US3041235A - Papermaking machine - Google Patents

Description

June 26, 1962 c. A. LEE 3,041,235

PAPERMAKING MACHINE Filed Feb. 12, 1958 2 Sheets-Sheet l INVENTOR.

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June 26, 1962 c. A. LEE

PAPERMAKING MACHINE 2 Sheets-Sheet 2 Filed Feb. 12, 1958 INVENTOR. fi/za rZea QZZarzZcZ, BY @054, Mfiwuw United States Patent Ofifice 3,041,235 Patented June 26, 1962 3,041,235 PAPERMAKING MACIWE Charles Allen Lee, Neenah, Wis, assignor, by mesne assignments, to Huyek Corporation, a corporation of New York Filed Feb. 12, 1958, Ser. No. 714,861 Claims. (Cl. 162-410) This invention relates to papermaking. In particular, it relates to certain improved papermaking procedures and to certain novel papermaking machinery made possible by the utilization of those procedures.

In the manufacture of paper by conventional practices an aqueous suspension of papermaking fibers, with or without additional papermaking materials, is delivered to la foraminous forming fabric or carrier; in the usual Fourdrinier machine this forming carrier constitutes a continuous, woven fabric Ibelt. In order to accomplish good formation in the paper web, the suspension of fibers is quite dilute, rarely containing in excess of a few percent of fiber and usually containing less than 1 percent.

As a result, the web which is formed on the forming carrier in the initial stages of the papermaking operation is exceedingly fragile in nature. Because of certain wellunderstood limitations inherent in papermaking equipment and in cellulose fibers, it has heretofore been necessary to remove this web from the carrier at a solids content of less than about percent.

The present invention is predicated on the discovery that important improvements can be accomplished by passing the fragile wet web, while it is still in place on the forming carrier, through a resilient pressure nip having certain particular characteristics. More specifically, this procedure, which is a material divergence from accepted papermaking practices, accomplishes important improvement in the physical characteristics of the web. It also makes possible the delivery of the web by the forming carrier at solids contents which are substantially in excess of the solids contents obtainable in conventional equipment. This increase in the solids content of the web effects further improvement in the quality of the paper, such improvement resulting from certain changes in the physical properties of the web, and from the elimination of the deleterious effects now resulting from the need, in existing equipment, to transfer a low solids content, fragile web from the forming carrier to the subsequent elements of the papermaking machine.

The principal object of the invention is the improvement of papermaking procedures in accordance with the discovery outlined above. vention include: the provision of simple and eflioient apparatus for practicing the invention; the simplification of the construction of papermaking machinery generally, and particularly the simplifying of the web transfer and carrier mechanisms; and the provision of a paper-making procedure which not only results in a higher quality paper but also permits the use of less expensive fiber furnishes, or of special furnishes not capable of efficient processing on existing equipment.

These and other objects will be made apparent in the accompanying drawings and in the following description of certain preferred embodiments of the invention.

In the drawings:

FIGURE 1 is a diagrammatic illustration of a papermaking machine in accordance with the invention.

FIGURE 2 is a diagrammatic illustration of another papermaking machine embodying the invention.

FIGURE 3 is a diagrammatic illustration of another papermaking machine embodying the invention.

As pointed out above, papermaking machines now in commercial use embody a foraminous carrier constructed More specific objects of the inof wire or other material on which the paper sheet is initially formed as a very low solids content, fragile web. This web is removed from the forming carrier at a time when the solids content thereof is less than about 20 percent by weight. In the practice of the present invention, the web, while on the forming carrier, is subjected to the action of a resilient pressure nip having certain particular characteristics. As a result of its passage through this nip, a paper web possessing improved properties results. Further, the solids content of the web is increased to at least 25 percent, and can be increased to values of 35 percent or more, with important accompanying advantages.

