US3027941A - Fourdrinier white water doctor box - Google Patents

Description

April 3, 1962 H. E. DUNLAP FOURDRINIER WHITE WATER DOCTOR BOX 2 Sheets-Sheet 1 Filed Nov. 24, 1959 INVENTOR HAROLD E. DUNLAP ATTORNEY April 3, 1962 H. E. DUNLAP 3,027,941

FOURDRINIER WHITE WATER DOCTOR BOX Filed Nov. 24, 1959 2 Sheets-Sheet 2 INVENTOR HAROLD E. DUNLAP ATTORNEY 3,027,941 FOURDRINIER WHHTE WATER DGfiITQR BOX Harold E. Dunlap, Dudley, Mass, assignor to Lodtiing Engineering Corporation, Auburn, Mass, a corporation of Massachusetts Filed Nov. 24-, 1959, Ser. No. 855,119 7 Claims. (Cl. 162-452) This invention relates to a new and improved supporting apparatus for the Fourdrinier wire or screen in the paper making industry, and the principal object of the invention resides in the provision of a novel grid-like doctor box to induce drainage of white water through the Fourdrinier wire to a greater extent than table rolls, deflectors, or low vacuum suction box covers of the prior art; to provide a doctor box of the class described of high drainage efiiciency and which occupies a relatively small area in the length of the Fourdrinier wire; and in general to improve the drainage of the white water by an improved mechanism embodying the principal advantages of rolls, deflectors and suction boxes while providing for improved paper manufacture over the devices used in the prior art for the induction of drainage of the water through the Fourdrinier wire.

Normally in the prior art Fourdrinier wires are supported by table rolls, deflectors or suction boxes or combinations of the same, and while deflectors do not usually induce drainage of water through the wire, they skive away water which is suspended from the under side of the wire and in this way aid in the gradual drying of the pulp. Table rolls generate a short length vacuum directly past the roll center line in the area where the wire is leaving contact with the roll, and this helps to induce drainage through the wire, but water passing through the Fourdrinier wire by gravity between supporting table rolls is generally believed to be relatively small factors in the over-all drainage phenomena; therefore it is clear that the percentage of wire exposed to various suction areas is directly related to the rate of water drainage through any particular unit length of Fourdrinier wire. The present invention takes the place of deflectors, table rolls, and certain low vacuum suction boxes and does away with the need for this type of apparatus.

Further objects of the present invention reside in the provision of a plurality of Fourdrinier wire contacting doctor surfaces within a short unit length of wire, each surface being shaped to first skive the depending water at the under side of the Wire, and secondly to generate a break-away vacuum as the Fourdrinier wire travels past a curved top surface which is applied to each such contacting surface; and the provision of a new and improved supporting construction for the plurality of the individual doctors or the like.

The invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly set forth in the appended claims.

Reference is to be had to the accompanying drawings, in which:

FIG. 1 is a top plan view illustrating the invention applied to a part of a paper-making machine, the Fourdrinier wire being omitted;

FIG. 2 is a longitudinal section through the same showing the position of the breast or table roll;

FIG. 3 is a section on a slightly enlarged scale taken on line 33 of FIG. 1;

FIG. 4 is a view in side elevation on a slightly enlarged scale, looking in the direction of arrow 4 in FIG. 1;

FIG. 5 is a perspective detail view showing the construction of an auxiliary supporting means;

FIG. 6 is an enlarged sectional view on line -d of FIG. 2, certain parts being omitted; and

bttes i atent i 3,5521%]. Patented Apr. 3, 1962 FIG. 7 is an enlarged sectional view on line 7-7 of FIG. 2, certain of the parts being omitted.

As shown in the drawings, the device of the present invention is adapted to be supported between the shake rolls ordinarily found in a Fourdrinier machine, but it is to be emphasized that the apparatus can be mounted in any other way and on any other machine supports if desired. FIG. 1 shows only a portion of the device which may extend across the entire Fourdrinier wire from one shake rail to the other, but it is emphasized also that this is merely illustrative and that a series of apparatuses to be described may be used to extend across a Fourdrinier wire and that other and supplemental supports may be utilized if it should become desirable or necessary for this purpose.

