CA1122012A - Abrasive brushes and methods of making same - Google Patents

Abstract

ABRASIVE BRUSHES AND METHODS OF MAKING SAME
Abstract Of The Disclosure An elongate, abrasive strip element is produced by winding an abrasive monofilament, or bundles thereof, back and forth in a zigzag pattern from side to side of the strip, and chain stitching together adjacent transverse sections of the mono-filament, or bundles thereof. The resultant strip is easily rolled or coiled about a transverse axis, but resists bending about a longitudinal axis, whereby it can be manipulated readily to form brush races of various configurations. The warp yarns which are used to produce the chain stitches may be produced on a knitting machine which can be cammed to vary the number of stitches between adjacent transverse strands of the monofilament wefts, thereby selectively to vary the density of the brush races produced from the strips, and also to vary the configuration of the abrasive strip itself (i.e. to produce it in linear form, circular, truncated-conical, etc.). The linear form of the strip may be severed medially of its edges to form two, identical bristle strips, each of which may be wound in convolute form, for example, and may be embedded at one side (e.g. by molding) in an elastomeric base to form a disc type brush. Other brush con-figurations are also disclosed.

Description

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1'h1B inventloo relate~ to hru.q}lc~, and more partlculnrly 1mproved abrasive brushe6 and the metllod~ Or manuracturln~ fiur,h brushcs .
There ha~ lon~ exi~ted a need ror a durable, ~are and lnexpensive abrasive brush element that l~ould be suitable for ue,e z on a multltude Or dlfferent surface~ or material~ and which could be de~igned to produce any one Or a plurality Or dl~erent flnlshes. Such uses include metal deburring, flnishlng, roughlng, material removal, poli~hing, cleaning and the like. More speclflcally, lt is desirable that ~uch brushes be suitabl~ for use on both regular and lrregular ~urraces~ and on material~
~alling in a range of from very hard to very ~oft. Also lt 1~
deslrable that the bru~hes be suitable for applications in which the brush i~ held stationary and the work itsel~ is moved, or alternatlvely, for appllcatlons in whlch the brush is reciprocated llnearly, or i~ rotated or moved ln an orbital ~ashlon at high speeds.
It has been discovered that particularly deslrable abraslve brushes can be produced by employing an abrasive monofllament material, such as ~or example, abraslve nylon monorllament~ of the type sold by Nypel Incorporated under the trademark "Nybrad", or by EI duPont de Nemours & Co., Inc. under the trademark "Tynex".
Generally these abraslve nylon monofilaments have encapsulated therein elther alumlnum oxlde or silicon carblde ~rlt particles, whlch normally are evenly distrlbuted throughout the mono~llament.
These abrasive filament3, by their very nature, pose many dlfficult problems in utllizine the fllaments ln con~unction with conventional brush-making apparatus. For example, the technlaue of trimming fini~hed brushes, which lncorporate this tyPe of material, i3 tlme-consumlng and expensive in view Or the rapid wear of the cuttlng edges of the trlmmlng tool.
Moreover, thls materlal, along wlth many other synthetlc rilaments, does not hold or blnd well ln a substrate when mechanically held in place with staple~, wire and the llke.

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For example, rotary brushe~ Or the t~pe whlch utllize two con-, centrlc rlngs having relatlve diameter.s such that the rlngs exert sufflclent pressure on the brush flber3 to hold them in the brush body~ as shown for example ln U. S. Patent No. 2,2~,337, often fail in use when abrasive brlstles are employedl because the brlstle material moves circumferentlally of the rlngs, thu~
abralding the rings and concentrating the brlstles ln localized circumferentlal zones, where they cause brush imbalance. This further produces uneven work on the surface that is being abralded, 0 and also produces undesirable vlbrations in the brush durlng u~e.
Also, brushes made with fibers which are mechanically tufted into either a rlgld or rlexible backing, generally have the dis-advantage that the fibers work loose during use, and cau~e the ~ame uneven work surface and imbalance that occurs in the case o~
the above-noted rotary brushes.
The abrasive nature Or monofilaments o~ the type described also make them impractical for use in channel brush methods Or manuracture, wherein short lengths of bristle are laid cros~wise to the channel with a wire or similar retainer lald across the ?~ brlstles in line with the channel, arter which the channel ls roll formed into a "U" shape around the bristles and retainer.
~orts to practice this channel brush method ln connection with the abrasive monorilament bristles have proved very unsatisfactor~
because the abrasive bristles prematurely wear the mechanical sorting and feeding device~ which are used in the process; and the brush material moves laterally in the channel and tends to concentrate in localized areas under load, thereby again causin~
uneven work surfaces and lmbalance in the brush. Additionally, brlstles tend to work loose from the retainer much in the same manner as in the case of the tufted t~pe of brush referred to above~

