CUT A~JD MILL FIs~RI ZER
of the Xnvention This invent.on rPlates to a machine for reducing sheets of wood pulp to c.iscrete fibers. Wads o~ such fibers are pleasingly white and are used, for example, as an absor-bent mate:rial in dispos~ble diapers, sanitary napkins and the iike.
Until recently, webs ur sheets of dry soft pulp wereused almost exclus.ively to make fibers. Use of haxd pulp is no~ becomin~ more common. A disk type fiberizer appara-tus, ~uch 2S the one described in U.S. Patent No. 3,538,551, particulated or fiberizecl s~ft wcod pulp efficiently ~nd with a satisfactory degree cf f~neness. The patented fiber-izer has a m~lli.plicit~ of pointed pins extending axially from one face of a disk that is rotated at high speed. The sheets of wood pulp are fed through a slot in the disk housin~ and into the pointed rotating pins which break off fragments of the pulp sheet and reduce the~l to fibrous particles as they are heing centrifuged radially outwardly from the centet of the disk. It has been dis~over.ed ~hat this type of fiberizer, althou~h very sat.isfactory for processing so~t pui~, has its pointed pins worn away a~ a higher than acceptable rate when hard pulp is being processed. However, it had the desirable property of separating the fibers from the so~t pulp sheet stock wilh a minimum of damage to the fibe.rs, that .is, it preserved the fi~er Filaments in rela-25 tively long lengths which is desirable when the fiber isdestined to be used in an absorbellt hatting. It has been found that a dil~eYent approach must be taken to achieve the desi.rable propel-ties when the feed stock is hard pulp.
Summary of -the_Invention The invention provides a wood pulp fiberizer including:
a housing comprising a generally circular wall and front and rear walls, respectively, enclosing opposi-te sides of -the circular wall, the front wall having a slot for feeding a sheet of wood pul.p into the housing axially of the circular wall, rota-table shaf-t means extending axially into said housing and a disk mounted to said shaft means for rota-tion ln said housing with one side of the di.sk facing the front wall and the o-ther side facing the rear wall, said slot extending chordally across the disk so tha-t said sheet is fed toward the disk offse-t from -the rotational axis of the disk, equiangularly spaced apart radially extending bars faste:ned to the disk on -the one side facing said front wall and rows of cutter prongs projecting axially from said bars toward the front wall of the housing, stationary cutter blades arranged above and below said slot inside of said housing, said blades projecting axially to proximity with but in noncontacting relation to said cutter prongs, said cutter prongs cooperating with said blades to particu-late a pulp sheet fed through said slot, a plurality of hammer members projecting radially from -the periphery of the disk and extending axially of the disk for orbiting wi-th the disk, a breaker segment arranged along at least a part of the orbital path of the hammer members, said segment having teeth projecting toward the path of the hammer members for cooperating therewith to further break the particles into fibers, the tips of said teeth lying on a nominally involute line adjacent said orbital path of the hammer members such tha-t the distance between said tips and said hammer members decreases in the rotational directi.on of the disk, and
screen means arranged along a par-t of the orbi-tal path of said hammer mernbers following said breaker segment in the direction of hammer rotation and through which fibers are propelled by said hamrner members for being withdrawn from the housing.
The fiberizer apparatus is distinguished by its ability to fiberize hard wood pulp without having to be taken out of service for maintenance at frequen-t intervals. It divides ha,d wood pulp into long discrete filaments or fibers while at the same time produces a minimum of short fibers or dust in the batting product. The fiberizer has elements in a single housing for chip-ping fiber particl.es from the end of a pulp sheet, reducing the particles at one stage subsequen-t to their being segregated from the sheet and then further milling the particles to reduce them to discrete fibers whereupon they are centrifuged through a screen for further reducing their compactness.
How the foregoing features are achieved will be evident in the more detailed description of a preferred embodiment of the new fiberizer which will now be set forth in reference to the draw-ings.
Description of the Drawings FIGURE 1 is a fron-t elevation view of the fiberizer with a portion of the front wall of its housing broken away -to show the interior thereof;
FIGURE 2 ls a section taken on the irregular line corre-sponding with 2-2 in FIGURE l;
FIGURE 3 is an axial view of a disk that carries cutting and mi.lling members and rotates in the housing of the fiberizer, said disk being shown isolated from the assembled fiberizer of -2 ~
FIGURES 1 and 2;
F`IGURE 4 is a side view of the disk in FIGURE 3 with a part broken away and sectioned;
FIGURE 5 is an enlarged view Or a section taken on a line corresponding with 5-5 in FIGURE l; and -2b-
3~7~3 E~IGURE 6 is a rear view of a portion of a pair of stationa.ry cutter blades which are shown in profi3.e in FIGURES 2 and 5.
