US1670097A - Cane-grinding mill - Google Patents

Description

6 Sheets-Sheet 1 D. R. BOWEN ET AL CANE GRINDING MILL Filed May 51, 1921 May 15, 1928.

E55. \2 ESE R2 EGERQ May 15, 1928. 1,670,097 D. R. BOWEN ET AL CANE GRINDING MILL Filed May 51, 1921 6 Sheets-Sheet 2 6 Sheets Sheec 5 Filed May 31, 1921 D. R. BOWEN ET AL CANE GRINDING MILL mmEERm 5 May 15, 1928.

EEwEN a um Q Q 83mm 25E mmEE R 55E R xQ wnuumw zu QME ERQ mg M0 33% E u Patented ay 15,1928.

DAVID 1%. Bowen, or Ansonrn,connnc'ricotr; as DARDIS, or nannsgounn nni) FRANKLIN BARREL; an, or new-Haven, CONNECTICUT, Ass'reNoRs-BY; mnsivn ASSIGNMENTS, T0 FAEEEIJ-BIRMINGEAM COMPANY, moenronn'rnn, tor ANSONIQ CONNECTICUT, a coeronarron or CONNECTICUT.

CANE-GRINDING? mm.

Application filed May 31,

This invention relates to cane grinding machinery of the type employed for the grinding of sugar cane. y, 1 In the past it has been common practice to grind sugar cane in a mill or installation-having a number of stands of juice expressing rolls arranged in groups I of three, each stand orjuic'e expressing migll having a toproll, a cane roll and a bagasse roll, all provided with annular grooves. Customarily these three-roll stands or mills are preceded by a preliminary crushing instrumentality, consisting, for example, of one or two sets of toothed crushing rolls arranged in pairs instead of in sets of three, as is the case with the juice expressing rolls. I

The function of such preliminary crushing instrumentality has been to place thecane in condition for more eflicicnt action of the three-roll stands or mills which follow. The preliminary crushing rolls receive the cane when the latter is in a .very thick, bulky mass, with the stalks arranged in various directions and overlapping each other; and as the stalks are of considerable size, havinga diameter say of tWo inches or more, the depth of the cane mass is considerable, The preliminary crushers reduce the thickncss of the mass and at the same time have a certain splitting and shredding action on' the stalks, openingthein up and separating the fibers thereof, and producing a thinner and fairly uniform mat of fiber which is in better condition for being subjected to the squeezing action of the threeroll mills for the extraction ofjuice than would be thecase if no preliminary crushing were effected.

Of. course, it will be understood that in crushing and shredding the cane stalks, the preliminary crusher or Crushers express a certain amount of juice from the cane. This, however, has in the pastbeen regarded primarily as an incident to the preliminary crushing function rather than as a desirable end in itself. The common practice has, been to place one or two pairs of preliminary crushing rolls in front of several three-roll mills. For example, in a fairly large installation designed to grind, somewhere from say twelve hundred to two thousand tons of cane in twenty-four hours,

1921. Serial no. 474,050.-

there have been one ortwo-pairs of prelirni-f j inary' crushing rol-ls. fo1;lowed by threeor feur three-roll juice expressing mills,v

One object of, the present invention is? to; increase the; 'efiiciency of machinery'of the general type referred toyin grindingsugan cane. J

Another object is to: vprovide an'increase; in the uice extraction,

.More specifically, our object isto incr ease the efiiciencyof the, mill as awhole by ob taining increased effectiveness of the-prelim:-' inary crushing nstrumen'tahty so that it does more an-d better work than in: the past,"

spl-ittingand shredding the cane stalks to a- I greater extent, producing therefrom athine' nor, more uniform mat,'and aug-menting the extraction by the preliminary crushing rolls, ;1 the effect of alli of which is: to enlarge: the

efiiciency of the mill, reducing the numberjof the three-roll juiceexpressing mills follow-. mg the erushers, which: it is necessary. -.to

employ, and improving the millini that respect also; by virtue of the fact thatv coacting, preliminary crushing rolls arrangecln pairs are much easier and less expensive to: set up, to adjust andqt'o keep in repair tham are theordiinary three-roll mills. By our:

improvements also, the juice extraction wit-hi.

