US3135654A - Stock distributor - Google Patents

Description

June 2, 1964 FAIR 3,135,654

STOCK DISTRIBUTOR Filed July 11, 1962 4 Sheets-Sheet 1 III I, 1",... "IIIIIIIIIIIIIIIIIIII,

INVENTOR. ALBERT E. HAROLD FAIR ATTORNEY.

June 2, 1964 A FA|R STOCK DISTRIBUTOR Filed July 11, 1962 4 Sheets-Sheet 2 j z It n E A q- 9'. N

I N N /8 N z z m INVENTOR. ALBERT E HAROLD FAIR q m ATTORNEY.

June 2, 1964 A. E. H. FAIR 3,135,654

STOCK DISTRIBUTOR Filed July 11, 1962 4 Sheets-Sheet 5 ALBERT E. HAROLD FAIR BY @wm@ ATTORNEY.

June 2, 1964 FAIR 3,135,654

STOCK DISTRIBUTOR Filed July 11, 1962 4 Sheets-Sheet 4 INVENTOR. ALBERT E. HAROLD FAIR ATTORNEY United States Patent 3,135,654 fiTOCK DISTRIEEUTOR Albert E. Harold Fair, 27 Neweli Road, Erookline, Mass. Filed July 11, 1962, Ser. No. 209,136 in claims. (or. 162-336) This invention relates broadly, to the control of a confined stream of an aqueous suspension of papermaking fibers (i.e. a stream of liquid having fibers suspended or dispersed therein), and more particularly comprehends new and useful improvernnts and structural refinements in flow control means for the spreading and quieting of such streams in the stock conduit system of the web-forming machinery.

The control of such a confined stock stream is of great importance in the operation of papermaking machines of various types where it is necessary to deliver the fibercontaining liquid stock from which the paper is manufactured to the Web-forming region of the machine in the form of a wide and relatively shallow flowing stream of rectangular cross-section which may be under considerable pressure.

The method of delivering the stream of papermaking stock to the flow control means envisions the use of a suitable pump, in conjunction with a closed conduit system wherein the confined stock stream is usually circular in outline, so as to necessitate the transformation thereof into a shallow, relatively wide stream which is required at the web-forming region of the papermaking machine.

It is known that to produce a paper sheet having uniform physical properties, the paper stock (which may include water, pulp, fiber, filler, dye, glue, etc.) delivered to the web-forming region should be evenly distributed across the machine width. Expressed mathematically, this means that the kinetic energy and potential energy in unit areas of the stream delivered to the web-forming region should be as uniform as possible throughout the stream cross-section, and in addition, the entire stream should be maintained in a condition which is as near to steady-state flow as it is posisble to obtain. In other words, the stock should be delivered to the web-forming region at a uniform pressure and velocity across the width of the machine, and the pressure and velocity relationship should be invariant with time.

This invention envisions a new and novel stock distributor or flow spreader as a component of the closed conduit system and as a cooperant instrumentality with a new and novel head box and its inclusive interference devices as another component of the closed conduit system, which flow spreader and head box participate in a conjoint result of supplying a single, steady, wide, smooth, thoroughly mixed, uniform stream of the aqueous suspension, free from large eddies, or fiocculations, to the web forming components of the machine.

The objects of the invention are accomplished by the provision of cooperating flow-spreading and quieting means in a conduit system making more positive and more effective the control of a flowing stream of papermaking stock.

It would be indicated, ab initio, that while a machine of the Fourdrinier type is herein disclosed as coacting with the structure of the invention, it is envisioned that cylinder and/or other types of papermaking machines may be employed with equal ease and facility.

It will be helpful to an understanding of the invention first to consider briefly some of the more essential and important features and aspects of the prior art and of the present invention, so that same may be kept in mind during subsequent reading of the detailed description of the practical embodiments of many of my improvements and representative illustrations thereof in the hereunto annexed drawings.

As known, the head box or fiow box delivers to the wire a suspension of fiber and other additives dispersed in a water vehicle, said delivery being at a predetermined velocity through an orifice, commonly called a slice, which extends laterally across the width of the machine, for deposit upon a web-forming means. Such web-forming means, in the case of a Fourdrinier type of machine, comprises a continuously-travelling endless wire, having a generally horizontally-extending run through which, by means including capillary action and surface tension, the Water is drawn so as to leave upon the upper planar surface of the wire a mat or Web of the papermaking fibers.

The desideratum of supplying to each increment of the web-forming area an equal and uniform distribution of fibers, under steady-state flow conditions, in the form of a moving mass of Water and fiber in suspension, with each lamina thereof moving in the machine direction at the same velocity and under such pressure as allows a delivery velocity equal to the speed of the travelling forming wire, is well understood and accepted in the papermaking art, and various flow control arrangements have been suggested and used in an effort to attain these conditions, but such have not been altogether satisfactory.

The factors for attaining the desiratum, heretofore, have been inherently conflicting and notoriously incapable of correlation except at low operating speeds, Wherefore most machine operations have been conducted under compromise conditions.

As if the difficulties in formation were not sufficient in and by themselves, they have been accentuated and aggravated by increases in machine widths and speeds as the papermaking machinery art has developed in its forward progress. As the widths are increased and/or as the speeds are increased, all of the elements and inherent problems are aggravated many times the proportion of such increases. 7 As machine speeds have increased, the use of relatively high flow velocities has been necessitated and the head box has become one of the limiting factors of the machine. To obtain theoretical heads at speeds of 2000 feet/minute and over, the head box has had to be of such height as to be ungainly. To effectively eliminate or cut down the size of the head box, various pressure devices with fiow spreaders or flow eveners have been designed to distribute the stock uniformly across the full machine width at proper velocities and without cross currents and in uniform dispersion.

Disturbingly, a high flow velocity is usually associated with violent currents in the flow direction. In some cases, the desired defiocculation is achieved, but at the expense of creating irregularities across the web, due to uneven streams within the greater mass of fiber suspension. Such lack of uinformity deleteriously alfects the web strength and causes unevenness which interferes with the qualtity of the end product.

It is well known that pulp fibers will flocculate or settle unless agitated or kept in motion or caused by some physical-chemical means to oppose each other, which flocculation will cause a mottled or blotchy formation and which settling will cause a massing of fibers, with the masses breaking away and causing spots in the sheet, and if large enough, breaks at the presses and/or at other points.