The effect of passing the fragile wet web through a resilient nip in accordance with the invention, while not fully understood, appears to be a result of controlled elongation and/ or working under pressure while the web is supported on the carrier. The elongation and working or stretching effect can be understood by considering a conventional resilient pressure nip comprising two rolls, one having a rubber surface and the other having a hard surface, each having an overall diameter of D. The rolls, however, are held together by a sufficient force so that their axes are separated by a distance somewhat less than D, whereas if their surfaces were in lightly touching relationship, the axes would be separated by a distance of D. The rubber surface, consequently, is deformed by the other roll as the two rolls are forced together. Instead of the two rolls being in a touching relationship at a point, or actually a line along the nip, the rubber surface is so deformed that it is in firm contact with a substantial area of the other roll.

It should be pointed out that the rubber surface is anchored to the roll on which it is used. This means that only the rubber relatively near and within the area of contact between the two rolls will be deformed. The extent of deformation, of course, will depend upon the amount of force holding the two rolls together, the thickness of the rubber cover, and the elastic characteristics of the rubber. However, in any event, in using the present commercial rolls at conventional pressures the deformation will be substantially localized to the area of contact between the rolls.

Due to the localized nature of the deformation any surface increment of rubber outside the area of deformation will be in a substantially unstretched condition. As the increment approaches and finally enters the area of contact, due to the incompressive nature of rubber, it will be stretched or elongated with the elongation reaching a maximum when the increment is approximately bisected by a line between the axes between the two rolls. As the increment moves past this line, the elongation will decrease until the increment finally leaves the area of deformation at which time it will return to its normal repose condition. Similarly, the unit pressure or force exerted between the surface of the rubber increment and the other roll surface will rise from zero, at the point of initial contact between the two surfaces, to a maximum or peak pressure at approximately the point of maximum elongation, returning gradually to zero as the rubber increment leaves the area of deformation.

For purposes of terminology the term resilient nip refers to a pressure nip having at least one deformable surface of a resilient noncompressible material.

Elastomers such as natural or synthetic rubbers are typical examples of such resilient noncompressible materials. The presence of holes drilled into such materials will somewhat affect the degree of deformation in a pressure nip but does not alter the fact that they perform as noncompressible resilient materials.

A resilient nip thus would be distinguished from a felt nip where at least one of the rolls has a felt jacket or the like. Felt, while it is deformable and may even be resilient to some extent, is not noncompressible. This compressibility of felt is at least partially due to the numerous interstices within and between the fibers or yarns comprising most fabrics such as felt. Consequently, the elongation and contraction present with rubber and similar resilient noncompressible materials is not present with felt.

It should be further pointed out that a pair of hard rolls, due to their nondeformable characteristics will not provide the aforementioned elongation and contraction.

Various felt and web combinations may be present in such nips, but this does not materially alter the elongating and contracting effect of a resilient nip, nor does it provide this effect in the nip of a pair of hard rolls.

As an increment of carrier proceeds through a resilient nip it will first be elongated and then be de-elongated or contracted similarly to the elongation and contraction of the corresponding increment of the resilient roll surface. Where a pair of resilient surfaced rolls is used, the elongation and contraction will affect the acrrier and any other materials present in the resilient nip. Where only one of the rolls is resiliently surfaced, the elongating and contracting effect of the resilient nip on the carrier will be most pronounced where the carrier is in direct contact with the resilient surface, due to the frictional contact under pressure between the carrier and the resilient surface. In order that the carrier may cooperate with a resilient nip in accordance with this invention, the carrier should be elastic in nature, at least to the extent of expanding and contracting without permanent set or damage during its passage through a resilient nip of the type defined.

As a result of this discovery, it is possible to integrate the forming section and pressing section of a papermaking machine, so that the Web may be formed and pressed on the foraminous carrier, as will be described in detail later on. In the practice of the invention, the wet fragile web, while on the carrier on which it was originally formed, is passed through a resilient nip of such construction that there will be produced at least a 0.5 percent elongation of the forming carrier. In addition, the superimposed web and carrier are subjected to a peak pressure of at least 100 pounds per square inch in passing through the resilient nip. Because of its intimate contact with the carrier, the web will be subjected to the same elongation and contraction as that of the carrier, as previously described. The peak pressure is not the average unit pressure within the nip but rather the maximum pressure to which the web and carrier are subjected in passing through a resilient nip. Since the industry generally speaks, in terms of pressure in pounds per lineal inch, measured parallel to the roll axes, the following formula is given for converting from pounds per lineal inch to peak pressure in pounds per square inch:

where a is equal to the nip width in inches; L is equal to the load in pounds per lineal inch; and q is equal to the peak pressure in pounds per square inch.

