US 3384537 A
Description (OCR text may contain errors)
May 21, 1968 v M. B. KELLER 3,334,537
MULTI-LAYER PAPERMAKING APPARATUS Filed April 27, 1965 2 Sheets-Sheet 1 INVENTOR.
MARTIN B. KELLER ATTO/WEX May 21, 1968 M. B. KELLER MULTI-LAYER PAPERMAKING APPARATUS 2 Sheets-Sheet 2 Filed April 27, 1965 MARTIN B. KELLER Ear/Ari ATTORNE).
United States Patent 3,384,537 MULTl-LAYER PAPERMAKING APPARATUS Martin B. Keller, Hudson Falls, N.Y., assignor to Sandy Hill Corporation, Hudson Falls, N.Y., a corporation Filed Apr. 27, 1965, Ser. No. 451,225 2 Claims. (Cl. 162-299) ABSTRACT OF THE DISCLOSURE A paper making machine including the combination of an endless moving screen having an upwardly-inclined run, a headbox, individual means for supplying a plurality of moving streams of liquid slurries to the headbox for conveyance into contact with the screen for forming a multi-ply sheet-like structure .on the screen, the headbox including pond regulators for cooperantly defining sections of a multi-section headbox with each of the sections having a discharge end for discharging the stream of a liquid slurry into the upwardly-inclined run of the screen, and means for adjusting the position of each pond regulator with respect to the headbox and other pond regulator and screen.
This invention relates to new and useful structural re finements in equipment for the formation of multi-ply sheet-like structures envisioning apparatus incorporating an endless forming wire or screen of the Fourdrinier type and a cooperant stock delivery mechanism or headbox or flow box compartmentalized to define a plurality of novel spreader sections, each capable of accommodating a large volume of a free-draining aqueous suspension of fibers known as a slurry or pond and designed to allow regulation of the linear velocity of its respective slurry without permitting loss of the turbulence required to attain optimum dispersion thereof, all so as to achieve herewith the laying down of a plurality of layers of stock in seriatim upon an upwardly-traveling inclined section of the forwardly-moving run of the Wire.
In broad aspect, the Web forming means in the form of the continuously-travelling forming wire travels upwardly at an angle during its passage through a part of the web forming zone of the machine, the suspensions of fibers dispersed in water vehicles being delivered independently of each other at spaced points along the inclined section of the wire and with predetermined velocities through discharge orifices or slices of the separate stages for deposit upon the wire, through which wire, by means of capillary action and surface tension, the water is drained so as to leave upon the upper planar surface thereof mats or webs of fibers, one superposed upon the other according to the order, timewise, of their delivery thereto. The desideratum is to supply to each increment or subzone .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, moving in the machine direction under such pressure as allows a delivery velocity substantially equal to the wire speed, with the water being drained through the wire either freely or by accelerated draining as induced by provided suction boxes located under the inclined section of the wire.
More particularly, herewith is allowed the variance of the velocities of the slurries in the plurality of distribution means incorporated within the headbox without loss of their desired degrees of turbulence, so as to provide static pressures of exceptional magnitudes upon the wire.
In a more specific aspect, the invention envisions means for continuously forming laminated webs or non-woven sheet-like structures made up of a plurality of plies containing the same or different types and/ or ratios of fibers 3,384,537 Patented May 21, 1968 or fibrids, which means comprehends a headbox inclusive of a plurality of distributing devices in stepped relation as to each other, and nested within the headbox in manner to contain separate slurries above the web forming surface of the inclined section of the wire and cooperant instrumentalities for controlling fiows .of these separate slurries to, and the in seriatim deposition upon, the wire in layers of desired thicknesses, all while the wire is continually motivated linearly beneath and relative to the slurries, thereby achieving the exertion of static pressures upon the wire.
As one refinement of the invention, the components coact so as to allow the introduction to the wire of slurries which may be of different but homogeneous characteristics as respects their quantative and/or qualitative formulations, and to impart to each said slurry the proper degree of velocity.
As a further refinement, flexibility is offered in the respect that the degree of angularity of the inclined section of the forming wire may be varied and the headboxes may be concomitantly adjustably positioned angularly relative to said inclined section.
Herewith, it is possible to produce a web or non-woven sheet-like structure of diversified fiber content and having superior physical characteristics, same formed through one aqueous dispersion of fibers delivered at one stage, which dispersion may be of one type, into a base layer or ply and, while such base layer or ply newly-formed upon the wire remains in a sufficiently fluid condition, depositing thereupon, through the means of a second stage headbox, another dispersion of fibers, which may be of the same or different type, in manner such that the fibers of the secondary layer .or ply are securely and uniformly bonded to those fibers of the base layer or ply so as to form a coherent web. And if desired, while such coherent web is newly-formed upon the wire and remains in a sufiiciently fluid condition, there may be deposited thereonto, by means of a third stage headbox, another uniform dispersion of fibers, which may be of a type the same as or different from the types used in the cases of the base and/or secondary layers, and again in manner such that the fibers of the last named layer are securely and uniformly bonded to the fibers of the earlier-produced coherent web, all with the singular advantage that complete fiber intermingling is attainable, free of the Web-splitting tendency commonly experienced on like machine'operations heretofore known.
conceivably, such formed structures may contain fibers of papermaking length and of textile length, so as to be considerably stronger and more uniform than non-woven fabrics heretofore formed, while possessing high degrees of softness, absorbency, flexibility and porosity, and offering other characteristics normally associated with clothlike materials.
