US1511759A - Method of and apparatus for screening paper stock - Google Patents

Description

m, 19%. MHJEQ A. J. HAUG METHOD OF AND APPARATUS FOR-SCREENING PAPER STOCK Fil ed No v. 21. 1919 4 Sheets-She l oeooooococoooqnoopoonouoc conoou 0 Hum u um @Wiim:

Wm. M, w mmung/59 A. J: HAUG METHOD OF AND APPARATUS FOR SCREENING PAPER STOCK Filed Nov. 21, 1919 I 4 Sheets-Sheet 2 A. J. HAUG METHOD OF AND APPARATUS FOR SCREENING PAPER sTOCK Filed Nov. 21 1919 4 Sheets-Shet z Um. M, a924 1,511,759

. A. .J. HAUG METHOD OF AND APPARATUS FOR SCREENING PAPER STOCK Patented @ct. let, i324 i it 1:15;. i

ANTON J. Have, or NASHU'A, NEW HAMPsnrnn AssIenoa T nurnovnn PAPER mncnrnnnv COMPANY, or nAsnUA, NEW HAMPSHIRE, A CORPORATION or MAINE.

METHOD OF AND APPARATUS FOR SCREENING PAPER 'IOCK.

Application filed November 21, 1919. Serial No. 339,562

To all whom 2'2, may concern:

Be it known that I, ANTON J. Thus, a citizen of the United States, and resident of Nashua, county of Hillsborough, and

b State of New Hampshire, have invented an Improvement in Methods of and Apparatus for Screening Paper Stock, of which the following description, in connection with,

lowing description when taken. in connec- 'tion with the accompanying illustration of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings Figure 1 is a central, longitudinal, sectional elevation of the inlet end of a-screen embodying one form of the invention;

Fig. 2 is a similar view showing the opposite or outlet end of the screen;

Fig. 3 is a transverse, sectional elevation taken on the line 3--3 in Fig. 1, looking in the direction of the arrow or toward .the inlet end;

Fig. 3 is a detail in section on the line 3 -3 in Fig. 2; a

Fig 3" is a similar section on the line 33 in Fig. 2;

Fig. 4 is a plan view of the devices contained within the screen drum for advancing the unsereened stock step by step; and

Fig. 5 is a plan view in section, taken on the line in Fig. 3, showing the separated feed passages for the stock.

Referring to the drawings and to the embodiment of the invention therein sub mitted for illustrative purposes, I have shown the same as embodied in a screening apparatus for paper stock, the principal screening member of which is in the form of a screen drum. While the latter may be of any desired shape and may be either rotatable or fixed, herein the same is rotatably mounted and polygonal in shape, the surface of the drum being formed by a series of flat, rectangular, perforated screen plates 10, herein eight in number, carried by the end plates 11 and 12, the latterbeing octagonal in. outline and secured to or fashioned integrally with the hollow journal members 13 and 14: respectively.

The entire drum is enclosed within a fixed casing or chamber having the encircling walls 15 secured to the opposite end frame members 16 and 17 respectively, the casing 15 at its bottom communicating with a suitable outletwpassage 18 (Fig. 3) through which the screened stock, which pass. es through the screen drum from the interior to the exterior thereof, may escape and be conducted to any suitable point. The out- .let for the screened stock is herein shown as provided with a weir-like plate 19 over which the stock flows and the height of which controls the level of the stock within. the casing. The plate 19 is held at opposite ends between guides 20 and 21 and may be replaced by a plate. of greater or lesser height to vary the stock level in the casing.

The casing and theend plate 16 rest upon any suitable support devices, such as the supporting feet 22, and provide a suitable journaled support for the rotary screen drum, the same being herein in the form of a plurality of roller supports 23 at each end, upon which rollers the journal members 13 and le'turn, rotationbeing imparted to thedrum by any suitable means such as the driving pulley 24 secured to the journal member 1 Q In the described embodiment of the invention, the stock to be screened is delivered to the interior of the screen drum at one end thereof, preferably through a continue ous supply; and as the drum is rotated the stock is screened and the unscreened residue lifted and dropped. The unscreened residue, having been first preferably thinned or diluted, is conducted by suitable feeding means which again deliver it to the drum but at an advanced point in its length so that substantially the same screening, lifting and dropping operation may be repeated. This is continued any desired number of times until the final unscreened residue is delivered to the tailings outlet of the machine.

