Abstract:
A chamber blade/sealing assembly for use with a fluid chamber which supplies fluid to a roll, includes a containment blade including an elongated thin plate having opposite ends; and a wear element which increases at least one of stiffness and wear of the thin plate, mounted to a surface of the thin plate at the opposite ends thereof. First and second end seals for sealing first and second ends of the fluid chamber, each include a supporting wall, an upper concave surface on the supporting wall and adapted to engage an outer surface of the roll, and a first upper supporting surface extending from one end of the upper concave surface, the first upper supporting surface adapted to receive the wear element such that the wear element does not substantially increase pressure from the roll on the containment blade at the first upper supporting surface.

Description:
REFERENCE TO RELATED APPLICATION 
     The present application is a continuation-in-part of pending U.S. patent application Ser. No. 12/710,763, filed Feb. 23, 2010 and having one of the inventors thereof as the common inventor herein and entitled IMPROVED DOCTOR/CONTAINMENT BLADE FOR A PRINTING PRESS. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a sealing assembly for an ink chamber associated with an anilox roll and chamber blade assembly, and more particularly, is directed to an improved doctor/containment blade with an improved blade/seal area between the doctor blade and containment blade and the chamber seal. 
     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. 
     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 containment 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. 
     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 containment blade held to the inlet end, with the free ends of the blades being in contact with the outer surface of the anilox roll. 
     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. 
     Examples of doctor blades used in such arrangement are shown in U.S. Pat. Nos. 5,638,751 and 6,546,861. 
     Each seal is formed by a compressible or deformable 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. 
     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, due in part to the flimsiness of the thin blades, pressure on the blades, dried ink under the blades, fluid pressure in the chamber, etc. Thus, the areas where the anilox roll, blades and seals join are susceptible to leakage because of geometric changes. 
     The above U.S. patent application Ser. No. 12/710,763 provides a solution to the above problems by providing an improved doctor blade and containment blade with additional wear resistance, improved leakage resistance, increased rigidity and increased wear life at the position of the end seals. This is accomplished by a wear element which increases the stiffness and/or wear of the thin plate of the blades, the wear element mounted to a surface of the thin plate at least at a position corresponding to the end seals, such that the thickness of the reinforced blade is greater at the opposite ends thereof which lie against the seals than at positions thereof between the end seals. 
     However, the wear element increases the thickness of the blade thereat. Because of the extra thickness thereat, when the wear element hits the anilox roll, there is increased force by the anilox roll on the blade at this position, which can result in undesirable effects. Specifically, because of this increased force on the blade, the blade wears faster thereat, even though the life of the blade at this position is still longer than a blade without the wear element. There are also wiping problems thereat which can cause dripping of the ink. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved containment blade with an improved sealing function with the seals associated therewith at the ends of the ink chamber. 
     It is another object of the present invention to provide an improved containment blade with additional wear resistance at the position of the end seals. 
     It is a still further object of the present invention to provide an improved containment blade that provides improved leakage resistance at the end seals. 
     It is a yet further object of the present invention to provide an improved containment blade that provides increased wear life thereof. 
     It is another object of the present invention to provide an improved containment blade having increased rigidity at the end seals. 
     It is still another object of the present invention to provide an improved containment blade that eliminates the aforementioned wiping problems. 
     It is yet another object of the present invention to provide an improved containment blade that is easy to use and economical to manufacture. 
     In accordance with an aspect of the present invention, a chamber blade/sealing assembly for use with a fluid chamber which supplies fluid to a roll, includes a containment blade including an elongated thin plate having opposite ends; and a wear element which increases at least one of stiffness and wear of the thin plate, the wear element mounted to a surface of the thin plate at the opposite ends thereof. First and second end seals for sealing first and second ends of the fluid chamber are provided. Each of the first and second end seals include 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 extending from one end of the upper concave surface, the first upper supporting surface adapted to receive the wear element such that the wear element does not substantially increase pressure from the roll on the containment blade at the first upper supporting surface. 
     In one embodiment, the first upper supporting surface includes a recess therein, and the wear element is positioned within the recess. The recess can be bounded by a raised wall at at least one end thereof. Preferably, the wear element has a shape and dimensions similar to those of the recess. 
