Abstract:
A seal adapted to seal an end of a fluid chamber which supplies fluid to a roll, includes at least one supporting wall and an upper concave surface on the at least one supporting wall and adapted to engage an outer surface of the roll. First and second, sloping, upper supporting surfaces are formed at opposite ends of the upper concave surface for receiving an end of a doctor/sealing blade thereon. Four flexible, resilient upstanding wings are provided along side edges of the first and second upper supporting surfaces for providing a sealing engagement with the doctor/sealing blades, even when the doctor/sealing blades bow outwardly away from the first and second upper supporting surfaces.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a sealing assembly for an ink chamber associated with an anilox roll and chamber doctor blade assembly, and more particularly, is directed to a sealing assembly with an improved blade/seal area when the doctor and sealing blades associated therewith bend at their ends. 
         [0002]    Conventionally, in printing machines, such as flexographic printing machines, an ink transfer or anilox roll transfers ink to an adjacent plate roll for printing. Ink is supplied to the anilox roll from an ink chamber defined by a chamber housing which partially surrounds the anilox roll. Specifically, ink is supplied through an ink supply tube and then through an ink supply line in the chamber housing, into the ink chamber. In like manner, ink is removed from the ink chamber through an ink return line in the chamber housing and then through an ink return tube. 
         [0003]    In order to prevent the escape of ink from the chamber, while ensuring that the ink enters the cells in the anilox roll and has a predetermined volume on the anilox roll, doctor and sealing blades are provided at the exit and entry positions of the anilox roll relative to the ink chamber. The blades are fixed to the chamber housing so that the blades overhang the chamber housing and contact the anilox roll. 
         [0004]    With this arrangement, the outer surface of the anilox roll passes through the ink chamber and picks up ink for printing. The ink is metered by means of the doctor blade held to the outlet end of the chamber housing, and sealed with a sealing blade held to the inlet end, with the free ends of the blades being in contact with the outer surface of the anilox roll. 
         [0005]    A seal is provided at each end of the blade, that is, at each end of an anilox roll for sealing the ends thereof. Examples of such arrangements are shown in U.S. Pat. Nos. 6,739,248; 6,672,207; 6,598,525; 5,983,797; 5,735,210; 5,662,042; and 5,150,651. 
         [0006]    Each seal is formed by a compressible body. Since the seals provided at each end of the anilox roll function to seal the ends of the ink chamber, each seal must lie against the peripheral surface of the rotating anilox roller. As a result, each seal is therefore exposed to mechanical stresses as well as wear. Further, during the printing operation, the blades, which press against the anilox roll, also wear. The geometry of the sealing function between the anilox roll, the two blades and the end seal changes. 
         [0007]    Conventionally, each end of a blade sits upon a flat supporting area of the respective seal. As a result, a gap may be created at the opposite ends of the blades where they are held by the chamber seals. However, there is uneven wear on the ends of the blades adjacent the seals, which tends to cause leakage of ink at the ends of the anilox roll. As the doctor blades are forced against the anilox roll and, in particular, when the doctor blades wear unevenly in the sealing area, the sealing and doctor blades may flex or bow outwardly relative to the flat supporting area of the seal. Thus, the areas where the anilox roll, blades and seals join are susceptible to leakage because of geometric changes. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, it is an object of the present invention to provide a seal for sealing ends of an ink chamber having doctor and sealing blade seals associated therewith, that overcomes the aforementioned problems. 
         [0009]    It is another object of the present invention to provide a seal for sealing ends of an ink chamber having doctor and sealing blade seals associated therewith, which ensures a sealing arrangement with the doctor and sealing blades at the ends of the seal, even when even when the doctor and sealing blades bow outwardly away from the downwardly sloping flat supporting surfaces at the ends of the seal. 
         [0010]    It is a still further object of the present invention to provide a seal for sealing ends of an ink chamber having doctor and sealing blade seals associated therewith, that is easy to use and economical to manufacture. 
         [0011]    In accordance with an aspect of the present invention, a seal adapted to seal an end of a fluid chamber which supplies fluid to a roll, includes at least one supporting wall and an upper concave surface on the at least one supporting wall and adapted to engage an outer surface of the roll. A first upper supporting surface is formed at one end of the upper concave surface for receiving an end of a doctor/sealing blade thereon, and at least one flexible, resilient member is connected with the upper supporting surface for providing a sealing engagement with the doctor/sealing blade, even when the doctor/sealing blade bows outwardly away from the first upper supporting surface. 
         [0012]    Preferably, the at least one flexible member includes at least one wing upstanding from the first upper supporting surface. 
