Abstract:
A doctor blade system utilizes a lightweight doctor blade chamber to apply ink to an inking roller. The doctor blade chamber is removably positioned on a support plate which is, in turn, carried by linear guides on pivotable end plates. A rigid box beam is also attached to the end plates and is spaced from the support plate. A plurality of membrane cylinders are mounted on the rigid box beam and engage a surface of the support plate opposite to the surface that supports the doctor blade chamber. Through the application of suitable force, the support plate and its supported doctor blade chamber can be moved, by sliding motion on the linear slides, into uniform engagement with the surface of the ink roller. The system uses pivotable end plates which are supported by exterior plates that are, in turn, pivotably supported by press side frames. The chamber doctor blade and its support plate and box beam can be moved into several different positions, with respect to the cooperating ink roller, to facilitate doctor blade chamber cleaning or replacement or ink roller replacement.

Description:
FIELD OF THE INVENTION 
     The present invention is directed generally to a doctor blade system. More particularly, the present invention is directed to a doctor blade system for use in a rotary printing press. Most specifically, the present invention is directed to a doctor blade system for use in a flexographic printing machine. The doctor blade system includes a doctor blade chamber of a light material. A full length support plate carries the doctor blade chamber. That support plate is biased across its width, in the axial direction of a cooperating anilox roller, by a plurality of membrane cylinders. Those several membrane cylinders are secured to a rigid cross member. The result is a lightweight doctor blade chamber which is not subject to the bending and distortion problems that have been prevalent in previous devices. 
     BACKGROUND OF THE INVENTION 
     In the field of rotary printing machines, it is generally well known to provide an inking unit that is equipped with a chamber doctor blade assembly. Such a chamber doctor blade assembly will include an elongated doctor blade chamber which is provided with a central, ink receiving reservoir. The doctor blade chamber central ink receiving reservoir is defined by two spaced doctor blades which extend in the axial direction of a cooperating ink roller, typically an anilox or screen roller. End plates are used at both ends of the doctor blade body to define, in cooperation with the two spaced doctor blades, the ink receiving reservoir. 
     Ink is supplied to the reservoir in the doctor blade body and is then applied to the surface of the anilox roller from that reservoir while the surface of the anilox roller or other similar inking roller passes through the ink reservoir defined by the two doctor blades and end plates. It is necessary that the ink being applied to the surface of the anilox roller be accurately and uniformly metered. Either too little ink, too much ink or an unequal ink thickness along the axial length of the anilox roller will cause degradation of the quality of the resultant printed product. 
     The force with which the two spaced doctor blades are engaged against the surface of the anilox roller is one way to meter the thickness of the ink layer which is applied to the surface of the anilox roller. While factors such as ink viscosity, roller rotational speed and the like will also affect the ink thickness, it is the force with which the doctor blades engage the pocketed or cell-covered surface of the anilox roller which is more determinative of the thickness of the ink layer which is applied from the ink reservoir in the doctor blade chamber to the anilox roller. 
     In early doctor blade systems, which were used with only single or double width printing cylinders, the structure of the doctor blade chamber could be of metal since weight was not a great consideration. The use of metal doctor blade chambers imparted a certain amount of structural rigidity to the doctor blade chamber. Biasing forces could be exerted on the chamber at the ends and would be applied relatively uniformly along the entire lengths of the working and closing doctor blades. 
     Printing presses now in use are characterized by four wide and six wide printing cylinders. The width of such a cylinder is thus four or six times the width of a newspaper page in broadsheet format. The width of the anilox inking roller thus is typically as great as the width of the printing cylinder. This results in the need for a doctor blade chamber that also has the width of up to six newspaper pages in broadsheet format. A traditional metal doctor blade chamber becomes too heavy to be usable. 
     The end seals and the doctor blades of the doctor blade chamber themselves are wear items which periodically must be replaced or refurbished. It is also necessary to periodically remove the doctor blade chamber from its associated mounting assemblies so that it can be cleaned or replaced. The doctor blade assemblies are also periodically thrown off or moved out of contact with the anilox roller so that the roller can be removed from the printing press. All of these requirements of the doctor blade chamber also mean that the weight of the doctor blade chamber needs to be kept at a minimum. 
     One material which has shown itself to be particularly suited for use in the formation of doctor blade chambers is glass fiber reinforced plastic or GRP. Such a material is light in weight and is extremely resistant to chemicals having extreme pH levels. Many currently used printing inks have such high pH levels. While an aluminum or an iron material can be imbued with similar resistance properties, this can be accomplished only through the use of costly and complicated coatings. Such coating are always subject to mechanical damage, such as chipping and scratching. The so-coated aluminum or iron doctor blade chambers are still very heavy and are thus difficult to mount, dismount and handle. 