     Preferably, the wear element is a plate material made from the same material as the blade, and has a thickness at least equal to a thickness of the blade. 
     The first upper supporting surfaces are formed by downwardly sloping flat supporting surfaces which continue at an angle from one edge of the upper concave surface. 
     In addition, a height of each first upper supporting surface at any point thereon is lower than would be required for a chamber blade/sealing assembly without said wear element, in order to account for extra thickness of the containment blade and wear element together. 
     The end seal is made of one of a compressible and deformable material, and the compressible and deformable material of a portion of said seal containing the first upper supporting surface has a durometer which is less than a durometer of the compressible and deformable material of a remainder of said seal. 
     In accordance with another aspect of the present invention, a chamber blade/sealing assembly for use with a fluid chamber which supplies fluid to a roll, includes a containment blade including an elongated thin plate having opposite ends; and a wear element which increases at least one of stiffness and wear of the thin plate, the wear element mounted to a surface of the thin plate at the opposite ends thereof. First and second end seals for sealing first and second ends of the fluid chamber are provided. Each of the first and second end seals include 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 extending from one end of the upper concave surface, the first upper supporting surface adapted to receive the wear element such that an effective thickness of the containment blade and the wear element together between the seal and the roll remains substantially the same as the thickness of the containment blade alone. 
     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 
         FIG. 1  is a cross-sectional view of a conventional blade seal associated with an anilox roll; 
         FIG. 2  is a perspective view of the seal of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the conventional seal of  FIG. 1 , showing the containment blade bending away from the seal; 
         FIG. 4  is a side elevation view of a modified containment blade according to the prior art; 
         FIG. 5  is a perspective view of a doctor blade and containment blade according to the invention of U.S. patent application Ser. No. 12/710,763, in association with an end seal and an anilox roll; 
         FIG. 6  is a side elevation view, partly in cross-section, of the arrangement of  FIG. 5 , but showing only the containment blade; 
         FIG. 7  is a perspective view of a modified containment blade according to the invention of U.S. patent application Ser. No. 12/710,763, in association with an end seal and an anilox roll; 
         FIG. 8  is a side elevation view of the arrangement of  FIG. 7 , but showing only the containment blade; 
         FIG. 9  is a top plan view showing wearing of a containment blade at the end where it seats on the end seal; 
         FIG. 10  is a perspective view of an end seal according to one embodiment of the present invention; 
         FIG. 11  is a side elevation view, partly in cross-section, showing the containment blade according to  FIG. 10 , in association with an end seal and an anilox roll; 
         FIG. 12  is a perspective view of an end seal according to another embodiment of the present invention; 
         FIG. 13  is a perspective view of an end seal according to still another embodiment of the present invention; and 
         FIG. 14  is a perspective view of an end seal according to yet another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings in detail, and initially to  FIGS. 1-4  thereof, there is shown a conventional sealing assembly  10  for doctor and containment 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 surrounds anilox roll  12 . Anilox roll  12  rotates in the direction of arrow  12   a.    
     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 , an elongated sealing or containment blade  18  and an elongated doctor blade  20  are provided at the entry and exit positions of anilox roll  12  relative to ink chamber  14 . Blades  18  and  20  each include a clamping portion that is fixed to chamber housing  16  by a blade holder (not shown) at a position beyond the chamber housing  16 , as is well known in the art, 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 . 
     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 supporting surfaces  22   b  and  22   c  which support blades  18  and  20 , respectively. 
     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 containment blade  18  held to the inlet end, with the roll contact portions, that is, the free contact edges, of blades  18  and  20  being in contact with the outer surface of anilox roll  12 . 
     However, each end of blades  18  and  20  sits upon a supporting surface  22   b  or  22   c  of a respective seal  22 . As a result, in part because of the flimsiness or thinness of the blades, a gap may be created at the opposite ends of the blades  18  and  20  where they are in contact with 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 supporting surfaces  22   b  and  22   c  of the respective seal  22 , as shown in  FIG. 3 . Thus, the areas where anilox roll  12 , blades  18  and  20  and seals  22  join are susceptible to leakage because of geometric changes. 