This condition presents consistent difficulties to the task of delivering a uniform suspension of fibers to the webforming region, and is aggravated by the problems inherent in avoiding the formation of currents in the suspension.

As to directionality, an absence of parallel flow in the machine direction signifies a presence of cross currents which will cause variations in the quantity of fibers delivered across the lateral width of the forming area, resulting in heavy and light streaks across the formed sheet.

It follows, therefore, that optimum formation depends upon two factors: (1) a uniform flow of the mixture of pulp and water to the web-forming area; and (2) a uniform dispersion of the fibers within the carrying medium.

I am aware of a paucity of suitable instrumentation which has been the stimulus for improvisations in prior art papermaking machines, especially for purposes or" effectuating high speed operation. Until now, no satisfactory flow control system has been forthcoming which so admirably combines, in a simple manner, the multiplicity of desirable features for both low speed and high speed operation.

Relatively complicated countercurrent flow devices have been known. One approach has visualized resort to multiple feeds to the head box by means of small pipes across the machine width, the stock being normally pumped thereto through a single pipe to a manifold having a plurality of outlets leading into the head box, each outlet serving, objectionably, to create its own set of currents or turbulences. Such a plurality of forward currents had led to unequal velocities between the points of flow, not to mention diflicult-to-iron-out dead spots, eddies and fluctuating cross currents.

Numerous supplemental correctional devices have been resorted to, such as perforated boards, adjustable partitions, racks, discs, and the like, to eliminate the created conditions, but notwithstanding various attempts to merge these currents, it has been exceedingly difficult to destroy them altogether, wherefore they persist at the slice.

Also employed have been head boxes with relatively large compartments, resulting in slow flows of stock streams so that the pulp fibers suspended in the carrier become quiet and flocculation and settling occur, leading to a mottled and uneven sheet. It is obviously requisite, therefore, to keep the mass moving at a velocity suflicient to preclude such state of quiet and the resultant flocculation and settling. Efforts in this direction involving the use of a plurality of adjustable partitions have encouraged the forming of longitudinal currents in the head box flow and have allowed an excess of exposed surfaces.

Other systems have incorporated explosion chambers and flow manifolds and turbulence, caused by a sudden flow enlargement or by a quick reversal of flow direction, tends to break up flocculation and to provide additional mixing. Concomitantly, however, it usually allows eddies, spirals and cross currents and induces air entrapment to further disturb formation.

The prior constructions, aimed in various ways to solve the inherent problems, appear consistently to be attended with certain serious disadvantages and limitations which have militated against their more general adoption. In contradistinction, I have discovered that all of these difficulties and disadvantages are overcome and new advantages accrue in the system of the present invention.

I accomplish this by the provision of a structure which comprehends improvements in the stock-receiving component, inclusive of the flow distributor, which converts a flowing stock stream of a certain cross-section to a flowing, yet constantly agitated, stock stream of another crosssection and allows the attainment of a Well and uniformly dispersed mixture having little, if any, forward currents to cause unevenness in the formed web, and further inclusive of the head box, which allows a forward velocity of the suspension, at the point of entry to the pond, which is relatively slower and in better conformation than that allowed in other known types of head boxes and which includes internal agitation means involving the inducement of small organized cross currents to keep the fibers dispersed, and, therefore, amenable to close and uniform web formation, and to equalize the strength of the formed web in both forward and cross directions.

The flow control means of the invention, as aforesaid, has particular relation to the control of a flowing stream of stock, comprising a dispersion or suspension of fibers, Within a conduit system useful for transforming the flowing stock stream as it is discharged to the inflow end of a flow spreader from an inflow conduit of one cross section into a relatively shallow, elongated reetangularlyshaped form as it is delivered from its outflow end with an exact hydraulic balance being attained at all points along the width so as to allow an equal quantity of stock to each unit width of the head box and, in turn, of the slice and of the web-forming elements of the machine.

The flow spreader, as used in the conduit system hereof, comprises essentially a rigid-walled, laterally-diverging conduit adapted to be connected into the system between the fan pump and the web-forming region of the equipment for the purpose of effecting a widening and reduction in depth of the flowing stream. Thereby, a gradual flattening of the round cross-section of the stock stream and a gradual pinching of its central flat area, so as to preclude a concentration of flow at its center, is allowed with a minimization of surface contact, it being well accepted with the greater the surface area which the flowing stream contacts, the greater the hazard.

The flow spreader is generally of fan shape and functions, within a relatively short distance, to transform the flow from the round cross-section to a relatively flat pattern by virtue of the gradual flattening. A mere flattening of the cross-section and no more, would create a more or less slot-shaped outflow adjacent the inflow of the head box resulting in an obviously heavier flow of stock at the center of the outflow than at its edges, the distance through the center being shorter and the friction thereat being less. Contrariwise however, the chamber of my flow spreader is depressed in the area of its midsection, restricting the flow thereat and forcing the flowing stream to be distributed more evenly across the entirety of the width of the inlet to the head box.

The conduit section between the fan pump and the throat or inflow end of the flow spreader will be suitably dimensioned and shaped so as to establish the flowing stream in a substantially steady-state flow condition as it enters the flow spreader.

Additionally, the conduit section between the outflow end of the flow spreader and the head box will be likewise suitably dimensioned and shaped so as to maintain the flow outwardly of the flow spreader in a steadystate condition until it enters the web-forming region.

The configuration of the flow spreader per se is such that the stock stream flowing therethrough is maintained in a substantially steady-state flow condition, such that as it is delivered to its outflow end, it will possess a more uniform pressure across the entirety of its width and a more uniform velocity throughout its cross-sectional area than it would have were the control devices not present.

Cooperatively related to my flow distributor is a head box of a design which advantageously is dimensioned and shaped so as to maintain the flow outwardly of the flow spreader in a steady-state condition until it enters the web forming region, while with the aid of interference devices, simultaneously creating small intermittent and organized cross currents so as to destroy the normally-present fluctuating longitudinal currents.

The attainment of more thorough fiber dispersion allows the increasing of the percentage of fibers in suspension, thereby allowing a reduction in the percentage of carrier used, which in turn reduces the amount of carrier subsequently to be removed, all permitting higher operating speeds, greater production rates, and substantial savings in power used for pumping the suspension to the web forming components.

