US3002621A - Pulp screen - Google Patents

Description

Oct. 3, 1961 w. F. MATHEWSON4 PULP SCREEN 8 Sheets-Sheet 1 Filed Jan. 28, 1957- m CM Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 2 Filed Jan. 28, 1957 rm/W57 Oct. 3, 1961 w. F. MATHEWSON 3,002,521

PULP SCREEN Filed Jan. 28, 1957 8 Sheets-Sheet 3 f v alian-QM A T rams 5y Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 4 Filed Jan. 28, 1957 Oct. 3, 1961 w. F. MATHEWSON 3, 1

. PULP SCREEN Filed Jan. 28, 1957 8 Sheets-Sheet 5 HTTOR/VEY PULP SCREEN 8 Sheets-Sheet 6 Filed Jan. 28, 1957 0 0 W M M C N m m m a W32 m w a 2- M 1J6 6 4 M Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 7 Filed Jan. 28, 1957 IA/I/EAI T017 W/L FRED EH19 T/IEWfO/l mam v t 3, 1961 w. F. MATHEWSON 3,002,621 I PULP SCREEN 8 Sheets-Sheet 8 il m vm rol? 74 mums-,0 lV/YTHZWMA/ United States Patent 3,002,621 PULP SCREEN Wilfred F. Mathewson, 261 St, Weymouth 10, Mass. Filed Jan. 28, 1957, Set. No.'636,807 8 Claims. (Cl. 209250) This invention relates to pulp screens and particularly to pulp screens of the type provided with a cylindrical screen'member having a cylindrical screening wall and which rotates about a horizontal axis, and means for delivering unscreened pulp stock to the interior of said screen member, the screening operation involving the 110w of the acceptable portion'of the pulp stock through the screening wall from the interior isms exteriorthereof.

One object of the present invention is to provide a novel screen member of this type in which the screening wall has an increased screening area, with the result that the screen will deliver an increased percentage of acceptable stock from any given amount of nnscrleened pulp stock during any one screening operation.

Another object of the invention is to provide a novel screen member in which the screening wall is formed of a flat wire which is bent edgewise into the form of a cylindrical coil, the adjacent turns of the coil being spaced from each other a distance to provide screening'slots of the desired width.

A still further object of the invention is to provide a pulp screen of this type in which the unscreened stock is delivered onto the interior face of the cylindrical screening wall in the form of a sheet which extends from one end to the other of the screen member.

Another object of the invention is to provide a pulp screen of the above type in which the opening through which the unscreened stock is introduced into the casing and the openings through which the screened stock and the tailings are discharged from the casing are located in the same end of the casing.

Another object of the invention is to provide a novel pulp screen which is so constructed as to facilitate the removal of the cylindrical screen as a unit from the casing. Other objects of the invention are to improve pulp screens in various ways which will be set forth in the following description.

,In the drawings:

FIG. 1 is an eievation showing the .end of the pulp screen through which the unsereened pulp stock is .delivered thereto and screened stock and t-ailings are disharge FIG. 2 is a view showing the other 9nd of thepulp scr e FIG. 3 is a section on the line 3.,,-3, FIG. 1-;

MG. 4 is a section on the line 4-74, FIG .:3;

FIG. 5 is a section on the line 5?5, FIG. 3;

FIG, 6-is an end view of the screen -,elem ent-;

FIG. 7 is a section on the line '7T-7, FIG. 5;

FIG. 8 is a perspective view of the driving gear by which the :screen element is rotated;

FIG. 9 is a fragmentary perspective Niew of -.a portion o th an pl of t e cy ndr cal screen element;

G- 0 -a .t a en a y pe spe ve ri ewsshowin a det ilo t e ssreenel m m;

.11 i .as .ma y:sestiesal wiew of thetser en e ment;