Descrlption ~ t Referring to FIGURES 1 and 2, the fiberizer includes a housing comprised of a generally ci.rcular wall 10 that has a channel shaped cross-section and is closed on its sides by means of a fron.t wall ].1 and a rear wall 12. In FIGU~E 1, one may see that from a point where the lead line from the re~erence numeral 13 is applied to a clockwisa location wnere the lead line from :the numeral 14 is applied the radius o~ outer wall 10 of the housing increases so it has an involute shape. Also, from the lead line of nurneral 15 clockwise to approximately the lead line from numeral 16, the radius of outer wall 10 of the housing decreases so it has an involute shape. In the left r~gion of FIGURE 1, one may see that the housing has an output port 17 from which the fibers are evacuated or discharged.
As can be seen best .in FIGURE 2, the front wall 11 or the housing is provided with a slot 18 for feeding a sheet or web or dry hard pulp into the housing for processing. ~IGURE
1 shows that the slot 18 is a chord of the generally circular housing and that the chord i.s radiall~ displaced from -the center of the housing. FIGURE 2 shows some schematically represented guide plates 19 between which the.re is a gap 20 through wh.ich the shaet of hard wood pulp is fed thxough the slot into the housing along a plane coincident with that of the arrow 21. ~ pair of driven friction rollers 22 and 23 are used ror pushing the pulp sheet through the slot into the hous.ing. Roller 23 has a pinion 24 on its shaft which engages another pinion 25 on the shaft oE roller 22. The shaft of rollex 2~l has a sprocket 26 on it for heing driven with a chain 26' w~li.ch i..s shown fra~nentaIi.ly. In an actual embodiment, a pneumati.c cylind~r, no' shown, i.s provi.ded for pressing upper roller 22 down yieldingly to create the necessary force for driving pulp sheets of various thicknesses through the slot 1.8 (~
As shown in ~IGURE 2, a shaft 30 extends through an air intake opening 31 in the rear wall 12 of the housing. One of the bearing blocks 32, in which shaft 30 is journaled, i5 shown as being mounted on a base member 33. There are actually two bearing blocks but one has heen omitted from the drawing. A
screw 30' in wall 11 acts as a safety stop which precludes shaft 30 from ever shifting so much that rotating and stationary parts would collide. The shaft has a v-pulley 34 on it to facili~ate driving it rotationaliy with belts 35. As can be seen particularly well in FIGURE 2, the shaft has a hub 36 fastened to it and a rotor or disk assembly 37 is fastened to the hub for the disk to rotate in a plane that parallels the front 11 and rear 12 walls of the hou~ing. A circular brake plate 27 is fastened to a shaft 30 and it rotakes between brake linings 28 and ~9 which are forced toward each other to create friction on the plate for decelerating the high speed disk 37 to a stop when driving power is removed from pulley 34. The ~isk or rotor 37 i5 shown in isolakion from the hub 36 and in more detail in FIGURES 3 and 4 although it is partl~ visible in FIGURES 1 and 5 as well.
As can be seen in FIGURE 3~ the disk 37 is provided with holes 38, arranged in a circle, for permitting it to be fastened to the hub 36 with machine screws, not shown. The disk has a plurality of equiangularly spaced radially extending bars 39 fastened to the face 40 of the disk that is p~esented toward front wall 11 of the housing. Each of the bars 39 are secured to the front face 4~ of the disk wikh several cap screws 41. Because the bars are subjected to high centrifugal force, it is desirable to further secure them with keys, such as the one marked 42 which engages compl~men-tarily in keyways in the bars and the disk.
In the illustrative e~odiment, bars 39 have a row cf axially extendiny cutter prongs 43 formed on them. The prongs desir~bly have a square cross section and flat exposed ends. The bars, and, hence, the prongs are made of hardenecl skeel or other especiallv hard m~tal. As call ~e seen, the prongs in each bar conskitute a radially exkending row cf 7~
prongs 43. Since the bar and prongs rise above the face of the disk, they serve as vanes for centrifuging particles of pulp, that are broken away from the end of the sheet by the prongs, radially outwardly beyond the periphery of the disk which is a desirable characteri~tic for enhancing the .fiber communiting process.
Those skilled in the art will appreciate that axially extending prongs comparable ~.o the prongs 43 micJht be anchored by other means to the disk instead of being inte-gral with bars 39~ In any case, it would be desirable ~odistribute the prongs over the face of the disk in radially offset rows to achieve centrifuging action. Also, as in the pxeferred embodiment illustrated herein, the prongs in a radial row should have some space between them.
As shown in FIGUP~ 4, the heads of the cap screws 41 that secure the cutter pxong bars to the disk are exposed on the rear of the disk. In an actual embodiment, the heads of the cap screws are provided with a diametral hole, not visible, and a wire, not shown, is fed through all of the holes to limit the amount by which the cap screws could turn out if ~hey should become loosened during use of the apparatus.