a given :amount of roll surface may be: increased. i

More specifically, also, our invention has in View the feeding of the c'ane" into the mill in a. more. expeditious and unlform manner than heretoforeythe more complete shreds ding and disintegration of the stalks by the preliminary crushing" rolls, through the action of coacting rolls of certain pairs ro tating at different surface speeds, in a mill where two or more pairs of preliminary crushing rolls are employedg so that when the cane reaches the juiee,.ex.pressing mills'it,

is inthe best condition to be acted on thereby in an effective manner; and another object is to improve the relationor coordination between the preliminary} crushing lIlStIIP mentality. and the juice expressing instrumentality following the same. t

To these and other ends the: inventioneonsists in the novel features and combinations ofparts to claimedp-j be hereinafter described and 23 and-23, respectively. All of these rolls provements In the accompanying drawings:

-- Fig. 1.i s a diagrammatic side elevationzof.

grooves of the three-roll mill and crusher rolls; I 7 Fig. 3 is a top .planview; of the parts shown in Fig. 2, illustrating a portion of the gearing' for driving the rolls; and

Figs. t to 19" inclusive, show different modifications," as hereinafter more particularly described, these'views being in the nature of diagrammatic] side elevations and 'showing more particularly the various rolls employed in grinding the cane.

In the'inst allatin shown in Fig. 1, th 1'e,e pairs, 20, 21 and 22, of preliminarycrushing rolls are, employed inv front of four three:

roll mills, .23, 24, and 26,.respectively; The three-roll mills may be of the type' conis monly employed, or any preferred type, but preferably each consists of a top roll, a cane roll and a bagasse roll. In the case of the first three-roll mill23, the top rolhcane roll and bagasse roll are indicated at 23,

of the several three-roll mills are provided with annular; grooves, in the preferred form, the grooves of succeeding mills being some what-smaller than those of preceding mills, so that-the division of the cane and the extraction of the juice. are progressively conjtinued as the cane is carried through the several sets'of rolls. The grooving of the three-roll mills and the relative spacing of the three rolls of each mill may be as shown in Fig. 2

The mills 23, 24c, 25 from each other at appropriate distances, as in ordinaryjpractice, and conveyors 27, 28

and 29 may be interposed, as customary,

these conveyors being-ofany suitable type for carrying the fibers from the bagasse roll of one mill into the bite between the'top roll and cane roll of the following mill. Prefer be at the'same level, as customary. i

ably also, the several three-roll mills will all t Y pairs, 20, 21 and 22, of preliminary crushing rolls are provided with annular grooves, creating crushing ribs and they are also provided with teeth forhooking into the cane, formed by cutting generally longitudinal grooves in the roll surface to intersect the scribed with greater pllcation of Franklin transverse grooves. This kind of roll is departicularity in an ap- Farrel, Jr, Serial No. 445,527, and we sha'll', therefo re, not refer herein to its detail features,-except to say that the transversev shaped crushing ribs nary crushing rolls areshown at 20,, 21 and 22 in Fig. 2 and Fig. 3, and thatthe generally longitudinal, i. e., slightly oblique,

grooves are shown at 20 21 and 22 in Fig. In the particular fmrm n ow under discussion the ribs of the prelii'ninary crushing rolls of all threepairsareotthe same pitch, but-this is not a matter of importance as they may be of successively smaller pitch if desired of the rolls ofthe several pairs of prelimi- In the form shown in Figs. 1 to 3, the three pairs of preliminary crushing rolls are all '7 located at the same, or substantially the same, elevation, which is somewhat higher than that of the followingithree-roll mills. In practice the housings 20, 21 and 22,01

the respective pairs of crushing rolls may all be suitably secured on top of a raised framework 30,-standing in front of'the bed 31, on which the three-roll mills;r est, and having its upper surface, or in otherwords a bed for the crusher-s, substantially above thebed for the three-roll mills. An endless ferredftype; A similar conveyor 88 is in-o te'rposed between the crushers 21 and 22, and a third similar conveyor is interposed between the last crusher 22 and the first threeroll mill'23;

It will be observed that in the particular mill now under discussion, where the preliminary crushing rolls are located at the same level but somewhat higher than the following three-roll'mills, the rolls of each pair of.

have their shafts somewhat out of vertical alignment, the. shaft of the upper roll being disposedabove but somewhat to the rear ot the shaft ofthe lower roll, wherebythecane passing through and discharged by the two coacting rolls takes a rearward and downward direction. In other words, by this offsetting of the roll centers, the passage of the cane between the rolls is assisted by gravity and the upper roll may, if desired. overhang to a certain extent the lower end. of the adjacent conveyor so that the cane is discharged directly uponthe lower portion ofthe upper run of the conveyor, which can ries it into the bite of the next pair of rolls. While on the general similarity in relative location of p the two rolls in a pair of crusher rolls to the V crusher rolls between which the cane passes i and 26' may be spaced this point it ,may be well to note I the construction. more compact.