HQ .12 i a t esm marv e t nal ew ho in the m nne is ich them c e edpulp-s oc i de ve ed nt nterio ra e-Qt t s re nin o hes een clea es Ils n b sc ee emb dyin thi inv nt o ml des 1a casing, indicated generally at 3, and a cylindrical sereeg:

elemen ind a d .-.se.n. a y at 4. which i .1Q9%$ -t 3,662,621 Patented Oct, 3, 196 1 in the casing and is mounted for rotation about a horizontal axis," said screen element having a cylindrical screening wall indicated generally at 5 and which will be hereinafter described in detail. The casing ,3 inoludes two end members and a body portion which encloses the screen member. One of theend members is indicated at 6 and the other at 7. The body portion includes a bottom body member 8 and a top body memher 9. The bottom body member 8 is secured to the inner face 10 at the end member'6, said bottom body member having a downwardly projecting flange 11 which overlies said inner face 10 of the end member 6 and is secured thereto by bolts 12.' The bottom body member it extends through the end member 7, as best seen in i8. 3, and is provided with an outwardly extending flange 13 which overlies the outer face of the end mem her I of the casing and is bolted thereto by suitable bolts 14.

The end wall of the casing which is seen in FIG. 2 and which constitutes the right hand end wall in FIG. 3 :iS constituted by a plate 15 and a removable closure member 16. The plate 15 is bolted to the flange 13 of the bottom body member 8 by the bolts :14 above referred to, and this plate together with the closure member 16 constitutes the complete end wall for the casing. The closure member 16 is shown as a circular member, the lower peripheral half of which is removabl-y mounted in a semicircular support member 1-7 which is bolted to the end plate 15 by bolts 17a and is shaped to provide a groove 13 in which the lower edge of the tale, sure 16 is received, as best seen in IG. 3.

This closure may, if desired, be made of some parent material so that the screening operation the cas g may be observed.

T nd m m 6 has the general s p s own i FIG. 1 and constitutes the closure for the opposite .end of the easing,.-that .is, the left hand end in FIG. 3, The upper por of he s g bove th end member 6.-i.s closed by a plate 19 which is secured by bolts 21 to a flange 29. with which the e d n mbe s P 0 The upper body member 9 encloses the upper half of he sc en m b 4 a d t e lower ed o sai upper member are secured to the top edges of the lower body member by means of bolts 22.

he screen mem e 4 s moun n a sha t 23, n an i w ic i PPQ s i ro ler ea n s .4 c rr ed y t nd memb r's t e h r and of t e shaf b in .s p Q i b rin W thin th scr en 4 a l be p tl e crib d- The s insi is l s r en elemen -;itw u s n en s pp t n plate 25 t w sk: ne a d Pi th s e n walla is rigidly secured and which is fast on one end of the ha 3- Ills end-P ate 2. t u closes n end-of the y l ca sc een ement- The t e end or t 'd i s r e e em n s o e asser s n an la plat w h c o s as a s l h ua d n i h a le to as ef a d an 0f the s reeni -wa l a shown best in F168. This annular plate 26 has ,acentral op .27- e e d-p a e 2 hu car i th i 1 wei s -te n me ber a j sho n a be n -re n orces by radially ,extendingribs 254.

It has been stated above that one end of the shaft on which the screen member is .rnounted has a supporting bearing 24 in the end member .6. The other .end or the shaft, that is, the right hand end in F16 3, is supported in a bearing carried by a core member 28 which is lo.- cated within the screen member 4 and is rigidly secured to the inner face of the end member 6 by means of bolts 29, saidcore member having an outwardly projecting flange 30 through which the bolts 29 extend. Said cope member 2 i pr vi e w t -a ea box Por ion 1 ich ha a ch mb whisk i r cei ed a ear 3 by i h vided with roller bearings 35 in which the gear 33 is mounted, and since said core member is rigidly connected to the end member 6, it provides a substantial and fixed support for the bearings 35 and hence for the gear 33. The shaft 23 is thus provided with suitable bearings at each end thereof. If desired the shaft 23 may be enclosed in a tubular member 102 which extends from the :end member 6 to the gear box 31.

- The jaw clutch connection between the gear 33 and the .hub 34 of the plate 25 is illustrated in FIGS. 8 and 9.

The gear 33 presentsa hub portion 36 which extends through the end wall 37 of the gear casing 31 and which is provided with the jaw projections 38 which have an interlocking engagement with complementary jaw projections 39 with which the hub 34 of the end plate 25 is provided. Said end plate is secured to the hub 36 of the gear 33 by means of bolts 40 which extend through the hub portion 34 of the plate and screw into screw-threaded sockets 40a with which the hub portion 36 of the gear 33 is provided.

