US2756651A - Papermaking machine - Google Patents

Description

July 31, C. A. LEE PAPERMAKING MACHINE Filed OCT.. l5, 1949 3 Sheets-Sheet 1 July 31, 1956 C A LEE PAPERMAKING MACHINE 5 Sheets*Sheet 2 Filed OCT.. l5, 1949 'JQQ July 31, 1956 c. A. LEE v 2,756,651

PAPERMAKING MACHINE l 1 Filed oct. 15, 1949 s rsheets-smeet a @om ,0010( //o//vegy/J United States Patent O ments, to Kimberly-Clark Corporation, a corporation of Delaware Application October 15, 1949, Serial No. 121,525

4 Claims. (Cl. 92-44) The present invention relates generally to the manufacture of paper, and has particular relation to Fourdrinier papermaking machines of the inlet or pressure-forming type, i. e. to papermaking machines wherein the stock is supplied to a web-forming region on a Fourdrinier wire as a relatively high energy, flowing stream, which may be under considerable hydraulic pressure.

Prior to the development of the inlet or pressureforming type papermaking machine, it was the general practice in the operation of Fourdrinier machines to form the mat of iibers of which the paper web is composed by applying to the upper surface of the Fourdrinier wire, as by owing thereon, a layer of paper stock containing the required amount of fiber in an amount of water which was suiicient to produce the proper distribution of the fibers in the Web, and to subsequently eliminate sufficient of the water to produce a coherent web or sheet which was capable of being couched-oif the end of the Wire. Various arrangements, including suction boxes, table rolls and doctors, were disposed beneath the wire for increasing the drainage therethrough, and since there was no substantial pressure differential in the web-forming region along the wire, the speed of operation ofthe machine was determined primarily by the capacity of the drainage means.

In contrast with this, in inlet or pressure-forming machines, examples of which are shown in U. S. Patents No, 2,060,808, 2,264,941 and 2,308,370, the stock is applied to a narrow section of the wire as a coniined, relatively high energy, owing stream, usually under substantial hydraulic pressure, and a large proportion of the water in the stock mixture is thereby forced through the wire in this region. This arrangement makes possible very high speed operation of the machine, since it becomes possible to eifect the drainage of a very large percentage of the water from the Web in a very short interval of time. In addition, since the web-forming region occupies a relatively short portion of the length of the Fourdrinier wire, it makes possible the provision of papermaking machines which can be operated at very high speeds with comparatively short forming-Wires. Also, the arrangement makes possible improved formation, since the stock may be used at very low consistencies, and is subject to more effective control.

Because of these advantages, a relatively large number of pressure-forming or inlet-type machines have come into use in the papermaking industry. However, certain ditticulties have arisen in the operation of these machines, especially when they are operated at extremely high rates of speed, i. e. speeds in excess of 1500 to 2000 ft. per minute. Particularly, it has been observed that cyclic or intermittent conditions of flow instability sometimes develop within the inlet adjacent or in the Web-forrning region, and these instabilities tend to produce vibration of the wire in, or adjacent to, the Web-forming region (and other conditions) which result in variation in the Weight of the sheet being manufactured, along the length thereof. In some instances, this weight variation is of at the other end by the usual couch roll.

2,756,65l Patented July 31, 1956 ICC suicient magnitude to produce visible, transverse bars, which are very objectionable in the finished sheet. The vibration of the wire induced by the instability conditions above described, has the further disadvantage that it may materially reduce the life of the wire, and may cause Wear at the lip of the slice. As previously noted, these conditions of instability become particularly noticeable at higher speeds, and to that extent, the development of inlet-type machines has not progressed to the extent originally anticipated.

The present invention has for its principal object the provision of an inlet orl pressure-forming papermaking machine, which shall be free from this operational diiculty. More specifically, it is an object of the invention to provide an inlet or pressure-forming papermaking machine which can be operated at very high speeds, without the development of either transient or sustained conditions of flow instability in the web-forming region.

