US2329773A - Vibrating screen - Google Patents

Description

Sept. 21, 1943. R. A. LEAHY 2,329,773

VIBRATING SCREEN Filed May s1, 1941 2 sheets-sheet 1 Ma/4m E mf/y,

INVENTOR ATTORNEY Sept. 21, 1943. R. A. EAHY 2,329,773

` VIBRATING ssEEN 'l Vme@ may s1, 1941 2- sheets-sheet 2 INVENTOR ATTORN EY Patented Sept. 21, 1943 UNITED STATES `=`PATENT vlz'lz'IClI-:-

` 2,329,773 viBnATiNG SCREEN Richard A.,Leahy,`rlilong Beach, Calif. Application May s1, 1941, seriaI No. 396,011 A volatils. (C1. 20e-310i This invention pertains to improvements in the art of screening granular or finely divided materials and is particularly directed to improvements in the construction of vibrating screens.

Generally stated, the invention pertains to vibrating screens in which a foraminousfmember such asa sheetof punchedI metal or a strip of wire mesh or screen cloth is held'within a frame, and yvibration is then imparted to the ioraminous member. The material to be screened,=separated or graded-is passed over tne screen, the vibration of the screening surface suitably separating the material during its passage over the screen.

Heretoiore, screening devices of this general character' have been devised. In v'most cases, .the

vibrating force is applied to the entire frame which supports the screen cloth. y In accordance with therpresent invention, the vibrating-iorce is applied to the screen cloth alone, thereby'more eiectively utilizing energy. Moreover, vinfaccord-y ance with the present invention, complete me#- chancal control oi intensity anfd frequency oi the impact vibration is made possible, vthereby permitting the apparatus to be readily adapted to the separation or treatment of various matemanner so as to produce a forward movementof A the particles of material being separated on the screening surface or cloth, this orwardmovement making it possible to decrease the angle or' inclination of the screen and thereby permit the Vscreen to be used in those locations which do not have available the amount o1" head room or vertical height required by prior screening` devices.

*Generally stated, the invention contemplates-a screen construction in which the screening rnedim issuer-,cned between the endl membe'rs of a stationary frame and employs anassembly beneath the screen, ,thisassembly including resilient longitudinalfmembers, 'the' 'entire vassemblyploe- 25 rials diering in physical properties. Novel` ing pressed against the lower `surface `fof .the screen, the pliant end portions of the resilient members being deected downwardly. A vibrator rod is attached to the assembly,lthe vibratorbeingfeonnecte'dto a follower arm `in sliding .con. f

tactV with a driven cam. The camandfollower are so arranged that a positive 'impact is periodically deliveredy through the vibrator/rod to the assembly beneath'the screen cloth,i.the. resutant forces including a forward element tending to move the m'aterialalong the screen suriace. A iiywheel is preferably employed 'on'. the driven cam shaft for the purposeof-A employing its inertia mstead oi' the dead-weight of theparts formerly required to concentrate impact; vibra.- tionstransmitted to vibratory screens. f

An object koi` the present invention, therefore, is to disclosel and provide a vibratoryrscreenof improved construction. Y i' Another object is to provide a vibratory'screen in which the vibrations are applied to andfdistributed over the vibrating screen in a nomical and eiiicient matter. f

` A further object! is to provide means whereby greater liie is imparted 7 to a'scre`eriing medium and means v*whereby Athe screeningmedium may be` readily replaced. i vAgainy an obj vctv or the inventionis to disclose and provide a vibration imparting unitof novel construction, such unit being `characterizedbyl low i'riction losses,` long life and theY utilization of inertia yoi arotating ywheel. i i' Other objects, advantages," adaptations and modifications of the invention lwill become apparent to those skilled in the'art Vfrom the following description of an exemplaryform or" the invention. f i

In the appended drawings: I vjk Fig. 'l is a plan View of an exemplary formof the present invention.A '1- Fig. 2 is a longitudinal section taken along the planen-II ofFig. 1. f' i I Fig. is a transverse Section planeI III-*III of Fig. 1. Q Fig. lis an enlarged transverse section of V'the vibrator unit. I 'f AFig. 5 is an enlarged longitudinal section 'of the vibrator unit. 'i

Figs. 6, 7 and 8 are enlarged views, partlydiagrammatic, showing the relationship of the cam and cam follower of the vibrator unit at'diierent positions.

