US3373080A - Stock inlet for a papermaking machine - Google Patents

Description

D. w. APPEL ETAL 3,373,080

STOCK INLET FOR A PAPERMAKING MACHINE March 12, 1968 3 SheetsSheet 1 Filed April 8, 1965 O O O O O O O O March 12, 1968 D, w, APPEL ETAL 3,373,080

STOCK INLET FOR A PAPERMAKING MACHINE Filed April 8, 1965 3 Sheets-Sheet 2 March 12, 1968 D. w. APPEL ETAL 3,373,080

STOCK INLET FOR A PAPERMAKING MACHINE Filed April 8, 1965 s Sheets-Sheet 5 United States Patent Ofiice 3,373fi8d Patented Mar. 12, 1968 3,373,080 STOCK INLET FOR A PAPERMAKING MACHINE David W. Appel and John B. Graham, Neenah, Wis., and

Charles L. Sanford, Memphis, Tenn, assignors to Kimberly-Clark Corporation, Neenah, Wis., a corporation of Delaware Filed Apr. 8, 1965, Ser. No. 446,643 Claims. (Cl. 162-343) ABSTRACT OF THE DISCLOSURE A stock inlet for a papermaking machine including a stock redirecting section having an array of openings through it connected to the side of a stock header, a pair of parallel plates forming a thin stock turbulizing passage between them for directing stock onto a Fourdrinier fabric and a transition section formed with a passage therethrough which has the relatively large thickness at its entrance end of the array of openings and which has at its outlet end the relatively thin thickness of said passage for flowing the stock from said openings to said passage.

The invention relates to papermaking machines and more particularly to stock inlets for such machines. Still more particularly the invention relates to a stock inlet with a pair of parallel, long, fiat, closely spaced plates defining a long, thin slot between them through which paper stock may be ejected on to a Fourdrinier wire or forming fabric and which provides desirable small scale turbulence in the stock.

It is an object of the present invention to provide, particularly in connection with an inlet of this type, an improved flow spreader and stock guiding means for effectively directing paper stock between the pair of closely spaced, parallel plates. More particularly, it is an object of the invention to provide such a flow spreader that utilizes a plurality of parallel passages connected to a stock supply conduit for laterally directing and guiding the stock with respect to its flow in the conduit. It is contemplated that the passages shall be so widely spaced at their inlet ends as to prevent the stapling of fibers be tween the openings and shall be more closely spaced at their outlet ends so as to reduce the effect of wakes in the stock. It is also contemplated that the flow spreader shall include an intermediate portion having a passage therein with a relatively wide end for collecting the stock from these openings and gradually tapering to the close spacing of the parallel plates so that the intermediate portion cooperates with the thin slot in evening the flow of stock across the inlet.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the following description of a preferred form of the invention, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a fragmentary diagrammatic illustration of a papermaking machine utilizing the improved paper stock inlet of the invention;

FIG. 2 is a top view of the stock inlet;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is an end view of a certain part of the inlet taken from line 44 of FIG. 3;

FIG. 5 is a fragmentary sectional view, similar to FIG. 3, of a modified stock inlet embodying the principles of the invention;

FIG. 6 is a sectional view on an enlarged scale taken on line 66 of FIG. 5;

FIG. 7 is a view taken from line 7--7 of FIG. 6; and

FIG. 8 is a view similar to FIG. 7 of still another modified form of inlet;

Like characters of reference designate like parts in the several views.

Referring now to FIG. 1, the illustrated papermaking machine may be seen to comprise an endless forming fabric 10 which is movably disposed on a plurality of supporting rolls 11, 12, 13, 14-, 15, 16, 17, 18 and 19. The fabric 10 may for example be the usual Fourdrinier Wire made of interwoven metal wires or the fabric 10 may be made of interwoven synthetic filaments if desired. Such a fabric or wire, as is well known, has many interstices therethrough allowing Water drainage for the formation of a paper web from a supply of paper stock deposited on the fabric.