In the usual pressure-forming or inlet machine, the Fourdrinier or forming wire is supported adjacent the stock delivery end of the machine by a breast roll and The breast roll may be solid or reticulated. The stock is delivered to the web-forming region of the wire, which in machines having a solid breast roll, is usually immediately forward of the center line of the breast roll, by a conduit system which provides, in effect, a discharge spout having an outlet which is substantially co-extensive with the Webforming region on the wire. During operation, the delining walls of the spout are in very close proximity to the wire and the stock is supplied to the discharge opening under substantial pressure. As a result of this arrangement, it is possible to impress the flowing stream of stock onto the wire as a high-energy, flowing stream and to accomplish drainage of the stock liquid, with substantially complete formation of the web within the web-forming region, which, as previously stated, is coincident with the outlet opening of the stock delivery system.

To aid in directing the flowing stream of stock through the wire, the earlier inlet machines were provided with an apron of flexible material which rested on the Wire and the breast roll, so as to provide a seal at the bottom of the stock delivery conduit. The machines also included end seals which contacted the wire at the sides of the webforming region. In later constructions, an apron plate having a lip section which extends in close proximity to the moving wire was used inplace of the llexible apron, this arrangement avoiding apron wear and the other` diiculties incident to the use of aprons. A slice, which may constitute a vertically or angularly disposed wall, and which is positioned with one edge thereof almost in contact with the web formed on the wire, has been generally used to define the other surface of the stock outlet opening, and the Web-forming region.

Inlet or pressure-forming machines in accordance with the present invention are, in general, similar to these prior arrangements. That is to say, these machines include a breast roll support for the wire and means for delivering the stock, as a relatively high-energy stream, to a web-forming region of limited area, which, for a solid breast roll machine, is conveniently located on the wire immediately forward of the center line of the breast roll. The stock delivery means comprises a conduit or head box having side walls, a bottom, and a slice which is adapted to extend across and in close proximity to the wire at the downstream edge of the Web-forming region. Also, the stock supply means includes end seals at the sides of the web-forming region, which confine the stock to the wire Width.

However, in contrast to the prior arrangements, where the bottom of the stock supply conduit is defined by an apron which actually contacts the moving Wire, or by an apron plate which extends in close proximity to the moving wire, so as to confine the flowing stream of stock to the web-forming region on the wire, and thereby prevent, or at least restrict insofar as possible, any ow of stock backwardly along the moving wire and breast roll, the structure of the present invention contemplates, and provides for, a continuous, stable, flow of stock backwardly along the wire and breast roll ahead of the web-forming region. In other words, the stream of stock delivered to the web-forming region is divided into two portions; one of which (the major portion) passes through the wire at the web-forming region, and the other of which flows backwardly, under stable-flow conditions, along the forwardly moving wire before the wire moves into the web-forming region. In order to assure the attainment of stable-flow conditions in the backwardly owing portion of the stream, the amount of stock in that stream should constitute a substantial portion of the total stock delivered by the stock supply means, and it is important to note that this is an almost complete divergence from the prior teachings in this general field. Some backflow has existed in the prior machines equipped with apron plates, but in general, every effort has been made to minimize the amount of such tlow. Conveniently, this stable, backward flowing stream of stock is created by using an apron plate on the bottom of the stock supply conduit, which is cutback a substantial distance from the web-forming region, and which is spaced a suiiicient distance from the wire and breast roll to assure the maintenance of stable-flow conditions in the backwardly owing stream under all possible conditions of machine operation.

When stable-ow conditions are present in the backwardly flowing stream of stock, it will be observed that corresponding stable-how conditions will exist Within the stock supply conduit for at least a substantial distance upstream of the web-forming region. Thus, a convenient index for determining when the desired steadyflow conditions exist in the backwardly owing stream can be provided by combining a pressure tap placed in this conduit with a pressure indicating means capable of recording pressure variations at a cyclic frequency as high as about fifteen cycles per second. Specifically, when the apron plate is cut-back the proper amount, it will be observed that pressure variations within the ow conduit will be reduced to a very low value and provide that this condition persists over the operating range of the machine, it may thereby be assumed that stable-How has been realized, both in the backwardlyflowing stream and in the main stock supply.

