US3220919A

US3220919A - Shaped rod turbulence generators for use in a flowing stream of paper pulp

Info

Publication number: US3220919A
Application number: US228621A
Authority: US
Inventors: Joseph D Parker; John F Schmaeng
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1962-10-05
Filing date: 1962-10-05
Publication date: 1965-11-30
Anticipated expiration: 1982-11-30
Also published as: GB1047952A

Description

D. PARKER ETAL SHAPED ROD TURBULENCE GENERATORS FOR USE IN A FLOWING STREAM OF PAPER PULP Nov. 30, 1965 7- Sheets-Sheet 1 Filed Oct. 5 1962 INVENTORS L/OSEPH D. PARKER BY JOHN E SCHMAE/VG a/A ATTORNEYS Nov. 30, 1965 J. D. PARKER ETAL 3,220,919

SHAPE ROD TURBULENCE GENERATORS FOR USE IN A FLOWING R PULP STREAM OF PAPE 7, Sheets-Sheet 2 Filed Oct. 5, 1962 LP /6a.

C I 2555 LL INVENTORS JOSEPH D. PARKER BY JOHN E SCHMAENG A TTORNEYS 3 1965 J. D. PARKER ETAL 3,220,919

SHAPED ROD TURBULENCE GENERATORS FOR USE IN A FLOWING STREAM OF PAPER PULP Filed 001;. 5, 1962 7. Sheets-Sheet 5 L-3OO W 314 pain-W, mi

doss u D. PARKER BY JOHN E SCHMAENG W 2 K /%0RNEYS Nov. 30, 1965 J D. PARKER ETAL 3,220,919

SHAPED ROD TURBULENCE GENERATORS FOR USE IN A FLOWING STREAM OF PAPER PULP '7 Sheets-Sheet 4 Filed Oct. 5, 1962 INVENTORS dosEPH D. PARKER W BY JOHN FSCHMAEA/G I l 2 g TZTTORNEYS 3,220,919 N A FLOWING Nov. 30, 1965 J. D. PARKER ETAL SHAPED ROD TURBULENCE GENERATORS FOR USE I STREAM OF PAPER PULP TSheets-Sheet 5 Filed Oct. 5, 1962 INVENTORS Nov. 30, 1965 J. D. PARKER ETAL 3,220,919

SHAPED ROD TURBULENCE GENERATORS FOR USE IN A FLOWING STREAM OF PAPER PULP fSheeias-Slxeet 6 Filed Oct. 5, 1962 S R m use m m? E W H O I 0 C T .5 T O A H fix E O S J @w W Nov. 30, 1965 J. D. PARKER ETA 3,220,919

SHAPED ROD TURBULENCE GENERATORS FOR E IN A FLOWING STREAM OF PAPER PULP Filed Oct. 5. 1962 7 Sheets-Sheet 7 Xf/i/ 'IL INVENTORS JOSEPH D. PAFPKEP BY JOHN EScHMAEA/G United States Patent Ofilice 3,220,919 Patented Nov. 30, 1965 SHAPED ROD TURBULENCE GENERATORS FOR USE IN A FLOWING STREAM OF PAPER PULP Joseph B. Parker and John F. Schmaeng, Beloit, Wis.,

assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Oct. 5, 1962, Ser. No. 228,621 3 Claims. (Cl. 162343) This invention relates to the handling of fiuid slurries, and more particularly, to the maintenance of desirable fiber dispersion in stock slurries for paper making and the like processes.

Prior attempts to establish uniform distribution of fibers in the stock slurry and to maintain fiber distribution, once established, along the flow path or stream in the headbox prior to deposition of the stock on the forming surface have involved employment of such complicated auxiliary equipment as perforated rotary rolls, commonly referred to as rectifier rolls, holey rolls, or silencing rolls, and other mechanical vibrating, shaking and stirring devices, all of which induce turbulent flow currents of large amplitude in the slurry.

A major disadvantage attendant use of such prior art devices resides in the tendency of the fibers to form clots, flocks, or agglomerations which, when deposited on the forming surface, result in undesirable localized irregularities of high density in the forming Web. In some instances, such clots and the like break down the web, thereby interrupting production.

By employment of the present invention, we eliminate the requirement for rotary, vibrating or other moving auxiliary means in the headbox and provide for delivery of the stock slurry to the forming surface of a paper making machine under conditions of substantially uniform mean velocity, minimum large scale flow turbulence, and minimum gross secondary fiow patterns wherein the fiber distribution and dispersion in the liquid vehicle are substantially uniform, thereby permitting formation on the forming surface of a web having substantially uniform density and fiber distribution throughout. The practice of the present invention also substantially reduces the formation of undesirable clots, flocks or agglomerations in the turbulent stock.

It is, therefore, an important object of the present invention to provide an improved method and apparatus for effecting the desired distribution of particulate material in a liquid vehicle, such as the fibers in paper making stock or slurry.

Another object of the instant invention is to provide an improved apparatus for distributing particulate material in a liquid vehicle, comprising a plurality of first means extending transverse to a liquid vehicle flow path for generating small scale turbulence in the liquid vehicle to distribute the particulate material therein, and a perforated member upstream from said first means converting the liquid vehicle under pressure into a plurality of high speed jets flowing through the perforations of the member in the direction of said first means.