. asagna? a be employed for this purpose or,ifor exam.-

ple, an upwardly leading conveyor similar to thosc'shown in the drawings From: the last crusher rolls 22,.thecane passes onto the endless conveyor 34', which ispartially" over hung: by. the toproll" of pair 22, and which delivers the cane between the top roll and caneroll of the firstmilli 111L351]. of the conveyors 32, 33' and 34,. shown in Fig. 2,1 the upper run of the conveyor carriesthematerial upwardly and" rearwardly until it is above'theilevel" of th'ebiteof the following two rolls, and thereafter: it'carsries the material rearwardly' into such bite and downwardly to a=certainaextent Nevertheless, so faras the broad aspects of the present invention are'concernedgthe conveyor arrangement may be very considerably varied,vor in some cases-altogether omitted, as Willi'beseen from the following description.

For the' purpose of; increasing the effectivenessof the crzushingr'andl shredding rolls, the: rolls ofi one or more pairs are differentially, driven as between the two rolls of a pair so as toproduce-a'. friction motion on the can and thereby cause the stalks tobe split open and: shredded; This occurs as a result of'the" different surface speeds of the rolls atf the opposite sides-of thestalli: in the roll bite and by our invention this differential motion: is? produced: in: a; crushing instrumentality having two' or: more pairs of crushing rolls;iand' by preference'the upper rolls of some or' all of the-pairs'of crushing rolls are" driven at higher speeds than the corresponding lower rolls.

In the formshown in'Figs-r1to 3, the upper rolls of the pairs 20; 21. and 22"are all:

driven substantially fasterthan-the corresponding lower rolls and in this particular instance about ten per cent fasten thanthe correspondinglowen rolls. I-n'e this particu;- lar form' the upper roll of each: pair is of substantially the same diameter as the lower roll and all: of: the rolls of; the preliminary crushing instrumentality' are of approximately the same diameter; Consequently in: this case the upper rolls; of the" several pairs are driven: approximatelyten per cent faster than the corresponding lower rolls by gearing' which is so designed. as to accomplish: that purpose. In attaining this end*',' as shown more particularly in Figs. 2' and: 3,

the lower rolis of the pairs 20,221 andi22' are driven from a: suitable prime mover by shafts 3'5, 36 and 37 respectively, on which said rolls are mounted, saidi shafts: having" keyed thereto gears 38, 39' and 4.0 respec+x tivelyr at. one; side of the machines 'llh'ese geazrs: mesh withigears 451,.4123-3Hdi4i3' respectivelyieon' theshaft's-ofthe corresponding upper'rollsi; The gears4e1,&2;and43,.however,

have? a: smaller number of: teeth than'do; the

v gears 38 39" and 40,. this number being 'so chosen as to bring about. the drive of the upper." rolls at .a' speed" substantially tenz per cent faster than the corresponding lower rolls, as previously-stated. v It 'shouldz'be understood, however, that while the. upper roll of pair 20 is driven substantially tenv per cent faster than the lower roll? of, said' pair, the upper roll of pair. 21: will; havea somewhat higher actual speed because; in; the: form shown in Figs. 1 to 3, the: surface=speeds; of: the lower rolls of pairs: 20, 212 and? 22: will preferably be pro gressive'l-y increased-to a; certain extent, the lower roll of the fi'rst pair having, for exe ample, aspee'd of'thirty feet perininute, the lower' rollsof the intermediate pairhaving a surface speed of thirty-three feet per minute,

for example,v and the lower'roll' of: the third 2 pair having; for-example, a surface speed of thirty-six feet perminute. i This, however,

is only one 'exiample of the relative surface speeds which maybe employed}, In this same mill the rolls: of each three-roll stand will all have approximately the same speed,

those'of mill 23"being,,in. the case noted, say

twenty-five feet per minute, those of 'mill' 24: being say'twenty sevenand one-half feet per minute, those of'mill" 25 being say thirty feet per minute, and those of mill. 26 being say thirty-three feet per i minute; In practice the rolls of the juice expressing stands will usually. be somewhat larger thant-hose ofthe pairs of: erushers, but this isa feature which we have not deemed it necessary to: illustrate. If,'for example, all the rolls are seventyeightinches long, the preliminary crusher rolls may be say thirty-two inches in diameterfand the rolls of the succeeding threeroll" mills may be say thirty-four inches in. dian'iet'eixf .In such a mill the upper rolls of both the preliminary, Crushers and the three roll mills may be eguipped with the usual hydraulic pressure evices, which we have not deemed it necessary to illustrate. The pressure'exerteds by'each pair of preliminary crusher. rolls may be somewhere in theneighborhood of two'hundred and fifty tons, for-example", or the pressure may be successii vely increased: to a. certain extent in. the crusher rolls-'asrinaybe desired; and the four three-roll mil-1e23, 2a, 25 and 26, may exert pressures of say three hundred and seventyfive, four hundred, four; hundred and twenty-five, and four hundred and fifty tons, respectively;