One material from which a carrier suitable for the practice of the invention has been constructed is nylon. Nylon is a well known polyamide synthetic fiber which has excellent strength and yet is elastic, and it can be woven or otherwise processed into a fabric which is suitable for use as a forming carrier. It will be apparent that other materials, particularly in the synthetic fiber field such as polyester fibers sold under such trademarks as Dacron, acrylic fibers sold under such trademarks as Orlon, and Dynel, and vinyl derivative fibers sold under such trademarks as Saran may be used in the construction of other suitable forming fabrics or carriers. The mesh or fineness of weave of the forming carrier will depend, as in present papermaking practice, on the particular type and weight of paper to be manufactured.

The present invention makes possible the use of forming carriers of finer mesh than has heretofore been considered practical. In the manufacture of certain types of paper, important advantages will result from the use of such finer mesh carriers. For example, in the manufacture of book paper or newsprint, a forming carrier having a mesh count greater than 70 x 70 (i.e. x 80 or higher) will produce improved quality paper for printing without loss of machine speed.

The terms forming carrier and forming fabric are used interchangeably herein to define foraminous carriers suitable for the formation of paper webs from fiber suspensions of the types ordinarily used in papermaking. This means that the material of which the carrier is made, as distinguished from such materials as felts and canvasses which are not used in web formation, must be capable of draining water from a web being formed thereon at quite a substantial rate. For comparative purposes, the top felt of a conventional papermaking machine will drain about 0.01 cubic foot of water per second per square foot under 10 inches water head. A typical forming carrier or fabric will drain over one hundred times as much water, a representative value being 1.84 cubic feet of water per second per square foot under 10 inches water head.

Referring to FIGURE 1, there is shown one example of a papermaking machine embodying the invention. The papermaking machine is provided with a headbox 10 adapted to discharge stock of suitable consistency containing fibers for making paper onto a continuous forming fabric 12 at a breast roll 11. The forming fabric 12 is supported to receive stock discharged from the headbox in a continuous stream and is normally driven at a selected uniform rate, as will be described later.

After the stock has been discharged onto the forming fabric, the latter permits suflicient liquid to drain so that a web 17 begins to form in the well known manner. As shown in the drawing, it may be desirable to support the forming fabric by one or more table rolls 16 or suction boxes (not shown) to facilitate draining and ultimately the formation of the web. At a suflicient distance away from the headbox for the web 17 to reach a plastic state, as distinguished from the liquid state of the stock, the forming fabric and the web pass through a resilient pressure nip 18.

Resilient pressure nip 18 is formed by rolls 19' and 20, roll 20 being provided with a resilient rubber cover 2%. The rubber cover and shell of roll 20 may be drilled with a plurality of holes to communicate with a stationary suction box 22. Under some circumstances, as where crushing of the web is experienced due to the presence of excess water, it may be desirable to contact the exposed face of web 17 with a belt 21, shown by broken lines. The belt 21 may be a second forming fabric or a conventional felt. It may also be desirable to provide roll 19 with a rubber cover (not shown).

The forming fabric 12 and the web 17 are subjected to elongation and pressure by the action of the resilient nip 18, and water is removed.

Most of the important advantages of the invention may be accomplished by the use of a single resilient pressure nip. For example, after leaving the resilient pressure nip 18, the web may be removed from the carrier and passed into any desired drying means. However, the use of several resilient pressure nips in series will be found advantageous for best efficiency, maximum water removal and ease of operation. Where a series of resilient pressure nips is used as illustrated in FIGURES 1, 2 and 3, it is desirable to construct and arrange them in order of increasing nip peak pressures, above the minimum peak pressure of 100 pounds per square inch. This minimizes any crushing tendencies and at the same time removes the maximum amount of water from the web. By this means the web solids contents may be increased to above 35 percent and, in some instances, to above 40 percent.