Yet another object of the instant invention is to provide an improved method of distributing particulate material in a liquid vehicle, comprising generating a plurality of jets in a stream of such vehicle, generating successively smaller scale turbulence in the stream downstream from the jets to distribute the particulate material therein, and effecting controlled amplitude of the turbulence in the stream still further downstream to increase distribution of the particulate material therein.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is an elevational view with parts broken away and parts shown in section of a headbox for a paper machine embodying the instant invention;

FIGURE 2 is an essentially diagrammatic cross sectional top plan view of a headbox comparable to that shown in FIGURE 1 (but of smaller width), taken generally along the line IIII of FIGURE 1, and for the sake of simplicity not showing the exact dimensions of the embodiment of FIGURE 1;

FIGURE 3 is an elevational view comparable to the view of FIGURE 1 but showing another embodiment of the instant invention;

FIGURE 4 is another elevational view comparable to that of FIGURES 1 and 3 but showing still another embodiment of the instant invention;

FIGURE 5 is another elevational view comparable to FIGURES l, 3 and 4 but showing still another embodiment of the instant invention;

FIGURE 5A is a fragmentary detail view showing a modification of the embodiment of FIGURE 5;

FIGURE 6 is a detail sectional elevational view showing an essential part of another headbox embodying the instant invention;

FIGURE 7 is a plan view taken substantially along the line VlI-VII of FIGURE 6 with parts shown in section;

FIGURE 8 is still another elevational view comparable to that of FIGURES 1, 3, 4 and 5 showing a different embodiment of the instant invention;

FIGURE 9 is an enlarged fragmentary sectional elevation of the central portion of the slice approach shown in FIGURE 8;

FIGURE 10 is a view comparable to that shown in FIGURE 9, but showing a modified arrangement;

FIGURE 11 is a fragmentary detail sectional elevation of a single rod, with parts broken away and parts shown in section;

FIGURE 12 is an enlarged section of the rod shown in FIGURE 11 taken substantially along the line XIIXII; and

FIGURE 13 is an enlarged sectional view of a rod comparable to FIGURE 12, but showing a different cross sectional structure for the rod.

As shown on the drawings:

In FIGURE 1 there is indicated generally by the reference numeral 10 a paper machine hea-dbox having a generally triangular cross section defined by a generally horizontal bottom wall 11, a generally vertical back perforated wall or plate 12 receiving a stock stream under pressure indicated generally at 13 and a top wall 14 swingably mounted on the back wall 12 to define a slice 15 with the bottom wall 11. The top wall 14 is inclined downwardly (about 10 from horizontal) toward the slice 15, so that the top wall 14 and the bottom wall 11 define a headbox chamber A that is tapered toward the slice 15. The chamber A is a tapered approach to the slice opening 15 for flowing a stock stream (filling such tapered approach A) in a generally (average) rectilinear direction D which may be assumed to lie in a plane bisecting the approximate angle C of 10 between the top wall 14 and bottom wall 11.

The chamber A contains a transversely extending, first multiplicity or bank of transversely (i.e., cross-streamwise) spaced abutments or rods 16 (e.g., 16a, 16b, 16c, 16d in FIGURE 2) each extending substantially completely across (transversely depth-wise) the stock stream, which are mounted for swingable movement with the top wall 14 (being secured at the top of the rods 16, by suitable bolts or the like, not shown). It will be seen from FIGURE 2 that these rods 16 are positioned in generally at 17 in FIGURE 1 are secured in like manner to the top wall 14 for swingable movement therewith and these second abutments or rods 17 (Le, 17a, 17b, etc.,

in FIGURE 2) are positioned completely across the stock stream downstream from the first bank of rods 16, but upstream from the slice 15. The first bank generates substantially uniform small scale turbulence of a first order of magnitude, whereas the second bank 17 is positioned in the turbulence wakes of the first bank 17 to minimize collection of fibers, etc., on the faces of the rods 17, which generate substantially uniform smaller scale turbulence of a second order'of magnitude.

Additional and similar, successive, downstream banks of

rods

18, 19, 20 and 21 are shown in FIGURE 1 with the down-stream-most bank of rods 21 still being spaced from the slice 15, and the rods in the succession of banks 16 through 21 are generally formed of successively smaller diameters with successively smaller transverse spacing therebetween. It will be noted that only the first three

banks

16, 17 and 18 are represented in FIGURE 2, again for purposes of simplifying the disclosure of the function of these banks of rods which will be discussed in detail hereinafter. "As is indicated generally in FIGURE 1, the stock is pumped from a fan pump or suitable device P for generating a stream of stock under pressure through a main cross stream header indicated at 30, from which the stock under pressure rises through a plurality or relatively long narrow generally parallel risers 31, which also extend across the full width of the machine. These risers 31 feed into the bottom of an inlet compartment 32 in which the stock from the various risers 31 is merged into a main stock stream 13 flowing at a comparatively slow flow rate under substantial pressure and this main stock stream flows against the perforate plate 12 where at the stream is converted to lower pressure, high speed jets flowing out of the perforations. As indicated in FIGURE 2, the perforations in the plate 12 include rows extending in the cross machine direction, such as the

row

12a, 12b, 12c, 12d (only 12d of which being shown in FIGURE 1), and as shown in FIGURE 1, the perforations in the plate or back wall 12 extend also in generally vertical columns, such'as the perforations 12d1, 12d and 12d2. Immediately at the off-running side of each column, such as the

column

12d,1 12a and 1202 there is positioned a rod 16d from the first bank 16 of rods, so that a jet of stock from each of these perforations will impinge upon the rod or abutment 16d and will immediately undergo an abrupt change in direction (thereby keeping the operating face 16d1 clean).

The chamber 32 and approach A are operated full of stock. It will thus be seen that the stock flows through the submerged perforations in the back plate 12 and through the entire slice approach A under pressure and out the slice onto a forming wire W of the conventional Fourdrinier type traveling around a breast roll 33 in conventional fashion.

A plurality of pedestals indicated at 34 secured to a fixed support such as the floor F carry a cross frame 35 having a plurality of

uprights

35a, 35b, 35c and 35d. A floor or bottom wall portion 11a of the overall bottom wall 11 is secured to the top of the

uprights

35b, 35c 35d by suitable means such as the welds indicated, for fixed. mounting of the generally. horizontal floor portion 11a. The back wall 12 is, likewise, fixed and rigidly mounted to the back of the floor wall 11 and the rear upright 35d by suitable means such as welds or the like.