Referring first to the devices for deliver ing the entering stock to the interior of the drum and for advancing the enclosed residue step by step through the drum, while prevented from. further advance and diverted against the'overfiow plate-49 (Figs.

tions. This repository for the stock is;

such devices may be variously constructed and maybe either movable or stationary, herein they .are contained in a fixed, trough-like structure which passes through the drum from end to end and is provided with suitably arranged passages to direct the flow of the stock in the proper direcsupported on a frame extending through the machine from end to end and consisting of the channel irons and 31 with the underlying connecting plate '32, the frame being supported at the inlet end by the bracket 33 secured to the adjacent supporting feet122': andy at' the outlet end, to brackets 84 which extendoutwardly and rearwardly fromlthe supporting feet 22 and end plate whereit communicates .with the inlet chamher 42': and the inlet opening 43, the latter being formed in the casting 4A which is secured to] the projecting endofthe casting-40. Theinlet passage tl llas a channelshaped depression 45 and the-inlet chamber :42 acorresponding depression, which depressiensforma..sand1trap or settling chamher adapted to receive depositsof" sand or other foreign matter which vmay settle or gravitateout: of: the stock-as the latter enters theinlet chamber and affords passage to thescreen drum; The end of the settling chamber isclosed bya movable closure 46 40,

from time totimeas required;

Thestock as itgfpasses through the inlet through which the chamber may be cleaned chamber 41 flows over the 'horizontal wall 47 of the casting until it encounters the diagonal partitionwallAS by which it is 3 and: 5), thelatter being of lesser height than the partition wall 48 and arranged longitudinally thedrum at one side of the axis thereof and preferably on the descending-side. thereof;' The stock 'passing'over the overflow plate-49passesdown the surface of. the. inclined" discharge plate 50 and is thereby delivered to the descending side of the drum, being preferably delivered.

thereto within certain longitudinal limits which-are prescribed by the upright partitionplates-cl' and 52vonIth-e discharge plate,

the-,.-plate 5.2 coinciding with or forming a continuation of the partition plate 48';

TlieStock whichis thus delivered to the drum, after being. screened and liftedfas will be more fully described) is dropped from the ascending side of. the drum at the opposite side of'the axis thereof where it again falls upon the flat plate 47 which at the ascending side of the drum is preferably inclined upwardly at. 53 (Fig.3) so as to' parts of the drum at one sideof the axis thereof (the descending side)" and is inclined downwardly toward the feed plate so that materialwhich is carried up toward,

to or pastthe center of the drum will drop on the deflectingplate and will gravitate uponthe flat plate 47. This material, however, gravitates upon the plate 47 at the back of or on the opposite side of the partitionwall 48, from' which the stock enters the drum, so that it is separated from the unscr-eened stock entering-through the inlet and is caused toflow through the diagonal passage formed between the partition wall 48 and a similar but more advanced partition wall (31- to a second overflow plate 62 on the descending side of the drum but at a more advanced point therein than the stock which is initially delivered. thereto from the inlet passage.

