  1  is an offset rotary printing machine. The detail shows a sheet delivery  2  of the printing machine  1 . The sheet delivery  2  comprises an endless conveyor  3 , which is a chain conveyor. The endless conveyor  3  comprises, on the drive side and the operating side in each case, an endless chain for carrying gripper bars  4  for retaining the leading edges of the printed sheets  5  and an endless chain for carrying gripper bars  6  for retaining the trailing edges of the printed sheets  5 . The drawing illustrates a forward strand  7  of that endless chain on one machine side which carries the leading-sheet-edge gripper bars and a return strand  8  of that endless chain on the same machine side which carries the trailing-sheet-edge gripper bars. The forward strands of all four endless chains run horizontally in the direction towards a delivery stack  9 , on which the printed sheets  5  are deposited. The four return strands  8  of the endless chains run parallel to the forward strands  7 , but in the direction away from the delivery stack  9 . The arrows in the drawing indicate symbolically the running directions of the forward strands  7  and of the return strands  8 , which are arranged above the forward strands  7 . 
     A secondary gripper  10  receives the trailing edges of the printed sheets  5  from those gripper bars  6  of the endless conveyor  3  which secure these trailing sheet edges as these gripper bars  6  pass through the region of the forward strands  7 . The secondary gripper  10  comprises a gripper bar  11  which, like the gripper bars  4  and  6  of the endless conveyor  3 , is equipped with a series of grippers by means of which the respective printed sheet  5  is clamped in. For the purposes of gripping the printed sheet  5  and of depositing the printed sheet  5  on the delivery stack  9 , the gripper bar  11  of the secondary gripper  10  executes an annular circulatory movement  12 , which is indicated by dash-dotted ghost lines in the drawing. 
     A transmission  13  is provided in order to generate this circulatory movement  12 . The transmission comprises, as a partial transmission on the drive side and on the operating side, a respective cam mechanism and a coupler transmission  14  which is driven by the respective cam mechanism. The cam mechanism located on the one machine side comprises a first control-cam pair  15  and the cam mechanism located on the other machine side comprises a second control-cam pair  16 , as can be seen in  FIG. 2 .  FIG. 1  shows just one of the two control-cam pairs  15 ,  16  and one of the two coupler transmissions  14 . Each control-cam pair  15 ,  16  comprises a first cam  17 , which is located on the inside as seen in the axial direction, and a second, axially outer cam  18 . The two first cams  17  and the two second cams  18  are each radial cams, and all four cams  17 , 18  have a common geometrical axis of rotation  19  (cf.  FIG. 3A ). 
     Since the two coupler transmissions  14  are constructed identically to one another, the following description of the one coupler transmission  14  also applies analogously to the other. The coupler transmission  14  shown comprises a first driving oscillating crank  20  with a first lever arm  20 . 1  and a second lever arm  20 . 2 , and also comprises a second driving oscillating crank  21  with a first lever arm  21 . 1  and a second lever arm  21 . 2 . The two driving oscillating cranks  20 ,  21  are mounted on an auxiliary framework  24 , a so-called transmission casing, such that they can be rotated via articulations or articulation joints  22 ,  23 . The second lever arm  21 . 2  of the second driving oscillating crank  21  is connected, via a further rotary articulation, to an output oscillating crank  25  which, by way of its end opposite to the further rotary articulation, carries the gripper bar  11  of the secondary gripper  10 . The second lever arm  20 . 2  of the first driving oscillating crank  20  is connected, via a rotary articulation, to a coupler  26 , which is connected to the output oscillating crank  25  via a further rotary articulation. Accordingly, the second driving oscillating crank  21  and the output oscillating crank  25  together form a first double link and the first driving oscillating crank  20  and the coupler  26  together form a second double link. The latter is articulated on the first double link. The first lever arm  20 . 1  of the first driving oscillating crank  20  carries a first cam roller  27 , which runs over the first cam  17 . The first lever arm  21 . 1  of the second driving oscillating crank  21  carries a second cam roller  28 , which runs over the second cam  18 . 
