Abstract:
A method and an installation operable for cleaning an inking blade acting against a chambered printing cylinder of a flexographic printing machine. A cleaning device includes a blade cleaner, a recovery device for ink removed from the blade, a first prewash cleaning system, a subsequent regular wash system and an air nozzle system to clean out ink. The ink is recovered before the washing. The ink washed out is recovered and this polluted wash fluid is used in a subsequent cleaning as a prewash.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a 35 U.S.C. §§ 371 national phase conversion of International Application PCT/EP2006/008914, filed Sep. 13, 2006, which claims priority of European Patent Application No. 05019937.1, filed Sep. 13, 2005, the disclosures of which have been incorporated herein by reference. The PCT International Application was published in the French language. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an installation for changing ink in a printing station of a flexographic printer. 
         [0003]    Known installations intended for changing ink in the various printing units of a flexographic printing machine usually comprise means for cleaning various inking members coupled with means to refill the inking circuit, usually with an ink of another color. Presently, cleaning the printing members of flexographic printing machines is done in a manner familiar to practitioners, by circulating water through the piping of the inking circuit and through the chambered doctor blade, using the ink pump. This cleans all the inking members as well as the screened ink transfer cylinder. However, some of the inking members, in particular the chambered doctor blade, need the most perfect cleaning possible to avoid mixing new ink with residues of ink color previously used. This cleaning operation makes use of a very large quantity of cleaning fluid, usually water. 
       DESCRIPTION OF THE PRIOR ART 
       [0004]    European Patent EP-B-0,687,563 describes in detail a cleaning device, which washes the inking members of such a printing machine. This device makes cleaning operations easier by suppressing any manual cleaning of the printing members of the rotary printing machine. But, the problem of reducing the quantity of cleaning fluid is not solved, because to have acceptable cleaning, it is necessary to perform a great number of runs of the cleaning device over the chambered doctor blade. This causes very high consumption of cleaning fluid. Independently of that, residual ink contained in the various inking piping is also to be eliminated. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to change ink in a printing unit of a flexographic printing machine, including cleaning of the chambered doctor blade to allow better elimination of the ink remaining in the chambered doctor blade before the cleaning fluid is used up. 
         [0006]    This object is achieved by using a method and an installation operable for cleaning the inking blade acting against the chambered printing cylinder of a flexographic printing machine. A cleaning device includes a blade cleaner, a recovery device for ink removed from the blade, a first prewash cleaning system, a subsequent regular wash system and an air nozzle system to clean out ink. The ink is recovered before the washing. The ink washed out is recovered and the polluted wash fluid is used in a subsequent cleaning as a prewash. 
     
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         [0007]    The invention is now described with reference to a non-limiting embodiment and is illustrated in the appended drawings in which: 
           [0008]      FIG. 1  is a schematic view in partial section of a first version of a cleaning installation of an inking unit of a flexographic printing machine, 
           [0009]      FIG. 2  is a schematic view, in partial section of a second version of a cleaning installation of the inking unit of a flexographic printing machine, 
           [0010]      FIG. 3  is a schematic view showing the inking of a chambered doctor blade, 
           [0011]      FIG. 4  is a schematic view, showing ink recovery from a chambered doctor blade, 
           [0012]      FIG. 5  is a schematic view, showing prewashing of the chambered doctor blade with a dirty cleaning fluid which has been recovered from a previous cleaning, 
           [0013]      FIG. 6  is a schematic view, showing the cleaning of the chambered doctor blade with a clean cleaning fluid, 
           [0014]      FIG. 7  is a section view of the washing member of the chambered doctor blade and, 
           [0015]      FIGS. 8A and 8B  are each sectional views of the rotary nozzle of the washing member of  FIG. 7 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]      FIG. 1  is a schematic view in partial section of the inking unit of a flexographic printing machine. This printing unit  1  comprises a plate cylinder  2 , which is inked by a celled cylinder  3 , known by practitioners as an anylox cylinder. This celled cylinder  3  is fed with ink by a chambered doctor blade  4 , represented here by mixed dashed lines in its inking position. The inking unit  1  also comprises a cleaning device  5  for the inking means, that is for the celled cylinder  3  and the chambered doctor blade  4 . The cleaning device  5  is described below in detail with reference to  FIG. 7 . A recovery container  6  is arranged under the inking members near the cleaning device  5 . The inking members extend between two side frames  7 , respectively  8 . The chambered doctor blade  4  is connected to two levers, not represented, to allow the blade to pivot from its inking position to a cleaning position depicted here by the reference  9 . In this implementation, the cleaning device  5  comprises a recovery member  44  operable for recovering the ink contained in the chambered doctor blade. The device  5  is comprised of a rotary nozzle  21  coupled to a stationary nozzle  100  (see  FIG. 7 ). 