The gear 33 by which the cylindrical screen is rotated may be driven in any suitable way. As herein shown,

there is provided a motor 41 mounted on a motor support 42 that is secured to the end member 6. This motor has a driving pulley 43 which is connected by a belt 44 with a pulley 45 on a drive shaft 46 which extends through the end member 6 and into the gear box chamber 32. The outer end of the drive shaft 46 is supported in a roller bearing 48 carried by the end wall 37 of the gear box chamber and said shaft 46 has fast thereto a small gear 49 which, in the embodiment herein shown, is connected to the gear 33 through a reducing set of gears. As herein shown, the gear 49 meshes with a larger gear 50 which has integral therewith a small gear 51 that in turn meshes with the gear 33, as best shown in FIG. 5.

The wall 37 of the gear box is shown as a removable element, it being secured to the wall portion 53 of the gear box by suitable bolts 54. The gear element 50, 51 is shown as mounted in roller bearings 55, 56, the bearing 55 being mounted in the main portion of the wall of the gear box and the bearing 56 being mounted in the removable cover portion 37. Said cover portion also has integral therewith an annular inwardly directed portion 48a in which the roller bearings 48 are supported.

The shaft 46 is shown as extending through a protecting tube 103 which extends from the end member 6 to the gear box 31.

The screening wall 5 of the screen member 4 is of the type which presents a plurality of parallel through slots, each of which has a width sufficient to permit the acceptable portion of the pulp stock to pass therethrough but which is insutficient in width to allow the unacceptable portion of such stock to pass.

In the construction herein shown the screening wall is made from a length of flat wire 76 which is bent edgewise into the form of a cylindrical coil having a diameter corresponding to that desired for the cylindrical screen memher, the turns of the flat wire coil being spaced apart the proper distance to provide the necessary through slots 64 in said wall. This cylindrical coil is supported by a plurality of supporting bars 62 which extend from one end of the screen member to the other and are located on the outside of the coil, each supporting bar having on its inner face a plurality of transversely extending grooves 63 in which the edge portions of the various turns of the flat wire coil are received, as best seen in FIGS. 10 and 11. The grooves 63 have a width equal to the thickness of the flat wire 76 and they are spaced from each other properly to maintain the turns of the coil in proper relative positions to form the through slots 64.

The supporting bars 62 are anchored at their ends in the peripheral portions of the end plate 25 and the annular end member 26 of the screen member. Each bar 62 has rigid therewith at each end a projecting stud which is screw-threaded at its end, the studs at one end of the bars being indicated at 65 and those on the other end at 66. The studs 65 of the various bars 62 extend through openings 67 in the peripheral portion 68 of the end plate 25 and are anchored in position by means of clamping 'nuts 69 which are screw-threaded to the ends thereof.

Said nuts may either be flat sided nuts adapted to be manipulated by a wrench or may be provided with a screw driver slot 70, as shown in FIG. 11, so that said nuts can be manipulated with a screw driver.

The studs 66 on the other ends of the bars 62 extend through openings 71 in a circular ring 72 and said ring is clamped to the bars by means of clamping nuts 73 screw-threaded to the studs 66. The ring 72 in turn is anchored to the peripheral portion 74 of the annular end member 26 by means of clamping bolts 75.

With this construction the screening wall 5 will present a spiral slot 64 extending circumferentially of the wall from one end of the screen element to the other, with a result that the said screening wall presents a maximum slotted area for screening purposes.

Inasmuch asthe screening wall of the screen element is supported entirely by the end plate 25, it may be desirable to provide means for reinforcing the screen structure to prevent any sagging or disalinement of the open end thereof.' For this purpose; there is provided an outer cylindrical shell member 1000f expanded metal which encircles the screening wall and one end of which is rigidly secured in some suitable way to the Peripheral edge of the end plate 25, and the other end of which is similarly rigidly secured to the peripheral edge of the ring 72.