While We have I aszhaving' teeth to hook i'nto'the cane to drag it along, such teeth being provided b the intersectionaofgenerally transverse an 7 gen-- illustrated the crusher rolls being era-11y longitudinal grooves, respectively, we do not desire to limit ourselves to a construction. in which rolls of this specific character are employed, as the roll surface maybe considerably changed in character 'without departing from the scope .of our invention or sacrificing the advantages thereof. In operation the machine shownin Figs. 1 to 3, acts substantially as follows:

Cane is fed in any suitable manner between the rolls of the first pair 20, of preliminary crusher rolls, and the upper'roll I v rotated substantially ten percent faster than the lower roll, a frictionmotion upon the cane'stalks is brought. about, the surface at one side of the stalk being moved considerably faster than the surface at'the opposite side "so that while the stalks are being compressed and crushed between the ribs of the rolls, the rolls beingsubjectedto high pressure, thehdiflerent surface speeds tend'to bring about a thorough tearing open and shredding of the cane. The mass of cane is considerably compacted and the in dividual stalks are torn apart, disintegrated and shredded so as to form a fairly uniform mat of fibers which is of considerably less depth than the body of cane passing to the 1 I rolls. This mat is discharged'directly upon the conveyor 32, which carries it' upward into the space between the rolls of the next pair, 21, which further reduce the-cane and carry on the action hereinbefore described; and from these rolls the conveyor 33 carries the cane mat to the third pair of crusher rolls, from which it is carried by the con veyorS i to the first mill. I

The action of the several pairs of crusher rolls as just described, causes a relatively considerable amount of juice to be expressed from the cane in the crusher instrumentality, this juice being collected in any customary manner; and the cane is very well conditioned for the subsequent act-ion of the juice expressing mills 23, 24, and 26. which in this case, due to the increased effectiveness of the crushers, may extract a smaller percentage of juice than wouldotherwisebe the case. These three-roll mills act in the customary manner but the cane is in better condition for juice extraction by them when it reaches them and in certain cases it may be found that the crushing instrumentality, if constructed and operated along the lines described, is so effective that the three-roll mills can advantageously be reduced in numher. It maybe found, therefore, that in an installationhaving crushers of the kind shown in Fig. v1, the mill as a whole will be highly efficient with only three stands of i juice expressing mills, or even a less number, instead of the four three-rollmills which we have illustrated in this particular case. V I

Referring now to the modified form of the individual rolls of a machine shown diagrammatically in Fig.4, it will be observed that the .three-roll-mills previously described, but the first pair 42, of preliminary crushing rolls is somewhat differently arranged, being located at a higher level than the second pair 43 and being .23, 24, 25 and26, are the same asin the case adapted to discharge the cane by gravity. di- 1 of crusher. rolls, the cane passes to the third pair 44, over a conveyor 45, substantially in the manner, previously described. i

In this case'also, the arrangement of thesecond pairof crusher rolls is somewhat different from that first described, in so far as the lowercrusher roll of the pair 43* is driven faster than'the upper one; but in this case as well as the first case the difference betweenthe surface speeds of the two vrolls of the pair is substantially ten percent.

In the form shown in Fig. 5, the first pair 2 46 of crusher rolls, and the second pair-47, are arranged at the same elevation and a con veyor' 48 carries the cane from the first pair to the second pair. These two pairs .arelos cated at a higher elevation than the third pair 49 andthe material passes'from' the second pair 47 to thethirdpair 4:9.by grave ity, and thereafter passes by gravity (over a suitable bed if desired) to the first threeroll mill 23. I i

In this case also, the relative speeds of the rolls of one pairare somewhat different than in the cases first described." In this particul'ar instance the upper roll of the first pair isdriven substantially five percent fast-p er than the corresponding lower roll; but the rolls of the second and'third pairs are driven at the same relative-speeds as between pair, as in the case first mentioned. I