~l~Z~12 There is still another prior art method which has been attempted. A plurality of the abrasive monofilament bristles or tufts are arranged envely across a supporting surface, each fiber or tuft being separate from the others, and being individually aligned by orientation at right angles or some other predetermined angle to the plane of the support surface. The fibers are then encapsulated at their inner ends in a resinous backing, that can be modified to enable it to be wrapped onto a cylindrical cone, or to be formed into a belt, or to be cut into a variety of flat or disc-type shapes. The disadvantages of these types of brushes, however, is that they are limited as to the speed at which they can be rotated without causing undesirable failure or pull-out of the individual fibers from the resinous backing material.
It is an object of this invention, therefore, to provide an improved abrasive brush paving bristles anchored in a backing material, so that the bristles will remain fixed in the backing even when the brushes are operated at high speeds and under difficult load conditions.
To this end the invention consists of an abrasive member comprising an elastomeric support having there-through an axial bore and plane surface on at least one end thereof, a plurality of abrasive loops secured in said support, each of said loops being made from at least one synthetic monofilament element containing an abrasive grit distributed substantially uniformly throughout the element, and having at least one generally "U" shaped portion the closed end of which is embedded in said sup-port, said closed ends lying in a common plane adjacent ZO~Z

to and generally parallel with said plane surface, at least one continuous warp yarn embedded in said support and stitched to each leg of each of the embedded "U"
shaped portions of said loops, said warp yarn and the loops interconnected thereby being arranged in a spiral path around said bore, said elastomeric support material being bonded directly both to said warp yarn and to said embedded portions of said loops to provide a firm anchor for the latter, the legs of said "U" shaped portions of said loops being spaced further apart from each other - adjacent one end of said support than the other, and said brush being generally truncated conical in configuration.
Other aspects of this invention are claimed in our co-pending Canadian patent application Serial No. 308,311 filed on July 27, 1978, of which the present application is a division, and in another division thereof.
Other features of embodiments of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.

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Flg. l ls a rragmentary plan vlew Or a typical bristle . element produced according to ~his inventlon in strip form rrom an abrasive monofllament, and illustratlng diagra~matlcally ho~J
this strip may be severed medlally of lts edges to form two identical bristle strips suitable for use ln making abraslve bru~he~ accordin~ to this invention;
Fig. 2 ls a fragmentaYy plan view generally similar to Fi~. l, but lllustratlng a modlfied bristle element produced in strip form from a plurallty or bundle Or abrasive monofllaments;
~10 Flg. 3 is a sectional view taken along the line 3-3 in ~ig. 4 and illustrating diagrammatically part Or the apparatus and one of the method steps employed in producin~ a disc type brush from a convolutely wound bristle strlp Or the type shown ln Flg. l;
Fig. 4 is a fragmentary slde elevational vlew Or the apparatus sho~n ln Fig. 3;
Fig. 5 is an enlarged elevational view of the mold whlch is employed to apply an elastomeric base to the convolutely wound bristle strlp shown in Figs. 3 and 4;
Flg. 6 is a bottom plan view of the mold shown in Fig. 5;
: Fis. 7 is an elevational ~iew of the finished disc brush, portions thereof belng broken away for purposes of lllustratlon;
Fig. 8 ls a fragmentary plan vlew of a modiflcation o~ thls disc brush;
Fi~. 9 i~ a diagrammatic plan view generally similar to Flg. 4, and illustrating still another forrn of ab.r.a31ve b,rush made accordlng to this inventlon;
Fl~. lO ls a perspective vlew of a truncated conlcal brush whlch may be made ~rom a brlstle strlp produced ln accordance wlth this invention; and - 6 -~