         [0013]    Generally, there is also a second upper supporting surface at an opposite end of the upper concave surface for receiving an end of another doctor/sealing blade thereon; and at least one the flexible, resilient member connected with the second upper supporting surface for providing a sealing engagement with the other doctor/sealing blade, even when the other doctor/sealing blade bows outwardly away from the second upper supporting surface. In such case, the seal includes four corner sections, and there is one wing at least at two of the corner sections. 
         [0014]    Each wing extends along a side edge of the first upper supporting surface at an angle relative to a lengthwise direction of the seal. Preferably, there are at least two wings on opposite sides of the first upper supporting surface which face each other, and inner surfaces of the facing wings have a bowed shape. The bowed shape includes a convex bowed shape from one end to an opposite end of the inner surface of each wing and convex bowed shape from a lower end to an upper end of the inner surface of each wing. An outer surface of each wing is substantially planar such that each wing tapers in thickness from the lower end to the upper end thereof. 
         [0015]    The first upper supporting surface slopes down from an inner end thereof to an outer end thereof at an inclined angle relative to a lengthwise direction of the seal, and is formed as a continuation of the upper concave surface. 
         [0016]    In accordance with another aspect of the present invention, a seal adapted to seal an end of a fluid chamber which supplies fluid to a roll, includes at least one supporting wall, an upper concave surface on the at least one supporting wall and adapted to engage an outer surface of the roll, and a first upper supporting surface at one end of the upper concave surface for receiving an end of a doctor/sealing blade thereon. The first upper supporting surface has an outwardly bowed shape in an unbiased condition thereof. The first upper supporting surface is also flexible and resilient for providing a sealing engagement with the doctor/sealing blade, even when the doctor/sealing blade bows outwardly away from the first upper supporting surface. 
         [0017]    Preferably, there is a second upper supporting surface at an opposite end of the upper concave surface for receiving an end of another doctor/sealing blade thereon. The second upper supporting surface also has an outwardly bowed shape in an unbiased condition thereof. The second upper supporting surface being flexible and resilient for providing a sealing engagement with the other doctor/sealing blade, even when the other doctor/sealing blade bows outwardly away from the second upper supporting surface. 
         [0018]    In one embodiment, the entire seal, including the first upper supporting surface, is made from a foam material. 
         [0019]    The above and other objects, features and advantages of the invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a cross-sectional view of a conventional doctor blade seal associated with an anilox roll; 
           [0021]      FIG. 1A  is a perspective view of the seal of  FIG. 1 ; 
           [0022]      FIG. 1B  is a cross-sectional view of the conventional doctor blade seal of  FIG. 1 , showing the doctor blade bending away from the seal; 
           [0023]      FIG. 2  is a perspective view of doctor and sealing blade seal according to the present invention; 
           [0024]      FIG. 3  is a side elevational view of the doctor and sealing blade seal of  FIG. 2 ; 
           [0025]      FIG. 4  is a top plan view of the doctor and sealing blade seal of  FIG. 2 ; 
           [0026]      FIG. 5  is a bottom plan view of the doctor and sealing blade seal of  FIG. 2 ; 
           [0027]      FIG. 6  is a cross-sectional view of the doctor and sealing blade seal of  FIG. 4 , taken along line  6 - 6  thereof; 
           [0028]      FIG. 7  is a cross-sectional view of the doctor and sealing blade seal of  FIG. 4 , taken along line  7 - 7  thereof; 
           [0029]      FIG. 8  is an end elevational view of the doctor and sealing blade seal of  FIG. 1 ; and 
           [0030]      FIG. 9  is a cross-sectional view of the doctor and sealing blade seal of  FIG. 3 , taken along line  9 - 9  thereof; 
           [0031]      FIG. 10  is a perspective view of a doctor and sealing blade seal according to another embodiment of the present invention; 
           [0032]      FIG. 11  is a cross-sectional view of the doctor and sealing blade seal of  FIG. 10 , associated with an anilox roll; 
           [0033]      FIG. 12  is a cross-sectional view of the doctor and sealing blade seal of  FIG. 11 , showing the doctor blade bending away from the seal. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Referring to the drawings in detail, and initially to  FIGS. 1 ,  1 A and  1 B thereof, there is shown a conventional sealing assembly  10  for doctor and sealing blades. Conventionally, in printing machines, such as flexographic printing machines, an ink transfer or anilox roll  12  transfers ink to an adjacent plate roll (not shown) for printing. Ink is supplied to anilox roll  12  from an ink chamber  14  defined by a chamber housing  16  which is adjacent to and may partially surround anilox roll  12 . Anilox roll  12  rotates in the direction of arrow  12   a.    
