Abstract:
A dry cleaning apparatus, assembly and method provides for a dry flexographic plate cleaner apparatus that is configured as a unitary subassembly to be used within a printing press assembly. The cleaner apparatus and subassembly comprise a plurality of motorized drives such that, among other things, a cleaning roller can be moved towards and away from the rotating printing plate so as to achieve optimum spacing. This also allows the press operator to make adjustments to the cleaner apparatus and subassembly without having to stop the printing press assembly. The apparatus and subassembly is further removable from the printing press assembly as may be desired or required for service. Additionally, the apparatus, assembly and method of the present invention also provides for use of at least one controller for electronically controlling the apparatus in accordance with the method and implementing optimized cleaning capabilities and functionalities.

Description:
This Application claims the benefit of U.S. Provisional Application No. 61/884,040, filed Sep. 28, 2013 and U.S. Provisional Application No. 62/025,160 filed Jul. 16, 2014. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to flexographic printing machines and systems. More specifically, the present invention relates to a dry cleaning apparatus and assembly that is used for cleaning the outer surface of a flexographic printing plate as the plate rotates on a plate cylinder. It also relates to a method that is drawn to the use of such apparatus and assembly. It also relates to providing one or more supplemental sub-systems and methods for optimizing one or more cleaning functionalities used with an interface to at least one controller that is incorporated into the apparatus and assembly of the present invention. 
     BACKGROUND OF THE INVENTION 
     In the art of flexographic printing, a plate is carried on a rotating cylinder. The plate carries a print medium that is then applied to a surface. During the printing process, certain debris, such as dust, paper fibers and other residue, is unavoidably deposited onto the plate. This type of debris can result in poor print quality and needs to be removed from the plate to maintain optimum print quality. It is also desirable to remove such debris without having to shut down the printing press because doing so adversely impacts productivity. That is, it is known in the prior art that shutting down the press to manually wipe debris from the printing plate accomplishes the intended purpose, but at the expense of lowering print production. Other methods are known in the art that use a more mechanized process for cleaning a printing plate, but do so by degrading the surface of the printing plate by repeated cleanings and imprecise placement of a cleaning device relative to the printing plate. These mechanized processes of the prior art also result in a degradation of print quality due to the degradation of the surface of the printing plate. A “dry” system is preferred in that it minimizes color deviation in the ink and produces no waste water, which water then needs to be properly disposed of. 
     Accordingly, it is an object of the present invention to provide An apparatus, assembly and method for dry cleaning of a flexographic printing plate, the plate being carried on a plate cylinder, as the plate rotates on a print cylinder and without stopping the printing press whereby minimal degradation of the printing plate surface is realized. It is another object to provide such an apparatus, assembly and method whereby the apparatus is adjustable in several axes relative to the rotating plate so as to optimize cleaning. It is still another object to provide such an apparatus, assembly and method whereby the apparatus and assembly can be easily removed from the printing press for service and maintenance when necessary. It is yet another object of the present invention to provide such an apparatus, assembly and method that incorporates a number of added performance characteristics that are intended to optimize cleaning capabilities when the apparatus, assembly and method is used as intended. 
     SUMMARY OF THE INVENTION 
     The dry cleaning apparatus, assembly and method of the present invention has obtained these objects and others. It provides for a dry flexographic plate cleaner apparatus that is configured as a unitary subassembly to be used within a printing press assembly. The cleaner apparatus and subassembly comprise a plurality of motorized drives such that, among other things, a cleaning head can be moved towards and away from the rotating printing plate so as to achieve optimum spacing. This also allows the press operator to make adjustments to the cleaner apparatus and subassembly without having to stop the printing press assembly, which avoids press downtime and maintains desired production speeds. The cleaner apparatus and subassembly is further removable from the printing press assembly as may be desired or required for service. Additionally, the apparatus, assembly and method of the present invention, which is used for dry cleaning a printing plate that is carried on a print cylinder, also provides for use of at least one controller for electronically controlling the apparatus in accordance with the method and implementing optimized cleaning capabilities and functionalities. 
     The foregoing and other features of the dry cleaning apparatus, assembly and method of the present invention will be apparent from the detailed description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one preferred embodiment of the dry cleaning apparatus and subassembly that is constructed in accordance with the present invention. 
         FIG. 2  is another perspective view of the dry cleaning apparatus and subassembly shown in  FIG. 1 . 
         FIG. 3  is a side elevation view of the apparatus and subassembly shown in  FIGS. 1 and 2 . 
         FIG. 4  is a partially sectioned side elevation view of the apparatus and subassembly from the side opposite that shown in  FIG. 3 . 