~Z~12 ~ ig. 11 is a perspective view of still another type of abrasive brush which can be made from the novel bristle strips disclosed herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the dra~lnFs by numerals Or rererence, and ~Irst to Flg~. 1 and 2, 20 denotes generally an abraslve bristle element or strip, whlch can be used in manuracturing any one o~ a varlety of di~erent brushes made in accordance wlth thi~ invention. This element comprises a slngle abrasive mono-~ilament strand or brlstle 21, which is wound back and forthtransversely along the length of strip 20 in the form o~ a contlnuous weft, adJacent portions o~ which are bound together in known manner by a plurality o~ chain stltch warp ~arns 22.
A number of warp strands ?2 may be employed to hold adJacent portlon~ of the we~t filament 21 ln place. In the embodiment illustrated ln Flg. 1, two such chaln stltch chaln ~arp yarns 22 are knitted along each longitudinal edge of strlp 20 to functlon as so-called anchor warps which secure together ad~acent ends o~ the transverse portions of fllament 21 alon~
opposite sldes, respectlvely of the strip. Two addltlonal stitch warp yarns 22 are employed ln spaced, parallel relatlon ad~acent the center of the ~trlp 20 to retaln ad~acent mid-portions Or the monofllament 21 ln place. However~ lt will be understood that the number and types of warp yarns selected wlll depend upon the desired strength of the yarns, backlng absorptlon"backlng

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bondabllity, and the like. Yarns such as cotton~, wool, rayon, polypropylene, polyester, nylon or blends thereof are typical ror these warp yarn constructions. As noted above, the continu-ous monofilament 21 (the we~t) may com~rise an abraslve nylon monofllament of the type sold under the trademarks l'Nybradl', "Tynex'l, or the like.
The width of strlp 20 may vary depending upon the deslred trlm height o~ the resultin~ brush unit. For example, .strl~ 20 i5 normally deslgned to be twice as wide as the de~ired trim or finished height of the bristles on the brushes that are to be made from t~le strip. It is usually severed medially of its longitudinal side edges in a conventional manner by a slitter SJ
thus dividing strip 20 into two ~eparate brush strips 23 and 23', which are of equal helghts. The respective strips 23 and 23' are therea~ter incorporated into brush bases or substrates as noted herelnafter. j ~
The advantage of employlng bristle strips of the type denoted at 20 is that the abra~ive monorllament 21 can be pro-duced in a flexible, although somewhat rigid form, so that once the monofilament weft has been bent back and ~orth into its ~igzag con~iguratlon, it tends to remain in this positlon so that the strain on the chain stitch warps 22 is minimlzed.
Moreover, despite thls relative firmness of the mono~ilament 21, it nevertheless can be arranged on beams or creels in the usual manner so that it can be drawn lnto a knittlng devlce which forms the warp yarns 22 into the chain stitches as shown in Fig. l.
The two chain stltch yarns 22 located ad~acent the center of strip 20 are utilized to hold the transverse filament sectlons stralght during the slitting process effected by the slitter S, ~ 8 -~

11~2012 and also to malntain brlstle or filament integrity durin~
subsequent brush con3truction ~teps.
In Fig. 2, ~herein like numerals are employed to denote elements slmilar to those employed .~n the embodiment shown in Fig. 1, 25 denotes a modified bristle strip whlch ls produced from a plurality of abrasive monofilaments 21, which are fed in the form of a continuous bundle into a knittin~ machine (not illustrated), which stitches together the ad~acent portion~
Or the ~igzag bundle of filaments along the stitch lines 22 ln a manner similar to that in which the sin~le monofilament 21 i3 stitched in Flg. 1. As in the case of the first embodiment, two rows Or chain stitches are employed along each side of strip 25 to anchor or hold in place ad~acent ends of the transversely extending portions of the bundle of monofilaments 21; while two, spaced, generally parallel chain stltche~ 22 are employed substantially medially of the sides Or strip 25 for purposes similar to that descrlbed ln connection wlth the corresponding yarns ~n the first embodlment. Also as in the case of strip 20, the bristle strip 25 is adapted to be severed longitudinally and medlally Or its side edges by a 31itter S to divide the strip into two equal brush strips or elements 26 and 26'. In thls embodiment, of course, a plurallty of monofllament bristles are thus produced within each surrounding chain stltch, as compared to the single monofilament bristle whlch ls produce~ with-in each chaln stitch o~ the embodiment shown ln Flg. 1.
- One ma~or aclvantage Or producing strlps of the type denoted at 20 and 25 is that the spaclng of adJacent, transverse portlons Or the bristle fllaments or bundles can be arranged to be arithmetlcally repeatable by selecting the type Or chain stitch constructlon that will be produced by the as~ociated knitting machine. For example, by properly can~lng the needle bar on the _., g _, ~z~