The roll 11 may be termed a slice roll; the roll 19 may be termed a breast roll and the roll 12 may be termed a couch roll. The rolls 13, 14, 17 and 18 are simple turning rolls; the roll 16 may be a conventional stretch roll for tightening or loosening the fabric 10 on its supporting rolls; and the roll 15 may be a conventional guide roll one end of which is fixed and the other movable for causing the fabric 10 to move about its supporting rolls in a certain predetermined path.

An endless top felt 2t) also extends about the slice roll 11 and is located between the fabric 10 and the roll 11. The felt 20 is movably supported by means of a plurality of additional rolls, including rolls 21, 22, 23 and 24. The rolls 21, 22, and 23 are simple turning rolls, and the roll 24 is disposed immediately above the couch roll 12 to have a nip with the latter roll. The felt 20 may be brought into contact with a suitable steam heated drier (not shown), and the felt 20 may be passed through presses (not shown) along with bottom felts not shown) for dewatering of the paper web, which is carried on the bottom side of felt 20 (as will be hereinafter described) for the purpose of providing a completed paper web on the drier. Such constructions are disclosed, for example, in a co-pending patent application of John B. Graham, Ser. No. 419,765, filed Dec. 21, 1964, and generally similar constructions are disclosed in a co-pending application of Charles A. Lee at. al., Ser. No. 161,058, filed Dec. 21, 1961.

It will be observed that roll 1? is located with its center above the center for the roll 11 and that there is a gap, which may be of less than an inch, provided between the rolls 11 and 19. The fabric 10 bridges the gap between the rolls 11 and 19 and travels for substantially around the roll 11. The felt 20 extends for a greater are around the roll 11, and together the fabric 11) and felt 20 extend from the roll 11 to the rolls 12 and 24.

A paper stock inlet 25 is provided for directing stock between the rolls 11 and 19 and on to the portion of the fabric 10 that bridges the gap between the rolls 11 and 19. The stock passes around the roll 11, in a sandwich between the fabric 10 and felt 28. The fabric 10, due to the tension in the fabric, exerts a substantial pressure on the roll 11; and, due particularly to this pressure, the stock in this sandwich is dewatered with white water passing outwardly through the interstices of the fabric 10 and forms a paper web. Centrifugal force is also effective in causing water to drain from the stock in this sandwich, and further drainage takes place as the wire-web-felt sandwich passes from the roll 11 to the rolls 12 and 24. The Wire 10 separates from the felt 20 in the nip between the rolls 12 and 24, and the paper web continues to travel on the lower surface of the felt 29 for further dewatering and drying by the presses and drier drum.

The inlet comprises a stock supply pipe or conduit 26 (see FIG. 2) having a relatively large diameter inlet portion 26a, a relatively small diameter outlet portion 26b and a tapered connecting portion 26c. In addition to the conduit 26, the inlet 25 comprises a stock discharge portion 27 and connecting intermediate parts 28 and 29.

The part 28 is a rigid member having a plurality of openings drilled therethrough which are disposed in vertical rows a and b (see FIG. 4). The conduit 26 is split along one side to have a side opening 260. in it, and the part 28 is screwed on to the conduit 26 so that the openings 30 are in communication with the opening 26d. Each of the rows a has three openings 30 in it, and each of the rows 12 has two openings 30 in it. In the particular embodiment illustrated, the openings 30 are inch indiameter; the rows a are spaced 1 /8 inches apart; and the rows b are spaced 1% inches apart. The openings 30 are also disposed in horizontal rows 0, d, e, f,

' and g which are spaced 1 inch apart in the particular embodiment illustrated. The diameters of the openings 30 and the spacing of the rows are such that there is at least a distance of /3 inch between edges of the openings 30. If the openings 30 had their edges in contact or overlapping, hang-up of paper fibers on the sharp edges from stock flowing into the openings 30 could be expected; and, therefore, the inch spacing has been provided. In this described embodiment, the openings 30 on the side of the intermediate part 28 opening into the conduit 26 provide a 42 percent open area in the intermediate part 28.