Herewith may be produced either thin or heavy webs, as desired, containing fibers of widely diversified characteristics wherefore the allowed products have wide uses as substitutes for paper and/ or cloth.
The invention hereof permits the achievement of improved control of the velocities of the stocks in the web forming zone. For optimum web forming operation, it is a notorious fact that stock must flow through its discharge orifice and onto the forming area at a requisite velocity, results normally attained by the maintenance of a high head of stock in the pond, the velocity of stock at a slice being determined by the total pressure head of the stock as produced by the pressure .on the stock above that slice. With this invention, pressure is controlled within an approach passage by way of allowed adjustments in the positioning of the pond regulator in close proximity to or distantly from the wire. The closer the pond regulator to the forming surface, the narrower the discharge, and accordingly, the greater the pressure applied in the forming area for any given gallonage or quantity of flow. Such greater pressure induces a greater degree of drainage in the available forming area so that not only may more dilute stocks be used but also heavier webs may be produced. Too, the production of a web having improved profile is made possible, due to the fact that the web is formed from a pond, with the formation being controllable by the drainage rate on the wire rather than by a control of the fiber concentration in the slurry.
The admitted difficulties in web forming techniques, imposing in and by themselves, have been accentuated and aggravated by increases in machine widths and speeds as the machinery of the art has developed in its forward progress. As machine speeds have increased, higher flow velocities have been necessitated and the headbox component has been a limiting factor. To obtain a gravity head of stock capable of producing a continuous pulp supply at a proper pressure and delivery velocity, headbox constructions of objectionably excessive dimensions in order to maintain heads of great depths have appeared only to present concomitant problems, particularly in the case of machines operating over wide ranges of speeds. A high pond of stock offers the disadvantage of permitting stagnant areas within the pond, wherefore lumping ensues, and during lower speed operations, objectionable turbulence is encountered with the fall of the fiuid to the head or level required to produce the discharge velocity for the lower operating speeds, which turbulence has a detrimental effect on sheet formation. Herewith, I provide means for supplying stock to each of the discharge or delivery orifices at desired pressures and velocities, and without the aforesaid objectionable type of elevated construction.
'Pulp fibers fiocculate or settle unless agitated or kept in motion or caused by some physical-chemical means to oppose each other, flocculation causing a mottled or blotchy formation, and settling causing a massing of fibers, with the masses breaking away to create web spots and possibly web breaks. Hence, the consistent difficulties in the delivering of a uniform suspension to the web-forming region, aggravated by the problems inherent in avoiding current formation in the suspension, as optimum web formation depends upon two factors: (1) a uniform flow of the fluent mixture to the web-forming surface; and (2) a uniform dispersion of the fibers within the carrying medium.
According to the teaching hereof, a second stage headbox, serving as an adjustable pond regulator, is adjustably positionable within the pond of a first stage headbox to provide means by which its lower or bottom wall coaets with the lower or bottom wall of the first stage headbox and defines an adjustable slice or approach passage wherewith it is possible to attain minute changes in the dimensions of the first stage approach passage and hence changes in the velocity of the first stage stock immediately prior to and during formation on the wire. A third stage headbox, likewise serving as an adjustable pond regulator, is adjustably positionable within the pond of the second stage headbox, again to provide means by which its lower or bottom wall coaets with the lower or bottom wall of the second stage headbox and defines another adjustable slice or approach passage, again to allow the attainment of minute changes in the dimensions of the second stage approach passage and hence changes in the velocity of the second stage stock immediately prior to and during formation. The third stage headbox is additionally provided with an adjustable slice or approach passage wherewith it is possible to attain minute changes in the dimensions of the third stage approach passage and hence changes in the velocity of the third stage stock immediately prior to and during formation.
The primary stage headbox, the secondary stage headbox or pond regulator, and the tertiary stage headbox or pond regulator, are each adjustable with respect to each other and with respect to the wire which they serve whereby each may be adjustably related to the forming wire in any of a myriad number of positions of angularity, all in manner to give each approach passage a predetermined configuration refiective in the direction and speed of the charge of stock onto the wire in dependence upon the characteristics of the stock employed, the web to be formed therefrom, and the speed of operation.
The design hereof provides essential requirements of a headbox for the manufacture of webs such as here contemplated by offering:
(a) an ability to deliver a uniform quantity of solids to the wire across its full width,
(b) an ability to drain off the unusually large quantities of water needed for any particular basis weight,
(c) provisions for maintaining high turbulence in the approach section to maintain proper dispersion,
(d) provision for adjusting the flow just ahead of the forming zone to control sheet formation, and
(e) freedom from obstacles in the fiow passageways on which fibers can collect.
With the advent of synthetic fibrids adaptable for use in the art of forming sheet-like structures, as distinguished from the common wood pulps, it has been determined that the dispersion problem now dictates techniques different from those normally used in order to insure optimum operating performance at the forming area and to provide for the desired balance of physical properties in the final product, synthetic fibers being normally supplied as shortlength papermakers staple, being readily dispersible in water, and being characterized by cut length and by denier (fiber weight per unit length) with a given denier having a maximum length at which it is possible to obtain a best dispersion.