In the form shown in Fig. 6, the relative locations of the diiferent'p'airs of crusher rolls are the same as in the form shown in Fig. 5, but in this case the rolls of the first pair 50 are driven at the same-speed, so that there is no differential motion in the first crusher, which acts to crush and compact the cane mass and to feed .it to the second pair of rolls without a differential motion. Also inthis case, the differential motion "in the seven and one-half percent faster than the bottom roll,- whereas the top roll of the third.

ea-lone? crusher 52 is driven fifteen percent; faster than" the corresponding: bottom rolh In the case'showniinvFig; 7,tthere. are no conveyors used lIl'COllIlGCtlOIl with the-crushthe bottom roll ofthe fiIStiPELlI' is drivenfivei percent faster thanits niateand thebottonr roll of: the third pair is; driven fiit'eenpercentz:

er rolls, oi which there are, as previously described, three. pa rs. The hrstpair feeds by-gravity to thesecond. pair and similarly the second pair. to. thethird pair and the third pair: to the first: three-roll'r-mill. In this case the top rolls of the several crusher pairs have successively increasing difierene tial motions, the top roll of the first pair being five percent faster than its mate, the

tive as the mat: is condensed" or compaete.d;.

and. as it is more and more thoroughly'sepa;-

rated into the individual fibers;: and: the

action. under discussion produces a fairly uniform, dense mat: of separated.fibers-upon.

which the following three-roll millscan not very effectively in extracting the remaining ju ce. V

In the form shown in. Fig. 8, there: are. likewise three pairs. of preliminary crusher rolls. In thisicase the arrangement of: the

rolls'is substantially the samezas that shown; inITig; 1, with interposed conveyorsz82, 3'3

and 34, like; those previously described, but

faster than its mate, while-the top: roll of the intermediate pair is; driven ten percent:

faster than its mate. r

It may. be assumed for purposes ofi description that in the form.shown;inFigs .v5 to 8 inclusive there are. four three roll. mills:

fol-lowing the crushers, asinthe case first described, althoughwe do note-limit ourselvesa to such an arrangement.

In the form shown in 9, the; rolls of the first pair of crushers are'driven-at: even speeds: and deliver the cane by, gravity tova;

lower second pair of'crushers, the. upper roill v of which is driven seven and; oneehalf per:-

cent faster than'the-l0wer; roll. 1' 'llhecrusheri rolls of the second pair deliver the-'canegto a;

conveyor similar to those previously; de scribed, which carries it to the'thirdpai r of crusher rolls, ofwhioh the upper roll is driven fifteen percent. faster than the lowerroll. From-thethird pairof, crusher rolls the cane;

is carried through the mill in the manner previously described. y

In the form shown in Fig; 10;, the: first crusher consists of a pair ofrolls, of which the. upper roll, is drivenfive percentct'asterv than the lower roll, and these rollsdeliver: the. came to: a conveyor which carries. it to the second pair of crusher rolls, which are driven at even speeds; and the second pair 4 of crusher rolls deliver the caneto. the

driven ateveirspeeds likewiserand from the third, pair of crusher rolls the cane passes; to the-first three-roll millvbygravity.

In theriorinishown in Fig. 11, the firstandj second. pairs of crusher rolls are driven at even speeds, there being aninterposed co;n-

third pair, the, individual rolls of which are: 7

veyor. The second" pair deliversthe; cane by gravityto the. third pair ot' which"- the'upper-roll? is-drivensten percent faster than the lower roll, and: the cane' is thereupon deliveredby gravity toithe first three-roll mill;

as in the case. illustrated in Fig. 10;

In. the iorin shown in Fig. 12,; therexare 85- four pairs. of. preliminary crusher rolls, which in this instance areall located atthd same; level, with interposed conveyors," sub also the upper. roll of each pair'is driven-- ten'percentfaster' than its mater. However,

of crusher rolls. are employed, and consequently we have shownonlythree three-roll ,mills: followingthe crushers in: this case,

stantially as shown in Fig. 1. "Inithis case in this case a greater: 'an-lountaof worlrisq done by the crushers than wherethree'pairs and efiicienti results might be obtained by-"an even smaller number of three-roll mills,-

Ins the form showni in Fig. 13, ther'e are four pairs of: preliminary crusher rolls, the

upper roll. oiithe firstlpair being-driven fivepercent: faster: than its mate,the upper rollof the second: pair' beingdriven seven and"- one-halfi percent: faster than its mate, theupper: roll of the; third pair beingdriven ten percent fasterv than its mate, and the upper roll of the fourthpair being" driven twelve:

and one-half percent faster than its mate;

It will be'seen, therefore, that in a crusher" havingat least four pairs of crusher rolls the differential motion is 1 progressively inc-reasedsithroughout the series.