The stock which is thus deliveredto the drum past the overflow plate 62 for a second screening action is in turn screened, lifted and delivered to the feed plate 47011 the opposite side of the drum but between the partition wall 61 and a similar, more 1 advanced partition wall 64, the twoformagain delivered to the drum at a still more advanced point. This operation may be repeated any desired number of times, the feeding apparatus illustrated in Figs. 4 and 5 being provided with means for rescreening the residue from the firstscreening operation five times, consecutive partition walls 66, 67 and 68 being provided and overflow plates 69 and 70, similar to those already described. Since the repeated rescreening results in a gradual withdrawal of portions of thestoek and a step-by-step diminution in the amount rescreened at each time, preferably the successive passages in the feeding apparatus undergo a. gradual diminution in. available cross-sectional area, this being represented in Figs. 4 and'5 by a closer arrangement of the successive. partitions for successive feeding passages Between each screening action and the next, the unscreened residue in each case is preferably thinned or diluted since the rejections from each screening operation are considerably thicker than the initial supply. Suitable thinning or diluting devices are therefore employedin the illustrated embodiment of the invention, the same herein consisting of a shower pipe located in such position (and herein centrally above the axis of the drum and sup-ported by the feeding plate casting) that it is adapted to discharge a shower of water into and over the gravitating residue. and dilute or thin the same as it flows or moves toward the overflow plates 62 etc. This shower pipe extendstliroughfrom the outletyend of the machine where it is supported by a bracket 71 carried by the supporting brackets 34: and has connection (not shown) to any suitable source of water supply.

Additional shower pipes may be employed if desired and herein two suchrpipes 72 and 73 are shown located one directly above the drum within the casing 15 and the other above the ascending side of the drum, so that the shower water is directed upon the stock-lifting surface of the drum and assists to free the slivers and fibres contained in the unscreened residue from the foraminous surface of the screen plates as Well as assisting in diluting the stock.

After the last screening operation and after the unscreened residue or tailings have been delivered to the feed plate 47 between the partition walls 67 and 68, the residue passes over the edge of the plate whereat it is delivered to the inclined plate 81 (see Figs. 2 and 5) and flows through the tailings outlet channel formed by the channel irons 30 and 31 and the underlying plate 32, being delivered from the end thereof into any suitable receptacle such asthe tailings receiver 82.

Referring now to the construction of the screen drum, the latter, in the illustrated embodiment of the invention, is subdivided interiorly into separate stock-receiving compartments by means of partition walls "which extend-longitudinally the drum and are directedinwardly in a general radial. direction for a short distance. Each screening plate herein carries three such compartments (Fig. 3) which are formed by the two partition walls near the edge of the plate and the two intermediate partition walls 91. These partition walls are brought into successive registration with the discharge plate 50 as the drum rotates, so that the stock discharged by the discharge plate is delivered to the pockets and as the drum turns is more or less agitated as it is thrown from one corner of the compartment to the other. By means of the weir plate 19, a sufficient stock level may be ing blades which retain the unscreened residue until it is brought within the influence of the shower pipes 73 and 72 and is raised to a sufficient elevation to insure its delivcry to the feedplate 4L7. i

In the described embodiment of the invention, also, the screen drum is further subdivided longitudinally into separate screening compartments by a series of circumferential, ring-like plates 9292, these.

ring-like plates constituting partition walls which are located to coincide or register with the partition walls 51, 52, etc. which control the successive deliveries of stock to the successive portions of the drum, and also to register or coincide with the successive partition walls :8, 61, etc. on the feed plate and which confine the unscreened residue as it is delivered thereto by the drum to such a path as insures its redelivery to the drum in the next succeeding circumferential. compartment thereof. These circumferential partition walls therefore subdivide the drum into compartments corresponding to the successive feed passages of the feeding plate so that at each successive rescreening the unscreened stock is confined to a part of the drum where it is separated from portions of the stock which have been subjected to a greater or lesser number \of screenings, thus insuring that all stock delivered to the drum will be subjected to substantially the same screening eifect before being rejected at the tailings outlet.

As a simple and etlicient means of constructing the screen drum, the perforated plates 10 are carried each by a grid-like support which extends from one end plate 11 to the opposite end plate 12, the opposite ends of each plate being fastened by the bolts (Fig. l) to the end ring.

Each grid-like support is composed of the longitudinal partition. walls 90 and 91 and the segmental, circumferential partition walls 92. When the several supports are bolted in position to the end plates, they form a skeleton support for the perforated plates 10 with the corresponding circunr ferential partition walls in registration so as to constitute the circumferential partitions 92.