     The articulation  22 , about which the first driving oscillating crank  20  can be pivoted, and the articulation  23 , about which the second driving oscillating crank  21  can be pivoted, are located above all of the forward strands  7  of the endless conveyor  3 . The forwards strands  7  are located substantially on one and the same vertical height level. The two articulations  23  are located beneath all of the return strands  8 . The return strands  8  are located substantially on one and the same vertical height level. The second lever arm  20 . 2  of the first driving oscillating crank  20  and the second lever arm  21 . 2  of the second driving oscillating crank  21  together form a crossover point  29 , as seen in the horizontal direction perpendicular to the plane of  FIG. 1 . This crossover point  29 , like the articulations  22 ,  23 , is located in a region which, as seen vertically, is situated between the forward strand  7  on the one hand, and the return strand  8 , on the other hand. As seen in the horizontal direction parallel to the plane in  FIG. 1 , the crossover point  29  is located between the articulation  22  of the first driving oscillating crank  20  and the articulation  22  of the second driving oscillating crank  21 . 
     Of the two lever arms which have the first oscillating cranks and the second driving oscillating cranks on the operating side and the drive side in each case,  FIG. 2  illustrates in each case only the first lever arm  20 . 1  and  21 . 1 , respectively. By means of a first torsion spring  30 , the two first driving oscillating cranks  20 , namely the one and the drive side and that on the operating side, are braced in rotation in relation to one another, in which case the force of the first portion spring  30  presses the first cam rollers  27  against the first cams  17 . By means of a second torsion spring  31 , the two second driving oscillating cranks  21  are braced in rotation in relation to one another, in which case the second cam roller  28  of the second driving oscillating crank  21  which is arranged on the drive side is forced by the second torsion spring  31  against the circumferential surface of the second cam  18  which is arranged on the drive side, and the second cam roller  28  of the second driving oscillating crank  21  which is arranged on the operating side is forced by the second torsion spring  31  against the circumferential contour of the second cam  18  which is arranged on the operating side. The first torsion spring  30  is arranged coaxially with the articulations  22  and the second torsion spring  31  is arranged coaxially with the articulations  23 . The first cams  17  are connected in a rotationally fixed manner to the two second cams  18 . The first cams  17  are contoured, and the articulations  22  are placed, such that those cam mechanisms on the drive side and the operating side which comprise the first cams  17  realize the same laws of motion. Similarly, the paths of the second cams  18  are configured, and the articulations  23  are arranged, such that the cam mechanism which is located on the drive side of the printing machine  1  and comprises the one second cam  18  realizes the same law of motion as the cam mechanism which is located on the operating side and comprises the other second cam  18 . 
     The first cam rollers  27  butt against points on the circumference of the first cams  17 , these points on the circumference being selected such that the two first driving oscillating cranks  20  execute pivoting movements in the same direction. For example, the two first driving oscillating cranks  20 , in the first instance, move together in the clockwise direction and, once they have gone beyond the dead-center position or turning points of their pivoting movements, they move together in the counterclockwise direction. It is also the case that the angle-at-circumference points at which the second cam rollers  28  butt against the second cams  18  are selected such that the second driving oscillating cranks  21  together execute pivoting movements in the same direction when the second driving oscillating cranks  21  are driven by the rotating second cams  18 . The first cam rollers  27  here butt against flanks of the first cams  17  which are directed away from one another, in which case, when the first driving oscillating cranks  20  move in the clockwise direction, the flank of the one first cam  17  presses onto the first cam roller  27  which butts against this cam flank and, when the first driving oscillating cranks  20  move in the counterclockwise direction, the flank of the other first cam  17  presses onto the first cam roller  27  which butts against that cam flank. Analogously, the second cam rollers  28  butt against flanks of the second cams  18  which are directed away from one another, in which case, when the second driving oscillating cranks  21  move in the clockwise direction, the flank of the one second cam  18  presses onto the second cam roller  28  which butts against the same and, when the second driven oscillating cranks  21  move in the counterclockwise direction, the flank of the other second cam  18  presses onto the second cam roller  28  which butts against the same. The arrangement explained above is advantageous in respect of minimizing the loading and thus the wear to the first and second cam rollers  27 ,  28 . 
       FIG. 3A  shows that the first and second cams  17 ,  18  are fitted in a rotationally fixed manner on a hollow shaft  32 . The hollow shaft  32  is driven in rotation by an electric motor via a chain wheel which is seated on the shaft, that is not illustrated in the drawing. The motor drives a drive chain, which is not illustrated in the drawing either and in which the chain wheel engages. The motor may be the main drive of the printing machine  1 . The hollow shaft  32  is a so-called synchronizing shaft by means of which that part of the transmission  13  which is arranged on the drive side and the partial transmission which is arranged on the operating side are connected and synchronized. 