         [0017]      FIG. 2  is a schematic view in partial section of a second version of a cleaning installation of the inking unit of a flexographic printing machine. In this version, the inking unit  1  comprises a plate cylinder  2  which is inked by a celled cylinder  3 , known by practitioners as an anylox cylinder. This celled cylinder is fed ink by a chambered doctor blade  4 , represented here by mixed dashed lines in its inking position. The inking unit  1  also comprises a cleaning device  5  for the inking members, that is, for the celled cylinder  3  and the chambered doctor blade  4 . A recovery container  6  is arranged under the inking members near the cleaning device  5 . The inking members extend between two side frames  7 , respectively  8 . The chambered doctor blade  4  is connected to two levers, not represented, to allow it to pivot from its inking position to a cleaning position depicted here by the reference  9 . In this implementation, the cleaning device  5  includes a recovery member  45  for recovery of the ink contained in the chambered doctor blade. The cleaning device is comprised of an ink knife having a shape closely matching the inside profile of the chambered doctor blade  4 , so as to be able to recover as much as possible of the ink in the chambered doctor blade  4 . This solution allows a mechanical recovery of the ink contained in the chambered doctor blade during movement of the ink knife along the chambered doctor blade  4 . 
         [0018]      FIG. 3  is a schematic view representing inking of the chambered doctor blade  4  which is in contact at this stage of process with the celled cylinder  3 . For this operation, the installation for changing ink comprises a bi-directional pump  10 . It is brought near an ink storage  11  so as to be able to feed the chambered doctor blade  4  with ink via a supply piping  12 . The bi-directional pump  10  pushes the ink in the supply piping  12  in the direction indicated by the arrow  15 . The inking circuit of the chambered doctor blade comprises a return piping  13  linking the chambered doctor blade to the ink storage  11 , for ink return in the direction indicated by the arrow  16 . A supply piping  17  for the cleaning fluid is linked to the piping  12  supplying ink to the chambered doctor blade  4 . This supply piping  17  of the cleaning fluid is fitted with a valve  18  which is in a closed position during feeding of ink to the chambered doctor blade  4 . The installation for changing ink also comprises means to move the piping  13 , automatically in due course, over a recovery tank  14  for the cleaning fluid as explained below. 
         [0019]      FIG. 4  is a schematic view representing ink recovery from the chambered doctor blade. To prepare for a new job requiring an ink of a different color in the printing units of the machine, the operator proceeds with cleaning of the printing members. For that, it is necessary to first recover the ink contained in the chambered doctor blade  4 . This operation is performed with the chambered doctor blade in its inking position, i.e. with the chambered doctor blade  4  in contact with the celled cylinder  3 , as represented in  FIGS. 1 and 2 . The pumping direction of the bi-directional pump is reversed with respect to the direction earlier indicated by the arrow  15 , to supply ink from the chambered doctor blade  4  to the ink storage  11  in the direction indicated by the arrow  19  in  FIG. 4 . The ink contained in the back piping  13 , partly in the chambered doctor blade  4  is also supplied by gravity to the ink storage  11  in the direction indicated by the arrow  20 . After the ink contained in the chambered doctor blade  4  has been removed, some ink marks still remain in the chambered doctor blade  4 . It is desirable to eliminate these ink residues. For that purpose, the chambered doctor blade  4  is pivoted into the cleaning position  9  (see  FIG. 1 ). The cleaning device  5  is brought over the chambered doctor blade  4  and, for a first time, the stationary nozzle  100  at the rotary nozzle  21  (see  FIG. 7 ), is fed with gaseous fluid, for example compressed air, and is moved along the chambered doctor blade in order to force the residual ink remaining in the chambered doctor blade  4  to flow out of the blade and into the ink storage  11 , alternately by the back piping  13  and by the supply piping  12 . The blowing operation on the residual ink can be repeated several times, as a function of the chosen cleaning program. 
         [0020]      FIG. 5  is a schematic view representing prewashing of the chambered doctor blade with a dirty washing fluid that had been recovered from a preceding washing, for example the one described in relation to the  FIG. 6 . The valve  18  is closed. Polluted washing fluid then in the recovery tank  14  is pushed into the chambered doctor blade  4  by the bi-directional pump  10  in the direction indicated by the arrow  24 , and this pushes the polluted washing fluid to the factory wastewater treatment station using pressure and through the back piping  13 , in the direction indicated by the arrow  25 . After this prewashing operation, washing of the chambered doctor blade  4  can thus proceed, such as by the process described in relation to  FIG. 6 . 