In conventional papermaking processes, the techniques have required the use of an aqueous dispersion of the fibers, wherefor water dispersible fibers of relatively short length, ranging from practically negligible lengths up to lengths of the order of three-eighths inch have been used. In most cases, the fibers have been natural fibers which usually are hydrated and have the property of bonding together to form a strong web, the formed paper products being usually relatively dense and stiff and lacking the porosity and textile appearance of non-woven fabrics.
In the manufacture of the sheet-like structures contemplated herewith, webs may be made from fibers of textile length or fibers of papermaking length or combinations of the two. Long non-hydrated fibers may be suspended in an extremely large proportion of water, and the resultant dilute suspension may be fed from one of the headboxes onto the wire, the water flowing freely and rapidly through the wire with an avoidance of eddy currents and through the fibrous web deposited on the wire, the fibers being deposited evenly on the wire without any rolling or rippling effects wherefore a web of uniform and homogeneous texture, free of clots, may be attained.
Dilute suspensions such as here envisioned may contain about one pound of fiber to twenty-five tons of water, that is, may have a consistency expressed as .02%. Higher consistencies such as .012% may be used, but in any case it will be recognized by those skilled in the art that even in this case the suspension is characterized as dilute to distinguish it from ordinary papermaking suspensions where the consistencies are of an entirely different order. Such dilute dispersions require a wet end capable of handling a large volume of an extremely freedraining slurry, and the use of the inclined section of the wire best responds to such dictates.
The compartmentalization of the headbox, according to the invention, accomplishes the subdividing into a plurality of headboxes, each provided with its own independent pulp feeding or delivering means whereby the respective suspension of fibrous material may be delivered under a certain pressure and velocity to the wire passing along a dividing plane between the discharge orifices disposed in stepped relationship along and adjacent the upper surface of the wire and the drainage chambers disposed along and adjacent the lower surface of the wire.
Since the arrangement of the wire permits the same to be made of any desired length, provision can be made for an exceptionally long zone of sheet formation, which greatly increases the performance of the machine. On the other hand, as contrasted with the radically greater length of wire in modern Fourdrinier machines, the wires hereof may be relatively short.
Another advantage of the machine according to my invention over known machines resides in the fact that the wire travels in a straight line for a considerable length of time after leaving the zone of sheet formation, whereby it becomes possible to make structures of considerable thickness. Furthermore, the wire may be made to continue in a straight travel, and the sheet may be left on the wire until the material has dried snfiiciently to permit is being lifted from the wire in a desired condition.
Yet another advantage lies in the fact that the wire may be driven at relatively high speed, with no danger of the outer layers of the sheet slipping off the wire being eliminated.
As still another advantage, a change in the length of the sheet forming zone may also be attained by altering the angle of inclination of the upwardly slanted section of the wire. A decrease of the inclination of the wire also counteracts the drawback that part of the deposited fibers would otherwise be washed off the wire where the latter emerges from the pulp.
According to yet another advantageous feature of my invention, the headbox is pivotally mounted at its lower end so as to be swung toward or away from the inclined wire. It is thus possible to reduce or increase the cross section of the upper headbox continuously in the direction of travel of the ascending part of the wire so as to adapt the cross section and together therewith the admitted quantity of pulp over the whole length of the wire in contact with the liquid in accordance with the properties of the suspended fibrous material.
These and other objects and advantages herein characterize the present invention, and distinguish it from previously known devices of a kindred nature.
The physical embodiment here described will be indicative of but one of the multiplicity of ways in and purposes for which the principles of the invention may be employed.
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 view, in side elevation, of an exemplary machine which may be utilized to carry out the invention: and
FIG. 2 is a sectional view, in side elevation, showing the machine with the wire and headboxes inclined at a different angle.
In the accompanying drawings, there is shown, more or less fragmentarily and for illustrative purposes only, the wet or breast roll end of an improved machine on which the step of forming a web may be advantageously carried out. The machine has certain elements and instrumentalities which are of old and well-known constructions and which, therefore, are not shown in detail and need not be explicitly described.
It will first be understood that the machine is preferably supported upwardly of a floor or base by means of a side frame A on each of the tending and driving sides of the machine, each said side frame being mounted adjacent its opposite ends upon pedestals (not shown).
At the upper side of the rearward end of each side rail A suitable bearings may be provided for journalling a breast roll B extending transversely therebetween, which breast roll will remain in a fixed position under all conditions of angularity or inclination.
Journalled on the respective breast roll bearing and extendable forwardly therefrom on each side of the machine is a table rail C and suitably journalled therein at the forward end thereof so as to extend transversely between the pair thereof is a hinge roll D, which hinge roll will be observed to be vertically movable in an arc of generally 15 from the horizontal plane projected through the center of breast roll B by means of a table rail adjustment rig E which is pivotally mounted at one lower end upon a stud F and is slidably engaged at its opposite upper end in a slot in a bracket G fixed to and depending from table rail C.
Thereby, a variation of the inclination of the wire, to be identified, between a 'lower position of some 10 from the horizontal and an upper position of some 25 from the horizontal is attainable.