Within the head box, a slowing of the flow ensues by the use of a gradually enlarging first pass as the flow approaches an adjustable dam, which means aid in mainraining an even flow of fiber suspension at a reduced velocity wherefor uneven currents are precluded and a relatively placid pond results.

Due to the fact that such slowing will allow flocculation, it is necessary to provide agitation to deflocculate the suspension and simultaneously to prevent the formation of substantial currents in the mixture of water and solids and same is accomplished herein by agitator means which are designed to turn at variable speeds to suit the grades of paper and machine speeds being run.

Conceivably, installation of the structure hereof may be made in a head box of the closed inlet or pressure type, its advantage in such instance being readily appreciated when it is recognized that the proper functioning of such types of head boxes is absolutely dependent upon a proper flow to the nozzle. With a closed inlet or pressure type head box, it is diflicult to correct unevenness of flow other than by adjustment of the slice lip, which adjustment may cause streaks in the flow on the wire. The system hereof superbly overcomes this difliculty.

When applied to a cylinder machine vat, the structure hereof may be placed under the vat and the discharge end connected to the vat by a suitable connecting fitting of full vat width, the discharge velocity from the flow spreader being reduced either in the connecting fitting or in approach passages in the vat and before release into the open end pond at the forming point so as to prevent turbulence. The agitation means of the structure may be applied in the chamber immediately before the inlet to the vat.

Before proceeding further, a consideration of the phenomenon of separation is indicated. Such frequently occurs within a stream of stock flowing through a closed conduit when it loses energy because of frictional contact with the conduit walls, which loss is evidenced by a reduction in the velocity of the stock stream adjacent said conduit Walls. The velocity of the fluid is zero, or near zero, at the walls of the conduit and increases rapidly in a direction inwardly from the walls until it attains free stream velocity (i.e. the velocity of the stock stream whose energy is unaffected by the presence of the conduit walls). In a narrow region adjacent the wall, the fluid moves at a velocity which is slower than its free stream velocity and such is generally referred to as the boundary of the stock stream. Where the stock stream suddenly moves into an area of higher pressure (when it moves into a section of greatly increasing cross-sectional area) the fluid in the boundary layer of the moving stock stream may not possess suflicient energy to overcome the higher pressure which it encounters, and in such instance, the dead or low energy fluid is forced to stop and may even actually flow in a reverse direction, thus separating from the main fluid stream and initiating vortex formation at the separation point.

I have determined that this separation may be prevented by gradually pinching the central portion of the ever-widening cross-sectional area of the stock stream so as to divert increasing portions of the flow toward the side walls of the flow spreader so as to accomplish the removal of the low energy fluid from the boundary layer of the stream at any point where the boundary layer is about to separate from the main stream.

Removal of the low energy fluid from the boundary layer of the stream may allow a new boundary layer to start to form downstream thereof. Instarting to form, such boundary layer will possess enough energy to move downstream for some distance before it loses sufi'icient energy by frictional contact with the side walls to separate from the main stream and by such time, still further increasing quantities or portions of the flow have been diverted toward the side walls wherefor separation of the newly-forming boundary layer, as it is about to separate from the main stream, is precluded.

By suitably dimensioning the pinching of the walls of the flow spreader, one is able to completely eliminate the 6 phenomenon of separation and the resulting eddy formation in the fluid stream.

The physical embodiments here described will be indicative of but two of the multiplicity of ways in and purposes for which the principle of the invention may be employed. It will be apparent, however, that the specific physical embodiments delineated, albeit the preferred eX- emplifications, are only indicative of but two of the multiplicity of ways in and purposes for which the principles of the invention may be employed, said embodiments not being intended to be exhaustive of, nor limiting of, the spirit or scope hereof. On the contrary, they are merely exemplary and explanatory for the purpose of illustrating the invention that others skilled in the art to which the invention pertains, may so fully understand the invention, its principles, and the applications thereof, that they may embody and adapt them in numerous forms, each as may be best suited to the conditions and requirements of any particular use.

The invention will be better understood from a consideration of the detailed description which follows, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a broken side elevational view of a stock distributor or flow spreader and flow box, as viewed from the front side thereof, with certain components being shown in section;

FIG. 2 is a small-scale sectional elevational view of the stock distributor or flow spreader, as viewed from the left hand end shown in FIG. 1, the flow box per se and other parts of the machine having been omitted in the interests of clarity;

FIG. 3A is an enlarged, greatly exaggerated sectional view at the line 3A3A of FIG. 2 showing one extreme degree of relationship of certain walls of the structure; FIG. 3B is a view similar to FIG. 3A showing an opposite extreme degree of relationship of certain walls of the structure;

FIG. 4 is a fragmentary elevational view of one of the agitating rolls of the invention;

FIG. 5 is a sectional view on the line 55 of FIG. 4;

FIG. 6 is a broken side elevational view of a modified form of a stock distributor or flow spreader and inlet box, as viewed from the front side thereof, with certain components being shown in section; and

FIG. 7 is a broken top plan view, in smaller scale, of the modified form of the stock distributor or flow spreader shown in FIG. 6, with certain parts being shown in section.

In the following description and in the appended claims, various components and details thereof will be identified by specific names for purposes of convenience. Such phraseology and terminology is for the purpose of description and not of limitation, the expressions. being employed in a generic and descriptive sense only.

With continued reference now to the drawings, which illustrate typical and preferred embodiments of the invention for purposes of disclosure, I have shown, in FIG. 1, the outflow end of a delivery section comprising a first or inflow conduit, generally indicated by reference numeral 10, directing a flow of stock to a second conduit or flow spreader, sometimes identified as a stock distributor or approach chamber, generally indicated by reference numeral 12, same accommodating the stock in its flow toward and into a head box or flow box, generally indicated by reference numeral 14, mounted adjacent the path of movement of the Fourdrinier wire in known manner.

The exact form of stock distributor and head box employed will be variable to meet individual mill requirements, some mills having a basement or lower level to allow the disposition of certain equipment below the general horizontal plane of the papermaking machine, and others requiring all appurtenant equipment to be disposed above the machine room floor.