In the drawings, v'a relatively rigid-frame is taken' along the shown formed from longitudinally extending side more ecol Various means for supporting this frame lin a desired inclined position may be used, but such means are not shown. The side and end rails may be made either of .channel iron, angle iron or the like. The said rails may be built up somewhat as indicated at and 6 .in Fig. 3.

One of the end rails may be slotted to receive a bar 8 having a foraminous member, screen cloth or ottieni-screening medium attached thereto. Screen clothxisuindicated fin the drawings at 9. The other end of lthe frame may be provided with tensioning means adapted to grasp the opposite end of the screening medium and place the same in tension longitudinally of the frame. .Forexf ample, the screening medium Sl may be provided with a bar lll adapted to be engaged' by the yoke ends Il of bolts I2 extending throughsuitable apertures in the end rail 3 and attached thereto by means of nuts i3. In this manner the entire screening. surfacev may be placed under uniform longitudinal tension-.within the frame and may beiremovedtherefrom forreplacement. M Beneath the screening medium @there is placed a relatively light subframe or assembly which, intheformshown in4 the drawings, comprises a resilient longitudinalmember I5 carrying e plurality. of. transverse membersil, .,l'l, lvand i9. These ,transverse,members i5T-I9 may be prof vided .with resilient andgnarrowgbearing strips -alongtheir upperfsurfacesnfor contact with the bottom of the lscreening, mediuin. Rubber compositions,v leather or wood maybe used for these bearing strips carried, by the tops of the transverse. membersJi-flg. K Y A Y 4 It may benoted et this. time,,th et theupper surfacesof .the transverse stippeitiiiemembers 16.-,-19 woccupy 42l plane, o r planes slightly above a plane passing through the end portions of the foraminous member 9. See Eig. `2.) lfuitablyg suppqrted beneath. the..Stttt9i1a -FY `frame, es .fori exemple by ineens .O f herleeft 2i and 22, is a drive shafft23 journaled in bearings 24. ,.'Ihedrive shaft 23 A may becarriedlwithin .a .tubular Y housingn25ffconnectel to a` centrally disposed Split @911.53.13 .Whh may 5.1.50 CQUFQP? suitable bearings for the shaft" 2 3, Within `this `Split .Oil-tight. housing 25.91 033227.15 {nouned A.upon theshait... The 2.7.11eY, be Provided with ,one camere inclined ,fetes 2,8 arid. 23.

Withiiitheiieiieipetheireis Diveted ee et 3i] a follower armjcarrying afollower 3 2A at Io ne end. .,Rreferably ktheern-.Ilfof the Vfollower arm elis hifureeted, Athe,lfeiiewer..ttbeiiie held between. the spaced. erid .pettieiis etthe.. erm 3| .upon e Suitable piani Stutbeitee so niet 'the follower 32 may rotate. The follower isl'vshown in the drawings as a polygonalfelernent and may .b eeither hexeeeneieaeeteeonel iii fem- TAH octagonal form is illustrated'sinefthis ha's'been foundwto )be (then preferred form. The follower rests upon the cam 21. Thevfollowe'r'arm 3| is eieeprevitiedwitii. eV vitfetei red. 35 eiifetellif connected to the arm alsV at 31. The vibrator fred ttiexteiids. upwertiiy tifreiete Port iii the the housing 26, such port'beiifg''shQwnin'Fig` 5 .es rieyidefmitheri .tipeterifiiiie piiieeeetiri '3B adapted to slidably extend into a( sleeveu3'9 carried ey.. the. .tempered et The esta )eii'd "ef the .vibretei .reti 3.@ .ieteiiteeteei iii eiiyeiitetie perte the )longitudinally extending resiliitfs''bassembly member 5. .Y f s '.lheiieiieine ztfmeylteipievified ,Wittfeeitt atie .aieialeluee- ..A. f1i\theei 4 l .liievj be .matted trainee nd efltii'e `Shelft"?3"-'Tife shaft 23 may be driiin'i'n butin the drawings the flywheel il is shown pro* vided with an integral pulley 42 adapted to receive a V-shaped belt making a driving connection with a .motor not shown.

