Patent Abstract:
A method for operably adjusting a forming board lead blade of a paper sheet forming machine of the type having a headbox for impinging a jet of slurry from a slice opening of the headbox onto the surface of a porous wire moving continuously in a horizontal machine direction over the forming board.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     U.S. Pat. Nos.; Ibrahim U.S. Pat. No. 4,684,441, issued Aug. 4, 1987, Ibrahim U.S. Pat. No. 4,718,983, issued Jan. 12, 1988, Miller U.S. Pat. No. 5,421,961, issued Jun. 6, 1995, Mellen U.S. Pat. No. 4,278,497, issued Jul. 14, 1981, and Mellen U.S. Pat. No. 4,280,869, issued Jul. 28, 1981. 
     TECHNICAL FIELD 
     This invention relates to continuous paper sheet forming machines having a Fourdrinier table and more particularly relates to improvements in the forming board of such machines which result in good formation, retention and control of sheet properties. 
     BACKGROUND 
     Prior Art 
       FIG. 1  shows a typical papermaking machine with a Fourdrinier table  37  and the first part of the sheet forming process. This process is typically characterized by the provision of a headbox  21  for directing a jet  23  of papermaking slurry  22 , exiting out of the slice opening of the headbox  21  and impinging on the upper surface of the Fourdrinier table  37  just downstream from the breast roll  27 . Typically a Fourdrinier papermaking machine has a front or tending side and a back or drive side. The tending side is where a wire  26  is pulled off of the Fourdrinier Table  37  when the wire  26  is damaged or worn. The back side of the Fourdrinier is typically where rolls in the fourdrinier are driven. The papermaking slurry  22  is mostly water with solids content or percent consistency of about 1% fiber, fines and fillers. The content of the solids in the water is measured in percent consistency. All of the rolls and table elements of the Fourdrinier Table  37  are supported with cantilever beams such that the wire  26  can be removed like a sock toward the tending side of the machine. 
     The percent consistency on the Fourdrinier table  37  is in the range of from less than 1% at the Headbox  21  to 25% at the end of the Fourdrinier table  37  as water is drained from the slurry  22  along the length of the Fourdrinier. The Fourdrinier table  37  consists of a porous wire mesh or wire  26  moving continuously in the horizontal machine direction  33  on a set of rollers and Fourdrinier table elements that will allow the water to drain through the upper surface of the wire  26  leaving the paper fibers in the slurry  22  to settle on the wire  26  and be removed at the end of the Fourdrinier table  37  at a roller called the Couch Roll not shown in  FIG. 1 . The fiber slurry  22  comes off the Couch Roll as a wet sheet of paper in a continuous unending way as the wire  26  moves back toward the breast roll  27  over wire return rollers  27   a . Two of the Fourdrinier table elements that support the wire  26  are shown in  FIG. 1 , a forming board  30  and a first gravity drainage box  35 . These Fourdrinier table elements facilitate draining of the water through a wire  26  as the slurry  22  progresses along the length of the Fourdrinier  37  resulting in higher solids content or percent consistency in the slurry  22 . The table elements  30  and  35  consist of drainage boxes with a plurality of foil blades that scrape or doctor the water off of the underside of the wire  26  and create pressure pulsations in the slurry  22  above the wire  26  which help keep the fibers in the slurry  22  distributed evenly in the resultant sheet allowing for better sheet quality and strength characteristics. The first of these drainage elements is called the Forming Board  30  which consists of a plurality of foil blades. The first foil of the forming board  30  or lead blade  29  supporting the wire  26  is where a jet flow of the slurry, called the jet  23 , lands or impinges on the wire  26 . 
     Typically the foil blades are mounted on a T-bar assembly, which is familiar to one experienced in the art. The foil blades have a matching groove that fit over the T-bar and provide for sliding the foil blades off of the T-bar on the tending side to replace the blade due to the frictional wear from the wire  26 . Often times this can be done when the machine is in operation. An example of this is in  FIG. 2  where a foil blade called the Follower blade  43  fits over a T-bar  54 . 
     The forming board  30  and particularly the lead blade  29  provide a support surface immediately downstream of the headbox  21 , beneath the wire  26  to gently retain the water in the slurry  22 . The lead blade  29  allows an initial fiber mat to be created on the wire  26  which aids in the retention of fibers, fines and fillers as water is removed down the Fourdrinier table  37 . The lead blade  29  is made of composite materials with the exposed surface to the wire  26  made of a hard ceramic cover  9   b  shown in  FIG. 5 a    to resist wear with the moving wire  26  over the forming board  30 . The core of the lead blade  29  is usually a composite material such as fiberglass and provides for a surface to adhere the ceramic material forming a continuous blade that is equal in length to the width of the Fourdrinier Table  37 . 
     The correct landing of the jet  23  onto the wire  26  is essential to good formation, retention, and control of sheet properties. This is published in trade journals one of which is referenced (The Institute of Paper Chemistry “IPC” Technical Paper #206 “Fourdrinier Jet Geometry”). The referenced paper states that the location of the forming board  30  is especially critical as shown in  FIG. 2  where the leading edge of the forming board lead blade  29  should split the jet  23  in a particular manner so that any “jump” or “bounce” on the Forming Board  30  is eliminated. This particular manor of the split of the jet  23  will result in a downward jet  28  causing a momentum change in the remaining part of slurry  22  to travel with the wire  26  horizontally in the machine direction  33 . 