The headbox 10 is, of course, provided with side walls only the rear one of which 36 is indicated at the back of the headbox chamber A in FIGURE 1, but in FIG- URE 2 the other wall 37 is also indicated. The

side walls

36 and 37 have side frames secured thereto, only one of which is indicated in FIGURE 1 generally at 38. The side frames 38 carry pivots one of which is indicated at 39 which swingably mount an upright frame portion 14a of the top wall 14 (about the pivot 39, and about the rear wall 12 which is, of course, rigid with the side frame 38. A conventional roof lift device 40 carried on the side frames 38 and operating a lift cable 41 connected via a pivot 42 to the side frame 14a of the top wall 14 is used to swing the top wall 14 from the position indicated in FIGURE 1 to the phantom position also shown in FIGURE 1 wherein the top wall is indicated in the primed numbers. It will be appreciated that the banks of rods indicated by the primed reference numerals 16 through 21 are likewise moved with the top wall 14 into the phantom position shown in FIGURE 1 when it is desired to open up the headbox 10 for maintenance, cleanup, or other sutdown operation.

In this respect, it will be noted that the downstreammost banks of

rods

20 and 21 are anchored to an apron ing a part of the support frame 35, so that the apron piece 50 may define the forward or off-running continuation 11b of the floor wall 11a.

There is a slight space 53 between the floor w-all' sections 11a and 11b which feeds into a chamber defined by a base plate 35 for the cross frame 35, the two

uprights

35a and 35b and the forward portion of the wall portion 11a. These elements form a cross chamber B which is used to help purge the headbox chamber A of any dirt or particulate material which might tend to lie along the bottom thereof. This purge chamber B is functional during operation of the machine and a swingable damper 54 pivoted to the bottom of the floor wall 11a and adjustable in position by a set screw assembly 56 of conventional structure. It will be appreciated that this floor slot 53 with stock flow control means in the form of the damper element 54, will permit a very slow flow purging of heavy materials from the stock during operation, or it will permit a fast flow recirculation of stock :beneath the floor 11 at this position and back by conventional means to the stock system.

The side frame 14a for the top wall 14 has an upper extension 1412, which carries the cable pin 42 with attached cable 41 (whichelements are mounted at both sides of the machine) and it also carries at its forward end a cross bar or pivot 60. Bell crank arms 61 pivotally connected at 62 to a slice adjusting jack or hydraulic motor 63 pivotally connected at 64 to the frame 14b are used for delicate slice control of a forward slice plate 65 that is secured to and pivotal about a rotatable bar 66. A plurality of conventional adjusting screws 67, are operatively connected to the forward end of the slice plate 65 and a pivot bar 68 in the bell crank 61. The slice adjusting jacks 63 will thus provide for maximum adjustment of the position of the slice plate 65 and the adjustable screws 67 provide for delicate adjustment thereof.

The cross bar 60 also pivotally mounts a frame element 70 presenting an arcuate face 70a for sliding engagement with a contiguous arcuate portion 14c at the forward end of the top wall 14, so that sliding movement of the arcuate face portion 70a may move the cross bar 66 to a limited extent toward and away from the slice 15. The limited movement of the cross bar 66 of course results in limited movement of the slice plate 65; and movement of the arcuate element 70a is effected by a second hydraulic motor 72 pivotally connected to the frame 70 at 73 and pivotally connected to the top wall side frame 14!) at 74. The slice adjustment elements indicated by the 60 and 70 series of reference numerals are all carried on the cross bar 60 which in turn is carried with the top wall 14 during swinging movement thereof.

Referring in greater detail to the rod banks 16 through 21 within the headbox chamber A, it will be seen that the rod banks 16 through 19 are not secured to the fixed floor portion 11a and instead terminate immediately adjacent thereto with slightly rounded ends. The rod banks 16 through 19 are also not in exact vertical alignment, instead being tilted about off vertical (i.e., at an angle X of about 95 to the stream direction D) in the direction of stock flow. The rounded ends plus the angle of tilt for the rod banks 16 through 19 afford unusual advantages in self-cleaning of these devices during operation. In fact it has now been found that the upstream or operating faces of rods (such as the rods 16 through 19) extending at a downstream slant from one wall 14 to closely spaced relation from the opposite wall 11 preferably are positioned to define an obtuse angle with respect to the planes of both

walls

11 and 14, and more specifically, an obtuse angle X of about 95 to 135 with the general flow direction D.

Referring specifically to FIGURE 2, it will be seen that each of the rods, such as the rod 16d has a generally circular cross section which is preferred, although it will be appreciated that the invention also contemplates the use of rods having other cross sectional shapes such as that of a polygon (e.g., triangular, rectangular, etc.), and the invention also contemplates the use of turbulence generators other than banks of rods, which include grids, slotted plates or the like, but in each case there should be certain fundamental open areas and other structural characteristics. For example, it is important that the structure used employ a substantial multiplicity of abutments, rods or other structures presenting turbulence generating land areas (e.g., such as the upstream face 16a1 of the rod 16d) between open areas A-1 and A-2 accommodating stock flow for generating a first substantially uniform pattern of small scale turbulence of a first order of magnitude in the stock stream. For this purpose, it will be noted that the rod 16d has the preferred generally rounded upstream side or face 16d1 and that it also terminates abruptly at the downstream side 16d2, such abrupt termination being contrasted to an elongated teardrop shape which would result in streamline flow past the rod 16a. The abrupt termination at the downstream face 16d2 results in turbulence generation diagrammatically indicated in the upper portion of FIGURE 2 as being characterized by a low pressure area LP at the immediate downstream side of the rod 16a, and wakes W, W trailing along the side edges of the rod 16a at the off-running side. Since the stock stream in this region is not exposed to air at the surface, the creation of such turbulence even at high operating speeds does not tend to draw air into the stock. It will be noted that each of the rods in the first bank 16 has a comparatively large diameter D4, which for practical purposes may range from about A of an inch to about 1 /2 inches, but which is about 1% inches in the embodiment shown in FIGURE 2. The perforations 12a through 12d in the plate 12 preferably have a diameter that is within the range from about /2 of the diameter D-l to about equal to such diameter D-1, and in the preferred embodiment here shown the diameter of the perforations 12a, etc., is about 1 nch. This produces a submerged jet which serves to effectively clean the operating or upstream face of each of the rods in the banks 16.