Considered from a theoretical viewpoint, the provision of a stable, backwardly owing stream of stock along the ascending wire and breast roll (with corresponding stable flow within the stock delivery conduit and the web-forming region) indicates that a stagnation point which is at least substantially stable in character, or line of stagnation points, has been created ahead of the lip of the apron plate, in the flowing stream of stock at the delivery end of the stock conduit system, i. e. in the portion of the outlet of the stock discharge conduit which is upstream of the web-forming region. Thus, any means which will produce a line of generally stable stagnation points in incremental, transverse, vertical cross-sectional areas across the flowing stream of stock in this region will accomplish the desired stabilization of flow and, hence, will accomplish the objects of the invention. The most convenient method of attaining this condition is by the use of an apronplate having a cut-back lip, but it will be understood that the invention is not limited to this particular arrangement.

Certain exemplary embodiments of the invention, as applied to pressure-forming or inlet type machines of various types, are illustrated in the accompanying drawings, wherein:

Figure l is a schematic view, partially in side elevation and partially in vertical section, of the wet-end of a Fourdrinier inlet type papermaking machine, embodying certain of the features of the invention, and certain accessory equipment therefor;

Figure 2 is an enlarged, vertical cross sectional view of the delivery portion of the stock supply means and the web-forming region of the machine illustrated in Figure l;

Figure 3 is an enlarged, sectional view, generally similar to Figure 2, of a second inlet-type machine in accordance with the invention;

Figure 4 is an enlarged, sectional view of an end seal for the web-forming region, suitable for use in conjunction with the inlets illustrated in Figures 2 and 3; the view is taken on the general line 4 4 of Figure 2;

Figure 5 is a cross-sectional view of a pressure forming papermaking machine, wherein the stock supply system includes a headbox; and

Figure 6 is an enlarged, fragmentary view of the web-forming region of the machine illustrated in Figure 5.

The diagrammatic view, Figure l, illustrates the general arrangement of a pressure-forming inlet machine of the type to which the present invention particularly pertains. As there shown, the Fourdrinier wire 11 is supported upon a suitable solid-type breast roll 13 and a couch roll 15, and is arranged to pass over a plurality of spaced, table rolls 17 and suction boxes 19. The wire 11 is tensioned by additional guide or tensioning rolls, such as the roll 21. A tray 23 which is adapted to collect the white-water (i. e. the liquid portion of the stock which is drained through the wire) is disposed within the upper and lower passes of the wire Z1, as illustrated, and this tray 23 is arranged to discharge into a mixing tank 25 which is normally maintained about three-fourths filled. Fresh water for makeup purposes may be added to the mixing tank 25 through the pipe 27, and additional stock, as is necessary to maintain the proper consistency of the stock delivered to the web-forming region, is added through a suitable stock inlet pipe 29.

The bottom of the mixing tank 25 is inclined, as shown, and a main flow line 31 connects to the tank at the lower end thereof. The main ow line 31 includes a valved branch 33 for use in draining the mixing tank, and this valved branch also connects with the inliow end of a stock or fan pump 35, which is the principal means relied upon to deliver stock to the web-forming region. The outlet of the fan pump 35 is connected to the inlet structure by suitable piping, as indicated generally at 37. Included in this piping is a iiow spreader, indicated at 39, which accomplishes the function of converting the uniformly dimensioned stream delivered by the pump 35 into a relatively shallow stream of rectangular cross section having a width substantially equal to the width of the stock passage or flow conduit 41 through the inlet structure, which is also substantially equal to the width of the web-forming region of the machine. Suitable showers or sprays, as indicated generally at 40 are provided for effecting continuous cleaning of the rolls and wire in accordance with usual papermaking practice.