     The top and bottom slice lips ( 4  &amp;  5 ) of the headbox  21  serve to regulate the size and shape of the jet  23 . This is affected by the I/b ratio where I in  FIG. 2  is the distance the bottom slice Lip  25  extends over the top slice lip  24  and b is the opening height of the top lip  24  above the bottom lip  25  which extends across the full width of the headbox  21 . The opening of the slice determines the flow rate of the slurry  22  out of the headbox  21 . Additionally, the pressure inside the headbox  21  provides the initial velocity out of the jet  23  emerging out of the slice opening of the headbox  21  to allow for the speed of the jet  23  to impinge on the wire  26  at the correct velocity in relation to the speed of the wire  26 . The velocity of the jet  23  can be faster than the wire  26 , as in the case of velocity forming, the same speed of the wire  26  or slower than the wire  26  such as in the case of pressure forming depending on the grade of paper being produced. For this reason the location of impingement of the jet  23  on the wire  26  and the downward direction  32  of the jet  23  (which can be controlled by the I/b ratio) impinging on the wire  26  from the headbox  21  will be different for each grade of paper being produced. Generally the profile and the location of impingement on the wire  26  can be calculated based on the influence of gravity and the basic laws of hydraulics for which is commonly treated in technical literature. However the ideal location of the forming board  30  can depend on many factors other than jet and wire velocity such as air entrapment, the shape of the leading edge of the lead blade  29 , including but not limited to the angle “Y” shown in  FIG. 5 a   , and sheet properties that are to be obtained. Hence, the art of papermaking and the ideal position of the forming board  30  being dependent on the choices made by the operator. 
     Unfortunately most machines do not provide for the headbox  21  to move to allow for the jet  23  to impinge on the wire  26  in the same place or at the same direction  32  as shown in  FIG. 2  for all grades. For this reason prior art has concentrated on moving the forming Board  30  as does this invention. 
     Prior art in U.S. Pat. Nos.; Ibrahim U.S. Pat. No. 4,684,441, issued Aug. 4, 1987, Ibrahim U.S. Pat. No. 4,718,983, issued Jan. 12, 1988, and Miller U.S. Pat. No. 5,421,961, issued Jun. 6, 1995 provide for the movement of the forming board in the machine direction toward the headbox or away from the headbox. This invention is an improvement on the above described prior art by only moving the lead blade and not the whole forming board assembly as described in the aforementioned Patents. 
     Additionally, this invention is not concerned with the trailing edge of the lead blade for which the Ibrahim Patent describes because if the leading edge of the lead Blade  29  is properly located to split the jet  23  as shown in  FIG. 2  such that the horizontal momentum of the slurry  22  would reduce the impact of where the trailing edge of the lead blade  29  is located. In  FIG. 2  the jet  23  impinges at the leading edge of the lead blade  29  in the direction of  32 . The velocity of the slurry  22  should be purely horizontal in direction  33  with a thickness of t 2  and the downward pointing jet  28  in direction  31  with a thickness of t 3  such that t=t 2 +t 3 . The ratio t 3 /t 2  should be in the range of 5% to 10% to provide for the ideal momentum transfer depending on several factors including the shape of the leading edge of the Lead Blade  29  including the angle “Y” shown in  FIG. 5   a.    
     Another improvement of prior art is the simplicity of how the lead blade  29  is moved in the machine direction  33   a , toward or  33   b , away from the headbox  21  shown in  FIGS. 3 and 3   a . This invention includes a simple angular slide arrangement similar to prior art in U.S. Pat. Nos.; Mellen U.S. Pat. No. 4,278,497, issued Jul. 14, 1981 and Mellen U.S. Pat. No. 4,280,869, issued Jul. 28, 1981 that can be actuated outside of the width of the Fourdrinier table  37  using a jack screw actuator  36  to move the Lead Blade  29 .  FIGS. 10, 10   a , and  11  show another embodiment of the invention whereby the lead blade  29  is moved along the angular slides by a plurality of servo gear-motor drives  68  with a rack and pinion design. The novel concept of the angular slide in this invention will be more fully realized and understood from the following detailed description when taken with the accompanying drawings. The simplicity of these designs eliminates the need for cylinders, jack screws and cross machine shafts as shown in prior art of U.S. Pat. Nos. 4,684,441, 4,718,983, and 5,421,961 that would be installed across the width of the Fourdrinier table with more exposed to the drainage of the slurry under the wire and which are more unreliable and increase the cost of manufacture of the Forming Board. 
     This invention is an improvement in the angular slide arrangement as mentioned above in U.S. Pat. No. 4,278,497 in that the wear strip or blade that slides back and forth along a single T-bar the full width of the machine has too shallow of an oblique angle requiring a much too long blade to move along the cross machine direction to allow the required movement of the blade in the machine direction. By having a plurality of grooves across the full width of the blade, not shown in prior art, this invention allows for a steeper angle resulting in a shorter blade and more movement of the blade in the machine direction. This is of course at the expense of increased loading on the actuator that moves the blade. Additionally, the actuator providing the force in prior art is not pulling in the same direction as the oblique angle of the slide requiring additional linkage and pin connections to move the blade at additional cost to manufacture the equipment. The novelty of the arrangement of the grooves and T-bars for which the blade slides on in this invention is illustrated in  FIGS. 3 and 3   a  where the oblique angle “X” is large enough to allow for the required movement of the blade in the direction  33   b  in  FIG. 3 a    or the direction  33   b  in  FIG. 3  and provide for a blade that is not so long and impractical to be installed in the machine. This is accomplished by having a plurality of grooves spaced parallel to each other across the full length of the blade shown in the hidden lines of the  FIGS. 3 and 3   a . The placement of the grooves  45  and the guide bars  46  are more graphically shown in  FIG. 10  and as the oblique hidden lines in the embodiment of the forming board  30  in  FIG. 1 . In this way the blade is supported across the full width of the machine and will slide uniformly across the full width of the machine by pulling or pushing on one end of the blade. 
     This invention is an improvement in the angular slide arrangement as mentioned above in U.S. Pat. No. 4,280,869 in that cam followers in the slides of the blade that are not in this invention are additional complexity to the system and have much higher loads for moving the blade in the Machine direction  33  of  FIG. 1  which would be much more unreliable than the slide system of this invention. Additionally, the novel concepts of the roller assemblies in the slide base  38  as shown in  FIG. 7  and  FIG. 8  are to reduce the load of the jack screw actuator  36  and will be more fully realized and understood from the following detailed description when taken with the accompanying drawings. 