     GRP doctor blade chamber structures satisfy the need for being light in weight, having durability and being resistant to high pH levels. Their primary limitation is a lack of structural rigidity, when compared with the previously used metal doctor blade chambers. The lack of structural rigidity results in twisting and bending of the doctor blade chamber across the width of the anilox roller. If the chamber flexes, distorts or bends, the two doctor blades do not contact the anilox roller with uniform pressure along the width of the anilox roller. The result of such non-uniform contact force is variance in the ink thickness application to the anilox roller, uneven wear of the doctor blades, premature end seal failures and other undesirable consequences. 
     In an effort to counteract or to compensate for the lack of structural rigidity of the GRP doctor blade chambers, as compared to the prior metal structures, various attempts have been made to rigidify such GRP doctor blade chambers. One prior attempt to overcome this lack of structural rigidity of GRP doctor blade chambers is set forth in EP 1 398 152 A1. In the system disclosed in that document, the doctor blade body is provided with elongated stiffening traction elements that extend parallel to the axis of the anilox roller, in the body of the doctor blade. These traction elements extend beyond the ends of the doctor blade body and are supported by. adjustment sleeves. Those sleeves are secured onto the ends of the traction elements and are actuated to impart a flexural movement to the doctor blade body that is asserted to be substantially equal and opposite to the flexural movement generated on the doctor blade body during the inking of the anilox roller. 
     Another arrangement, as proposed by KBA-Motter, uses a GRP chamber doctor blade that is mounted onto a shaft via plates which are welded to the shaft. That shaft is supported, at its outbound ends by pneumatic or hydraulic cylinders. The force required to adjust the doctor blade chamber is applied by these two cylinders. This is apt to result in a transverse deflection of the supporting shaft and of the doctor blade chamber. As discussed above, such a deflection results in distortion of the GRP doctor blade chamber, a twisting of the blade system and premature wear of the end seals. Another limitation of this prior system is that the working doctor blade is located closer to the axis of rotation of the anilox roller than is the closing doctor blade. The working doctor blade is thus subjected to greater wear and tear than is the closing doctor blade. As a result, more frequent maintenance is apt to be required. 
     It will be apparent that a need exists for a doctor blade system which overcomes the limitations of the prior device. The doctor blade system, in accordance with the present invention, provides such an assembly and system. It is a substantial improvement over the prior systems. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a doctor blade system. 
     Another object of the present invention is to provide a doctor blade system including a doctor blade support. 
     A further object of the present invention is to provide a doctor blade system having a plurality of membrane cylinders distributed over the length of the doctor blade support. 
     Yet another object of the present invention is to provide a doctor blade system usable with a glass fiber reinforced doctor blade chamber. 
     Even a further object of the present invention is to provide a doctor blade system having great structural rigidity. 
     Still yet another object of the present invention is to provide a doctor blade system which facilitates linear adjustment of the doctor blade chamber with uniform load application on both blades. 
     Yet still a further object of the present invention is to provide a doctor blade system which is structured to facilitate exchange of the anilox roller without removal of the doctor blade system from a press assembly. 
     As will be described in greater detail in the description of the preferred embodiment, and as depicted in the accompanying drawings, the doctor blade system, in accordance with the present invention utilizes a lightweight doctor blade chamber that provides an ink chamber defined by spaced working and closing doctor blades and cooperating end seals. The doctor blade chamber is preferably formed using glass fiber reinforced plastic GRP which is of reduced weight and which provides the desired high resistance to chemicals, such as printing inks having high pH levels. 
     The doctor blade chamber is removably mounted to a support plate. That support plate is positioned on linear slides so that it is movable in a direction toward and away from the anilox roller, with which the doctor blade chamber cooperates. The linear slides are secured to pivotable end plates. Quickly releasable blade chamber clamping elements on the support plate provide for efficient yet secure attachment of the chamber doctor blade to the support plate. Detachment of the chamber doctor blade from the support plate is easily accomplished. 