The inlet itself comprises a pair of stationary side frames 43 (Fig. 2) which support a pair of spaced-apart, vertical walls 44, which are desirably fabricated of plate sections and are formed with flanges on their lower edges in order that they may be securely clamped to the side frames 43. Secured in a liquid-tight manner to and between the side walls are curved upper and lower plates 45 and 46, which define, with the side walls 44, the inlet passageway or conduit 41, which in side elevation is of generally gooseneek form. The inlet conduit 41 is rectangular in cross section, and the inflow end thereof has the same dimensions as the outlet end of the flow spreader 39. Conveniently, the inlet conduit 41 is of generally uniform cross sectional area, and to avoid fouling of the interior tle'reof, the exposed surfaces desirably are made of stainless steel or equivalent material.

Extending between and connecting the side frames 43 is' a cross beam 47, which in addition to strengthening the inlet structure, serves as an adjustable support for an apron plate 49, the upper surface of which constitutes a portion of the lower defining surface of the inlet conduit 41. The apron plate 49 merges smoothly into the other dening elements for the lower portion of the inlet conduit, and together with the beam support 47 therefor, may be moved toward and away from the breast roll 13. The lip portion S1 of the apron plate 49 is tapered as illustrated, the under-surface of the lip portion 51 being desirably curved so as to provide, with the adjacent surface of the wire 11 on the roll 13, a passageway 53 of increasing cross sectional area in the direction opposite the direction of movement of the wire 11.

The side walls 44 of the inlet structure are connected at the outilow end of the inlet conduit 41 by a rigid, hollow beam 55. The beam 55 also serves as a support for a support bracket 57, which in turn supports a slice or nozzle plate 59, which is hingedly connected to the bracket by a suitable hinged connection, indicated generally at 61. The forward edge of the slice plate 59 is connected to a plurality of spaced-apart combination lift and adjusting rods 63, which are arranged to be operated in unison by a motor-driven mechanism, illustrated in outline at 65. The arrangement is such that the slice plate 59 and the associated lift rods 63 can be moved, as a unit, toward and away from the Wire by simultaneous operation of the motor-driven mechanism 65, and in addition, the forward edge of the slice can be locally adjusted across the width of the machine by the screw adjusting means incorporated into the lift rods. A perforated distributor roll 67, which can be rotated at controlled speed by a motor-operated drive mechanism 69, is positioned within the inlet 41, adjacent the web-forming region.

During normal operation of machines of this type, the pressure and velocity relationships in the stream of stock supplied to the inlet conduit 41 are so regulated that such stock as is discharged from the web-forming region beneath the lip of the slice will have a spouting velocity approximately equal to the speed of the forming wire 11. In addition, in order that the web-forming operation shall be substantially complete within the contines of the inlet, the machine is normally operated with the forward edge of the slice plate 59 almost in contact with the web being formed on the wire 11, and it is this mode of operation which particularly characterizes pressure-forming or inlet type machines. The volume of the stock which is forced through the wire in the web-forming region of the inlet is determined almost entirely by the area of wire exposed to the stock in that region, assuming all other factors, such as pressure and stock consistency, are maintained substantially constant.

In order to conne the sides of the flowing stream of stock delivered to the web-forming region, suitable endseals are provided at each side of the stock delivery conduit 41. Conveniently, each of these seals includes a plate 71 which is attached to the slice, so as to constitute an extension of the side walls 44 of the inlet, and a resilient shoe 73, which is supported on the plate 71 and which is adapted to ride on the outer edges of the wire 11 adjacent the web-forming region.

A suitable end-seal arrangement of this general type is illustrated in Figure 4, wherein a suitable shoe 73 which comprises a sheet rubber bearing section 75 and a sponge rubber backing portion 77 is shown in position to contact the outer edges of the wire 11 during normal operation of the machine. The sponge rubber backing portion 77 of the sealing shoe 73 is held in operative position by an angle member 79, which in turn is fastened to the seal plate 71 or equivalent means by screw fastenings 81, as shown. The use of a resilient end-seal of this nature is particularly important in pressure-forming machines not only because of. the sealing function accomplished, but also for the reason that the relatively high pressures developed, which depress the` wire in the Web-forming region, would otherwise result in a material deformation of the edge portions of the wire, capable of seriously damaging the Wire.