It will loe noted that the subassernbly iis not connected to the stationary frame of the device in any manner .and the only support for the -subassembly is the vibrator rod 36, and such `subassembly. and screening mediumin contact therewithis therefore free to .vibrate most effectively. By adjusting the locli'ng nuts between the vibrator rod 36 and the resilient longitudinally extending member I5, the desired portions of the subassembly may be raised above a plane extending through the end portions or ends of the screening medium 9. The screen cloth or other screening mediumwill therefore exert a downward Ypressure upon the subassembly and the pliant end portions of the resiilent longitudinal member, l 5 whieltmey be. previdedwith .tapered ends), may be .defieeted-dewnwerdix b xpressiire en the.trensveree-memberal te 1 9 exerted. by component .fereesef thelengitudinel tension 0f thesCreen Jcloth between the ends of the stationaryframe'..

.i Byreferrinate. Fissfl .'1 1emi .8 .the operation Yof the eem end, pelyeoneleiloweriwiil .become apparent..- The` cem NMrQtetes inthe direction ,oftheerrow ,seas .teeeusetbe rising feee28 and zato strike en. ineiiriedfaee. of, lthe follower 32,. a `.solici ,blow-` By referring.. tarife.. ,6l fer eX: emule. itriviii beeeeii tilettheleweafeee 5.0 of the follower .itis slidinselengftiie .substantially ,ey- .iindrieeieurfeee 5| .et the eem. 21.-, T he ierversi face 52. efttie felieitei 32.ie. et Substantially, lthe rseme .etieleee theaiisieof the. fate .28 ,Wiiieii is eprireeeiiitieim felitii'ei.-` Tile @ansie a: .Should .be @n ll? mgl? @QW/C?? @P9191 ,99 nd 07, Sie.' rendite unen, the weigerte? `feeeeifii tiiejeeivsentii. ieilewer @Lilli/Then .eeteeeiiei felltltier is employed3 the; angleuznshouldnbe lalciout 45", Whenan hexagonalfollower is` employed, the Vangle a: 'should Abe about '6`Q. xpre'ssd "differenuy, yit fmay pe stated that itii'e fe'iigle fft'rie face 28 islsupplemeitarywfto the internal angle y between 'adjacentf'faces fthe follower '32. The "falce`2'8 the 'faef'l sli'ofuld 'rneetiix :substan tial Contact.`4 Thei lfigh't'ff the face 2'8`sh61d fnt 'xc'e'dfth'e radius `o`f fa 'circle ,inscribed a cross ctinoflth folloiive'r,32 and preferably should b'e between 15% fi'd 50%"f the A*raiii'isff sihin'sribed circle i'ndi'cfaftedt.,

After the fece 2a1'strikes the inclined Afate 52 of the follower '32,V`th`e fo'llow'er32 will pivo't u'pn 'the stud boit 3'3 'es shown innig., 7 "and `similitaneously with s'uch pivoting iiioveinent 'the fllower will rise, causing the follower arin `3`| to pivot and causing the vibratr ro'd 3`6 to inve upwardly until the face '52 of the follower begins t'o slide upon the cam 'surface '54 of th'ef'cam (21 as shown in Fig. 8. i'

Y Theimpact of-the rising-fac`e '28 foffthe cam against the face 52 of the follower is transmitted instantaneouslyto the lmaterial upon the screen medium ..9,. .the impact. throwingthe particles of .the material upwardly.. ,and..,forward1y. with. .a forceproportionel te tbemesseschthe particles. Automatically these impact forces cause the ceereeet.eriwevieet-nertieieateitiie tep, ,er the :.eeimittineltiie iieiter,

Vward movement of material on the screen takes place, followed by a short quiescent period just before the next impact of the two new faces of the succeeding cam tooth and the follower. The time interval for the rise of the screen surfacek appears to be less than of the cycle of operations.

The various movements described herein are steadied, localizedl and made more uniform by the inertia of the rapidly revolving flywheel 4I. The force of impact between the faces 28 and 51 is controlled to some extent by the speed of the flywheel, and the force of these blows appears to be proportional to the peripheral velocity of the cam. The frequency (expressed as impacts per minute) is the product of the number of cam teeth or rising faces by R. P. M. of the drive shaft 23 and flywheel 4l. This applied energy is concentrated more on the screening'medium, and is dissipated less in the screen frame and the external supporting structure. This greatly reduces the weight and strength of the structure necessary for supporting the screening apparatus which is generally situated in the upper and less stable part of the plant.

