Patent Abstract:
Method for loading and exchanging the rollers of the printing units of a printing machine and a device for working the method, the device loading station including a handling carriage for engraved rollers, a storage station for rollers, a reserve station at each of the printing units, a robot for transporting the engraved rollers, either from the loading station or from the storage station to a ready position located in the reserve station. The robot takes an engraved roller either from a reserve position or from the storage station or from the loading station and brings the roller into a working position. The robot is also able to withdraw an engraved roller from its working position in order to bring it either into a reserve position, or into the storage station or into the loading station.

Full Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method for loading and exchanging the rollers of the printing units of a printing machine and to a device for working the method.  
           [0002]    Generally, a printing machine comprises a plurality of printing units arranged one after another in the case of a flexographic printing machine in line, for example. In this kind of machines, each printing unit comprises a plate cylinder on which the ink is deposited by an engraved roller, commonly called “anilox cylinder” by workers in the art. This engraved roller is supplied with ink, in well known manner, either by means of a doctor blade chamber or an inking roller associated with an ink pan. The plate cylinder prints directly, by contact, the matter to be printed, by using a pressure roller applying the matter to be printed against the plate cylinder. The engraved rollers include, at their circumference, cells intended to retain the ink having to be deposited on the printing plate of the plate cylinder. The volume per surface unit of these cells varies according to the jobs to be performed. Thus, the use of different engraved rollers for each specific job to be performed will be necessary. That means that these engraved rollers have to be exchanged according to the desired printing quality, an engraved roller used for a print including large “tint blocks”, i.e. large surfaces uniformly supplied with ink, will not be appropriate for fine prints not including large “tint blocks”.  
           [0003]    Exchange solutions of an engraved roller have already been proposed. One of these solutions is described in patent CH 686 355 A5. In this patent, the exchange of the engraved roller is carried out by means of a carriage comprising engraved roller supports. In order to exchange an engraved roller, this carriage is laterally introduced between two printing units and the engraved roller, having been previously withdrawn from its bearings, is brought to the level of the engraved roller supports of the carriage. The carriage can be built in various ways and include either a lifting system with cross-pieces or actuators acting directly on the vertical movement of the engraved roller supports. The engraved roller having been brought to the level of the engraved roller supports, the latter are moved to the top so as to come into contact with the engraved roller in order to support it. The carriage is then laterally withdrawn from between the printing units and brought, outside the machine, towards a processing station where the used engraved roller can be removed and replaced by a new engraved roller. The replacement of the engraved roller having been carried out, the carriage is again introduced between the printing units and the new engraved roller is placed by repeating, in the reverse order, the same operations as for its withdrawal from the printing unit. Another solution, substantially identical to that described herebefore, is described in European patent EP 0 401 636 B1.  
           [0004]    The two above-mentioned solutions present the drawback that the operator is obliged to get in between the printing units for exchanging the engraved rollers, thus requiring his particular attention as regards his security. Another drawback lies in the fact that the exchange of the engraved rollers is a relatively long operation, during which the machine is at standstill so that its productivity is reduced accordingly.  
         SUMMARY OF THE INVENTION  
         [0005]    The aim of the present invention is to eliminate the aforesaid drawbacks by proposing a method and a device for exchanging the rollers of the printing units of a printing machine in which the security of the operator is ensured in the most perfect possible way while reducing to the maximum the time necessary for the exchange operation of the engraved rollers.  
