Abstract:
In order to transfer an image-type coating from a carrier film to a printed sheet, an image-type adhesive is applied to the printed sheet. In a film transfer module ( 2 ), the carrier film comprising the image-type coating is rolled over the printed sheet using contact pressure such that the coating adheres to the adhesive sections, thus forming an image. In order to improve the function, simplify the device and increase flexibility, a modular holder for film rolls of the transfer foil ( 5 ) is provided, allowing simplified handling.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is the national phase of PCT/EP2007/010940, filed Dec. 13, 2007, which claims the benefit of German Patent Application No. 102006060243.9, filed Dec. 20, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to printing machines, and more particularly, to printing machines which include a station for transferring imaging layers from a carrier film onto sheets being processed through the printing machine. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to produce metallic layers on sheets by means of a film transfer method. For example, EP 0 569 520 B 1 discloses a printing material and a printing device that utilizes this material. This publication describes a sheet-processing machine that includes a feeder and a delivery unit, wherein printing units and a film transfer module are arranged between these two assemblies. An adhesive pattern is applied in at least one of the printing units by means of a flatbed printing method. This adhesive pattern is applied in a cold-printing process. The film transfer module arranged downstream of the printing unit includes an impression cylinder and a transfer cylinder and is provided with a film guide. The film guide is designed in such a way that a film strip or transfer film is guided from a film supply reel through a transfer nip of the film transfer module between the impression cylinder and the transfer cylinder. The film strip is wound up once again on the outlet side after it emerges from the film transfer module. The transfer film has a carrier layer onto which imaging layers such as metallic layers, for example, of aluminum are applied. During the transport of sheets through the printing unit, each sheet is provided with an adhesive pattern. Subsequently, the sheet is guided through the film transfer module, wherein the sheet lying on the impression cylinder is brought into contact with the film material by means of the transfer cylinder. During this process, the metallic layer adheres to the regions of the sheet that are provided with adhesive. After transport of the sheet through the film transfer module, the metallic layer adheres only to the region of the patterns provided with adhesive. Thus, the metallic layer is removed from the carrier film in the region of the adhesive patterns and transfer film thereafter is re-wound. The sheet is thereupon delivered in the coated state. 
         [0004]    It is known to utilize film transfer modules of this type, for example, in printing units of printing machines. A disadvantage of known devices is that they cannot be flexibly utilized and the consumption of transfer film is expensive. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0005]    It is an object of the present invention to provide a printing machine that is operable for more reliably, economically, and precisely effecting the transfer of an imaging layer, such as a metallization layer, onto sheets being processed through the printing machine. 
         [0006]    Another object is to provide a printing machine of the foregoing type which simplifies manufacture, printing machine setup, and sheet handling. 
         [0007]    In carrying out the invention, one or more modular holders for reels of transfer film are provided for more efficient access and utilization. A strip of the transfer film is stored on one or more film reels within the module, and existing film reel can be used within the same module in order to change film reels by means of a film strip connecting device (receptacle modules). Two variations of modular receptacles for film reels that allow simple exchange of one of or more such reels are disclosed. 
         [0008]    According to a first embodiment, the receptacles may be provided in one module, wherein at least two shafts for accommodating film reels are arranged one on top of the other. One or more film reels may be arranged on each shaft. Drives may be provided for the shaft or shafts, and a strip tensioning unit may be provided for each holder for a film reel. This makes it possible to improve the set-up times in connection with a film transfer module. 
         [0009]    According to a second embodiment, the receptacles may be provided in two modules, wherein at least two shafts for accommodating film reels are arranged one on top of the other in each module. One or more film reels may be arranged on each shaft. Drives again may be provided for the shaft or shafts, and a strip tensioning unit may be provided for each holder for a film reel in at least one module. This makes it possible to further improve the set-up times in connection with a film transfer module because the exchange of film reels is significantly simplified. 
         [0010]    Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagrammatic depiction of an illustrative printing machine having a film transfer device; 
           [0012]      FIG. 2  is a fragmentary side elevational view of a printing machine having a receptacle module in accordance with the invention for housing film transfer film; and 
           [0013]      FIG. 3  is an alternative embodiment of a receptacle modular arrangement for handling of transfer film for an image transfer device of the printing machine. 