assoclated knitting device, the machine wlll either place slngle filament sectlon~ side by side to form a solid array of bristles in a brush face, or, alternatively, it wlll vary the number Or stitches between each tran~ver~e section Or a filament (or section Or a fllament bundle) to create a space between ad~acent brlstles or bundles thereof. In thls manner it is po~slble to space the filament bristles ln such way as to produce almost any variatlon of brush face density deslred.
Although in the above dl~cus~lon it has been suggested that the strips 20 or 25 be severed medlally of their longitudinal slde edges, lt would be possible, of course, to ~llt the strip3 of~ center, thereby to produce two brush strips Or dl~simllar height.
One method of produclng a disc-shaped brush from a brush ~trip of the type denoted, for example, at 23 in Fig. l, ls , illustrated dlagrammatlcally in Flgs. 3 to 6, whereln 36 denotes a tubular hub or core around whlch the strip 23 i3 adapted to be wound splrally as noted herelnafter. The hub 36, which ma~ be constructed of metal or molded plastic materlal, serve~ both as a form around which the abra~ive strip 23 1~ wound, and also a~
a core for anchorlng the wound strlp ln a mold 40 (Fig. 5) that ls used for applylng an elastomerlc or slmilar base to the strip 23 as noted hereinafter.
In practice the hub 36 ls secured coaxlally on a spindle or shart 38 by a pair o~ clamps 37, wlth one end of the hub 36 (the rlght end ln Fig. 4) extending coaxially through a bore in a clrcular backlny, plate 35, whlch is also secured on shaft 38 against an enlarged-diameter collar 39. One end Or the ~trip 23 - is attached to the hub 36 with the severed end~ of filament 21 - 10 ~

~z~z faclng plate 35. The sha~t 3~ ls then rotated together wlth the bacl~ing plate 35 and collar 39, 90 that the strip 23 is spirally wound from a supply thereof around the hub 36, while being malntained under sultable tenslon by means o~ tenslon rolls 34 (Fig. 3) of any conventlonal design, Winding Or the strlp 23 is continued until a brush face is built up to the desired diameter agaln~t the face o~ the plate 35. During this windlng ad~acent portions of the convolutions of the strip 23 are secured in place by a flexible adhesive, -lO which ls applled along the anchoring edge of the strlp 23 adJacent the anchoring or dual warp strands 22. Thls adhesive i3 applled as the strlp 23 ls wound onto the hub 36 as shown ln Fi~Q. 3 and 4.
Therea~ter a dlsc-type brush ls formed by removing the wound strip 23, hub 36 and backing plate 35 from shaft 38, and placing thls assembly, with the dual stltched warp edge or anchor edge of the atrip racing downwardly, into either an epoxy or metal mold 40 tFlg. 5). The ~plral wound strip 23 rests upon a reinforcing layer 41 of fiber glas3 screen mesh or slmllar -20 material, which has been precut and placed ln the bottom of the mold 40 prlor to the lnsertion of the spiral wound strip. The ~creen acts as a reinrorcing agent for the brush backlng when encapsulated into the base o~ the completed brush. The hub 36~
centers the wound brush element 23 in the mold by preclsely flt-ting into a clrcu:lar notch or recess 42 formed in the base of the mold. At thi~ stage the base plate 35 acts as a mold cover and provides a level brush race when clamped onto the top of the mold 40 by conventlonal clamps,,not lllustrated.