An endless forming wire H, preferably of a relatively coarse mesh, is entrained around breast roll B and hinge roll D and around a strategical-ly-positioned couch roll (not shown) at the delivery end of the machine, with the upper or working run of the wire moving in the direction of arrows a and being supported by ,conventional table rolls (not shown) supported by and extending transversely between the spaced side rails between the breast and hinge rolls and between the hinge and couch rolls, and with the return run of the wire being guided by suitable idler or bottom wire rolls (not shown), all as is known.
Breast roll B defines the rearward terminus of the upwardly-inclined section of the upper working run of wire H and hinge roll D defines the forward terminus thereof.
Forwardly of hinge roll D, a longer downwardlyinclined section of the upper or working run of the wire extends to the delivery end of the machine.
The elevating of table rails C is controlled by the operation of the respective table rail adjustment rigs E which operate unisonly to adjust the table rails to the desired degree of inclination relative to the horizontal and hence to position the inclined section of wire H to the desired angle at which it will travel between the ponds of diluted fiber (to be described) disposed thereabove and the suction box (also to be described) disposed therebelow.
An angle in the order of 15 is advantageously the optimum operating angle but same can be varied and a somewhat greater or smaller angle can be employed according to the texture required in the finished sheet.
Immediately forwardly of breast roll B and rearwardly of hinge roll D and between table rails C and beneath the inclined section of wire H is a compartmented suction box K constituting the main control unit for drainage and comprising, in essence, a plurality of suction boxes K1 arranged in echelon and maintained each under a variable degree of vacuum by individual suction supply means K2 wherefore the greater part of the water on the wire may be sucked therethrough. Control of drainage therethrough will be accomplished by variations in the amount of vacuum in each as regulated by the conventional valved controls.
These suction boxes may be of any suitable number, and, as they may be of any well known construction, they are shown only diagrammatically.
Immediately therebelow may be positioned a save-all pan L into which any free water draining from the wire outside of the suction box area may be dropped, wherefrom it is discharged at the driving side of the machine for purposes of reuse.
A forming board M rearwardly of suction box K serves to support wire H in a straight line between breast roll B and suction box K and is suitably supported on an adjustable frame to allow vertical movement for its wire supporting function and horizontal movement for its positioning as close as possible to the breast roll.
A strategically-positioned stretch roll (not shown) will be adjustably movable for the purpose of tensioning wire H according to the varying of the inclination of table rails C and the positioning of hinge roll D.
To allow for wire changes, the machine will be supportable on cantilever beams extending between opposite sides of the machine wherefor the supporting frames on the tending side may be removed preparatory to wire removed.
Also supported upwardly of the floor or base and mounted so as to be pivotable relative to breast roll B and table rails C in a first stage headbox, generally indicated by 10, and constituted by transversely-spaced vertically-disposed side walls 12, interconnected by a vertically-disposed rearward end wall 14 and further interconnected by a vertically-disposed forward end wall 15 spaced forwardly of rearward end wall 14 and merging into a horizontally-disposed bottom wall or apron plate 18 unitary therewith and extending forwardly therefrom and having its forward extremity terminating approximately at the center line of the breast roll, all so as to define a pond therewithin cooperantly with the adjacent portion of the uppermost forming surface of the upwardly-inclined section of wire H.
A pair of overhead vertically-disposed horizontallyextending channel-shaped side frames or beams 22 are strategically disposed adjacent the outside of each side wall 12 and the first stage headbox is suitably secured thereto for support thereby.
At the opposite forward and rearward extremities of side frames 22, channel-shaped cross frames 24 interconnect said side frames, wherefor the provided rectangular frame may be movable unitarily.
At the rearward terminus of each side frame 22, a worm gear jack 26 is provided, each threadedly engaged in a jack stand 28 upstanding from and secured to the foundation or sole plates, and pivotally engaged at its upper extremity as by a pivot pin 30 pivotally engageable with a bracket 32 extending outwardly from the respective side frame.
A hand wheel 34, suitably keyed on each jack stand 28, allows the raising or lowering of the jack and concomitantly the raising or lowering of side frames 22 and of the first stage headbox therewith, all so as to assist in the support of the first stage headbox relative to the other machine components and more especially in the positioning thereof with respect to the path of movement of wire H on the side thereof where the wire surface is moving in general parallelism with the major portion of the lowermost axial plane of the headbox.
As the pitch of the Wire is adjusted, the first stage headbox may be adjusted to accommodate itself to such movement, same being pivotally mountedat upon a vertically-extending support post 42 projecting upwardly from the respective sole plate.
A plurality of inlet means 48 are provided transversely of the width of the first stage headbox for delivering to said headbox between rearward and forward end walls 14 and 16 respectively the first of a plurality of slurries of fibers and connecting to a flexible manifold for delivering slurry from a source of supply (not shown) to the first stage headbox compartment. The flexibility of the manifold is dictated by the'fact that the first stage headbox to which inlets 48 are fixed is movable.
Disposed within first stage headbox 10 is a secondary stage headbox or pond regulator, generally indicated by 50, same being constituted by transversely-spaced vertically-disposed side walls 52, interconnected by a generally vertically-disposed rearward end wall 54 extending therebetween and having unitary therewith and extending generally forwardly therefrom a bottom wall 56. A false bottom wall 58 may be spaced upwardly of and connected to bottom wall 56.
Cooperantly, said walls cooperantly with the adjacent portion of the uppermost forming surface of the upwardly-inclined section of wire H define the bounding walls of a pond.