The partition walls 90 at the edge of each grid-like support are considerably thickened at the base or where the plate 1.0

is adapted to rest thereagainst so that when perforated portions of the plates 10 If desired, at suitable points longitudinally in the adjacent partition walls 90 the adjoining supports may be bolted together by means of bolts 101 (see Fig. 2 and the section Fig. 3*). To secure the plates to the d rum, means are herein employed which eifectively hold them in position and at the sametime assist in drawing the thin plates flat upon the. support. For this purpose, herein the adjacent edges of adjoining plates are engaged by the beveled or wedgeshaped: strips 102, the face of each strip being engaged at intervals by beveled face clamps, each clamp consisting of a pair of clamping members 103 which are drawn together by the'bolt 104, the bolt being anchored or held against a radial outward movement by a strap 105 which is secured to a pin 106 arranged transversely'in the underlying and adjoining partition walls 90.

As the bolt 104 is tightened, theclamps are i drawn together andthis in turn binds the edges of the plates 10 tightly to the grid-like supports and tends to stretch them fiat thereon. At opposite ends each plate-is similarly clamped to the end plates 11 and 12 respectivelyby the wedge-shaped strips 107 clamps 108 and clamping bolts 109 (Fig. 1).

The drum is thus actually made up of segmental units, each unit serving as the-sole P support for the plate corresponding to that segment. Therefore any one plate or any one segment maybe removed and replaced without dismantling the drum.

Preferably, at each opposite end of the casing removable closures are provided such as'the closures 110 and 111 throughwhich an inspection of the interior of the apparatus may be had at any time and through which anytrouble maybe corrected which arises, such for example as aclogging ofthe feeding passages or improperlyworking shower pipes. The end plates 11 and 12 are provided withsuitable' openings 112 through which inspection of and access to the interior of the drum can readily be had through the respective inspection openings.

1 The-feeding passages of the feed platebeing opened and exposed, any tendency to clog or obstruct the feed .is reduced to a minimum and, if or whenit occurs, can be easily ascertained through the inspection. openings referred to.

To provide against an accidental stoppage of the drum rotation, as for exampleby the slipping of the drive belt, an overflow may be provided which will take careof stock in the drum likely to accumulate before the feed of the stock supply can be shut ofi. For this purpose the end. plate 17 hasan overflow opening 113 fromwhich there projects an overflow spout 11 i throu h which stock may escape over the weir p ate 115,

in case the drum, through any such ac cidental stoppage, becomes filled with stock to a height sufiicient to permit it to escape through the openings 112 in the endplate 12.

In order to better adapt the tailings to.

some subsequent process of refinement or for some other reason, it may be desirable to thicken the-consistency of the tailings by. T8. moving some of the moisture which they have when discharged. For this purpose I have shown the screen near its tailings outlet equipped with a drying device adapted to remove water from the taihngs, such drying device herein'consisting of the rotary,

cylindrical, fora-minous drying drum 120 which is secured to the end of the journal member 14 to turn therewith about the tailings outlet passage. thicken the ta1l1ngs, a cover plate 121, which is normally used to cover an opening 122 in the bottom of the tailings passage, is removed so that the tailings are discharged through the opening 122 into the draining drum 120. The latter is slightly flared. or.

longitudinally tapered so that as the drum;

turns the tailings are slowly advanced to.-

ward' the mouth thereof until discharged;

into the tailings receptacle 82. Inthe course. of their advance through the drum, how

ever, they are agitated more or less and;

rolled over and over asthey are carriednp the ascending side of the drum. This ex,- tracts more I or less water from. the stock, which water falls into the underlying chamber 123, escaping through the passages 12% which lead downwardly and inwardly through the end plate 17. into the-screened stock chamber. The exposed portion of the tailings discharge passage and the draining drum 120 may becovered. for.- protection by. the removable, se1nicylindrical cover130.

