CA2035414A1 - Method and apparatus for abrading - Google Patents

Abstract

ABSTRACT

METHOD AND APPARATUS FOR ABRADING

An abrading apparatus for abrading tire tread compounds has a plurality of test stations (14) and a drive module (16) coupled to the test stations. Each test station (14) has a grindstone (20) and a sample wheel (24), both of which are rotatably driven by the drive module (16).
Each sample wheel (24) has an outer layer made of the tire tread compound to be abraded. The sample wheels (24) are engageable with the grindstones (20) to abrade the tire tread compounds against the grindstones. Each test station (14) also has a dust transfer wheel (40) engageable with the sample wheel (24), and a chalk member (44) engageable with the dust transfer wheel (40). The chalk member (44) transfers chalk dust to the dust transfer wheel (40) which, in turn, transfers chalk dust to the sample wheel (24), to dust the interface between the sample wheel (24) and the grindstone (20).
The drive module (16) has a gear assembly (78, 88, 90, 92, 94, 98) to change the velocity of the sample wheels (24) relative to the velocity of the grindstones (20), to adjust the slip value and, therefore, the degree of abrasion of the sample wheels (24). The abrading apparatus can be employed to abrade tire tread compounds at different levels of abrasion severity, to predict the irregular wear resistance of the compounds.

Description

.3 ';

~E~OD ~ND A~P~8 ~OR ~aD~N~

F~ld o~ th- ~nv~t~oD

The prQ~ent invQntion relatQs to apparatu~ and method~
for abrading. MorQ particularly, th~ pre~e~t inv2ntion rQlatQq to apparatus and m~t~od~ ~or abrading tir~ tr~d compound~ or other typQ 0~ rub~r compound~, to mea~ure thQ wear rats, wear r~istanc~ and/or abrasion re~3tance o~ th~ co~pound~ undQr dl~r~nt wear ~v~rity conditlon~.

~c~gro ~a~or~S~o~
:
Xnown app~ratu~ ~or abrading tlr~ tr~ad~co~m~ound~ or othQr typ~ o~ rubber co~pound ,:q~n~ra}ly compri~Q a tsst station that ha~ a: ~oving abra~iv~ ~ur~ac~. A
~a~plo o~ t~ co~pound is engag~d wit~ th~ moving a~raalva sur~ac~ to b~ abrad~d. ~h~ amount o~ ~aterial abrad~d ~rom th~ sampl;~ i t~n~ea~urQd to pr~dict the ~
wear rat~,:w~ar re~istanc~ and~or~abrasion r~ tanc~ o~ :
tha tirQ` tr~ad co~pound und~r~actual tir~ w~r, or~other abrading cond~tlon~
:~
One problem with so~ known abradlng~apparatu~ i5~ that thay~co~pris~:only~ on~te~st~;statlo~n~and, thare ore, : :
: ~requcntly~tak~ :a:long~time t~o;~t;~st a~co~pound.
Moreover, tha te~st~va~riabil~ity~:inher-nt in~a single test sta~ion usually canno~:b~ account~d:~or. :;As a result, ~:

the abra~ion data provided by such apparatu~ ~requently do~s not provide an accurate basis ~or predicting actual w~ar characteri~tic~ o~ tire tr~ad compound~.

Anoth~r probl~m with ~om~ known abrading apparatus i3 that the 3urfac~ condition o~ th~ interfacQ between ehe grin~tonQ and th~ pl~ compound i~ not properly controlled. With tir~ tread co~pound~, ~or Qxa~ple, an oily layar of dagrad~d rubb~r ~t~rial o~tan ~OD on the contact ~urfac~ o~ tha grindston-. Th~ oily layer reduca~ the dQgr~ o~ abra3ion by th~ grind~ton~. As a result, such apparatu~ will lik~ly provid~ inaccurat~
abra~ion data ~or predicting th~ wo~r rat~ o~ tha compound.
Anoeher proble~ with known abradlng ~hod~ and appa~atu~ i3 that abra~on data i~ provid~d to pr~dict tread w~ar a~ on~ level, or an aYerag~ l~vel o~ abra~ion sevority. Howaver, ~or 3011~19 tir~ troad co~pound~, th~
20 r~lativs t~e~d woar charact~ri~tic~ ~y vary dramatically at dif ~er~nt l~v~l~ o~ abra~ion ~Q~arity .
For exa~pl~, 90D~III tir~ tr~d coE~pound~ d~on~tratQ high tr~ad wa~ capabiliti~s a~ lo~lr $~v~rity l~val~ o~
abra~lon, whlla d~onstratir~g v~ry poor tr~d w~r 25 capabiliti~ at high ~ev~rity 1QV~1~ 0~ abra~on. A~ a ra~ul~, known ~rading appar~tu~ t~at ahr~d~ at only one 1QV~1, or an av~ragf~ 1QV~1 0~ abra~ion ~ rity, fr~ ntly proYià~ leadinq ~ra~lon da~aO

30 ~or exampla, i~ such an app~ratu~ i~ u~d to t~t a tire tread compound at ~ low level o~ abr~ion ~v~rity, it may inàica~ excsll~nt tread p~r~onn~nco whil~, in fact, at high sev~rity l~v~l~ of abra~ion th~ a~ compound may provida v~ry poor tread per~onnanc~ uch a tire 3 s tread coD~pound w~rs then used to ula~ ~ tlr~ and subject~d to h~ s~v~rity abra~ion, ~uoh ~ a per~or~anca car tire, thQ tire would likaly exhibit a high wear rate and/or d~velop an irregular w~ar pattern.

one proble~ with tire tread compound~ that exhibit S widaly differe~t wear rate characteri-~tic~ at di~erent lev21s of abrasion sevQrity, i~ that tir~ mad~ ~ro~
such compounds frequ~ntly dev~lop irregular wear p~ttarns. It ha~ bQen d~t~r~ined thAt irrQgular we~r i often caus~d by th~ l~n~v~n di~tribution o~ ~tr~s in the tread of the tir~ th~ tlr~ trQad compound Qxhibits low abra~ion r~ tanc~ at hlgh s~vQrity l~v~13 o~
abra~ion, th~n th~ ~ect~on~ o~ th~ tir~ a~ectQd to ~he higher 1QV~1S 0~ ~everity or 8tr~ will w~ar ~a~r ~han ~ other section~ oS th~ tl~. A3 a r~ult, such tires frequently dQvelop irregular wQar patt~rn~ that sub~tantially decr~as~ th~ o~ th~ tire~

Th~re~or~, it i~ critical to b~ abl~ to t~gt thQ
abrasion cAarac~sri~tic~ o~ so~ tir~ ~r2ad co~pounds at both hiqh and low s~ority l~v~l~ o~ abr~ion. B~cause ~nown m~thods and apparatu~ havo not b~n u~d to pQr~or~ th~ ~unction, ~uch compounda r~ u~ually te~ted by actu~l tir~ t~ on roAd v~hicl~ und~r both high and low s~Y~rity ~bra~ion cond~tions, which i~ a ~ime-consu~in~ and ~xpen~iv2 procedur~.

It 1~ ~n ob~ct o~ thOE pr~s~nt inv~ntlon, th~r~or~, tooverco~ th~ probl~s and draw~ack~ o~ known ~brading ~Qthod~ and app2ratus.
8 ~ ary o~ th~ ~a~tio~
.
ThQ pre9ent invention is direct~d to an app~r~tu~ for abrading carbon black containing co~pound~. Th~
apparatu~ comprl~ a fra~, a ~otor, and a plurality of e~t station~ suppor~ed ~y t~ ~ra~o. Each t~ .taeion ~ ; , r , , .

include~ a grind~tone which is coupl~d to, and rotatably driv2n ~y the motor. Each test station al~o includ~s a sampls wheQl, which i~ al~o coupled o and rotatably drivsn by tha motor. Each ~ampl~ wheel includs~ a S carbon ~lack containing compound to ba abraded, and i~
Qngag~abl~ wi h th~ grindston~ to abrade th~ carbon black containing co~pound again~t th~ g~ind~tono.

