Abstract:
An ink cooling system for printing presses is disclosed. The ink cooling system is arranged to cool ink at locations within a printing press at the locations in which the ink properties are most likely to be adversely impacted, and which locations are or may be physically remote from the centralized ink supply or ink tanks. The disclosed system thus counteracts localized heating that commonly occurs in printing presses, thus minimizing or eliminating printing problems caused by heated ink.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. provisional application Ser. No. 60/339,057, filed Oct. 30, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to printing presses and, more specifically, to a system for cooling ink and/or coatings on printing presses.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is known that the normal operation of a printing press produces heat. On many printing components, this heat may be the result of friction. For example, the anilox roll makes direct contact with the doctor blades in the chamber doctor blade system. Friction between the doctor blades and the anilox roll may cause one or more of these components to heat up. Further, friction between the anilox roll and other components, such as the plate cylinder, likewise may cause the anilox roll and other components to generate still additional heat. Still further heat is generated by plate rolls and other press components, such as, for example, dryers. Finally, additional heat may result from the ambient heat in the press room.  
           [0004]    According to normal thermodynamic processes, the generated heat is readily transferred to the ink used on the printing press. In some press components, such as the aforementioned chamber doctor blade system, a relatively small quantity of ink may be exposed to a relatively high and localized heat source. Furthermore, the chamber or the pan may function as a heat sink, providing another avenue for routing heat to the ink.  
           [0005]    As the ink heats up, various components of the ink may be lost, such as, by way of example rather than limitation, volatiles, solvents, amines, etc. Unfortunately, this heated and altered ink tends to have a detrimental effect on the overall quality of the printing operation. Additives and the labor or equipment required to correct the ink properties add additional expense. Accordingly, it may be desirable to cool the ink in order to prevent the negative impact on print quality. However, merely cooling the general ink supply is not sufficient to address the localized heating that occurs at some of the press components. The foregoing discussion may be equally applicable to coating systems which apply liquid coatings to a web or other substrate in a printing press. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is an elevational view of a six color flexographic common impression printing press;  
         [0007]    [0007]FIG. 2 is an elevational view of a wide web stack type flexographic printing press;  
         [0008]    [0008]FIG. 3 is an elevational view of a narrow web in-line flexographic printing press;  
         [0009]    [0009]FIG. 4 is a schematic representation of a flexographic ink train system for supplying ink to the chamber doctor blade system on a printing press and also employing a localized ink cooling system assembled in accordance with the teachings of the present invention;  
         [0010]    [0010]FIG. 5 is a fragmentary elevational view of a fountain roll for applying ink to an anilox roll and employing a single reverse angle doctor blade and also employing a localized ink cooling system assembled in accordance with the teachings of the present invention;  
         [0011]    [0011]FIG. 6 is an enlarged fragmentary view in perspective of an enclosed doctor blade system for applying ink to an anilox roll and also employing a localized ink cooling system assembled in accordance with the teachings of the present invention;  
         [0012]    [0012]FIG. 7 is a schematic illustration showing a system for supplying ink to an enclosed doctor blade system and also employing a localized ink cooling system assembled in accordance with the teachings of the present invention;  
         [0013]    [0013]FIG. 8 is an enlarged fragmentary elevational view of an enclosed doctor blade system and illustrating a plurality of coolant supply tubes running through a portion of the enclosed chamber;  
         [0014]    [0014]FIG. 9 is an enlarged fragmentary elevational view similar to FIG. 8 and illustrating a plurality of coolant supply tubes running around an external surface of the enclosed chamber;  
         [0015]    [0015]FIG. 10 is an enlarged fragmentary elevational view similar to FIGS. 8 and 9 and illustrating an electronic cooling device mounted on an external surface of the enclosed chamber;  
         [0016]    [0016]FIG. 11 is an enlarged fragmentary elevational view similar to FIG. 10 and illustrating an electronic cooling device mounted internally within the enclosed chamber;  
         [0017]    [0017]FIG. 12 is a perspective view of a doctor blade system incorporating an ink cooling system assembled in accordance with the teachings of yet another disclosed example of the present invention;  
         [0018]    [0018]FIG. 13 is an enlarged end view thereof;  
         [0019]    [0019]FIG. 14 is an exploded view thereof;  
         [0020]    [0020]FIG. 15 is a cross-sectional view taken along line  15 - 15  of FIG. 12 and incorporating a first type of coolant flow passages;  
         [0021]    [0021]FIG. 16 is a cross-sectional view similar to FIG. 15 but incorporating a second type of coolant flow passages;  
         [0022]    [0022]FIG. 17 is a schematic flow diagram illustrating the coolant flowing through the doctor blade system in a parallel flow arrangement;  
         [0023]    [0023]FIG. 18 is another schematic flow diagram illustrating the coolant flowing through the doctor blade system in a counter flow arrangement;  
         [0024]    [0024]FIG. 19 is yet another schematic flow diagram illustrating the coolant flowing through the doctor blade system in another flow arrangement; and  
         [0025]    [0025]FIG. 20 is a still further schematic flow diagram illustrating the coolant flowing through the doctor blade system in another counter flow arrangement employing only a single header;  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    The examples described herein are not intended to be exhaustive or to limit the scope of the invention to the precise form or forms disclosed. Rather, the following exemplary embodiments have been chosen and described in order to best explain the principles of the invention and to enable others skilled in the art to follow the teachings thereof.  
