CA1161291A - Segmental pulpstone - Google Patents

Abstract

ABSTRACT

An improved segmental type pulpstone has circumferentially faced spiral grooves in the outer abrading surface thereof for collecting and allowing deeper penetration and circulation of shower water to wash away ground pulp, reduce plugging of the pores, cool and prevent overheating of the abrasive segments the attaching bolts and the resulting spalling and/or loosening of the abrasive segments from the supporting core.

Description

2~

SEGMENTAL PULPSTONE

BACKGROUND OF THE I!~VE~TION
Field of the invention:
The invention relates to segmental type pulpstones for grinding wood pulp wherein bonded abrasive segments are 5 secured to a central core by bolts with a different rate of thermal exDansion and which in use are normally flooded with shower water to flush around pulp from the pores, to prevent overheatinq, spallinq and looseninq of the se~ments from the core.
10 D~SCRIPTION OF T~E PRIOR ART
To this day many segmental type abrasive p~lpstones are constructed by attachinq bonded abrasive segments to both cylindrical metal and concrete cores with metal bolts or studs liXe fastener means of various forms. However, 15 problems such as overheating, breaka~e, spalling, and loosening of the segments have not been entirely overcome and arise when the metal bolts fastened to the core and segments ~ecome overheated and expand at a qreater rate than the abrasive segments and core.
The problem of overheating usually res~lts when the larqe volume of water fails to wash awav the ground pulp and allows small particles thereof to enter and event~ally pluq the pores in the abrading surface. ~ence, the large volume of shower water normally directed a~ainst the abradinq 25 surface cannot penetrate, ahsorb, and remove excess heat qenerated durin~ grinding press~re contact between the loqs of pulpwood forced aaainst the abradina surface. U.S.
Patents 2,745,226, 2,76~,286, 2,887,276 and ~,erman Offenlequnqsschrift 2,853,716 disclose a partial solution to 30 the problem of overheatinq with res~ect to segmented ~ulpstones wherein abradina segments are bolted in spaced relationship to a hollow cylindrical shell or core. I~ater

3 1 2 b~ ~1 ~ 'ater is s~DPlied to the interior of the hollow core having radial passa~es in the wall or bolts for directinq ~ater under pressure to and between the non-abradiny side surfaces of ad~acent segments~ ~owever, with respect to pulpstones of the 5 type disclosed in U.S. Patent 2,421,~85, the cooling water cannot pass readily from the interior of the solid concrete core to the abrading seqments, and must rely solely on the exterior shower water to wash away pulp and prevent overheating of the ~ulpstone.
The applicant's invention is directed to an improved seqmental pulpstone provided with deep circumferentially spaced qrooves that collect and increase the penetration and effectiveness of the shower water Hence, the operatin~
temperature of the abrasive segments and attaching bolts is 15 more uniformly controlled and maintained at a safe levelO
In U.S. Patents 1,132,258 and 3,132r815 there are disclosed Dulpstones provlded with either A continuous helical or circumferentially spaced shallow grooves or furrows extending across the abrading surface at an anqle to 20 the axis in addition to the shallower and more conventional grindin~q, sharpeninq or burr pattern. However, the furrows or ~rooves which have a maximum depth of about 1 n (~5mm) are provided for the s~ecific ~urpose of quickly collectinq and disposing of the wood fibers to prevent rearindinq thereof.
25 Further, the pulpstones are not made up of abrasive segments attached to a core by bolts or studs with a different rate of thermal expansion and affected by overheatinq of the abrasive se~ments attached thereto.
SUMMARY OF THE INVE~TION
.
A rotatable segmental grooved p~lpstone comprising preformed bonded abrasive segments and attached bolts with a different rate of thermal expansion assembled about and attached to a core adapted for mounting the p~lpstone on a drive spindle assem~ly for rotation. Each bolt has a 35 convoluted or thread-like end portion inserted or threaded into and fastened to an inner non-abradinq portion of an abrasive seqment and an op~osite end portion extendinq 2~