Referring again to FIGURE 1, carrier 12 and web 17 progress from the resilient pressure nip 18 into contact with a conventional Yankee drier 24. Such driers may be 12 feet in diameter and having a metallic surface. In making creped papers or machine glazed papers, the wet web is pressed firmly against the hot drier surface by a resilient covered roll. Desirably, additional water is removed at this point by pressure applied as illustrated by a pressure roll 23 having a resilient rubber cover 23a. The rubber cover and shell of roll 23 may be drilled with a plurality of holes to communicate with a stationary suction box 22. Roll 23 and drier 24 thus provide a second resilient pressure nip in which both carrier 12 and web 17 are subjected to pressure and elongation. If desired, the forming carrier may leave the web after this nip, returning to the breast roll along a path indicated by broken lines.

In some machines, an additional rubber covered pressure roll 25, which may have a vacuum box 22, is provided for increased water removal. In these machines the forming fabric 12 may follow the web along the drier contour, passing the web through this resilient nip and around roll 25, as shown in FIGURE 1, before returning to the breast roll over guide and stretch rolls 26. It is desirable to incorporate one or more conventional spreader type rolls 29 to prevent gathering and wrinkling of the elastic forming fabric.

Web 17 then continues around on the drier until it has made an almost complete revolution, at which time it should be dry. At this point it is removed from the surface of the drier as in machine glazing operations, or creped from the drier by some suitable means, such as a doctor knife 28, and wound onto the reel 30 so that it can be stored until ready for use.

In one satisfactory embodiment of the machine illustrated in FIGURE 1, headbox discharged stock at a consistency of about 0.2 percent onto a forming fabric having a mesh count of 50 x 52. Rolls 19 and 20 were respectively 24 inches and 28 inches in overall diameter. Rubber cover 20a was about 1 inch thick when new and of a plastometer value of about 45. In the manufacture of a web of pounds per 3000 square feet, uncreped dry basis weight, rolls 19 and were forced together under linear pressures of from 100 to 200 pounds per lineal inch and formed a nip approximately 1 to 1% inches wide.

Where a heavier basis weight web was formed, of 25 pounds per 3000 square feet uncreped dry weight, roll 19 was provided with a rubber cover about 1 inch thick when new and having a plastometer value of about 45. Linear pressures of from 150 to 250 pounds per lineal inch were applied and the nip width increased to about 1 /2 inches.

Upon leaving resilient pressure nip 18, both of the webs were at solids contents above 25 percent by weight.

In the second resilient pressure nip, the rubber cover 230 of roll 23, was 1 inch thick when new and had a plastometer value of approximately 25. The overall diameter of roll 23 was 28 inches. Linear pressure of 500 pounds per inch of machine width was applied and the nip width between roll 23 and drier 24 was from 22% inches. Upon leaving this nip, both of the webs were at a solids content of about 37 percent by weight.

Roll 25 also had a rubber cover 1 inch thick when new and having a plastometer value of about 25. Linear pressure of 5-00 pounds per inch of machine width was applied and the nip width between roll 25 and the drier 24 was from 2-2 A inches. Upon leaving this nip, the webs were at solids contents of about 40 percent by weight.

Referring now to FIGURE '2, there is shown another example of a papermaking machine embodying the invention. This machine comprises a headbox 32 adapted to discharge a continuous, uniform stream of a suitable stock suspension containing papermaking fibers onto a continuously moving forming fabric 34, of suitable mesh, adjacent to a breast roll 35. After the stock has been discharged onto the forming fabric, the latter permits sufficient water to drain so that a web 40 begins to form in the Well known manner. It may be desirable to place table rolls (not shown) or vacuum boxes (not shown) under the forming fabric following the breast roll 35 to facilitate the drainage of water from the stock suspen- S1011.

