Abstract:
A method for operating a dampening system of a printing group of a printing machine, especially a web-fed rotary printing press, the dampening system comprising a dampening means dosing device provided with a plurality of dosing units, a dampening system rolling mill drive having at least one dampening system roller, and at least one dampening means application roller. The application of the dampening means is adapted to the width of the material to be printed or to widths of the sides of the material to be printed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a U.S. National stage of International Application No. PCT/EP2007/010136, filed on 22 Nov. 2007. Priority is claimed on German Application No. 10 2006 055 584.8, filed on 24 Nov. 2006, the content of both being incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention pertains to a method for operating a dampening unit of a printing couple of a printing press. The invention also pertains to a dampening unit and to a printing couple. 
         [0004]    The printing couples of printing presses have a form cylinder, a transfer cylinder that rolls on the form cylinder, an impression cylinder that rolls on the transfer cylinder, an inking couple, and a dampening unit. The inking couple is used to transfer printing ink to the form cylinder, to at least one printing form positioned thereon, which carries the page to be printed. With the help of the dampening unit, dampening solution can be applied to the printing form or forms arranged on the form cylinder. The form cylinder is also called a “plate cylinder”. 
         [0005]    At least one blanket positioned on the transfer cylinder transfers the ink to a substrate, where the substrate can be moved through a nip formed between the transfer cylinder and the impression cylinder. The transfer cylinder is also called a “blanket cylinder”. 
         [0006]    In the case of web-fed rotary printing presses, several printing couples are usually combined into a printing unit, where, in this case, the impression cylinder of a printing couple of a printing unit is designed either as a so-called “satellite cylinder”, which rolls on several transfer cylinders of different printing couples of the printing unit, or as a transfer cylinder of a different printing couple of the printing unit. 
         [0007]    The dampening unit is used to apply dampening solution to the printing form or to each printing form positioned on the form cylinder, where a dampening unit comprises a dampening solution metering device comprising several metering units; the metering device applies dampening solution to a dampening roller of a dampening roller train directly downstream of the dampening solution metering device. The dampening roller or each dampening roller of the dampening roller train conveys the dampening solution to at least one dampening form roller, which rolls on the form cylinder and thus ultimately applies the dampening solution to the printing form or to each printing form positioned on the form cylinder. 
         [0008]    The application of the dampening solution to the printing form on to each printing form positioned on the form cylinder must be adapted to the width of the pages to the printed in order to ensure optimum print quality. It should be noted that a printing form can be used for the printing of one or more pages. When a printing form is used to print several pages, these several pages can be arranged either next to each other in the axial direction of the form cylinder or one behind the other in the circumferential direction. 
         [0009]    In cases where it is desired to produce different printed products which differ with respect to the width of the pages to be printed or with respect to the width of the substrate to be printed, the application of the dampening solution presents difficulties with respect to optimum print quality. 
       SUMMARY 
       [0010]    The present invention relates to creating a novel method for operating a dampening unit of a printing couple, a novel dampening unit, and a novel printing couple in order to make optimum print quality possible. 
         [0011]    The application of the dampening solution is adapted to the width of the substrate or to the widths of pages to be printed on the substrate. 