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The mold 40, wlth the appropriate brush element in place, ls no.~ placed on the face plate (not lllu~trated) of a conventlonal ela~tomeric molding compound dispenser. The dl3pen~er i~ actuated to force a predetermined amount of molding compound lnto the mold through precisely arranged orlflces 43 (Fig. 5) located ln the mold base. The moldlng compound~ whlch i8 ln a llquid 3tate, rises ln the mold 40 to a predetermlned level ~or example as denoted by a broken llne at 44 in Fig. 5), at which point lt completely encapsulates each bristle at its anchored end to a level above the dual warp or anchor stitches 22.
When the elastomeric material, such as urethane or the like, has cured, the unlque anchor o~ this inventlon has been accomplished, and the completed brush 45 (Flg. 7) may be removed rrom the mold. The now-cured elastomeric material forms a relatively thin, flrm, flexible base 46 havlng an axial bore 47 for attachlng the brush to a mandrel or other motor-driven mount for rotatlng the brush 45 in contact with the work.
The tough urethane or slmilar elastomeric backing 46 encapsula~es the brlstles of the brush face at thelr bases to a predetermined height. This actlon provlde~ a mechanical bond to all of the construction elements. The warp materlals in the dual chain ~tltches absorb a percentage o~ the backing material thereby further lncreasing the bonding effect of the proces~.
Slnce each bristle fllament is lnterlocked by the dual chain stitches to all o~ the other brlstle filaments ln the brush, the brush face is further strengthened by both of the above actlons.
Thls combinatlon of actlons produces a brush face that ls partlcularly durable for appllcatlons requirlng rotatlon of brush 45 at high speeds, when lt is attached to a mandrel. Thl~ anchor also allows 100~ flexlbillty of the lndivldual brlstles wlthin thelr individual range of tenslle strength and bend recovery.
The brush made ln accordance wlth these teachlng~ wlll retain more brlstles when applied to sharp and ~meven edges and surfaces, welded studs and ~lmilar protrudlng obJects. The anchorlng ~ection or base 46 for the brush is thin in relatlon to the overall thickness Or the brush, so that the brush is relatlvely ~lexible ln directions transverse to the anchoring section enablin~ it to conform readily to uneven surfaces durlng use.
As previously noted, the spaclng Or the bri~tles withln the brush face can be predetermlned and controlled ln several ways.
First, the warp stitch yarns 22 can be arranged wlth or without spacer yarn~ that can locate the bristle filaments ~1 (Flg. 1) or bristle bundles (Fig. 2) ln a precise arrangement either - lmmediately ad~acent to each other~ or a de~inite distance apart.The center warp stitches, whlch are located at or near the face Or the completed brush, can be altered ln size and location lndependent of the anchor warps and spacer yarns to control the orientation o~ the brl~tle ~rom 90~ perpendicular to the base to an angle of several degrees from the perpendicular depending on the application. Secondly, bristle orientation may be achleved by controlling the warp yarn spacing. This i~ called a controlled gap knit wherein a controlled spaclng can be maintalned between bundle~ or bristles.
Still another means of orientin~ the brush bristles is shown in Fig. ~, wherein flexible spacers 49 are located in between ad~acent convolutions of bri tle elements ln a modlfied disc type bru~h 45'. The spacers 49 may be fed between ad~acent convolutlons a~ the brush element is bein~ spirally wound onto a - ~3 -~Z~

core a~ shown for example in Fig~. 3 and 4. Moreover~ ~lmll~r spacers, if deslred, may be provlded to control latQral spacing of brlstles in a llnear brush unit.
It 1~ also possible to construct a rotary brush by ta~ing the el~ment 20 shown in Fig. l and wrapplng lt concentrlcally upon it~elf as shown in Flg. 9 around a hub 50 to the deslred diameter. As the strip 20 is wound concentrically around the hub 50, an adhesive material ls added bet~een ad~acent convolutlon~
to contaln the wound strip in the form of a ~rindlng wheel. The center llne warp~ 22 remote from the side edges of strlp 20 are removed as the element is wound~ thereby exposing a~ much abraslve surface as po~slble. The completed brush may be removed from the hub 50 and secured to a drlve shaft for use as a ~rind stone.
The encap3ulation o~ basically any construction of abraslve filaments as descrlbed previously can be accomplished to broaden thè use of the lnventlon to soft or hard abraslve or finishing wheels. Figs. lO and 11, for example, illustrate diagrammatlcally various loop arrangements of filaments which are encapsulated in a hard or so~t elastomerlc compound. The wheel in Fig. lO
~0 comprises a modified strlp 20 or 25 which is wound about a core ~hat has an axis extending transverse to the length of the strlp, thereby to form a truncated conical bristle element which is embedded in a truncated conlcal body 61 Or elastomeric materlal.
In this embodiment the anchoring stitch warps 22 adJacent one slde of the modlfled strlp 20 or 25 may be made to allow the adJacent sections of the monofllaments 21 to be spread further apart along one ed~e of the strip, thus to allow the wound strip to assume the truncated conlcal conflguration.