     This invention is also an improvement in Prior art because the forming board does not move with respect to the other drainage elements and foil blades on the Fourdrinier table thereby not impacting any changes to the harmonics of the papermaking process with changes in spacing between foil blades of the forming board and the foil blades of the next drainage box downstream. 
     SUMMARY 
     In accordance with the embodiment in  FIG. 3  and  FIG. 3 a    it is the object of this invention to move the leading edge of the Forming Board to the proper location as shown in  FIG. 2  such that the impingement of the jet from the slice opening of the headbox is split to provide for good formation, retention, and control of sheet properties resulting in improved sheet quality. 
     It is another objective of this invention as shown in the embodiment of  FIG. 4  that only the led blade of the forming board moves such that the spacing between foils downstream of the follower blade  43  is unchanged thereby not impacting any changes to the harmonics of the papermaking process with changes in spacing between foil blades of the Forming Board and the next foils of the Drainage box downstream. 
     Another objective of this invention as shown in the embodiment of  FIG. 7  and  FIG. 8  is to provide for rolling surfaces in the slide base  38  resulting in reduced loading on the jack screw actuator  36  for moving the lead blade back and forth along the plurality of guide bars  46 . 
     Another objective of this invention as shown in the embodiment of  FIG. 4  is to provide for moving the lead blade while the papermaking process is running. The jack screw actuator  36  can be connected to an electric motor in place of the hand wheel  39  to effect movement of the lead blade  29  remotely. Additionally, the lead blade can be moved remotely as shown in the embodiment of  FIGS. 10, 10   a , and  11 , by a plurality of servo gear-motor drives  68  that have brakes and load sharing capacity to position the lead blade  29  per the operator&#39;s discretion. A linear sensor can be attached to the lead blade  29  as feedback to any electric motor or servo motor system to limit the movement of the lead blade  29  from causing any damage to the equipment. 
     The novel concepts of the present invention will be more fully realized and understood from the following detailed description when taken with the accompanying drawings. In addition, other modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the disclosure. 
    
    
     
       DRAWINGS 
       Figures 
         FIG. 1  is a perspective view of the wet end of the Fourdrinier showing the headbox, forming board, and the next drainage element downstream of the forming board. 
         FIG. 2  is a fragmentary sectional view taken along the line  2 - 2  of  FIG. 1 . 
         FIG. 3  is fragmentary top view of the forming board  30  at the actuator end showing the lead blade  29  in the retracted position. 
         FIG. 3 a    is fragmentary top view of the forming board  30  at the actuator end showing the lead blade  29  in the extended position. 
         FIG. 4  is a perspective view of the forming board  30  at the actuator end showing the lead blade  29  in the retracted position. 
         FIG. 5  is an exploded view of the forming board at the actuator end. 
         FIG. 5 a    is a sectional view of the lead blade taken along the line  5   a - 5   a  of  FIG. 5 . 
         FIG. 6  is an exploded view of the forming board at the non-actuator end. 
         FIG. 6 a    is an exploded view of one end of the lead blade. 
         FIG. 7  is a fragmentary plan view of the slide base showing the addition of rollers mounted adjacent to the grooves of the slide base. 
         FIG. 7 a    is a sectional view of the slide base taken along the line  7   a - 7   a  of  FIG. 7 . 
         FIG. 8  is a sectional view taken along the line  8 - 8  of  FIG. 7 . 
         FIG. 9  is an exploded view of the roller assembly in the slide base. 
         FIG. 9 a    is an exploded view of a rack and pinion assembly in the slide base. 
         FIG. 9 b    is a perspective view of the pinion with roller bearing. 
         FIG. 9 c    is a partial view of the guide bar  46   a.    
         FIG. 10  is a partial view of an alternative embodiment of the invention for moving the lead blade  29  using a plurality of servo gear-motors  68 . 
         FIG. 10 a    is a sectional view taken along the line  10   a - 10   a  of  FIG. 10 . 
         FIG. 11  is an exploded view of a rack and pinion assembly in the slide base with one of the servo gear-motor drives  68  shown. 
         FIG. 11 a    is a perspective view of the pinion  65   c  with a keyway for fitting to the shaft of the servo gear-motor drive  68 . 
     
    
    
     DRAWINGS 
     References 
     
         
           21  is the head box. 
           22  is the paper slurry. 
           23  is the jet of slurry out of the slice opening. 
           24  is the top slice lip. 
           25  is the bottom slice lip. 
           26  is the wire. 
           27  is the breast roll. 
           27   a  is a wire return roll. 
           28  is the downward jet of slurry that splits ahead of the lead blade. 
           29  is the lead blade of the forming board. 
           29   a  is the gap between the lead blade and the follower blade. 
           29   b  is a ceramic cover. 
           29   c  is a groove in the lead blade on the downstream side. 
           30  is the forming board drainage box. 
           31  is the arrow indicating the downward direction of flow of the split jet of slurry. 
           32  is the arrow indicating the direction and point of impingement of the jet  23  to the lead blade. 
           33  is an arrow indicating the horizontal flow of the slurry on the wire. 
           33   a  is an arrow indicating the movement of the lead blade toward the headbox. 
           33   b  is an arrow indicating the movement of the Lead Blade away from the head box. 
           33   c  is an arrow indicating the movement of the lead blade along the grooves in the slide base toward the center of the Fourdrinier. 
           33   d  is an arrow indicating the movement of the lead blade along the grooves in the slide base away from the center of the Fourdrinier. 
           34  is an arrow indicating the direction of water flow draining through the wire. 
           35  is a gravity drainage box. 
           36  is a jack screw actuator. 
           36   a  is the jack screw of the actuator. 
           37  is the Fourdrinier Table. 