Each side wall 52 of second stage headbox is disposed snugly adjacent the respective side wall 12 of firststage headbox 10 so as to insure againstleakage of stock from within the first stage headbox to a point forwardly 8 of end wall 54 of headbox 50 save through the slice 60 defined by bottom wall 56 of the second stage headbox and bottom wall 18 of the first stage headbox.
At each side of second stage headbox 50, a rearwardlyfacing slotted bracket 62 is provided which is adapted to be engaged by a pond regulator pin 64 which is threadedly engaged in a guide 66 mounted upon the respective side frame or beam 22 and is motivated selectively forwardly or rearwardly by rotation of a hand wheel 68, all wherewith the desired positioning of the second stage headbox relative to the first stage headbox and relative to wire H can be achieved.
Also secured to bracket 62 and depending downwardly therefrom first stage baffie pins 70 are provided to which is secured a first stage 'bafiie 72.
The second stage headbox functions as a pond regulator in the sense that its bottom wall converges relative to the wire for the controlled flow of stock under the regulator and from the slice 60 of the first stage headbox, said headbox being adjustable up and down and fore and aft relative to the wire whereby its bottom wall may be adjustably positioned relative to the wire and to bottom wall 18 of the first stage headbox thereby to obtain the desired and predetermined convergence therebetween as well as the desired dimensioning of slice 60.
The variable positioning of the bottom wall of this regulator will depend upon the speed of the wire, characteristics of the stock, desired characteristics of the web to be formed, stock velocity desired, and other variables.
Also disposed within the first stage headbox is a third stage headbox, generally indicated by 80, same being constituted by tranversely-spaced vertically-disposed side walls 82, interconnected by vertically-disposed spaced forward and rearward end walls 84 and 86 respectively extending therebetween, rearward end wall 86 having a forwardly extending bottom wall 88 unitary therewith and extending forwardly therefrom. A false bottom wall 90 may be spaced upwardly of bottom wall 86. Cooperantly, said walls with the uppermost forming surface 0 the adjacent portion of the upwardly-inclined section 01 wire H form another pond.
Each side wall 82 is disposed snugly adjacent the respective side wall 12 of the first-stage headbox so as to insure against leakage of stock from within the second stage headbox to a point forwardly of the rearward end wall of the headbox save through the slice 92 defined by bottom wall 88 of the third stage headbox and bottom wall 56 of the second stage headbox.
The third stage headbox is provided with an adjustable slice 96 by means of an extension wall 98 pivoted at 100 to the lower end of wall 84 and extending angularly downwardly therefrom. The lower end of extension wall 98 may be adjusted upwardly or downwardly to vary the size of slice 96 by an adjustment means 102 depending downwardly from and threadedly engageable with a bracket 104 fixed to wall 84 and pivotally engaged with extension wall 98. A hand wheel 106 mounted upon a screw 108 allows the raising or lowering of extension wall 98.
At each side of third stage headbox 80, a forwardlyfacing slotted bracket 110 is provided which is adapted to be engaged by a pond regulator pin 112 which is threadedly engaged in a guide 114 mounted upon the respective side frame or beam 22 and is motivated selectively forwardly or rearwardly by rotation of a handwheel 116, all wherewith the desired positioning of the third stage headbox relative to the first stage headbox and relative to wire H can be achieved.
The area defined by that area within first stage headbox 10 and rearwardly of second stage headbox 50 is termed a first compartment for containing a first pond, the area defined by that area within second stage headbox 50 and rearwardly of third stage headbox 80 is termed a second compartment for containing a second pond, and the area defined by that area within third stage headbox 80 is termed a third compartment for containing a third pond, rearward end wall 54 of the second stage headbox serving as the forward end wall of the first pond, and rearward end wall 86 of the third stage headbox serv ing as the forward end wall of the second pond.
Stated in another way, the second and third stage headboxes are nestable within the first stage headbox and are adjustably positionable relative thereto, all so as to permit the operator to adjust the horizontal position of these boxes and hence the opening of each nozzle or slice.
Headbox 10 is disposed immediately above the upwardly inclined portion of travelling wire H entrained around breast roll B, same being in close running proximity to the forward end of bottom wall 18 of the first compartment, which forward end of bottom wall 18 is forwardly-facing and laterally-extending across the wire width in manner to constitute an apron related to the breast roll and wire and to define the lower wall of the restricted slice or approach passageway 60 leading from the first compartment, the upper wall thereof being defined by bottom wall 56 of second stage headbox 50 wherefrom stock is dischargable from the first compartment onto wire H.
To prevent the slurry from draining back underneath the apron and over the breast roll, the usual seal may be provided.
As stated, the lower wall of the secondary stage headbox serves as a pond regulator for the first stage headbox, and as the secondary stage headbox is adjusted vertically and fore and aft, relative thereto, its lower wall is positionable relative to the wire.
Slurry is introduced to the second compartment as by a secondary inlet header 130 supporting a plurality of header conduits 132 connected to a source of slurry sup ply (not shown) and disposed transversely relative to the machine across the headbox width and discharging via downwardly depending legs 134 into the second compartment.
Slurry is introduced to the third compartment as by a tertiary inlet header 146) supporting a plurality of header conduits 142 connected to a source of slurry supply (not shown), and disposed transversely relative to the machine across the headbox width and discharging via downwardly depending legs 144 into the third compartment.