therefrom adapted for attachment to the core. A plurality of relatively deep circumferentially spaced qrooves extend radially into and continuously across the outer abrading Dortion of the pulpstone and each abrasive segment at an 5 angle to the rotational axis and opposite radial sides of the segment.
In rotational use the deep grooves collect and circulate the cooler shower water therealong into and through the porous abrading and non-abrading portions of the seqment~
10 about the bolts. The cooler shower water flushes wood fibers out the grooves, is centrifugally forced outwardly and thereby removes particles of ground pulp from the pores at the abrading surface. ~ence, the shower water circulates more freely to carry the generated heat away and thereby 15 prevents overheating of the abrasive segments, the attaching bolts, and the resulting loosening spaliinq and/or breaking of the abrasive seaments.
BRIEF nESCRIP~ION OF TE~E DRAWI~GS
Figure 1 is a front view of a grooved se~mental 20 pulpstone constructed and qrooved accordinq to the invention~
Fisure 2 is an end view of the ~rooved segmental pulpstone of Figure 1.
Figure 3 is an enlarged partial view of the grooved 25 abradinq surface ad~acent one end of the pulpstone showing the interfitting arranqement, configuration construction of the abrasive segments, with a pair of diagonal grooves and location of the attaching bolts.
Figures 4 and 5 are sectional views through a 30 portion of the pulpstone taken on line 4-4 and 5-5 respectively of Figure 3 and showing double grooved abrasive seqrnents secured to a reinforced solid core by bolts threadlv attached to the segments and embedded in the core.
Piqure ~ is a plan view of a modified abrasive 35 seqment, ~rovided with but one groove in the abrading portion and suitable for constructinq seqmental pulpstone with fewer qrooves.

2~

Fiaure 7 is a partial sectional vie~ sh~wing a sinqle qroove abrasive seament of the ;nvention sec~red to a hollow cylindrical core by nuts and bol~s threaded to the abrasive seg~ent and m~dified to extend through apertures in the ~a~l of the core; and 9 ~ i~ure 8 is ~ plan view of assembled center and end seaments with three diaoonal grooves for constr~cting another emb~diment of the pulpst~ne.
_CRIPTïON OF THE PREPERRED MBODIMEt~T~
Shown in the drawinas is an impr~ved peripherally grooved rotatable segmental pulpstone 10 of the invention for grinding wood pulp. The pulpstone 10 com~rises a cy~indrical center or cQre 12 includinQ a central bore 14 c~nstructed and a~apted about its rotational axi~ and ODpo5ite ends for 15 attachment to any suitable conventional drive spindle in the well known manner. Assembled aboutv s~aced or separated by striDs of known joint filler material 16 and secured by metal bolts 18 of known design to the outex peripheral or circumferential surface of the c~re ~re interchangable, 20 reversible and interfitting six-side~3 or hexa~onal center ~nd, five sided ~r penta~onal outer or end bonded abrasive segments 20 and 22 respectively.
The strips of joint filler material 16 may be of any suitable flexible deformable yp~e but is preferably the 25 cellular vulcanizable rubber material c~ntainin~ qranules of c~rk diselosed in ~.S, Patent 2,0~4,771 Depending on the apPlicati~n and tvpe of pulpstone, the attaching metal bolts 18 may be one of the known 3~ conventional ty~es disclosed in ~S. Patents 2,421,885, 2,745,22~ and ~,769,286. Each bolt 18 has a threaded or thread-like convoluted head or end Dortion 18a and either an op~osite end p~rtion 1Bb with axially spaced annular ~DrtionS
and intervenin~ ar~ves ad~?ted t~ b~ embedded in a sol id 35 concrete core as shown in Fi~ure 4 or as shown in ~iaure 7, an o~p~site threade~ end pcrtion l~c including a nut and washer adapted for attachmen~ to a hollow cvlindrical core ~2' .