           38  is the slide base. 
           38   a  is the flushing hole drilled through the length of the slide base. 
           38   b  are a plurality of flushing holes in grooves of slide base. 
           39  is the jack screw hand wheel. 
           40  is the lead blade Scale. 
           41  is the lead blade Pointer. 
           42  is the lead blade connector block. 
           42   a  is the lead blade connector block pin. 
           43  is the follower blade. 
           44  is a forming board trail blade. 
           45  is a plurality of grooves in the slide base. 
           46  is a plurality of guide bars on the bottom of the lead blade. 
           46   a  is a plurality of guide bars with gear teeth for a rack and pinion. 
           46   b  are the guide bar fasteners. 
           46   c  are the holes for the guide bar fasteners. 
           46   d  are grooves cut in the bottom of the lead blade guide bars. 
           47  is a plurality of drain holes in the slide base. 
           48  is a jack screw stop collar. 
           49  is the jack screw support structure. 
           50  is the jack screw stop Disk. 
           50   a  is the stop disk T-handle pin. 
           51  is a tension rod. 
           51   a  are the tension rod holes in the lead blade. 
           52  are lead blade connector pin sleeves. 
           52   a  are lead blade connector pin fasteners. 
           52   b  are a plurality of holes in the end of the lead blade. 
           53  is the connector pin clamp plate. 
           54  is the follower blade T-bar. 
           55  is the jack screw rod end eye connector. 
           56  is the rod end eye ball bushing. 
           57  is the tension rod clamp plate. 
           58  is an arrow indicating the cross machine direction. 
           59  is a dovetail clamp plate. 
           59   a  is the slide base Dovetail. 
           60  is the roller shaft. 
           61  is roller block assembly. 
           62  is a plurality of threaded holes in Slide Base to attach follower Blade T-bar. 
           62   a  are the plurality of fasteners that hold the T-bar  54  on the slide base  38 . 
           63  is the threaded hole in the roller shaft. 
           64  is the roller retaining bolt. 
           64   a  are the roller block retaining bolts. 
           65  is the roller with bearing. 
           65   a  is the roller bearing. 
           65   b  is the gear tooth pinion with a bearing. 
           65   c  is the gear tooth pinion keyed for a shaft. 
           65   d  is the keyway in the gear tooth pinion. 
           66  is the top clamp plate. 
           66   a  is a slotted hole. 
           67  is the bottom clamp plate. 
           67   a  is a slotted hole. 
           68  is a servo gear-motor drive with keyed shaft. 
           68   a  are the servo gear-motor covers. 
       
    
     DETAILED DESCRIPTION 
     First Embodiment—FIGS.  1 ,  2 ,  3 ,  3   a ,  4 ,  5 ,  5   a ,  6 , &amp;  6   a    
       FIG. 1  illustrates a typical Fourdrinier at the wet end including the headbox  21  and the first two drainage boxes, the forming board  30  and the next gravity drainage box  35 . Just below the Headbox  21  is the breast roll  27  and a wire return roll  27   a  for which the wire  26  extends over and around the breast roll  27  and continues down the Fourdrinier  37  in the direction  33 . The wire  26  is supported by drainage elements, two of which are shown in  FIG. 1 , the forming board  30  and the first gravity box  35 . Under ideal conditions the slurry  22  inside the headbox  21  forms a jet  23  which emerges out of the slice opening of the headbox  21  and impinges directly on the wire  26  and in the proper position for which the leading edge of the lead blade  29  of the forming board  30  will split the flow of the slurry  22  into two flows. The majority of this flow of slurry  22  will stay in a horizontal direction  33  to be drained of water down the length of the Fourdrinier  37  and a minor flow of slurry  22  will be directed downward at the leading edge of the lead blade  29 . Also illustrated in  FIG. 1  is the jack screw actuator  36  that moves the lead blade  29  at the discretion of the operator to position the leading edge of the lead blade  29  in the proper position for the jet  23  impingement on the wire  26 . The lead blade  29  moves in a plurality of groove in the slide base  38  which is fixed to the forming board  30 . The headbox  30  is the embodiment of the top slice lip  24  and the bottom slice lip  25 . In typical headbox configurations the top slice lip  24  can move vertically or horizontally to create a slice opening out of the headbox  21  across the width (direction  58 ) of the Fourdrinier  37  for which the jet  23  emerges. Direction  58  is known as the cross machine direction and which is right angle to the direction the wire  36  is moving. 
       FIG. 2  illustrates important machine and jet parameters associated with the jet  23  trajectory. This is in the area just downstream of the headbox  21  and the breast roll  27  and for which the wire  26  is supported by the forming board  30 . The parameters are defined as follows:
         a. b=slice opening   b. t=jet thickness at the vena contracta   c. t 2 =thickness of the slurry  2  above the wire  6  moving horizontally in direction  13     d. t 3 =the thickness of the slurry  2  that is directed down in the direction  11  and is split at the leading edge of the lead blade  9     e. d=the distance from the leading edge of the lead blade  9  to the edge of the bottom slice lip  5     f. h=the height of the top surface of the bottom slice lip  5  to the top surface of the wire  6     g. I=the bottom slice lip  5  extension beyond the top slice lip  4  edge       

     An explanation of the physics used to analyze the jet  23  trajectory is given in various textbooks. One such reference is The Institute of Paper Chemistry (IPC) technical paper series number 206 “Fourdrinier Jet Geometry” by Douglas Wahren, November 1986. This paper is specific to the paper industry while keeping with the physics principles of science. 
     The jet  23  emerges from the slice opening of the headbox  21  at a velocity which is a function of the opening “b” and the total pressure head inside the headbox  21 . This total pressure head is the sum of the static and velocity head of the flow of the slurry  22 . This opening is set with the movement of the top slice lip  24  with respect to the bottom slice lip  25 . The bottom slice lip  25  is permanently fixed to the headbox  21  at the elevation “h” above the wire  26 .  FIG. 2  shows the bottom slice lip  25  in a horizontal position however it can be tilted at a different angle with the tilting of the headbox  21 . 