The depression of the wire in the web-forming region also makes it desirable that the apparatus include means for rapidly raising the slice in the event that pressure is removed from the inlet. The details of one satisfactory means of accomplishing this is illustrated in U. S. Patent No. 2,308,370, and since this, or equivalent mechanism is conventional equipment for use in pressure-inlet machines, it will not be described in detail.

ln the illustrated structure, it will be noted thatthe downstream edge or lip portion 51 of the apron plate 49 is cut-back up-stream of the center line of the solid breast roll 13 a suicient distance, and the undersurface of the lip 51 is so proportioned, that the passageway 53 formed between the under-surface of the lip portion 51 and the wire 11 is of substantial cross-sectional area, as compared with the total area of the web-forming region. VAs previously pointed out, the dimensions of the passageway 53 should be such that a portion of the owing stream of stock delivered through the inlet conduit 41 will flow through this passageway, in a direction opposite to the direction of wire movement and under conditions of stable-` flow, at all times during the operation of the machine.

This relative proportioning of the structural elements of the machine, with the resultant production of a stable, backwardly-owing stream of stock in the region where the wire moves into theweb-forming'region, effectively eliminates the instability conditions previouslyobserved in the operation of machines of this type. The arrangement not only improves the quality of paper made on the machines, but in addition, it makes possible operation at much higher speeds than has heretofore been attainable, even in pressure-forming type machines.

As previously pointed out, the presence of astable, backwardly owing stream of stock in the Vregion where the wire moves into the web-forming Vregion indicates that a stable stagnation point exists in each of the incremental, cross-sections of the flowing lstream of lstock across the width of the machine, in the region between the lip of the apron plate and the downstream edge of the stock discharge passageway, i. e. the lip of the slice. Moreover, once stable-How conditions are realized, this stagnation point, or line of stagnation points, for a givengset of operating conditions, will remain substantially fixed in position with the result that once the proper positioning of the lip 51 ofthe apron plate 49 has been determined, further adjustment will not ordinarily be required.

The amount of stock which is discharged in the backward direction through the passageway 53 may constitute a relatively substantial proportion -ofthetotal stock delivered to the machine. For example, amounts up to forty or even fifty percent of the total flow have been observed in the operation of certain machines. However, the character of the flow rather than the amount is the critical factor in assuring reliable operation of the machine.

When the backward flowing stream of stock isprovided by cutting back the lip of the apron plate, a trial and error procedure for locating the lip position will usually be found most convenient, although the location of the lip can be determined by computation. The trial and error procedure is particularly facilitated by virtue of the fact that the existence of stable-flow conditions in the backwardly owing stream is accompanied by corresponding stable-flow conditions within the inlet conduit. Thus, as previously suggested, a pressure tap may be provided in the inlet conduit (as, for example, as shown at 80 in kFigure 2), and the location of the cut-back lip determined by reference to the pressure c'onditionslwithin 'the inlet conduit, as ascertained by use of such tap. Since, the proper position of the lip will be lindicated by the absence of substantial pressure variations within the inlet conduit, this properposition for the lip can readily be reached by granular step-wise cutting-back or movement f the apron plate. It is also possible to determine the proper position of the cut-back lip by means of a model study.

In positioning the apron lip to obtain stable-flow conditions in the backwardly flowing stream, it may sometimes 'be found advantageous to adjust the relative vertical position of the apron lip and breast rol'l. This is easily accomplished in almost any of the known types of pressure-forming papermaking machines, since substantially all such machines include built-in means for raising or lowering the breast roll to adjust its position.

When the invention is used in conjunction with machines of the solid breast roll type, the apron lip will be cut-back to a point Where the edge of the apron lip is upstream of the center-line of the roll. In machines using reticulatcd or similar type breast rolls, the position of the apron lip will be determined by the location of the web-forming region and the general structural arrangement of the parts.

