Abstract:
A doctor blade holder is disclosed that includes a first member, a second member position adjustment elements, and fluid assisted cleaning elements. The first member includes an elongated edge that is adapted for receiving a doctor blade, and the second member is movably coupled to the first member. The second member is secured to a doctor back. The position adjustment elements are for adjusting the relative position of the first member and the second member. The fluid assisted cleaning elements are for providing pressurized fluid to an area near an elongated edge of the doctor blade. The fluid assisted cleaning elements include at least one plenum within the first member.

Description:
PRIORITY 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 61/032,099 filed Feb. 28, 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to doctor blade holders, and is concerned in particular with an improved design that facilitates holder sheet shedding, and water or debris removal performance while maintaining desired doctor blade holder performance. 
         [0004]    2. Description of the Prior Art 
         [0005]    Many roll cleaning and sheet shedding applications on paper machines and other web handling applications involve blade support devices commonly referred to as doctor blade holders. Typically, a doctor blade holder is mounted on a doctorback which is a heavy-duty beam that spans the paper machine width. The rear portion of a doctor blade is received into the holder which supports the blade in a pre-determined position relative to a surface to be cleaned. The holder works in concert with the doctoring assembly to apply the working edge of the blade, found on the blade&#39;s front portion, to an adjacent moving surface. 
         [0006]    U.S. Pat. No. 6,491,791 discloses a method and apparatus to clean roll surfaces or fabrics used in papermaking machines, wherein a doctoring element (4) includes one or two integral doctor blades (9, 9A) as well as an integral gas chamber (50) that provides pressurized gas, e.g., compressed air, to the outgoing side of a doctoring apparatus having one doctor blade (9), and to the inter-blade area of a doctoring apparatus having two doctor blades (9, 9A). The compressed air is provided to enhance the water or dirt removal capabilities. Each of the disclosed apparatus involves doctor blades that are integral with the structure forming the gas chamber within the doctoring element. The example of a two blade doctoring element, for example, provides that the interblade space forms a closely and tightly delineated pocket into which compressed air may be passed (col. 3, lines 18-20). The high pressure compressed air in an example, escapes under the doctor blades via grooves on the grooved-shell roll being processed (col. 6, lines 59-63). The use of such integral doctor blades requires that the entire doctoring element be replaced whenever the doctor blades become too worn. The doctoring apparatus are also not disclosed to be position adjustable with respect to the roll, and it is not at all clear how such an integral gas chamber may be incorporated in a doctoring apparatus that provides adjustable position accuracy with respect to a roll as well as flexibility in doctoring a roll along an elongated length of the doctor blade. 
         [0007]    U.S. Pat. No. 6,139,638 discloses a doctor blade holder apparatus that includes a planar upper holding member that is pivotally mounted to a tray such that the position of the upper holding member (34) with respect to the tray (26) may be adjusted by unloading and loading tubes (30, 32). The upper holding member (34) also includes a plurality of distribution passages (60) that are coupled respectively off of the upper holding member (34) via a plurality of branch conduits (62) to a common header (64). The apparatus requires therefore, that the plurality of branch conduits (62) be provided along the elongated length of the holding member (34), which adds to manufacturing costs and complexity. Moreover, the pressurized fluid must maintain sufficiently equalized pressure as it travels through the separate conduits (62) as the fluid is directed toward the roll along the elongated length of the doctor blade. 
         [0008]    There remains a need, therefore, for a doctor blade holder system that facilitates consistent debris removal without limiting the flexibility of the doctor blade holder system or the effectiveness of the doctoring process. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to provide a doctor blade holder specifically designed to apply pressurized fluid to assist in the detachment of a paper web from a roll surface and convey the web away from the roll. 
         [0010]    Another object is to integrate the one or more fluid delivery systems into the holder body in a manner that serves the design intent of a well managed web exit from its detaching point. 
         [0011]    Another object is to integrate within the same holder body additional pressurized fluid delivery means and directing said fluid to the area near the blade-roll contact line in order to remove debris that is known to accumulate there. 
         [0012]    Another object is to provide within the holder body fluid jets designed to evacuate the water or debris dislodged from the cleaned surface. 
         [0013]    Another object is to provide doctor blade holders that provides for effective fluid delivery onto the doctor blade yet also facilitates the replacement of worn doctor blades. 