         [0035]    In order to prevent the escape of ink from ink chamber  14 , while ensuring that the ink enters the cells in anilox roll  12  and has a predetermined volume on anilox roll  12 , a sealing blade  18  and doctor blade  20  are provided at the entry and exit positions of anilox roll  12  relative to ink chamber  14 . Blades  18  and  20  are fixed to chamber housing  16  by a blade holder (not shown) so that blades  18  and  20  overhang chamber housing  16  and contact anilox roll  12 . Blades  18  and  20  are placed at an angle against the periphery of anilox roll  12  and help to define ink chamber  14  which extends along the length of anilox roll  12 . 
         [0036]    Seals  22  are provided at each end of anilox roll  12  to seal the ends of ink chamber  14 . Each seal  22  has an upper concave surface  22   a  which lies against the peripheral surface of the rotating anilox roll  12 . The edges of upper concave surface  22   a  continue in downwardly sloping flat supporting surfaces  22   b  and  22   c  which support blades  18  and  20 , respectively. 
         [0037]    With this arrangement, the outer surface of anilox roll  12  passes through ink chamber  14  and picks up ink for printing. The ink is metered by means of doctor blade  20  held to the outlet end of chamber housing  16 , and sealed with sealing blade  18  held to the inlet end, with the free ends of blades  18  and  20  being in contact with the outer surface of anilox roll  12 . 
         [0038]    However, each end of blades  18  and  20  sits upon a flat supporting surface  22   b  or  22   c  of a respective seal  22 . As a result, a gap may be created at the opposite ends of the blades  18  and  20  where they are held by the chamber seal  22 . Because there is uneven wear of blades  18  and  20  adjacent seals  22 , this tends to cause leakage of ink at the ends of anilox roll  12 . In such case, the sealing and doctor blades  18  and  20  may flex or bow outwardly relative to the flat supporting surfaces  22   b  and  22   c  of the respective seal  22 , as shown in  FIG. 1B . Thus, the areas where anilox roll  12 , blades  18  and  20  and seals  22  join are susceptible to leakage because of geometric changes. 
         [0039]    In accordance with the present invention, as shown in  FIGS. 2-9 , a deformable, compressible, flexible and resilient blade/ink chamber seal  122  for use in a sealing assembly according to the present invention for use with an anilox roll  12  and a sealing blade  18  and doctor blade  20 , includes spaced apart side walls  124  and  126  connected together at ends thereof by end walls  128  and  130  to thereby form a substantially rectangular box-like shape. 
         [0040]    Ledges  132  and  134  are connected to the upper ends of side walls  124  and  126  and extend inwardly therefrom. Slightly convex walls  136  and  138  extend inwardly and upwardly from the inner edges of ledges  132  and  134 , and walls  140  and  142  extend upwardly from the upper, inner edges of convex walls  136  and  138 . The upper edges of walls  140  and  142  form upper concave surfaces  144  and  146  which lie against the peripheral surface of the rotating anilox roll  12 . The openings  147  in the walls at the opposite ends of this open center area  145  are for providing lubrication in accordance with the teachings of applicant&#39;s U.S. patent application Ser. No. 11/502,647, filed Aug. 10, 2006, the entire disclosure of which is incorporated herein by reference, but which does not form part of the present claimed invention. 
         [0041]    Further, upper concave surfaces  144  and  146  at one end thereof are connected with one end to downwardly sloping flat supporting surface  148 , the opposite end of which is connected with the upper end of end wall  128 . In like manner, the opposite ends of upper concave surfaces  144  and  146  are connected with one end of downwardly sloping flat supporting surface  150 , the opposite end of which is connected with the upper end of end wall  130 . The width of downwardly sloping flat supporting surfaces  148  and  150  reduces from the lower ends thereof connected with end walls  128  and  130  to the opposite upper ends connected with upper concave surfaces  144  and  146 . Because of the reduction in width of downwardly sloping flat supporting surfaces  148  and  150 , it will be appreciated that the side edges thereof are angled relative to the lengthwise dimension of blade/ink chamber seal  122 . As shown best in  FIGS. 6 and 7 , downwardly sloping flat supporting surface  148  has a different slope than downwardly sloping flat supporting surface  150 , although the present invention is not limited thereby. Conventionally, downwardly sloping flat supporting surfaces  148  and  150  support blades  18  and  20 . 
         [0042]    However, as discussed, above, sealing and doctor blades  18  and  20  may flex or bow outwardly relative to downwardly sloping flat supporting surfaces  148  and  150 , resulting in leakage thereat. 