Thedelivery of the shower pipe 70, as.

well as that of the pipes 72 and 73, isrcone fined to an area within the main casing 1.5, so that there is no further dilution of the tailings after they enter the draining drum 120. 1

.VVhile I have herein shown anddescribed for purposes of illustration, one specifiee1nbod'iment. of the invention, it is to be understood that the same is not limited to the details of construction herein'shown or to. the form or relative arrangement of parts,

If it is desired to.

but that extensive deviations may be made therefrom without departing from the spirit of the invention.

Claims:

1. A screening apparatus for paper stock, the same having a rotary screen drum the interior of which is subdivided longitudinally into separate screening compartments whereby the stock delivered to the inlet end may be screened, lifted and dropped by the rotation of the drum, and stock-advancing means comprising a repository for the dropped stock with separate passages, one for each screening compartment, adapted to advance the residue. from each screening operation and deliver it to the next or more ad vanced compartment of the drum, said passages at their receiving end registering with the delivery from one compartment and at their delivery end with the next adjacent compartment of the drum.

2. A screening apparatus for paper stock, the same having a rotary screen drum the interior of which is subdivided longitudinally by circumferential partition walls into separate screening compartments and is subdivided circumferentially by longitudinally arranged partition walls, whereby the stock delivered to the inlet end may be screened,

lifted and dropped by the rotation of the drum, and advancing means comprising a repository for the dropped stock with separate passages, one for each screening compartment, and adapted to advance the residue from each screening operation and deliver it to the next, more advanced compartment of the drum, said passages registering at their receiving end with the delivery from one compartment and at their delivery end With the next adjacent compartment of the drum.

3. A screening apparatus for paper stock, the same having a rotary screen drum subdivided both circumferentially and longitudinally into screening compartments, said drum, having an inlet at one end whereby stock may be delivered to the drum and an outlet at the opposite end wherebiy the tailings may be withdrawn there rom, and means to receive the tailings emptied from each screening pocket as the same are lifted in the course of rotation of the drum and deliver the same to a screening compartment on the next or more advanced series for a repetition of the screening o eration.

4. A screening apparatus or paper stock, the same having a rotary screen drum subdivided both circumferentially and longitudinally into screening compartments, said drum having an inlet at one end whereby stock may be delivered to the drum and an outlet at the opposite end whereby the tailings may be withdrawn therefrom, means to receive the tailings emptied from each screening pocket as the same are lifted in lengthwise the drum, a stock repository device extending through the drum and presenting feeding passages adapted to receive stock from one compartment and advance it to the next, each of said passages having partition walls which coincide at their stockreceiving end with one compartment and at their delivery end with the circumferental partition walls of the next adjacent compartment.

6. A screening apparatus for paper stock, the same having a rotary screen drum the interior of which is subdivided by circumferential plates to present separate screening compartments, each compartment being also subdivided longitudinally by plates, toprovide lifting blades for the separate compartments, said drum having an inlet through which stock tobe screened may be delivered to a compartment near the inlet end and screened, lifted and dropped through the rotation of the drum, and stockadvancing and feeding means whereby the residue from each screening operation is advanced and delivered to a more advanced compartment in the drum for a repetition of the screening operation, the same comprising a repository member in the form of a plate having dividing walls presenting open passages adapted to conduct the deposited residue diagonally from the point deposited at one side of the drum axis to a more advanced point on the opposite side, thereceiving end of the passages registering with the delivery of one compartment of the screen and the discharge registering with the next more advanced compartment.

7. A screening apparatus for paper stock, the same having a rotary screen drum by which the stock is screened, lifted and dropped, and stock-advancing or feeding means comprising a trough-like repository consisting of a plate with dividing walls to present uncovered passages adapted to conduct the deposited residue diagonally from a point on one side of the drum axis to a more advanced point on the opposite side and thereat deliver it again to the drum.