The center-to-center dimension M-l between ad acent rods 16b and 160 in the first bank 16 is preferably equal to about twice the diameter D1, which would give a total open area in the rod bank 16 of approximately 50%. The open area in the rod bank 16 may, however, range from a practical minimum of about 25% to a practical maximum of about 75%, so that the ratio of M-l to D-1 may range from about 3 to 1 to 1 to 3.

It will also be noted that the first bank of rods 16 is spaced upstream from the second bank of rods 17 a distance L-l (from center-to-center between the rod banks 16 and 17). The second rod bank 17 is located so as to receive the turbulence generated by the first rod bank 16 in partial decay. The distance L-1 is approximately equal to about 2 to about 5 times the center-to-center spacing M-l in the first rod bank 16, since it is found that maximum intensity of the flow turbulence appears to occur from about 2 to about 4 times the distance M-1 downstream of the rod bank 16, depending upon the overall average velocity of the stock stream, which is another factor that must be considered in selecting the preferred distance L1. At distances from the first bank 16 greater than those just indicated for the distance L-l, the turbulent flow generated in the stock by the rods 16 tends to dissipate or decay and to merge into a substantially uniform means flow pattern. Thus the second bank 17 is located a distance L-1 downstream from the first bank 16, such distance L-l being greater than the distance of the zone of maximum intensity of the first order of flow turbulence created in the slurry by the first bank of rods 16 but less than the distance from the first bank of rods 16 to a region where uniform mean flow occurs.

It will further be noted from FIGURE 2 that the spacings L-l, L-2, etc. between the

rod banks

16, 17, 18, and the space between the first bank 16 and the perforated plate 12, each afford a region of abruptly increased crosssectional area intermediate each such turbulence generating cross-machine extending

surface elements

16, 17, 18, etc., which in turn provides a region (e.g., of preferably 50% open area) of abruptly decreased cross-sectional area in the stock stream, whereby the stock in the stream is subjected to a primary relatively gradual velocity increase via the converging or tapered alignment of the top and bottom walls 14 and 11 (FIGURE 1) plus superimposition of a succession of sequentially decreasing turbulence-generating zones (such as the zones or sequences S S S S of FIGURE 2) which involve abrupt cross sectional area diminuition followed by abrupt increase to superimpose secondary cyclic stock velocity acceleration followed by deceleration at each such sequence S 3: S2: 1-

The rods 17 of the second bank are substantially smaller in diameter D-2 and the center-to-center spacing M-2 is also substantially smaller, sothat each of the rods 17 such as the rod 17x presents a turbulence generating land area 17x1 that is substantially smaller in size than the turbulence generating land area 16d1 of the first bank 16 and that is positioned between smaller open areas such as A-3 accommodating stock flow through the rod bank 17, for generating a second substantially uniform pattern of smaller scale turbulence in the stream, and of turbulence of a second order of magnitude in the stream. The second bank 17 thus receives the initially induced first order eddy currents in a state of partial decay from the first bank 16 and converts the same into a substantially greater number of second order eddy currents which are lesser in magnitude than the first order eddy currents; and such second order eddy currents tend to further disperse and distribute the fibers throughout the stock while the amplitude of the second order eddy currents is reduced relative to the amplitude of the first order eddy currents. The upstream face portions of the rods 17 (such as the face portion 17x1) are kept clean by virtue of the fact that they are exposed to the trailing wakes from the first rod bank 16. Such turbulence against the operating faces of the rods 17 tends to reduce or minimize stapling or the collecting of fibrous elements on the upstream surfaces of the rods 17.

The third bank of rods 18, shown in FIGURE 2, is composed of rods of still smaller diameter D-3 in a bank having still smaller center-to-center spacing M-3 between the rods 18, which are again transversely spaced between the

side walls

36 and 37 extending completely across between the

side walls

36 and 37. The rod bank 18 is also positioned so as to be positioned in the wakes generated by the rod bank 17 while still in a condition of partial decay, and the rod bank 18 is spaced downstream from the rod bank 17 a distance L-2 which is preferably within the range of about 2 to about 5 times the center-to-center spacing M 2 in the rod bank 17.

Another aspect of the instant invention involves spacing the downstream-most rod bank from the slice opening a distance within the range of about 3 to about 7 times the center-to-center spacing between the rods or'abutments in the downstream-most rod bank. Thus, if the embodiment of the invention shown in FIGURE 2 is assumed to employ the rod bank 18 as the downstreamrn-ost rod bank in a headbox having a slice opening S-l indicated diagrammatically by a dotted line, when the rod'bank 18 should be spaced upstream from the slice opening S 1 a distance L-3 which should be within the range of about 3 to about 7 times the center-to-center spacing M-3 in the rod bank 18. In like manner, referring to FIGURE 1, it will be appreciated that the downstream-most rod bank 21 should be spaced from the actual slice opening 15 a distance that is within the range from about 3 to about 7 times the center-to-center spacing between the rods in'the rodbank 21.

It will thus be seen that in a final quieting zone X (FIGURE 2) of partial turbulence decay and of a longitudinal or downstream-wise dimension X of at least a plurality of the longitudinal dimensions of the immediate upstream sequence S is provided between planar smooth convergingly tapered walls. Although it will be understood that even the plain walls of the quieting Zone X have some (nominal) shear-effect turbulence generation upon the stock stream flowing past this zone X the zone X essentially provides for partial decay of turbulence generated and secondary velocity change eifects generated in the turbulence-generating

rod banks

18, 17, 16.