The core member 28 which contains the gear box 31 is provided with a receiving chamber 77 which is located within the screen element and extends longitudinally thereof. This receiving chamber 77 has communication with an inlet opening 78 with which the end member 6 of the casing is provided, said inlet opening in turn communicating with an inlet pipe 79 through which uns7creened pulp stock may be delivered into the chamber The chamber 77 is formed with a delivery nozzle 80 which extends longitudinally of said chamber and which presents a delivery opening in the form of a downwardly directed delivery slot 81 through which the unscreened material is delivered onto the interior face of the screening wall 5. This delivery slot 81 extends s the full length of the screen element from one end to the other thereof and provides means whereby the unscreened pulp stock is delivered onto the interior face of the screening wall in the form of a sheet. The delivery slot 81 is preferably located closely adjacent the interior face of the screen, as shown in FIGS. 4 and 12, and approximately in a horizontal plane extending through the axis of the screen element. Since the delivery slot 81 is spaced slightly from the screening wall 5, the sheet 82 of unscreened pulp stock will have a vertical movement for a short distance below the nozzle slot 81 before it actually comes into contact with the interior face of said screening wall. The delivery move ment of the unscreened stock is in the same direction as that of the screening wall as indicated by the arrows in FIG. 12 and preferably the unscreened stock will be delivered through the delivery slot 81 under sufficient head so that the velocity of the sheet 82 of said pulp stock is substantially the same as that of the screening wall.

During the free downward movement of the sheet 82 encased of the pulp between the delivery-slot and the point where it contacts with the inner face of the screen, the fibres in the pulp stock will tend to aline themselves with the direction of flow and thus with the screening slots 64. This result is conducive to an increased flow of; acceptable portions of the stock through the slots. The increased screening area which the screening wall herein illustrated provides is another factor in produca screen member which will, during a single. screenmg operation, deliver from a given amount of unscreened stock an increased percentage of acceptable pulp stock and a reduced percentage of tailings..

The acceptable portion of stock which is screened through the screening wall 5 collects in a chamber 84 in the lower portion 8 of the casingand this chamber has communication with a discharge opening 89 with which the end wall 6 of the casing is provided. The acceptable portion of the pulp stock is thus discharged through the opening 89.

Any portion of the pulp stock which does not pass through the screening wall 5 will remain on the inner face thereof and will be carried by said screening wall into a position opposite a shower pipe 90 which is lo cated outside of the screen and which serves to flush from the inner face of the screen any pulp stock which remains thereon. This pulp stock, which constitutes the tailings, drops onto a deflecting apron 91 which forms part of the core member 28 and is collected in a chamber 92. Said chamber 92 has communication with a tailings discharge opening 93 with which the end memher 6 of the casing is provided and is delivered thereby to a suitable pipe connection leading to any desired location.

The shower pipe 90 is shown as located in a pipe casing 94 which forms part of the cover portion 9 of the casing. Said cover portion comprises the two sections 95 and 96 which are spaced from each other to receive the shower pipe casing 94, said casing being secured to the edges of the cover sections 95, 96 by means of suitable bolts 97.

I claim:

1. A pulp screen comprising a casing provided with an end member at each end thereof, a cylindrical screen element within the casing and having a cylindrical screening wall, an end plate closing one end of said screen element, the other end being open, means to rotate the screen element about a horizontal axis, a first chamber stationarily supported entirely within the screen element to receive unscreened pulp stock, said chamber having a delivery nozzle through which the unscreened pulp stock is deposited on the interior face of said screening wall in the form of a downwardly moving vertical sheet which is parallel to the axis of the screen element and is located close to said interior face in a horizontal line extending diametrically of the screen element, said casing having a second pulp stock, means to remove the tailings progressively from the portion of said interior face of the screening wall that is approaching the said delivery nozzle during the rotation of the screen element, a receptacle member within the screen element to receive the tailings that are thus removed, one of said end members of the casing having an inlet opening communicating with the first chamber and through which unscreened pulp stock is delivered to said first chamber, and also having an outlet opening communicating with said secand chamber and through which screened pulp stock is discharged from said second chamber, and further having a second outlet opening communicating with the receptable member and through which the tailings removed from the interior face of the screening wall are discharged.

2. A pulp screen comprising a casing having an end member at each end, a cylindrical screen element located within the casing and having a cylindrical screening wall and an end plate at one end thereof which closes said end, the other end of the screen element being open, a horizontalscreen-supporting shaft extending axially through the screen element from one end to the other and also through said end plate, the latter being fixed to said shaft, one of the end members having a first bearing for one end of said shaft, a bearing support secured to said endmember and extending into the screen element through its open end and substantially to the closed end thereof, said bearing supporting having a bearing for said shaft located adjacent the closed end of the screen element, and means to rotate said shaft and the screen member carried thereby.