Control for these conduits is a somewhat delicates consideration owing to the facts that headbox feed is from above and they might act as droplegs and tend to set up objectionable currents. Here control is achieved by the use of headers which are only partly filled, as for example, approximately one-half, with the fluid which it conducts, there being a vacuum additionally applied to the top of each header so as, in effect, to offer a control of the flow from such header to the respective headbox which it supplies and enabling an accurate measurement of the fluent material being fed therewith to the machine.
By means of the so-called vacuum drop legs, the level of the material in each compartment is controlled. Nor mally, the lower extremities of the drop legs will be submerged in the stock of the headbox which they serve so that cascading or entrainment of air is eliminated.
The entrainment of air in the pipes serves to create negative pressures so as to remove air from the top and to put down cascading in the pipes and to control the fluid fiow therethrough.
Preferentially, in order to accommodate to low flows in the second and third stage headboxes, as will sometimes be dictated by the type of sheet being formed, two headers will be provided for each such headbox with onehalf of the total number of vertical legs being connected to each so that when low gallonage flows are called for, only one of the headers for each headbox will be rendered operational, the other of the headers being rendered nonoperational as by suitable valving controls.
An upright baffle 150 may be disposed within each of the second and third compartments and extend transversely thereof, being fixed or pivoted to the opposite side walls thereof and serve to divert the stock either under or over the respective battle and to adjust the flow accordingly.
In the case of the first compartment, the stock will flow upwardly over baffle 72 or thereunder according to the locating of the baflie.
Suction box K serving as the main control unit for drainage is co-extensive with the various openings of the headboxes and the various compartments thereof are connected to suction pumps (not shown) having sufficient capacity to handle the volumes of fluid discharged onto the wire. The result is that the water is sucked through the wire and the newly-formed wet, but porous, highly dispersed and uniform but non-oriented fibers of the web. By providing ample suction at the suction box, substantially all of the water can be drawn downwardly through the web, thereby avoiding turbulence and water flow outwardly along the surface of the web which might cause disintegration or non-uniformity of the web, wherefor substantially all of the fibers are deposited and drawn into the web without escaping outwardly to atmosphere. The regulating of the suction, as well as speed of the machine and position of the pond regulators, can be such as entirely to avoid orientation of the fibers or to create some orientation, if such is desired.
The fibers thus deposited in and on the porous moving web, while it is still wet and fluid, will be interlocked or intermeshed with the web so as to form a strong bond with each other.
The second stage headbox which fulfills the function of serving the second stage delivery of a slurry from the second pond onto the wire additionally serves as an adjustable pond regulator for the first pond within the first stage compartment by virtue of the fact that its lower or bottom wall coacts with the lower or bottom wall of the first stage headbox wherewith it is possible to attain minute changes in the dimensions of the first stage approach passage immediately prior to and during stock formation on the wire.
The third stage headbox, likewise serving as an adjustable pond regulator, is similarly nested so as to provide means by which its lower or bottom wall coacts with the lower or bottom wall of the second stage headbox wherewith it is possible to attain minute changes in the dimensions of the second stage approach passage immediately prior to and during stock formation on the wire, the third stage headbox being provided with its own adjust-able slice means disposed to provide means cooperant with the lower or bottom wall of the third stage headbox whe rewith it is possible to attain minute changes in the dimensions of the third stage approach passage immediately prior to and during stock formation on the wire.
The pond regulators (the second and third stage headboxes) are now observed to be adjustable members disposed within the respective ponds (the second stage headbox being disposed within the pond of the first stage headbox and the third stage headbox being disposed within the pond of the first stage headbox) each being movable with respect to the walls within which it is nested and with respect to the adjacent wire so that it may be related to the wire in any of a myriad number of positions of angularity, in manner to control the direction and speed of stock onto the wire. That is, the lower wall of each pond regulator defines, cooperatively with the adjacent wire, an approach passage, according to a predetermined configuration in dependence upon the characteristics of the stock, the web to be formed, and the speed of operation, so that a reproducibility of results is easily possible.
Such construction permits an improved control of the velocity of the stock at the forming area, it being well known that, for optimum high speed operating stock must be allowed to flow through its discharge orifice and onto the forming area at a requisite velocity. By the pond regulating means hereof, pressure is controlled with each approach passageway by way of adjusting the positioning of. the respective pond regulator in close proximity to or distantly from the wire, it being appreciated that, the closer the pond regulator to the forming surface, the narrower the discharge, and accordingly, the higher the velocity, the greater the pressure that might be applied in the forming area. Such pressure permits a greater drainage in the available forming area, wherefore more dilute stocks may be used, and further, wherefore heavier webs may be made than would be possible without such pressure. Too, the production of a web having better profile is made possible, due to the fact that the web is formed from a pond, which formation is controllable by the drainage rate on the wire rather than by any control of the fiber concentration in the slurry.
Each headbox may, if desired, be provided with a suitable form of adjustable overflow means, to accurately gauge the pressure head within such box. Such means may comprise removable gates mounted one about the other, whereby opening of any one will cause the surplus pulp mixture to overflow at that point, the material overflowing being returned in any suitable manner to the supply source. The quantity of pulp mixture flowing through the overflows may be greater than the amount flowing onto the wire so that there will be such an overflow, thus maintaining the pressure head at a predetermined height, and
insuring uniform flow onto the wire.