     In addition, another problem at the end seals is that of back blading. Specifically, as anilox roll  12  rotates, each position thereon reenters the ink chamber  16 . During this rotation when containment blade  18  is the upper blade, ink thereat catches on containment blade  18  and builds up at this position. The ink then builds up and runs along the interface of containment blade  18  and anilox roll  12 , and drips down from the edge of containment blade  18  in the seal area. When containment blade  18  is the lower blade, the ink merely drips down and creates stalactites of ink. 
     As a result, in order to prevent or limit back blading, it is known to increase the width of containment blade  18 , for example, from 25 mm to 35 mm, with the extra width section  18   a  thereof being bent such that the portion of containment blade  18  in contact with anilox roll  12  is at an acute angle α which is much less than the angle β of contact of a conventional 25 mm blade, as shown in  FIG. 4 . Such an increased width blade is sold by Paper Converting Machine Co. of Green Bay, Wis. However, in such known arrangement, the section of extra width portion  18   a  that would normally lie between anilox roll  12  and seal  22  is cut away. In other words, extra width portion  18   a  only exists between seals  22 , but not at seals  22 . This is because the geometry of the blade  18  must be taken into considered for transitioning between the straight seal surfaces  22   b  and  22   c  and the round surface of anilox roll  12 , and the cut-out portion must be determined ahead of time in order to determine how the blade will lie against anilox roll  12  and seal surfaces  22   b  and  22   c . The geometry of the cut-away portion can also change in dependence on the position of the chamber relative to anilox roll  12 . 
     Referring now to  FIGS. 5 and 6 , blades  18 ,  20  according to the invention of U.S. patent application Ser. No. 12/710,763, each include a wear element  21  fixedly mounted thereon at a position at or spaced slightly from the initial roll contact portion of each blade  18 ,  20  with anilox roll  12 , and positioned at least in the area where each blade  18 ,  20  lies on downwardly sloping flat supporting surfaces  22   b  and  22   c  of seal  22 , and may even extend into the clamped portions thereof. Preferably, each wear element  21  extends in the lengthwise direction of each blade  18 ,  20  so as to at least partially overlap downwardly sloping flat supporting surfaces  22   b  and  22   c  in that lengthwise direction. However, the length of each wear element  21  can be less than or greater than the dimension of each downwardly sloping flat supporting surface  22   b  and  22   c  in the lengthwise direction of each blade  18 ,  20 . If wear element  21  also extends, for example, partially or entirely across the entire blade, it is important that wear element  21  have a greater thickness in areas where it overlaps downwardly sloping flat supporting surfaces  22   b  and  22   c . Thus, it will be appreciated that, even if wear elements  21  extend between the seal areas, the thickness of wear elements  21  is greatest at the seal areas, so that the rigidity of blades  18 ,  20  is increased greatly at the seal areas. 
     The width of each wear element  21  preferably extends to the outer edge of the respective flat supporting surface  22   b  and  22   c , but is not limited thereto, and may vary in width therefrom. Each wear element  21  can be of any suitable thickness. Wear element  21  can be made of any suitable material, such as the same material as blades  18 ,  20 . 
     With wear elements  21  added to each blade  18 ,  20 , the rigidity of each blade  18 , 20  at downwardly sloping flat supporting surfaces  22   b  and  22   c  of seal  22 , is increased. As a result, there is much less tendency for each blade  18 , to bow at the position of seals  22 . In effect, each wear element  21  inhibits or prevents ink from entering into the area between blades  18 ,  20  and downwardly sloping flat supporting surfaces  22   b  and  22   c  of seals  22 , thereby inhibiting or preventing leakage of ink at the seal areas. 
     It is noted that, at each seal area, the respective blade  18 ,  20  may wear down faster than at areas between the seal areas where the blades  18 ,  20  are in contact with anilox roll  12 , since there is little or no lubricating ink at the seal areas. As a result, an opening may develop in each blade  18 ,  20  at the seal areas through which ink can leak, particularly if the blades  18 ,  20  are bowed outwardly. This ink leakage under the blades  18 ,  20  tends to push the respective blades  18 ,  20  further away from downwardly sloping flat supporting surfaces  22   b  and  22   c  of seal  22 , which results in further leakage of ink thereat. By providing the extra material thickness of wear elements  21 , even if a wear opening is provided in each blade  18 ,  20 , the blade is not pushed away from downwardly sloping flat supporting surfaces  22   b  and  22   c  of seal  22 , due to the increased rigidity of the blades  18 ,  20  at the seal areas, so that there is little or no ink leakage. Further, as the blade wears down in the seal area, the anilox roll  12  comes into contact with the increased thickness wear element  21 , whereby the additional material of wear element  21  functions to increase the wear life of the blade. 