Regardless of the type of breast roll used, prov-ision should be made for preventing the deposition of fibers onto the wire preliminarily to the passage of the wire into the web-forming region. In other words, the web should be formed entirely within the web-forming region, and no ber should be deposited on the wire from the backwardly flowing stream provided in the practice of the present invention. When the machine includes a solid breast roll, no dificulty will be experienced in preventing iiber deposition ahead of the web-forming region, due to the normal entrainment of shower water in the wire, and 'between the wire and the roll surface. However, When a re'ticulated breast roll is used, it will generally be found desirable to provide means, such as a water box or shower within the roll, for producing a flow of water outwardly through the wire, in the region ahead of the web-forming region, of sufficient volume to prevent fiber deposition ahead of the web-forming region.

The advantages of the invention are not limited to pressure-forming or inlet machines of the type illustrated in Figures l and 2. However, the invention will be found of particular advantage in pressure-formed machines, wherein the total available energy in the flowing stream -of stock delivered to the pressure-forming region is equivalent to a hydraulic head which is in excess of about l inches of water. For pressures and operating speeds substantially less than these values, the instability conditions which the invention corrects usually are not seriously troublesome.

As an example of other pressure-forming type machines, wherein the invention may be used, a second inlet machine is shown in the sectional view of Figure 3. In the machine illustrated in this figure, the inlet conduit 83 is of substantially less depth than is the case in the Figure 2 machine, and the upper defining wall 85 of the conduit extends in close proximity to the upper surface of the distributor roll 87. Also, a vertically adjustable slice 89 is employed at the outlet end. Similarly to the Figue 2 structure, the side walls of the inlet conduit 83 are defined by suitable side plates 91 which are supported upon the upper edges of side frames indicated generally at 93. The lower defining wall of the conduit 83 includes a curved plate member 95, as shown, a bottom plate 97, and an apron plate 99, which is affixed to a suitable support plate 101 attached to the side frames 93.

The vertically movable slice 89 is adjustably supported upon suitable, transverse members, which may include a beam 103 generally similar to the beam 55, and a bracket 105, generally similar to the bracket 57, which extends between the side plates 91. End seals 107, which may be of the same general type shown in Figure 4 are provided for confining the edges of the flowing stream of stock to the web-forming region. Portions of the breast roll and the forming wire are illustrated at 109. and 111, respectively.

As in the previously described pressure-inlet machines, the lip 113 of the apron plate 99 is tapered and is cut back from the conventional position, so as to provide a passageway 115 of substantial dimensions between the lower surface 0f the lip 113 and the adjacent surface of the wire 111. The dimensions of the parts are correlated so that the flowing stream of stock passing through the inlet conduit S3 divides adjacent lthe lip 113 of the apron plate 99, and a substantial portion of that stream ows through the passageway 115 as a stable-flowing stream, in a direction opposite to the direction of movement of the wire, under the various operating conditions of the machine. The same benefits of greatly increased stability and improved machine operation, with a complete avoidance of transverse bars in the finished sheet, especially at higher speeds, are obtained.

Various headbox machines may be operated in the manner of pressure-forming machines, and an example of such a machine is shown schematically in Figure 5. As there illustrated, stock from a suitable source of supply, which may comprise a plurality of screens, is delivered, via a suitable trough 117, to a downwardly flowing conduit 119 at the inflow end of a headbox. The outlet end of the conduit 119 connects with a flow spreading passageway 121 defined between the end wall 123 and the bafe 125. After passing over the bafe 125, the stock flows into the ponding chamber proper 127 of the machine. Within the pending chamber 127 there are provided two vertically adjustable baffles 129 and 131, which permit substantial adjustment of the stock level with or without throttling, as may be desired. One or more distributor rolls, as illustrated at 133, may be provided within the ponding chamber.