The openings 30 have a uniform diameter for much of their length; however, each of these openings is preferably flared outwardly to have a flared portion 30a at the side of the intermediate part 28 in contact with the intermediate part 29. It is preferable, for reasons to be hereinafter described, that the openings 30 do not flare greatly on their ends adjacent the portion 29, and a flaring of approximately 7 has been found satisfactory. In the particular embodiment illustrated, the openings 30 are of uniform diameter for about 4% inches of their length, and the flared portions 30a are about 2% inches long, so that the complete part 28 is-about 7 inches thick. As will be hereinafter more fully described, the openings 30 have flared ends 30a for the purpose of reducing the open area of the part 28 adjacent to the part 29 so that no appreciable wakes of the stock occur at these ends of the openings 30. The diameter of each of the openings 30 at this side of the part 28 is about 1 inch, and the flaring has the effect of reducing the minimum distances between openings to about inch. This side of the part 28 has about 68 percent open area in the particular embodiment described.

The intermediate part 29 is provided with a cavity 31 which has a wide portion 31a adjacent the part 28 and has a narrow portion 31b at the other end of the part 29. An intermediate cavity portion 310, which is formed by curved side walls and which narrows from the width of the portion 31a to that of the portion 31b, connects the portions 31a and 31b. In order that there shall be no rapid reductions in width of the cavity 31, it is desirable that the part 29 be about as thick as the part 28, such as 6 inches. The part 29 is formed by upper and lower casing portions 32 and 33 which are screwed to the part 28 and upper and lower internal parts 34 and 35 which form the cavity 31 between them. The parts 34 and 35 are fixed by means of screws with respect to the upper and lower casing portions 32 and 33.

The stock discharge portion 27 comprises upper and lower casings 36 and 37 and, in addition, flanged parts 38 and flat plates 39 and 40 which provide opposite, parallel, plane surfaces 41 and 42. The surfaces 41 and 42 form the boundaries of a thin passage 43 of about inch thickness, which is in alignment with the portion 31b of the cavity 31. Connecting parts 44 and 45 are provided between the plates 39 and 40, as illustrated; and lugs 46 hold the parts 44 and 45 in place. Screws 47 are provided for adjusting the plates 40 so that their inner surfaces are parallel for the complete width of the inlet. It will be observed that the plates 40 have relatively sharp edged terminal portions 40a, and the paper stock exits from the passage43 between these portions 40a into the gap between the rolls 11 and 19.

In operation, stock slurry is supplied to the conduit 26 at its large diameter end 26a, and the stock slurry flows into the openings 30 in the connecting part 28 from the conduit 26. A small portion of the stock slurry that is supplied to the'conduit 26 at its inlet end 26a is allowed to discharge from the end 26b of the conduit 26, so that there are no dead ends in the conduit 26 adjacent any of the openings 30 in the connecting part 28. Between 7 percent and 15 percent of the stock may be allowed to discharge through the conduit end portion 26b for this purpose.

The openings 30 function to uniformly change the original direction of stock iflow longitudinally of the conduit 26 to a direction at right angles, that is, in the direction of the openings 30. The stock flows through the openings 30 with a relatively low velocity; however, the pressure of the stock remains relatively high; and little turbulence of the stock exists in the openings 30 since they are relatively large diameter. In view of the fact that there is at least inch between each of the openings 30 at their entrance ends, due to the diameters and spacings of the openings 30; there is no stock hang-up or stapling between the openings. Kraft and sulfite fibers, which are relatively long fiber generally are of about inch in length; and hence, they cannot drape over any of the connecting parts between the openings 30 which are considerably wider. The relatively long, uniform diameter, portions of the openings 30, which in the illustrated embodiment are about 4% inches long, are provided so that the openings 30 have an appreciable effect in changing the flow of the stock to be at right angles to its direction of flow through the conduit 26; and, in addition, this relatively great opening length assures that the intermediate part 28 has considerable strength and rigidity.