     It will be appreciated that, while wear element  21  is preferably secured to blades  18 ,  20 , it may be provided as a separate element held by the machine and which lies against the same area of blades  18 ,  20  described herein. Therefore, reference to wear element  21  being “mounted” refers to wear element  21  being fixed to blades  18 ,  20 , or as a separate element pressed thereagainst. 
     Further, as shown in  FIGS. 7 and 8 , if the width of containment blade  18 , is increased, for example, from 25 mm to 30 mm or 35 mm, with the extra width section  18   a  thereof being bent such that the portion of containment blade  18  in contact with anilox roll  12  is at an acute angle α which is much less than the angle  13  of contact of a conventional 25 mm blade, as shown in  FIG. 4 , but in which the extra width section  18   a  is not cut away at the seal areas, contrary to the blades sold by Paper Converting Machine Co. of Green Bay, Wis., each wear element  21  functions to increase the wear life of the blade, while also preventing or inhibiting back blading. Specifically, the section of extra width portion  18   a  that would normally lie between anilox roll  12  and seal  22  is not cut away. 
     In such case, extra width portion  18   a  is also positioned between anilox roll  12  and seal  22 , as shown in  FIGS. 7 and 8 . In this position, extra width portion  18   a  sinks into the compressible or deformable material of seal  22  so that the inner surface of extra width portion  18   a  is flush or coextensive with the inner arcuate surface  22   a  of seal  22 . In this regard, seal  22  is made of any suitable deformable or compressible material, such as felt, a closed cell foam or an elastomeric material having a desired durometer. The pressure of anilox roll  12  on extra width portion  18   a  results in wear of this extra width portion  18   a , creating an open area  19 , as shown in  FIG. 9 . This wearing of containment blade  18  at this position results in wearing away open area  19  ( FIG. 9 ) of blade  18  through which ink can leak between blade  18  and end seals  22  at the ends of anilox roll  12 . Because there is uneven wear of blade  18  adjacent seals  22 , this would normally tend to cause leakage of ink at the ends of anilox roll  12 . 
     However, by additionally providing wear element  21 , leakage does not occur, even with such open area  19 . As a result, in tests performed by the applicant herein, a containment blade  18  with an extra width portion  18   a  but without wear elements  21 , leaked in a flexographic printing machine in about 12 hours. However, the same blade  18  in the same flexographic printing machine and under the same conditions, but with wear elements  21  added of the same material and thickness as blade  18 , was still functioning with little or no ink leakage even after 24 hours of operation, even though a similar open area  19  was created. Because wear element  21  is in contact with anilox roll  12 , the wear life of blade  18  is greatly increased. 
     Thus, the invention of U.S. patent application Ser. No. 12/710,763, provides that the material of blade  18  is sufficiently flexible to bend and pass between anilox roll  12  and seal  22 , while made sufficiently rigid by wear element  21  to prevent leakage beneath blade  18 , even when worn away to provide an open area  19  thereof. 
     Although wear element  21  has been shown mounted on the outer surface of each blade  18 ,  20  outside of the ink chamber, it can be mounted on the inner surface within the ink chamber. 
     The invention of the above U.S. patent application Ser. No. 12/710,763 thereby provides an improved doctor blade and containment blade with additional wear resistance, improved leakage resistance, increased rigidity and increased wear life at the position of the end seals. This is accomplished by a wear element which increases the stiffness and/or wear of the thin plate of the blades, the wear element mounted to a surface of the thin plate at least at a position corresponding to the end seals, such that the thickness of the reinforced blade is greater at the opposite ends thereof which lie against the seals than at positions thereof between the end seals. 