At a sufficient distance from the headbox 32 for the web 40 to reach a plastic state as distinguished from the liquid state of the stock, the forming fabric and the web pass through a resilient pressure nip 36 which removes water from the web. This nip consists of two resilient covered rolls 37 which may be provided with stationary internal suction boxes 22.

A second carrier belt 39 is provided, which may be a forming fabric or a conventional transfer felt. The carrier belt 39 and the forming fabric 34 are co-extensive through at least one resilient pressure nip 36, separated only by the wet web 40, as shown in the drawing. However, they may also be co-extensive for two or more pressure nips, depending upon the design of the particular paperma'king machine. When the two carriers are brought together, the wet web may be transferred to the carrier 39 by controlling the surface characteristics of the carriers and by the action and positioning of the suction boxes 22. At this point the forming fabric 34 may be returned over the rolls 41 to complete its circuit. As was mentioned previously, it may be necessary to include one or more conventional spreader rolls 42 in the construction of the papermaking machine to prevent wrinkling of the elastic forming fabric.

Upon leaving this resilient nip, the web 40 will follow on the under side of carrier belt 39 until it passes around the resilient surfaced pressure roll 43 where it is brought into contact with the surface of the drier 44. Other drying means of any suitable type may be provided for drying the web into a finished sheet.

As the carrier belt 39 and the wet web pass between the resilient surfaced roll 43 and the drier 44, they are subjected to heavy resilient pressure so as to insure transfer of the web to the drier and to remove additional Water from the web. At this point the carrier 39 is returned by way of the rolls 45 to complete its circuit.

After the web has made a substantially complete revolution on the drier, it is then removed and wound on a reel in a conventional manner.

In one satisfactory embodiment of the machine illustrated in FIGURE 2, headbox 32 discharged stock at a consistency of about 0.3 percent onto a forming fabric having a mesh count of 40 x 40. A Web having a dry uncreped basis weight of 25 pounds per 3000 square feet was formed.

Rolls 37 were 28 inches in diameter and were provided with rubber covers, 1 inch thick when new, having a plastometer value of 40. Linear pressures of from to 200 pounds per lineal inch were applied and formed a nip approximately 1 to 1% inches wide. Upon leaving this resilient pressure nip web 40 was above a solids content of 25 percent.

Roll 43 was 28 inches in overall diameter and had a rubber cover, 1 inch thick when new, having a plastometer value of 25. The rubber cover and shell of roll 43 were drilled to communicate with the stationary suction box 22. Yankee drier 44 was 12 feet in diameter and had a metal shell. Linear pressures of about 500 pounds per lineal inch were applied and formed a nip about 2 to 2% inches wide. Upon leaving this resilient pressure nip the web was at a solids content of about 38 percent.

A still further modification of a papermaking machine embodying the invention is shown in FIGURE 3. In this instance the papermaking machine is provided with a headbox 50 which is adapted to flow a suitable stock suspension containing papermaking fibers onto a forming fabric 52 adjacent a breast roll 54. A wet web 55 is formed by draining liquid from the stock until a plastic state is reached, as distinguished from the liquid state of the stock.

The forming fabric and the web then pass between a series of closely spaced rolls 56, 58, and 60 forming resilient pressure nips which work the wet web and which remove liquid therefrom. The rolls 56 and 60 are provided with resilient rubber covers 56a and 60a and may be drilled to communicate with stationary suction boxes 61. Roll 58 is a hard roll.

If desired, a felt 57, shown by broken lines, may be passed through these resilient nips with the web and the forming carrier to aid in water removal.

Web 55 and forming fabric 52 continue together into the resilient pressure nip formed by rolls 64 and 66, which remove additional water and which further compact and smooth the web surface. Roll 66 is provided with a rubber cover 66a and may be drilled to communi cate with suction box 61.

Forming fabric 52 returns over guide and stretch rolls 70 and desirably is prevented from wrinkling by the use of conventional spreader rolls 71.