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Additionally, each of the abrasive seqments 20 and 22 has at least one relatively deep groove 20b extendin~
radially into and across the outer interrupted abrading portion 20c thereofl at a predetermined angle and position 5 relative to a side thereof that aliqns it with the qroove of the adjacent segment, and a similar groove provided in the filler strip 16 there between. ~ence, collectively, the grooved abrasive segments 20 and 22 and qrooved filler striDs 16 therebetween provide the pulpstone 10 with a plurality of 10 relativelv longer continuous grooves 20b and intervenin~
abrading portions 20c circumferentially spaced around and extending the entire axial length or wiath of the interrupted abadin~ portion of the pulpstone and each of the abrasive segments therein at an angle to the rotational axis of the 15 ~ulpstone and logs of pulpwood engaged thereby. Typically, the useable and reducible abrading portion of a trued pulpstone 10 is no less than 2-9/16" (6.5 cm). However, each abrasive segment 20 and 22 has an initial radial depth before truing of about 5-1/4" (13.3 cm) and an abrading portion of 20 about 3" (7.6 cm) extending inwardly to ends of the threaded bolt heads 18a and holes 20a, defining the outermost circumferential boundry B of the inner non-abradinq portion and depth of the holes 20a and threads 18a of about 2-1/4"
(5.7 cm).
Although the initial depth of the abradinq portion mav and will vary durin~ use, the grooves 20b are of sufficient de~th to place the bottoms thereof within and no more than 1 1/4" (3.17 cm) from the outermost circumferential boundary B defining the ends of the bolt heads 18a.
Referring to Fiaures 1-5, the ~roove 2nb, may be of any suitable conventional shape. However, they are preferrably V-shape to prevent entrapment and enhance easy removal or release of the wood pulp fibers therefrom.
Typically, each molded groove 20b has an initial outwardly 3~ flared or curved elonqated entrance about 3/4" (19 mm) wide, opposite tapered sîdes extendinq fro~ convex entrance surfaces of about 1/2" (12.7 mm) radius to a concave bottom of about 3/16" (4.7 mm) wide and 3/32" (2.38 mm) radius 2~

located about 9/16" to 1-1/16" (1~42 to 2.7 cm) from the boundry B between the abradinq and non-abrading portions and an initial maximum depth of about 2 to 2-1/2" 15.07 to 6.34 cm). ~ence, reqardless of wearing away and reduction of the 5 abrading portion, the bottom of the ~rooves 20b are permanently located relatively close to the boundry B and heads 18a of the bolts 18 and allow cooler shower water to circulate through the pores, thereof, and carrv heat away to prevent overheating.
Referring to ~igures 3 and 4, typically each inner or center hexagonal abrasive segment 20 of a completed and trued grooved pulpstone 10 approximately fi7" (170.~ cm~
diameter by 69" (175.26 cm~ axial length is symetrical about a central radial plane extendinq from the axis of the 15 PulPstone. It also has a maximum axial length of about 10.8 (27.46cm) at the central radial plane of symetry, a circumferential width of about 9.5" (24.1 cm) and a radial thickness of about 5" (120 7 cm) at the oentral radial plane.
Preferably each seq~ent 20 comprises a spaced pair 20 of sli~htly tapered V-shape diaqonal qrooves 20b, adjoining interrupted diaqonal abradin~ portions 20C, a Pair of slightly tapering opposite radial sides 20d including upper edqes thereof, of equal lenqth, extendinq parallel to each other and to the central radial plane and two pairs of 25 sliqhtly tapering diagonally opposite sides 20e and 20f with upper edges of equal len~th extending parallel to each other and at substantially the same angle from the central radial plane of symetry. Each of the grooves 20b e~tends parallel to the other in diaqonally opposite dir~ctions across the 30 segment from a center point, corner, or apex, situated at each opposite end of the segment and intersection of a diaqonal side 20e, a diaqonal side 20f with the central radial plane to a diagonally opposite side point corner or aPex at the intersection of a radial side 20d and diaqonal 35 side 20e.
With the exceDtion of having one less side, a sliqhlv different shape and length and a straight f~at end surface 20q, the outer or end abrasive segments 22 at 3 ~2~