The wire is supported on a breast roll 137 adjacent the discharge end of the headbox, and the stock is delivered through a nozzle or outlet structure 139 to a web-forming region on the wire as a high-energy, flowing stream. The upper surface of the outlet 139 is defined by an adjustable slice 141; the lower surface is defined by an apron plate 143 and suitable end-seal means 145, not shown in detail, are provided at the two ends of the outlet. Similarly to the previously described structure, a passageway 147 is provided between the lower surface of the apron plate 143 and the wire 135, and the relative dimensions of the parts are so correlated that a substantial portion of the stock delivered through the machine outlet 139 flows in a stable, flowing stream through the passageway 147 in a direction opposite to the direction of movement of the wire for the various operating conditions of the machine.

In the foregoing, I have disclosed certain structural arrangements and operational procedures whereby the operation of pressure-forming papermaking machines of the inlet or other types can be substantially improved. Specifically, I have disclosed that a stable, flowing stream of stock, which may constitute a substantial portion of the stock delivered to the machine, should be caused to flow backwardly along the forwardly moving formingwire, immediately ahead of the web-forming region, and that when such a stable-flowing stream exists, important improvement in the operation of the machine, especially at high speeds, will result.

As above pointed out, the existence of this backwardlyflowing, stable stream of stock creates a line of stagnation points extending across the machine within the confines of the stock discharge opening, with the result that the instabilities previously noted during the operation of pressure-forming machines, especially at high speeds, are effectively eliminated. Thus, by the use of the invention, it becomes possible not only to avoid certain operational` 9 difficulties previously experienced with this type machine, but in addition, it becomes possible to operate the machines at much higher spe: :is than has heretofore been believed possible of attainment.

forming region are eliminated and there is produced thereby producing a condition of stable fiow within the stream of stock reaching the forming wire in the webforming region.