E~ch t~st station ~urther include~ a du~t tran8~8r wheel engagQabl~ with tha ~a~pl~ wh~l, and ~ ch~lk me~r engag~i~bl~ with th~ du~t tran~r who~l. Tho chalk ~mb~r tran~ar~ chalk du~t to th~ du~t trans~er whe~l.
Th~ du~t tran~r whsel in tu~n tran~r~ chalk du~t to t~ ~a~pl~ wh~l, to du~t t~ int~r~c~ b~tw~Qn th~
~ampl~ wh~sl and th~ grindston~. A ~lr~t gear ~emb~r i~
couplcd to the motor, th~ a~pla wh~ol~ and th~ .
grindstones. Th~ ~irst ~ear ~e~b~r i~ ~Qlec~d to ~et ~he v~locity Or tha ~ampl~ whe~l~ r~lative to the velocity o~ th~ grind~tonQ~ and ther~or~ ~t th~
~0 de~ o~ abra~ion o~ th~ ~ampl~ wh~ls by th-grindston~ .

In an app~r~tu~ oS th~ pr~ent invantion, ~ach ~e~t station ~urth~r includes a fir~t wQight coupled to the ~5 ~a~pl~ w~o~ hQ first w~ight i~ sol~ctQd to ~ tha ~o~c~ o~ ~h~ plo whe~l ag~in~t t~ grind~ton~, and thu8 ~t th~ d~gr~ o~ abra~i~n o~ t~o ~pl~ wh~l by th~ grind~ton~. Eac~ ~e~t st~tion ~urth~r lnclud~ an ~lastic ~mb~r coupl~ to tho du~t trAns~r wh~l. The ~la3tiG ~b~r i~ located betw~n th~ du~t tran~r whc~l and t~ sa~pl~ wheel. Th3 ch~lk ~mb~r tran~er~
chalk dust to th~ ~lastic me~b~r, which in tu~n trans~r~ chalk du~t to the sa~pl~ whe~l.

In an app~r~tu~ o~ thQ pr~sent invention, ~ach t~t ~tatlon furth~r ~nclud~ a 5~cond w~ght coupl~d to t~e du~t tran~rex whe21. The seco~d weight i~ s~l~ct~d to set t~e ~orc~ o~ the du~t tran~er wh~l and, thQrQ~ore, the ~la~tic memb~r, against the ~ampl~ whe~l, to control the amount of chalk du~t applied to the Ra~pl~ wheel.
Ths chalk member is made ~rom a mixturo including ~agne~ium hydroxide, plaster o~ paris, and water.

In an apparatus of tha prasQnt invention~ a ~ir~t ~ha~t i~ coupled to the first gear ~mb~r, tho ~otox, and to t~o ~ampl~ whQ~l~. Th~ ~ir~t sha~t 1~ rot~tably drivan by t~ motor to rotatably dxiv~ th~ ~ampl~ wh~ls.
~Qcond s~a~ coupled to th~ ~ir~t g~ar ~ber, ~h~
motor, and th~ grindstone~ to rotatably drivo th~
grindQtones. The firs gear mQEb~r i~ s~l~cted to SQt lS the v~locity o~ th~ first sha~t r81ative to th~ velocity o~ tha second sha~ and, th~reforQ, ~t tho v~locity of the ~ample wheels relativ~ t~ th~ v~locity o~ th~
grindstona.~ .

20 An app~ratus of the pr~3~nt inv~ntion ~u~h~r compris~3 a ~acond gear mo~ex coupl~d to th~ ~lr~ ~ha~t and ~o tl~Q ~ir~t g~r ~ r. Thæ ~lr~t ~ha~t dr~v~ th~
second gaar ~eD~b~r, and th~ $~cond g~ar ~ r in turn dri~ the ~ir~t gear m~mbQr. A third g~ar D~ r i~

2 5 coupl~d to thl~ s~cond sha ~t and to tho ~lr~t g~ar l~l~r- ~h~ ~ir3t gear ~ r driv~ a third g~e~r m~ r, and ~ thirà g~ar r~nb~r in turn driv~ tn-~sQcond sha~t. Th~ relativQ v~lociti~ oP th~ ~lr~t and s~cond sha~t~ and, ther~or~, th~ r~latlv~ v~locities of 30 th~ ~mpl~ wh~el~ and th~ qrind~ton~, r~p~ctiv~ly, are sot by sale::tlng tA~ size o~ th~ ~r~t g~ar D~ r. The first ~haf'c and the sec:ond sha~t and, tllar~oro, th~
sa~pl~ wha~l~ and ~che grind~tons~, r~ poctiv~ly, are rotatably drivon in opposit~ dir~ction~
Tho p~s~ont inv~ntion i~ al30 dir~lilCtQCl to al ~IIIthOdl 0 ~ ~ t:? '`` ~

abrading tire tread compound~. The ~ethod of the present invention includes the R~ep~ o~ weighing at least two sample wheels, wher~in each ~a~ple wheel includes a tira tread compound. Each sample wheel i4 abraded by being rotated in engagem~nt with a respec~ive grindstone, wharein th~ relative v~locitias o~ tha ~ampla whe~ls and the grind~tono~ deXin~ a ~ir3t ~lip value. ThQ weight of Qach sample wh~ then measured to measura the loss o~ the tir~ tread compound at tha ~ir~t slip valuo. The sampl~ wh~ls are th~n abrad~d by rota~ing each samplQ wh~ol in Qn~ag~nt with a re-~pective grind~ton~ at a ~cond ~lip valu~. Each sample whe~ then weighed to ~a~ur~ tha lo~s o~ the tire tread comp~und at th~ econd ~llp valu~. Th~
samplo WhQ~ls arQ th~n abrad~d by rotati~g ~ch 3a~ple whael in engage~nt with a ra~p~ctive grind~tonQ at a third Ylip valuo. Each ampla whQ~ th~n w~igh~d to measur~ tha los~ o~ the tir~ tread co~pound at th~ third slip value.
In accord~nc~ with a ~Qth~d o~ th~ pr~ent inv~ntion, each slip valu2 i~ ba~d on thQ di~f~r~nc~ b~tw~n the volo~ity o~ th~ ~ampl~ wh~ols ~nd th~ v~locity oS the grind~on~, dividQd by th~ v~locity o~ tho sampl~
wh~ . Th~ ~irst 31ip valu~ is wi~hin th~ rang~ o~
about S to 9%; th~ ~ocond slip v~lu~ i~ within th~ range oS about ~ to 17%; and tha ~hird ~lip valuo i~ wl~hin tho ran~ o~ about 11 So 30~. Pr~r~bly, th~ ~ir~t slip valuo i~ about 7~, the ~cond ~llp ~aluo i3 about ~3%, and th~ t~ird ~lip valu~ i5 about 21~.

Th~ pre~ent invention is al90 dirQCtQd to a ~thod of abradin~ a c~rbon black containing co~pound. Th~ ~ethod include3 ~ step~ o~ weighing e~ch o~ a plurality o~
sa~plo ~b~r~, wh~r~in an out~r ~ur~ac~ o~ ~ach sa~ple m~ber i~ ~adæ oP a c~rbon black contain~ng co~p~und.

The sample m~mber~ are each abraded in rotating engagement with a r2sp~c'c$vu ~brasivo membs~r. The velocity of the 5amp1Q m~mber~ relative to th~ velocity of th~a abrasiv~3 mQmber~ de lne~ a ~irst ~lip value. The S Yample members ar~ then abrad~d in rotzlting engagement with at least on~ other ab~aslve m~mbar at the ~ir~t slip value. The los~ o~ th~ car~on black containiny compound ~ro~ each ~ample mefflbar at th~ ~ir~t ~lip value is t~lan ~ea~ured.
'r~e sa~nplQ m~ r~ are th~n ab~ad~d in rotatlng engag~ment with r~spect~ ve~ abra~ivo m~a~bQr~ at a ~Qcond ~1~ p ~aluo . Eac:h sa~Dpl~ m~ r 19 th~n abraded in rotating engage~nt with at l~a~t o51~ othar abra~iv~
15 m~mber at th~ ~cond ~lip valu~. Th6~ lo~ o~ ~ha carbon black containing co~pound ~ro~ ~ach ~ampl~ r at the econd 31ip valuQ iq t~n m~ ured.