opposite sides or ends of the nulpstone 10 are otherwise substantially identical in constr~ction size and shape to the corres~ondinq ~ortions of the center seqments 20 described above. The end seqments 22 are molded in the same molds ~sed 5 to mold the center segment but which have been modified by plugaing one end of the cavity with an insert adapted to form a single straight end 2ng instead of the usual intersecting dia~onal sides 20e and 20f. ~ence, a segment 22 molded therein will have a spaced vair of diaqonal parralel grooves 10 20b, an interveninq abrading portion 20c and a pair of opposite radial sides 20d, only one diagonal side 20e and one dia~onal side 20f at one end and a straight surface 209 at the opposite end thereof. Nevertheless r the segments 22 are also interchan~eable, reversible and interfit with either end 15 of a center segment 20 to align the grooves 20b of adjacent segments 20 and 22. As shown the segments 20 and 22 and joint filler material 16 therebetween are assembled in a stagqered pattern whereby each seqment and circumferential row of seg~ents incl~dinq the ioint material therebetween are 20 displaced one half the circumfe~ential width of the segments in the adjacent row. Thus, there is provided an interfittin~
locking and supportinq arrangement between seqments and ~oint material interrupted by intervening abradinq portions.
As shown in Figures 1 and 3 the stagqered pattern 25 places each pair of diagonal opposite sides 20e and 20f of a center segment 20 spaced by ~oint filler material 16 op~osite the same diagonal sides 20e and 20f of diagonallv spaced adiacent center segments 20 and end segments 22.
Referring to Fiaures ~ and 7, the pulpstone may be 30 constructed of similar hexagonal center segments 30 and pentagonal segments 32 (not shown) but simply indicated in Figure 6 by a dash line and straiaht end 30q, that are identical in every other respect to the segments 20 and 22 except that each has but a single diagonal ~roove 30b and 35 abrading ~ortions 30c of equal size. Each groove 30b is preerably wider than but extends s~bstantially the same depth and distance relative to the boundry B' and ends of the bolt heads 18a as does the groove 20h. The sinqle groove 30b extends diaaonally from substantiallv the mid-~oint of one diaaonally opposite side 30e, through the center or mid point of the maximum length and circumferential width of the segment 30 located on the radial plane to substantially the S mid-point of the op~osite diagonal si~e 3ne. Thus, the center segments 30 and end segments 32 molded in the same mold and manner taught above would likewise be interchanaeable, reversible and interfit ~ith the sides of ad~acent sea~ents sufficientlv to align the qrooves 3nb of 10 ad~acent interfitting segments 30 and 32.
Preferrably the sinale groove 30b has an outwardly flared or curved entrance of about 1-1/2" (3.8 cm) wide and opposite tapered sides tapering or convergina toward each other from a convex surface of about 1/2" (1.27 cm) radius to 15 a concave bottom of about 3/8" t9.5 mm) wide and 3/16" (4.76 mm) radius located at the boundrv B' hetween the outer abrading and inner non-abrading portions of the seqments and pulpstone constructed therewith.
A se~mental pulpstone constructed with sin~le 20 diaaonal qroove preformed abrasive seaments 30 and 32 and attached bolts 18 will have relat:ively lonq continuous wide dia~onal qrooves 30b and interveninq abrading portion 30c of equal width eaually spaced about the circumference of the pulpstone. In contrast the pulpstone ln constructed with 25 double diagonal groove preformed abrasive seqments 20, 22 and attachea bolts 18 has relatively lona contin~ous narrower diaaonal qrooves 20b of equal width unequally spaced about the circumference by intervening abrading portions 20c of two unequal widths. Thus, the pulpstone 10 has ecually spaced 30 pairs of qrooves 20b with about 50~ of the abrading portions 20c of equal width therebetween equally spacefl about the circumference ~ the remaining abradinq portion 20c of equal but different width.
Further, the preformed grooved abrasive seqments 35 20, 22, 30 and 32 need not be of the specific hexo~onal and pentaqonal shape shown but of any suitable reversible interchanaeable polyqonal shape se~ments symetrieal about radial and circumferential planes normal to each other and ~ ~6~2~

provided with one more diagonal ~r~7es as tau~ht abover For example, the shape of the abrasive segments may be square or rectangular or ~rianoularO It is als~ conceivahle to construct a pulpstone bY assemblin~ qro~ved and/or plain S groovless segmen~s of different size, asymetrical and svmetrical shapes in a particular sequence and interfitting patterns different from that disclosed herein. Alternatively, a pulpstone constructed with conventional plain gr~veless segments may have the di3gonal ~ro~ves 20b and/or 30b cut into 10 the abradin~ portion thereof with a diamond, boron nitride or tungsten carbide qrinding wheel or ~utting tool.
Aside from the circumferentiallv s~aced grooves 20b and 30b in the abrading ~urface to which the invention is directed, the ~ulpst~ne 10 may be of the type and constructed 15 in substantially the same mann~r as those disclosed in U.S.
patents 2,421,8B5 and 3,227~611 with solid reinforced concrete cores and 2,745,226 and 2,769,286 with metal cylinder or drum-type c~res.