3. A pulp screen comprising a casing having an end member at each end, a cylindrical screen element located within the casing and having a cylindrical screening wall and an end plate at one endthereof which closes said end, the other endof the screen element being open, a horizontal screen-supporting shaft extending an ially through the screen element and said end plate, the latter being fixed to said shaft, one of the end members having a first bearing for one end of said shaft, a bearing support secured to said end member and extending into the screen element through its open end and substantially to the closed end thereof, said bearing support having a bearing for said shaft located adjacent the closed end of the screen element, means to rotate said shaft and the screen member carried thereby, said other end member having an opening in line with the screen element and of a size to permit said screen element and the shaft by which it is supported to pass therethrough, and a removable closure for said opening which is separate from both the screen element and the bearing support, whereby said screen element and the shaft to which it is secured is removable as a unit from the casing or replaceable therein through said opening.

4. A pulp screen as defined in claim 3 in which the removable closure is of transparent material.

5. A pulp screen comprising a casing having an end member at each end thereof, a cylindrical screen element within the casing, a horizontal shaft on which the screen element is mounted, a bearing in one end memher for one end of said shaft, a stationary core member secured to said one end member and extending into the screen member, a bearing for the other end of the shaft carried by said core member, a driving gear axially aligned with the shaft, a bearing support for said gear carried by the core member and having a central opening through which said shaft extends, means to rotate the driving gear and a jaw clutch connection between the driving gear and said screen element.

6. A pulp screen comprising a casing having an end member on each end, a cylindrical screen element within the casing and having an end plate which closes one end thereof, the other end of the screen element being open, a horizontal shaft on which said end plate is fixedly mounted, a bearing in one end member for one end of the shaft, a core member secured to said one end member and having a portion located within the screen element, a bearing for the other end of said shaft carried by said core element, said core member having a gear box, a driving gear mounded for rotation in said gear box and having a central opening through which said shaft extends, means to rotate the driving gear, and a jaw clutch connection between said driving gear and said end plate of the screen element.

7. A pulp screen comprising a rotary cylindrical screen element having a cylindrical screening wall, means mounting said screen element to turn about a horizontal axis, a stationary chamber for unscreened pulp situated entirely within said screen element, said chamber extending from one end to the other of the screen element and being provided with a delivery nozzle having a downwardly opening elongated delivery slot extending parallel to the axis of the screen element and located closely adjacent the interior face of said screening wall in a. horizontal line extending diametrically of said 'screen element, said delivery slot being constructed to deliver the unscreened pulp in the form of a single sheet which flows downwardly vertically from said delivery slot onto a portion of the inner face of the screen element which is immediately below a horizontal diametrical plane through said screen element, whereby the downwardly moving sheet of unscreened pulp flows onto the inner face of the screen element at a small angle, and means to rotate the screen element in a direction in which said portion of the interior face of the screening wall is moving in the same direction as the sheet of unscreened pulp stock which is delivered thereon.

8, A pulp screen as defined in claim 7 in which the screening wall has screening slots extending circumferentially thereof whereby as the vertically moving sheet of unscreened pulp stock comes into contact with the inner face of the screening wall, said sheet is moving in the lengthwise direction of the screening slots.

References Cited in the fileof this patent- UNITED STATES PATENTS Alexander June 11, Goss July 7, Hang et al. June 18, tadler Feb. 2, Lawn Ian. 30, Mathewson Oct. 5, Mathewson Oct. 10, Fon tein June 5, Dubach June 5, Sandison'" July 3, Fontein May 6,

FOREIGN PATENTS Norway July 15, Great Britain July 22,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,002,621 October a, 1961 Wilfred F. Mathewson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification, lines 3 and 4, for "Wilfred F. Mathewson, 261 Franklin St. Weymouth l0 Mass." read Wilfred F. Mathewson, Weymouth, Mass. (261 Franklin St. Boston 10, iass.) column 5, line 56, after second insert chamber exterior to the screen member to received screened lines 65 and 66, for "secand" read second column 6 line 9 for "supporting" read support line 61, for "mounded" read mounted Signed and sealed this 3rd day of April 1962.

(SEAL) Attest:

' ERNEST W, SWIDER DAVID L. LADD Attesting Officer Commissioner of Paten

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