Inthe'iorm shown in Fi gvlt, there are fours pairs-of preliminary crusherrolls and speeds but; imthe remaining crusher'roll s the differential motion .the rolls of the. first pair are drivenateven 1 15: is progressively ing- I creased, thertop; rollloi' the second pair be-' ingdriven ten percent faster than its mate;

the-top rollol thethird pair-being. driven: r

twelve and one-half percent faster: than its mate, and the top roil of. tlie fourth' pair be ng driven fifteen. percentifaster than its-' mate. In thiscase the cane passes by. gravity from: the first-pair: to the second pair, then to a conveyor, and thenby'gravity froni I the third pair tothe fourth pair, andby a conveyor to thevfirst three-roll'niill,ofwhiclr in this .case there are'thr'ee In the; forni ShOWHYlIIElfl}. 15, there are:

four; pairs oif-rorusher' rolls,.thefirst pair bee ingrdriven at even speeds. The first crusher rolls deliver the cane by gravity to the second pair, of which the top roll is driven ten percent faster than its mate. The cane then discharges onto a conveyor which carries it likewisefour pairs of preliminary crusher rolls. .The rolls of the first pair are driven ateven speeds.

them onto a conveyor which'carries it to the first pair are'driven at even speeds.

percent faster than its mate. 'roll of the thirdpair is driven twelve and rolls of the .second pair, theupper roll of the second pair. being driven at a surface speed ten percent faster than its mate; From the .rolls of-the second. pair the cane "discharges onto second conveyor which carries it to the rolls of the third pair, all of the first three pairs of rolls being arranged at the same elevation. From thethird pair of -,rolls the canedischarges by gravity into the'bite of the rolls of the fourth pair, In

this case the lower roll of the third crusher is driven twelve and one'half percent faster than its mate and the top roll of the fourth its mate.;- 1 I In the form shown in Fig. 17, there are crusher isdriven fifteen percent faster than two pairs of preliminary.crusher.- rolls ar-- ranged at thesame elevation, with an inter.-

posed conveyor 'andtwo pairs of following crusher, rolls arranged at the same elevation,

which is lower} than they elevationof the first two pairs, there being a gravity feed from the second pair to the third pair and a conveyor -feed from. the third pair to the fourth pain In this case the rollsofthe The upper rolllofthe second pair is driven ten one-half percent faster than its mate. -The upper rollof the fourth pair is driven fifteen percent faster than its mate. e In the form shown in Fig. 18, the first and the third pairs of crusher rolls are driven at even speeds and inthe second and fourth pairs-the top roll is driven ten percent faster. There is a gravity feed between the first and second pairs and between the third andfourth pairs, and also between the fourth pair and the first three-'roll'mill; but

there is aconveyorfeed between the second pair of crusher rolls and the third pair.

In Fig; l9,there arejthree pairs of pre liininary crushing rolls arranged at the same level, a fourth pair arranged at a lower level, and a first three-roll mill at a still lower level. Between the first and second pairs a conveyor arranged, as also be- The: cane discharges from The lower tween the second pair andthe third pair;

but the feed between the third pair and the a fourth pair is by gravity, as is also the feed from the fourth pair-to the first three-roll mill. In this case the rolls of the first-pair and those of the third pair are driven at" even speeds, likewise those of the fourth pair, but the rolls of the second-pair have a differential motion, the upper roll ofthcsaid pair being driven tenpercent faster than its mate.

Itwill be understood that in all of these forms relative speeds are given merely by Way of example, and that various other airrangements may beadopted' without depart ing from the scope of the invention as set forth in the claims; I I i It will-be observed that in the mill shown in Fig. 3,- the crusher rolls of the second pair have a less number of longitudinal grooves than do the rolls of the first pair, and similarly the rolls of the third pair have a less number ofiongitudinal grooves than do the rolls'of' the second pair, We consider this arrangement of advantage, owing: to the fact that the longitudinal grooving provides teeth which are, more necessary when the.

cane is first actedupon than when it has been somewhat reduced and compacted. As the cane comes from the field, a considerable number of teeth are necessary tohook into it crusher rolls to the second pair, but the secoiid pair of crusher rolls does not'necd such a largenumber ofxteeth, and similarly in the duced.