         [0021]      FIG. 6  is a schematic view representing the washing of the chambered doctor blade with a clean washing fluid. After the operation described in relation to  FIG. 5  has finished, the feeding of compressed air has been stopped, the rotary nozzle  21  of the washing means is fed with clean washing fluid, and the nozzle is moved again along the chambered doctor blade  4 , still in washing position, so as to be able to rinse the inside of the chambered doctor blade  4  with washing fluid. As thus represented in  FIG. 6 , the installation for changing ink has been moved to be positioned at the recovery tank  14  of the washing fluid. The valve  18  of the supply piping  17  of the cleaning fluid  17  is opened and the bidirectional pump  10  is actuated to push this washing fluid in the direction indicated by the arrow  22 , in the direction of the chambered doctor blade  4 . The return of the washing fluid in the direction of arrow  23  is assured using the back piping  13 . This operation lasts as long as necessary to completely eliminate all the ink residues from the inking circuit. The valve  18  is then closed, and the polluted washing fluid is stored in the recovery tank  14 , available for a subsequent prewashing use in the chambered doctor blade  4 . This process allows use of this polluted washing fluid during a further washing operation of the chambered doctor blade. The prewashing of the chambered doctor blade saves a significant quantity of clean washing fluid by starting the cleaning operation using this polluted fluid instead of starting with a clean washing fluid which is also to be used afterwards. 
         [0022]    The installation for changing ink comprises also standard means to clean the other inking members, such as means mentioned in the preamble of the present patent application in relation with the European patent EP-B-0,687,563. 
         [0023]      FIG. 7  is a cross-sectional view of a cleaning device  5  for a chambered doctor blade  4  according to the version represented by  FIG. 1 . This cleaning device  5  comprises a washing head  26  formed by a box  27  comprising a sole plate  28  crossed by a supply piping  29  for supplying a cleaning fluid and compressed air to the rotary nozzle  21  and the stationary nozzle  100 . The sole plate  28  is fitted with a brush  30  which has bristles preferably perfectly matched to the outside profile of the chambered doctor blade  4 . The washing head  26  is arranged so as to be able to pivot from a horizontal position to a contact position with the chambered doctor blade  4 . The washing head  26  is mounted at one end of an arm  31 . The other end is pivotably mounted in a bearing  32 , in particular comprising ball bearings  33  and  34 . A spindle  35  is attached at the lower portion of the bearing  32  by mean of screws  36  and  37 . The spindle  35  is mounted on ball bearings  39  and  40  so as to be able to pivot in a block-bearing  38 , thus allowing horizontal rotation of the arm  31  supporting the washing head  26 . The block-bearing  38  is connected to a support  41  having one end attached on a carriage  42 , which is able to transversely move along the chambered doctor blade  4  under the action of a pneumatic cylinder  43  or of another similar member. Feeding of cleaning fluid to the rotary nozzle  21  is through the piping  46  for injecting the cleaning fluid up to the rotary nozzle  21  through the boring  47  of the spindle  35  emerging in the boring  48  provided in the arm  31 . Feeding of the stationary nozzle  100  and of the rotary nozzle  21  with compressed air is ensured via the pipe  49 . Rotation of the rotary nozzle  21  around the piping  29  occurs under the action of cleaning fluid ejected through the slots  50  of the rotary nozzle  21  (see  FIG. 7 ). After the cleaning operations of the chambered doctor blade  4  have been completed, the washing head  26  is pivoted so as to disengage it from the chambered doctor blade, and the arm  31  is pivoted on the spindle  35  in a manner to bring the cleaning member  5  in an out of work position allowing the chambered doctor blade  4  to pivot to bring it into contact with the celled cylinder  3  to re-feed the chambered doctor blade  4  with an ink of a different color. 
         [0024]      FIGS. 8A and 8B  are views of the rotary nozzle  21  of the cleaning device  5  of  FIG. 7 . The rotary nozzle is represented in two different positions so as to show the positioning of the slots  50  around the rotary nozzle  21 . The slots  50  have a particular shape so that the action of the cleaning fluid causes the rotary nozzle  21  to move around the piping  29  (see  FIG. 6 ) passing through the boring  51  of the rotary nozzle  21 . 
         [0025]    A benefit provided by the present invention is mainly the saving of cleaning fluid due to the fact of the recovery of polluted cleaning fluid in the recovery tank  14 , to use it afterwards as prewashing fluid for the chambered doctor blade  4  and in a more full recovery of the ink remaining in the chambered doctor blade. A washing cycle begins by first using polluted fluid and afterwards using clean fluid. 
         [0026]    Numerous improvements can be brought to the present invention within the scope of the claims. 
         [0027]    Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.