In FIGS. 1, 3 and 4, one of the shake rails at one side of the Fourdrinier wire is indicated by the numeral 10. As illustrated herein, a plate 12 may be secured to the shake rail, it being understood that the construction at the opposite side of the machine is generally the same but reversed. Plate 12 may be secured in position by bolts 14 which if desired may adjustably position plate 12 longitudinally of the shake rail and of the machine by extending through slots 16 in plate 12, see FIG. 1. Plate 12 may be provided with a side flange or the like 1-8 to aid in positioning the same, and it may also be provided with any kind of supports, washers, or the like 24 20.

The plate 12 has mounted in fixed position thereon an upright boss or the like 22 and this may conveniently support a threaded shaft 24 having a head 26 by which it may be rotated, a lock nut 28, and an operative forward end at 3%.

The shaft 24 at its forward end 30 is engaged with an abutment 32 which is mounted on a plate 3 3 fixedly secured to a top plate 36 clamping with a bottom plate 31% the ends of a series of spaced elongated upright thin metal strips or plates 45 This clamping action is achieved by means of screw-threaded members 42, see particularly FIG. 3. Plates 36 and 38 are ground for accurately holding the strips 4%} which extend in upright condition transversely across the machine just under the Fourdrinier wire as perhaps best illustrated in FIG. 2 where the Fourdrinier wire is indicated by the letter F. As stated above, the elongated plates 4% may extend across the machine completely or in a series of overlapping members which are secured together in any manner or to a common base.

Top plate 36 may be supported adjustably upon plate 12 by any desired means such as the adjustable bolts 46 and it will be apparent that when shaft 24 is turned in the appropriate direction, this wiil tend to move member 32, plate 34- and plates 36 and 38 in one direction or the other crosswise of the machine. In this way, with similar but reversed mechanism at the opposite side of the machine or at the other ends of strips 40, endwise pressure is applied to said strips to bow them in parallel formation as shown in FIG. 1 and the degree of flexure of strips 40 and therefore the degree of curvature involved is dependent upon adjustment of shaft 24.

Each transverse strip 4t) has an upper free edge, see FIGS. 2 and 3, this having been indicated by the reference numeral 46. The strips 40 are rectangular and the upper edges thereof extend across the apparatus horizontally and form a support for the individual doctor blades generally indicated by reference numerals 48. These blades may conveniently be extruded and it has been found that if they are made of a conventional thermoplastic such as vinyl, they are very efficient and longlasting and are not unduly worn by the action of the Fourdrinier wire, as may have been expected from the use of such a plastic material.

sea/3941 In any event, each doctor blade 48 is provided with a curved top surface 50 which is related to a longitudinal generally central slot 52., see FIGS. 2 and 3, in such a way that when the blades 48 are mounted at the top edges 46 of strips 40 they are held in a position which provides a retreat on a curve from the lower surface of the Fourdrinier wire F. This curvature forms a vacuum as the Fourdrinier wire passes thereover in the direction of the arrow in FIG. 2 so as to induce drainage of water from the pump on the wire, this water then being doctored or skived from the under side of the wire by the leading edge of the following doctor blade 5t? falling between respective strips 40 to a drainage surface such as for instance 54, see FIG. 2.

The forward or leading edge 56 of each blade 48 is relatively sharp and this is arranged in such a way as to contact the under side of the Fourdrinier wire and skive any depending water therefrom, and this water will also fall by gravity between the thin gauge metal strips 40. This of course eliminates the pressure area built up on the front side of the usual rotating table roll as is well known in the art, and thus this invention provides a combined drainage both as to the skiving action of the forward portion of the blade 48, and the suction or vacuum action along the top surface toward the rear thereof as explained, so that an extremely eflicient water drainage device is provided. This is particularly true in view of the fact that the blades 48 are comparatively narrow and a plurality of the same may be applied where desired while still leaving a very great deal of opening for the water to descend through, as opposed to providing surfaces which may tend to defeat the purpose of the drainage such as in the usual suction box cover.

The thin gauge metal strips 40 are formed into a grid by a novel construction which includes a series of pairs of elongated bolts 58, these bolts being longitudinally slotted as at 60 for the reception diametrically therethrough of a series of new and improved spacer plates generally indicated at 62 and 64. It will be noted that the bolts 58 are solid at their end portions 66 but are slotted for the remainder of their lengths.