The web 55 is further dried by heated drier rolls 72 arranged in a manner such as that shown in FIGURE 3. The drier rolls are provided with canvas belts 74 and 78 held in closely associated relationship about a part of the roll circumferences by means of the idler rolls 76. In this manner the wet web 55 is held in close contact with the drier roll surfaces and is passed from one drier roll to the next until it has been sufficiently dried. The web is then wound into a roll in a manner suitable for further use or storage.

In one satisfactory embodiment of the machine illustrated in FIGURE 3, the headbox 50 discharged stock at a consistency of about 0.7 percent onto the forming fabric 52, which had a mesh count of 42 x 45. A web having a dry basis weight of 40 pounds per 3000 square feet Was formed.

Hard roll 58 was 40 inches in diameter. Roll 56 was 34 inches in diameter overall and the rubber cover 56a, 1 inch thick when new, had a plastometer value of 40. Linear pressure of 180 pounds per lineal inch was applied with resulting nip widths of from A to 1% inches. Roll 60 was 34 inches in diameter overall and the rubber cover 60a, 1 inch thick when new, had a plastometer value of 45. Linear pressure of 200 pounds per lineal inch was applied with resulting nip widths of from 1 to 1 /2 inches. The web leaving these resilient pressure nips had a solids content above 30 percent.

Hard roll 64 had a diameter of 40 inches. Roll 66 was 34 inches in diameter overall and the rubber cover 66a, 1 inch thick when new, had a plastometer value of 45. Linear pressure of 225 pounds per lineal inch was applied with resulting nip widths of from 1 to 1 /2 inches. Upon leaving this nip the web had a solids content above 35 percent.

In the operation of each of the machines described in the foregoing, the forming fabric and the web pass through at least one resilient pressure nip wherein the forming fabric and the web are elongated at least 0.5 percent while subjected to a peak pressure of at least 100 pounds per square inch. This accomplishes the primary objectives of the invention.

The obtaining of the critical amount of elongation can be accomplished by adjustment of a number of variables, such as the plastometer value of the resilient roll coverings, the thickness of the resilient coverings, the roll dimeters, and the like. The applied linear pressure is subject to machine adjustment to attain the desired critical value of peak pressure. It will be evident that adjustment of the linear pressure will also affect the elongation and interrelated adjustment of both values will be found necessary in the usual instances. The amount of elongation and the peak pressures for any given roll combination may be readily determined by calculation or by measurement.

In the design of specific roll combinations operable to provide resilient pressure nip characteristics in accordance with the invention, roll coverings having plastometer values within the range of 20 to 70 will be found suitable. Roll coverings having plastomer values within this range can be used with hard-surfaced rolls or with cooperating resilient rolls to produce the desired elongation and peak pressure without excessive or difiicult to obtain linear pressures.

Plastomer values given in this specification are determined with a standard instrument using :a /8 inch diameter ball under one kilogram load according to A.S.T.M. Procedure D53l49, as is well understood in the papermaking industry.

The invention provides important advantages over the prior art practices. For example, the invention makes possible the elimination of various heretofore necessary machine elements of substantial capital cost, such as the felt pickup apparatus, and other auxiliary carrier systems. As a result, one of the salient features of the invention is a simple and compact papermaking machine as compared to the prior art machines. The invention also minimizes machine operating expenses such as the replacement and maintenance of felts in various locations on the machine.

In the practice of the invention, the solids content of the web is raised to a value in excess of 25 percent, and preferably in excess of 35 percent, while the web is on the forming carrier. This has important advantages in the improvement of the final paper product. The liquid removal making possible these ranges of solids contents is achieved by carrying the wet web while on the forming fabric through at least one resilient pressure nip of the defined type. As theweb and forming fabric pass through the resilient nip, in addition to being worked, the web is pressed and water is removed. After it leaves the carrier, the web is dried and wound in a roll suitable for storage purposes or further processing.