     The jet  23  contracts to a minimum thickness “t” at the vena contracta approximately a distance “b” downstream of the edge of the top slice lip  24 . The amount of this contraction is a function of the headbox  21  bottom slice lip  25  tilt angle (shown horizontal in  FIG. 2 ) stock properties of the slurry  22 , and I/b ratio. Under ideal conditions as shown in  FIG. 2 , the jet  23  is split into two components, one, a downward slurry, jet  28 , in the direction of  11  ahead of the lead blade  29  and the remaining slurry  22  following the horizontal direction  33  along the wire  26  at approximately the same velocity of the wire  26 . This split should be in the range of 5% to 10%. The velocity of the jet  23  points in a downward direction  32  and is the point at which the jet  23  impinges at the leading edge of lead blade  29 . The velocity of the jet  23  at the point of impingement in the direction of  32 , at a distance “d” from the end of the bottom slice lip  25 , has a horizontal component in the direction of  33  and a vertical component due to the effect of gravity, the tilt angle of the headbox  21  (horizontal as shown in  FIG. 2 ) velocity of the jet  23  emerging from the headbox  21 , and the height “h” of the bottom slice lip  25  above the wire  26 . The thickness of the Jet  28  “t 3 ” plus the thickness of the horizontal flow of the slurry  22  above the wire  26  “t 2 ” is equal to the thickness of the jet  23  at the vena contracta “t”. 
       FIG. 2  shows the lead blade  29  in the farthest position downstream such that there is no gap between follower blade  43  and the trailing edge of the lead blade  29 . If the wire speed or the stock consistency of slurry  22  is to change the position of impingement of the jet  23  will also change. The movement of the lead blade  29  is designed to slide over the slide base  18  to accommodate changes in the impingement point of jet  23  such that the jet  23  will split in the percent required for the best sheet quality of the slurry  22 . The slide base  38  is secured in a dovetail structure of the forming board  30  and held in place with a dovetail clamp plate  59  thereby facilitating the movement of the lead blade  29  sliding over the slide base  38 . This movement will be more fully realized in the following detailed description when taken with the accompanying drawings. 
     Additionally as part of the forming board  30 , there are trailing blades  44  which doctor off the water that drains through the wire  26  in the direction  34  and which results in increased consistency of the slurry  22  as it moves down the wire  26 . 
       FIG. 3  is fragmentary top view of the forming board  30  at the actuator end. The actuator is usually on the back side of the Fourdrinier however can be mounted on the front side as well.  FIG. 3  shows the lead blade  29  in the retracted position such that there is no gap between the lead blade  29  and the follower blade  43 . The jack screw actuator  36  is a worm gear driven jacking screw with anti-backlash characteristics. Typically this actuator assembly would be mounted on the back side of the machine as the wire  26  is replaced from the tending side of the machine. The jack screw actuator  36  is connected to the lead blade  29  through the lead blade connector block  42 . When the jack screw actuator  36  is rotated by the jack screw hand wheel  39  in the proper rotation it moves the jack screw  36   a  along the direction  33   c  or at angle “x” from the cross machine direction  58  in  FIG. 1  and which is parallel to the slide bars  46  attached to the bottom of the lead blade  29 . This action forces movement of the lead blade  29  away from the headbox  21  in the direction of  33   b . This is because the guide bars  46  are mated with the grooves  45  in the slide base  38  which is fixed to the forming board  30 . The movement of the lead blade  29  in the direction of  33   c  is a trigonometric function of the angle “x” to accomplish the desired movement in the direction  33   b  and is the reason the lead blade  29  and the slide base  38  must be wider than the Fourdrinier Table  37 . The guide bars  46  and grooves  45  are spaced across the full length of the machine as shown in  FIGS. 3 and 3   a  by the hidden lines of the lead blade  29 . In this way the lead blade  29  is supported across the full width of the machine and will slide uniformly across the full width of the machine by pulling or pushing on one end of the lead blade  29  with the jack screw actuator  36 . 
     It follows that the smaller angle “x” in  FIG. 3 , the farther the lead blade  29  has to move in the direction of  33   c  for a given distance in the  33   a  direction resulting in a longer lead blade  29 . It also follows that the smaller angle “x” in  FIG. 3  the lower the force is at the jack screw actuator  36 . There are always practical limits to the length of the lead blade  29  and the angle “x” in  FIG. 3  can be optimized for the loading verses the movement providing for optimal length of the lead blade  29 . 
     The lead blade pointer  41  is fixed to the lead blade connector block  42  and moves over the lead blade scale  40  which is fixed on the jack screw support structure  49  and indicates the position of the lead blade  29  with respect to the distance from the bottom slice lip  25  or the distance “d” in  FIG. 2 . 
     The jack screw stop collar  40  is fixed to the jack screw  36   a  and prevents the jack screw actuator  36  from damaging the follower blade  43 . The jack screw hand wheel  39  can be replaced with a remotely controlled electric motor. Once the lead blade  29  has been set in position the jack screw stop disk  50  can be pinned in place with the stop disk T-handle pin  50   a  to hold the position of the lead blade  29 . 
       FIG. 3 a    is fragmentary top view of the forming board  30  at the actuator end showing the lead blade  29  in the extended position such that there is a gap  29   a  between the lead blade  29  and the follower blade  43 . The jack screw actuator  36  which is connected to the lead blade  29  through the lead blade connector block  42  moves the lead blade  29  in the same way as described in  FIG. 3  only in the opposite direction along the direction  33   d  or at angle “x” from the cross machine direction  58  in  FIG. 1  and which is parallel to the slide bars  46  attached to the bottom of the lead blade  29 . The action of the jack screw actuator  36  subsequently forces movement of the lead blade  29  toward the headbox  21  in the direction of  33   a . The movement of the lead blade  29  is forced to slide along the grooves  45  in the slide base  38  because the guide bars  46 , being attached to or a part of the bottom of the lead blade  29 , mate to the grooves  45  and are at the same angle “x” to the guide bars  46 . 