Another important aspect in the instant invention resides in thediscovery that although the turbulence generating land areas (i.e., the rod diameters here shown) in successive downstream rod banks should be reduced successively in size for successive generation of smaller and smaller scale turbulence, there is a practical minimum diameter for the downstream-most rods or abutments using a given type of paper making stock. Thus this minimum diameter may be smaller for extremely short fiber stock, but for most stocks the practical minimum diameter is about to /2 inch. Downstream-most rods of approximately this size turbulence generating land areas have been found to carry out the desired function of the headbox with minimum practical collection of fibers or stapling of strings that may have formed elsewhere in the stock system. In view of this, it will be appreciated that the intermediate rod banks, such as the rod banks 17 shown in FIGURE 2, will have rods of diameters D-2 significantly larger than the downstream-most rods 18 and significantly smaller than the diameters D-1 of the upstream-most rods 16. In the overall arrangement of FIGURE 1, this is also true, so that the rods in the banks -17, 18, 19 and 20 and successively smaller diameters, with the diameters of the rods in the bank 20 being larger than those in the bank 21, and the rods in the bank 21 having the minimum practical operating diameter previously described.

With respect to the open areas in the various rod banks, 'in general practice an open area of approximately 50% 8 in each of the successive rod banks is preferred, although the open areas in the rod banks may be within the previously recited range of about 25% to about Referring now specifically to FIGURES 3, 4 and 5, it will be seen that parts shown therein corresponding in function and/ or structure to parts previously described in FIGURE 1 are designated by the same reference numeral in the 300 series in FIGURE 3, in the 400 series in FIG- URE 4 and in the 500 series in FIGURE 5.

In FIGURE 3 the tapered approach A300 to the slice 315 contains the successive turbulence generating rods 316 through 321, generally conforming to the sizes, spacing and structure previously described, except that in FIGURE 3 the'rods are all substantially vertical and are secured to both the top and

bottom walls

314 and 311 for greater structural strength. The same is true of FIGURES 4 and 5, although the overall alignment of the tapered approaches A400, A400 and A500 is different to accommodate different machine structures and the use of different stocks.

The

headboxes

310, 410 and 510 are also diiferent from the headbox 10 of FIGURE 1, in that they are operated with the maintenance of a stock level L-300, L-400 and L-500 in each that is subjected to controlled air under pressure in a conventional pressurized headbox structure, with a conventional level control, as the level control pipe LC shown in FIGURES 3, 4 and 5, for control of the levels L300, L-400 and L-500 in accordance with the structure and arrangement shown in greater detail in US. Patent No. 2,509,822. Conventional sight glasses 301, 401 and 501 are employed for the convenience of the operators. 1

One essential difference between the headboxes of FIGURES 3, 4 and 5 and that of FIGURE 1, is that the perforated plate 12 in FIGURE 1 is arranged so as to impinge jets directly upon the first bank of rods 16, whereas different structures are used in the

headboxes

310, 410 and 510. Referring specifically to FIGURE 3, it will be seen that stock from a suitable source is fed into a tapered header aligned in cross machine direction and designated only in FIGURE 3 only by the large diameter inlet 302 and the comparatively smaller diameter outlet 303 of the tapered header, which feeds the stock in a cross machine direction with respect to a generally horizonally, transversely aligned perforated plate 312. The pressure in the incoming stream of stock forces the stock to change direction abruptly and converts the stock stream into a plurality of generally closely spaced high speed submerged jets impinging upon a first bank of transversely spaced rods 304 in generally parallel alignment with the plate 312. The impingement of the submerged jets upon the rods 304 (which have the relationship and diameter, spacing, etc., relative to the perforations 312av through 312e already described in connection with the

structures

12 and 16 of FIGURE 1), results in dispersion of the fibrous particles in stock and the creation of substantial small scale turbulence in the stock at the off-running side of the rod bank 304. The stock then is forced (under the pressurized head in the headbox 310) through a right angle turn and into the tapered approach A-300 while the stock still is in a condition of decaying turbulence. The advantage of the use of the headboxes 310, 410'and 510 is that entrained or trapped air in the stock being fed into the headboxes has an opportunity to escape into the pressurized air zone above the levels in each just prior to entrance into the tapered approaches in each of such headboxes.

InFTGURE 4, the stock is again fed in cross machine direction into the bottom of the headbox 410 at 402, from which the stock stream is converted into a plurality of high speed submerged jets passing through the perforated plate 412. In the headbox 410, it will be seen that the perforated plate is more closely spaced to the first bank of rods 416 in the-tapered approach A400, so the use of a bank of rods comparable to the bank of rods 304 shown in FIGURE 3 may be optional (with certain more easily dispersed stocks) for purposes of obtaining adequate dispersion of the fibers prior to entrance into the tapered approach A-400.

In FIGURE 5, the stock is again fed into the bottom of the headbox in cross machine direction through an inlet 502, and then converted to a plurality of high speed submerged jets passingthrough the perforations in the plate 512. The high speed jets passing through the perforations of the plate 512 impinge upon a headbox wall or bafiie 550, which results in an abrupt right angle turn in the stock fiow and the further dispersion of the fibers in the stock. The stock then flows in a relatively high degree of small scale turbulence upwardly, then through another right angle turn and into the tapered approach A500. As indicated in FIGURE 5A, however, at certain operating speeds and using certain stocks, it may be advisable to modify the structure of the headbox of FIGURE 5 to the extent of including a perforated plate 512A at the mouth of the tapered approach, so that it may function to impinge closely spaced high speed submerged jets against the upstream-most bank of rods 516 in the tapered approach A-500, much in the manner described in connection with the cooperating function between the perforated plate 12 in the first bank of rods 16 in FIGURE 1.

