A papermaking machine including the combination of an endless moving screen having an upwardly-inclined run, a primary open headbox for supplying a moving stream of a primary liquid slurry into contact with the screen for forming a first sheet-like structure on the screen, the primary headbox including a pond regulator for cooperantly defining a discharge end for enhancing the discharge of the stream of liquid slurry into the upwardly-inclined run of the screen, a secondary closed headbox in a piggyback relation to and integrated with the pond regulator for supplying a moving stream of a secondary liquid slurry into contact with the screen and the advancing first sheet-like structure.

This invention relates to a two-stock delivery system for an inclined 
Fourdrinier type of papermaking machine. 
It teaches new and useful structural refinements in equipment for the 
formation of two-ply sheet-like structures envisioning apparatus 
incorporating an endless forming wire or screen of the Fourdrinier type 
and a cooperant stock delivery mechanism and an associated pond regulator 
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 slurry without permitting loss of 
the turbulence required to attain optimum dispersion thereof and a 
secondary stock delivery mechanism disposed in piggy-back relation to the 
primary delivery mechanism, 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. 
The web forming means in the form of the continuously-traveling 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 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 of their delivery thereto. 
The desideratum is to supply to each increment or subzone of the 
web-forming area 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 suction boxes located under the inclined section of the wire. 
In the conventional Fourdrinier machine, a certain volume of fiber 
suspension is discharged from a headbox through the slice 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. 
Webs of very different and special characteristics may be obtained by 
proper fiber selection. For example, thermoplastic fibers may be used to 
give heat sealing properties. Likewise, fibers with a high degree of 
shrinkage or a high degree of stretch may be employed. 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. 
Papermaking 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 fibers whether synthetic, regenerated or 
natural fibers, virgin or reclaimed. By textile fiber is meant a staple 
fiber having a minimum fiber length of one-half inch, such as can be run 
on a carding machine to form a sliver. 
The papermaking fibers used can be any of the natural fibers as used in the 
usual papermaking 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 papermaking practices, such as viscose, acetate rayon and the like. 
Structures formed herewith 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 cloth-like materials. 
The invention envisions means for continuously forming laminated webs or 
non-woven sheet-like structures made up of a pair of plies containing the 
same or different types and/or ratios of fibers or fibrids, which means 
comprehends a headbox inclusive of plural 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 flows 
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. 
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. 
The fibers of the 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. 
A pond regulator or stock-flow regulator is provided in association with a 
headbox as to define a pond chamber which converges relative to the wire 
and in the direction of movement of the wire to allow a 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. 
Pressure is controlled within an approach passage by way of allowed 
adjustments in the positioning of a 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 flow 
velocity in the forming area for any given gallonage or quantity of flow. 
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. 
Difficulties in web-forming techniques have been aggravated by increases in 
machine widths and speeds as the machinery of the art has developed. 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. 
Herewith, I provide means for supplying stock to each discharge or delivery 
orifice at desired pressures and velocities. 
According to the teaching hereof, adjustable pond regulator is adjustably 
positionable within the pond of a first stage headbox to provide means by 
which its lower or bottom wall coacts 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 stage headbox is positionable within the headbox, 
again to provide means by which 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 primary stage headbox, inclusive of the pond regulator, and the 
secondary stage headbox 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 reflective 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. 
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 short-length 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 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 one 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. 
Now with the sheets here envisioned, 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 wheretofore a web of uniform and 
homogeneous texture, free of clots, may be attained.

There is shown, fragmentarily and for illustrative purposes only, the wet 
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, 
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 base 10 on each of the tending 
and driving sides of the machine. 
A breast roll 12 is extendable across the machine width. 
A transversely-extending hinge roll 13 is disposed forwardly of the breast 
roll and will be movable vertically in an arc from the horizontal plane 
whereby the inclination of the reach of an endless forming wire 14 between 
the two rolls may be varied between a lower position of some 8.degree. 
from the horizontal and an upper position of some 35.degree. from the 
horizontal. 
Forming wire 14 is entrained around the breast and hinge rolls and is 
further movable forwardly to a couch roll (not shown) at the delivery end 
of the machine and is further supported by suitable idler and bottom wire 
rolls (not shown) for the return run of the wire, all as is conventional. 
An angle in the order of 15.degree. to 25.degree. is advantageously the 
optimum operating angle but same can be varied and a somewhat greater or 
smaller angle can be employed according to the characteristics required in 
the finished sheet. 
Forwardly of the breast roll and rearwardly of the hinge roll and beneath 
the inclined reach of the forming wire a compartmented suction box 16 is 
disposed, same constituting the main control unit for drainage and 
comprising, in essence, a plurality of suction boxes 16a, 16b, 16c, 16d, 
16e, and 16f arranged in echelon and maintained each under a variable 
degree of vacuum by individual suction supply means 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 not shown in detail. 
Supported upwardly of base 10 is a first stage or primary open-topped 
headbox 20 formed by transversely-spaced vertically-disposed side walls 22 
interconnected by a vertically-disposed rearward end wall (not shown) and 
a generally horizontal bottom wall 24 terminating in an apron 26 at its 
forwardmost extremity, slightly forwardly of the breast roll and in snug 
adjacency with the forming wire, all so as to define a pond therewithin 
cooperantly with the upper surface of the inclined reach of the forming 
wire. 
To prevent the slurry from draining rearwardly beneath the apron and over 
the breast roll, the usual seal arrangements (not shown) are provided. 
The slurry forming the pond is denoted by arrow 28. 