       FIG. 4  is a perspective view of the forming board  30  at the actuator end showing the lead blade  29  in the retracted position of  FIG. 3 . 
       FIG. 5  is an exploded view of the forming board assembly as shown in  FIG. 4 . This view more clearly shows the mechanical linkage between the jack screw actuator  36  and the lead blade  29 . It may for example consist of a threaded connection between the jack actuator screw  36   a  and the jack screw rod end eye connector  55  that houses a rod end ball bushing  56  and pinned with a lead blade connector block pin  42   a  to the lead blade connector block  42 . The installation of the ball bushing  56  provides for a universal joint to eliminate the binding forces for misalignment of the jack screw assembly. This assembly is apparent to those skilled in the art. 
       FIG. 5  also shows a means by which the lead blade  29  is secured to the lead blade connector block  42  by a plurality of lead blade connector sleeves  52  that fit in the mating holes  52   b  in the end of the lead blade  29 . The connector sleeves  52  are held in place with the lead blade connector pin fasteners  52   a  in conjunction with the lead blade connector pin clamp plate  53 . The lead blade connector pin clamp plate  53  allows for the heads of the lead blade connector pin fasteners  52   a  to be tack welded in place to prevent the fasteners from coming lose during operation of the papermaking process. Another means of fastening the lead blade connector block  42  to the lead blade  29  is through the use of a plurality of tension rods  51  that are installed through channels in the lead blade  9  and connected with a threaded journal to the lead blade connector block  42 . The tension rods  51  serve to help transfer the end load from the jack screw actuator  36  to the total length of the lead blade  29  such that stress is reduced to the ceramic material that is a part of the materials of construction of the lead blade  29 . 
     Another illustration in  FIG. 5  is the assembly of the jack screw stop disk  50  that is keyed to the shaft of the jack screw actuator  36  and provides for a means by which the jack screw actuator  36  can be locked in place after final positioning. This is done by installing the stop disk T-handle pin  50   a  in a hole of the jack screw stop disk  50  and aligned most closely with a fix hole in the jack screw support structure  49 . Upon removal of the stop disk T-handle pin  50   a  the jack screw actuator  36  can be free for rotation with the jack screw hand wheel  39 . 
       FIG. 5 a    is a sectional view of the lead blade taken along the line  5   a - 5   a  of  FIG. 5 . This view shows the channels or tension rod holes  51   a  that the tension rods  51  are installed through for the full length of the lead blade  29 . Also illustrated is the ceramic cover  29   b  that the lead blade  29  is a composite of. The shape of the lead blade  29  including the angle “Y”, shown in  FIG. 5 a   , is an important parameter for determining what the split of the jet  23  ratio “t 3 /t 2 ” should be. 
     The bottom of the guide bars  46  have a small groove  46   d  cut to allow for flushing water to keep the grooves  45  in the slide base  38  clean and lubricated for reduced friction with the guide bars  46 . 
     The downstream edge of the lead blade  9  has a groove  29   c  the full length of lead blade  29 . This groove serves to provide a relief for stock build-up between the lead blade  29  and the follower blade  43  when the lead blade  29  is in the retracted position such that the gap  29   a  in  FIG. 3 a    is zero distance. 
       FIG. 6  is an exploded view of the forming board at the non-actuator end or on the tending side of the Fourdrinier and illustrates more fully how the tension rods  51  are clamped on the end of the lead blade  29  with the tension rod clamp plate  57 . The tension of the tension rods  51  can be adjusted with a threaded nut on the end of the tension rod  51  against the clamp plate  57 . 
     Also shown is the follower blade  43  that slides on the follower blade T-bar  54 . The T-bar  54  is fixed to the slide base  38  with a plurality of threaded fasteners  62   a  that match the threaded holes  62  in the slide base  38  shown in  FIG. 7 . 
       FIG. 6 a    illustrates an alternative detachment of the guide bars  46  that are attached to the bottom of the lead blade  29  at angle “x” shown in  FIG. 3  such that the guide bars can be made of a metal or dissimilar material from the composite material of the lead blade  29  and can be assembled on the bottom of the lead blade  29  with guide bar fasteners  46   b  through holes  46   c . This will provide for reduced coefficient of friction between the sliding parts of the guide bars  46  attached to the lead blade  29  and the grooves  45  in the slide base  38  with the resultant reduction in load on the jack screw actuator  36 . 
     Operation 
     First Embodiment—FIGS.  1 ,  2 ,  3 ,  3   a ,  4 ,  5 ,  5   a ,  6 , &amp;  6   a    
     The operation of positioning the lead blade  29  of the forming board  30  to the headbox  21  a distance “d” from the bottom slice  25  to the lead blade  29  shown in  FIG. 2  is done without having to move the whole embodiment of the forming board  30 . Only the lead blade  29  is moved. This is simply done by the jack screw actuator  36  from one end (usually the back side). The jack screw actuator  36  moves the lead blade  29  along the direction of  33   c , which is at angle “x” shown in  FIG. 3  or the opposite direction of  33   d  shown in  FIG. 3 a   , depending on the direction of rotation of the hand wheel  39 . The guide bars  46  attached to the bottom of the lead blade  29  are embedded in the grooves  45  of the slide base  38  which is fixed to the forming board  30 . The movement of the lead blade  29  along the grooves  45  in the slide base  38  results in the movement of the lead blade  29  toward the headbox  21  to attain the distance “d” and is indicated with the pointer  41  on the scale  40  shown in  FIG. 3 a   . As the distance “d” in  FIG. 2  decreases the gap  29   a  in  FIG. 3 a    increases which provide for an opening between the lead blade  29  and the follower blade  43 . The gap  29   a  will allow water to drain through the holes  47  in the slide base  38 . The size and shape of these holes are significant for controlling the amount of water that drains through the wire  26 . Additionally the shape of the follower blade  43  can have ramifications on how much water is drained and how much activity the blade may impart into the slurry  22 . The follower blade  43  is stationary and will maintain the blade spacing from that point downstream such that the harmonics of the system is not affected. 
