Patent Publication Number: US-6902520-B2

Title: Folding machine having at least one pair of knife shafts

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a folding machine having at least one pair of knife shafts, the knife shafts of which are, in a working position, mounted parallel to each other between two spaced-apart side walls of the folding machine. 
   2. Description of the Background Art 
   In order to be able to cut, cut out, perforate, crimp etc. folded paper sheets perpendicular to a fold, i.e. in the running direction of the sheets, pairs of knife shafts are provided upstream and downstream of the folding rollers of a folding unit. These generally concern pairs of knife shafts in which one knife shaft is fitted with upper knife tools and the other knife shaft is fitted with lower knife tools, said tools being arranged on a tool holder fitted on the knife shaft. The knife shafts are fitted with appropriate tools depending on the requirements of the task. A corresponding folding machine is disclosed, for example, in DE 30 25 239 C2. In the case of the known folding machines, the knife shafts are usually mounted on the side walls of the folding machine. For this reason, they can be removed only if the folding machine is at a standstill. For this purpose, it is generally necessary first of all to pull out the buckle plates. After their fastening has been released, the knife shafts then have to be lifted out over the side walls of the machine. Since the knife shafts are generally very heavy, this work is very laborious. Finally, the knife shafts can only be set in a precise manner when they are installed in the folding machine. For this purpose, auxiliary means are fitted in the direct vicinity of the knife shafts. These are, for example, rulers having a tape measure printed on them enabling the position of the tool to be read. 
   SUMMARY OF THE INVENTION 
   The invention is based on the object of providing, with structurally simple means, a folding machine in which rapid changing of the knife shafts is possible in a simple manner. 
   This object is achieved by a folding machine comprising at least one pair of knife shafts which are, in a working position, mounted parallel to each other between two spaced-apart side walls of said folding machine, wherein said knife shafts are mounted in a cassette which is displaceable through a sidewall facing an operator from an inserted position, in which said knife shafts are in an working position thereof, into a pull-out position, in which said knife shafts are located outside said folding machine. 
   Since the knife shafts are mounted in the cassette which can be displaced through the sidewall from the inserted position into the pull-out position, changing of the knife shafts is possible without removal of the buckle plates of a folding unit connected upstream. In addition, it is possible to preset a pair of knife shafts while the folding machine is running, as a result of which the set-up time can be substantially reduced. 
   The cassette is preferably arranged in a drawer which can be inserted and pulled out through the side wall. When the drawer is pulled out, the cassette can be removed and a new cassette placed into the drawer. After the drawer has been inserted, the changing of the pair of knife shafts is complete. 
   In one particular embodiment, the cassette has an end wall facing the drive and an end wall facing the operator, said walls being spaced apart and being connected to each other by a crosspiece. The knife shafts are mounted on the end by bearing devices. 
   The bearing devices of at least one knife shaft can preferably be adjusted in order to set the nip between the knife shafts. This adjusting device is part of the knife shaft cassette. The adjustment may take place outside the folding machine. 
   For a rapid connection to the drive facing the folding machine, the bearing devices facing the drive can be mounted rotatably in the end wall facing the drive, and pass through said end wall. 
   In order to center the cassette, it is advantageous if a respective fixing pin is fitted on the two end walls and, in the inserted position, engages in a centering opening in the respective side wall of the folding machine. 
   A precise setting of knife holders on the knife shafts can be achieved by the fact that a scale is provided on the knife shaft, said scale preferably being engraved in it. 
   Since the setting of the knife holders on the knife shafts can take place outside the machine, the operator can stand directly in front of the knife shaft cassette during the tool change, so that parallax errors do not occur. 