     It is advantageous in production terms to have the hollow shaft  32  arranged above the return strands  8  of the endless conveyor  3 . This makes it possible, first of all, to assemble the endless conveyor  3  including its endless chains and, at the same time, to preassemble, as a further structural unit, the secondary gripper  10  including its transmission  13  and, thereafter, to fit the secondary gripper  10  on the endless conveyor  3 . This positioning of the one structural unit on the other is similar to the so-called “marriage” in automotive engineering where the preassembled bodywork is positioned on the drive and chassis unit. 
     Within the hollow shaft  32 , a spring in the form of a torsion spring  33  extends from the drive side to the operating side. A balance weight  34  for torque-compensating purposes is fitted in a rotationally fixed manner in each case at the two ends of this torsion spring  33 . The two balance weights  34  are braced for rotation in relation to one another by the torsion spring  33 . The hollow shaft  32  has, at each end, two diametrically arranged slots  35  which open out in the end periphery of the hollow shaft  32 . As can best be seen in the sectional illustration in  FIG. 3B , these slots  35  have radial carrying arms  36  of the respective balance weight  34  engaging through them, and provided between the respective carrying arm  36  and slot  35  in the circumferential direction is an amount of play  37  sufficient to allow the balance weight  34  to move back and forth in the circumferential direction relative to the hollow shaft  32 . The balance weights  34  are disks that are arranged coaxially with the first cams  17 , the second cams  18  and third cams  38 . 
     In contrast to the first and second cams  17 ,  18 , which are disposed such that they can be rotated relative to the exterior frameworks  24 , the one third cam  38  is connected in a rotationally fixed manner to the auxiliary framework  24  and the drive side and the other third cam  38  is connected in a rotationally fixed manner to the auxiliary framework  24  on the operating side. The third cams  38  are likewise radial cams. 
     The balance weights  34  are arranged between an inner side wall of the respective auxiliary framework  24  and the respective control-cam pairs  15 ,  16 . Each balance weight  34  is arranged between the respective third cam  38  and the respective first and second cams  17 ,  18 , the third cams  38  being placed on those sides of the balance weights  34  which are located closer to the machine interior. 
     To give a better overview,  FIG. 4  does not illustrate the first cam  17  and second cam  18 , which are actually present on the side of the machine which forms the front. Each balance weight  34  is driven in rotation via a double link  39 . The two double links  39  are arranged diametrically in relation to one another. 
     On account of the two double links  39  being of identical construction, the following description of the one double link also apply analogous to the other. The double link  39  comprises a coupler  40 , which is fitted on the first cam via a first rotary articulation  41 . The coupler  41  has its end which is opposite to the first rotary articulation  41  connected to an operating crank  43  via a second rotary articulation  42 . At its end which is opposite to the second rotary articulation  42 , the oscillating crank  43  carries a cam roller  44 , which runs over the third cam  38 . Between the cam roller  44  and the secondary rotary articulation  42 , the oscillating crank  43  is connected to the balance weight  44  via a third rotary articulation  45 . During operation, the torque is transmitted from the first cams  17 , via the first rotary articulations  41 , to the double links  39  and from these, via the second rotary articulations  42 , to the balance weights. The cam rollers  44  here run over the third cams  38 , which do not rotate and thus cause the oscillating crank  43  to pivot about the third rotary articulations  45 . This pivoting movement causes the respective double link  39  to straighten out, in which case it transmits a circumferentially directed force component, via the third rotary articulation  45 , to the respective balance weight  34 . The torque generated by this force component coincides with the torque which is transmitted from the hollow shaft  32 , via the first cam  17  and the first rotary articulation  41 , to the balance weight  34 . 
     The contour of the third cams  38  is designed such that the double link  39 , as it circulates about the respective third cam  38 , alternately straightens out and is folded closer together again. Accordingly, there is a change in the algebraic sign of said torque, which is generated by the third cam  38  and coincides with the torque which is transmitted from the hollow shaft  32  to the balance weight  34 . In other words, as a result of the cam-generated pivoting movement of the double links  39 , the balance weights  34  are periodically circumferentially pushed in the direction of the first rotary articulations  41  and pulled away from the same. 