         [0012]    In accordance with one embodiment of the present invention, the application of dampening solution of a dampening unit is adapted to the width of the substrate or to the widths of the pages to be printed. As a result, it is possible to achieve optimum print quality. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Preferred elaborations of the invention can be derived from the subclaims and from the following description. Exemplary embodiments of the invention, which are not intended to limit the invention, are explained in greater detail below on the basis of the drawings: 
           [0014]      FIG. 1  is a schematic diagram of a printing couple; 
           [0015]      FIG. 2  is a form cylinder of a printing couple with four printing forms arranged on the form cylinder for the printing of relatively wide pages; 
           [0016]      FIG. 3  is a form cylinder of a printing couple with four printing forms arranged on the form cylinder for the printing of relatively narrow pages; 
           [0017]      FIG. 4  is a schematic top view of part of an inventive dampening unit according to a first exemplary embodiment of the invention in the area of a dampening solution metering device and of a dampening roller directly downline therefrom; 
           [0018]      FIG. 5  is a side view of the part shown in  FIG. 4 ; 
           [0019]      FIG. 6  is a schematic top view of part of an inventive dampening unit according to a second exemplary embodiment of the invention in the area of a dampening solution metering device and of a dampening roller immediately downstream thereof; 
           [0020]      FIG. 7  is a side view of the part shown in  FIG. 6 ; 
           [0021]      FIG. 8  is a detail of the part shown in  FIG. 6 ; 
           [0022]      FIG. 9  is a schematic view, similar to that of  FIG. 7 , of part of an inventive dampening unit according to a third exemplary embodiment of the invention; 
           [0023]      FIG. 10  is a detail of the part shown in  FIG. 9 ; 
           [0024]      FIG. 11  is a schematic top view of part of an inventive dampening unit according to a fourth exemplary embodiment of the invention in the area of a dampening solution metering device and of a dampening roller arranged directly downstream thereof; 
           [0025]      FIG. 12  is a side view of the part shown in  FIG. 11 ; 
           [0026]      FIG. 13  is a perspective side view of an alternative to the part shown in  FIG. 12 ; 
           [0027]      FIG. 14  is an edge section of an inventive dampening unit in a first state, and 
           [0028]      FIG. 15  is the edge section of  FIG. 14  in a second state. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIG. 1  is the basic design of a printing couple  20  of a printing unit of a web-fed rotary printing press in highly schematic fashion, where the printing couple  20  comprises a form cylinder  21 , a transfer cylinder  22 , an inking couple  23 , and a dampening unit  24 . On the form cylinder  21  of the printing couple  20  shown in  FIG. 1 , several printing forms  25  are arranged. The inking couple  23  is used to apply printing ink to the printing forms  20  arranged on the form cylinder  21  and the dampening unit  24  is used to apply dampening solution to printing form  25 . Only the ink form rollers  26  of the inking couple  23  are shown; these are the rollers which roll on the form cylinder  21 . With the help of the transfer cylinder  22 , over which at least one blanket has been pulled, the ink applied to the printing forms  25  is applied to a substrate  27  to be printed, where, for this purpose, an impression cylinder (not shown) cooperates with the transfer cylinder  22 . 
         [0030]    The dampening unit  24  has a dampening solution metering device  28 , which comprises several metering units (not shown in  FIG. 1 ). With the help of the metering units of the dampening solution metering device  28 , dampening solution is applied to a dampening roller  29  of a dampening roller train  30 . In the exemplary embodiment shown here, the dampening roller train  30  comprises a total of three dampening rollers, namely, the dampening roller  29  directly downstream of the dampening solution metering device  28 , a dampening roller  31  rolling on this dampening roller  29 , and a dampening form roller  32 , which rolls on the form cylinder  21  and thus ultimately applies the dampening solution to the printing forms  25  arranged on the form cylinder  21 . 
         [0031]      FIGS. 2 and 3  show the form cylinder  21  of a printing couple  20  in isolation, where four relatively wide printing forms  25  are arranged axially next to each other on the form cylinder  21 . According to  FIG. 3 , four relatively narrow printing forms  25  are arranged next to each other on the form cylinder  21  in the axial direction of the cylinder. It can be seen from a comparison of  FIG. 2  with  FIG. 3  that the width of the substrate  27  which is printed changes as a function of the width of the printing forms  25 . In the following, it will be assumed that each of the printing forms  25  serves for the printing of one page on the substrate  27  in question. 
         [0032]    To ensure optimum print quality, dampening solution is applied by a dampening unit  24  of a printing couple  20  to the printing forms  25  positioned on the form cylinder  21  of the printing couple  20 . This is done according to one embodiment of the invention in such a way that the dampening solution application is adapted to the width of the substrate  27  which will be printed or to the width of the pages to be printed on the substrate  27 . For this purpose, the dampening units described below in greater detail with reference to  FIGS. 4-15 . 
         [0033]      FIGS. 4 and 5  show schematic diagrams of part of an inventive dampening unit according to a first exemplary embodiment of the invention in the area of a dampening solution metering device  28   a  and a dampening roller  29   a  located directly downstream of the dampening solution metering device  28   a . In the exemplary embodiment of  FIGS. 4 and 5 , the dampening solution metering device  28   a  comprises several metering units  33  and  34  for dampening solution. All of the metering units  33  and  34  are designed to be stationary with respect to the dampening unit roller  29   a  located directly downstream of the dampening solution metering device  28   a . To adapt the dampening solution application to the printing width and/or to the widths of the pages to be printed on the substrate, the metering units  33  and  34  of the dampening solution metering device  28   a  are individually controllable such that, depending on the substrate width and/or the width of the pages, a first subset of metering units is active and a second subset of metering units is inactive. 