         FIG. 5  is a perspective view of the dry cleaning apparatus and subassembly as used within a printing press assembly, and showing the apparatus and subassembly in the “parked” position relative to the rotating printing plate of the printing press assembly. 
         FIG. 6  is a perspective view similar to that of  FIG. 5  but showing the apparatus and subassembly in the “active” position relative to the rotating printing plate of the printing press assembly. 
         FIG. 7  is a side elevational view of a portion of the dry cleaning subassembly illustrated in  FIG. 5 . 
         FIG. 8  is a perspective view similar to that shown in  FIG. 7 . 
         FIG. 9  is a perspective view of the dry cleaning apparatus of shown from the side opposite that shown in  FIG. 7 . 
         FIG. 10  is a side elevational view of a portion of the dry cleaning subassembly illustrated in  FIG. 7 , but shown from the opposite side. 
         FIG. 11  is a graphical diagram relative to the functionality of the assembly and apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawing views in detail, wherein like numbered elements refer to like elements throughout the drawing,  FIGS. 1 through 4  illustrate a preferred and representative embodiment of the printing plate cleaner structure (also alternatively and interchangeably referred to in this detailed description as a “plate cleaner,” a “plate cleaner apparatus” or a “plate cleaner subassembly”), generally identified  10 , of a dry cleaning apparatus and subassembly that is fabricated in accordance with the present invention. 
     As shown, the plate cleaner  10  comprises a frame having a first frame member  12  and a second frame member  14 . In the preferred embodiment, the plate cleaner  10  comprises three motors—a linear actuator motor  52 , a cloth rewind motor  16  and an impression or “tilt” motor  18 . It is to be understood that such motors may be one motor, or any combination of motors, from a group consisting of electric motors, hydraulic motors, pneumatic motors and the like, the type of motors used not being a limitation of the present invention. 
     The frame  12 ,  14  of the plate cleaner  10  also comprises a roller  20  and two spindles  30 ,  40 . See  FIG. 4 . In the preferred embodiment, the frame of the plate cleaner  10  is disposed above the printing plate cylinder  60  of a printing press assembly, generally identified  100 . See  FIGS. 5 and 6 . In this embodiment, the roller  20  is disposed toward the bottom of the frame  12 ,  14  and the roller  20  has an axis that is parallel to that of the printing plate cylinder  30 . The roller  20  is also that structure of the plate cleaner  10  over which a portion of dry cleaning material  22  is pulled, the dry cleaning material  22  being fed from a web of such material that is disposed within the frame  12 ,  14  of the plate cleaner  10 . It is also within the scope of the present invention to provide a version of plate cleaner  10  having a roller  20  that adjusts impression using an eccentric cam on its roller shaft (not shown). This version allows for a smaller footprint and provides more versatility to the functionality of the plate cleaner  10 . 
     In the preferred embodiment, one of the spindles is an “unwind” spindle  40  that carries the web of unsoiled dry cleaning material, such as a woven or non-woven polyester, or any other absorbent cloth or cloth-like material. The other spindle is a “rewind” spindle  30  that pulls the web of dry cleaning material from the unwind spindle  40 , then about a portion of outer surface of the roller  20  and back to the rewind spindle  30 . At the point of rewind, the dry cleaning material  22  is soiled with printing debris and ink, as described above. 
     However, it is to be understood that the exact placement of the rewind and unwind spindles  30 ,  40 , respectively, relative to the plate cleaner subassembly  10  of the present invention is not a limitation of the present invention. That is, different configurations of the spindles are available depending on the specific application and use to which the plate cleaner  10  of the present invention is desired or required. However, the functionality of the pulling of the dry cleaning material  22  from an unwind spindle  40 , across a portion of the roller  20  and back to a rewind spindle  30  is required regardless of placement of those structures within the plate cleaner  10 . It is also intended that the axes of the roller  20  and the spindles  30 ,  40  be parallel with the longitudinal axis of the print plate cylinder  60 , although the spindles  30 ,  40  could be used with other structures to accomplish feeding or take-up of the unsoiled or soiled dry cleaning material, respectively. 
     The linear actuator motor  52  provides a means for moving the plate cleaner  10  longitudinally along a track subassembly  50  that is also parallel to the longitudinal axis of the print plate cylinder  60 . Again, see  FIGS. 5 and 6 . The second frame portion  14  is used to move along the track subassembly  50 . The cloth roller motor  16  pulls a web of dry cleaning material from the unwind spindle  40  to the rewind spindle  30  via worm gears, although other drive mechanisms could be used. The impression or “tilt” motor allows the roller of the plate cleaner  10  to move toward and away from the surface  62  of a printing plate that is attached to the print cylinder  60 . This last structure is significant in that it provides functionality such that relatively tight or precise control of the pressure that the plate cleaner roller places on the printing plate surface  62  as the printing plate and the print cylinder rotate is attained. This allows the cleaning roller  20  and the material  22  to be moved closer to or farther from the surface  62  of the printing plate for optimized spacing and cleaning of that surface thereby placing more or less pressure on the printing plate, respectively. This also allows the operator to make position and pressure adjustments between the plate cleaner  10  and the print plate surface  62  without the need to stop the printing press  100  or the printing process. 