In on~ thod of thQ prQ~nt inv~ntion, ~ach sampl~
20 ~ber i~ rotat~d wlthin 'c~e~ rang~ o~ about 10, 000 to 20, 000 rQvolution~ with Qach abra~iv~ r. The ~ampl~ mo~Qr~ ar~ also rotat~d within th~s r~ng~ o~
about 800 to 900 RP~ wit2~ ~ac~ abra~lYo 3~ r. T~Q
ambiQnt t~p~ratur~ o~ th~ ~aDlpl~ rs and abrasivQ
25 m~b~r~ i~ controll~d, to control th~ d~r~a o~ abra~ion o~ ampl~ m~o~3 ~y th~ abra~ r~. Th~
aubi~nt t~2peratur~ is pr~rably ~intain~d wi~t.in the rango o~ about 40- to 55 C. Th~ volu~a lo~ p~r unit of travQl o~ eac~ ~a~apl~ r at ~ch ~lip valu~ i~ than 30 `calculated. Th~ volu~ lo$~ i~ ba~ld on th~ ~oasured weight los~ o~ ~ach ~a~pl~ b~r and th~ da~ity o~ the carbon black containing compound.

On~ advanta~o o~ th~ m~thod and apparatu o~ th~ present invontion, is that any inherent v~ri~bility in th~
abra5iv~ne~ o~ th~ individual abra~v~ r~

minimized by abradinq each sample wheel or member against sevaral abrasivQ memb~rs. ~noth~r advantagQ o~
thQ preaent invention, is that th8 sampl~ whe~l~ or mem~er~ can be abraded at dl~erent ~lip value~, and thu~ dif~er~nt levels o~ abra~ion severity. Th~rQ~ore, the degree o~ irregular w~ar rP~i3tance o~ the tir~
tread compound can bQ predicted based on th~ ~easured wQights o~ tha sa~pla wh~al~ after abra~ion at each Rlip valuQ. Known abrading method3 and app~ratu~, on the oth~r hand, w~ich usually abradQ at only on~ lev~l, or an av~rage 1~VQ1 og abra lon sov~ri~y, gon~rally cannot ba u~ed to accuratæly pradlct irregular w~r re3istanc~.

Anoth~r advantag~ o~ tho pr23~nt inv~ntion, i~ that t~e chalk ~e~bsrs and du~t tran~f~r wheels apply thin ril~8 o~ chalk du~t to the intQr~ac~ b~twean th~ re~pQctive ~ample whRels and grindstona9. A~ a rQ~ult, th~ chalk du~t pr~vent3 an olly lay~r o~ degrad~d rubb~r ~atQrial ~ro~ dav~loping on th~ int~r~ac~ batw~n ~aoh ~ample ~O wha~l and its re~p~ct~v~ grind~tona. An olly layS~r would r~ducQ thQ d~grS~ o~ abra~ion o~ a ~a~plS~ whe~l a~
a giv~n ~l~p v~lu~, and thu. caU8~ t~ appara~u~ to provid~ inaccurat~ abra~ion data.

Oth~r adv~ntag~ o th~ pre~snt inv~ntion will b~co~Q
app8r~nt in viaw o~ tho following d~t~ d d~criptlon and drawing~ tak~n in connect~on t~r~v~th.

arlo~ Do~o~ o~ o~ t~ ~r~ffl~q~
Figur~ a partial front plan vio~ o~ an abrading apparatu~ embodying th~ pre~nt inv~ntion.

Figuro 2 i3 an enlarged, side plan vi~ 5~ a t~ t ~S station o~ th~ appara~us of Figur~ 1 tak~n along th~
1 in~ A-A .

Figur~ 3 i~ a partial cut-away, side plan view of the apparatus o~ Figure 1.

Figure 4 i3 an enlarged, front plan vi~w o~ the drivQ
~odule of ths apparatus o~ Figure 1.

FigurQ 5 is a partial cut-away, top plan view o~ the drive ~odul~ of Figure 4.

FigurQ 6 i~ a ~id~ pl n view o~ th~ driv~ ~dule o~
Figur~ 4.

Figura 7 is a partial schematic illustrati~n o~ th~
apparatu~ o~ Figur~ 1 illu~trating the order o~ abrading sQveral ~ample wheel~ in accordanc~ with th~ pre~nt inv~ntion.

D~t~ a~ari~o~

In FigurQ 1, an abradln~ æpp~r2t~s a~bodying th~ pres2nt invention is indicated g~n~rally by kh~ r~e~ncQ
numaral 10. T~ apparatu~ 10 compri~ a cabinQ~ 12, and tw~lv~ t~t station. 14 ~only six shown) nounted ~n~-to-~nd wit~in t~ cabinQt 12. ThQ apparatu~ 10 25 th~r~ora ha~ a righ~ bank and ~ l~ft bank og t~t statlon~ 14, each bank including ~ix te~t ~tation~. The app~ratus 10 ~urther compri~s~ ~ dr~vo ~odul~ 16 2Dounted in about t~ middl~ o~ tha ca~in~t 12 to drivG~ thQ test stations 14, as will be de~cribQd furth~r b~lo~d.
E~rery two t~st station~ 14 are mount~d wlthin a ~e~t fraD~ 18 which i~ gen~rally U-shap~d, a~ ~hown ~n Fig~lre 1. In Figuro 2, a typical t~st statlon 14 1~ ~howrl in further datail. Th~ test station 14 coD~pri~e~ a 35 grindston~ 20 which i~ k~yed to a grind~ton~ drlv~ sha~t 22 . Th~ grind3tons driv~ sha~t 22 i~ ~ ournal~d ~o ~he front end o~ thQ t~ t frame 18. The grindstone 20 i~
dulled by conditioning with nylsn wheels to raIaove any sharp proj ~ction~- on its periph~r~l or abrading ~ur~ace .
~y dulling tho grindston~ 20, cutting abra3ion i3 S aYoided, wllich would adver~ly a~ct th~ abrasion te~
per~orm~d with the apparatu 10.

As shown in phanto~ in Fl~ure~ 2, t~a ta~t station 14 ~urther co~pri~e~ a ~ampl~ wh~l 24, which i~ k~y~d l:o a 10 ~ir~t ~aDIplQ wt~l driv~ s~a~t 26 lm~di~t~ly abova tha grindstonQ 2 0 . Th~ ~ampla wh~l 2 4 co~pri~l3 a s~
core 25 ( sho~n in phantom) and ~ layor Or ~aD~plQ
matarial compr~slon molded ov~r th~ ~t~l corQ. Th~
~ampl~ mat~rial is, ~or exaDIplo~ a carbon blaek 15 containing tir~ trQad compound. Typic~lly, th~ lay~r of samplQ matlrial ig on thQ ord~r o~ ~bout onQ-half to ono-inch thicX. Th~ sampls wh~al 24 ~s~ mold~d by cutting a strip Q~ th~ tirQ trQ~d co~pound and wrapping thQ strip around the 3teel1 core~ 2S. ~Q strip i~ ~hen ~0 colQpro~1orl mold~d onto th~ ~t~21 cor~ 2S ~d~r h~at and pressurQ within a suitablQ di~, in a mann~r known to tho~ ~kill~td in th~

As ~hown in ~urQ 2, the sampl~ wha~l driv~ ~ha~t ~6 is 25 journ~lad to tho ~rQ~a end o~ a 3a~lspl6~ wh~ ra2lo 27.
~ pl~ wh~ r~ 27 i~ in tu~n ~ournals~d on on~
and to t~ ~r~ 18 abou~ a s~con~ ~ampl~ wh~l driv~
sha~t 28. T~ s~cond sampl~ wbQ~l dri~ ~h~Pt 28 is j ournaled to th~ top, bac~c end of th~ ~ra~ lg . Th~
30 sampl2 wh~ol ~ramel 27, ~herQfor~ pivot~d abou~ e second sampl~ wh~l drive shaft 28, to ~ovo ~ch- sample whe~l 24 in~co and ou~ of engag~D~nt wit~ th~ grlndstone 20. Th~ norn~al force of the sa~pl~ wh~ol 2~ ~ainst ~he grind~tone~ 20 i~ controlled by ~ count0rw~1ght 29. The 35 counterw~i~ht 29 i~ su~pendQd ~rom tho ~r~ ~nd ol! the amplo wh~l fra~a~ 27 by a cord 30, as ~hown ln Fl~ure 2. Thu~, the da~rze Or abrasion by th~ grind~ton~ 20 against th~ sampl~ whael 2~ can be partlally ad~u~ed by adju~ting the weight of th~ counterweigh'c 29.