Briefly, a pulpstone 10 with a solid reinforced concrete core i~ c~nstructed on and ~*ith the nid of a known transportable appartus or fixture comprising a moveable car ~r carriage, a hDrizontal base-plate with a vertical 25 centerin~ arb~r ~n the car, a top plate, circular c~am~s, radial clamps, axial ~lamps and ga~in~ means. A cage~ e annul~r reinforcinq unit R of smaller diameter and axial length than the pulpstone comprisinq a plurality of concentrically, radially, and axially sDaced steel 30 reinforcinq rings and spacer elements is placed on the base plate and clamped concenti~allv ab~ut the center arbor.
A first circular outer row of end se~ments 22 or 32, then ~ne or m~re inner rows o~ center seqment~ 20 or 30, another circular outer row of end seqments 22 or 32 and the 35 joint filler strip 16 are assembl~d and clamped ~oth ~ircumferen i~lly and axially to~ether con~entr;cally around the reinforcing unit R and the center arbor. The assem~led 2~1~

cylinder of seqments with ioint filler strips compressed therebetween, the reinforcing unit X and the fixture on the movable car are moved into a kiln to cure and vulcanize the ioint filler strips 16 and the adjoining abrasive segments 5 toqether into a cylindrical unit.
Following curing, the assembly is moved out of the kiln, allowed to cool, and a two Dart drum or tubular molding arbor is ~ixed concentrically within the reinforcin~ unit R
to form the central bore 14. The cavitv between the outer 10 cylinder of seqments and the molding arbor is filled with concrete and allowed to cure sufficiently to remove it from the fixture, remove the molding arbor and form the end mountin~ surfaces of the core. The grooved pulpstone is then mounted on the drive spindle, rotated, and the pheripheral 1~ abradin~ surface thereof is trued concentric to the axis of rotation and the strip 16 cut out to extend the grooves 20b or 30b continuously throuqh the joint filler strips 16 and segments.
In contrast a pulpstone with a metal cylinder or 20 drum core is constructed by ~rovidin~ a metal cylinder of sufficient diameter, circumference, axial lenqth wall thickness with the required number and ~attern of holes necessary to receive the end portion 18c of the bolts and attach the prescribed number`and arrangement of segments to 25 the core.
The preformed qrooved abrasive seqments with attaching bolts are then attached to the metal cylinder with or without loint filler strip 16 between the segments and/or the core and se~ments by insertina the ends 18c through the 30 holes provided in the cylinder wall. A washer and nut is then threaded thereon and tightened sufficiently to moderately tension the bolts 18 and retain the segments aaainst the cylinder and when provided to compress the joint filler strip therebetween. A pulpstone assembly without, 35 need not but a pulpstone with filler strips 16 is placed in an oven or kiln to cure and vulcanize the strip to the segments. Either way, the grooved pulpstone is then mounted on a drive spindle, rotated, and the abrading surface trued 1 1612~D