       
    
    
       [0014]    While the invention is susceptible of various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention. 
       DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Referring now more particularly to  FIG. 1  of the drawings, there is shown an illustrative sheet processing machine, namely a printing machine, that includes at least two printing units. In a first step, a sheet to be coated is provided with an imaging adhesive pattern in the application unit  1 . A printing unit of an offset printing machine with inking and dampening units  11 , a printing plate on a plate cylinder  12 , an offset blanket or blanket cylinder  13 , and an impression cylinder  4  may be used for this purpose. 
         [0016]    In a second step, a transfer film  5  is guided through a transfer nip  6  together with the sheet and pressed against the sheet. A film transfer module  2  used for this purpose may consist of a printing unit, a varnishing module, a base unit or another type of processing station of a sheet-fed offset printing machine. 
         [0017]    The transfer nip  6  in the film transfer module  2  is formed by a transfer cylinder  3  and an impression cylinder  4 . The transfer cylinder  3  may correspond to an offset blanket or plate cylinder of a generally known offset printing unit or a varnishing module of a sheet-fed offset printing machine. A strip guide for the transfer film  5  is illustrated within the film transfer module  2 . The device may also be arranged within a printing unit in the form of an integrated film transfer module FA. 
         [0018]    In the basic arrangement shown in  FIG. 1 , the film transfer module  2  has a film supply reel  8  on a side of the sheet feeder. The film supply reel  8  has a rotary drive  7  operable under appropriate control for ensuring a continuous, controlled supply of the transfer film  5  to the film transfer module  2 . Furthermore, control equipment  14  such as deflection and tensioning rollers, pneumatically actuated control elements, directional baffles or the like are provided in the region of the film feeder and the film delivery unit. This makes it possible always to guide the strip of transfer film  5  without distortions and to maintain the tension of the film strip constant relative to the transfer cylinder  3 . 
         [0019]    The transfer film  5  can be guided around the transfer cylinder  3 , wherein the transfer film  5  can be advantageously supplied to and delivered from the transfer nip  6  from one side of the film transfer module  2  only as depicted in broken lines in  FIG. 1 . In addition, the transfer film  5  essentially may also be guided on the transfer cylinder  3  tangentially or be looped around said transfer cylinder by a small angle circumferentially in the transfer nip  6 . The transfer film  5  is fed to one side of the film transfer module and delivered to its opposite side. A film collecting reel  9  for winding used film material is illustrated on the outlet side of the printing unit. A controllable rotary drive  7  is also provided in this case. 
         [0020]    Supplementary dryers  16  further may be arranged in a film transfer module  2  or FA in order to pre-dry the adhesive on the substrate and/or to completely dry the finished coating. The coating quality can be monitored by means of an inspection device  17 . Furthermore, cleaning devices R are provided in the film transfer module  2  or FA in order to remove foreign matter that drops off the film strip of the transfer film  5  and may adhere to the cylinders. 
         [0021]    In accordance with the invention, devices for the form of modular holders are provided for accommodating film reels.  FIG. 2  shows an embodiment of a device that includes a single receptacle module  19  for film reels  20 ,  21  attached or associated with the film transfer module  2  or FA. The receptacle module  19  is provided with two shafts  22 ,  23  for holding respective film reels  20 ,  21 . One or more film reels  20 ,  21  can be held on each shaft  22 ,  23  in accordance with processing tracks that lie parallel to one another relative to the transport direction of the sheets to be coated. 
         [0022]    The transfer film  5  is fed to the transfer nip  6  from one or more film reels  20  that are held on the lower shaft  22  on the right side of the film transfer module  2  or FA. The used transfer film  5  is returned from the transfer nip  6  to one or more film reels  21  held on the upper shaft  23  parallel to the film transfer module  2  or FA. All shafts  22 ,  23  may be provided with rotary drives in order to drive or decelerate the film reels  20 ,  21 . 
         [0023]    A strip tensioning unit  24  is arranged beneath the lower shaft  22  or the film reel  20  held thereon. The strip tensioning unit  24  may be in the form of a retractable module having several guide rollers  25  that can be adjusted in accordance with the required strip tension of the film strip relative to its strip path. The adjustment may be appropriately controllable as a function of the strip tension. Depending on the number of film reels  20  that are arranged on the shaft  22  in accordance with the processing tracks, several strip tensioning units  24  may also be arranged parallel to one another in the form of exchangeable modules. Consequently, this arrangement makes it possible to respectively operate with one film strip of the format width or with several film strips of a partial format width. 