         [0014]    Another object is to provide within the holder design a two-tube blade loading and unloading system familiar to paper machine operators and easily integrated with pre-existing equipment. 
         [0015]    Another object is to incorporate groups of one or more holder components into formed pieces via extrusion processes thereby reducing assembly part counts and associated labor, as compared to the multiple part assembly processes of certain prior art holders. 
         [0016]    Another object is to provide additional cross-machine flexibility by sectioning the rotating portion of a full-length holder into a multiplicity of shorter cross-machine pieces that may be assembled individually and/or together with the doctor base piece to form a segmented full-length holder assembly. 
         [0017]    The invention provides a doctor blade holder that includes a first member, a second member position adjustment elements, and fluid assisted cleaning elements. In accordance with an embodiment, the first member includes an elongated edge that is adapted for receiving a doctor blade, and the second member is movably coupled to the first member. The second member is secured to a doctor back. The position adjustment elements are for adjusting the relative position of the first member and the second member. The fluid assisted cleaning elements are for providing pressurized fluid to an area near an elongated edge of the doctor blade. The fluid assisted cleaning elements include at least one plenum within the first member. 
         [0018]    In accordance with another embodiment, the first member includes an elongated edge that is adapted for receiving a doctor blade, and the second member is movably coupled to the first member by pivotal coupling structure that includes at least a portion thereof that is integrally formed with the first member. The second member is secured to a doctor back. The position adjustment elements are for adjusting the relative position of the first member and the second member. The position adjustment means includes a portion that is secured to the first member by mounting structure that is integrally formed with the first member. The fluid assisted cleaning elements are for providing a first pressurized fluid to a leading edge side of an elongated edge of the doctor blade. The fluid assisted cleaning elements include a first plenum within the first member. 
         [0019]    In accordance with a further embodiment, the first member includes an elongated edge that is adapted for receiving a doctor blade. The second member is movably coupled to the first member and is also secured to a doctor back. The position adjustment elements are for adjusting the relative position of the first member and the second member. The position adjustment elements include at least one fluid expandable reservoir that causes the relative position of the first and second members to be changed when fluid is introduced into the fluid expandable reservoir. The fluid assisted cleaning elements are for directing a first pressurized fluid onto a leading edge side of an elongated edge of the doctor blade. The fluid assisted cleaning elements include a first plenum within the first member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The following description may be further understood with reference to the accompanying drawings in which: 
           [0021]      FIG. 1  is an illustrative diagrammatic side view of a doctor blade holder in accordance with an embodiment of the present invention attached to a doctorback; 
           [0022]      FIG. 2  is an illustrative diagrammatic enlarged side view of the doctor blade holder of  FIG. 1 ; 
           [0023]      FIG. 3  is an illustrative diagrammatic isometric view from above of a portion of the doctor blade holder of  FIG. 1 ; 
           [0024]      FIG. 4  is an illustrative diagrammatic cross-sectional view of the doctor blade holder of  FIG. 3  taken along line  4 - 4  thereof; 
           [0025]      FIG. 5  is an illustrative diagrammatic exploded isometric view from below of the doctor blade holder of  FIG. 1 ; 
           [0026]      FIG. 6  is an illustrative diagrammatic sectional view of an enlarged portion of the doctor blade holder of  FIG. 5 ; 
           [0027]      FIG. 7  is an illustrative diagrammatic isometric view from above of a doctor blade holder in accordance with an embodiment of the invention shown without the doctor blade and cover elements; 
           [0028]      FIG. 8  is an illustrative diagrammatic isometric view from above of the doctor blade holder of  FIG. 7  including the doctor blade and a plurality of cover elements. 
           [0029]      FIG. 9  is an illustrative diagrammatic cross-sectional view of a doctor blade holder of another embodiment of the invention similar to the view shown in  FIG. 4  of the first embodiment; and 
           [0030]      FIG. 10  is an illustrative diagrammatic sectional view of an enlarged portion of the doctor blade holder of  FIG. 9 ; 
       
    
    
       [0031]    The drawings are shown for illustrative purposes only. 