     After the lead blade  29  is set in position it can be locked in place with the stop disk  50  and pinned in place with the stop disk pin  50   a  shown in  FIG. 3 a   . This will lock the jack screw  36  in place which will hold the lead blade  29  in the set position. 
     DETAILED DESCRIPTION 
     Second Embodiment—FIGS.  7 ,  7   a ,  8 ,  9 ,  9   a , &amp;  9   b    
       FIG. 7  is a fragmentary plan view of the slide base  38  showing the addition of roller block assemblies  61  mounted in pairs, adjacent to and on each side of selected grooves of the slide base  38 . There may be two or more pairs of roller block assemblies  61  equally spaced along the full length of the slide base  38 . This is an improvement over the first embodiment in that the rollers assemblies  61  will reduce the frictional forces between the guide bars  46  and the grooves  45 . 
     Also shown in  FIG. 7  are flushing holes  38   a  and  38   b  which provide a channel in the slide base  38  for the addition of flushing water to clean the grooves  45  of any stock build-up from the drainage of the slurry  22 . This flushing water can be connected to the flushing hole  38   a  at the end side of the slide base  38  on the tending side. Additionally the flushing water will provide some lubrication of the sliding surfaces between the grooves  45  and the guide bars  46 . 
     Another feature shown in  FIG. 7  are the plurality of drain holes  47  that are cut out of the downstream side of the slide base  38  to allow for water drainage between the downstream edge of the lead blade  29  and the follower blade  43 . This area is shown as gap  29   a  on  FIG. 3 a   . The shape of these cut-outs in the edge of the slide base  38  can be made any size or shape to restrict the drainage of the slurry  22  in this area of the forming board  30 . 
       FIG. 7 a    is an end view of the slide base  38  and most notably shows the shape of the slide base dovetail  59   a  that matches the dovetail shape in the structure of the forming board  30 . The dovetail clamp plate  59  shown in  FIG. 2  secures the slide base  38  to the forming board  30 . The dovetail clamp plate  59  is a long narrow strip of metal that crosses the width of the Fourdrinier and is held in place with a plurality of threaded fasteners clamping the slide base  38  to the structure of the forming board  30 . 
     The flushing hole  38   a  is blind drilled in the end of the slide base  38  from the tending side to a point at the actuator end of the slide base  38  such that flushing water can enter the last of the grooves  45  through one of the flushing holes  38   b . The flushing water subsequently can enter the groove  46   d  in the guide bars  46  as shown in  FIGS. 5 a    and  8 . The flushing holes and channels provide flushing water to all parts of the system when required. 
       FIG. 8  is a sectional view that illustrates the details of the roller block assembly  61 . The roller  65  is fitted with a plain bearing to allow rotation on the roller shaft  60  and positioned to contact the edge of the guide bar  46  providing a rolling surface for the guide bar  46  to move on. The roller block assembly  61  is installed in pairs on each side of the grooves  46  to provide a rolling surface for movement of the guide bars  46  in either direction  33   c  in  FIG. 3 or 33   d  in  FIG. 3 a   . The roller shaft  60  has a threaded hole  63  to provide for the roller retaining bolt  64  which holds the roller  65  in place. The top clamp late  66  and the bottom clamp plate  67  are secured to the slide base  38  in recessed holes adjacent to a groove  45 . The assembly of the parts is more fully realized in the following detailed description when taken with the accompanying drawings. 
     The fit between the guide bars  46  and the grooves  45  is best illustrated in  FIG. 8 . This fit can have the shape of a T-bar as shown in the figures of these embodiments or it can have other shapes such as a dovetail  59   a  as shown for the fit between the slide base  38  and the forming board  30  structure in  FIG. 2 . The fit between the guide bars  46  and the grooves  45  in the slide base  38  must provide the proper clearance to allow thermal expansion such that the sliding action of the guide bars in the grooves is not impeded for the temperatures of operation of the papermaking process. 
       FIG. 9  is an exploded view of the roller block assembly  61  as shown in  FIG. 8 . Illustrated is how the roller block assembly  61  is fastened to the slide base  38  with the roller block retaining bolts  44   a . Also shown more explicitly is the slotted hole  66   a  in the top clamp plate  66  and the slotted hole  67   a  in the bottom clamp plate  67  and which allow for adjustment of the position of the roller  65  for contact against the edge of guide bar  46 . An alternative method of adjustment for the roller  65  is to have the roller mounted on an eccentric sleeve much as done in the industry for cam followers and is apparent to an expert in the field. 
       FIGS. 9 a , 9 b  and 9 c    illustrate another embodiment of the roller block assembly  61  such that the roller  65  is replaced with a gear  65   b  and which has a plain bearing  65   a . Additionally, the guide bars  46  is replaced with a guide bars  46   a  that have mating gear teeth to gear  65   b  and provide for a rack and pinion assembly that keeps the gear rotating with movement of the lead blade  29 . The improvement of this assembly over the assembly described in  FIG. 8  is that the bearings will always rotate and never seize up. Also the rack and pinion design sets the stage for moving the lead in an alternative way which will become more fully realized in the following detailed description when taken with the accompanying drawings. 
     DETAILED DESCRIPTION 
     Third Embodiment—FIGS.  10 ,  10   a ,  11 , &amp;  11   a    
       FIGS. 10, 10   a ,  11 , &amp;  11   a  is an alternative embodiment for moving the lead blade  29  such that the jack screw actuator  36  is no longer needed on the back side of the Fourdrinier to move the lead blade  29 . This is illustrated in  FIG. 10 . The jack screw actuator  36  is replaced with a plurality of servo gear-motor drives  68  shown in the hidden lines in  FIG. 10 . 