concentric to the axis of rotation and the strips cut out to extend the groove 20b or 30b through the joint iller strips and segments-.
The heads 18a are preferably about 2-1/4" (5.7 cm) 5 in axial lenqth and provide with a 1-3/8" (35 mm) diameter x .5" (12.7 mm) pitch rolled thread. The adjacent opposite end portions 18b and 18c may ~ary in length and diameter.
However, the opposite end 18b is preferably about 8" (15.2 cm) long with axially spaced annular beveled portions about 10 1-1/8" (2.85 cm) in diameter by 3/4" tl9 mm) wide and intervening reduced portions about 5/8~ (15.8 mm) in diameter by 3/4" (19 mm) wide.
Dependinq on the wall thickness of the drum-like core 12' the length of opposite end portion 18c will vary.
15 Typically, the opposite end portion is about 5~ (12.7 cm) long, 5/8" (15.8mm) in diameter and has a 5/8" (15.8 mm) x 11 pitch threaded end of about 1-1/4" (3.2 cm~ in length.
In both cases the bolts 18 are each formed of cold rolled steel bar or rod about 1-1/8" l2.85 cm) in diameter by 20 about 7-1/4" or 8-1/4" (18.4 or 21 cm) lonq. One end portion of rod or bar is inserted between roll thread formin~ dies to displace the metal and form the threads and grooves of head portion 18a and the other machined to Eorm the opposite end portions 18b or 18c.
The abrasive se~ments are preferrably molded of a suitable vitrified bonded abrasive mixture and vitrified or fired in the known kiln and manner. The abrasive which may be of any suitable known type and arit size is preferably aluminum oxide or silicon carbide of from 24 to 100 grit 30 size. Depending on size and shape, each segment 20 and 22 has at least one or more and preferrably four spaced threaded holes 20a adapted for receivin~ the threaded portions 18a of the bolts la. The threaded bores 20a which may extend radially 1-1/2" to 2~1/2" (3.8-6.4 cm) into the inner 35 nonabrading portion of the seqment are preferably molded to a depth of about 2-1/4" (5.7 cm), centrally located and spaced substantially e~ual diagonal distances from the center of the seqment and hence, equal distances from both a central longitudinal radial plane and a central normal plane thereof perpendic~lar to each other~ Preferably, the distance of the hole 20a from the central radial and central normal planes are about 1-5/8" (4.1cm) and about 2-1/4" (5.7cm) 5 respectively. The bolts 18 are secured to the segments 20 and 22 preferably by filling each threaded hole 20a with a suitable known cement comprising for example a mixture of liquid phenolic resin and filler of fine abrasive or flint particles. The cememt is allowed time to penetrate into and 10 seal the pores in the ad~oining area to provide a strong impervious waterproof joint between the stud and adioining portion of the segment.
Excess cement is then poured out the threaded holes 20a and the heads 18a dipped into or brushed with additional 15 cement are screwed into the threaded abrasive holes 20 and moderately tightened to about 40 ft pounds of torque to prevent straininq or stressinq of the abrasive segments. The segment is then placed in an oven to cure the resin or cement and permanently fix the bolts head 18a to the segment which 20 after curin~ is ready to be assembled to construct the pulpstone 10 in the well known nnanner.
Another embodiment of the invention is shown Fig. 8 comprising a reversible interfit:ting and interchangeable bonded abrasive center segment 40 and end segments 42 of 25 polyqonal or hexagonal and pentagonal shape for constructing a qrooved se~mental pulpstone. The se~ments 40 and 42 each comvrises threaded bores 40a for heads l~a of bolts 18, a combination of three s~aced diagonal grooves 40b, interrupted abradinq surface 40c, opposite radial sides 40d and 30 diagonallv opPosite sides 40e and 40f. The combination of diaqonal ~rooves 40b comprises a single long central qroove extending diagonallv between the midpoint of opposite diagonal sides 40e through substantially the exact center of the segment and two shorter diaaonal arooves extending 35 substantially parallel to the central ~roove and in diagonally opposite direction from the center of each of the opposite ends to dia~onally opposite corners of the segment 40.