     A box beam is also attached to the pivotable end plates and is essentially parallel to, and spaced from the support plate. The box beam, as its name suggests, has a substantial amount of structural rigidity while still being relatively light in weight. The box beam is provided with a plurality of membrane cylinders that are located in the space between the box beam and the support plate. These membrane cylinders are aligned with the axis of rotation of the anilox roller and are spaced equally along the width of the box beam. Each membrane cylinder is brought into engagement with the support plate to which the doctor blade chamber is mounted. Suitable force is thus exerted, by the plurality of axially spaced membrane cylinders, against the support plate to insure that the doctor blade chamber is brought into proper, uniform engagement with the surface of the anilox roller. Each of the plurality of membrane cylinders can be provided with its own separate source of fluid under pressure, and with its own separate control so that each such membrane cylinder can be individually controlled. This will insure that the working doctor blade, the closing doctor blade and the end seals all are brought into, and remain in proper engagement with the anilox roller. 
     The doctor blade chamber itself does not require a great deal of structural rigidity. It is thus ideally suited to be fabricated using lightweight, chemically resistant materials, such as a glass fiber reinforced plastic or GRP. As a result, the doctor blade chamber, even if it has a length corresponding to that of an anilox roller with which it cooperates, and which is suitable for inking a six wide printing cylinder, is still sufficiently light in weight that it can be routinely handled and manipulated. 
     Attachment of the doctor blade chamber to the support plate is accomplished by the use of spaced blade chamber clamping elements. Since the chamber doctor blade, the support plate and the box beam are all supported by the spaced pivotable end plates, the doctor blade assembly can be pivoted through 90° for routine cleaning or through 120° for doctor blade chamber servicing or removal and replacement. 
     The doctor blade chamber itself does not require the inclusion of reinforcement bars, strips or other rigidifying elements which only serve to increase its overall weight. Instead, the doctor blade chamber relies on the support plate for its support. That support plate, in turn relies on the force imparted to it by the membrane cylinders carried by the box beam to impart to it the appropriate rigidity. Neither the support plate nor the box beams are intended to be routinely removed from the pivotable end plates. The support plate is supported on those end plates by linear slides so that it can move, without bending, toward and away from the surface of the anilox roller. Since the membrane cylinders are spaced equidistantly along the box beam and bear against the support plate at a multiplicity of points, the support plate can move along its linear guides to position its supported doctor blade chamber in proper, uniform engagement of the working and closing doctor blades with the surface of the anilox roller. 
     The two pivotable end plates are pivotably connected to exterior plates. Those exterior plates are, in turn, pivotably connected to inner surfaces of side frames of the printing unit. If it is necessary to move the entire doctor blade assembly, such as, for example, to exchange the anilox roller, this can be accomplished by pivoting the exterior plates at their points of attachment to the printing unit side frames. It is not necessary to totally disassemble the doctor blade assembly to allow for exchange of an anilox roller, when such a roller exchange may become necessary. 
     The doctor blade system, in accordance with the present invention, overcomes the limitations of the prior art. It allows the use of a lightweight, chemical resistant doctor blade chamber that can be moved and manipulated. Despite its lightweight and somewhat flexible nature, the doctor blade chamber is provided with structural rigidity by its positioning on its cooperating support plate. That support plate is positioned on linear guides and is movable toward and away from the surface of the anilox roller by the spaced membrane cylinders. The use of the box beam to carry these membrane cylinders insures their rigidity and accomplishes the accurate positioning of the doctor blade chamber in a highly controllable and reproducible manner. 
     The doctor blade system of the present invention overcomes the limitations of the prior art. It is a substantial advance in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and complete understanding of the doctor blade system, in accordance with the present invention, may be had by referring to the description of the preferred embodiment, as is set forth subsequently, and as depicted in the accompanying sheets of drawings, in which: 
         FIG. 1  is a schematic side elevation view of a doctor blade chamber in accordance with the present invention; 
         FIG. 2  is a front perspective view of the doctor blade system in accordance with the present invention and with the anilox roller removed for the sake of clarity; 
         FIG. 3  is a rear perspective view of the doctor blade system of the present invention, again with the anilox roller removed; 
         FIG. 4  is a rear perspective view, similar to  FIG. 3  with the box beam of the doctor blade system removed; 
         FIG. 5  is a perspective view of a portion of the doctor blade system and showing one of the membrane cylinders and the cooperating end plate and exterior plate assembly; 
         FIG. 6  is a schematic depiction of the doctor blade system rotated through 90° in a counter-clockwise direction for routine cleaning; 
         FIG. 7  is a view similar to  FIG. 6  and showing the doctor blade system rotated through 120° in a counter-clockwise direction for doctor blade chamber removal; and 
         FIG. 8  is a view similar to  FIGS. 6 and 7  and showing the doctor blade system rotated 120° in a clockwise direction for ink roller removal. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to  FIG. 1 , and taken in conjunction with  FIG. 2 , there may be seen, generally at  10 , a preferred embodiment of a doctor blade system in accordance with the present invention. It will be understood that doctor blade system, generally at  10 , is intended for use primarily in a flexographic printing system or in other generally well known printing systems. In such systems printing ink is supplied to an ink reservoir  12  in a doctor blade chamber, generally at  14 . That ink is then transferred to the surface  16  of an ink roller, such as an anilox roller  18 . 