A plurality of han~ler members 45 are anchored equian-gularly about the periphery of the disk 37. The hammer members, as shown in FIGURE 3, have dovetail bases 46 which fit into complementarily shaped slots in the periphery of disk 37 to assure that the hammer mem~ers will not be centri-fuyed out at the high rotational speed of the disk. The hammer members are secured against axial withdrawal from the dovetail slots by screws which pass through holes marked ~7 in FIGURE ~. The breaker hammers orbit at high peripheral velocity with disk 37 and abou~ its center.
As can be seen in FI~UP~E 5 especially well a~d in FIGURE 2, the cutcer prongs 43 on bars 39 project towards the end of the pulp sheet 21 that is being fed through slot 18 into the fiberizer. ~ pair of bar-like cutter blades 50 and 51 a:re held by screws to the front wall 11 of the housincJ. The cutter bars or blades 50 have teeth or serrations S~ on their faces that are presented toward the prongs 43 on the rotating cu-tter bars. There is a small gap 53 allowed to remain between the tips of the serrations 52 on the stationary cutter blades and the ends of the prongs 43 on the rotating cutter bars so there is no contact between the stationary serrations and rotatillg prongs. The stationary cutter blades 50 and 51 extend chordally above and below the chordally extending pulp sheet infeed slot 18. The rota-ting prongs and stationary serrated blade~
coact to reduce Eragments of pulp that are broken from the end of the pulp sheet.
As shown in FIGURE l, a breaker segment 55 having a circumferential array of teeth or serrations 56 is fastened in the top of the generally circular housing wall lO. The breaker segment 55 extends substantially from the location marked 15 in the rotational direction of the disk clockwise in FIGURE l to the approximate location marked 16. The breaker segment 55 extends over an arc of about 90 in this design. The brea~er segment has a width substantially equal to the distance between the front and rear walls ll and ~2 of the housing. The toothed breaker seg~ent 55 has an in-volute shape corresponding to that of the housing. In one region 57 there is a substantial radial distance between the faces of the hammer members 45 and the teeth or selrations in the breaker segment 55. Because of the involute shape, t.he kammers 45 ~et closer and closer to the serratlons of the b;Paker segment in the direction of rotation of the disk ~ut the hammers never contact the breaker teeth as is evident from incpection o FIGUP~ 1.
A metal band 60 constituting a screen is arranged in the fiberizer housiny substantially concen-tric to rotating disk 3,. As can be seen best in FIGURE 2, the screen has a plurality of holes 61 through which the segregated fibers are projected by the centrifugal force of the com~onents on disk 37 and under the influence o~ the fannin~ eF~ect they create. The screen band has sufficient width to extend from the front wall ll to the rear wall 12 o~ the fiberizer housing.
-The screen has several metal tubes 62 welded to it. As shown in FIGURE 2, bolts 63 extend through the metal tubes for anchoring the screen. In an actual embodiment, by way of example and not limitation, screen holes 61 have a diameter of 3/8 of an inch. In the illustrated embodimen-t, screen 60 subtends an arc of about 180. In FIGURE 1, one of the curved ends 64 of the screen is in conkact with the inside of outer wall 10 of the housiny~ As indicated earlier, housing 10 starts to t~Xe on an inv~lute shape where the lead line for the reference nu ~ral 13 is applied and this involute shape terminates where the lead line for reference numeral 14 is applied. This develops between screen 60 and housing wall 10 a region 65 ~.aving an increasingly large radial dimension that is in reality a fluff conducting channel that leads to exit port 17 through which the fluffed fibers are withdrawn. Screen 60 is effective to cause hreakup of any agglomerates of fibers that ~ass through its holes. Thus, the fiber fluEf comes out of the fiberizer in a highly hcmogeneous state insofar as its density is concerned.
It should be noted that screen 60 extends from its starting point 64 in the clockwise direction in FIGURE 1 to its other curved end 66 which abuts one end of the toothed breaker segment 55.
In operation, a sheet of hard wood pulp is driven through slot 1~ under the influence of rollers 2~ and 23.
The end of the pulp sheet encol~nters the rotating staggered and axially extending cutter prongs which break fragments of the pulp from the end of the sheet. The fragment~ are further divided by the coaction of the rapidly moving PrOngS
and the stationary serrated cutter blades 50 and 51. The material is centrifuged radially outwardly for being further broken down by the interaction of the rotating hammers 45 an~1 stationary breaker segment 5S which is in the nature of a milling action. The now Einely divided fibers are carried around and proiected through screen 60 ;nto involute channel 65 wh~re the fluffy material becomes more influenced by the suction provided at discharge port 17. The fluEfy I~aterial is then conclucted, by means, not shown, to a dispenser, not shown, which deposits measureA quantities of the material on a con~inuous baek.ing sheet that is used to form aiapers by methods well known in the art.
Although a ~referred embocliment of the invention has been described in detail, such clescription is intended to be illustrative rather than limiting, for the inv~ntion may be variously modified and is to be limited only by interpre~
tation of the claims which follow.