When the apparatus is employed in the screening of materials which have a tendency to adhere to the screen surface due to viscosity (as in damp, clayey material or vdrilling muds) or due to their weight or size, the the intensity of the impact may be increased by reducing thel number of cam teeth and increasing the peripheral velocity of the cam. When the apparatus is employed in screening fine, dry material or line materials in a very large portion of liquid, the intensity of the impacts may be reduced and their frequency increased by reducing the velocity of the cam and increasing the number of cam teeth.

It will be noted that the telescopic connectionincluded in the conduit section 38 and the sleeve 21 forms a labyrinth which prevents the entrance of foreign matter into the oil filled housing. Flaps of flexible material indicated at 60 may be connected to the side rails 5 and 6 and overlie the longitudinal edge portions of the screening medium 9 so 'as to prevent material being screened from spilling off the sides of the screen.

Although in the drawing a single longitudinal member l5 has been shown, it is to be understood that the subassembly may comprise a plurality of longitudinally extending resilient members l5 connected together by a plurality of transversely extending contact members.` In most screens, the vibrator rod 36 is attached to about the midpoint of the subassembly, although on larger screens more than one vibratorrod may be used, each vibrator rod being actuated by its separate follower and cam. When two vibrators are employed they should be synchronized and both vibrator rods connected to a transverse vibrator arm which then is attached to one or more longitudinally extending resillient members. Moreover, two lywheels instead of one may be employed, one flywheel being carried by each end of the shaft 23.

I claim:

1. In a vibrating screen construction, the combination of: a stationary frame; a flexible screen medium provided with end bars; slots in said frame adapted to receive one of said end bars; tensioning means cooperating with the other end ,bar for placing ,the screen medium under` tension within the frame; a lightweightsubassembly includin'g. am longitudinally extending resilient `member provided with longitudinally tapered ends and a, plurality of longitudinally spaced,

transverselyextendingv screen supporting members valong said longitudinal resilient member, said transverse member being adapted to contact with the lower surface of the screening medium; means positioned beneath said subassembly for imparting upward impulses to the subassembly, said means including a follower arm.l pivoted to a stationary support at oneend and provided with a polygonalfollower carried by the movable end of said arm, a vibrator rod attached to said arm and to said subassembly and Aadapted to place said transversely extending screen supporting members in pressure contact with the screen medium, adrivencam shaft provided with aY flywheel and a cam having an impact face substantially parallel to a face ofthe follower at the instant of impact and means for driving said cam shaft in a direction to cause impactimpulses lto produce an upward and forward motion of material on the screen medium supported by the subassembly.

2. In a vibrating screen construction, the combination of: a stationary frame; a flexible screen medium stretched in longitudinal tension between end members of said frame; a lightweight subassembly including a longitudinally extend- Aing resilient member provided with longitudinally tapered ends and a plurality of transversely extending screen supporting vmembers attached to the longitudinal member in spaced relation and adapted to contact with the lower surface of the screen medium; means positioned beneath said subassemblyfor imparting upward impulses to the subassembly, said means including a follower arm pivoted to a stationary support at one a face of the follower at the instant of impact and means for driving said cam shaft in a direction toA cause impact impulses to produce an upward and forward motion of material on the screen medium supported by'the subassembly.

3. In a vibrating screen constructionJ the combination of: a stationary frame; a flexible screen medium provided with end bars; slots in said frame adapted to receive one of said end bars; tensioning means cooperating with the other end bar for placing the screen medium under tension Within the frame; a lightweight subassembly including a longitudinally extending resilient member provided with longitudinally tapered ends and a plurality of spaced, transversely extending screen supporting members adapted to contact with the lower surface of the screen medium; means positioned beneath said subassembly for imparting upward impulses to the subassembly, said means including a follower arm pivoted to a stationary support at one end and provided with a polygonal follower carried by the movable end of said arm, a vibrator rod attached to said arm and to said subassembly and adapted to place said transversely extending screen, supporting members in pressure contact with the screen medium, a driven cam shaft pro- 'vided with a camfliaving'an impact face-substantially parallel toiajfacebf the fllewerat the'in- 'stan'toi impactand means for driving s aidcam shaft in a'direction to Vcause impactinpulsesto produce an upward and'forwardmdtin VVtif-inaf- 'ter'al on 'the screen mediumsupport'ed :bythe subassembly. y y d l 4, Ina vibrating scieenfcoristruction,V the conibination of: a stationary frame; aflelrible'screeh @5 *areas attached tosa-id means'and to 4said sub-assembly Nv'hereby said'screen medium lis uniformlyvibratedjand said vibrations are transmitted to d fad/jacent the ends of said screen medium fthfijou'ghthe :tapered ehdprtions ofthe longiftudinal "sub-assembly member,