     As is well known in the art, a doctor blade chamber, generally at  14  includes a working doctor blade  20  and a closing doctor blade  22  whose outer edges  24 ;  26 , respectively, engage the surface  18  of the anilox roller  18 . Suitable end plates  28  and  30 , as seen more clearly in  FIG. 2  cooperate with the working doctor blade  20  and the closing doctor blade  22  to define the ink reservoir  12 . Seals are placed interiorly of the end plates but are not specifically depicted in  FIG. 2 . Clamping strips  32  and  34  are attached to the doctor blade chamber  14  by clamping bolts  36  to removably attach the two doctor blades to the doctor blade chamber, generally at  14 . 
     Referring again to  FIGS. 1 and 2 , the doctor blade chamber, generally at  14  in accordance with the present invention, is preferably fabricated of a lightweight material that is highly resistant to chemicals with extreme pH levels. Glass fiber reinforced plastic or GRP is one such suitable material. While other materials are also suitable for use in the fabrication of the doctor blade chamber, generally at  14 , GRP has been shown to be one particularly suitable material. Doctor blade chamber  14  includes a rear wall  40 , an upper wall  42  and a lower wall  44 , all as seen in  FIG. 1 . A pair of spaced doctor blade chamber handles  46  and  48  are spaced along the upper wall  42  of the doctor blade chamber  14 . End plates  28  and  30 , as discussed above, in cooperation with suitable end seals (not shown), complete the overall structure of the doctor blade chamber generally at  14 . 
     While not specifically shown in  FIG. 1 , it will be understood that the doctor blade chamber  14  includes ink inlet and outlet fittings, which will be discussed in detail subsequently. The purpose of these ink inlet and outlet fittings is to allow the circulation of printing ink through the ink reservoir or ink chamber  12 . It is from that ink flow that the ink is provided to the ink reservoir  12  and ultimately to the surface  16  of ink roller  18 . The engagement of the edges  24  and  26  of the working and closing doctor blades  20  and  22 , respectively is the mechanism by which the amount of ink transferred from the ink reservoir  14  to the ink roller surface  16  is controlled. 
     Referring now to  FIGS. 2 and 4 , the doctor blade chamber  14  is securable to a full length support plate, generally at  50 . Support plate  50  is a generally rectangular metal plate or beam that includes a generally planar central web  52 , which is oriented generally vertically in the use position of the doctor blade system, generally at  10 , as seen in  FIGS. 1-4 . Support plate, generally at  50 , has a height generally equivalent to a height “h” of the rear wall  40  of the doctor blade chamber  14 . A length “l” of the support plate  50  is greater than a cooperating length of the chamber doctor blade  14 . A mounting flange  54  or  56  is secured at either end of the central web  52  of the support plate  50 . Each such mounting flange  54  or  56  is generally perpendicular to the plane of the central web  52  of the support plate  50 . The flanges  54  and  56  are used to attach the support plate  50  to spaced pivotable end plates, generally at  58  and  60  as will be discussed shortly. 
     The doctor blade chamber  14  is removably attachable to the support plate  50  and specifically to the central web of the support plate. To accomplish this releasable attachment, the rear wall  40  of the doctor blade chamber  14  is provided with spaced mounting studs  62 , which are shown generally schematically in  FIG. 1 . Each such mounting stud includes a mounting stud shank  64  and an enlarged mounting stud head  66 . Each such stud  62  may extend through the body of the doctor blade chamber  14  and could be secured by a suitable recessed retaining nut  68 , as seen in  FIG. 1 . Other types of cooperative securement of the mounting studs  62  in the body of the doctor blade chamber  14  are also within the scope of the present invention. 
     The support plate central web  52  is provided with a plurality of somewhat ovoid or elongated through bores, which are not visible in the several drawings. These through bores, whose long axes extend vertically in the orientation of the support plate  50  shown in  FIG. 4 , are cooperatively spaced to receive the mounting studs  62  which are positioned on the rear wall  40  of the doctor blade chamber body. The shanks  64  of the mounting studs  62  are of an appropriate length which is slightly greater than a thickness of the central web  52  of the support plate  50 . In this way, the stud heads  66  have inner surfaces  70  which will be spaced from a rear surface  72  of the central web  52  of the support plate when the rear wall  40  of the doctor blade chamber is in abutment with a front surface  74  of the central web  52  of the support plate  50 . 