tion as distinguished from the hooking act on. 'By providing'the successive pairs of and to carryit along from the first pair of ion third pair the number can be further re- 1 It will be understood also that the longitudinal grooves interrupt the rolls cir-- 'cuinferentially and reduce thecrushin'g ac crusher rolls with successively fewer circumfer'ential interruptions it will be seen that the crusher surface available, for forc cibly squeezing the cane in the valleys of the transverse or annular grooves and on the suinmits'of the annular ribs is successively increased, which is a feature of considerable advantage. While it is inerito 'ious, how,-

ever, it is not essential in all cases and it may be assumed that in the other forms shown and described the hooking surface of successive-crusher rolls may or may not be successively decreased'in proportion as the 7 rib squeezing surface is successively increased,

Various changes in these and other-re spects will occur to thoseskilled in the art as being within the scope of our inventive conception as expressed in the following claims.

It will be understood, for example, that I in a preliminary'crusher having the relative speeds'referred to in connection with Fig. 14:, the several -pairs of'crusher rolls may all hammer he locatedtat the same elevation, as shown in Fig. 12, with interposed conveyors. So, also, crusher rolls having the same or approximately the same relatlve speeds referred to in connection with Fig. .6, may all be located at thesame level, with interposed conveyors, as shown in Fig. 2. Obviously, also,: many other combinations may be made, the forms shown being merely by V havingthe relative speeds of the crusher rolls of one pair different from the :relative speeds of the individual rolls of another pair, as where, for example, the rolls of one pair have the same surface speedy-Whereas the rolls of another pair have different speeds relatively to each other or Where-two different pairs of crusher rolls produce a friction action on the cane, the'difi'erence in surface speed in one pair being different from that in another pair. While we have not shown these and related features embodied in a mill having only two pairs of crusher rolls, norhave we shown a mill with only two pairs of Crushers designed to pro duce a certain friction motion in :the first pair and an increased friction motion in the second pair, it will be obvious to those skillediin the art that such features areapplicable to preliminary crushers having more than one pair of rolls, and are not confined to installations wherein there are more than two pairs of preliminary. crusher rolls. In Fig. 7, for example, the firstpair of crusher rollsmight be omitted; and inFig. ,6, for example, the thirdpair of crusher rolls might be omitted and provision might be made forcarrying the shreddedcanejdirect-ly fromthe second pair 'to'the firs't three-roll mill.

While in all of the cases illustrated, the so-called friction motion on the cane in the bite of a pair of rolls is produced by using on the roll shafts gears having a'dissi'mil-ar number of teeth, the rolls being ofsulostantially the same diameter, it will of course be readily understood that the difference in the surface speed'of the two rolls may be obtained in other ways; and it isobvious also that wherethetwo coacting rolls areofdifferent diameters the revolutions per minute of the respective roll shafts mayor may not be the same, although, for producing the friction motion there will be in all cases an appreciable difference of'surface speed.

According to our invention the speed difference should, if practicable, amount to at least five per cent, while according to the practice which we regard as the best, it Will One of these as-y approximate tenpericent, as :in the forms of our. :invention herein illustrated and described. In the practice of our invention, it]. substantial speed difference is produced intentionallyand by preference through the use of dissimilar gear teething :in connection 7 with cooperating rolls 0f the same diameter so as to bring about a marked increase in the ishredding action, the cooperating arolls, furthermore, \being preferably circumferentially grooved and provided Withinterruptions inf-the ribs between the grooves so as s to createteeth .as described. It will, be un derstood, however, that in some cases the speed diflerence may ;be obtained by differ? ence of diameter of the crusher rolls, and

that various other modifications may be made without departure from the scope of the appended claims.

What we claim is:

crusher having vmore than two pairs of co said pairs having the individualv rolls driven at different speeds, the differencebetween an In a cane grinding imill, a preliminary the surface speeds'of the rolls, .of one pai r being greater than the difference between the surface speeds of a-notl'ier pair dillerentially driven rolls.

2.- In a cane grinding mill a preliminary crusher having more than two-pairs o'f =coacting ribbed crushing rolls arranged so that the cane passes successively between the bites of the -several pairs, the individual rolls of at least one .pair having di-fierent surface speeds to produce a friction action on the cane and thereby-increase -the ish-redding thereof, and the individual rolls of at least two other pairs likewise ha-vingxdifferent surface speeds to ;produce a friction motion :on the cane by those pairs of rolls, the difference in the surface speeds of the individual rolls of one pair being greater than the difference between the surface speeds of the individual rolls of another pair.