The stock flows through the flared portions 300 of the openings 30 and into the cavity 31. In view of the fact that the flaring is preferably about 7, there is no substantial separation between the flaring walls ofopenings 30 and the stock, and hence no stock vortices are formed in the flared opening portions 30a. Also, no substantial stock wakes exist as the stock flows from the openings 30 into the cavity 31, particularly in view of the fact that the flared portions 30a of the openings '30 increase the open area of the end of the part 28 containing the flared opening portions 30a to 68 percent and decreases the separation between the openings 30 to about A: inch.

The stock, in flowing from the thick portion 31a to the thin portion 31b of the cavity 31, has its velocity substantially increased and its pressure lowered. The cavity 31, in so narrowing the thickness of the stock flow, tends to even the flow crosswise of the inlet (in the direction of the conduit 26), so that ubstantially the same velocity and pressures of the stock exist in the passage 43 from one side of the inlet to the other. In view of the fact that the connecting portion 29 is preferably about 6 inches thick, and since the cavity 31 has this same length, the decrease in thickness of the stock flow :from about 5 inches in the wide passage portion 31a to inch in the thin passage portion 31b, does not take place unduly abruptly, and there are thus substantially no zones of separation of the stock and the sides of the cavity 31, and hence no substantial vortices in the stock are formed in the cavity 31.

The stock, in flowing through the thin passage 43, is given a fine scale turbulence due to the frictional action on the stock of the closely spaced surfaces 41 and 42 0f the passage. This action of the thin passage results in a paper sheet being formed that has nearly the same strength in the cross-machine direction as in the machine direction, which is very desirable.

The above described stock inlet advantageously accommodates the high stock pressures desirable for the turbulent type of inlet in which stock is discharged from between two closely spaced, parallel plates for the high speed production of paper. The stock under high pressures is brought to the inlet from the side through the round conduit 26 which resists these high stresses by the hoop action of the conduit rather than across flat plates as are found in conventional inlets receiving stock from the end of the machine, for example. The inlet furthermore is compact, lightweight and imple in construction due to the fact that the stock is brought to the inlet from the side through the round conduit 26 while still being strong enough to withstand these pressures.

The improved flow spreader and stock guiding means of the invention, including the intermediate parts 28 and 29, assure that the stock flow is substantially uniform from one side of the paperrnaking machine to the other. Due to the relatively long length of the openings 34 the stock is effectively turned laterally from its original direction through the supply conduit '26, and, for this purpose, the openings 30 are preferably greater than eight times their diameter in length, and they thus assure that the flow of the stock is not angled across the inlet as might be experienced with simple perforated plates. The partial recirculation of the stock through the outlet end 2612 of the conduit 26, in addition, assures good distribution of stock flow into the openings 30. The openings 30 are relatively small in diameter at their entrance ends as compared to their out-let ends and therefore sharp narrow bridging portions between the openings 39 at their inlet ends do not exist on which stock fibers might staple. Also, there are no substantial wakes between jets of stock flowing out of the openings 30, since the openings 30 flare outwardly at their outlet ends. The cavity 31 in the intermediate part 29 has no sharp angles and gradually tapers from a relatively wide width to a very narrow slot with gradually converging walls, so that there are no zones of separation between the walls of the cavity and the stock flowing through the part 29, whereby large scale vortices that would produce stock disturbances and streaks in the resulting paper web are avoided. Also, the tapering cavity 31 acting in conjunction with the narrow passage 43 effectively uniforms the stock flow crosswise of the inlet for producing a uniform sheet. The structure of the invention thus provides a well designed and gradual transition of fluid conduits and passages from the supply pipe 26 to the discharge end of the passage 43 and obviates stock disturbances in the passage 43, due to an inadequate stock supply system for the passage 43, to which light basis weight areas in the sheet might be attributed.