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In the embodlment shown ln Fig. 11 the strip 20 or 25 ls modified sll~htly further to space portlons Or the monorilaments 21 substantlally rurther apart along one slde of the strip than at the other, whereby one or more such strlps may be formed coaxially about a core 80 that the transverse sectlons of the mono~ilaments ln each strip flare radially outwardly as spokes from the hub. When one or more such strips are embedded in elastomeric material 62, the wheel-shaped brush of Fi~. 11 is produced.
One o~ the most important advanta~es of abrasive brushes Or the type descrlbed ls that the firmly anchored abra~ive bristles not only abraid or pollsh a ~ork surface, when in use, but also simultaneously deposit a thin organic fllm of nylon on the sur~ace as the nylon matrix ror the abrasive partlcles wear~
away durin~ use. Thls not only helps to prevent unde~irable oxldation of metallic surfaces, but also provides a longer lasting bright finish on aluminum, magnesium or steel panels J when used to polish same, and a better bond for organic palnts or rlnlshes applied to the panels In all of the previously descrlbed brushes, the mlnimum Or anchor actlons are always three: the mechanical linkage Or the individual group~ Or ~ilaments 21 (or bundles thereof) and the ~arp stitch yarn~ 22 throu~hout the construction; the mechanical interaction Or the elastomeric base material and the groups or lndividual filanlents 21; and the chemical bond interaction or ruslon Or the base materlal with either or both the ancho~ warp yarns 22 and the f'ilaments 21 themselves.
Although not disclo~ed in detail hereln, it wlll be apparent that other types of abraslve bru~hes may be made from bristle strlp~ o~ the type shown in Fl~s. 1 and 2. For example, one or more bristle strips 23 could be used to form linear (rectangular)brushe~ by pa~sin~ a 3trip 23 throu~h the cross head Or an extruslon uie, whlch ~ee~ a p:Lastic materlal to the ba3e or anchorin~ ed~e o~ the 3trlp as lt pas~es throu~h the die and the assoclated shapin~ shoes. The pla~tic base produced by this process may have any one Or a plurality o~ different cro~s sectlonal conrl~uratlon~, and may be used to mount the brlstle ~trlp ln a corre~pondingly shaped groove or recess in a brush body or the llke.
The here~n de~cribed con~tructlon~ orfer disc, llnear or rotary brushes with a securely anchored ba~e constructlon and a unlform finl~hing periphery portion, which ha~ been ~ound erfectlvely to resist bristle 105~, unraveling, and disintegra-tion to which prior davlces Or this sort have been 3ub~ect.
Whlle appllcant'~ lmproved brushes accompll~h the ob~ects Or the inventlon, and while only certaln preferred embodiment~ and details Or structure and methods o~ constructlon have been descrlbed ln detail herein, lt i9 understood that thls appllca-tlon 18 lntended to cover any other modiflcations that may fall wlthln the scope o~ one skllled ln the art, or the appended claims.

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Claims

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

1. An abrasive member comprising an elastomeric support having therethrough an axial bore and plane surface on at least one end thereof, a plurality of abrasive loops secured in said support, each of said loops being made from at least one synthetic monofilament element containing an abrasive grit distri-buted substantially uniformly throughout the element, and having at least one generally "U" shaped portion the closed end of which is embedded in said support, said closed ends lying in a common plane adjacent to and generally parallel with said plane surface, at least one continuous warp yarn embedded in said support and stitched to each leg of each of the embedded "U" shaped portions of said loops, said warp yarn and the loops interconnected thereby being arranged in a spiral path around said bore, said elastomeric support material being bonded directly both to said warp yarn and to said embedded portions of said loops to provide a firm anchor for the latter, the legs of said "U" shaped portions of said loops being spaced further apart from each other adjacent one end of said support than the other, and said brush being generally truncated conical in configuration.