           [0006]    To this end, the method according to the invention comprises the following stages:  
           [0007]    a) for the loading of the engraved rollers in a storage station, in reserve stations and in a working position in the printing units:  
           [0008]    to bring firstly, by means of a handling carriage, a first engraved roller into a loading station located at the entry of a feeder;  
           [0009]    to bring, by means of a robot, the engraved roller, taken from the loading station, either into the storage station located in the lower part of the feeder, or into one of the reserve stations located in one of the printing units, or into an unloading position of one of the printing units;  
           [0010]    to bring then by means of the handling carriage, previously reloaded, a second engraved roller into the loading station;  
           [0011]    to bring, by means of the robot, the second engraved roller, taken from the loading station, either into the storage station located in the lower part of the feeder, or into one of the reserve stations located in one of the printing units;  
           [0012]    to bring then by means of the handling carriage, previously reloaded, an umpteenth engraved roller into the loading station;  
           [0013]    to introduce, by means of the robot, the umpteenth engraved roller, taken from the loading station, either into the storage station located in the lower part of the feeder, or into one of the reserve stations located in one of the printing units;  
           [0014]    to introduce, by means of the robot, one of the engraved rollers taken either from the handling carriage, previously reloaded or from the storage station or from one of the reserve stations located in one of the printing units, on a transport device which will bring it into its working position, in its respective printing unit;  
           [0015]    to position and to fix the engraved roller in its working position in its respective printing unit;  
           [0016]    b) for the exchange of an engraved roller of one of the printing units:  
           [0017]    to withdraw the engraved roller to be exchanged from its working position;  
           [0018]    to bring, by means of the transport device, the engraved roller to be exchanged into an unloading position;  
           [0019]    to bring, by means of the robot, the engraved roller to be exchanged, from the unloading position, either to a free location of the reserve station of the printing unit concerned, or to bring it, always by means of the robot, to a free location of the storage station, or to bring it, always by means of the robot, onto the handling carriage previously unloaded;  
           [0020]    to take, by means of the robot, the engraved roller of replacement, either in the reserve station of the printing unit concerned, or in the storage station, or on the handling carriage;  
           [0021]    to bring, by means of the robot, the engraved roller of replacement onto the transport device which will bring it into its working position and to fix the engraved roller of replacement in its working position.  
           [0022]    The device for loading and exchanging the rollers of the printing units of a printing machine for working the foregoing method comprises a loading station, including a handling carriage for engraved rollers, followed by a storage station of engraved rollers, reserve stations arranged in each printing unit, means for transporting the engraved rollers, either from the loading station, or from the storage station to a ready position located in the reserve station of one of the printing units, the said means for transporting the engraved rollers being arranged so as to be able to take an engraved roller either from a reserve position, or from the storage station or from the loading station in order to bring it into its working position, the said means for transporting the engraved rollers being also arranged so as to be able to withdraw an engraved roller from its working position in order to bring it indifferently either into a reserve position, or into the storage station or into the loading station, and also comprises control means for said means for transporting the engraved rollers.  
           [0023]    According to an advantageous embodiment, the means for transporting the engraved rollers consist of a transport device working conjointly with a robot.  
           [0024]    According to another embodiment, the robot is arranged so as to be movable on rails arranged parallely between lower parts of the printing units, one of these rails including a rack in which engages a pinion of a gear box coupled with a gear motor.  
           [0025]    According to another advantageous configuration, the robot comprises a lifting device consisting of “X” levers fixedly attached to a bedplate, the said levers supporting a base provided with support members for the engraved rollers. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    The invention will be more readily understood from the following description of an embodiment which is given by way of non-limitative example and illustrated in the accompanying drawings wherein:  
         [0027]    FIGS.  1  to  19  schematically illustrate the various stages of a method for exchanging the engraved rollers of a flexographic printing machine (for reasons of clearness, the reference numerals identical to those of FIG. 1 have not been indicated on FIGS.  2  to  19 ),  
         [0028]    [0028]FIG. 20 is a perspective view of the lower part of a flexographic printing machine,  
         [0029]    [0029]FIG. 21 is a perspective view of a member for loading and unloading the engraved rollers, and  
         [0030]    [0030]FIG. 22 is a perspective view of a handling carriage for engraved rollers. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    [0031]FIG. 1 schematically illustrates a flexographic printing machine comprising a feeder  1  followed by printing stations or printing units  2 ,  3 ,  4   5 . The printing station  5  is as for it followed by a delivery station  6 . The sheets to be printed, not shown, are conveyed through these various stations by means of suction conveyors  7 . Each printing unit  2  to  5  includes a printing cylinder  8 , a pressure roller  9  and an engraved or “anilox” roller  10 . Each printing unit  2  to  5  also includes a reserve station  11  for engraved rollers  17 . Each of these printing units  2  to  5  is also equipped with a transport device  13  for the engraved rollers  10  in operation in its respective printing unit. This transport device  13 , of well known construction, can be associated with a device of engagement and release of the bearings of the engraved rollers  10 , which device is also well known und thus not shown on this figure. A storage station  14  is also arranged in the lower part of the feeder  1 . In the present embodiment, this storage station  14  includes locations for four engraved rollers  17 . Obviously, this number is not restrictive and a number either more restricted or more important of locations for the engraved rollers in the storage station  14  would be possible. Also, the flexographic printing machine is preceded by a loading station  16  of engraved rollers  17 . This loading station  16  is equipped with a handling carriage  18  which can manually or automatically be inserted in or withdrawn from this loading station  16 . The flexographic printing machine shown on this figure further comprises a robot  19 , shown here in the rest position  19   a , intended for the exchange of the various engraved rollers  10  of the printing units  2  to  5 . In this figure, the flexographic printing machine is shown in operation, i.e. all the engraved rollers  10  are in operating contact with their respective printing cylinders  8 .  