8. In a screening apparatus for paper stock, the combination with a screen drum adapted to screen, lift and discharge the unscreened residue through the rotation of the drum and means for delivering the unscreened residue fro-m any screening operation again to the drum, the same having diagonally arranged feeding passages 10- catedi above'the axis of the drum and terlatter drum.

stock, the combinationwith a screen drum 'minating at'an inclined discharge plate, the providing a path to the underlying 9.1;In' a screening apparatus for paper adapted to screen, lift and discharge, the unscre'ened residue through the rotation of the drum and means for delivering the unscreened residue from any screening operation again to the-drum, the same having 1 diagonally arranged and open feeding passages located above the axis of the drum. 10. The combination with a rotary screen v drum of means to deliver stock within said drum, the; stock. being screened and the residue lifted and dropped, and means todeliverthe residue again to said drum, said means including a feeding plate with diagonally arranged uncovered feeding passages thereon;

11;.An apparatus for screening paper stock: having a rotary screen drum provided with interior lifting blades; said drum beingj adapted to screen the stock and lift and drop-the uns'creened residue, and means for advancingthennscreened residue with-- infthe drum, the same including a downwardly directed discharge plate adjacent the bottom of the drum withthe end of which theliftingbladesare, adapted to register in succession as the drum rotates.

12. An apparatus for screening paper stock, the-same having a rotary'screen drum adapted to screen the stock, lift and drop the same, and means for advancing-the stock-within said drum, the same including a substantially flat. plate provided with diagonally arranged feeding. passages.

' 1 3; -An; apparatus for screening paper stock, the same having a rotary screen drum adapted to screen the stock, liftand drop the same, and means foradvancing the stock -ly arranged feeding within sai'd.,drum,}the same including a substantially flat plate provided with diagonalpassages and an overflow wall for each passage.- 7

14. An apparatus for screening paper .downwardly directed discharge plate for vconductingthe unscreene'd residueto the des'cending sideof the drum. p g e 1115, A screening apparatus includinga rotary screen drum with circumferential partition compartments and stock-advancing means including delivery passages having partition walls confining the, delivery thereth coinciding With the circumfe efit se en-ments 1 6, A rotary. screen drum" having a foram nous surface and subdivided into screening compartments by longitudinal partitions, saidzcompartments being further subdivided circumferentially.

17. In an apparatus for screening paper stock the combination with a screen drum having a polygonal cross-section, the interior being divided into screening com )artments by longitudinal subdivisionsan the compartments being subdivided into successive series by circumferentially arranged partitions, of stock advancing devices adapt ed to receive stock from one compartment and deliver it to a more advanced one.

18. In an apparatus for screening paper stock the combination with a screening drum having a foraminous surface and subdivided interiorly bot-h circumferentially and longitudinally into separate screening compartments by unperforated partition walls, of stock advancing devices adapted to receive stock from one compartment and deliver it to a more advanced one.

1.9. Inan apparatus for screening paper stock, the combination with a screening drum, polygonal in cross-section and presenting successive, flat, foraminous faces,

.each' flat face being interiorly subdivided by longitudinal partition walls into separate screening compartments, of stock advancing devices adapted to receive stock from one compartment and deliver it to a more advanced one.

'2 20. In an apparatus for screening paper stock, the combination with a screening drum having a polygonal cross-section and having one or more longitudinal partition walls between each vertex of the polygon to separate each flat face thereof intcriorly into two or more screening compartments, of stock advancing devices adapted to receive stock from one compartment and deliver it to a more advanced one.

21. A screening drum'polygonal in cross section and sepaatcd interiorlyand longitudinally into separate screening compartments and a partition member located at .or near the junction of two adjacent fiat faces and havingpartition walls which converge inwardly.

, 22. A screen drum having a polygonal cross-section separated interiorly into longitudinal screening compartments and a partition member between two adjacent compartments and located atthe juncture of two adjacent-faces of the drum, said partition member being thickened at the point nearest the drum face.

23. A rotary screen drum subdivided interiorly into separate screening pockets by longitudinal partition members, one of said partition members having partition walls which converge inwardly.

24. A polygonal screen drum havin end supports, aforaminous wall for eac flat face of the drum, a grid like support for each foraminous wall adapted to be fastened at opposite ends to the end supports and to present each a plurality of longitudinal walls adapted to constitute stock-lifting blades and a plurality of transverse walls adapted to register in adjacent supports and when assembled to constitute interior circumferential partitions, the adjacent supports presenting longitudinal walls closely adjacent one another and converging inwardly toward each other.