5 The te~t station 14 furthQr comprise~ a ~lr3t ~procke~
31, which ic~ keyed to th~ fir~k ~ample wh~Ql drive shaft 26 ad~ac~nt to th~ ~a~ple w21e~1 24. A sQcond sprocket 32 is lcQy~d to th~ ~acond saDIple whe~l driv~a 32la~t 28 and i~ located in~lln~ with th~ Sir~t sprock~t 31. A
10 ~ample whe~l driv~ balt 34 i~ mounted ovar ~ ~lrst sprocXot 31 and th~ sacond sprockat 3 2 to driY~ 'che ~procket~ and, th~r~or2, drivo th~ a~aplo wh2~1 24. As shown in Figur~ 1, th~ s~c:ond ~ample~ whe~l driv~ shaft 28 i~s coupl~d to the driv~ ~odulQ 16, and thus drive~
15 th~ ~a~ple wh2~1 24, a~ wil~ b~ d~scrib2d ~urth~r below.

The test stat1 on 14 furth~r co~pri3~ a du~t whe~l frame 36, ~ournalQd on one end to t21n ~a~pla wh~ ramlla 27 by a bQ~ring support 38. A du~t txan~f~r wh-~l 40 i~
2 0 ; ournaled on th~ ~r~8 end ~r ~ du~ wh~ ra3l~Q 3 6 by a b~aring ~upport 4 2 and, a.~ ~hown in Figur~ 2, i~3 angag~ wi'c~ th~ 3a~pl~t wh~l 2~ du;~t wh~l fram~ 36 thoro~or~ i3 pivot~d about th~l b~r~ ng 3upport 38 to ~ov~ du~t ~rans~er wha~l 40 into and out o~
~5 engagQ~nt with the ~ampl~ whe~l 24 5h- t~t ~tation 14 furth~r co~prl3l~ a ch~ tick ar~
44, which is pivotally moun~d on on~ ~ndl to thæ s~aple wh~ ra~o 2 7, ad~ ac:ent to ~h~ du~t wh~ ra~o 3 6 . A
30 chalX ~tlcX 46 is n~ount2d on ~ r~ ~nd o~ chalk .~tick arDI 44 by a bracket ~7. A~ hown iA Flgur~ 2, t~le fre- ~2nd o~ the~ chalk stlck 46 is ~Daintain~d in engageman~ with thet dust tran3~r wh~cl 40, und~r 'che w~ight o~ the~ ~halk tick 4 6 and t~ chalk ~tick ar~ 4 4 .
~5 Th~ brack~'c 47 is claDIped over th~ chalk ~tick 46 and fa~t~n~d by a scr~w 48 to hold th~l chalk ~'cick in place.

~3~

Tha chal~ s~ick 46 i~ made pr~Serably ~ro~ a mixtura o~
magna~ium hydroxid~, plastQr o~ pari~, and de~in~rallzed wa~ar, and i~ provided to trans~r a light film o~ chalk d~st to tha dust tran~r~r wh~el 40. Sev~ral chalX
sticks may he made, ~or exa~ple, by mixing about 170 gram~ ("gm") o~ plaster o~ paris, 80 g~ o~ magnesium hydroxide, and 153 g~ o~ demineralized watar. Tha mixture i3 then poured lnto a mold and allow~d to harden ~or about one hour. ThQ chalk i~ th~n ramoYQd ~rom the mold and heated at about 100-C ~or on~ day. A~t~r heatlng, th~ chalk i~ then cut into individual chal~
~tick~ 46.

Tha du~t transfer whe~l 40 compri~es a rubber core 50 and a foa~ outRr lay~r 52, whlch i8 pr~Eably a polyurathan~ ~oa~ A rubb~r b~nd S~, which i~ about the samQ width a. th~ rubbQr core 50, i~ fitt~d around thQ
foam outer layQr 52. The rubb~r band 54 i~ tAu~
maintainQd in engag~m~nt with both th~ 3ampl~ wheel ~4 and th~ botto~ end of thQ chalk ~iCk 460 Th~ rubbQr b~nd 54 r~cQiv~ chalX du~t ~ro~ t~Q chalk ~tick ~ and, in turn, tran3~rs t~- chalk du~t to th~ ou~r sur~ac~
of the 3~mpl~ wh~l 24. Th~ chalk du~t i~ pro~ d ~o control t~ 3ur~ac~ condition o~ th~ int~r~ac~ b~ween 25 th~ 3~npla wh~l 24 an~ th~ grind~ton~ 20.

~ th~rs i~ ln~uffici~nt du~ting, an o~ly lay~r o~
de~radQd sampl~ ~at~rial will lik~ly build-Up on t~
abrading sur~ac~ o~ th~ grind~ton~ 20, and thu~ d~cr~as~
th~ rat~ o~ a~r~ion o~ th~ ~a~plQ wh~sl 24. How~v~r, ir thar~ is too ~uch chalk du~t, thQ du~t can pr~v~nt ~f~ctiv~ contact b~twe~n th~ sa~pl~ who~l 2~ and tha grindston~ 20 and, likewise, d2cr~3~ tho r~t~ of abra~ion o~ th~ 5a~pl- wh~l 24. Th~r~gor~, th~ chalk stick 46 is pr~rably lightly ~ngag~d with th~ rubber band 54, to maintain a thin fil~ o~ chal~ du~t b~tween thQ sample wheel 24 and ~rindstone 20. Tha forc~
exerted by ~h~ dust tran3~er wheal 40 again~t the sample wheel 24 i~ controlled by a counterweight 56, as shown in Figure 2. The counterweight 56 is connected to thQ
dust transfer wheel 40 by a cord 58. Th~ cord 58 is mounted ovar a irst pulley 60 and a second pulley 62, both ~upported from the cabin~t 12 above th~ framQ 18.

The apparatus 10 furthQr compri~ ev~ral heater~, shown typically as 64 in Fi~ur~ 1. Th~ heat~r~ 64 ar~
preferably electric heater~, ~nd ar~ ~ountQd within thQ
cabin~t 12 to heat the int~rio~ o~ the cabin~t.
Thermocouples, shown typically as 65, aro al~o mounted within the c~binet 12. The th~r~ocoupl~s 6S are coupled to the heaters 64 by wir2s 66, to control the operation of the heater3, and thu~ maintain a d~ir~d tempera~ure within the cabinet 12. BecausQ ~h6 r~lativ~ w~ar rate can change with tire running temparatures, th~
temperaturQ within the cabinet 12 can b~ ad~us~d (along with th~ weights o~ the count~rw~ight~ 29) to a~f~ct thQ
d~gr~ o~ abras~on by th~ grindstonQq 20 again~t th~
samplo wh~ls 2~.