6: 71u a'vibrating screen construction, the com- "bi'riatioho: -a stationary frame; a lexible screen medium lstretched in longitudinal *tensin be- Qirdmedium stretched in longitudinal tension between -tween end members of saidirarnefa lightweight subassembly including a longitudinallyextending resilient Amember provided with downwardly deflectable ends and 'ajplurality*ofspacecl, trans'- versely extending screen supporting members adapted to VContact with the"A lowersurfc'efof the screen medium; means pcisitiojneclberne'ath said subassembly `for imparting j'upward ljiniptlises to the subassernbly,` saidnieans` includingi afollower 'arm pivoted to a stationary 'support at oneend 'andprovided lwith a plygonarfollower carried "bythe'movableend of said arm, a' vibrator -r'od attached to saidarm and to said suba'ssernbly'and "adapted to place 'said `transversely extending screen supporting membeisiin pressure contact with the screen medium, a driven cam shaftprovided with a cam having lanjimpact face `substantiallyparallel to 4'aface of thejfollowerat `the instant of impact and mea'nsvfor drivingfsa'i'd l cam shaft vin `a` direction to cause impact-irnpulses to produce anupward an'djfoiward motion of lmaterial on the screen'medium supported by the subas'sembly. i y Y d l 5. Ina vibrating screenY constructiomthe commedium removably lattached'kby its longitudinal end portions to the frame, tensioning'meanset one end of said frame ahdcoopeating'with "said screen medium for placing thescieen undertension within the framefalght weight suba's'se'nibly including a longitudinally :extending resilient member provided with longitudinally tapered ends and a plurality of transverselyeiitendng spaced screen supporting members "adapted to contactl with the lower surface of the v,'sc'fe'iifrrie- 45dv `being.maintained convex by upwardly :directed pressure applied through 'said supporting inembers and tapered longitudinal member, saidsubA means positioned beneathv saidfsublassembly" for 'imparting sharp upward impulses fto the'v'sib- V"end lineinblersof sai'd 4frame; -a light weightfsubassembly vincluding Va longitudinally extending resiiient member 'provided with longitudinally :tapered-ends, and -a plurality of longitudinally "-3-i5spac'd transversely extending screen supporting `nre'nibers'- along said longitudinal member and at- 4tachedthereto, said transverse members being J"arlamted to contactwith the lower surface ofthe vscreen medium; meansforf holding said sub-asio" smblyjin pressure contact witlrthe lower surface fot-the screen medium to'impart aconvex upper surface to said'screen medium; said sub-assenb bly `being unconnectedrto saidfrarne and end 1`nembers thereoi^ and means, for 'imparting up- '7'125`Ward impulses-'tothe sub-assemblyfwhereby sub- `strntially uniform vibrationis transmitted toall portions of the screen medium through said resiient sub-assembly member.

7. `YInjafvir'irating screen construction, the comobinatin otra stationary frame; a flexible screen i diu'mrprovded with end bars, slots in said r`fratrie adapted to receive one of said end'bars; tensioning means cooperating with the other end bar for placing the screen medium under tension binann of; a stationary frame, a flexible"sheen-a5i'niifiame; a iighrweight sub-assmblyincludv40 beneath the screen; means for holdingsaid s'ubassembly in 'pressure contact with the-lowersurace of said screen medium to impart 'a convex "ccntourto the upper surface of said Ascreen mefdium; `and means positioned beneath thesubassembly for imparting upwardly impulses there- 'to whereby vibrations may be uniformlydistributed to sad screen medium through the resilient,longitudinally extending member, said sub-assembly being unconnected to said frame assembly being unconnected to saidfra'me; and A50 'and end bars ol said screen medium.

RICHARD A. `LEAHYl

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