25. A screen drum having a polygonal cross-section, end supports and a foraminous wall for each flat face of the drum, a gridlike support adapted to be fastened at opposite ends of the end supports and presenting each a plurality of longitudinal walls adapted to constitute stock-lifting blades, the adjacent supports presenting longitudinal walls closely adjacent each other and converging inwardly and towards each other.

26. A rotary screen drum having a foraminous surface and composed of a plurality of grid-like members secured at opposite ends to suitable end supports and serving as a support for the foraminous covering, said grid-like members presenting longitudinal partition walls adapted to serveas interior stock-lifting blades for the drum.

27. A rotary screen drum comprising end supports, a foraminous covering and a support for the foraminous covering, the same including a plurality of separate supports fastened at their opposite ends to the end supports and presenting longitudinal blade members adapted to subdivide the interior of the screen into separate screening compartments.

28. A rotary screen drum comprising end supports, a foraminous covering and a support for the foraminous covering, the same including a plurality of separate supports fastened at their opposite ends to the end supports and presenting segmental, circumferentially arranged partition members.

29. In a screening apparatus, a rotary screen drum having a polygonal cross-section with means for supplying stock to the interior of the drum, said drum being composed of end supports with a connecting grid-like supporting member for each flat face of the drum and a fora-minous plate secured to said supporting member.

30. A rotary screen drum having a foreminous covering and a support therefor com prising end supports and a series of apporting units connecting the same, each unit providing a seat to which opposite edges of the foraminous covering is applied and also presenting interiorly arranged, stoclelifting blades.-

31. A rotary screen drum having a forarninous covering and a support therefor formed of sectional segments, each segment comprising a supporting member for the foraminous cover and presenting subdividing partition. walls for the interior of the drum.

32. A screening apparatus for paper stock having a rotary screen drum provided with means for screening the stock and lifting and dropping the unscreened residue, means for advancing the unscreened residue between each screening operation and the next, a stock inlet through which stock is deliv ered to one end of the drum, said inlet having a settling chamber to receive sand and other impurities.

33. A screening apparatus for paper stock having a rotary screen drum provided with means for screening the stock and lifting and dropping the unscreened residue, means for advancing the unscreened residue between each screening operation and the next, a stock inlet through which stock is delivered to one end of the drum, said inlet having a settling chamber to receive sand and other impurities and having also a cleaning opening for said settling chamber.

34. A screening apparatus for paper stock having a rotary screen drum, stock inlet means and a settling chamber for said stock inlet means adapted to receive sand and other impurities.

i A screening apparatus for paper stock having a rotary screendrum, stock. inlet means and a settling chamber for said sto l: inlet means adapted to receive sand and other impurities, said chamber having a cleaning opening.

36. A screening apparatus for paper stock, the same having a rotary screen drum with means for screening the stock, lifting and.

dropping the unscreened residue, means for advancing the stool; after each screening operation, means for diluting the stock between each screening operation and the next, a tailings delivery outlet and means for thickening the tailings.

37. A screening apparatus for paper stock, the same having a rotary screen drum with means for screening the stock, lifting and dropping the unscreened residue, means for advancing the stock after each screening operation, means for diluting the stock between each screening operation and the next, a tailings delivery outlet, a tailings drying device and means for diverting the tailings at will to said drying device. 7

38. A pulp screen for screening paper stock in comprising a screen drum having stock-lifting walls and means for rotating the crum whereby the stock is screened and the unscreened residue lifted and dropped by said liftingwalls, means fOr diluting the thickened residue, devices to receive the discharged residue and divert and deliver it to said drum at a more ad vanced point therein for a repetition of the screening action, and a draining drum to receive the tailings, outside of the actionof saidfdiluting means, whereby the consistency' of said tailingsmay be thickened.