The invention is especially adapted to the formation of webs from hydrated fibers such as conventional papermaking fibers which bond initially by surface tension effects and which proceed to develop additional strength by inter-fiber bonding as water removal and drying progress. This includes hydrated or bonding types of synthetic fibers as well as natural fibers. The use of non-bonding synthetic fibers should 'be avoided unless special adhesives, binders, or bonding fibers are present in the furnish to provide wet and dry strength beyond the point where surf-ace tens-ion bonding diminishes.

Although certain embodiments and terminology have been used in the specification, it is to be understood that these are merely by way of example and are to be construed in no manner as limitations. It is contemplated that certain modifications may be made within the scope of the claims without departing from the spirit of the invention.

I claim:

1. In combination in a paperrnaking machine, an elastic forming carrier of synthetic fiber, means for supplying -a stock suspension of fibrous material suitable for making paper to said forming carrier, said forming carrier being arranged to effect drainage of liquid from said stock suspension to form a Wet web of fibrous material on one surface thereof, and at least one pair of pressure rolls which provide a resilient pressure nip through which said forming carrier and the wet web formed thereon are caused to move during the operation of said machine thereby incrementally deforming said carrier and corresponding increments of the Web and substantially reduc= ing the moisture content of the web.

2. In combination in a papermaking machine, means for supplying a stock suspension of fibrous material suita-= ble for making paper, an elastic forming fabric of syn thetic fiber associated with said supply means for receiving said stock suspension therefrom, and at least one pair of pressure rolls spaced from said supply means and forming a resilient pressure nip, said pair of pressure rolls comprising at least one roll having a jacket constructed of a deformable, resilient, noncompressible material, said forming fabric being adapted to permit the formation of a wet web of said fibrous material and being adapted to carry the wet web through said pressure nip, whereby at least part of the residual liquid in said wet web is squeezed therefrom as a result of the application of pressure and the momentary elongation of said forming fabric and the web occurring incident to passage of said forming fabric and the web through said pressure nip.

3. A papermaking machine comprising an elastic forming fabric constructed of synthetic fiber, means for supplying a stock suspension of fibrous material suitable for making paper to said forming fabric, said forming fabric adapted to permit formation of a wet web of said fibrous material, at least one pair of pressure rolls spaced from said means and forming a resilient pressure nip, said pair of pressure rolls comprised of at least one roll having a jacket constructed of a deformable, resilient, noncompressible material, said forming fabric adapted to carry the Wet web through said pressure nip, at least one of said pairs of pressure rolls having a peak nip pressure of at least 100 pounds per square inch whereby an increment of said forming fabric and a corresponding increment of the wet web are momentarily elongated at least 0.5 percent while passing through said resilient pressure nip, and drying means, said forming fabric being adapted to bring the web into contact with said drying means whereby the web is transferred thereto.

4. In combination in a papermaking machine, an endless elastic forming carrier, of synthetic fiber, means for supplying a stock suspension of fibrous material suitable for making paper to said forming carrier, drive means for continuously moving said forming carrier, means for delivering continuously a stream of said stock suspension to said forming carrier whereby a continuous, Wet web of said fibrous material is formed on one surface of said forming carrier, at least one pair of cooperating pressure rolls spaced from said stock supply means, at least one of said rolls having a jacketconstructed of a deformable, resilient, noncompressible material, means conducting said forming carrier and the web formed thereon through the resilient nip produced by said coop-v erating pressurerolls during the operation of said machine, and means forcibly urging said pressure rolls toward each other, the forces exerted by said means urging stock suspension to form a continuous, Wet web of said fibrous material on said moving carrier, continuously conducting said web, while it is on said carrier, through a region wherein there is produced in an increment of said carrier and a corresponding increment of said web a momentary elongation of at least 0.5 percent, while simultaneously subjecting the carrier and the web thereon to a pressure of at least 100 pounds per square inch, thereby substantially increasing the solids content of the web, and finally drying said web.