     Referring now to  FIG. 4 , there are provided a number of spaced doctor blade chamber locking lever assemblies, each generally at  80 . Each such doctor blade chamber locking lever.  80  assembly includes an upper end with a gripping flange  82 , a central body with an elongated slot  84  and a bifurcated lower wedging fork  86 . A clamping screw  88  extends through each of the elongated slots  84  and has an enlarged gripper head  90 . The wedging fork  86  has two spaced tines  92  which are sized to accept the shank  64  of the mounting stud  62  between them. The tines each have interior wedging surfaces that are engagable with the inner face  70  of the mounting stud when the locking lever is slid down so that the mounting studs  62  are positioned between the spaced tines  92  of each cooperatively located locking lever  80 . 
     With the doctor blade system  10  rotated generally 120° in a counter-clockwise direction, in respect to the position shown in  FIGS. 1-4 , in a manner which will be discussed in detail shortly and which is depicted schematically in  FIG. 7 , the doctor blade chamber  14  is securable on, or removable from the support plate  50 . Assuming that there is no doctor blade chamber  14  currently supported on the support plate  50 , one can be brought into position and can be placed on the support plate central web  52 . This is done by aligning the doctor blade chamber mounting studs  62  with the respective, somewhat elongated, mounting holes in the support plate  50 , which holes are not specifically shown. The doctor blade chamber handles  46  and  48  can be used to help position the doctor blade chamber  14  on the support plate  50  so that the rear wall  40  of the doctor blade chamber is in engagement with the front surface  74  of the central web  52  of support plate  50 . At this point, the locking lever assemblies  80  will be slid to their locking positions where the inner wedging surfaces  94  of tines  92  will engage the inner surface  70  of each cooperative one of the mounting studs  60 . The support plate  60  can then be rotated back into a position where the central web  52  is generally vertical. 
     It is essential that the working doctor blade  24  and the closing doctor blade  26  be spaced equidistant from the axis of rotation of the anilox or inking roller  18 . As may be seen in  FIG. 4 , the central web  52  of the support plate  50  is provided with at least two vertical stops  100 , each one of which underlies one of the doctor blade chamber mounting studs  62 . Each such vertical stop  100  includes a stop base  102  and a vertically adjustable stop pedestal  104 . Each such stop pedestal  104  includes a stop head  106  which supports the stud head  66  of its respective one of the doctor blade chamber mounting studs  60 . By vertical adjustment of the stop pedestals  104 , the position of the doctor blade chamber  14  can be properly set so that the working doctor blade  20  and the closing doctor blade  22  are equidistant from the anilox roller axis of rotation. The positioning of these vertical stop pedestals is typically done by the factory and is not typically the subject of field adjustment. 
     Once the inner wedging surfaces  94  of the tines  92  of the locking levers  80  have been brought into firm engagement with the inner surfaces  70  of the mounting sheet heads  66 , by firm downward pressure exerted on the locking lever gripping flanges  82 , the gripper heads  90  of the clamping screws  88  can be used to clamp the locking levers  80  in place. This provides for positive securement of the doctor blade chamber  14  on the support plate  50 . Removal of the doctor blade chamber  14  from the support plate  50  is accomplished by reversal of this procedure. 
     The support plate  50  is supported, at each of its ends, in a linear slide assembly, generally at  110 , as may be seen in  FIGS. 2 ,  4  and  5 . Referring initially to  FIG. 5 , the linear slide assembly includes a slide rail  112  which is attached to each inner face  114  of its respective pivotable end plate  58  or  60 . The slide rail  112  is dimensioned to receive, and to support, a cooperatively shaped slide block  116 . The slide rail  112  and the slide block  116  are formed with a cooperating tongue and groove construction, or its structural and functional equivalent, so that the slide block  116  can move toward and away from the anilox roller  18  but cannot shift axially with respect to the anilox roller  18 . If desired, the slide rail  112  and the slide block  116  could include suitable linear bearings to insure essentially friction free movement of each slide block  116  along its cooperating slide rail  112 . It would also be possible to reverse the relative positions of the slide rail  112  and the slide block  116 . 