     In the preferred embodiment, the roller  20  is a urethane foam covered roller. This allows for further tactile adjustment of the plate cleaner  10  to the surface of the print plate because the roller  20  has some amount of material yield or “give” to it. Also in the plate cleaner  10  of the preferred embodiment, a measuring device  11  is used to determine the distance between the roller  20 , and the web  22  passing over it, and the printing plate surface  62  to measure optimum spacing. Such measuring device  11  can be electrical, mechanical, electromechanical or photoelectric, among others. See  FIGS. 9-11 . 
     In the plate cleaner  10  of the preferred embodiment, a mounting means and a quick disconnect means is provided such that the plate cleaner  10  can be removed from the printing press assembly  100  for service as may be desired or required. 
     Also in accordance with the preferred embodiment, the present invention provides an electronic controller  70  that utilizes a controller network interface and an electronic control unit to monitor and control the cleaner directly or in accordance with a preprogrammed scheme. The electronic controller  70  uses programmable software to determine operational parameters and institute electronic commands to the electronic control unit in a pre-determined response operational framework. When the controller  70  is enabled, it monitors certain operational parameters of the plate cleaner  10 . In the controller  70  of the present invention, the operational parameters are configurable, allowing the setup to be optimized for a particular method of operation, regardless of the specific application that the plate cleaner is used for, and is programmable to make adjustments accordingly. See  FIG. 11 . 
     In accordance with the preferred embodiment, the controller  70  of the present invention also comprises a number of automated and enhanced cleaning functionalities that may or may not be included with the base apparatus, system and method of the present invention. Each functionality is intended to interface with the electronic controller  70  of the present invention to enhance overall operation and optimization of the apparatus, system and method of the present invention. 
     For example, one functionality comprises the incorporation of a feedback loop that interfaces with the controller  70  and allows the cleaning setup to be fully automated. More specifically, this functionality can include, among other things, the use of a laser to provide a method for assessing cleaning apparatus efficacy and optimization feedback  72 . Other technologies could also be used such as the incorporation of ultrasound for providing optimization feedback, strain gauges for measuring torque, among other modalities. It is to be understood that the feedback optimization as is disclosed herein is not limited to the specific embodiments discussed herein and the present invention is not so limited. 
     In addition to making the process fully automatic, another subassembly can be incorporated to “map” where the printing plate  62  is disposed on the plate cylinder  60  and then configure the cleaning program accordingly. Various other mapping technologies can be incorporated as well and the present invention is not limited in this regard. 
     Another desired functionality is to include certain testing that is performed to determine if certain images or colors require different cleaning programs. This type of information can be used in conjunction with the feedback functionalities and the electronic controller  70  mentioned above. This would be considered by these inventors to be “adaptive profiling”  74 . Most significantly, the combined functionality will be provided to optimize the cleaning process so that cleaning of the printing plates  62  is done in areas where cleaning is necessary and not done in areas where cleaning is not necessary, which minimizes the amount of time necessary to complete the cleaning cycle. The present invention is unique in its ability to clean specific areas of the printing plates  62  in this fashion. Again, the adaptive profiling technique disclosed herein is not limited to the specific disclosure discussed above, but could incorporate other technologies as well and the present invention is not so limited. The adaptive profiling technique can also be used to adapt to certain images and colors, each of which may require different cleaning programs. 
     Another performance optimization and enhancement feature can be to include the use of a camera sub-system (not shown), the camera sub-system can be coupled to the apparatus, system and method of the present invention. The camera sub-system similarly provides feedback information as to those specific areas of the printing plate  62  that require cleaning, similar to that which is described above. That is, information from the camera sub-system can be used to optimize the cleaning process by cleaning only those areas of the printing plate that need cleaning and then only as frequently as is necessary, all for optimization of the cleaning process. 
     Lastly, it has been found by these inventors that the apparatus, system and method of the present invention removes debris that can result in what are known to those skilled in the art as “hickeys” on the print sheet. Further, it has been found that the present invention also improves the printed image by maintaining a more consistent ink film on the printing plate  62 . These optimization techniques are novel and patentably different from prior art methods that have been used for simply cleaning the printing plate  62 .