         [0024]      FIG. 3  shows an alternative embodiment with a first receptacle module  26  for film reels  27 ,  28 , similar to the module  19  in  FIG. 2 , and a second receptacle module  26  for film reels  30 ,  31 . The first receptacle module  26  is coupled or attached to the film transfer module  2  or FA, and the second receptacle module  29  is coupled or attached to a printing or processing unit  32  of the sheet processing machine that is arranged downstream thereof. Each of the receptacle modules  26 ,  29  is respectively provided with two shafts  33 ,  34  and  35 ,  36 , respectively, for holding film reels  27 ,  28  and  30 ,  31 . One or more film reels  27 ,  28  and  30 ,  31  again may be held on each of the shafts  33 ,  34  and  35 ,  36  corresponding to the processing tracks on the sheet to be printed that need to be supplied. An again, each of the shafts  33 ,  34  and  35 ,  36  may be provided with a rotary drive for driving or decelerating the film reels  27 ,  28  and  30 ,  31 . 
         [0025]    The transfer film  5  is fed to the transfer nip  6  from one or more film reels  27 ,  28  of the first receptacle module  26 . In this case, the transfer film  5  can be fed to the transfer nip  6  for each processing track from either film reels  27  held on the lower shaft  33  or from film reels  28  held the upper shaft  34  on the right side of the film transfer module  2  or FA. The used transfer film  5  is returned from the transfer nip  6  to the second receptacle module  29  and its film reels  30 ,  31  held on upper and lower shafts  35 ,  36  parallel to the film transfer module  2  or FA. 
         [0026]    In the first receptacle module  26 , a strip tensioning unit  37  is arranged underneath the lower shaft  33  or the film reels  27  held thereon. The strip tensioning unit  37  again may be in the form of a retractable module having several guiding rollers that can be adjusted in accordance with the required strip tension of the film strip relative to its strip path, the adjustment of which may be appropriately controllable as a function of the strip tension. 
         [0027]    Depending on the number of film reels  27 ,  28  that are arranged on the shafts  33 ,  34  in accordance with the required processing tracks, several strip tensioning units  37  may also be arranged parallel to one another in the form of exchangeable modules. In addition, one or more corresponding strip tensioning unit(s)  38  is/are assigned to the upper shaft  34  or the film reels  28  held thereon. 
         [0028]    In the latter-described arrangement, it is also possible to respectively operate with one film strip of the format width or with several film strips or transfer films that are arranged in accordance with the required processing tracks and respectively have a partial format width. 
         [0029]    The arrangement also allows for a quick-change operating mode concept in which several film reels can be used per processing track. Furthermore, a device is created within the printing machine that can be fitted with film reels and operated analogously to a reel changer. For this purpose, a back up supply reel  28  for transfer film  5  may be provided on a free shaft  34  in the receptacle module  26  as depicted in  FIG. 3 , while the active film reel  27  is processed. The film strip from the back up reel  28  can be glued to the active film reel  27  at a standstill when or shortly before the transfer film  5  is completely used up. This may be effected manually or semi-automatically with the aid of auxiliary means. Consequently, the new transfer film of the new film reel  28  can be directly pulled into the film transfer module  2  by means of the transfer film being currently processed. 
         [0030]    This also makes it possible to automate the foregoing system. For this purpose, a sufficient quantity of transfer film  7  may be stored in a magazine, e.g., in connection with a strip tensioning unit  37  or  38  for the transfer film being unwound from the active film reel  27 . The active film from the reel  27  can then be glued to the new film reel  28  to be used. An appropriate acceleration of the next film reel  28  to be used, if applicable, up to the machine speed simplifies the exchange between old and new film reel  27  and  28  to such a degree that a quasi-continuous reel change takes place. This process can also be fully automated, as is known in automatic reel changers of web-processing printing machines. In this case, the conventional arrangement of the film transfer module in the form of two printing towers according to  FIG. 1  is preserved. 