         [0027]    Referring now to FIG. 1 of the drawings, a six color flexographic common impression printing press of the type commonly known in the art is referred to by the reference numeral  20 . It will be understood that the teachings of the present invention may be equally applicable to other types of printing presses in addition to those presses specifically mentioned herein. The press  20  typically includes a plurality of printing stations, for example  20 - 1  through  20 - 6 , for applying ink to a web  22 . As would be known, each of the printing stations  20 - 1  through  20 - 6  includes a system for applying ink to an anilox roll, such as a doctor blade system (FIGS. 4 and 6 through  11 ), or a fountain pan system (FIG. 5), which are discussed in greater detail below. Each station  20 - 1  through  20 - 6 , as well as the press  20 , also include a plurality of other components, all of which may be conventional and would be known to those of skill in the art.  
         [0028]    Referring now to FIG. 2 of the drawings, a wide web stack type flexographic printing press of the type commonly known in the art is referred to by the reference numeral  24 . The press  24  typically includes a plurality of printing stations, for example  24 - 1  through  24 - 4 , for applying ink to the web  22 . As would be known, each of the printing stations  24 - 1  through  24 - 4  includes a system for applying ink to an anilox roll. Again, such a system may comprise a doctor blade system (FIGS. 4 and 6 through  11 ), or a fountain pan system (FIG. 5). Each station  24 - 1  through  24 - 4  as well as the press  24  includes a plurality of other components, all of which may be conventional and would be known to those of skill in the art.  
         [0029]    Referring now to FIG. 3 of the drawings, a narrow web in-line flexographic printing press of the type commonly known in the art is referred to by the reference numeral  26 . The press  26  typically includes a plurality of printing stations, for example  26 - 1  through  26 - 4 , for applying ink to the web  22 . As would be known, each of the printing stations  26 - 1  through  26 - 4  includes a system for applying ink to an anilox roll. Again, such a system may comprise a doctor blade system (FIGS. 4 and 6 through  11 ), or a fountain pan system (FIG. 5). Each station  26 - 1  through  26 - 4  as well as the press  26  includes a plurality of other components, all of which may be conventional and would be known to those of skill in the art. Again, the above-identified presses  20 ,  24  and  26  are mentioned herein for purposes of illustration only. The use of other types of presses may be contemplated. For the sake of convenience, the following discussion will refer only to the press  20 . It will be understood that the teachings described herein may be equally applicable to each of the aforementioned presses  20 ,  24 ,  26 , and to any flexographic, gravure, and/or offset lithographic presses. Further, it will be understood that the teachings described herein may be applicable to other systems and/or methods of applying inks, coatings, and/or other materials to a substrate.  