The spacers 64 are provided with a rounded ground-off edge 68, see FIG. 7, and by extending through the terminal portions of the slots of bolts 58, form end stops with the rounded edges 68 contacting the leading metal strips 40. The spacers 62 are somewhat similar but may be rectangular in shape and they are provided with rounded edges 70 and 72 fore and aft, see FIG. 6, so that extending as they do between each next adjacent pair of metal strips 40, the rounded edges thereof at 70 and 72 contact the metal strips, and in this way the entire construction is made in a grid form of relatively small area.

The opposite ends of the bolts 58 are threaded as at 74 for the reception of nuts 76 which bear on the elongated beveled surfaced washers 78, the bevel being shown at 80 and contacting the rear surface of the rearwardmost metal strip 40 along a more or less rounded nose contact or line contact as shown in FIG. 1. The spacers may be staked to the bolts if desired as indicated in FIG. 2.

The blades 48 may be replaced when worn and in any event they are very inexpensive to manufacture and are easily applied to and removed from the top edges at 46 of the metal strips 40. The grid construction provides plenty of room for the water to be discharged and the depth of the grid members may vary as needed with machine width, stock, weight, or other machine variables also. If an extremely long device is to be made, it may be supported by means of any kind of central support as for instance as shown in FIG. 5 wherein an inverted angle-iron indicated at 82 is provided at the top surface thereof with cross-bars 84 upon which the grid may rest at the bottom edge thereof. Additional supports may be used if necessary with backing up members for the strips, etc. if this should become desirable, see dot-and-dash lines of FIG. 5.

The new white water doctor box presents a plurality of Fourdrinier wire-contacting doctor surfaces within a very short length of the Fourdrinier wire. Each doctor first skives water hanging from the under side of the wire and then generates a break-away vacuum as the Fourdrinier wire travels past and off the curved top surfaces of the individual doctors 43. Although the unit shown has six wire contacting surfaces or blades 48, the actual number of such blades may be varied as required to suit individual conditions.

The devices of the class described may be substituted for the usual rollers or deflectors and provide support for the wire while increasing the water drainage therefrom over the rolls, suction boxes and deflectors of the prior art. By the use of the present invention, the pump may have a great deal more water extracted therefrom per unit length of Fourdrinier wire than devices of the prior art so that the wire may he traveled faster or the time of process thereof may be cut down considerably.

The combined features of a deflector and rotating roll i.e., skiving edge and vacuum generation with the elimination of the pressure area built up on the front side of rotating rolls, improves formation of the paper being made. Formation refers to matting or interlocking of individual pulp fibers and the retention of fines and fillers. The elimination of the roll pressure nip reduces the tendency for matted fibers to be pulled apart by water being forced upward through the wire at these pressure nrps.

Also, the flexing of the grid into a curve of varying desired degree increases the stiffness of the assembly to resist frictional drag of the paper machine wire across the tops of the blades 48. Also at the same time the bowing which is in the direction of travel of the wire, relieves the tendency of the wire to dip into straight spaces between prior art wire contacting surfaces which extend straight across the machine. In other words, by bowing the blades at 48, they present curved lines of contact with the wire and do not run in a continuou straight line across the paper machine.

By placing the grid on the shaker rails, a parallelogram motion is obtained since there will be a differential of motion upon the action of the shaker rails wherein the leading metal strip at will be moving slightly for instance to the left while the rearwardmost one is either moving in the same direction but at a different rate or is actually moving in the opposite direction to a limited degree, and this also improves the uniform formation of the paper on the wrie.

The bowing of the strips 40 and doctors 48 is made possible by the construction of the grid, and especially of the spacer and bolt means for holding the strips. It will be clear that this grid construction allows the flexure required for the bowing action by means of screw shaft 24, and for the shaker rail action described above.