         [0034]    In the exemplary embodiment of  FIGS. 4 and 5 , the metering units form two groups, namely, a first group of metering units  33  and a second group of metering units  34 . Each of these two groups of metering units is adapted to a different substrate width and thus to a different page width. Within each group, the metering units  33  and  34  in question are arranged next to each other in the axial direction. As can be seen in  FIG. 5 , in this exemplary embodiment the metering units  33  and  34  of the different groups are arranged so that one group is above the other, namely, on a circular arc, so that all metering units  33  and  34  are the same distance away from the dampening unit roller  29   a.    
         [0035]    In the exemplary embodiment of  FIGS. 4 and 5  shown here, the metering units  33  are used to apply dampening solution when, on the form cylinder  21  according to  FIG. 3 , relatively narrow printing plates with relatively narrow pages are arranged. When, however, relatively wide printing plates for relatively wide pages are arranged on the form cylinder  21 , the dampening solution is applied by means of the metering units  34  of the dampening solution metering device  28   a.    
         [0036]    In the exemplary embodiment of  FIGS. 4 and 5 , the metering units  33  and  34  are designed as nozzle units, where two nozzle units are provided per page width to be printed. With the help of these nozzle units, dampening solution can be sprayed discontinuously onto the dampening roller  29   a.    
         [0037]      FIGS. 6-8  show schematic diagrams of part of a dampening unit according to a second embodiment of the invention.  FIGS. 6 and 7  show a dampening solution metering device  28   b  and a dampening roller  29   b  located directly downline from the dampening solution metering device  28   b . In the embodiment of  FIGS. 6-8 , the dampening solution metering device  28   b  has several metering units  35  for dampening solution. At least one of these metering units  35  and preferably all of the metering units  35  are designed to be movable relative to the dampening roller  29   b  in the axial direction thereof. 
         [0038]    For this purpose, the metering units  35  are supported movably on a guide rail  36 . To adapt the dampening solution application to the substrate width or to the page width, all of the movable metering units  35  are controllable individually in such a way that at least one of the movable metering units  35  changes its position relative to the dampening unit roller  29   b  in the axial direction thereof when there is a change in the substrate width or in the page width. Thus, in  FIG. 6 , displacements of the metering units  35  in the axial direction of the dampening unit roller  29   b  are shown by the arrows  37 , as a result of which the dampening unit is adapted to decreasing page widths or to decreasing substrate width. 
         [0039]    In the embodiment of  FIGS. 6-8 , a separate drive  38  is assigned to each metering unit  35  of the dampening solution metering device  28   b , so that each of the metering units  35  can be moved by its own motor along the guide rail  36 . For this purpose the drive  38  works together with a drive pinion  39 . 
         [0040]    In contrast to the exemplary embodiment of  FIGS. 6-8 , it is also possible according to a third exemplary embodiment of the present invention according to  FIGS. 9 and 10  to assign a common drive to several, preferably all, movable metering units  40  of a dampening solution metering device  28   c  in order to move the metering units  40  in the axial direction of the dampening roller  29   c.    
         [0041]    The drive (not shown in  FIGS. 9 and 10 ) then preferably drives a threaded rod  41 , where the threaded rod  41  cooperates with the appropriately threaded carriers  42  of the metering units  40 . Preferably the threaded rod  41  comprises individual threaded rod sections—individual, that is, with respect to the direction of the thread and/or its pitch—for at least some of the metering units  40 , preferably for all of the units. The metering units  40  are supported on these individual sections by the carriers  42  comprising the corresponding counterthread. By changing or adapting the direction of the thread, the metering units  40  can be made to travel in different directions. Through the use of threads with different pitches, the same rotation of the threaded rod  41  for actuating the metering units  40  can produce different translational adjusting movements of the metering units  40 . 
         [0042]    In the exemplary embodiments of  FIGS. 6-10 , the metering units are again designed as spray units. Because, in the case of dampening units with spray units, the ratio of the overlap of the various spray cones to their distance from the dampening roller located directly downstream of the dampening solution metering device is important, a radial component of the adjusting movement can be superimposed on the axial displacement of the metering units. 
         [0043]    In the exemplary embodiments of  FIGS. 1-10 , spray units are used as metering units, by means of which, as already explained, dampening solution is sprayed preferably discontinuously onto the dampening roller located directly downstream of the dampening solution metering device. 