         [0032]    [0032]FIG. 2 illustrates the flexographic printing machine of FIG. 1 in the exchange phase of the engraved roller  10  of the printing unit  2 . This exchange of the engraved roller  10  is required at the time of a job change obliging the use of an engraved roller  17  having a cell configuration more adequate than the cell configuration of the engraved roller  10  to carry out the new job. As shown in FIG. 2, the engraved roller  10 , the bearings of which having been released from their housings in the side frames of the printing unit  2 , either manually or automatically by means of a known device, e.g. a releasing device for bearings by unlocking and swivelling, is removed from its working position  10   a  by the transport device  13  to an unloading position  10   b.    
         [0033]    [0033]FIG. 3 illustrates one of the following stages of the exchange of the engraved roller  10 , in particular the stage in which the robot  19  starts to move towards the printing unit  2 , in the direction shown by arrow  20 .  
         [0034]    [0034]FIG. 4 shows the robot  19  which has moved so as to occupy the position  19   b  in the printing unit  2 .  
         [0035]    [0035]FIG. 5 represents the robot  19  in the position  19   b  after its lifting device  21  has been actuated so that its support member  23  of the engraved roller  10  comes to be placed under the lower level of the engraved roller  10 . Then, as shown in FIG. 6, the robot  19  is moved in a position  19   c , in the direction shown by arrow  22 . Its lifting device  21  is again actuated so that the support member  23  is brought in contact with the engraved roller  10 . The following stage consists, as shown in FIG. 7, to move the robot  19  loaded with the engraved roller  10 , in the direction shwon by arrow  24 , to the position  19   b  which it occupied before (see also FIGS. 4 and 5). Always in this position  19   b , the lifting device  21 , supporting the engraved roller  10 , is then lowered as shown in FIG. 8.  
         [0036]    [0036]FIG. 9 represents the robot  19  in the following stage, i.e. in the position  19   d , during which it is moved, always with its lifting device  21  in lowered position, into the printing unit  2 . In this position  19   d , the robot  19  has brought the engraved roller  10  vertically to a storage position  25  of engraved rollers located in the reserve station  11 . The lifting device  21  of the robot  19  is now controlled so that it is moved vertically in the direction of the storage position  25  in which the engraved roller  10  is deposited on side supports, not shown here, of the reserve station  11 . This arrangement is illustrated in FIG. 10.  
         [0037]    As represented on FIG. 11, the robot  19  is then moved in the direction shown by arrow  26  to a position  19   e  in which the support member  23  of the lifting device  21  is vertically to the storage location of a new engraved roller  17  intended to replace the engraved roller  10  which has been withdrawn from its working position  10   a . Always in the position  19   e , the lifting device  21  is controlled so as to be moved vertically towards the engraved roller  17  being in its storage position  27  in the reserve station  11 , until that the support member  23  comes into contact with the engraved roller  17 , as shown in FIG. 12. At this moment, the lifting device  21  supporting the engraved roller  17  is lowered (see FIG. 13) and the robot  19  is moved in the direction shown by arrow  28  (see FIG. 14) to the position  19   b  which it occupied already before at the time of the exchange operation of the engraved roller  10  (see also FIGS. 4, 5 and  8 ). The lifting device  21  of the robot  19  is then actuated vertically so as to bring the engraved roller  17  in the vicinity of the transport device  13 , as shown in FIG. 15.  