     A support plate mounting flange securement bracket  120  is attached to each one of the linear slide blocks  116 , again as may be seen most clearly in  FIG. 5 . Each of these securement brackets  120  includes a mounting channel  122  and a mounting plate  124 . The mounting channel  122  is sized to be positionable over the slide block  116  and can be secured to it by welding or the like. The mounting plate  124  is generally planar and has a plurality of threaded bores  126 , each of which is adapted to receive a cooperating bolt  128 . As may be seen more clearly in  FIG. 2 , the mounting flanges  54  and  56  of the support plate  50  have their own bores, which are alignable with the threaded bores  126  on the mounting plates  124  of the support plate mounting flange securement bracket  120 . The securement bolts  128  will pass through these bores in the mounting flanges  54  and  56 , will be received in the threaded bores  126  of the mounting plates  124  and will thus positively connect the support plate  50  to the two pivotable end plates  58  and  60 . The support plate  50  is thus securely, yet removably connected to its respective linear slide assemblies, generally at  110 . 
     Turning now to  FIG. 3 , there may be seen a box beam assembly, generally at  130  which is also attached to the two spaced pivotable end plates  58  and  60 . The box beam  130  is, as its name implies, a hollow structural member, preferably of metal, such as steel, and having a great amount of structural rigidity. A box beam  130  of this general construction thus provides its requisite structural rigidity while keeping its weight to a minimum. Each end of the box beam  130  is provided with its own mounting ears  132 . These mounting ears  132  are provided with through bores that receive box beam mounting bolts  134 . The bolts  134  are receivable in threaded bores  136  which are cooperatively formed in the end plates  58  and  60 , as may be seen in  FIGS. 3 and 5 . Each end of the box beam  130  has both upper and lower mounting ears  132 , as is shown most clearly in  FIG. 5 . The result is that the box beam  130  is very rigidly secured to the two pivotable end plates  58  and  60 . While box beam  130  is depicted as a generally hollow, rectangular structural member, it will be understood that this is exemplary of a number of geometrical shapes which could be utilized to provide the requisite structural rigidity, while keeping the overall weight relatively low. 
     A plurality of membrane cylinders, generally at  140  are attached to a front face  142  of the box beam  130  by suitable fasteners  144 . These membrane cylinder fasteners  144  are seen more clearly in  FIG. 4  in which the box beam  130  has been omitted. These membrane cylinder fasteners  144  are also seen in dashed lines in  FIG. 5  because they are within the confines of the interior of the hollow box beam  130 . Suitable access plates  146  are attached to a rear face  148  of the box beam and cover access ports that provide access to the membrane cylinder fasteners  144  in case one of the membrane cylinders  144  has to be removed from the box beam  130 . 
     The front face  142  of the box beam  130  is spaced rearwardly from the rear surface  72  of the support plate  50 . The membrane cylinders  140  are sized to fit into the resultant space, which is seen most clearly in  FIG. 3 . Each of the membrane cylinders includes a cylinder body  150  and a cylinder plunger  152 . Each such plunger  152  has a plunger face  154  that is engagable with the rear surface  72  of the support plate  50 . As may be seen in  FIG. 4 , there are four such membrane cylinders  140  situated along the length of the box beam  130 . That specific number of membrane cylinders  140  is only for purposes of illustration. The specific number of such membrane cylinders  140  will depend on the length of the box beam  130 . It will be understood that these membrane cylinders  140  will be spaced equally along the box beam  130  and will be out of alignment, in an axial direction of the anilox roller  18 , with the doctor blade chamber locking lever assemblies  80 . Both the number of those locking levers  80  and the number of membrane cylinders  140  can be varied as a function of the length of the doctor blade chamber  14 . 
     Each membrane cylinder  140  will be connected to a supply of fluid under pressure. Such fluid, such as compressed air, is readily available in a printing plant. The specific compressed air lines are not specifically depicted in the drawing figures for clarity of illustration. It will be understood that a suitable control assembly would be available to control the flow of compressed air to the membrane cylinders. While membrane cylinders  140  have been depicted and described in this preferred embodiment, it will be understood that other suitable force applying assemblies, such as linear actuators, piezo-electric devices, and the like could be substituted for the described and depicted membrane cylinders  140 , whose function is to provide an equally distributed forward acting biasing force against the support plate  50 . 