       DETAILED DESCRIPTION 
       [0032]    The present invention incorporates one or more fluid supply plenums for piping fluid into the body of the holder. The supply piping system distributes pressurized fluid to one or more nozzles arrayed along the holder in an elongated direction. The pressurized fluids may be used to assist the doctor blade holder in the detachment of a paper web from a roll surface; to shower the doctor blade generally, or particularly in the area near the blade-to-surface contact line; or to dislodge water or debris from process surfaces such as grooved or drilled rolls. 
         [0033]    As shown in  FIGS. 1 and 2 , a doctoring apparatus including a doctor blade holder  10  in accordance with an embodiment of the invention includes a first member  12  that is pivotally mounted on a second member  14  such that limited pivotal rotation is permitted with respect to an axis A 1 . As shown in  FIG. 2 , the pivotal rotation is provided by an integrally formed pivotal coupling structure such as continuous rounded male portion  16  on the second member that is received within an integrally formed pivotal coupling structure such as continuous socket portion  18  on the first member. In other embodiments, an integrally formed continuous male portion may be provided on the first member, with an integrally formed continuous socket portion being provided on the second member. The first member  12  receives a doctor blade  30  along an elongated edge of the first member  12 , and the second member  14  is attached to a beam  19  that is attached to a doctor back  20 . The rotational position of the first member with respect to the second member is provided by inflatable loading and unloading reservoirs such as tubes  22 ,  24 . Pivotal rotation of the doctor back  20  is provided by a piston  26  that is coupled to a crank arm  28  to provide rotation of the doctor back  20  with respect to an axis A 2  that is parallel to the axis A 1 . 
         [0034]    As also shown in  FIG. 2 , the first member  12  includes a cap  32  and a body  34 , and the doctor blade  30  is received between a portion of the cap  32  and the body  34 , and may be held in place by an optional spring element  36 . The doctor blade  30  may be readily replaced as desired, for example, when the doctor blade becomes worn, without replacing the entire doctoring apparatus. As a roll  38  rotates about an axis A 3 , the doctor blade  30  is applied to the roll. Plenums  40 ,  42  within the body  34  of the first member  12  are defined by walls that are integrally formed with the first member, and contain pressurized fluid, such as air or water, that are applied to the doctor blade  30  during processing as discussed in more detail below. Each plenum may provide the same fluid or may provide different fluids. The cap  32  and body  34  are joined together using fasteners  44  that are received within apertures  46  in the cap  32  and are secured to the body  34 . 
         [0035]    The first member  12  and second member  14  are formed preferably by extrusion or pultrusion, from metal, such as stainless steel alloys such as 300 series, or aluminum alloys such as series 6000. Aluminum alloys are preferably treated with one or more protective coatings well known to those skilled in the art. The cap  21  may alternatively be comprised of a multiplicity of short pieces, extruded or cast from above mentioned alloys, the multiple cap pieces being attached to the rotator  22  is the same manner as for the single, elongated cap. In further embodiments, the members  12 ,  14  may be formed of high temperature resistant polymeric materials or resins, and may include filler material such as fiberglass, ceramic and/or metallic materials. 
         [0036]    With further reference to  FIGS. 3 and 4 , air is provided to the inflatable loading and unloading tubes  22 ,  24  via conduits that may be provided at one or both ends of each of the tubes  22 ,  24 . At least one of the tubes (e.g.,  24  as shown in  FIGS. 2 ,  4  and  5 ) may be mounted to the first member  12  by mounting structure  25  that is integrally formed with the first member  12 . Pressurized fluid, such as compressed air, is provided to the doctoring apparatus via a conduit coupled to the plenum  40 , and another fluid, such as water, is provided under pressure within the plenum  42  via a conduit as well. Each of the plenums  40 ,  42  may be coupled to such conduits at one or both ends of the doctoring apparatus. 
         [0037]    As shown in  FIG. 5 , the compressed air from within the plenum  40  travels out of the plenum  40  and toward the blade  30  via ports  47  that lead to a plurality of passages  48  formed between the cap  32  and a guide plate  50  on the body  34 . The guide plate  50  directs the compressed air onto the leading edge side  52  of the blade  30  as the roll  38  rotates. A flush fastener  54  is employed to secure the guide plate  50  to the body  34 . 