         [0038]    [0038]FIG. 16 shows that the robot  19  is then moved again, in the direction shown by arrow  29 , to the position  19   c  which is identical to the position that it occupied in the description of FIG. 6. The engraved roller  17  is then deposited in the position  17   b  on the entry of the transport device  13 . Referring now to FIG. 17, the robot  19  is moved again, in the direction shown by arrow  30 , to the position  19   b  (see also FIGS. 4, 5,  7 ,  8 ,  14  and  15 ), then actuated downwards so as to occupy the location which it occupied in FIGS. 8 and 14. The robot  19  can then finally be moved, in the direction shown by arrow  31 , to its rest position  19   a . The replacement of the engraved roller  10  by a new engraved roller  17  in the printing unit  2  has just been described. In this operation, the new engraved roller  17  has been taken from the reserve station  11  of this printing unit  2 . However, it might of course be considered, according to the inherent needs in a given job, to take a new engraved roller from any reserve station  11  of the other printing units  3  to  5  or from the storage station  14  located under the feeder  1  or even from the handling carriage  18  located in the loading station  16 , by bringing the robot  19  in a position  19   f , such as shown in short dashes on FIG. 19, so that it can take another engraved roller  17 . It might also be considered to equip all the reserve stations  11  with two engraved rollers  17  and to leave free a location for engraved roller either in the storage station  14  located under the feeder  1 , or on the handling carriage  18  placed in the loading station  16 . In this possibility, it is obvious that the control of the robot  19  should correspond to the choice of one or the other of the solutions adopted for the exchange of the engraved rollers. In the just described example, i.e. the replacement of the engraved roller  10  of the printing unit  2  by an engraved roller  17  taken from the reserve station  11  of said printing unit, this replacement can be carried out “in masked time”, i.e. without the flexographic printing machine being stopped. In this case, it is possible to carry out a job requiring only the use of the printing units  3  to  5 .  
         [0039]    An example of embodiment of a device for working the method will now be described in reference with FIGS.  20  to  22 .  
         [0040]    [0040]FIG. 20 is a perspective view of the lower part  32  of a flexographic printing machine comprising five printing units  2 ,  3 ,  4 ,  5  and  33  preceded by a feeder  1 . Each printing unit  2 ,  3 ,  4 ,  5  and  33  is formed with two side frames of which only the lower parts  34  have been represented on this figure. The feeder  1  is also formed with two side frames, only the lower parts  35  of which, constituting the storage station  14 , have been represented. Each lower part  34 , respectively  35  is equipped with support members  36  adapted to receive the ends of the engraved rollers (not shown on this figure). In the chosen example, the lower parts  34  include each two support members  36  whereas the lower parts  35  of the storage station  14  include four. The lower parts  34 ,  35  are mounted on an alignment rail  37 , respectively  38 . The device further comprises two running rails  39  and  40 , one of which, the running rail  40 , being provided with a rack  41 . These two running rails  39  and  40  are adapted to be used as guide for the robot  19  represented here in position in the printing unit  33 . The handling carriage  18 , which is not shown on the figure, will be placed in the area  42  located right before the storage station  14  arranged at the lower part of the feeder  1 .  
         [0041]    [0041]FIG. 21 is a perspective view of a loading and unloading member of engraved rollers  17 , defined in this description, as being robot  19 . This robot  19  consists of a bedplate  43  comprising at its front and rear parts a safety device  44 . The bedplate  43  is arranged so as to support the lifting device  21  consisting of an elevator formed with “X” levers  45  and  46  supporting a base  47  on which a support member  23  for the engraved rollers is fixed. This support member  23  consists here of two parts in V  48  and  49 . The elevator of the lifting device  21  is controlled by means of a motor  50  acting on a control screw  51  engaging in a nut disposed in the crossbar  52  connecting the two lower ends of the levers  46 . The bedplate  43  is moreover equipped with a gear motor  53  coupled to a gear box  54  one of the pinion of which (not shown) engages within the rack  41  of the running rail  40  of FIG. 20. The control of the motor  50  of the elevator of the lifting device  21  as well as the control of the gear motor  53  intended to ensure the movement of the robot  19  are performed by means of a computer program whose program steps are defined according to the various movements mentioned in connection with the description of FIGS.  1  to  19 .  
         [0042]    [0042]FIG. 22 is a perspective view of a handling carriage  18  for an engraved roller  17 . This handling carriage  18  consists of a frame  54  equipped with directional casters  55  as well as two centering and guiding discs  56  allowing the accurate positioning of the handling carriage  18  in the loading station  16 , that on a slide (not shown) of well known manufacture comprising, for example, two guiding rails adapted to receive the two centering and guiding discs  56 .  
         [0043]    A thus composed handling carriage  18  enables the operator to move the engraved roller  17 , carried by the handling carriage, towards a workstation, located outside the machine, in which various operations, for example washing operations, could be carried out.

Technology Classification (CPC): 1