Thus, two systems of control are observable-first a control by means of widening or restricting the respective slices, and second, a control by means of changing the volume of the respective heads.
As previously mentioned, the suction box may be made with a plurality of water extraction compartments which add to the flexibility of drainage control. The compartments, open to the inner face of the wire, may be varied in accordance with various factors, such as variations in the nature of the stock for better control of the thickness and formation of the sheet. Each such compartment preferentially, though not obligatorily, will include :air extraction and water extraction conduits for the separate withdrawal of air and water therefrom.
In operation, stock is supplied from the pond of a headbox to the web-forming region or zone of limited extent defined by that portion of the wire adjacent the discharge orifice of the respective headbox, as by forcing same through the approach passage and onto the wire forming surface as a layer or ply, the stock so applied containing the required amount of fiber in an amount of water sutficient to produce proper fiber distribution in the layer, with sutlicient water drainage being effected during the time period that the formed web remains on the wire to produce a coherent sheet capable of being couched therefrom.
In the conventional Fourdrinier machine, a certain volume of fiber suspension is discharged from a headbox through the slot between a slice and apron and is deposited upon the wire. The general desideratum of the suspension carrying the exact same concentration of fiber at every point transversely of the wire frequently fails wherefor heavy and light streaks across the sheet result. With the invention hereof, contrariwise, means is provided to control this unevenness before the stock exits from the pond, whereby a levelness of a degree heretofore unobtainable is achievable.
It will be understood that the slurries fed to the respective compartments may vary as to fiber content and the like to meet the requirements of the particular laminated product desired to be formed.
For example, the use of three separate compartments will enable an operator to pass through a first approach passage a slurry of fibers or fibrids for the face of the sheet to impart thereto softness and filmy appearance, to pass through a second approach passage longer and stronger synthetic fibers to give the sheet body, and to pass through a third approach passage either a third 12 type of fiber or again the type used in either the first or second compartments.
Because of the myriad combinations of fibers which may be desired, the three compartment arrangement will allow the operator considerable flexibility in achieving same.
The construction is based upon the principle of -a control of the drainage of the water of the papermaking stock through the forming wire within the forming area per se, under conditions of pressure exerted over or above the wire and within the forming area, Wherefore initial formation on the wire is controlled.
A pond regulator or stock regulator is so provid d in association with a headbox or pond chamber as to converge relative to the wire and in the direction of move ment of the wire and to allow control of the flow of stock under the regulator and over the forming area of the wire, the pond regulator being adjustable up and down and fore and aft such that the lower wall thereof may be adjustably positioned relative to the wire as to obtain the desired and predetermined slice dimension according to wire speed, stock characteristics, stock velocity, desired web characteristics, and other variables.
In known prior art devices, the stock is permitted to squirt and spatter onto the forming area. In contradistinction, by the apparatus hereof, the stock is captured, within the width of the forming area wherewith water may be' removed under controlled conditions.
Hereby a combined web made up of a plurality of plies may be continuously carried forwardly by the Wire to be subsequently couched from the wire and dried and, otherwise treated in accordance with conventional papermaking techniques. The resulting web products may have many of the characteristics of a paper product, insofar as strength, uniformity and the like are concerned, while at the same time, it may have many of the properties of a textile material, including softness and porosity.
The slurries in the stepped headboxes are put into confronting contact with the continuously moving wire. The Waters from the slurries drain through the Wire into the suction boxes and save-all from which it may be withdrawn through suitable piping for re-use. As the waters drain through the wire, the fibers of the respective slurries are deposited on the wire in a uniform manner to form a multiply web.
Preferentially, each slurry is of the type which Will form upon the wire a porous web having a free fiber structure characterized by an ability to lose water rapidly. As a result, the water normally filling the interstices of the web as it forms on the wire quickly drains through the wire leaving a web structure which is highly porous to air.
The thickness of the web formed will depend, of course, on the composition or dilution of each slurry and the rate at which the wire is travelling. It is an advantage of thepresent invention that a very thin initial web will suffice to form the final composite Web having good strength characteristics.
It is necessary that the pulp be fed under a pressure suflicient to overcome the hydrostatic pressure which depends on the liquid level in the headbox. The height of the liquid levels in both chambers may be adjusted on the one hand by a control valve arranged in the discharge conduit for the drainage Water and on the other hand by varying the feeding pressure of the pulp being fed into the upper chamber. By adjusting the liquid level in both chambers to a desired ratio in the length of the zone of sheet formation may be determined and adapted to a great extent to the properties of the material.
The transverse inclined portion or section of wire H forms, in effect, a perforated inclined and movable wall of a box or pond in which, are maintained predetermined levels of the highly-diluted stocks so that, as the wire move-s upwardly, the stocks from the boxes flow rapidly onto the wire, the fibers being deposited upon the wire in an even and uniform manner without rolling or rippling and the water passing therethrough. operationally, the fibers are suspended in extremely large proportions of water, and these dilute suspensions are made to flow freely and rapidly through the inclined section of the wire leaving the fibers deposited on the wire, the water flowing freely and rapidly without eddy currents through the wire and through the Web of fibers deposited thereupon, the fibers being deposited evenly on the wire as a web without any rolling or rippling effects, whereby a web of any desired length and of uniform and homogenous texture throughout and free of clots may be achieved.