.I no

3. In a' canegrinding mill, a preliminary crusher having niore than two pairs of coacting ribbed crushing rolls arrangedso ,that the cane passes successively between the bites of the several pairs, the individual rolls of at-least one pair having different surface speeds to produce a friction action on the cane and thereby increase the shredding thereof, :and the individual rolls of at least two other pairs like-wise having diiler cut surface speeds to produce a friction motion on the cane by those pairs of rolls,'the

difference in the surface speeds of the ind i-.

vidual rolls of one pair being greater than the difl'erence between the surface speeds of the individual rolls of a preceding pair.

4. A preliminary crusher for cane grinding mills having a plurality of grooved crusher rolls arranged in pairs and means for driving said rolls'so as to produce a pro' gressively increasingfriction action on "the cane as it passes through the series.

A preliminary crusher for cane grinding mills having more than one pair of grooved cane crushing rolls, said pairs arranged in tandem and the relation between the surface speeds of the individual rolls of one pair being different from therelation between the surface speeds of the individual rolls of another pair andth'e rolls of a-suc I ceeding pair having a greater-surface speedthan-the corresponding rolls of a'preced ing pair.

'6. A preliminary crusher for cane mills having more than one'pair of crusher rolls, said pairs arranged in tandem, and the rolls of a following pair having a greater difference of surface speed as between themselves than in the case of apreceding pair-and having agreater actual surface speed than thecorrespondlng rolls of a preceding P2111;

7. A preliminary crusher for cane mills having more thanone pair of crusher rolls,

said pairs arranged in tandem, and the rolls of a following pair having a difference of surface speed as betweenthemselves,the individual rolls of apreceding pair having approximately the same surfacejspeedsp 8. Apreliminary crusher for cane grinding mills having more than three pairs of toothed crusher rollsi arranged in tandem, certain of said rolls having sucl relative surfacespeeds asto produce a progressively increasing friction motion on the cane as the latter passes through the machine.

9. A preliminary crusher'for cane grinding mills having more than three pairs of toothed crusher rolls arranged intandem, certain ofsaid rolls having such relative surface'spee'ds as to produce a progressively increasing friction motion on the cane as the latter passes through the machine, the rolls ofthe first pairhaving substantially and havinggreater crushing surfaces than the rolls of said other pair. H

'11. In a cane grinding mill, at least three pairs of preliminary crushing rolls arranged in tandem, the individual rolls of at least two pairs being driven at different surface speeds, and the difference ofsurface speed being diflterent in the two pairs. a

-12. A cane grinding mill comprising 'a preliminary crusher having more than one;

pair of'longitudinally and circumferentially grooved crusher rolls, the rolls ofa following pair of crusher rolls having a'greater differenceofsurface speed as between them-' selves thanin the caseof a preceding pair. 13. A cane grinding mill comprising);

preliminary crusher having more than one pair of longitudinally and transversely grooved'crusher rolls, the rolls of a follow ing pair of crusher rolls having a greater difference of surface speed as between them selves than in the case of a preceding pair, 'the longitudinal grooves of the rolls of said pairs being decreased. innumber toward the discharge end of the crusher.

14. A cane grinding mill comprising.

preliminary crusher, having more than two pairs of crusher rolls arranged in tandem and constructed andarranged to produce "an increasing friction action on the cane due to different roll speeds in the individual rolls of the several pairs as the .cane passes through the machine.

15. A preliminary crusher for cane grinding mills having more than one pair of grooved cane crusher rolls, said pairs: being arranged intandem and the relation between the surface speeds ofthe individualrolls of one pair being different from the relation between the surface speeds of the' individual rolls of another pair.

16. A preliminary crusher for; cane grinding mills having two pairs of cane crushing rolls,'said pairs being arranged-in tandem,

and means for driving said rolls, the;relationbetween the surface speeds of the individual rolls of one pairbeing different from'the relation between'the surface speeds of the individual rolls of another pair, there being a greater difference between the surface "speeds of two of the correspondingv rolls of, said pairs than between the other rolls of said pairs. 1 p

17. A cane grinding mill having more than two sets of circumferential'ly grooved crusher rolls in tandemconstructed and arranged to produce an increasing friction action on the cane due to different roll speeds in the individual rolls of the several sets as the cane passesth'rough the mill.

In witness whereof, we have-hereunto set our hands.

' DAVID R. BOWEN.

JOHN M. DARDIS. FRANKLIN FARREL, JR.

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