The part 29 is preferably only about 5 inches or 6 inches in length (measured in the direction of flow through the cavity 31). The distributor part 28 is thus located closely ahead of the turbulent flow nozzle comprising the parts 38, 39 and 40 which provide the thin parallel walled passage 43; and no intermediate distributor rolls, rods or stilling sections providing alternate acceleration and deceleration of the flow need be provided. The openings 30 have such size and spacing to give negligible wakes, but yet they are practical to fabricate. The part 28 may be of stainless steel or bronze, for example, and may have the openings 30 provided either by casting the openings in the part 28 or drilling them into the part 28.

The part 28 acts as a structural tie between the upper and lower sides of the inlet. The conduit 26 is provided with the elongated opening 26a in its side; and the part 28, which has substantial structural strength even though perforated with the openings 39, prevents the opening 26d from widening. The casing portions 32, 33, 36 and 37 are subject to force due to the stock pressure between the parts 34, 35, 38, 39 and 40; and the part 23, being screwed to the casing portions 32 and 33, holds the portions 32 and 33 from separating. The structural rigidity of the intermediate part 28 is particularly important with high speed paper machines in which high stock pressures are utilized. It is also important in this connection to have a close structural connection between the stock entrance end of the slot 43 and the intermediate part 28, since these high pressures do exist.

The part 28 is also preferably quite thin, and the openings 36 are quite short, such as about 6 inches; and the close coupling of the conduit 26 and the slot 43 advantageously imposes a low head loss on the stock slurry flowing from the conduit 26 to the slot 43. The length of the openings 30 is primarily dictated by the structural strength desired in the distributor part 28 for tying the casing portions 33 and 37 with respect to the casing portions 32 and 36 and for tying the edges of the opening 26d togetherotherwise the holes 30 should be sufliciently long to fully turn the stock so that it flows longitudinally of the holes. In this connection, 6 diameters (that is 6 times the minimum diameter of each of the holes 30) is sufficient; and a length of about 5" for the holes 30 is substantially the minimum length that is desirable.

Certain dimensions of the various parts have been given above by way of example, and it will be understood that these dimensions may well be changed while yet securing the advantages of the invention. The lands on the upstream ends of the openings 30 (the distance between the holes on lines between centers) should be as small as possible without fiber stapling. A land width of has been found to be satisfactory, and A is also acceptable for the lands between the openings 30 at their upstream ends. The diameters of the openings 30 are determined primarily by the allowable width of lands on the outlet ends of the openings and by the economic feasibility of drilling or casting various diameter openings. A hole diameter of A." is optimum, and the openings may well vary from /2 to A in diameter. With smaller size openings 30, the number of openings would be increased and the number of horizontal and vertical rows of openings 39 (as the openings are shown in FIG. 4) would also be increased.

The lands between the holes 30 on their discharge ends should be as small as possible. A; inch lands between the openings 30 on lines between their centers is considered as large as desirable, and is more preferable. The maximum distance between any point on a land and the nearest opening 30 at the discharge ends of the openings should preferably be only /8 which would restrict the diameter of the openings 30 to one inch. Since the lands on the outlet ends of the openings 30 should preferably be not more than /8" in width and the lands on the inlet ends of the openings 30 should preferably be A to an enlargement of diameter for the length of the openings 30 must be provided. To get a minimum head loss and the least likelihood of scale or slime forming within the openings 30, a tapered section for the openings 30 is desirable. We have indicated a preferable flaring of the openings 30 to be 7", but this angle may well vary from 3 to 10.