       FIG. 10 a    is a sectional view that shows one of the servo gear-motor drives  68  that is keyed to the gear tooth pinion  65   c  and can rotate pinion gear  65   c  such that the guide bar  46   a  with matching gear teeth will move the lead blade  29  in unison with the other servo gear-motor drives  68  to the desired position as shown in  FIG. 2 . These servo gear-motor drives  68  can be a right angle gearbox arrangement to keep the profile of the gear-motor as small as possible and to allow for a cover  68   a  to protect the servo gear-motor  68  from fluid flow of the slurry  22  drainage through the wire  26 . Alternatively the cover can be made to hermetically seal the servo gear-motor off from the fluid flow of the drainage from the slurry  22 . The control of these servo gear-motor drives  68  can be a simple load sharing drive that will work in unison to move the lead blade  29 . The torque loading requirement of these servo gear-motor drives  68  is dependent on the angle “x” in  FIG. 10  and the number of drives installed. 
       FIGS. 11 and 11   a  shows more clearly how the servo gear-motor drive  68  is keyed to the gear tooth pinion  65   c  with the slot  65   d . The pinion  65   c  meshes with the gear teeth of  46   a  which are connected to the bottom of the lead blade  29  similar to the guide bars  46  shown in  FIG. 6   a.    
     One of the major advantages to the third embodiment with the servo gear-motor drives is that if properly sized the angle “x” can be greater than 45 degrees to as high as 90 degrees eliminating the need for a lead blade  29  that is wider than the forming board  30 . 
     Operation 
     Third Embodiment—FIGS.  10 ,  10   a ,  11 , &amp;  11   a    
     The operation of positioning the lead blade  29  of the forming board  30  to the headbox  21   a  distance “d” from the bottom slice  25  to the lead blade  29  shown in  FIG. 2  is done remotely with the use of the servo gear-motors  68  in the third embodiment of the invention.  FIG. 11  shows the connection to the lead blade  29  such that when the servo gear-motor  68  provides torque to rotate the pinion gear  65   c  that force is transmitted to the gear teeth of the guide bars  46   a  which in turn moves the lead blade  29  linearly in the slide base  38 . 
     CONCLUSIONS, RAMIFICATIONS, AND SCOPE 
     Accordingly the reader will see that, the embodiments of the invention, has provided a means to position the lead blade  29  of the forming board  30  such that the emerging jet from the headbox  21  impinges at the proper position on the lead blade  29  to provide for improved sheet quality and limit air entrapment in the slurry  22  as the slurry  22  continues to drain along the length of the Fourdrinier. This invention focuses on moving the lead blade  29  only and not moving the forming board  30  with to all of the trailing blades  44  which will require more expensive hardware such as cross shafts with large gearboxes. Additionally, by not moving the whole forming board  30  the risk of upsetting the harmonics of the sheet formation on the Fourdrinier is reduced. This is because the distance between the forming board trailing blades  29  to the other drainage elements downstream does not change. 
     The first embodiment of this invention as shown in  FIGS. 1, 2, 3, 3   a ,  4 ,  5 ,  5   a ,  6 , &amp;  6   a  has a unique feature in that it is easily retro-fit able to most forming boards because of the dovetail  59  design as shown in  FIG. 7 a   . All that is required is to build a slide base  38  that matches the fit to the dovetail of a standard lead blade of most forming boards. Additionally the slide base  38  can be fixed to the forming board  30  by any type of fastening system that is different than the standard dovetail system commonly used in the art. 
     The second embodiment of this invention as shown in  FIGS. 7, 7   a ,  8 ,  9 ,  9   a ,  9   b , &amp;  9   a  is an improvement of the first embodiment by reducing the forces of the jack screw actuator  36  for moving the lead blade  29  back and forth in the plurality of grooves  45  of the slide base  38 . This is done with roller bearings to reduce the friction load from the sliding action of the guide bars  46  and the grooves  45  and flushing holes which help keep the grooves  45  clean. 
     The third embodiment of this invention as shown in  FIGS. 10, 10   a ,  11 , &amp;  11   a  requires the re-work of an existing forming board or the manufacture of a new forming board to allow the installation of the plurality of servo gear motor drives  68  to move the lead blade  29  in the same way as the first embodiment. While the third embodiment is more expensive than the first embodiment the third embodiment has the advantage of distributing the forces of movement of the lead blade  29  along the full length of the blade eliminating the need for the tension rod  51 . This is because when the force of movement is applied at one end as shown in the first embodiment the tension rods  51  transfer the load to the end of the lead blade  29  when actuated by the jack screw actuator  36  from one end. Another advantage of the third embodiment is that the angle “x” shown in  FIG. 10  can be greater than 45 degrees and as high as 90 degrees eliminating the need for a longer lead blade  29  that is wider than the forming board  30 . The first embodiment is limited to an angle “x” to less than 45 degrees because the forces required for moving the lead blade  29  would be too great at the jack screw actuator  36 . 
     While the above description contains many specifics, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of various embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. For example, the shape of the drainage holes  47  shown in  FIG. 7  can be made circular or triangular to regulate the rate of flow of water through this area as the gap  29   a  shown in  FIG. 3 a    increases with the movement of the lead blade  29  toward the headbox  21 . Another ramification is that the jack screw  36  can be driven by an electric motor and the scale  40  and pointer  41  can be replaced by a linear indicator to provide feedback to the electric motor to allow for remote control of the position of the lead blade  29 . Additionally the electric motor can be fit with an integral brake to maintain the position of the lead blade  29 . Thus the scope should be determined by the appended claims and their legal equivalents, and not by the examples given.

Technology Classification (CPC): 3