Having thus described my invention and the advantages thereof, 1 do not wish to be limited to the details herein disclosed, otherwise than as set forth in the appended claims, but what I claim is:

1. In combination with a screen wire of a Fourdrinier machine, a doctor supporting said screen, said doctor being provided with a leading narrow edge adapted to unerlie and scrape the bottom surface of the Fourdrinier wire for drainage of water at .the leading edge of the doctor, said doctor extending rearwardly away from the leading edge in the direction of travel of the wire in a gradually relieved surface from said wire, said relieved surface forming a vacuum generation for the discharge of water at the rear of the doctor, said doctor extending in an are having a convex surface facing the direction of motion of the wire.

2. In combination with a screen wire of a Fourdrinier machine, a doctor supporting said wire, said doctor being provided with a narrow leading edge scraping the lower surface of said wire and having a rearwardly-extending relieved portion, said relieved portion forming a vacuum for the discharge of water from said wire, means supporting said doctor, the doctor supporting means being arranged transversely across the Fourdrinier machine and being resilient and semi-flexible and capable of being bowed, said doctor also being bowed therewith, and means to bow the supporting means and thereby the doctor.

3. The combination of claim 2 wherein the means to bow the suppporting means and doctor also holds the same in bowed condition.

4. In combination with a screen wire of a Fourdrinier machine, a doctor supporting said wire, said doctor being provided with a narrow leading edge scraping the lower surface of said wire and having a rearwardly-extending relieved portion, said relieved portion forming a vacuum for the discharge of water from said wire, means supporting said doctor, the doctor supporting means being arranged transversely across the Fourdrinier machine and being resilient and semi-flexible, and means to bow the supporting means and said doctor, said supporting means comprising a resilient strip and including means for bowing said strip outwardly facing the direction of the travel of the wire so that the strip and doctor present a convex aspect to the direction of travel of the wire.

5. In combination with the screen wire of a Fourdrinier machine, a doctor extending generally transversely of said wire underneath the same, said doctor having a leading relatively sharp edge scraping the lower surface of the wire, and a relieved rear edge portion forming a vacuum with the wire, mean supporting said doctor, said supporting means comprising a vertically arranged elongated narrow strip extending generally transversely of the machine, the doctor being provided with a generally centrally located longitudinally arranged vertically extending slot adapted to be received by the upper edge of said strip, said slot being arranged at an angle to said relieved surface and said strip, and means holding said strip in generally vertical relationship to maintain said relieved surface at an angle to the Fourdrinier wire, and means for applying pressure to the ends of said strip and bowing the strip, said strip and said blade being made of flexible material to accommodate the bowing action.

6. A water doctor box for the wire of a Fourdrinier machine comprising a grid-like member, means mounting the same under the w' e generally transversely of the machine, and a series of doctors mounted on said grid-like member, said doctors being generally parallel and closely spaced and each presenting a leading narrow edge for scraping the lower surface of said Fourdrinier wire as it passes thereover, and each doctor being provided with a relieved top surface providing a series of vacuums, one after another, as the wire passes thereover, for drainage of water from the wire down through said grid-like member, said grid-like member comprising in general a series of generally parallel vertically arranged elongated narrow gauge thin metal strips, means spacing the strips, means holding the strips in parallel upright relation extending transversely of the wire, means to how the strips, said doctors being mounted on the strips individually and being bowed therewith.

7. A water doctor box for the wire of a Fourdrinier machine comprising a grid-like member, means mounting the same under the wire generally transversely of the machine, and a series of doctors mounted on said gridlike member, said doctors being generally parallel and closely spaced and each presenting a leading narrow edge for scraping the lower surface of said Fourdrinier wire as it passes thereover, and each doctor being provided with a relieved top surface providing a series of vacuums, one after another, as the wire passes thereover, for drainage of water from the wire down through said grid-like member, spaced elongated bolts extending directly through said doctors, spacing means for the doctors, said bolts being slotted and receiving said spacing means diametrically through the slots, said spacing means being arranged generally at to said doctors and bearings thereon, and means for tightening said spacing means and said doctors into a substantially rigid grid, means located adjacent the ends of said doctor to apply pressure thereto for bowing said doctors while maintaining their general parallel relationship.

References Cited in the file of this patent UNITED STATES PATENTS 1,826,735 Cofrin Oct. 13, 1931 1,859,869 Hadley May 24, 1932 2,170,109 Berry Aug. 22, 1939 2,928,465 Wrist Mar. 15, 1960

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