Turning to Figure~ 4 throuqh 6, th~ dxi~æ modul~ 16 of ~5 th~ apparatu~ 10 i3 shown in ~urth~r d~t~il. Th~ drive modulQ 16 comprl~ a driv~ modul~ fra~el 68, wh~ch i~
gen~rally U-~hap~cl, a~ shown in Figur~ 4. A ~irst drive shaft 70 i~ ~ournaled by beaxing support~ 71 to th~
back, top end o~ t2~ drivQ modul~ ~ra~ 6a. ~ ~c~nd 30 d~iv~ sha~ 7~ is journaled to thQ ~ron'c o~ th~ ~riv~
modul~ ~ram~ 68 b~low th~ ~irst dr~v~ sh~ft 70, by b~aring supports 73. A pulley 74 1~ y~d to th~ ~irs driv~ sllaft 70 bQtw~en 'che driv~ odul~ ~ra~ 6~ and the ad~ acent te~'c station 14 . A drive b~lt 76 i~ mounted ~5 over th~ pulley 74, and is driv3n by an ~l~ct~ic motor 77 to d~iv~ th~ ~ir~ driv~ sha~t 70. A~ ~own in 3 ~

Figure 1, the first drive shat 70 1~ coupled to th~
second sample wheel drlve shaft 28, to drive the ~amplP
wheels 24.

S Tha drive module 16 further comprise~ a first gear 7a keyed to the drive sha~t 70, a~ shown in Fisura 5. A
gear ~ramQ 80 i~ journal~d about thQ ~r~t drive shaft 70 ad~acant to the first gear 78, ~y bearlng 3upport~ 82 and 84. The gear fram~ 80 extend~ outwardly ~ro~ th~
drive shaft 70 toward the front end oS thQ ~ram~ 68, as shown in Figure 6, and is pivotabl~ about th~ drlv~
sh~ft 70. The drivQ module 16 ~urth~ compri~e~ a s~cond gear sha~t 86, which is cpaced inw~rdly ~ro~ the drive ~ha~t 70, and jouxnaled to th~ ga~r ~ra~ 80 by 15 b~3aring support3 81, as showTI in ~ 'Q 5. A ~3econd.
gear 88 is k~ysd to eh~ fr~ Qnd o~ th~ ~cond g~ar shaft 86, and i~ di~ension~d to m~sh with th~ fir3t gear ~8.

20 T~Q driY~ ~odule 16 ~urth~r co~pr.is~ a thlrd gear shaft 90, spac~d ad~ac~nt to th2 s~cond g~ar ha~t ~6, and journaled to th~ }re~ end o~ th~ g~a~ ~ra~ 80, as shown in Figure~ 4 and 6. A third gear 92 ~ yed to the fr~ ~nd oP tha third gear shaft 90, and is located and dimansion~d to mesh with th~ ~cond g~8r 88, as shown in Figur~ C. A ~ourth gear 94 is k~y~d to th~ ~r~ end o~
th~ t~ird ~ear sh~ft 90 and spac~d apart ~ro~ th~ t~ird gear 92, a~ shown in Figure ~. A g~r nut 96 i~
thr~aded to th~ fre~ end o~ th~ g~ar shaft 90, to lock th~ ~ourth gear 94 onto t~ sha~tO As shown in Figure 4, th~ out~id~ surfac~ of th~ gear nut ~6 i~ knurl~d so that the qear nut can be manually thr~ad~d to tha shaf~
90. Th~ ~ourth gear 94 can thu~ bQ e~ily re~oYed from the gear shaft 90 and replaced by a di~r~nt ~iza gear ~5 to c~an~ tha gQar ratio betwQen the ~ir~t d~iv~ shaft 70 and t~Q s~cond driv~ shagt 72, a~ will b~ d~cribed ~ 3'-furt~er ~elow.

T~e drive module 16 ~urther co~prise~ a fi~th gear 98 keyed to the second drive shaft 72 and located immediately below the fourth gear 94. As ~hown in Figures 4 and fi, the fifth gear 98 is dimen3ion~d and located to mesh with thQ fourth g~ar 94. The ~ifth gear 98 i~ thus drlvQn by the fourt~ gear 94 to dri~e ths sacond drivs ~ha~t 72. Tha s~cond drivQ sha~t 72 is in turn coupled to the grind~ton~ driv~ Rh~ft 22, a~ ~hown in Figure 1, o driv~ thQ grind~ton33 20 o~ th~ te~t station~ 14.

~ r~taining plat~ 100 i~ ~ounk~d to th~ front ond oS the driv~ ~odul~ fraM~ 68, and Qxt~nd~ upwardly ad~acsnt to the fre~ end of tha gear frau~ 80. The retaining plate lO0 defines a plurality o~ round holQ~ 102 ~xtending therethrough, as shown in Figur~ 4~ T~ gear ~ram~ 80 also d~fina~ a hole in its ~re~ snd 104 (shown in phanto~), which ha~ a dia~et~r di~n~ion~d about the sa~a ~ize a~ tho dia~tor o~ aach hol~ 102. A~ shown in Figur~ 6, t~ driv~ ~odul~ 16 ~u~ther COI~prlSQ~I a rctaining pin 106, which i~ dl~on~ion~d to ~it through any Or t~ hol~ 102 and into th~ hol~ 104 o~ th~ gear framQ ao. Tho retaining pin 106 1~ coupl~d to ~
rQtaininq pl~t~ lO0 by a cord 108. Th~ ga~r ~ra~a 80 is thU8 lock~d r~lativo to the r~t~ining plat~ lO0, by in3erting th~ r2taininq pin 106 through on~ o~ t~ holes 102 and into th~ hole 104.
The gear ratio between the ~ir t driva ~ha~t 70 and the s~cond drive ~haft 72 and, ther~for~, ~h~ ratio o~ the velocity of tho sa~ple wheel 24 to th~ velocity o~ the grindstone 20, i~ adjustabl~ by U~ing di~r~nt iZe gear~ for th3 fourth gear 94. Th~ fourth g~ar 94 is replaced by re~oving th~ gear nut 96 and pivoting ~he ~ ~ 3 ~

gear fram~ 80 upwardly about the driv~ shaft 70. The fourth gear ~4 i~ thus moved out o~ engag~m¢nt with the fifth g~ar ga. ThQ fourth gear 94 i~ then pulled of~ of the sha~t ~0, and replac~d by a new gear 94 that i~
loc~ed onto th~ end o~ tha ~haft 90 by tha gear nut 96.
Onc~ the new fourth gaar 94 is lowered into ~ngag~ment with the fi~th gear 98, ths gaar fra~e 80 i8 locked in plac~ by ins~rting tha pin m~m~Qr 106 through th~
appropriat~ hol~ 102. The hol~ 102 ln turn dir~ct~ tha fre~ end o~ th~ pin m~bQr 106 into thQ hole 104 of tha gear ~ramo.

A~ shown in Fisur~ 5, th~ driv~ m~dulQ 16 also comprises a first dis~ 110 ~Qyed to th~ ~lrst driv~ haft 70, lS ad~ac~nt to the le~t leg o~ ~h~ driv~ modul~ frame 68.
A first optical ~en~or 112 i~ mountQd to th~ drive module ~ra~e 68 ad~acent to th~ flr~t dl~k 110. T~e optical ~nsor 112 d~tect~ thQ rotational ~p~Qd and counts t~Q r~volution~ Or thQ ~ir~t disk 110 and first 20 drivo ~haft 70 and, theregor~, th~ s~pl~ wh~ 24.
Ths ~ir~t op~lcal sen~or 112 g~n~rat~ output ~lgnals to a ~ir~t ~lgital dlsplay 11~, sho~n in Figur~ 1, which display~ tho v~locity and 'ch~ nu~r o~ r~volu~ion~ Or th~ pl~ w2~ 2 4 .
Th~ drlv~ ~odulo 16 i~urth~r co~pris~ a. s~cond d~sk 116 k~yod to th~ s62c:0nd driv~ shaft 72, ad~c~nt to th~ left leg o~ tha d~ivo D~odule fram- 68. A ~cond optical s~n~or 118 i~ mounted to th~ driv~ Jaodul~ ~r~ 8 30 ad~acQnt to tha sacond di~k 116. T~ao ~cond optlcal slansor 118 det~ct~ th~ rotational v~loclty and counts thQ rQvolu'cion-~ o~ tho second disk 116 and ~cond drive sha~ 72 and, thererore, the grinds'con~ ~0. T~e~ second s~n30r 118 g~n~ral:e~ output qignal~ 'co a digital display 35 120, shown in ~ 1, which di~play. 'che~ ~lo::iky and thQ number of r-volutions o~ th~ g~nd~ton~ 20.