         [0030]    Referring now to FIGS. 4, 6 and  7 , a flexographic ink train system  28  is used to apply ink  30  to an anilox roll  32  on the press  20 , for subsequent application to a plate cylinder  34  (FIGS. 4 and 6). As outlined above, the system  28  may be equally applicable to any one of the presses  20 ,  24 ,  26  mentioned above. The system  28  includes an enclosed chamber doctor blade system  36 , an ink tank  38 , a pump  40 , a filter  42 , and a viscosity controller  44 . A plurality of lines  46 ,  48 ,  50 , and  52  are provided for routing to the ink  30  to and between the various components. The doctor blade system  36  includes a pair of doctor blades  54 ,  56  as would be known, and further includes a chamber  58  which contains a quantity of the ink  30 . The ink  30  is supplied to the doctor blade system  36  via the line  48 , and is returned through the line  50  to the ink tank  38  in a conventional manner.  
         [0031]    The system  28  is provided with an ink cooling system  60  assembled in accordance with the teachings of a first disclosed example of the present invention. The system  60  includes a refrigeration unit  62  and an exchange unit  64 . The exchange unit  64  is mounted to the chamber  58  so as to cool the ink  30  disposed within the chamber  58 . A supply line  66  routes a refrigerant (which may be any one of a number of commercially available refrigerants) or other coolant medium, such as chilled water, to the exchange unit  64 , and a return line  68  returns the refrigerant to the refrigeration unit  62 . The cooling operation carried out by the refrigeration unit  62  and the exchange unit  64  may be conventional using well known refrigeration/cooling principles. It will be understood that the refrigeration unit  62  will typically include a pump, a compressor, an expansion valve, etc., and other conventional components (not shown) as would be known. It will be understood that the aforementioned components may also be applied to a system for applying coatings to a web or other substrate in order to cool the coating material in a similar manner.  
         [0032]    Referring now to FIG. 5, a fountain roll system  70  for applying the ink  30  to the anilox roll  32  is shown. Also shown are a plate cylinder  72  and an impression cylinder  74 , which cooperate to apply the ink  30  to the web  22  in a conventional manner. The fountain roll system  70  includes an ink pan  76  and a fountain roll  78  which rotates in the ink pan  76  so as to pick up a quantity of the ink  30  contained therein for transfer to the anilox roll  32 . The fountain roll system  70  also includes one or more doctor blades, with a single reverse angle doctor blade  80  shown.  
         [0033]    The system  70  also includes the ink cooling system  60  similar to that outlined above. The exchange unit  64  is mounted to the ink pan  76  so as to cool the ink  30  disposed within the ink pan  76 . The supply line  66  and the return line  68  route the refrigerant between the exchange unit  64  and the refrigeration unit  62 . Again, the cooling operation carried out by the refrigeration unit  62  and the exchange unit  64  may be conventional using well known refrigeration/cooling principles.  
         [0034]    The exchange unit  64  may take a number of forms. For example, referring now to FIG. 8, the exchange unit  64  shown therein includes a plurality of cooling chambers or tubes  82  which are routed through the chamber  58  of the doctor blade system  36 . The cooling tubes  82  include a first set of cooling tubes  82 - 1  and a second set of cooling tubes  82 - 2 . The cooling tubes  82  may include enhanced surface features, such as fins, plate-fins, and/or other structures or surface treatments, to enhance the heat exchange effect. The second set of cooling tubes  82 - 2  are shown running through the chamber  58  so as to come into direct contact with at least a portion of the ink  30  disposed within the chamber  58 .  
         [0035]    Referring now to FIG. 9, the exchange unit  64  shown therein includes a plurality of cooling chamber or tubes  82  which are routed along an exterior portion  84  of the chamber  58  of the doctor blade system  36 . The cooling tubes  82  may run in contact with a number of exterior surfaces, for example the surfaces  86  and  88 , in order to cool the ink  30  housed within the chamber  58 . An insulating, protective, or restraining covering (shown in dotted lines) may be placed over the tubes.  