The fiow to head box 14, by means of a conventional pumping mechanism, not shown, is from a supply point, also not shown, through first or inflow conduit 10 comprising a feeder pipe 18 of circular cross section having an exit terminal or outflow suitably joined to a pipe connection 2d of flow distributor 12 as by means of coupled complementary flanges 22 and 24-, as shown. Said pipe connection 25}, also of circular cross section, leads directly to the inlet or inflow of flow spreader 12.

Conveniently, the opening of the inlet or inflow end is circular though it may be square or rectangular or otherwise to accommodate itself to the particular configuration which the inflow conduit may partake of.

The orifice at the slice being essentially in the form of a rectangle, it is my desideratum to convert the flow from the round cross section of feeder pipe 18 to a rectangular cross section by the fiow spreading system now to be described.

As shown in FIGS. l3B, flow spreader 12 essentially is of a fan or fish-tail configuration having a main axis extending in a generally vertical plane and will be seen to comprise vertically-extending rear and front walls 3t) and 32 respectively, which walls generally converge toward each other from their lower to their upper extremities, and a pair of oppositely-spaced outwardly-inclined ide walls 34, each having opposite rounded side edges merging smoothly with the respective adjacent side edges of said rear and front walls, the well rounded construction permitting the most effective removal of the low energy fluid from the boundary layer of the stock stream, the surface curvatures desirably following the stream lines of the llow in these regions, so as to lend value in the attainment of steady-state flow at and forward of the flow spreader outflow or outlet.

Said lowermost edges of walls 30 and 32, and the lowermost edges of the side walls 34, 34 merging therewith, define a point of fiber suspension entry or inflow or throat into the fiow spreader proper and the pipe connection is suitably connected thereto in any known and conventional manner.

The upper extremities of said walls 30, 32, 34 and 34 define the mouth or outflow or point of stock discharge from the flow spreader.

Each of the walls 30 and 32 converges inwardly from its opposite side edges towards its own vertical center line, with the degree of convergence increasing gradually from the lowermost edge of the wall to the uppermost edge thereof so as to allow a gradual pinching eifect thereat.

As will be observed by a comparison of FIGS. 3A and 3B, the degree of convergence along the uppermost edges of said walls may be within a range of a minimum of 2, as shown in FIG. 3A and a maximum of 30, as shown in FIG. 3B.

As previously mentioned, the major axes of the rear and front walls 30 and 32 are additionally so related that each generally converges toward the other at its uppermost extremity so as to provide therewithin a chamber which gradually narrows in depth (as contrasted with width) from its lowermost area towards its uppermost area so as to allow a gradually increasing resistance to flow in the passageway formed therebetween.

Such convergence of the general axes of the walls 30 and 32, coupled with the inward depression or pinching of each wall toward its own center line, achieves an effect which forces the suspension to spread out toward the sides of the conduit rather than to tend to concentrate centrally thereof, as would be the case were the resistance to flow not so slightly increased at the midseetion of the chamber and/or the midsection of the stream flow.

By such flow spreader structure, the stock is constrained to flow vertically upwardly through a defined fan-shaped flow chamber, the chamber having an ever-widening sideto-side dimension or width, and an ever-thinning frontto-back dimension or thickness, with the thickness, at the upper extremity or exit or mouth, centrally of the width, being less than the thickness at the upper extremity at the side edges.

By such design, the flow spreader demonstrates a capacity for gradually and progressively converting a flow of circular cross section upon entry thereinto into a constantly widening and thinning stream which has assumed a flow of generally rectangular cross section upon discharge therefrom, it being understood that the widthwise dimension of the flow stream at the upper extremity or mouth will correspond substantially to the lateral width of the associated head box component subsequently to be described and width of the papermaking machine toward which the fiow is directed.

The separation and resultant eddying and vortex formation which occurs along the inner faces of the diverging walls 34, 34 are eliminated by the addition to the fluid of the boundary layer by means of the pinching of the walls 30 and 32 forcing quantities of the fluid from the center of the stream toward those points where separation would normally occur. The added energy is thus discharged into the boundary layer in the form of added fluid from the main flow stream and imparts added momentums to the fluid of the boundary layer, making it possible for the boundary layer to overcome the adverse pressure gradient which it encounters in its flow path for some distance beyond the point where the energy is added. In essence the quantities of fluid, defined as added energy, while they may be added at points along the diverging walls, the points are so large in number and so close together as to form a continuous line along the inner face of each diverging wall 34, 34.

Stated otherwise, the fiber suspension passes through the delivery section 10 from the source of stock supply and is transformed from its flow of circular cross section to a flow of ever-widening relatively fiat cross section within the flow spreader, all so as to contribute to the general purpose of precluding the development of uneven stock conditions at the web-forming area.

Of course, it will be understood that the flow spreader may be operated in a horizontal or angular disposition as well as in the illustrated vertical position. One so horizontally disposed is hereinafter described and shown in connection with FIGS. 6 and '7.

As known, a head box functions to deliver stock to the slice at the proper velocity, thoroughly and uniformly mixed, and free from cross currents, turbulence and eddies.

A large quiet head box will eliminate currents but such allows the fibers expression of their tendency to coagulate. A smooth flow at relatively slow speed, with the fibers at rest relative to one another, is known to allow conditions that promote flocculation, slime formation, and stock accumulation in the dead spots.

Contrariwise, a strong agitation, while mixing the fibers thoroughly and dispersing them will create the very objectionable cross currents and eddies I seek to avoid.

The head box design hereof, accordingly, is a compromise between the two extremes and comprehends interference devices to promote the required agitation so as to disperse the fibers.

The head box, now to be described, fulfills admirably the desiderata of:

(l) Allowing no surging at its entrance (2) Allowing no dead areas therewithin (3) Allowing no corners or sharp angles (4) Allowing a uniform delivery to the slice (5) Maintaining a uniform, homogeneous fiber disper- (6) Eliminating entrained air (7) Precluding fiber flocculation The flow box or head box per se comprehends transversely-spaced vertically-extending side walls 40 and 40 and interconnected transversely-spaced vertically-extending forward and rearward end walls 42 and 44 respectively and a bottom wall 46 to define a pond therewithin.

As is conventional, a slice, generally indicated by 48, is provided, the stock and water flowing from the head box through the slice, said slice having the primary function to deliver a sheet of liquid of uniform thickness and equal velocity across the width of the web-forming instrumentalities.

As known, a paper machine slice is essentially an orifice and may be of any of several basic types.