Such results have not been entirely possible with Fourdrinier machines as heretofore known, as it has been and is the usual practice to arrange the wire horizontally or to decline it at a desired angle from the breast roll end. With such an arrangement, where the stock is greatly diluted, a rolling effect is produced, it being observed that the stock is flowed onto the wire in the direction of the movement of the wire. It is also of importance to note that, if the fibers were hydrated, the character of the web formed upon the wire is such as not appreciably to retard the free and rapid flow of the water through the wire and the web as the latter is being formed thereon.
Conceivably, paper'making and textile fibers can be formed by the means hereof 'into a combined web or papermaking or textile fibers may be used alone.
The textile fibers used can be any fiibers whether synthetic, regenerated or natural fibers, virgin or reclaimed. By textile fiber is meant a staple fiber having a fiber length of from one-half inch to four inches, such as can be run on a carding machine to form a sliver. Among the synthetic fibers which may be utilized are cellulose esters of acetate and viscose rayon; methyl, ethyl and benzol cellulose; vinyl compounds such as vinyl chlorides; vinyl acetates and the copolymers of the same; polymers f the styrenes; polyam'ides such as nylon; and the .proteinaceous fibers such as those formed from casein and soybean. Among the natural fibers which may be used are long staple natural fibers such as cotton, flax, jute, hemp and r-amine.
The 'papermaking fibers used can be any of the natural fibers as used in the usual pape-rmaking processes, such as wood, jute, cotton and sisal, either in their full fiber length or refined and hydrated to shorter lengths to give increased strength. They can also be of longer length and may include synthetic fibers in which longer fiber lengths are used as compared to usual papermak-ing practices, such as viscose, acetate rayon and the like.
While the selection of a particular furnish is subject to wide variation within the skill of one versed in the art, it has been found that in the event that the textile fibers to be added to the web are composed of synthetic or regenerated fibers having little binding power, of themselves, it is preferred to select fibers for use in the slurries which will have a high binding strength or to add a chemical binder to the slurries in the form of starch, urea formaldehyde resin, polyvinyl acetate, polyvinyl chloride, resin, rubber latex, glue, sodium carboxymethylcellulose, or the like.
As will be realized, webs of very difi'erent and special characteristics may be obtained by proper fiber selection. For example, thermoplastic fibers may be used to give heat scaling properties, or fibers with a high degree of shrinkage or a high degree of stretch may be em- .ployed. For other purposes, the fibers may consist of some which are soluble in certain solvents and insoluble in others.
Owing to the allowability of a very wet paper web with a textile web, it is possible to obtain practically unlimited combinations. For example, it may be desired to form a final web having entirely opposite characteristics on its two sides as where one side may be composed of very short, highly hydrated fibers forming a thin filmlike paper web, while the other side may be composed of long, soft textile-length fibers entirely dissimilar in physical characteristics. Or one side may be made highly impervious to liquids while the other side may be made highly absorbent.
Grain ratio, porosity, flexibility and strength may be controlled to a degree not possible heretofore. The webs and the components of the webs may be made as thick or thin as desired within a practical range. In general, the maximum thickness which can be obtained in the final Web will be about one-eighth inch. The usual range of openation generally will be to form a final web product having a thickness of .001 to .030.
1. In a papermaking machine, the combination of: an endless Fourdrinier wire having an upwardly-inclined run, a multisection headbox including vertical side walls and a vertical rear wall and pond regulators arranged within the headbox and spaced as to each other and as to the rear wall for cooperantly defining headbox compartments with each compartment being arranged for receiving through an inlet and for discharging through an outlet a stream of liquid slurry, the outlets of the headbox being spaced from and in stepped relationship as to each other, the wire being disposed below the headbox and the upwardly-inclined run of the wire being disposed in confronting relationship with the plurality of outlets of the headbox and emerging upwardly from the uppermost of the outlets for aiding in the forming of a multi-ply web upon the wire, and means for adjusting the position of each pond regulator with respect to the headbox and other pond regulator and wire.
2. Apparatus for the formation of a multi-ply sheetlike structure comprising: an endless foraminous forming wire having a variable upwardly-inclined run during its passage through a part of the web forming zone of the apparatus, a multisection head-box, means for supplying a plurality of streams of liquid slurries to the headbox, the headbox including a vertical wall and a horizontal apron and pond regulators for cooperantly defining the sections of the multisection headbox with each of the sections having a discharge orifice for discharging in seriatim a liquid fiber slurry onto the upwardly-inclined run of the wire, means for supplying a different liquid fiber slurry to each section of the headbox, means for adjustably relating the positions of each pond regulator in any number of positions of angularity with respect to the headbox and the other pond regulator and the wire for the regulation of the respective discharge outlet, suction compartment beneath the inclined run of the wire for assisting in the formation of a multi-ply web upon the wire by the withdrawal of the fluent medium from the pulp stock, and means for supplying a suction to each of the suction compartments.
References Cited UNITED STATES PATENTS 1,532,083 3/1925 Shaw 162299 X 1,754,370 4/1930 Raynes 162-298 2,259,859 10/1941 Covey 162299 X 2,881,072 4/1959 Clark 16220*1 X 2,890,149 6/1959 Muller 162-350 X 3,190,790 6/1965 Ploetz et al. 162299 X S. LEON BASHORE, Primary Examiner.