         [0036]    Referring now to FIGS. 10 and 11, an electronic cooling system  90  may be provided in place of, or in addition to, the more conventional refrigerant-based cooling system outlined above. In the embodiment of FIGS. 10 and 11, an electronic cooling component  92  is mounted to the exterior portion  84  of the doctor blade system  36  (FIG. 10), or, as an alternative, the cooling component  92  may be mounted to the doctor blade system  36  so as to extend into the chamber  58  so as to come into direct contact with at least a portion of the ink  30  housed therein. The electronic cooling component  92  may be a thermoelectric cooling device employing what is known as “the Peltier Effect”. Such a cooling component  92  is a solid-state method of heat transfer through dissimilar semiconductor materials. Such electronic cooling components  92  are commercially available. One possible source is ThermoElectric Cooling America of Chicago, Ill. As is known, an electronic cooling system replaces the main working components of a conventional refrigerant-based system with a cold junction, a heat sink and a DC power source. The refrigerant in both liquid and vapor form is replaced by two dissimilar conductors. The cold junction (evaporator surface) becomes cold through absorption of energy by the electrons as they pass from one semiconductor to another, instead of energy absorption by the refrigerant as it changes from liquid to vapor. The compressor is replaced by a DC power source which pumps the electrons from one semiconductor to another. A heat sink replaces the conventional condenser fins, discharging the accumulated heat energy from the system.  
         [0037]    Referring now to FIG. 12, an ink cooling system assembled in accordance with the teachings of yet another disclosed example of the present invention is shown and is generally referred to by the reference numeral  102 . The ink cooling system  102  is shown in conjunction with the anilox roll  32 , and the ink cooling system  102  is operatively connected to the ink train system  28  of the type discussed above with respect to the earlier disclosed examples. It will be understood that the ink train system  28  (not shown in FIG. 12), includes an ink supply line  48 , and an ink return line  50  which operate to route the ink  30  from the ink tank (not shown) in a manner similar to that discussed above (which may be similar or identical to the same elements as discussed above with respect to the earlier disclosed examples).  
         [0038]    The ink cooling system  102  is incorporated into a doctor blade system, such as the doctor blade system  36  discussed above with respect to the earlier disclosed examples. It will be appreciated that the doctor blade system  36  extends essentially along a length of the anilox roll  32  such that the doctor blade system includes a first end  104  and a second end  106  which are disposed generally adjacent to opposing ends  32   a  and  32   b , respectively of the anilox roll.  
         [0039]    Referring now to FIGS. 13 and 14, the doctor blade system  36  is shown adjacent to the anilox roll  32 . The doctor blade system  36  includes a housing  108  which defines an ink cavity  110 . The ink cavity  110  is arranged to contain a quantity of the ink  30  between interior wall  112  of the housing  108  and the anilox roll  32 . The doctor blade system  36  includes a pair of end caps  114 ,  116  (the end cap  116  is visible in FIG. 12 only). The end cap  114  is mounted to an end  118  of the housing  108  while the end cap  116  is mounted to an end  120  of the housing  108 . Each end cap  114 ,  116  is secured to the housing  108  using a plurality of attachment bolts  122 . Each end cap  114 ,  116  includes a seal  124 , which preferable is a compressible seal of the type commonly employed in the art and which abuts the anilox roll  32  in a known manner in order to seal the ends of the cavity  110 .  
         [0040]    The doctor blade system  36  also includes an upper blade  126  and a lower blade  128 , both of which extend generally along the length of the housing  108 . Each blade  126 ,  128  includes a hold down bar  130 ,  132 .  
         [0041]    Referring again to FIG. 12, the doctor blade system  36  is operatively connected to the ink supply line  48 , and may include one or more ink return lines  50 . The ink cooling system  102  is also connected to the coolant supply line  66  and the coolant return line  68 , both of which are operatively connected to a refrigeration unit (not shown, but which may be similar to the regrigeration unit discussed above with respect to the earlier disclosed examples), or to any other refrigeration unit capable of supplying a suitable coolant medium to the ink cooling system  102 .  
         [0042]    Preferably, the housing  108  is provided with a pair of headers  134 ,  136  (the header  136  is visible in FIG. 12 and schematically in FIGS.  17 - 19 ). The headers  134 ,  136  are disposed generally adjacent to the ends  118 ,  120 , respectively of the housing  108 . In the example shown, the coolant supply line  66  is routed to the header  136 , while the coolant return line  68  is routed to the header  134 .  