Slots may be utilized in lieu of the openings 30 through the intermediate part 28, and such a slotted construction is illustrated in FIGS. 5, 6 and 7. The part 5% corresponding to the part 28 is provided with a plurality of slots 51 therethrough which are of rectangular cross section and which are defined by vanes or partitions 52 extending perpendicularly to the plates 39 and 40. The partitions are uniform in thickness for most of their lengths, for example 3" out of a total length of 5"; and the partitions on their outlet ends are beveled so as to provide outwardly flaring beveled slot portions 51a and 51b (see FIGS. 6 and 7). The vanes 52 thus have narrower slot separating lands 52a on their discharge ends than the lands 52b on their inlet ends. The discharge lands 52a may, for example, be 3 wide; and the inlet lands 52b may, for example, be wide.

The vanes 52 extend between upper and lower portions 50a and 50b of the part 50, and the vanes are preferably cast integral with the portions 50a and 59b. The portions 50:: and 50b are preferably beveled in the same manner as are the vanes 52 so as to provide outwardly flaring slot portions 510 and 51d on the upper and lower edges of the slots 51.

The lands 52a and the lands 52b may vary in width; however, the lands 52a are preferably to A3" in width and the lands 52b are preferably to Wide. The width of the slots 51 is preferably from /2" to l" and the length of the slots 51 is preferably from 6" to The height H of the slots 51 as they are Viewed in FIG. 7 is preferably 2 /2" to 5". The slots 51 effectively provide substantially the same action on the stock slurry as the holes 30 and may be easier to form than the holes 30.

FIG. 8 shows vanes 55 which may be substituted for the vanes 52 and which provide slots 56 between them. The vanes 55 are made from flat stock and in lieu of being formed integrally with upper and lower portions 57a and 57b, which correspond to portions 50a and 50b, the vanes 55 are welded to the latter portions by means of welds 58 and 59. The vanes of 55 have the same longitudinal sectional outline as the vanes 52 illustrated in FIG. 6 and provide outwardly flaring slot portions 56a and 56b corresponding to the flaring slot portions 51a and 51b. The vanes 55 may have inlet and discharge lands of the same width as those provided by the vanes 52.

Although we have, in particular, illustrated the round openings 30 and the slots 51 and 56 of rectangular cross section, it will be understood that openings of other shapes may instead be used, such as openings of hexagonal cross section (not shown). We wish it to be understood that the invention is not to be limited to the specific constructions and arrangements shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made Without departing from the principles of the invention.

What is claimed is:

1. An inlet for a papermaking machine comprising a paper stock conduit extending transversely of the inlet, a pair of closely spaced parallel surfaces extending longitudinally of the inlet and defining between them a thin stock discharge passagewith the ends of said surfaces defining an open end of the passage adapted to directly discharge the stock onto a moving Web forming fabric, and means providing a connection for flowing stock between said conduit and said passage, said last named means including a member having a plurality of spaced openings extending therethrough which lie at angles to said conduit and are directly in communication with said conduit and are arranged in an array having a substantially greater thickness than the thickness of said passage, said last named means also including an element providing a passage which receives stock from said openings and has an entrance end of substantially the same thickness as said array and which has an outlet end of substantially the same thickness as said first named passage to discharge stock into said first named passage and which gradually tapers in thickness from its entrance end to its outlet end.

2. An inlet for a papermaking machine as set forth in claim 1, said spaced openings each having a transverse dimension substantially greater than the thickness of said passage defined by said parallel surfaces.

3. An inlet for a papermaking machine as set forth in claim 1, said parallel surfaces and said passage defined by said surfaces being substantially longer than said spaced openings and also being substantially longer than said passage through said element.

4. An inlet for a papermaking machine as set forth in claim 1, said spaced openings being round in cross section and being arranged in rows.

5. An inlet for a papermaking machine as set forth in claim 1, said passage between said parallel surf-aces having a thickness of substantially inch.

References Cited UNITED STATES PATENTS 3,216,892 11/1965 Wahlstrom et al. l62-343 3,272,233 9/1966 Trufitt l62343 DONALL H. SYLVESTER, Primary Examiner.

A. C. HODGSON, Assistant Examiner.

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