Disposed within the first stage headbox is a pond regulator, generally 
indicated by 40, same being constituted by transversely-spaced 
vertically-disposed side walls 42, interconnected by a generally 
vertically-disposed rearward end wall 44 extending therebetween and having 
unitary therewith and extending generally forwardly therefrom a bottom 
wall 46. 
Said walls cooperantly with the adjacent portion of the uppermost forming 
surface of the upwardly-inclined section of wire 14 define the bounding 
walls of a pond. 
Side walls 42 of the pond regulator will each be disposed snugly adjacent a 
respective side wall of the machine, one of which is shown as 50, so as to 
insure against stock leakage from within the first stage headbox save 
through a slice 54 defined by the forming wire and the forward terminus or 
lip of the pond regulator. 
The pond regulator functions to control the flow of stock thereunder, its 
bottom wall converging toward the floor of the pond and the forming wire 
being adjustable so that the bottom wall may be positioned relative to the 
wire in obtaining the desired and predetermined convergence as well as the 
desired dimensioning of the height of the slice. 
In piggy-back relation to the first stage headbox, a closed secondary 
headbox is mounted, same being generally indicated by numeral 60, and 
comprising the passage 62 having a perforated plate 64 connected therewith 
and therebelow for the discharge of a secondary slurry into the secondary 
approach passage 66 defined by the roof 68 of the forward portion of the 
pond regulator and having its own roof comprised of a rearward portion 70 
and a forward portion 72. The perforated plate 64 is arranged above and 
substantially perpendicular to the secondary approach passage 66, as can 
be seen in the FIGURE. 
Knuckles 74 and 76 at opposite ends of rearward portion 70 facilitate its 
adjustment in varying the degree of convergence of the rearward portion 
toward the wire. 
Knuckle 76 likewise facilitates the angularization of forward portion 72 as 
controlled by a jack mechanism 80 symbollically shown by the dot and dash 
line as connected to the forward terminus of forward portion 72. 
Control for the secondary passage is a delicate consideration owing to the 
fact that headbox feed is from above and at low machine speeds might act 
as a dropleg and tend to set up objectionable currents. For that condition 
the control is achieved by the use of a vacuum additionally applied to the 
top of the header so as, in effect, to offer a control of the flow from 
such header to the headbox which it supplies and enabling an accurate 
measurement of the fluent material being fed therewith to the machine. 
The vacuum chamber 90 is disposed directly above the secondary chamber. 
Principally, it serves to control the level of stock in the secondary 
headbox whereby cascading or entrainment of air is precluded. 
For higher machine speeds requiring higher hydrostatic heads, the vacuum 
chamber 90 will not be required. 
Indeed, this secondary nozzletype of headbox may be operated under pressure 
resulting in higher throughput or higher production capacity of the second 
ply. 
The suction box system previously referred to serves as the main control 
unit for drainage and 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. The regulating of the suction, as well as speed of the 
machine and position of the pond regulator, can be such as entirely to 
avoid orientation of the fibers or to create some orientation, if such is 
desired. 
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. 
The second stage headbox which fulfills the function of serving the second 
stage delivery of a slurry from the second pond onto the wire coacts with 
the 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 upper 
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. 
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, flow velocity is controlled with the primary approach 
passageway by way of adjusting the positioning of the 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. 
Two systems of control will be 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. 
In operation, stock is supplied from the pond of the primary headbox to the 
web-forming region or zone of limited extent defined by that portion of 
the wire adjacent the discharge orifice of the 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 sufficient to produce proper fiber distribution in the 
layer, with sufficient 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. 
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 two separate approaches 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. 
Because of the myriad combinations of fibers which may be desired, the two 
compartment arrangement will allow the operator considerable flexibility 
in achieving same. 
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 filing 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 the present invention that a very thin initial web 
will suffice to form the final composite web having good strength 
characteristics. 
The transverse inclined portion or section of the wire 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 moves 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. 
The advantages of the system here described are several. 
The primary headbox design envisions the use of highly-diluted slurries, as 
for example one made up of synthetic fibers requiring low consistencies, 
and relatively long forming lengths. 
The forming length can be adjusted so as to permit the formation of 
different fibers and fiber mixes dictating different drainage velocities. 
By selectively positioning the pond regulator 40 along the travelling wire, 
the forming length F1 can be changed to meet the drainage requirements. 
Similarly, the forming length F2 can be changed by selectively inserting a 
longer or a shorter roof 72 of the secondary flow chamber. 
The primary lip can be adjustable reference its distance from the forming 
wire so as to allow total control over the stock flow velocity and 
accordingly control over the MD:CD ratio. 
The piggyback design comprehends the formation of the top sheet or ply 
immediately following the formation of the base sheet, with a degree of 
fiber intermingling (base ply or sheet and top ply or sheet), resulting in 
exceptionally good ply bond. 
This degree of fiber intermingling is selective by virtue of the capability 
of positioning of the primary lip relative to the forming wire. 
Further, the secondary headbox is vacuum operated by means of a cooperant 
air chamber communicating with the secondary header, allowing the control 
of the speed of application of the top sheet to the base sheet. 
The piggyback arrangement offers the further advantage that the secondary 
headbox will deposit the top sheet irrespective of the location of the 
pond regulator. 
The top sheet normally will be of the lightweight type but it may be formed 
of slurries of higher consistencies wherewith lower flows may be required. 
A further advantage of the extended slice is that pressure formations are 
developed, all so as to permit higher production rates. 
The arrangement offers another distinct advantage in that the secondary 
headbox can be retrofitted, meaning that the pond regulator is of such 
configuration that at a subsequent time the secondary headbox can be 
adapted as an add-on.