     However, wear element  21  increases the thickness of the blade thereat. Because of the extra thickness thereat, when wear element  21  hits the anilox roll, there is increased force by the anilox roll on the blade at this position, which can result in undesirable effects. Specifically, because of this increased force on the blade, the blade wears faster thereat, even though the life of the blade at this position is still longer than a blade without wear element  21 . There are also wiping problems thereat which can cause dripping of the ink. 
     Referring now to  FIGS. 10 and 11 , the present invention overcomes this problem of increased force on the blade and the wiping problems. Specifically, wear element  21  is secured to the opposite surface of containment blade  18 . Further, downwardly sloping supporting surface  22   b  of seal  22 , which supports containment blade  18  includes a recess  22   d  which is preferably, but not limited to, configured to have dimensions similar to or smaller than wear element  21 , and a depth similar to the initial thickness of wear element  21  so that the outer surface of wear element  21  is coplanar with downwardly sloping supporting surface  22   b  of seal  22 . As a result, the effective thickness of containment blade  18  and wear element  21  against anilox roll  12  is the same as the thickness of containment blade  18  at other positions without wear element  21 . This means that there is no increased force by anilox roll  12  on containment blade  18  at this position. Therefore, since there is no increased force on containment blade  18 , containment blade  18  does not wear faster at the position of wear element  21 . However, because of wear element  21 , even if there is wear through containment blade  18  at this position, there is still wear element  21  thereat, which greatly increases the life of containment blade  18  over conventional containment blades  18  without wear element and increases the life over containment blade  18  with wear element  21  according to U.S. patent application Ser. No. 12/710,763. In addition, because there is no increased force at this position, the wiping problems associated with containment blade  18  of U.S. patent application Ser. No. 12/710,763, are not present, thereby avoiding the problem of dripping of ink. 
     It will be appreciated that the present invention is also applicable to the modification of  FIGS. 7-9  herein. 
     It will be appreciated that, instead of a recess  22   d  which is bounded at opposite ends thereof by raised walls, as shown in  FIG. 10 , recess  22   d  can be bounded by a raised wall at only one end, for example, the upper end, as shown in  FIG. 12 . Alternatively, in place of a recess  22   d , downwardly sloping supporting surface  22   b  can merely be provided with a height at any point thereon which is lower than would be required for a chamber blade/sealing assembly without wear element  21 , in order to account for extra thickness of the containment blade  18  and wear element  21  together. The latter modification, in effect, provides an effective recess  22   d  which is unbounded by raised walls, that is, there are no raised walls at either end thereof. 
     As a further alternative, in place or recess  22   d  or lower height downwardly sloping supporting surface  22   b , the height of downwardly sloping supporting surface  22   b  can be the same as that of a downwardly sloping supporting surface  22   c  which would be required for a chamber blade/sealing assembly without wear element  21 . However, at least a portion  22   e  of seal  22  shown by dashed lines in  FIG. 14 , at downwardly sloping supporting surface  22   b , is formed from a material that has a durometer that is lower than the durometer of the material of the remainder of seal  22 . In such case, wear element  21  would sink further into the material of seal  22  at downwardly sloping supporting surface  22   b , so that the effective thickness of wear element  21  and containment blade  18  at this position, as seen in the side view, is effectively the same as containment blade  18  alone, so that wear element  21  does not increase the pressure thereat. Portion  22   e  can be modified from that shown in  FIG. 14 , as long as the desired effect is still achieved. 
     It will be appreciated that combinations of the above embodiments can be provided. For example, the recess  22   d  or lowered height downwardly sloping supporting surface  22   b  need not have a height corresponding to the thickness of wear element  21 , but can have a height less than the thickness of wear element  21 . In such case, recess  22   d  or lowered height downwardly sloping supporting surface  22   b  can be combined with a lower durometer material thereat to provide the same result. 
     The key to all of the above embodiments is that wear element  21  increases the life of containment blade  18 , while not increasing the pressure or force thereon at the position of end seal  22 . 
     In this regard, it will be appreciated that containment blade  18 , rather than wear element  21 , can be in direct contact with downwardly sloping supporting surface  22   b  or recess  22   d , as long as the effective thickness of containment blade  18  and wear element  21  between seal  22  and roll  12  remains substantially the same as the thickness of containment blade  18  alone. 
     Having described specific preferred embodiments of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to those precise embodiments 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.