Another feature of the arrangement of FIGURE 5A involves the simplified mounting for the rod bank 516T. As indicated, the rod bank 516' is composed of a plurality of generally cylindrical hollow rods integral with an upper base plate 516A and a lower base plate 516B extending the full width of the approach A500'. The plates 516A and 5168 present generally rounded smooth surfaces to the flow stock within the inlet, and are seated in transversely extending grooves 514A and 511B in the top and bottom walls 514' and 511, respectively, so that the assembly of the rod bank 516' may be slid through transverse motion in and out of position in the inlet. The rod bank 516 is retained in position in the inlet A500 during operation by means of through bolts such as the bolts B516 extending through the top wall 514', the first rod shown of the bank 516, and the bottom wall or floor 511' to receive a nut N-516 on the threaded lower end of the bolt B-516 for securing the rod bank 516' in position. The rod bank 517 is mounted in like fashion (although the specific features of the bolt arrangement are omitted for the purposes of simplifying the disclosure). The hollow rod and bolt arrangement thus described in connection with FIGURE SA has a number of advantages, in that it provides for added structural strength for the inlet A-500' (which is operated under substantial pressure), while also providing for ease of assembly and disassembly in the manner indicated. This particular type of mounting affords distinct advantages in the case of the larger upstream rods in the practice of the invention, since these rods have rather substantial turbulence generating .areas of such width that they do not ordinarily tend to collect fibers or strings (particularly when the submerged jets of stock are impinged upon the operating faces). In the case of somewhat smaller rods, however, there have been found distinct advantages in using the tilted rod arrangement, one embodiment of which having been described in connection with certain of the rod banks of FIGURE 1 and another, and the most preferred embodiment which will be described in connection with FIGURE 8.

Referring now to FIGURES 6 and 7, it will be appreciated that the arrangement shown therein is a modification of the perforated plate and immediately adjacent bank of abutments (312 and 304) already described in connection with FIGURE 3. In FIGURE 7 it will be seen that the bank of transversely extending rods 604a through 604e, alphabetically, extends across the upwardly flowing stock stream (although not necessarily from wall to wall completely in this arrangement for the reason 1% that subsequent banks of abutments are contemplated as indicated in the tapered approach A-300 of FIGURE 3). The perforated plate 612 contains rows of

perforations

612a, 612b, 6120, 612d and 612:: which are spaced to extend transversely of the stock stream in one direction and each of such rows has a plurality of spaced holes extending transversely of the stock stream in general alignment with the transversely extending rods, as at the perforations 612e1, 612122, 612e3 and 612e4 which are mounted to impinge submerged jets of stock against the rod 604e. The diameter of the perforations 612a etc. is equal to or slightly less than the diameter of the rod 604, etc., as previously described. Although the rods of the 604 series are of rather substantial diameter, i.e., about one inch, so that they do not have a tendency to collect fibers or strings on the operating faces thereof at reasonably rapid stock flow velocities, the impingement of the submerged jets from the perforations of the plate 612 has the net effect of substantially eliminating any collection of fibers or strings on the operating faces of these rods, while simultaneously creating a particularly satisfactory dispersion of the fibers in the stock through the impingement effect. This thus creates an initial dispersion of satisfactory character, plus off-running turbulence from the rod bank 604 that is small scale turbulence, but which is reduced to still smaller scale turbulence by passage past the successive banks of successively smaller rods having successively smaller stock flow spaces therebetween, with each successive downstream rod bank receiving turbulent flow from the immediate upstream rod bank that has not completely decayed into uniform flow, so that such turbulent flow may serve to assist in minimizing the collection of fibers or strings on the operating faces of the rods in each of the successive downstream banks. In this way the final downstream bank or banks may comprise comparatively smaller rods of diameters as little as /8 of an inch to /2 of an inch, so that such downstream-most banks may impart the desired very fine scale turbulence to the stock at their off-running sides while still having the upstream turbulence impinging thereon of sufficient turbulent character to minimize collection of fibers and strings on such comparatively small diameter rods.

Referring now to FIGURE 8 it will be seen that still another embodiment of the instant invention is shown wherein elements of substantially the same type and function as those previously described are designated by the same reference numerals in the 800 series. It will be appreciated, however, that the embodiment of FIGURE 8 shows what is currently believed to be the superior embodiment of the invention in a number of respects. It will be appreciated that the previously described embodiments of the invention have utility with respect to one particular type of stock or another and often with respect to a plurality of different types of stock, but the embodiment of FIGURE 8 has been found to be superior to the previously described embodiments, at least with respect to certain commercial paper making stocks, for the reasons which will be described in detail hereinafter.

In general, the headbox 810 is provided with a perforated transversely extending plate 812 receiving stock under pressure (for example as shown in the embodiment of FIGURE 1), and

successive rod banks

816, 817, 818, 819, 820 and 821 again having the general overall transverse spacing, successively diminishing transverse spacing, successively diminishing rod sizes or abutment generating area sizes, successive spacing between the rod banks, etc. shown in the corresponding rod bank series in FIG- URE 1. With respect to the open areas in the various rod banks in FIGURE 8, the preferred open area is approximately 50% in each of the successive rod banks 816 through 821, although open areas in the rod banks may vary within the previously recited range of about 25% to about 75%. As in the case of the previously described perforated plates 12, etc., the perforated plate 812 has a generally smaller open area (for submerged jet generation) that is at least about /2 of the open area of the upstream-most rod bank 816 and is preferably within the range of about 5% to 15% open area (with the best results apparently being obtained using about to 12% open area.

As shown in FIGURE 8 the tapered approach A-800 is defined generally by a horizontal floor 811 and a top wall 814 inclined about 10 from the horizontal, so that the overall angle C8 between the top and

bottom walls

814, 811 is about 10. In practice, the angle of the tapered approach may vary from a minimum effective angle of about 5 to a maximum effective angle of about 25". In any case, the approximate average flow direction of the stock D-8 is presumed to bisect the angle C8 for purposes of simplification and reference to the angle of tilt of the rods in the banks 818 through 821.