     The membrane cylinders  140  are aligned on the box beam  130 , and the box beam is situated, with respect to the support plate  50 , so that the points of engagement of the membrane cylinder plunger faces  154  will be in alignment with each other and equally as importantly will be aligned with the axis of rotation of the anilox roller. When the membrane cylinders are charged with the requisite amount of compressed air, the plunger faces will push against the rear surface  72  of the support plate  50  with sufficient force to move the support plate  50  forwardly along the linear slide assemblies  110  toward the anilox roller  18 . The use of the two linear slide assemblies  110  assures that the support plate  50  will move toward the anilox roller  18  in a smooth linear manner. By controlling the pressure of fluid that is being supplied to the membrane cylinders  140 , the force which the doctor blade edges  24  and  26  will exert against the surface  16  of the anilox roller  18  will be carefully controlled. Because there are a plurality of the membrane cylinders  140  spaced along the box beam  130 , and due to the rigidity of that box beam  130 , a controllable, certain force can be applied to the support plate  50  and thus to the surface  16  of the anilox roller  18  by the working doctor blade and closing doctor blade edges  24  and  26 . In a similar manner, the seals, which are held in place by the end plates  28  and  30 , are also engaged against the anilox roller with a positive, controllable force. The two desired goals of a lightweight doctor blade chamber and a structurally rigid doctor blade mount are thus provided by the doctor blade system of the present invention. 
     As mentioned previously, the doctor blade chamber  14 , the support plate  50  and the box beam  130  are all attached to a pair of pivotable end plates  58  and  60 . As may be seen in  FIG. 5 , this attachment is accomplished by the use of an inner pivot shaft  160  that extends between each end plate  58 ,  60  and its respective adjacent one of a pair of exterior plates  162  and  164 . Those exterior plates  162  and  164  are, in turn, pivotably supported, by outer pivot shafts  166  to inner wall surfaces of the printing press side frames, one of which is shown schematically in  FIG. 5 . The inner end plates  58  and  60  are pivotable to move the doctor blade chamber either through generally 90° in a counter-clockwise direction with respect to the position shown in  FIG. 3 , and as seen in  FIG. 6 , to a first thrown-off position for maintenance of the doctor blade chamber and the doctor blades, or further to a second thrown-off position displaced by 120° in a counter-clockwise direction, as shown in  FIG. 7 , and again with respect to the position shown in  FIG. 3 , for removal of the doctor blade chamber  14  from its attachment to the support plate  50 . The exterior plates  162  and  164  can be pivoted about their respective outer pivot shafts  166  through generally about 120° in a clockwise direction, with respect to their position seen in  FIG. 3 , to a doctor blade system thrown-off position, as seen in  FIG. 8 , in which the anilox roller  18  can be removed from the printing press. 
     Each of the two spaced end plates  58  and  60  has an upper fin  168 ,  170  respectively, as may be seen in  FIGS. 2-5 . As may be seen most clearly in  FIG. 5 , each one of these end plate upper fins  168 ,  170  is provided with a tension rod receiving channel  172 . Each such tension rod receiving channel  172  is sized to receive a cooperating tension rod  174 . An inboard end of each such tension rod  172  is attached to a respective adjacent exterior plate  162 , 164  by a swivel coupling  176 . An outboard end of each tension rod  174  is provided with a tension lever  178 . Each such tension lever  178  includes a cam plate  180 . That cam plate  180  is brought into engagement with a rear surface  182  of the respective end plate upper fin  168 ,  170 . In use, the tension lever  178  can be rotated by approximately 180°-270° to engage or disengage the cam plate  180  with the fin rear surface  182 . That engagement or disengagement will either hold the tension rod  174  in the tension rod receiving channel  172 , to thereby retain the doctor blade assembly in it operational position, or will allow movement of the tension rod  174  out of the cooperating receiving channel  172 . In that disengagement position, the two end plates  58  and  60  can be pivoted, about their inner pivot shafts  160 , with respect to the exterior plates  162  and  164 , respectively, that support them. 
     As was asserted previously, the end plates  58 ;  60  are pivotable, with respect to their associated exterior plates  162 ;  164  through either 90° or 120°, both in a counter-clockwise direction, as seen in  FIGS. 6 and 7 . The 90° rotation is used to facilitate the checking of the doctor blade chamber  14  and the associated doctor blades and end plates and seals. The 120° rotation is typically utilized when the doctor blade chamber  14  is to be removed from its associated support p late  50 , in the manner described previously. As may be seen in each of  FIGS. 2-4 , each exterior plate  162 ,  164  is provided with an arcuate guide slot  184 ,  186 . An index pin  188  is carried in each of the two end plates  58 ;  60 . Each such index pin  188  includes an index pin shank  190  and an index pin actuating handle  192 . Each of the two exterior plates has a lower blind bore  194  or an upper bore  196 . 