7. The method of making paper which comprises the steps of flowing a stock suspension of fibrous material onto a moving, elastic foraminous carrier of synthetic fiber, draining suflicient liquid from said stock suspension to form a continuous Wet web of said fibrous material ion a surface of said moving carrier, continuously conducting said web, while it is on said carrier through at least one resilient pressure nip, whereby there is produced continuously in an increment of said carrier and in the corresponding increment of said web carried thereon a momentary elongation of at least 0.5 percent, while simultaneously subjecting the carrier and web to a pressure of at least 100 pounds per square inch, thereby substantially increasing the solids content of the web, and finally drying the web.

8. The method of making paper, which comprises the steps of delivering a flowing stream of a stock suspension of papermaking fibers to a continuously moving, elastic foraminous carrier of synthetic fiber, draining sufficient liquid from the stock suspension delivered to said carrier to form a wet web of fibers on said carrier, con ducting said wet web while it is on said carrier through at least one pressure zone which momentarily deforms said carrier and the web thereon so as to remove sulficient liquid from said web to increase the solids content thereof to at least 25 percent by weight, and finally drying said web.

9. The method of making paper, which comprises the steps of delivering a flowing stream of a stock suspension of papermaking fibers to a continuously moving,

elastic foraminous carrier of synthetic fiber, draining suificient liquid from the stock suspension delivered to sm'd carrier to form a wet Web of fibers on said foraminous carrier, momentarily elongating said carrier and the web thereon by conducting said carrier and the wet web thereon through at least one resilient pressure nip which is effective to remove sufficient liquid from said web to said pressurerolls toward each other being so adjusted relative to the resilient characteristics of said rolls that said carrier and said web are incrementally elongated at least 0.5 percent and are subjected to "a peak pressure of at least 100 pounds per square inch while passing through said resilient pressure nip. 5. A papenmaking machine as defined in claim 4 which is provided with a plurality of pairs of cooperating pressure rolls arranged to provide a series of sequentially arranged, resilient, pressure nips, each having the characteristics set forth in claim 4, and wherein said sequentially arranged pressure hips are adapted to subject the carrier and web to progressively increasing pressure during the passage of the carrier and web therethrough so as to in crease the solids content of the web to at least 35 percent. 6. The method of making paperwhich comprises the steps of flowing a stock suspension of fibrous material onto a continuously moving, elastic foraminous carrier of synthetic fiber, draining sufficient liquid from said increase the solids content thereof to at least 25 percent by weight, and finally drying said web.

10. The method of making paper which comprises the steps of delivering a flowing stream of a stock suspension of papermaking fibers to a continuously moving, elastic foraminous carrier of synthetic fiber, draining sufficient liquid from the stock suspension delivered to said carrier to form a wet web of fibers on the foraminous carrier, momentarily elongating an increment of said,

carrier and a corresponding increment of said wet web by conducting said carrier and the wet web thereon through at least one resilient pressure nip to press residual liquid from said web so as to increase the solids content thereof to at least 35 percent by weight, and

finally drying the web.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

10. THE METHOD OF MAKING PAPER WHICH COMPRISES THE STEPS OF DELIVERING A FLOWING STREAM OF A STOCK SUSPEN SION OF PARPERMAKING FIBERS TO A CONTINUOUSLY MOVING ELASTIC FORAMINOUS CARRIER OF SYNTHETIC FIBER, DRAINING SUFFICIENT LIQUID FROM THE STOCK SUSPENSION DELIVERED TO SAID CARRIER TO FORM A WET WEB OF FIBERS ON THE FORAMINOUS CARRIER, MOMENTARILY ELONGATING AN INCREMENT OF SAID CARRIER AND A CORRESPONDING INCREMENT OF SAID WET WEB BY CONDUCTING SAID CARRIER AND THE WET WEB THEREON THROUGH AT LEAST ONE RESILENT PRESSURE NIP TO PRESS RESIDUAL LIQUID FROM SAID WEB SO AS TO INCREASE THE SOLIDS CONTENT THEREOF TO AT LEAST 35 PERCENT BY WEIGHT, AND FINALLY DRYING THE WEB.

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