         [0043]    Referring now to FIG. 15, the housing  108  includes a pair of internal flow passages  138 ,  140 . The flow passages  138 ,  140  are defined in the cross section of the housing  108 , generally between the interior wall  112  of the housing  108  and an exterior wall  142  of the housing  108 . The coolant flow passages  138 ,  140  are in flow communication with the coolant supply and return lines  66 ,  68 , such that the coolant entering the coolant supply line  66  will flow through the housing  108  via the passages  138 ,  140  and exit the housing  108  via the coolant return line  68 . Thus, in accordance with the disclosed example, the ink  30  contained within the ink cavity  110  of the housing  108 , which ink  30  may be warmer than is desired, will be cooled via heat transfer taking place between the warmer ink  30  and the coolant contained in the flow passages  138 ,  140 .  
         [0044]    Referring now to FIG. 16, the housing  108  shown therein is equipped with a plurality of coolant flow passages  144 , which are greater in number than the pair of flow passages  138 ,  140  as discussed with respect to FIG. 15. Other than the difference in the number of flow passages, the construction and operation of the ink cooling system  102  illustrated in FIG. 16 may be substantially similar to the structure and operation of the ink cooling system  102  shown in FIG. 15. With regard to both FIGS. 15 and 16, it will be appreciated that the housing  108  may be supplied with suitable ports or connections in order to route the coolant contained in the appropriate coolant flow passages from the appropriate ends of the housing  108  to the adjacent headers  134 ,  136  and thus to the coolant supply or return lines  66 ,  68 . Also, in accordance with the disclosed example, the housing  108  shown in either FIG. 15 or  16  may be constructed of, for example, extruded or cast aluminum, or any other suitable material.  
         [0045]    Referring now to FIGS.  17 - 20 , it will be appreciated that the ink cooling system  102  may be readily adaptable to utilize either a parallel flow arrangement (FIG. 17) or a counter flow arrangement (FIGS.  18 - 20 ). It will further be appreciated that the ink cooling system may be provided with only a single header  134  at the end  118  of the housing  108 , or alternatively, the ink cooling system  102  may incorporate the pair of headers  134 ,  136 . A single flow path (FIGS.  18 - 20 ) or multiple flow paths (FIG. 17) may be provided. It will also be appreciated that the coolant supply line  66  and the coolant return line  68  may be in flow communication with the headers  134 ,  136  (FIGS. 17 and 18), or, as an alternative, the coolant supply line  66  and the coolant return line  68  may be in flow communication with only a single one of the headers, for example the header  134  illustrated in FIGS. 19 and 20.  
         [0046]    In the disclosed examples, it will be understood that the headers  134  may be provided with suitable passages or ports  146 , while the headers  136  may be provided with suitable passages or ports  148 , in order to be in flow communication with the coolant flow passages  138 ,  140 , or  144 . Additionally, the passages may be internally interconnected, with such an example shown schematically in FIG. 20 adjacent the end  120 .  
         [0047]    In accordance with one or more of the disclosed examples, the doctor blade system  36  including the ink chamber typically extends along all or major portion of the length of the anilox roll  32 . It is known that in many commercial applications the anilox roll  32  may be, for example, between about 4 feet and 8 feet in length. Typically, the end caps  114 ,  116  measure, for example, about one half inches thick. Typically, the seals  124  are formed of a foam-like material that is sandwiched between the appropriate end cap  114 ,  116  and the adjacent ends of the chamber  118 ,  120 , respectively. The seals  124  are also held in place by the hold down bars  130 ,  132 , which hold the doctor blades  126 ,  128  in place. The seals  124  are compressed against the surface of the anilox roll  32  and thus seal the ends of the ink chamber.  
         [0048]    The anilox roll  32  typically has millions of cells. As the anilox roll  32  rotates, the cells rotate through the ink  30  contained within the chamber such that the cells fill with ink. Along the length of the anilox roll the blades  126 ,  128  act as seals to seal the chamber along the length of the anilox roll  32 , and also scrape off any excess ink, thus leaving only what is contained in the cells for application to the raised image on the next cylinder (not shown) which is typically disposed on the opposite side of the anilox roll  32 .  
         [0049]    Although certain apparatus constructed in accordance with the teachings of the invention have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all embodiments of the teachings of the invention fairly falling within the scope of the appended claims either literally or under the doctrine of equivalence.