         [0031]    It would also be possible to effect a double arrangement of the film reels  30 ,  31  that wind up the film strip. If an automatic reel change from a full wind-up reel to an empty wind-up reel also is required, the processes for set-up and take-down can also be carried out by the support personnel during idle times or with minimal or even no production interruptions. The arrangement can be additionally improved if the shafts  22  or  33 ,  33  and  34  or  35  and  36  of the receptacle modules  19  or  26  and  29  are loaded and unloaded on their face sides, e.g., from the rear side of the printing machine. 
         [0032]    The strip tensioning units  37 ,  38  illustrated in  FIGS. 2 and 3  extend over the entire width of the device. This makes it possible to accommodate any arrangement and width of the film strips or partial film strips during the film transfer. Consequently, strip handling and guiding can be effected in a completely variable fashion with respect to the position and width of the partial film strips and their arrangement relative to the position of the processing tracks on the printing substrate. 
         [0033]    In order to additionally improve the arrangement, a device may be provided for detecting the gluing point in the film strip to the film guide. A corresponding sensor arrangement is positioned between the film being unwound in the receptacle module  19  or  26  and the feed of the transfer film  5  to the transfer nip  6  in the film transfer module  2 . The detection of the gluing point makes it possible to detect the sheet or sheets that contain the gluing point or are situated upstream or downstream of the gluing point, as well as to sort out and identify these sheets in the delivery stack of the printing machine with the aid of corresponding auxiliary means. For this purpose, the corresponding distances traveled by the sheet and the transfer film can be calculated with the aid of a computer. Alternatively, the gluing point can be marked by means of an RFID-transponder or a magnetic strip and detected with sensors. In this context, it is also possible to transfer the marking element onto the sheets even in case there are several film strips. Different copies on the sheet can then be detected as faulty in an additional processing station, such that copies with film gluing points can be reliably sorted out. 
         [0034]    In addition, the used film strip can be transported away downstream of the transfer nip by means of turning bars, such that it is guided laterally out of the printing machine. In this case, the film strip can be wound up above auxiliary assemblies arranged beside the printing machine. The used film strip could also be shredded and removed by suction at this location. 
         [0035]    From the foregoing, it can be seen that the described device makes it possible to operate with one film reel of the format width or several narrower film reels over the format width in accordance with the processing tracks required on the sheet to be printed. The processing may take place in a synchronized or non-synchronized fashion. 
         [0036]    A film severing device, if applicable, with a film capture device may be provided with the film transfer module in the vicinity of the reel being unwound in order to detect a torn film. The torn film detection is realized with the aid of the strip tension measurement or control and/or a strip monitoring sensor arrangement. 
       LIST OF REFERENCE SYMBOLS 
       [0037]      1  Application unit 
         [0038]      2  Film transfer module 
         [0039]      3  Transfer cylinder 
         [0040]      4  Impression cylinder 
         [0041]      5  Transfer film/film strip 
         [0042]      6  Transfer nip 
         [0043]      7  Reel drive 
         [0044]      8  Film supply reel 
         [0045]      9  Film collecting reel 
         [0046]      10  Press covering 
         [0047]      11  Inking/dampening unit 
         [0048]      12  Plate cylinder 
         [0049]      13  Offset blanket cylinder 
         [0050]      14  Guiding device 
         [0051]      15  Protective cover 
         [0052]      16  UV-dryer 
         [0053]      17  Monitoring system 
         [0054]      18  Dancer roll 
         [0055]      19  Receptacle module 
         [0056]      20  Film reel (wind-up) 
         [0057]      21  Film reel 
         [0058]      22  Shaft 
         [0059]      23  Shaft 
         [0060]      24  Strip tensioning module 
         [0061]      25  Guide roller 
         [0062]      26  Receptacle module 
         [0063]      27  Film reel 
         [0064]      28  Film reel 
         [0065]      29  Receptacle module 
         [0066]      30  Film reel (wind-up) 
         [0067]      31  Film reel (wind-up) 
         [0068]      32  Printing or processing unit 
         [0069]      33  Shaft 
         [0070]      34  Shaft 
         [0071]      35  Shaft 
         [0072]      36  Shaft 
         [0073]      37  Strip tensioning unit 
         [0074]      38  Strip tensioning unit 
         [0075]    FA Film transfer module