         [0043]    In accordance with the present invention, deformable, flexible and resilient wings  152  are formed at the four corners of blade/ink chamber seal  122 . Wings  152  preferably run along the side edges of downwardly sloping flat supporting surfaces  148  and  150  and extend upwardly therefrom. Preferably, inner surfaces  154  of wings  152  which face each other have a curved or bowed shape. Specifically, there is a convex bowed shape from one end  154   a  to the other end  154   b  of each inner surface  154 . In addition, each inner surface  154  curves outwardly from a bottom  154   c  thereof where it is connected to the respective downwardly sloping flat supporting surface  148  or  150 , to the upper free edge  156  of each wing  152 . The outer surface  158  of each wing  152  has a flat or planar shape and is substantially vertically oriented. As a result, the thickness of each wing  152  tapers from its lower connected end to its upper free end  156 . Further, as shown best in FIGS.  3  and  6 - 8 , the upper free edge  156  of each wing  152  preferably has a convex shape, although the present invention is not limited thereby. 
         [0044]    Because side edges of downwardly sloping flat supporting surfaces  148  and  150  are angled relative to the lengthwise dimension of blade/ink chamber seal  122 , wings  152  are also angled by this same amount. For example, wings  152  can be angled at about 15 degrees relative to the lengthwise direction of blade/ink chamber seal  122 , as shown in  FIG. 4 , although the present invention is not limited by this angle. 
         [0045]    When blades  18  and  20  are assembled in the sealing assembly, wings  152  are biased down and outwardly, and held down by pressure on blade/ink chamber seal  122 . During this initial assembly, because blades  18  and  20  are planar at their ends, the ends of blades  18  and  20  bias and push down wings  152  such that wings  152  are pressed down into a nearly coplanar arrangement relative to downwardly sloping flat supporting surfaces  148  and  150 . At this time, blades  18  and  20  are sealed at their ends by engagement with wings  152 . In addition, if wings  152  are biased sufficiently so as to be coplanar with downwardly sloping flat supporting surfaces  148  and  150 , blades  18  and  20  can also be sealed against downwardly sloping flat supporting surfaces  148  and  150 . 
         [0046]    However, as sealing and doctor blades  18  and  20  flex or bow outwardly relative to downwardly sloping flat supporting surfaces  148  and  150 , due to different pressures at their ends and uneven wear, wings  152 , because of their resilience, also move back upwardly with blades  18  and  20 . As a result, even if blades  18  and  20  flex or bow outwardly, wings  152  always maintain a sealing engagement therewith, substantially eliminating any leakage thereat caused by such flexing or outward bowing. 
         [0047]    It will be appreciated that the present invention is not limited to the above embodiment, but rather, is limited only by the claims herein. For example, the specific construction of blade/ink chamber seal  122  is given by example only, and any other suitable or conventional blade/ink chamber seal can be used, with the wings  152  added thereto. 
         [0048]    As another alternative, a plurality of smaller wings  152  can be provided along the side edges of downwardly sloping flat supporting surfaces  148  and  150 . Further, wings  152  can be provided inwardly of side edges of downwardly sloping flat supporting surfaces  148  and  150 . 
         [0049]    Further, although the present invention has been discussed in relation to wings  152  providing the constant sealing contact with blades  18  and  20 , it will be appreciated that any member that maintains a seal with the blades  18  and  20  as the blades  18  and  20  bow or flex outwardly can be used. For example, in place of wings  152 , a compressed foam material or the like can be used. 
         [0050]    Specifically, as shown in  FIGS. 10-12 , a compressible foam seal  222  according to another embodiment of the present invention, and which is provided at each end of anilox roll  12  to seal the ends of ink chamber  14 , has an upper concave surface  222   a  which lies against the peripheral surface of the rotating anilox roll  12 . The edges of upper concave surface  222   a  continue down at opposite ends thereof in outwardly bowed or convex shaped supporting surfaces  222   b  and  222   c  which support blades  18  and  20 , respectively. 
         [0051]    When blades  18  and  20  are assembled therewith, the planar ends of blades  18  and  20  compress convex shaped supporting surfaces  222   b  and  222   c  in the manner shown in  FIG. 11  so that convex shaped supporting surfaces  222   b  and  222   c  are compressed into planar shapes. 
         [0052]    Because there is uneven wear of blades  18  and  20  adjacent seals  222 , the sealing and doctor blades  18  and  20  may flex or bow outwardly, as discussed above. However, as sealing and doctor blades  18  and  20  flex or bow outwardly, the pressure on convex shaped supporting surfaces  222   b  and  222   c  by such ends of blades  18  and  20  is released so that convex shaped supporting surfaces  222   b  and  222   c,  due to their resilience, can return back to their convex shape. As a result, convex shaped supporting surfaces  222   b  and  222   c,  because of their resilience, also move back upwardly with blades  18  and  20 . As a result, even if blades  18  and  20  flex or bow outwardly, convex shaped supporting surfaces  222   b  and  222   c  always maintain a sealing engagement therewith, substantially eliminating any leakage thereat caused by such flexing or outward bowing. 
         [0053]    Having described a specific preferred embodiment of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to that precise embodiment and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope or spirit of the invention as defined by the appended claims.