     This compensates for torque fluctuations which are caused by the mass inertia of the transmission  13  and of the gripper bar  11  during acceleration and deceleration of the same. These torque fluctuations are also referred to as dynamic interference torques and are dependent on speed. 
     The balance weights  34  serve for compensating for torque fluctuations which are caused by the weight of the gripper bar  11  as it circulates along the circulatory path  12 —cf. FIG.  1 —in other words the so-called static interference torques. These static interference torques do not depend on speed. As the gripper bar  11  circulates along the circulatory path  12 , the gripper bar  11  is first of all raised by the transmission  13  counter to the action of the weight of the gripper bar  11  and is then lowered again, by the transmission  13 , under the weight of the gripper bar. The displacement which is necessary here gives rise to the static interference torques, although these are compensated for by the countermeasures explained above. Via the balance weight  34 , the torsion spring  33  braces the double links  39 , which are articulated on the balance weights, for rotation in relation to one another such that the spring force of the torsion spring  33  presses the cam rollers  44  against the third cams  38 . 
       FIGS. 5A to 5C  show the gripper bar  11  of the secondary gripper  10  in detail. The gripper bar  11  comprises a series of grippers  46  which each have a gripping finger  47  and a gripper support  48 . The printed sheet  5  is clamped in between the respective gripping finger  47  and the associated gripper support  48 . The gripping fingers  47  are seated on a gripper shaft  49 , the rotation of which causes the gripping fingers  47  to pivot relative to the gripper supports  48 . An intermediate shaft  50  is arranged parallel to the gripper shaft  49  and is connected thereto via a transmission  51 . The transmission  51  is a coupler transmission, specifically a four-bar mechanism, and comprises a first oscillating crank  52 , which is connected in a rotationally fixed manner to the intermediate shaft  50 , a second oscillating crank  53 , which is connected in a rotationally fixed manner to the gripper shaft  49 , and a coupler  54 , which is articulated on the two oscillating cranks  52 ,  53 . 
     A rail-like chain guide  56 , for guiding the endless chains of the endless conveyors  3 , is fitted on the inside of a side wall  55  of the sheet delivery  2 . The chain guide  56  has two grooves  57 , in which run rollers which are fitted on the endless chains, but are not illustrated in the drawing. The two endless chains which are arranged on the one side of the machine are guided by the chain guides  56  in the region of the forward strands  7  of these chains. A further chain guide is arranged on the other side of the machine and guides the other two endless chains in the region of their forward strands. 
       FIG. 5C  shows that the gripper bar  11  is angled, in order to engage in a sustantially U-shaped manner around the chain guide  56  and the bottom periphery of the side wall  55 . The gripper shaft  49  is located above the bottom periphery of the chain guide  56 , and the intermediate shaft  50  extends beneath the chain guide  56  and the side wall  55 , past the same, as far as a cam mechanism  58  which is arranged outside the machine framework. 
     The cam mechanism  58  is located on that side of the chain guide  56  which is directed away from the machine interior, and it comprises a control cam  59 , which is fitted in a stationary manner on the machine framework, and a cam roller  60  on a roller lever  61 . The roller lever  61  is connected in a rotationally fixed manner to the intermediate shaft  50  and moves the intermediate shaft  50 . As the gripper bar  11 , together with the roller lever  61 , runs past the control cam  59 , the cam roller  60  comes into contact with the control cam  59 , in which case the gripping fingers  47  are actuated via the intermediate shaft  50 , the transmission  51  and the gripper shaft  49 . In  FIG. 5   b , an arrow indicates symbolically the force  62  to which the roller lever  61  is subjected by the control cam  59 . 
     The control cam  59  is a so-called gripper-closing cam which pivots the gripping fingers  47  in the direction of the gripper supports  48  counter to the force of a non-illustrated restoring spring in order to close the grippers  46  and to clamp the printed sheet  5  between the elements  47  and  48 . The grippers  46  are opened by the force of the restoring spring in a position of the gripper bar  11  relative to the control cam  59  in which the control cam  59  allows the restoring spring, which is arranged on the gripper bar  11 , to be relieved of stress.