39.. A pulp screen for screening paper 7 stock; in stages comprising a screen drum having stock-lifting walls and means for rotating the drum" whereby the stock is screened and the unscreened residue lifted and dropped by said lifting walls, means "for diluting the thickened residue, devices to receive the discharged residueand divert "and delivert to said drum at a moread- 'vanced point therein for a repetition of the thickening the 'tailings.

iOJA 'pulp screen for screenlng paper stock in stages comprising a screen drum screening action, and drying means for having stock-lifting walls and means for rotating the drum whereby the stock is screened and thennscreened residue lifted and dropped by said lifting walls, means for diluting the thickened residue, devices ;to receive the discharged residue and divert and deliver it to saididrum at a more ad i .vanced point therein for a repetition of the ll. A

; screening action, drying means for thieken ring the tailings and means for discharging I the tailings at Wlll \Vlt-ll or wlthout the action thereon of said drying means.

screening apparatus for paper stQck,'the same'havin'g a rotary screen drum, acasing'therefor, means whereby stock may be screened by said'drum and the residue liftedand dropped, feeding means for advancing the unscreened residue and deliver- 'ingit again to the drum, and one or more I removable closures in said casing to permit "a casing therefor, means whereby said drum is adapted to screen the stock and lift and drop the unscreened residue, a stock reposiaccess to vthe interior of the drum. 412; A screening apparatus for paper stock, the same having a rotary screen drum,

tory for taking theunscreened residue and redelivering it to the drum at a morev advanced' point, the same comprising a sta- ,overflow openings topermit the overflow of tionary feed member having diagonally arranged feed" passages therein, and one or moreremovable closures for said casing to provide access to said feed member 43. A screening apparatus for paper stock, the same comprising a rotary screen drum, a 03.811121 therefor and means for feeding stock to the nterior of said drum, said casingand said drum having cooperating said stock in the said drum.

44;. A screen, drum having a foraminous covering, a support therefor presenting a seat onwhich the covering rests and means for securing said foraminous covering to event of the stoppage of the'support, the same including aiclamping device with a clamping face beveled or inclined with relation to the seat.

1-5. A screen drum having a polygonal cross-section and a foraminous cover composed of fiat foraminous plates, an underly ing support and i'ueans presenting a seat on which the covering rests for securing the plates to said support, the same including a beveled strip overlying the edge of the plate and one or more clamping devices engagingsaid strip, the clamping faces of said strip and device being incline-d or beveled with relation to the seat.

46. A screen drum having a polygonal cross-section and a formaminous covering composed of a plurality of flat foraminous plates, and means for securing'theplates to an underlying support including beveled strips overlying the edges of adjacent plates and wedge-shaped clamps engaging the edges 'of the strips and adapted to be clamped together to hold said plates in position. I

4?. A screen drum, polygonal in crosssection and having a foraminous covering composed of flat foraminous plates and means for fastening theedges of said plates to an underlying seat or support for the same comprising a clamping device and an intermediate member interposed. between the clamping device and the face of the plate, said members having cooperating eugaging faces inclined at an angle to the seat on which the plate rests 48. The combination with a screen having a tailings outlet ofa drying device comprising a, rotary draining drum adapted: to receive said tailings on its inner surface and drain the Water therefrom, said drum having separate discharge passages for the water and the thickened'tailings. V 49; The combination with a screen having means for screening paper stock and for V diluting and rescreening the unscreened resi- V vate and discharge the stock as thecylinder rotates, a series of compartments into which the stock is discharged from said dippers, said dippers and compartments coacting to advance the stock through the cylinder, and sprays directed across the path of the stock between its discharge from the dippers and return to the cylinder.

52. In a structure of the class described, the combination of a foraminated cylinder, a series of internal dippers adapted to elevate and discharge the stock as the cylindei rotates, a series of compartments into which the stock is discharged from said dippers,

said dippers and compartments coacting to advance the stock through the cyiinder, and 10 means for agitating the stock Within the compartments.

In testimony whereof, I have signed my name to this specification.

ANTON J. HAUG

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