In tll~ operation o~ th~ apparatu~ 10, the dri~e module 15 driv~ thQ grind~tone~ 20 and ~ho ~a~pl~ wheels 24 o~
the test tation~ 14 . The -~ampl ~ whQ3~1s ar~ thu~
abraded against th~ re~pectiva grindstones to provide S abra~ion data ~or the compolmd of th~ 3a~pl~ whe~
When tha electric motor 77 i~ started, th~ pulley 74 of th~ driv~3 module 1~ driv~ thQ :~irst driv~ ha~ 70.
Th~ firct drivo shaft 70 driv~ the second sa~pl~ wheel driY~ shaft 28 which, in t.urn, driv~ ~hQ second 10 sproeket 32 oi~ e~eh te~t station 14. Each s~cond ~proek~t 32, thar~forQ, rotatas th~ resp~etiv~ e~a~pl~
wl~Qal drivo b~lt 34, whieh in turn rotat~s~ th~ ~ir~
-qproeXst 31, and driv~s th~ rQsp~etivo ~a~pl~ whe~l 24.

15 Th~ el~etrie ~notor 77 al~o rotate~ th~ ~rind~ones 20 by driving th~ first drivQ ~haft 70, whleh drive~ ~h~ ~irst g~r 78. Ths ~ir~t g~r 78 driv~s th~ ~Qc:ond gear 88 whieh, in turn, driva~a th~ third gear 92 and fou~h gear 94. Th~ fourth gear 94 drivQ~ th~ ~ifth gs~ar 9~ which, 2 0 in turn, drlva~ t~o s~corld drivQ $ha~t 7 2 . ThQ driv~
sha~t 72 i~ couplQd to th~ qrlnd~ton~ driv~ ~haft 22 which, in turn, rotatably driv~ tA~ grind~ton~ 20 o~
tho t~t ~tations 1~. A~ indicat~d by th~ ar~ow~ shown in Figurl 2, t~ . ampl~ whe~l~ 2 4 and grind~ton~ 2 0 are 25 rot~tably drivQn in oppo~ito dir~ction~ cau~ all of t2~ ~pl~ wh~ 24 ar~ driv~n `Dy t~ ~ir~ drivo shaft 70, all o~ t~ mpl~ wh~Ql~ ~r~ driv~n ~t th~ ~as~--rotation~l ~p~d . Likewis~, b~cau~ th- grind3ton~ 2 0 ar~ all drlv~n by th3 ~econd driv~ sha~t 72, all of the 3 0 grindston~s ar~ driv~rl at thQ ~aDI~ rotatlonal ~p~d .

Th~ rat~ o~ abra~ion of each sampl~ wh~l 24 at ~ach to-t ~tatlon 14, is sot by controlling thQ ratlo o~ th~
linsar ~or tan~nt~al) velocity o~ thQ ~aD~pll- wh~ols 24 35 to tho lin~ar (or tang~ntial) v~locity o~ th~

~ ~J ~

grindstones 20, which is r~ferred to a~ the slip value (S). The slip value (S) is defined a~ follcw3:

(l) S = [Vs ~ V~] * 100(%) VS
where Vs i~ the linear velocity of th~ abraded sur~ac~s of thQ sampl~ wheels 24; and VG is the linear velocity o~ ~h~ abrading sur~ace~
of th~ grindstones 20.
The slip valu~ (S) i~ controlled by 3~1ecting an appropriat~ siz~ g~ar ~or the ~ourth g~ar 94.
~re~2rably, the apparatus 10 can be employed with a number of di~ferent siz~ ~ourth gQar~ 94 ~o that tha slip value (S) and, there~orQ, th~ rat~ o~ abra~ion may be ~Qt at incre~ental steps within th~ rang~ o~ about - 30~ to 30~ ~lip.

In a typlcal abra~ion test in accordancQ with the~
25 pr~a~nt inv~ntion, the sampls wh~ 2~ ar~ abr~d~d at ~oY~ral slip values (S) to provldo abr~ion d~t~ under di~erent d~gree~ of abra~ion ~Qv~rity. Prfl~rably, at lea~t two to five ~a~ple wheel~ 24 o~ e~ch t~t coDIpound are abraded. ~owever, ~che apparatus 10 c~n a~rade~ one 30 sampl~ wheel 24 in each te~t ~tation 14 and,~ ~her~fore, up to twelv~ sa~ple wheel~ at on~ ti~. Th~retorQ, saveral di~ferent compounds may h~ abrad~d in t2 apparatu~ 10 at once.

Ths nu~ber of sa~ple wheels 24 abraded for a given compound dep~nds on the discri~inat~on ~uir~d bQtween compound~. For example, i~ two sample wheels are tested, tha deviation from the ~ean i~ u~ually about 3-5%; whereas if five sample wheel are te3ted, the deviation from the mean is usually on the order of about 2-3~.

The diamster and weight of each sample wheel 24 is maasured at the start o~ an abra~ion te~t and after rotation at ~ach specified ~lip valu~, in ord~r to deter~ine the volum~ los3 due o abra~ion. An electronic balanc~ accuratq to about 0.1 mg i~
preferably us~d to wQigh th~ sampl~ wheQl~ 24. Ths mea~ured weight lo~ i correct~d ~or e~apora~ive w~ight loss during t~ test. Th~ correction for ~vaporative weight los~ i dete~ined fro~ the woight chang~ o a dummy sample wheel 24 ~ad~ o~ tha te~tQd compound, which is kept in~ide t~e cabinet 12 but i~ ~ot abraded, as dsscrib~d further below. Th~ dia~t~r~ o~ the sampl~
whaels arQ mQasur~d pr~erably with a la~r ~icro~eter, such a~ tho Zygo las~r micro~t~r, modol no. 1201B, manu~actur~d by ths Zygo Co. o~ ~lddl~iald, Connacticut. Thr~ meAsurem~nt~ aro tak~n at ~ub~tantially ~qual intervals along th~ circu~erance o~
each runner, and the measure~ent used is th~ a~.reragQ of ~5 th~ thrQn m~a~ùr~m~nts taken.

Th~ av~rags vol~na lo~ p~r unit o~ tra~l (cc/c~), or wQar ra~a (W) ot thc runner~ ~or ~ach giv~n compound is calc~llated a~tQr abra~ion at ~ach ~lip valu~. Th~
30 volu~ 1033 (CC~ ig det~r~ined b~d on th~ ~a~ured wQight lo . ~ of each runner (corr~ct~d ba~ed on th~
weight chang~ of th~ corresponding du~ ) and the density o~ th~ co~pound. Th~ trav~l o~ ~ach runner (c;~) at eactl slip valu~ i5 calculate~ by det~ ining th~
35 averag~ o~ th~ runner's diam~t~r ~ ur~nt b~fore abra~ion and th~ ~unn~r' ~ dia~t~r ~asur~DIont aft~r ~ r~ J

--20~
abrasion at that slip value. The average diameter measurement is then used to determine the average circumference of the runner at that ~lip valua. The av~rage circum~erence is then multiplied by the number of revolutions, to dater~ine the travel of the runner (cm) at that slip value.

T~e following equation is then fit to thQ volum~ 10~3 data of each co~pound tested to analyze the data at different slip value~:

(~) W ~ KSn where W i~ t~e wear rate o~ th~ ~ample wh~els 24 ~or each compound:

S i~ th~ lip value as dQ~ined abcvQ in equation (1); and K and n ar~ e~pirically d~t4rmined con3tant~
calculatQd ~ro~ Qguation (2).