In essence, the

rods

816 and 817 in the upstream-most two banks are mounted in substantially the manner described in connection with FIGURE 5A for the convenience of assembly and disassembly and the added structural strength advantages already described. The perforated plate 812 is preferably mounted in relatively closely spaced relation to the first rod bank 816 so as to effect the desired impingement of the submerged jets upon the rods in the bank 816, at a distance S of preferably about one to two times the perforation diameters in the plate 812,- although the operating range for the distance S may include as little as about /2 of the perforation diameters and as much as about four times the perforation diameters, in the preferred arrangement such as that shown in FIG- URE 8 wherein the submerged jets are actually aimed at the turbulence generating faces of the rods in the bank 816.

It will also be noted that preferably in the case of the smaller size rods 818 through 821 in the downstream banks it is particularly advantageous that the rods extend at a downstream slant or tilt from one wall (here the top wall 814) to closely spaced relation from the opposite wall (here the fioor wall 811) and provide in each case a slanted or tilted upstream face 818a through 821a. The slanted faces 818a, etc., preferably form an obtuse angle X-8 with the average flow direction line D-8 and (of course, also form a slightly larger'obtuse angle X-8a with the headbox wall 814 on which the rod bank 818 is mounted). Although the minimum dimension for the angle X8 may be as little as about 95, as indicated in FIGURE 1, it has been found that distinctly superior results are obtained if the angle X-8 is substantially greater and the angle X-8 may be as great as 135. Also, this angle may advantageously be increased slightly in successive downstream rod banks. As indicated in the embodiment 811), the rod bank 818 comprises a plurality of transversely spaced rods secured to a suitably formed transversely extending base plate 818A which may be fit in a recess 81413 in the top wall 814 for ease of assembly and disassembly and it is secured thereto by a plurality of bolts one of which is indicated generally at B818. The

rod banks

819, 820 and 821 are mounted in similar fashion.

Referring now to FIGURE 9 for a more detailed analysis of the arrangement of the

rod banks

819, 820 and 821, it will be seen that the rods in each of these banks terminate with rounded ends closely spaced from the floor 811 a distance T of about inch, so that any strings or fiber flocks which may have been formed upstream and not broken up or redistributed will not be able to collect on the turbulence generating front faces 819a, 820a, 821a. Instead, there will be no added accumulation of fiber on the slanted turbulence generating faces and whatever strings or other undesirable elements that may have reached the rod banks 819 through 821 will not be stapled on to the rods in this location for collection of additional fibers and will instead slip down and off the rounded ends through the small spaces T so as to cause minimum imperfections in the ultimately formed paper web. For this purpose, the obtuse angle of slantX-9 for the turbulence generating face 819a in each of the rods of the rod bank 819 is preferably about (and it may preferably range from about 110 to The obtuse angle X40 for the next downstream bank 820 is preferably about the same, whereas the obtuse angle X-11 for the downstream-most bank 821 is preferably a still larger obtuse angle of about 120. The angle X-11 has been found to be preferably about 5 to 15 greater than the angle X-9 or X-lti; and the angle X-11 is preferably within the range of about 110 to about 130. As previously indicated the line D-8 bisecting the angle C8 of about 10 is used for reference purposes.

It will also be noted that the floor 811 in FIGURE 9 is provided with grooves 811E and 811F which are filled with cross bars 809E and 809E", respectively, so as to provide a smooth floor for engagement with the stock stream. As indicated in FIGURE 10, however, the cross bar 809E is replaceable with the base plate 820a for the rod bank 820, so that the rod bank 820 may be mounted from the floor wall 811 rather than the top wall 814 in the manner shown in FIGURE 10, and the top wall groove 814E may be filled with the blank or cross bar 809E so that the top wall will present a smooth continuous surface to the stock stream. The cross bar 8MP may obviously be used for the same purpose with respect to the rod bank 819. It will be appreciated that in the arrangement shown in FIGURE 10, the turbulence generating upstream faces 820a for the rod bank 820 define an obtuse angle X-12 of approximately 110 with the center fi'ow line D-8, so that the turbulence generating faces 820a are thus slanted downstream at approximately the same obtuse angle X-12 as the obtuse angle X-10 indicated in FIGURE 9. The advantage of the arrangement shown in FIGURE 10 is that any possible channelling of flow along a wall face and/ or loss in turbulence generation and/ or rectification effected by the small spaces T between the rounded ends of the rods and the opposite wall face would be erased by having

alternate rod banks

819 and 821 extending from opposite wall faces as indicated in FIGURE 10. Other advantages from the arrangement of FIGURE 10 will be apparent with respect to the desirability of obtaining uniformity in turbulence generation throughout the stock stream while at the same time obtaining the desired advantages of employing rod banks or abutments wherein the elements extend only from one of the tapering

walls

811 or 814 to closely spaced relation from the other wall.

Still another particularly important aspect of the instant invention resides in the discovery of a unique configuration for a turbulence generating surface or face for a rod or similar abutment which further assists in avoiding the possibility of having fiber or strings or the like stapled or entrapped by the rod. This embodiment of the invention is shown in detail in connection wth FIGURES ll, 12 and 13. FIGURE 11 represents a single rod R which may, for example, be one of the rods in the rod bank 821 shown in FIGURES 8, 9 and 10, and the rod R would thus be mounted on a base plate 821a seated in a suitable groove in the top wall 814 and having its turbulence generating face F slanted at an obtuse angle of X-13 (of approximately from the top wall. The turbulence generating slanted (upstream face F on the rod R) has a groove G therein which is tapered slightly in the region of the base plate 121A, but which is substantially uniform in depth down to the rounded end E for the entire length of the front face F on the rod R. It has been found that this groove is unusually satisfactory in avoiding the tendency for strings to collect and/ or be stapled upon the rods in the rod bank.