Purely for illustrative purposes, same not forming a part of the invention, I have here shown a Voith type of slice, it being one of the earliest type slices incorporated into higher speed machines and of a design to allow a raising or lowering of a top lip 50 in relation to a bottom lip 52, for maintaining a constant head above the wire 54 and still increasing the quantity of flow through the slice.

Explanitorily, the operation of a paper machine for a grade or type of paper must be such as to deliver a constant amount of fibers at all times. The amount of water accompanying the fiber onto the web-forming elements may be varied to improve the formation or change the qualities of the finished sheet. In other words, the consistency (pounds of fiber/pounds of water) in the head box can be varied and the adjustment of the top lip of the slice will allow a constant head to be maintained. For example, if the machine tender wishes to reduce the head box consistency by adding more water, he can raise the top slice lip, increase the opening, and still maintain the head.

Small hand wheels 56 suitably supported on the wall 42 are spaced across the width of the top slice lip 50 and related spindles 57 provide a means for leveling the slice and providing uniform flow from one edge of the wide width to the other.

In known manner, a breast roll 58 is disposed adjacent the forward end of wall 46 and the endless wire 54 is entrained therearound as well as other components not shown.

A baffle, which may be formed from a generally vertically and upwardly-extending wall 60, may be, if desired, doubled upon itself to provide a secondary wall 62, and is spaced inwardly of flow box rear wall 44 to provide an upwardly extending first pass or passageway 64 defined by said walls 44 and 60 and the head box side walls 40 and 4h.

The lower extremities of walls 44 and 60 will converge slightly so as to merge smoothly with and be jointed to the upper extremities of respective fiow spreader walls 30 and 32 and the lower extremities of respective flow spreader walls 34 and 34 in the accomplishment of the provision of a head box entry which allows no surging thereat.

The said first pass 64 will thus be observed to comprise a slowly enlarging passageway for the upward flow of the stock, which upward flow will allow the elimination of air from the stock and will efiectuate a general slowing of the stock flow.

A downwardly-extending plate or vertical slice 66 is adjustably associated with headbox side walls 40, 40 and is vertically aligned with wall 60 to provide a variable opening 68 therebetween.

The adjustment means for said plate 66 is not shown and may partake of any suitable and conventional design. It will be appreciated that wall 60 functions as a dam over which the stock flows, which dam assists in maintaining an even flow of fiber suspension at a reduced velocity wherefor uneven currents are precluded.

Said wall 6i? constitutes but one of the interference devices within the head box to promote the required agitation for preventing floc formation.

A downwardly extending baflie wall 70 is spaced from and forwardly of wall as in substantial parallelism therewith to provide passageway 72 therebetween allowing the downward flow of the stock therethrough.

By such baffle means and the related bafiie 64?, it Will be appreciated that the flow of the stock and water is confined between the battles and is thus controlled so that the erratic circulation found in large boxes is virtually eliminated.

Wall 7%) provides a restricted opening '71 defined by the space above lower wall 46, and by such restriction, the flow is slowed down to a considerably reduced rate of forward flow when it moves therethrough.

Forwardly of Wall 70, bottom wall 46 is inclined upwardly to provide another passageway 74 of gradually increasing transverse depth as contrasted with the lateral widthwise dimension, which dimension remains stationary.

It will be thus appreciated that walls 60 and 70 consttiute one set of interference devices within the head box for promoting the required agitation to prevent floc formation.

During the flow through third pass 74, the suspension is subjected to agitation and mixing by a plurality of agitating units, each generally indicated by numeral 80.

The agitators generally comprehend an arrangement and operation of a plurality of agitating units disposed in manner to keep the pond alive, to eliminate flocking, to destroy objectionable currents, and to better prepare the stock for delivery through the slice to the forming wire or mold under controlled conditions of uniform velocity flow.

Basically, by such agitating units, I provide means whereby the stock stream meets identical resistance across its entire width and is evenly fed to the forming surface at a single, selected velocity. Simultaneously therewith, I cure other specific prior art defects inclusive of the formation of light and heavy streaks running in the machine direction at regular or varying spaced intervals across the machine width by the deliberate and intentional creation of a pattern of a multiplicity of minute cross currents for effecting improved random dispersion of the fibers.

As known, a momentary speed increase followed by a sudden speed decrease creates small eddy currents which break up fiber fiocs. Pin racks, perforated plates and rolls have all been heretofore used for this purpose.

The agitating units hereof effectuate a reduction in area through which the fluid flows.

At the point of reduced area, the stock velocity is increased and upon moving past the agitating unit, the velocity of stock and water is again decreased.

Each said agitating unit may comprise a longitudinally-extending rotatable cylindrical shell or tube 82 with outwardly-projecting solid trunnions 84 at opposite ends of said shell for insertion through the respective adjacent side wall of the head box in suitable journal or bearing means mounted in said side walls whereby the agitating unit may be positioned between and intercoupled with the confining opposite head box side walls in close running relationship therewith.

Understandably, as an alternative construction, shell 82 may be sleeved upon a longitudinally-extending rotatable control or roll shaft and supported radially outwardly thereof in concentric manner as by a plurality of spiders, said control or roll shaft being journalled at its opposite ends in the adjacent head box side walls.

On the outer peripheral surface of shell 82, a multiplic ity of radially-arranged outwardly-extending fins or vanes 86 are stationarily secured, each fin or vane being disposed angularly or obliquely relative to the longitudinal axis of the shell.

The fins are grouped as groupments or sets, the fins of each groupment or set being arranged in a longitudinallyextending row in equi-spaced distance from each other Eli and parallel relationship as to of the row being parallel to the longitudinal axis of shell.

The fins of a groupment or set divide the surface area of the shell along the axis thereof as defined by said groupment or set into a plurality of substantially equal segmental sections. By virtue of the oblique disposition of the adjacent fins, the planes of the fins of one row intersect the planes of the fins of a next adjacent row. The angle of fin disposition should not exceed 30 and, for best results, should be within the range of l25 relative to the longitudinal axis of the shell.

The fins of one set in one row and the fins of another set in the adjacent row are disposed in angularly intersecting planes as the shell is rotated.