A ~aboratory ~ra~ion IndQx (LI) i~ th~n d~t2r~ined for each tQ~to~ compound at each ~lip valu~:

(3) LI ~ Wreferenc~
Wsa~pla where WreferenC~ i~ the wear rat~ oS th~ ~a~pl~ wheels 2 oS the ref@rencs compound: and WSample is the wear rate of the sample sheels 24 of each sampl~ compound.

S ThQre i~ always at lea~t one ampla wheel 24 mad~ of a referenc~ compound which i3 abradQd with thQ other sampla wheels 24. Th~ re~erencQ compound is abraded for comparison to thQ othQr ~ampl~ compound~ te~ted, to det~rmin~ th~ Laboratory Abra~ion Index (~I) as d~in~d in equation (3).

I~ tha e~ct of the te~t compound'~ hardn~s~ on w~ar ratQ i~ to b~ con~id~r~d, th9n eh- ~ootprint arQa o~
contact batwaen th~ abradQd ~a~pla whe~l~ 24 and their re~p~ctiv~ grind~ton~s 20 ar- also ~a~ured. A
footprint is ~Qa~ured by inXi~g 3~v~ral ~sction~ of the abraded sur~ace of a ~pl~ wha~l 24. Th~ sampl3 wh~el 24 i~ mounted in a te~t station 14 and a he~t o~ paper is plac~d ov~r the abrading 3ur~ac~ og th~ rQ~p~ctiYe grind~ton~. Th~ inX~d ~ur~aco~ Or th~ sa~pla whe~l are then low~r~d into engag~Qnt with th~ heet o~ paper, under th~ ~oro~ o~ th~ re~p~cti~Q counterw~ight 29. ~he surfac~ ar~ of tho inkod ~ootprint3 on th~ paper are th~n m~sur~d, preferably with a Kontron I~age Analysis Sy3tQ~, ~od~l no. KAT 386, ~anu~actured by the xontron Co. o~ Mount~in ViQw, Cali~ornl~.

Tho footpr~nt 3r~a~ ara pr~f~rably ~surgd wh~n ~ha initial wcight~ and diameter~ o~ thQ ~a~plQ wheQ1~ 24 ar~ m~a~ur~d at th~ start o~ an abrasion t~t. Th~
Laboratory Abra~ion Index (LI) can then b~ adjusted based on th~ ratio o~ the avQraqQ ~oo~print ar~a o~ the ~ampla wheel o~ th~ test co~pound, to the ~ootprint are~ o~ t~ sa~pl~ whe~l or whecl~ o~ ~h~ r~r~nc~
compound.

.

d -22~
T~rning to Figure 7, the order of abrading the sa~ple wheels 24 in the test stations 14 in accordance with a method of th~ present invention, is illustratad schematically. Several group~ o~ sampla whsQl~ 24 ar~
compression molded, as de~cribed above, each group being molded from a difSer~nt test compound. Som~ of the sample whe~1~ 24 of each compound are U~Qd a~ runnera, which are abradsd again~t th~ grind~ton~ 20. Ths other ~amplQ wheels 24 are us~d a~ dummies, which ar~ o~ly abradad during a conditioning gtep, and ar~ simply ~aintained within th8 cabin~t 12 whilo abradlng t~
runn~r~ during th~ test. Th~a cora 2S o~ ~a h ~a~pla wh~el 24 (both runners and dum~iP~) is ~arked with a num~cr 50 that each sa~pla whe~l can bc id~nti~ied throughout ~he test.

The number of dummie~ per group o~ runner~ i~ preferably determined a follow~: iS onQ batch O~ a compound is tested, there are four runner~ and one dum~y: iS two 20 batchQ~ of a giv~n co~apound ar~ te~t~d (replicatQ
batcha~), ther~ ar~ thre~ runnors and on~ dum~y ~or each batch: and i~ thre~ batch~ o~ a given co~pound ar~
tested, t~r~ ar~ two runn~r~ and onQ du~y ~or each batch. Pro~Qrably, an even numb~r o~ sa~plo wheels 24 2S o~ o~ch ~iv~n compoun~ i~ tested: on~-hal~ o~ thQ sa~ple wh~ 2~ can b~ abraded on th~ t~t ~atlon~ 14 on the l~t bank of th~ apparatus 10, and th~ oth~r hal~ can be abradQd on tA~ t~t station~ 14 on th~ right bank.

Tho sampl~ whe31s 24 are placad on spindle~ in randomized ordar, with six whe~ls p~r spindl~, as indicated in Flgure 7. Th2 dummy whe~l~ ar~ placQd on separate spindl~ (not shown). Figur~ 7 illustra~es only ~ix of th~ test station~ 14, which ~ay b~ sither 35 tho ~ix lsft bank or ~ix right bænk t~t stations.
How~ver, th~ runnor~ for ~ho oth~r bank o~ ations 14 (not shown~ are abraded in thQ same manner as those illustrated in Fiqure 7.

The sample wheels 24 (both runners and dummies) are th~n conditioned by placin~ all of the spindles in an oven at about lOO'C for about 24 hour~. The cabinet 12 i~
preheated to about 49~C, and upon remo~al ~rom tha oven, th~ spindle~ are then plac~d within the haated cabinet 12 ~or about 30 minute~. The runner~ and dummies ar~
then each mounted in a re~psctiv~ ta~t station 14, and conditioned for a~ut 10,000 r~volution~ at 860 RPff, with th~ temperature within thQ cabinet 12 set at about 49 C. ThQ fourth gear 94 is ~ized ~o that th~ lip value ic about 7~.
After conditioning, the wheQls ar~ pe~itted to cool to room ~emperature, however, all wheel~ (runn~r~ and du~mies) are ~aintained at th~ ~a~ temp~rature throughout the te~t. Th~ abradlnq surfaces o~ the grindstones 20 ar2 then cleaned with a wlr~ brush. The cabinet 12 is vacuumed to re~ov~ any loose particle~
collected during the conditioning ~tep. And tha rubber bands 54 on the dust tran~fer whs~l3 40 are replaced.

2 5 The diameters o~ thR runners are then measured, a~
d~crlbed above. The weight o~ ~ach o~ tha ~ample wh~ls 24, both runner~ and dwnmi~ tA~n ~a~ured and recorded to thQ n~arest 0.1 l~tgr Th~ cabirl4~t 12 is then preheated for at least two hour~3 at about 49 c.
All o~ thQ sa~ple wheels 24, both runn~r~ and du~uie~, ar~ then ~eated inside the cabinat 12 ~or at l~a~t 30 minutes .

The runners ar~ then moun~2d on tha r~cpectiv~ sample 3s wheel driv~ shaft~ 26, in t~e order indicated in Figure 7. The fourth gear 94 i9 sized ~o that th~ 31ip value -2~-is about 7%, and the interior of the caDinet 12 is maintained at about 49'C. ThQ runner~ are then abraded for about 15,000 revolution~ at 860 RPM. Onc~ the runners are stopped, they are removed from t~e respective test station~ 14 and placed back on the spindles, in th~ order indicated in Fiqur~ 7. ~he spindla of runners i5 then mounted again onto the re~pective te~t station~ 14, in thQ order indicatad in Figur~ 7, and abraded agaln for about 15,000 revolutions lo at 860 RPM. Therefor~; each runner 24 is abrad~d in a new test tation 14 with each abrading ~tep.