         [0044]    In contrast,  FIGS. 11-13  show exemplary embodiments of the present invention in which the metering units of the dampening solution metering devices in question are designed as whirlers, by means of which dampening solution is flung off continuously by centrifugal force and thus applied to the dampening roller located directly downstream of the dampening solution metering device in question. 
         [0045]      FIGS. 11 and 12  show part of an inventive dampening unit according to a fourth embodiment of the present invention, again in the area of a dampening solution metering device  28   d  and a dampening roller  29   d  located directly downstream of the dampening solution metering device  28   d . The dampening solution metering device  28   d  again has several metering units  43 , where each of the metering units  43  is supported on a threaded rod  45  by way of a carrier  44 . A drive  46 , which drives the threaded rod  45  and thus shifts all of the metering units  43  of the dampening solution metering device  28   b  jointly, is assigned to the threaded rod  45 . To this extent the exemplary embodiment of  FIGS. 11 and 12  is the same as that of  FIGS. 9  an  10 , so that with respect to these details reference can be made to the explanation given above. 
         [0046]    In the exemplary embodiment of  FIGS. 11 and 12 , the metering units  43  are designed as whirlers, where all of the metering units  43  comprise a common rotor  56 , by means of which dampening solution can be flung toward the dampening unit roller  29   d . Each metering unit  43  has a shutter  47 , by means of which the quantity of dampening solution can be adjusted.  FIG. 12  shows a shutter  47  in two different positions, namely, in a closed position, in solid line, and in an open position, in dotted line, where, when the shutter  47  is open, the dampening solution is flung onto the dampening unit roller  29   d  in the form of a cone  48 . A drive  49  is assigned to each metering unit  43  to open and to close the shutter  47 . Preferably two metering units  43 , designed as whirlers, work together per page width, where the shutters  47  of the cooperating metering units  43  overlap. 
         [0047]    To adapt the dampening solution metering device  28   d  to a change in page width or to a change in substrate width, the metering units  43  cooperating with each other for each page width and can be moved relative to each other, where for this purpose at least one of the two cooperating metering units  43  or possibly each of them can be moved in the axial direction of the dampening unit roller  29   d.    
         [0048]      FIG. 13  shows a metering unit  50  representing an alternative to the metering unit  43  shown in  FIG. 12 . This alternative unit is again designed as a whirler. In the case of the metering unit  43  of  FIG. 12 , the drive  49  for actuating the shutter  47  can be moved together with the metering unit  43 . In the case of the metering unit  50  of  FIG. 13 , however, a drive  51 , which serves to actuate the shutter  47 , is stationary, where the drive  51  is connected to the shutter  47  to be actuated by a flexible shaft  52  and a coupling or clutch  53 . As a result, axial compensation can be achieved between the stationary drive  51  and the shutter  47 , which can shift position axially together with the metering unit  50 . 
         [0049]      FIGS. 14 and 15  show part of the drive unit of the exemplary embodiment of  FIGS. 9 and 10  in the area of the edge of the corresponding dampening solution metering device  28   c  for the purpose of making it clear that the edge sections of the dampening solution metering device adjacent in the axial direction to the outer metering units  40  can be at least partially blocked off. As a result, it can be guaranteed that no dampening solution or only a reduced amount of dampening solution will arrive on the form cylinder in question to the left and/or to the right of the substrate to be printed. So that this blocking in the edge areas can be adapted to different substrate widths or page widths, it must be designed to be movable. 
         [0050]    Thus  FIGS. 14 and 15  show an edge blocker  54  of the dampening solution metering device  28   c . It is designed in telescoping fashion as shown in  FIGS. 14 and 15 . In the exemplary embodiment shown, the telescope-like edge blocker  54  has three segments, which can shift their positions relative to each other. 
         [0051]    One of the segments is stationary, whereas the other two segments are movable. By way of a carrier  55 , one of the segments of the telescoping edge blocker  54  is supported on the threaded rod  21 , where this carrier  55  has a counterthread corresponding to the threaded rod  41 . The use of a telescoping edge blocker  54  is advantageous for space reasons. It is also possible, however, to use a roll-like blocker. 
         [0052]    The present invention can be applied in all cases in which a dampening unit must be adapted to changes in substrate widths or to changes in page widths. When there is a change in the width of a substrate to be printed, the corresponding printing couple of the printing press can run the substrate either the cylinder center or flush with one side of the machine. 
         [0053]    All of the motorized adjustments of the dampening units can be conducted automatically on the basis of presettings stored in the printing press. 
         [0054]    Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.