   
     BRIEF DESCRIPTION OF THE INVENTION 
     An exemplary embodiment of the invention will be explained in greater detail below with reference to drawings, in which: 
       FIG. 1  shows a folding machine with a pulled-out cassette, 
       FIG. 2  shows the folding machine of  FIG. 1  with an inserted cassette, 
       FIG. 3  shows a cassette in which a pair of knife shafts is fitted, 
       FIG. 4  shows the section IV—IV of  FIG. 3 , 
       FIG. 5  shows a perspective view of the cassette, 
       FIG. 6  shows a knife shaft on which a scale is provided, 
       FIG. 7  shows the scale of the knife shaft in  FIG. 6  on an enlarged scale, 
       FIG. 8  shows the view of  FIG. 4  on an enlarged scale, 
       FIG. 9  shows a left side view of the cassette of  FIG. 3  on an enlarged scale. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The folding machine  10  shown in  FIGS. 1 and 2  has a buckle-plate folding unit having a buckle plate  12 , downstream of which, in the running direction of the sheets, are arranged folding rollers  14 ,  16  which are mounted in a sidewall  18  facing the drive and a sidewall  20  facing the operator. As can be seen in  FIG. 2 , a pair of knife shafts comprising an upper knife shaft  22  and a lower knife shaft  24  is arranged downstream of the folding rollers  14 ,  16  in the running direction of the sheets. Five knife holders  26  are arranged at equal spacing, as seen in the longitudinal direction, on the knife shafts  22 ,  24  and on them tools (not shown) for cutting, cutting out, perforating, crimping etc. a sheet leaving the buckle plate  12  are arranged. The knife shafts  22 ,  24  are mounted in a cassette  28 , the design of which will be explained in greater detail below. The cassette  28  itself is arranged on a drawer  30  which can be pulled out of the folding machine  10  through an opening in the sidewall  20  facing the operator until the entire cassette  28  is outside the folding machine  10 . This position is shown in FIG.  1 . 
     FIG. 2  shows the position of the drawer  30  in which it is inserted completely into the folding machine  10 . In this case, the drawer  30  bears with its end wall  34  facing the drive against the sidewall  18  facing the drive. The drawer  30  extends completely between the two side walls  18 ,  20 . The drawer  30  rests on a horizontal base  32  which extends between the side walls  18 ,  20 . To guide the movement of the drawer  30  from the inserted position into the pulled-out position, guide means (not shown) are provided which guide the drawer  30  in such a manner that it executes a rectilinear movement. As such a guide for a drawer  30 , use can be made, for example, of two three-part telescopic guides which are connected to one another by a drawer base and, in the inserted state, are arranged completely between the machine side walls. The cassette  28  is inserted loosely into the drawer  30 . 
   The cassette  28  with the knife shafts  22 ,  24  arranged parallel to each other on it is shown in greater detail in  FIGS. 3  to  5 ,  8  and  9 . The cassette  28  has an end wall  34  facing the drive and an end wall  36  facing the operator, said end walls being connected to each other by crosspieces  38 ,  40 . The two knife shafts  22 ,  24  are mounted rotatably, for example via plug-in spindles or half-shells, in knife shaft mountings  42 ,  44  on the operator side. The upper mounting  42  can be displaced in a plane defined by the two shaft axes or is designed such that it can be rotated about an eccentric point in order to make it possible to set the nip between the two knife shafts  22 ,  24 . 
   As can be seen in  FIGS. 8 and 9 , the knife shafts  22 ,  24  are mounted rotatably on the drive side by bearing devices  46 ,  48 , the bearing devices  46 ,  48  being designed simultaneously as a rotary leadthrough and coupling element which are connected in a rotationally fixed manner to a drive element of the folding machine when the cassette  28  is inserted into the folding machine  10 . The upper bearing device  46  can be displaced in the plane defined by the two shaft axes while the lower bearing device  48  is arranged in a fixed manner. 
   The upper bearing device  46  has a bearing shell  60  in which a ball bearing  64  through which the shaft  22  passes is arranged. The bearing shell is guided along a straight line, which passes through the center axes of the shafts  22 ,  24 , through two guide blocks  68 ,  70  arranged on both sides. One end of a threaded pin  73  engages in the upper side of the bearing shell  60 . The other end is in engagement with a threaded opening which is formed in a threaded block  72  which is fastened to the sidewall  34  adjacent to the upper edge thereof. The threaded pin  73  is accessible from above via an opening in the threaded block  72 , and can be rotated by means of a suitable tool in order to set the nip between the two knife shafts  22 ,  24 . 
   The lower bearing device  48  has a bearing block  62  which is fastened to the sidewall  34  and in which a ball bearing  66  through which the shaft  24  passes is arranged. 
   As can be seen in  FIG. 9 , coupling sections  74 ,  76  are provided at that end of the knife shafts which faces the drive, said coupling sections being used to connect the knife shafts to drive elements on the folding machine  10  when the cassette  28  is in the position shown in  FIG. 2 , the coupling sections  76 ,  78  being designed in such a manner that an axial or radial offset is compensated for and the torque is introduced in a positive-locking manner. 
   Above the upper knife shaft  22 , a fixing pin  50  which protrudes toward the end wall  34  facing the drive is provided on the end wall  36  facing the operator. In the inserted position of the cassette  28  which is shown in  FIG. 2 , this fixing pin  50  engages in a centering opening in the outside of the sidewall  20 . As can also be seen in  FIG. 2 , the end wall  36  facing the operator rests with its edge on the sidewall  20 . A further fixing pin  51  extends outward from the end wall  34  facing the drive. In the inserted position of the cassette  28  shown in  FIG. 2 , this fixing pin  51  engages in a centering opening in the inside of the sidewall  18 , as a result of which the cassette is automatically aligned. 
   The tool holders  26  are fitted releasably on the shaft body  23  of the knife shafts  22 ,  24 . Precise positioning of the tool holders  26  on the knife shafts  22 ,  24  is made possible by a scale, as is shown in  FIGS. 6 and 7 . A vernier is engraved into the surface of the shaft body  23  of the knife shafts  22 ,  24  in the longitudinal direction of the knife shafts  22 ,  24  as the scale  52 . Owing to the precise scale  52  directly on the knife shaft  22 ,  24 , it is possible to fasten a tool holder  26  on the knife shaft  22 ,  24  in a precise manner. The fastening accuracy is additionally increased by the fact that it is possible for an operator to fasten the tool holders  26  to the knife shafts  22 ,  24  outside the folding machine  10 . This avoids parallax errors.