         [0038]    As shown in  FIG. 6 , the fluid under pressure from the plenum  42  (such as water or air) travels out of the plenum  42  and toward the blade  30  via a flood fan nozzle  56 , which as shown in  FIG. 4 , directs the water stream toward the trailing edge side  58  of the blade  30  as the roll  38  rotates. 
         [0039]    As shown in  FIGS. 7 and 8 , multiple caps  32  are provided along the body  34 , in an elongated direction as shown at  60 , and each cap  32  includes a passage that aligns with a port  47  of the continuous plenum  40  in the body  34 . Each cap  32  is secured to the body  34  by fasteners  44  within apertures  46  of the caps  32 . 
         [0040]      FIGS. 9 and 10  show a doctor blade holder  70  in accordance with another embodiment of the invention that includes a first member  72  that is pivotally mounted on a second member  74  such that limited pivotal rotation is permitted with respect to an axis A 4 . The pivotal rotation is provided by an integrally formed pivotal coupling structure such as a continuous rounded male portion  76  on second member that is received within an integrally formed pivotal coupling structure such as a continuous socket portion  78  on the first member. In other embodiments, an integrally formed continuous male portion may be provided on the first member, with an integrally formed continuous socket portion being provided on the second member. The first member  72  receives a doctor blade  90  along an elongated edge of the first member  72 . The rotational position of the first member with respect to the second member is provided by inflatable loading and unloading reservoirs such as tubes  82 ,  84 . The second member is attached to a doctor back as discussed above with reference to  FIG. 1 , and pivotal rotation of a doctor back is provided by a piston that is coupled to a crank arm to provide rotation of the doctor back. 
         [0041]    The first member  72  includes a cap  92  and a body  94 , and the doctor blade  90  is received between a portion of the cap  92  and the body  94 , and may be held in place by an optional spring element  96 . As the roll  38  rotates, the doctor blade  90  is applied to the roll. Plenums  100 ,  102  within the body  94  of the first member  72  are defined by walls that are integrally formed with the first member  72 , and contain pressurized fluid, such as air or water, that are applied to the doctor blade  90  during processing. The cap  92  and body  94  are joined together using fasteners  104 . The first and second members  72 ,  74  are formed as discussed above with reference to  FIGS. 1-8 . 
         [0042]    Air is provided to the inflatable loading and unloading tubes  82 ,  84  via conduits as discussed above. At least one of the tubes (e.g.,  84  as shown in  FIG. 9 ) may be mounted to the first member  72  by mounting structure  85  that is integrally formed with the first member  72 . Pressurized fluid, such as compressed air, is provided to the doctoring apparatus via a conduit coupled to the plenum  100 , and another fluid, such as water, is provided under pressure within the plenum  102  via a conduit as well as also discussed above. Each of the tubes  82 ,  84  and the plenums  100 ,  102  may be coupled to such conduits at one or both ends of the doctoring apparatus. 
         [0043]    The compressed air from within the plenum  100  travels out of the plenum  100  and toward the blade  90  via ports  107  that lead to either a plurality of passages (such as shown at  48  in  FIG. 5 ) or a single elongated passage  108  formed between the cap  92  and a guide plate  110  on the body  94 . The guide plate  110  directs the compressed air onto the leading edge side  112  of the blade  90  as the roll  38  rotates. A combined fastener and flow restrictor  114  is employed to secure the guide plate  11  to the body  94 , as well as to controllably restrict the flow of compressed gas within the passage  108 . 
         [0044]    The water under pressure from the plenum  102  travels out of the plenum  102  and toward the blade  90  via a bidirectional nozzle  116  that via a first opening  120  directs a first water stream toward the trailing edge side  118  of the blade  90  as the roll  38  rotates, and via a second opening  122  directs a second water stream onto the roll  38 . The first and second water streams may be, for example, 90-120 degrees from one another. 
         [0045]    Doctoring assemblies including doctor blade holders of various embodiments of the invention permit the doctor blade to provide the requisite structural and mechanical properties for processing the roll, while also permitting a first fluid to be directed toward a leading edge side of the blade, and permitting a second fluid to be directed toward a trailing edge side of the blade during processing or the roll. 
         [0046]    Those skilled in the art will appreciate that numerous modifications and variations may be made to the above disclosed embodiments without departing from the spirit and scope of the invention.