The rows, there being 4 in number in the illustrated embodiment, are equidistant from each other, they being disposed approximately 90 from each other, though it will be understood that the number of rows can be varied so that the angle therebetween may be greater than or less than said 90 As to their angular or oblique disposition, the fins of adjacent rows are alternately disposed to effectuate the reversing of cross currents which serve to mix the stock and to reorient the fibers so that many of them will have their longitudinal axes at right, or approximately right, angles to the direction of flow instead of being aligned with the flow, as is normal, thereby serving to tend to equalize directional strength and to aid in the formation of the web.

Further as to their angular or oblique disposition, the fins of one axial row may be arranged at a certain angle relative to the shell longitudinal axis, and the fins of the next adjacent axial rows are preferentially, though not obligatorily, arranged at an angle opposed to the said certain angle in the said one axial row for purposes of eflectuating, upon the shell rotation, opposing sets of miniature or localized cross currents in the sense that the set of miniature or localized cross currents enduced by the said one axial row are opposed by the set of miniature or localized cross currents enduced by the said adjacent axial row to allow a wobbling or back-and-forth movement, on which is repeated over and over as the shell is rotated. Thereby a shearing action results which causes the stock to be deflected first in one direction and then in the opposite direction so as to allow complete overlapping and intermingling before delivery to the forming pond, simultaneously avoiding stock flocculation and minimizing the development of erratic eddy currents and other non-uniform flow conditions.

Stated otherwise, the adjacent rows function to establish a wobbling or constantly changing movement in the flow of the stock stream flowing therepast, to the end that the assemblage functions as an improved means for insuring more random distribution of the fibers.

The agitating units will extends transversely of the path of stock flow through the box and in spaced relation to its discharge outlet adjacent the forming medium so as to perform a passive direction or redirection of the flow.

A rotative movement is imparted to each agitating unit by a power means, not shown. Preferably, the rolls are rotated in the same direction and in timed relation to the rate of flow though they may be rotated in opposite directions, if desired, and/ or at varying rates of speed so that they are rotated either in unison or out of unison and at constant or at variable speeds.

As the shell is rotated within a single cycle of 360 of rotation, the fins present segments of mutating planes relative to the axis of the shell so as to create the said wobble action by impelling the stock first in one direction and then in another whereby the flow is transversely broken into a plurality of very fine cross currents. The fins rotate to impart a wobble effect to the streams, as they flow between the fins and then flow into and merge with adjacent eddies to effect the ultimate desired intereach other, with the axis the 12 weaving and uniform fiber distribution in the sheet formation. By such rotative movement, the shive problem wherein the fibers tend to deposit and to string on the fins and the shell is solved.

It is contemplated that both the pitch and the dimensions of the fins may be varied to satisfy specific requirements of use, and further that the shell and fin assemblage may be used as a single unit, or that a plurality of such assemblages may be cooperatively employed in a stacked or tandem or in an arcuately-arranged relationship.

As the fins are rotated within a 360 cycle, they circumscribe a wobbling effect as they each rotate about a point defining the center of the shell. Being so mounted, they produce a fine pattern of rapidly recurring and reversing currents. That is, they present segments of mutating planes so as to impart an oscillatory motion to the streams of stock passing therebetween and thereby effectuate the random distribution of the fibers uniformly and evenly at all points throughout the length of the roll as the converging streams intermingle upon having passed between the fins on the roll.

As shown, a single lowermost agitating unit is disposed in the narrow, lower area of pass 74 and serves to insure good agitation, to overcome stagnation, and to offset the tendency of the stock to hug the bottom wall, it being especially well suited for certain grades of paper such as the heavy, slow running grades.

Spaced upwardly thereabove, a pair of agitating units 30 are disposed in alignment as to each other in a plane angularly related to the horizontal axis of the stock in the pond thereabove.

As shown, one agitating unit may be disposed slightly behind the other so that the flow will meet resistance in the shorter path and avoid a tendency to short circuit the wide path to the slice pond.

After entering the head box at the throat of minimum cross sectional area, the suspension flows upwardly into the first pass 64 of the head box and flows transversely outwardly from said first pass through opening 68 into second pass 72 and thence downwardly and beneath wall 71 into third pass 74.

From third pass 74, the stock flows into the pond. The flow therein being upward at a relatively slow rate, the elimination of other air entrapped in the stock is permitted.

From the pond, the stock flows directly through the slice aforedescribed.

I show a modified embodiment form in construction in FIGS. 6 and 7 for purposes of further disclosure, same comprehending a delivery section comprising a conduit or feeder 118 of round cross sectional area directing a flow of stock to a second conduit or flow spreader or stock distributor, generally indicated by reference numeral 112, of relatively flat cross sectional area, same accommodating the fiow of stock into a head box of flow box, generally indicated by reference numeral 114, mounted adjacent the path of movement of the Fourdrinier wire in known manner.

The flow to head box 114 by conventional pumping means (not shown) is from a supply point (also not shown) through feeder pipe 118 of circular cross section to the inlet of flow spreader 112.

The orifice at the slice being in the form of a rectangle, it is a desideratum to convert the flow from the round cross section of the feeder pipe to rectangular cross section.

Flow spreader 112 is of the fan or fish-tail type having a main axis extending in this modification in a generally horizontal plane and will be seen to comprise horizontally-extending upper and lower walls and 132 respectively, which walls generally converge toward each other from their entry to their discharge extremities, and a pair of oppositely-spaced outwardly diverging side walls 134 each having opposite rounded side edges merging smoothly with the respective adjacent side edges of said 13 upper and lower walls, thereby to form an enclosed fanshaped flow chamber.

Said walls 130 and 132 are each of greater width at their discharge ends than at their entry ends so as to provide the aforesaid fan shaped effect, flaring outwardly equidistantly from opposite sides of the center line of the entry edges of said walls 130 and 132, which entry edges define the point of fiber suspension or stock entry into the fiowspreader. The discharge edges of said walls define the point of fiber suspension or stock discharge therefrom.

Additionally, said walls 130 and 132 are converged towards each other, more or less at their midsections, so as to further define therewithin a chamber which narrows in depth (as contrasted with width) from its entry extremity towards its discharge extremity, wherefore the throat at the discharge end presents more resistance to the flow and forces the suspension to spread out toward the sides of the chamber rather than concentrate in the center thereof, were resistance to flow not so slightly increased at said center.