~ ~612~1 Each of the diaqonal grooves 40b are of substantially the same confiauration and dePth as the other groove 20b and 30b. They may be of the same but preferably of sliqhtly smaller width than grooves 20b.
Alternatively the combination of three grooves 40b may extend through the entire aiagonal axial length of the seqment as do the double grooves 20b and single groove 30b which may likewise be made shorter and to extend any part of the axial length of the segment as do the grooves 40b shown 10 in Figure 8.
Further, it is also conceivable to extend only one or two of the three grooves 40b completely across the axial length of the segment and leave one or two shorter whereby the pulpstone would have both lonq continuous and 15 discontinuous diagonal grooves.
As taught above a five sided pentagonal end segment 42 shown similar to end segment 22 but with three diagonal grooves 40b may be molded in the same mold as segment 40.
The exception is that an insert is placed at one end to the 20 mold to prevent formation of, al~er, and essentially cut off one end of the seqment 40 to form an end segment 42 with a straight flat end surface 409 and three grooves 40b.
An experimental grooved segmental pulpstone constructed according to the invention with double grooved ~5 bonded 60 grit size silicon carbide abrasive seaments and a reinforced concrete core has been tested under actual pulp grinding conditions. The experimental pulpstone was mounted on a conventional pocket type grinder wherein logs of pulp wood arranqed lengthwise were diametrically forced against 30 and around by the rotatinq interrupted diagonally qrooved abrading surface of the pulpstone. Positioned at various places about the pulpstone were the usual number of conventional shower or spray nozzle assemblies directing cool sho~er water against and flooding the qrooved abrading 35 surface therewith.
~ esults of the test conducted over a substantially long period of time reveal that there were no occurences of overheating, spalling, looseninq, breaXing and ~ ~L 6 ~

reDlacement or repair of anY ~art or seqment thereof. The ~ality of pulpwood fibers was as good and in some cases better than that produced with comparable plain groovless pulpstone~ Particles of pulpwood pressed into and tending to pluq the pores of the abrading surface were more quickly 5 removed by the centrifugally forced shower water and prevented the build up of a blanket of wood pulp on the abradin~ surface and the resultin~ overhea.ing and spalling of the se~ments.
The rotatinq spiral or inclined grooves caused an 10 increase in the velocity of the shower water and wood fibers collecting therein to be propelled and auickly removed therefrom, prevented pluggin~ of the pores, allowed penetration and circulation of the shower water through adiacent areas and removed the heat generated at the abradin~
15 sur~ace. Also, observed was that the inclined abrading Dortions interrupted by the ~rooves tended to lift, in a shear-like fashion, longer fibers from the log due to the fact they cross at an angle to and proqressively enqage only a small portion of longitudinal surface of the lo~ at any one 20 time. Also, the pulpstone appeared to be freer cuttin~r maintained at a more uniform lower temperature and took less power to rotate and produce pulp.
As many embodiment of the invention are possible it is to be understood that the invention includes all 25 modifications embodiments and equivalents thereof fallinq within the scope of the appended claims.

Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A grooved segmental pulpstone rotatable about a central axis thereof comprising:
a core, a plurality of bonded abrasive segments of interfitting interchangeable reversible shape and predetermined size with reducible outer abrading portions and surfaces and adjoining inner non-abrading portions and surfaces extending circumferentially about and attached to the core and providing the pulpstone with adjoining reducible outer abrading and inner non-abrading portions and surfaces, attaching means with a greater rate of thermal expansion than the segments fixed to and extending from the non-abrading portions of the abrasive segments and into the core for securing the segments to the core, a plurality of grooves circumferentially spaced about and interrupting the reducible outer abrading portion and surface, extending inwardly a predetermined depth into the reducible outer interrupted abrading portion to bottoms thereof situated at predetermined fixed distances no greater than 1-1/4" (3.17 cm) from and adjacent a circumferential boundary between the outer abrading and inner non-abrading portions defined by ends of the attaching means, whereby during rotation and production of fibrous pulp the grooves collect, convey and allow cooling liquid normally showering and flooding the grooved outer abrading surface along through the grooves to wash out the pulp, penetrate into pores and circulate through adjoining porous areas and thereby more effectively cool the outer abrading portion and thus prevent overheating of the attaching means and resultant spalling, loosening, and breakage of the segments.

2. A grooved segmental pulpstone according to claim 1 wherein the grooves extend longitudinally at an angle to a direction of rotation and central axis of the pulpstone and wherein each abrasive segment comprises:
at least one groove extending diagonally in the reducible outer abrading portion, between one end and an opposite end of the segment.

3. A grooved segmental pulpstone according to claim 2 wherein each of the segments further comprise:
at least one bore of predetermined depth in the inner non-abrading portion adapted for receiving an end portion of the attaching means.