     In the use position of the doctor blade chamber  14 , the pin shank  190  of each index pin  188  is received in its associated one of the exterior plate blind bores  194 . When it is necessary to rotate the doctor blade chamber  14  counter-clockwise through 90°, the tension rods  174  are released by rotation of the tension levers  178  and the tension rods  174  are pivoted up and out of their respective channels  172  about their respective swivel couplers  176 . The tension rods can be held in their elevated positions by suitable biasing springs, which are not specifically shown, that are incorporated into the swivel couplings  176 . Once the tension rods have been disengaged, the index pins  188  can be moved inwardly to disengage them from their blind bores  194  in the exterior plates  162 ;  164 . The doctor blade chamber handles  48  and  46 , and similar box beam handles  198 ,  200  can be manually engaged and the doctor blade chamber  14 , support plate  50 , box beam  130  and end plates  58  and  60  can be pivoted through 90° in a counter-clockwise direction. The index pins  188  can be reinserted into the slots  184  to limit the rotation to 90°, as shown schematically in  FIG. 6 . Alternatively, the index pins  188  can be inserted into the bores  196  located above the arcuate slots  184  to secure the now-rotated assembly at its 120° rotation position, as depicted schematically in  FIG. 7 . 
     In certain instances, such as when it is necessary to remove the anilox or similar ink roller  18 , it is appropriate to rotate the entire doctor blade system through an upward rotation, in a clockwise direction, with respect to its position as depicted in  FIGS. 2-4 . This is accomplished by first rotating the end plates  58 ;  60  through their 120° positioned displacement, as discussed above, with respect to the exterior plates  162 ;  164 . Once this has been accomplished, the exterior plates can themselves be rotated in a clockwise direction, with respect to their positions shown in  FIGS. 2-5 , about their respective outer pivot shafts  166  into the position depicted in  FIG. 8 . 
     As may be seen most clearly in  FIG. 5 , a base stop block  202  is secured to inner surfaces of the printing press side frame, as is shown schematically in  FIG. 5 . This base stop block  202  supports a tension screw  204  having a first, inboard end  206  that is received by a swivel mount  208  in the base stop block. A shank  210  of the tension screw  204  is received in a channel  212  in the lower edge of each exterior plate. A tension screw nut  214  is provided at an outboard end of the tension screw  204 . Once the tension screw nut  214  has been backed off, the shank  210  of the tension screw  204  will drop out of the exterior plate channel  212 . This will allow the exterior plates to pivot with respect to the side frames of the printing press, generally in a clockwise position, as seen in  FIG. 8 . 
     The base stop block  202  carries a first base stop  216 . This first base stop  216  has an enlarged base stop head  218 . The base stop head  218  is engagable with an exterior plate stop body  220 . The exterior plate stop body  220  is secured to each one of its respective exterior plates by suitable set screws  222 . Each of these exterior plate stop blocks  220  is provided with an upwardly extending end plate base stop member  224 . That end plate base stop member  224  is provided with an enlarged end plate stop head  226  which engages a stop abutment  228  on the lower surface of each end plate  58 ;  60 . As was the case with the vertical stops, generally at  100 , these base stops  216  and  220  are adjusted and are secured in place during assembly of the doctor blade system, typically by factory personnel. They are not intended for adjustment in the field by the press operator. 
     Turning again briefly to  FIG. 3 , it will be seen that the doctor blade chamber, generally at  14  is provided with suitable quick disconnect ink hose connections  230  and  232 . These are generally known in the art and need not be discussed in detail. They are used to connect the doctor blade chamber to an ink supply hose or line, at one end of the doctor blade chamber, and to a suitable ink return hose or line at the other end of the doctor blade chamber. Ink is thus caused to flow through the ink reservoir  12  in the axial direction of the ink roller  18 . 
     The doctor blade system, in accordance with the present invention is a substantial improvement over prior systems. In a large printing press system such as one producing upwards of 2-2.5 million copies a day, prior doctor blade systems would require seal and blade replacements or adjustments every three to four weeks. The flexibility of the doctor blade chambers caused ink density variations, which led to print quality problems. These prior systems had high maintenance requirements and low operational stability. 
     In marked contrast, the doctor blade system in accordance with the present invention, has a seal life of up to 12 weeks. The structural rigidity that is provided by the overall system has greatly improved color density conformity. It is much easier for press personnel to change doctor blades and seals and to maintain the system. The present system can be adapted to existing press structure without particularly great changeover expenses. 
     While a preferred embodiment of a doctor blade system, in accordance with the present invention, has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes, for example, in the specific structure of the ink roller, the drive for the ink roller, the supply of the printing ink and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.