Although it is not desired to limit the invention to any particular theory, attention is directed to FIGURE 13 which shows a cross sectional view of an ordinary cylindrical rod R with an upstream turbulence generating face F about which is wrapped a fiber string H having two trailing ends H and H which tend to become entangled in the stapling process. The stock stream flow is in the direction indicated by the arrow ST. It will be appreciated that when the central part H of the string is finally in contact with the turbulence generating rounded front surface F of the rod F, the velocity component of -the string portion H becomes approximately 0, whereas the pressure with which the stream urges the string portion H against the turbulence generating face F' reaches a maximum. It will be seen that the dotted line I shown in FIGURE 13 plots the impingement pressure along an assumed abscissa (x); whereas the points on the abutment generating surface F are plotted along an assumed ordinate (y). It will thus be seen that the maximum pressure J is obtained opposite the central part of the turbulence generating face F at H but at about 33 above or 33 below the point H (for example at the point H the impingement pressure is indicated as approaching zero. It will thus be seen that when a string such as the string H hits the rod R at approximately its mid point H the dragging effect of the stock stream on the tWo trailing ends H and H is not appreciably different and with a maximum compressive pressure J there is a tendency for the string H to remain on the face of the rod R. It will be appreciated that the angle of tilt or angle of slant X (hereinbefore described) will serve to create a slight velocity component parallel to the rod axis, so that slanting surface for the turbulence generators does assist in moving strings along the rod surfaces before substantial additional fiber particles are collected thereby. The improved turbulence generating surface F shown in FIGURE 11 and shown in FIGURE 12 in greater detail, however, is distinctly superior from the point of ivew of eliminating the creation of the situation whereby the central portion of the string H is subjected to a maximum impingement pressure component 1 As indicated in FIGURE 12, the groove G on the front turbulence generating face F of the rod R precludes the sticking of the central portion H of a string H to the front surface of the rod R by the application of maximum impingement pressure (i.e., J in FIGURE 13). Instead, the central groove G is so formed that the central portion H of the string H will not even come in contact with the solid surface of the rod R. The central portion H of the string H will thus not be stabilized in position on the front face of the rod R and in this unstable position the string H tends to slip off the face F of the rod much more easily in ordinary stock fiow.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. In a tapered approach to a paper machine slice opening defined by converging top and bottom walls for flowing a stock stream filling such tapered approach through the slice opening and on to a formin surface comprising a first multiplicity of spaced generally cylindrical rods extending from one of said walls substantially the depth of the stock stream and across the width of the stock stream for generating a first substantially uniform pattern of small scale turbulence of a first order of magnitude in the stream, a second substantially greater multiplicity of spaced generally cylindrical rods downstream from said first multiplicity and substantially smaller in size extending from one of said walls substantially the depth of the stock stream and across the width of the stock stream for generating a second substantially uniform pattern of smaller scale turbulence in the stream and a perforated plate extending transversely to the stock stream flow upstream from said first multiplicity for converting the stock stream under pressure to a plurality of high speed jets and said perforations being aligned with said first multiplicity to impinge the jets against the rods thereof, each of said second multiplicity rods being secured to one wall and having an upstream face extending downstream to define an obtuse angle with the stock stream fiow direction of to to terminate closely spaced from the opposite wall, the improvement of each such upstream rod face having a longitudinal groove therein to minimize stapling of fibrous stock elements to the face of the rod.

2. In a tapered approach to a paper machine slice opening defined by converging top and bottom walls for flowing a stock stream filling such tapered approach through the slice opening and on to a forming surface comprising said stock stream flowing through the approach in a generally rectilinear direction aimed at the slice opening, a plurality of spaced transversely extending turbulence generating rod banks with each bank spaced downstream from its immediate upstream bank to receive turbulence therefrom in partial decay, the downstream-most bank being spaced upstream from the slice opening to permit partial decay of its generated turbulence ahead of the slice opening, and a plate upstream of the upstream-most bank with perforations aligned with the rods thereof to impinge jets of stock thereagainst, each rod bank in downstream succession being formed of successively smaller rods with successively smaller spaces therebetween for generation of successively smaller scale turbulence in the stock and each of the rods in the downstream-most rod banks extending at a downstream slant from one wall to closely spaced relation from the opposite wall, the improvement of each rod having the slanted upstream face thereof defining a longitudinally aligned shallow recess to minimize stapling of the fibrous stock elements to the face of the rod.

3. In a tapered approach to a paper machine slice opening defined by converging top and bottom walls for flowing a stock stream filling such tapered approach through the slice opening and on to a forming surface comprising said stock stream flowing through the approach in a generally rectilinear direction aimed at the slice opening, a plurality of spaced transversely extending turbulence generating rod banks with each bank spaced downstream from its immediate upstream bank to receive turbulence therefrom in partial decay, the downstream-most bank being spaced upstream from the slice opening to permit partial decay of its generated turbulence ahead of the slice opening, each rod bank in downstream succession being formed of successively smaller rods with successively smaller spacers therebetween for generation of successively smaller scale turbulence in the stock and each of the rods in the downstream-most rod banks extending at a downstream slant from one wall to closely spaced relation from the opposite wall, the improvement of each rod having the slanted upstream face thereof defining a longitudinally aligned shallow recess to minimize stapling of the fibrous stock elements to the face of the rod.

References Cited by the Examiner UNITED STATES PATENTS 1,909,150 5/ 1933 Bell-Irving et al 162-347 2,881,674 4/1959 Johnson et a1 162216 2,929,449 3/ 1960 Mardon et a1. 162338 3,014,527 12/1961 Beachler 162-347 3,092,540 6/1963 Parker 162-343 FOREIGN PATENTS 370,422 2/ 1923 Germany.

DONALL H. SYLVESTER, Primary Examiner.

MORRIS O. WOLK, Examiner.