In accordance with the usual definition of the term, 6 4. In a papermaking machine of the pressure-forming flow is stable in the sense intended herein when there type, a source of supply of stock, means for delivering a is no substantial variation in the mean velocity and no fiowing stream of stock under pressure to the web-forming substantial variation in the mean pressure, with respect to region of said machine, said stock delivery means includtime, at any given point in the fiowing stream. ing means which defines the walls of an enclosed flow Various of the features of the invention believed to 10 conduit and said web-forming region being located at the be new are set forth in the appended claims. discharge end of said conduit, a forming wire, and means I claim: for supporting said wire and for moving said wire across 1. In a papermaking machine of the pressure forming the discharge end of said conduit in close proximity to type, a source of supply of stock, means for delivering a the defining walls thereof, whereby the web is formed on fiowing stream of stock under pressure to the web-forming said Wire in said region underpressure-forming condiregion of said machine, said stock delivery means inc1udtions, Said Waii defining ineans including a bottoni Piate ing means which defines the Walls 0f an enclosed 110W which defines the bottom wall of said conduit, said bottom conduit and said web-forming region being located at the Piate eXtending trarisVerseiY across said inaehine adjacent discharge end of said conduit, a forming wire, and means said Wire arid having a iiP on its forward edge Which is for supporting said wire and for moving said wire across spaced from, and is so Positioned reiatiVe to, Said Wire the discharge end of said conduit in close proximity to aS Said Wire Passes through said Web-forming region at the defining walls thereof, whereby the web is formed the discharge end of said conduit that there is continuous, on said wire in said region under pressure forming condi- Stable oW of stoek through the discharge outlet of Said tions, said wall-defining means including a section which Condi-lit baCiWardiY along said Wire, away frorn Said Webis spaced from, and is so positioned relative to, said wire forming region, thereby to effect the eilmillatlOIl 0f Subas Said Wire passes through Said Web forming region at stantial pressure fluctuations in the iiowing stream of stock the discharge end of said conduit that there is continuous, reaching s aid Web-forming region during the operation of stable flow of stock through the discharge outlet of said said machineconduit backwardly along said wire, away from said webforming region, thereby to effect the elimination of sub- References Cited m the me of this Patent stantial pressure fiuctuations in the flowing stream of stock UNITED STATES PATENTS reaching s aid Web-forming region during the operation of 809,073 McNaught Jan. 2 1906 sa1d machine' 1,898,372 Hyde Feb, 21, 1933 2. A papermaking machine as defined in claim l, 1 928 107 Lang Se t 26 1933 herein said stock delivery means is operable to deliver p W 2,060,808 Kenai et ai. Nov. 17, 1936 the flowing stream to the web-forming region under such 2 148 613 Frost Feb 28 1939 conditions of pressure and velocity that the total avail- 2202j890 Berry Iulle 4 1940 able energy 1n sa1d stream is in excess of a hydraulic head 203,802 Thaler June 11! 1940 equivalent to about 25 luche? of Water o 2,264,941 Keilett et al, Dec, 2J 1941 3 The method 91 Operatmg a papermaklrig machine of 2,344,282 Berry et al. Man 14, 1944 the pressure forming type, wherein a flowing stream of 2 384 912 Henn Se t 18 1945 stock is del1vered, under pressure, by way of an enclosed 2,473,069 Niks June 14J 1949 conduit t0 a web-forming region located at, and substan- 2,550,552 Goodwiuie Apr' 24, 1951 tially co-extensive with, the outlet end of sa1d conduit, 2,664,033 Hombostel et al 1966.29 1953 and wherein a forming wire is moved across the outlet end of said conduit in close proximity to the defining walls FOREIGN PATENTS thereof lduring the web-forming operation, which com- 16,546 Great Britain Aug. 22, 1890 prises directing a major portion of the fiowing stream of 356,294 Great Britain Sept, 10, 1931 ls tlock gtinst, and at leasthin iarththrouh, tlfie wilc'ie in 50 265,490 Germany Oct. 9, 1913 e we ormmg region, w ere y t e we is orme on said wire in said region under pressure forming conditions, OTHER REFERENCES and simultaneously directing a continuous, stable flow of Manufacture 0f Pulp and Paper, 3rd ed., v01. V, See. 1, a lesser portion of said fiowing stream of stock from Page 48 (1939), Published by McGraw-Hill, New Yorkthe outlet of said conduit, backwardly along the wire and (COPY in Division 67) away from the web-forming region, as said wire moves Modern Paper Making by CiaPPerton et ai PP- 161.

163, 166, published by Blackwell, Oxford. Eng. (1947). (Copy in Div. 67.)

into the web-forming region, whereby substantial pressure variations in the ow within said conduit at the web-

Claims (1)

1. IN A PAPERMAKING MACHINE OF THE PRESSURE FORMING TYPE, A SOURCE OF SUPPLY OF STOCK, MEANS FOR DELIVERING A FLOWING STREAM OF STOCK UNDER PRESSURE TO THE WEB-FORMING REGION OF SAID MACHINE, SAID STOCK DELIVERY MEANS INCLUDING MEANS WHICH DEFINES THE WALLS OF AN ENCLOSED FLOW CONDUIT AND SAID WEB-FORMING REGION BEING LOCATED AT THE DISCHARGE END OF SAID CONDUIT, A FORMING WIRE, AND MEANS FOR SUPPORTING SAID WIRE AND FOR MOVING SAID WIRE ACROSS THE DISCHARGE END OF SAID CONDUIT IN CLOSE PROXIMITY TO DEFINING WALLS THEREOF, WHEREBY THE WEB IS FORMED ON SAID WIRE IN SAID REGION UNDER PRESSURE FORMING CONDITIONS, SAID WALL DEFINING MEANS INCLUDING A SECTION WHICH IS SPACED FROM, AND IS SO POSITIONED RELATIVE TO, SAID WIRE AS SAID WIRE PASSES THROUGH SAID WEB-FORMING REGION AT THE DISCHARGE END OF SAID CONDUIT THAT THERE IS CONTINUOUS STABLE FLOW OF STOCK THROUGH THE DISCHARGE OUTLET OF SAID

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