4. A grooved segmental pulpstone according to claim 3 wherein the attaching means comprises:
at least one metal bolt having an end portion extending into and fixed within the bore in the non-abrading portion of each segment and an opposite end portion extending from the end portion and beyond the non-abrading portion into and fixed to the core.

5. A grooved segmental pulpstone according to claim 4 wherein the bore in the inner non-abrading portion is a threaded bore and the bolt has a threaded end portion threaded into and fixed within the threaded bore.

6. A grooved segmental pulpstone according to claim 5 wherein each of the abrasive segments further comprises:
a pair of grooves extending diagonally through the reducible abrading portion, between one end and an opposite end of the segment.

7. A grooved segmental pulpstone according to claim 6 further comprising:
a plurality of circular rows of the grooved abrasive segments of reversible, interfitting interchangeable polygonal shape arranged about the core with joints between adjacent segments staggered relative to the joints between segments of an adjacent circular row of segments whereby the diagonal grooves in the segments of adjacent circular rows are aligned with each other and extend across at least a portion of each segment of the pulpstone.

8. A grooved segmental pulpstone according to claim 7 wherein the core comprises:
a reinforced solid concrete core adapted for mounting on a drive spindle and wherein the opposite end portion of the metal bolts have one or more axially spaced groove and are embedded in the concrete core.

9. A grooved segmental pulpstone according to claim 7 wherein the core comprises:
a preformed hollow metal cylinder including a wall adapted for mounting on a drive spindle and with holes in the wall for receiving the opposite end portions of the metal bolts and wherein the opposite end portions of the metal bolts have threaded ends, extend through the holes in the wall and are attached to the core by nuts threaded thereon sufficiently to hold the segments on the core.

10. A grooved abrasive segment for constructing a grooved segmental pulpstone according to claim 1 comprised of a number of the grooved segments assembled about and attached to a core comprising:
a bonded abrasive segment of interfitting interchangeable reversible shape and predetermined size having a reducible outer grooved abrading portion, and surface interrupted by a' least one groove extending between one end and an opposite end of the abrasive segment and inwardly a pre-determined depth to a bottom of the groove, an inner non-abrading portion and surface adjoining the reducible outer grooved abrading portion;
attaching means for securing the abrasive segment to the core having a greater rate of thermal expansion than the segment fixed to and extending from the inner non-abrading portion with its end at and defining a circumferential boundary between the inner non-abrading and outer abrading portions situated at a distance no greater than 1-1/4"
(3.17 cm) from the bottom of the groove.

11. A grooved abrasive segment according to claim 10 wherein the bonded abrasive segment has an interfitting interchangeable reversible polygonal shape of predetermined axial length and circumferential width, at least one diagonal groove extending diagonally between the ends of the abrasive segment and wherein the attaching means comprises at least one threaded bore extending into the inner non-abrading portion from an inner surface thereof, at least one bolt each having a threaded end portion threaded into the threaded bore and fixed to the inner non abrading portion with its end at and defining the circumferential boundary and an opposite end portion adjacent to and extending from the one portion and adapted for attachment to the core of the pulpstone.

12. A grooved abrasive segment according to claim 11 wherein the at least one diagonal groove extends substantially through and intersects the center of the reducible outer abrading portion and surface of the segement.

13. A grooved abrasive segment according to claim 11 wherein the outer abrading portion has a pair of spaced diagonal grooves extending substantially parallel to each other and in opposite directions between the mid-point of the one and the opposite ends of the segments and diagonally opposite corners of the segments.

14. A grooves abrasive segment according to claim 11 wherein the opposite end portion of each bolt has one or more axially spaced grooves and is adapted to be embedded in a reinforced concrete core.

15. A grooved abrasive segment according to claim 11 wherein the opposite end portion of each bolt has a threaded end and is adapted to extend through holes in the wall of a hollow cylindrical core and attached to the core-by nuts threaded thereon sufficiently to hold the segment to the core

16. A grooved abrasive segment according to claim 13 wherein the outer abrading portion further comprises:
a central diagonal groove extending between the pair of spaced diagonal grooves, through and intersecting the center of the reducible outer abrading portion and surface of the segment.