By such modified flow spreader structure, the stock is constrained to flow horizontally-forwardly through the fan-shaped flow chamber defining an ever-widening sideto-side dimension or width in combination with an everthinning top-to-bottom dimension or thickness, with the thickness at the exit extremity or mouth centrally of the width being less than the thickness at the exit extremity at the side edges.

The width of the exit extremity will correspond to the lateral width of the associated head box and the machine width.

Here again, it will be observed that the flow spreader has widened the rectangular section progressively and gradually to the full width of the machine with a corresponding reduction in depth wherefor the stock flows therein in a constantly widening and thinner stream and flows outwardly therefrom to the related components.

The spreading length is according to the width of the flow inlet and the width of the flow box and the spreading angle is within limits that will permit uniform spreading of the flow.

Stated otherwise, the fiber suspension is transformed from its flow of circular cross section to a flow of relatively fiat cross section within the flow spreader and is spread evenly Widthwise of the machine so as to preclude the development of uneven stock conditions at the web forming area.

The flow box or head box per se comprehends transversely-spaced vertically-extending side walls 140 and interconnected transversely-spaced vertically-extending forward and rearward end walls 142 and 144 respectively and a bottom wall 146 to define a pond therewithin.

A breast roll 158 is disposed adjacent the forward end of bottom wall 146 and an endless wire 154 is supported by said breast roll in known manner.

A slice 148 is provided above breast roll 158 and may be of conventional design.

Wall 144 will be provided adjacent its lower end with an arcuate outwardly-curved portion 145 extending transversely of its width to provide an enlarged throat Within the head box and will have a substantially horizontallyextending portion 147 at its lowermost extremity, which with a lowermost extremity 149 of bottom wall 146 will serve to provide a mouth of generally rectangular cross section which may be suitably connected to the exit extremities of the respective flow spreader walls 130 and 132.

Similarly walls 140 will be provided with appropriately configured extensions 141 to be connected to the respective side walls 134 of the flow spreader.

Side walls 140, 140, rear wall 146, and forward wall 144 define a passageway 174 within the head box, said passageway forming an ever-widening approach to the pond, same being accomplished by the upward inclina- 14 tion of wall 146 so that passageway 174 is of gradually increasing transverse dimension.

- During the flow of stock to and through the pass 174, the suspension is subjected to agitation and mixing by a plurality of agitating units or rectifying rolls and 180 which further aid in the means for improving fiber formation in paper as the stock is directed toward the moving forming surface for deposit thereupon.

Each said agitating unit being similar in design and function to that previously described, it does not appear necessary to define it further.

In this embodiment, one such agitating unit 180' is disposed in the sump-like portion provided at the base of wall in order that the stock entering the head box from the flow spreader 134 may be subjected to direct agitation before it enters the passageway 174.

Three such agitating units are disposed in the passageway 174 and are disclosed as disposed in a plane angularly related to the horizontal axis of the stock in the pond thereabove, three being illustrated to emphasize that the invention need not be limited to two such agitating units disposed in a plane angularly related to the horizontal axis of the stock, as in the embodiment of FIG. 1.

By employing one such agitating unit 180 at the inlet to the head box 114, and by employing a multiplicity of such units 180 in the head box proper, the agitating action is spread over the entirety of the area within the pass 174 and the pattern of fine currents created by the agitat ing rolls 180 and 130' is spread out and said currents overlap each other to a degree so as to allow improved uniformity.

All prior art head box designs have one feature in common; the rectifying rolls thereof, whether stacked longitudinally with respect to the flow or otherwise do not effectively destroy the longitudinal flow patterns.

Herein, I provide an agitating unit at the head box inlet and I stack agitating units within the head box transversely of the flow so as to effectuate a breaking in the pattern at every one-quarter turn of each said unit.

The rate of turning contemplated is within a ratio of 2:1 and 10:1, relative to the rate of flow past the agitators, all so as to effectuate a continuous and repetitive pattern of small cross currents.

It is believed that the gist of the invention will be clearly understood from the foregoing disclosure and accordingly, further analysis thereof at this point is considered unnecessary, as I have in accordance with the provisions of the patent statutes, described the construction and principle of operation of my invention together with the apparatus which I believe to represent one of the best embodiments thereof, to the end that others can, by applying current knowledge, readily adapt it for various applications without omitting features which, from the standpoint of prior art, fairly constitute essential char acteristics of its generic and/or specific aspects.

The claims are desired to include within the scope thereof all of said suitable variations, modifications and equival nts by which substantially the results of the invention may be obtained through the use of substantially the same or equivalent devices or means. Accordingly, limitation hereof should only be made as determined by a proper interpretation of the prior art and the scope of the subjoined claims, in which it is my intention to claim all novelty inherent herein as broadly as possible.

Having thus described my invention in an exemplary embodiment, what I therefore particularly point out and distinctly claim as new and desired to secure by Letters Patent is:

1. In fiow control apparatus of the class described, a laterally-diverging conduit for containing a flowing stream of fluid, said laterally-diverging conduit increasing in width from its inflow to its outflow and decreasing in depth from its inflow to its outflow and decreasing in depth along its centerline at a greater rate than in portions at either side of its centerline to form a pinched area along the centerline for diverting portions of the flowing stream toward the laterally-diverging areas and facilitating removal of the lower energy fluid from adjacent the walls defining the laterally-diverging areas in eflectuating maintenance of the fluid thereat in a substantially steady-state flow condition and providing the fluid with a more uniform velocity distribution across the width of the widened stream at the outflow.

2. In flow control apparatus for eflectuating maintenance of a flowing stream of fluid in a substantially cad -state flow condition and providing the fluid with a more uniform velocity distribution across the width of the stream upon discharge therefrom comprising a laterally-diverging conduit for containing the fluid stream, said lateraliy-diverging conduit having an increasing width and a decreasing depth between inlet and outlet and a depth longitudinally of its centerline decreasing to a greater degree than in portions on opposite sides of the centerline for forming a pinched space longitudinally of the center line and diverting portions of the flowing stream toward the laterally-diverging areas and facilitating removal of the lower energy fluid from adjacent the portions of the walls defining the laterally-diverging areas.

3. in flow control apparatus of the class described, a laterally-diverging conduit for containing a flowing stream of fluid and transforming an inflow of circular cross-section to an outflow of generally rectangular cross-section and having diverging side walls and converging opposite walls for directing a controlled amount of fluid from the longitudinal midsection toward the diverging side walls for effecting increases in the average kinetic energy of portions of the fluid flowing within and adjacent the diverging side walls said conduit being further characterized by an increase in width from inflow to outflow and a decrease in depth from inflow to outflow and a decrease in depth along the centerline at a greater degree than in portions on the opposite sides thereof.

4. In a papermaking machine, the improvement in a stock distributing means for converting a flowing stream of an aqueous suspension of paperrnaking fibers from a circular cross-section into a flattened cross-section preliminary to discharge into a head box comprising, an inflow of circular cross-section connected to a source of stock supply, an outflow of generally rectangular crosssection connected to a head box, a wall defining a main body interconnecting said inflow and outflow and gradually increasing in lateral width in fan-like manner from said inflow to said outflow and gradually decreasing in depth from said inflow to said outflow and gradually decreasing in depth along the centerline thereof in greater degree than in portions on opposite sides of the centerline.

5. In a papermaking machine, a stock distributing means for converting a flowing stream of an aqueous suspension of papermaking fibers from a circular cross-section into a flattened cross-section preliminary to discharge into a head box and including, a conduit having an inlet of circular cross-section connected to a source of stock supply and an outlet of generally rectangular cross-section discharging into the head box, said conduit gradually increasing in width and decreasing in depth in fan-like manner from the inlet to the outlet, the width of the outlet being substantially the width of the head box, said conduit decreasing in depth along the longitudinal centerline thereof to a greater degree than in areas on opposite sides of the centerline whereby the stock is transformed from a confined stream of circular cross-section into a shallow relatively-wide stream of generally rectangular crosssection.

6. in a papermalting machine, in combination, a stock distributing member for converting a flowing stream of an aqueous suspension of paperrnaking fibers from a circular cross section into a flattened cross section, a head box connected to and taking delivery of the flow stream from said stock distributing member, said stock distributto ing member comprising a fan-shaped conduit having an inlet end of circular cross section connected to a source of supply and an outlet end of generally rectangular cross section discharging into said head box substantially the entire width thereof and increasing in Width and decreasing in depth from the inlet end to the outlet end and decreasing in depth along its centerline at a greater rate than in portions on either side of the centerline wherewith the flow stream discharges evenly and at a uniform velocity across the entire outlet end and into said head box.

7. In a papermaking machine as set forth in claim 6 wherein said stock distributing means includes verticallyextending front and rear walls generally converging toward each other from their lower to their upper extremities, and a pair of oppositely-spaced outwardly-inclined side walls having rounded side edges merging with the adjacent side edges of said front and rear walls, thereby to form an enclosed fan-shaped chamber.

8. In a papermaking machine, a stock distributing means for converting a flowing stream of an aqueous suspension of paperrnaking fibers from a circular cross section into a flattened cross section preliminary to discharge into a head box comprising, delivery conduit means having an inlet end of circular cross section connected to a source of stock supply and having an outlet end of generally rectangular cross section discharging into the head box, said conduit increasing in lateral width and decreasing in transverse depth from said inlet end to said outlet end, the lateral width of said outlet end being substantially the width of the head box, said conduit decreasing in depth along its centerline to a greater degree than in portions on opposite sides of the centerline.

9. In a papermaking machine, a stock distributing conduit for converting a flowing stream of an aqueous suspension of paperrnaking fibers from a circular cross section at its inflow into a flattened generally rectangular cross-section at its outflow preliminary to discharge into a head box comprising, delivery conduit means having an outflow of circular cross section connected to a source of stock supply and communicating with the conduit inflow, said conduit increasing in width in fan-like manner from the conduit inflow to the conduit outflow with the width of said outflow being substantially the width of the head box and decreasing in depth from said inflow to said outflow and decreasing in depth along its centerline to a greater degree than in portions on either side of the centerline.

10. In flow control apparatus of the class described, a laterally-diverging conduit of generally expanding crosssectional area for containing a flowing stream of fluid, said laterally-diverging conduit having a greater crosssectional area at its outflow than at its inflow by virtue of a width increasing from inflow to outflow and a depth decreasing from inflow to outflow and a depth decreasing along its centerline to a greater degree than in portions on opposite sides of the centerline for eflectuating diversion of increasing portions of the fluid stream toward the laterally-diverging areas in quantities sufficient to effect removal of the lower energy fluid in the maintenance of the fluid in a substantially steady-state flow condition therewitln'n with a uniform velocity distribution across the width of the widened stream at the outflow.

References Cited in the file of this patent UNITED STATES PATENTS 1,707,375 Upson Apr. 2, 1929 2,465,445 Goldsmith Mar. 29, 1949 2,788,719 Bennett Apr. 16, 1957 2,865,260 Lee Dec. 23, 1958 FOREIGN PATENTS 440,431 Great Britain Dec. 30, 1.935

874,698 Germany Apr. 27, 1953

Claims (1)

1. IN FLOW CONTROL APPARATUS OF THE CLASS DESCRIBED, A LATERALLY-DIVERGING CONDUIT FOR CONTAINING A FLOWING STREAM OF FLUID, SAID LATERALLY-DIVERGING CONDUIT INCREASING IN WIDTH FROM ITS INFLOW TO ITS OUTFLOW AND DECREASING IN DEPTH FROM ITS INFLOW TO ITS OUTFLOW AND DECREASING IN DEPTH ALONG ITS CENTERLINE AT A GREATER RATE THAN IN PORTIONS AT EITHER SIDE OF ITS CENTERLINE TO FORM A PINCHED AREA ALONG THE CENTERLINE FOR DIVERTING PORTIONS OF THE FLOWING STREAM TOWARD THE LATERALLY-DIVERGING AREAS AND FACILITATING REMOVAL OF THE LOWER ENERGY FLUID FROM ADJACENT THE WALLS DEFINING THE LATERALLY-DIVERGING AREAS IN EFFECTUATING MAINTENANCE OF THE FLUID THEREAT IN A SUBSTANTIALLY STEADY-STATE FLOW CONDITION AND PROVIDING THE FLUID WITH A MORE UNIFORM VELOCITY DISTRIBUTION ACROSS THE WIDTH OF THE WIDENED STREAM AT THE OUTFLOW.

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