When th~ runners are taken o~f o~ Qach test ~tation 14, ~hey arQ ~lipped over and th~n placed on thQ spindle.
The direction oP rotation o~ th~ runner~ i~ therefore revers~d betw~en each succ~s~ive te~t station 14, to avoid errors du~ to variation~ b~tw~en individual te~t stations. ~ach spindle o~ sample wheel~ 24 is abraded on six dif~exsnt tect station~ 14, flipping thQ sampla whe~l~ when ~oving them from on~ st~tion to th~ next.
Each sa~pla wh~ 4 i9 theraforQ abr~ded on each o~ the grind3tone~ 20 on one bank o~ th~ app~ratus 10. A~ter ~ix rotation~ b~tween te~t stations, th~ runn~rs should bQ mount~d on t~ spindles in th~ ~am~ order a~ prior to t~ initial ~un.

Each runn9r i~ th~refor~ abraded ~or a total of about 90,000 revolution~ at the fir~t slip valu~ ~7%). Then, all o~ t~ s~pl~ wheel~ 24 ar~ rQ~ov~d ~ro~ th~
appara~u~ 10 and oooled to room te~p~ratur~. Th~ .
grindstone~ 20 ar~ again wir~ brushed, th~ cabin~t 12 is vacuumed to r~ov~ loose particl~, and tho rubber bands 54 ar~ changed~ Then, the diamet~r o~ each runner, and th~ w~ig~t~ o~ all wh~els, bot~ runner~ and dummies, are again m~a~ur~d and record~d, a~ describ~d abov~.
H~wav~r, th~ av~rag~ weight lo~ o~ gain ~or all th~

dummie-~ of each compound is subtracted from or added to, respectively, the weight 10s8 0~ the runner~ of each of the respective compounds, to more accurately determine the weight loss due to abrasion.

The fourth gear 94 is then changed so that the slip value is about 13%, and the temperature of the cabinet 12 is lowered to about 46-C. The runner3 are then each abraded six more time~ in ix di~ferent test station 14, in the same manner as described abov~. However, during each abrasion step, each runner i~ rotated through about 2400 revolutions at 860 RP~. Therefore, each runner is rotated through a total o~ about 14,400 revolutionq at the second slip value (13~). Then, the lS diameter of ea~h runner, and tha weights o~ both the runners and dum~ies, are measured and recorded, as described above.

The weight loss and dia~eter data at each slip value (S) is then translated into a volu~ los p~r unit o~
travel, ox wear ratQ (W). Tha w~r rat~ (W) can then be fittad into equation (2), and that data can be plotted and analyz~d. ~h~ wear rata (W) da~a i3 al o worked into ~quation (3) to deter~ine ~h~ Laborato~y Abrasion IndRx (~I). Th~ Laboratory Abra3ion Index (LI) can be plott~d as a ~unction of thQ s.lip valu~ (S) to analyze and compar~ the abrasion re i~tanc~ o~ th~ co~pounds te-~ted.

In another method of the pr~nt in~ntion~ th~
apparatus lO i~ employed to ~eaYur~ th~ irr~gular wear re3i-~tanc~ of tir~ æread compound3. In on~ ~x~ple, thre~ di~ferent tire tread comp~und~ ar~ i~ultaneo~sly abraded in th~ apparatus 10, in the sam~ ~ann~r as described above. However, thQ thr~ co~pound~ are succe3~ive1y abra~sd at thre~ diXf~r~nt ~lip va~ue~, as opposed to the t~o slip valu~ described above.

The three slip value~ are 7~, 13~ and 21%. The tire tread co~pounds are thus abraded under relatively low, medium, and high levels of abra~ion s~verity, respectively. However, at the third slip value (21%), each runner is rotated through about 2,000 r volutions at 860 RPM with each re~pective grind~tone. Tharefore, each runner is rotated throuyh a total of about 14,400 revolution~ at the tAird ~lip value (21~).

The three di~ferent tire tread compound~ each contain a different typ~ of carbon black, and ar~ labeled a~ CBl, C32 and CB3, respectively. Th~ calculated results based 15 on tho data collect~d in abradiny the thre~ group~ of ~ample wheels 24, are summarized in the table below:

Wear Laboratory Wear Laboratory Rate (W) A~ra~ion Rat2 (W) Abrasion 20 (cc/c~) Index (LI) (cc/c~ Index (LI) 7~ slip 7% ~lip 13% ~liP 13~ slip CBl 4.56 E-8 100 2.42 E-7 lOo C32 4 94 E-8 92 2.45 E~7 99 25 C33 4.61 E 8 98 2.48 E-7 98 Wcar Laboratory Rata (w) Abrasion (cc/c~) Index (~) 21~ ~lip 21~

C31 ~.45 E-7 100 CB2 6.43 E-7 131 CB3 7.10 E-7 119 The CBl co~pound i3 a reference co~pound, and is abrade~
for compari~on to the otl~er compound3 tested.
Th~reforQ, th~ Laboratory Abraqion Index ~LI) ~or the 3 ~

CBl compound is 100.

~s shown in the table, the wear Rate (W) incr~ases with increa ing slip values for all three compounds.
However, the important feature of the data is that the CB~ compound demonstrates a signi~icantly higher Laboratory Abrasion Index (LI) than doe~ either the c8 or CE33 compounds at th2 highe~t level Q~ abra5ion severity (21% slip). At thQ 7% and 13% ~lip valua~, on the other hand, the Laboratory Ahrasion Index (~I) of the CB2 compound i~ much clo~er to that o~ the C~l and CB3 co~pounds. Therefore, the te~t re~ults indicate that the CB2 compound exhibits better abra~ion resistance than does the CBl or CB3 compounds under hi~h severity abrasion conditions. ~ccordingly, the CB2 compound will likely exhibit better irregular wear resistance than either the C81 or CB3 compounds.

one advantage of the apparatus and method o~ the present invention, is that thQ invention can be employed to solve irregular wear proble~ with ~xisting tires. For example, i~ a tire with an existing tr~ad d~sign turns out to hav~ an irregular wear proble~, th~ apparatus and method o~ th~ present invention can bo employed to ~ind anoth~r tire tread compound, or anoth~r type of carbon blacX to b~ usad in a tirQ tread co~pound, that will exhiblt b~tt~r abra~ion re~istanc~ at high s~verity level~ of abrasion.

~nown apparatus, on the other hand, which do not have the ability to precisely deter~ino abrasion resistance at both high and low severity leval3 of abrasion, woul~
likely not be helpful in pointing to th~ tir~ tread compound to solve the irregular wear proble~. Indeed, in the exampl~ de~cribed above, the known apparatu~
would li~ely indicate that the CB~ comp~und, C8 ~3~

compound, and CB3 compound exhibit substantially the same abrasion resistance when, in fact, the abrasion resistance of the CB2 compound is substantially better at higher lPvels of abra~ion severity.

.,. -. ' ' - .

'.

Claims (17)

1. An apparatus for abrading carbon black containing compounds comprising:
a plurality of rotatably supported abrasive members (20);
a plurality of rotatably supported test members (24);
each test member including a carbon black containing compound, each test member (24) being engageable with a respective abrasive member (20) to abrade the carbon black containing compound;
first means (36, 40, 44) for controlling the surface condition of the interface between each test member (24) and respective abrasive member (20);
second means (77, 16, 28, 70, 22, 72) coupled to the test members (24) and the abrasive members (20) for rotatably driving the test members and the abrasive members; and third means (16) coupled to the abrasive members (20) and the test members (24) for controlling the relative velocities of the abrasive members (20) and the test members (24) to control the degree of abrasion of the test members by the abrasive members.

2. An apparatus as defined in claim 1, wherein the first means includes a plurality of dusting members (40), each dusting member being engageable with a respective test member (24), each dusting member applying dust to the respective test member and, in turn, to the interface between the test member and the respective abrasive member.

3. An apparatus as defined in claim 2, wherein each dusting member includes:
a transfer wheel (40) engageable with the respective test member (24) and a chalk member (44) engageable with the transfer wheel, the chalk member applying chalk dust to the transfer wheel (40) and, in turn, to the respective test member (24) to dust the interface between the test member (24) and the respective abrasive member (20).

4. An apparatus as defined in claim 3, further comprising: fourth means (56) for controlling the force of the chalk member against the transfer wheel (24), to control the amount of chalk dust applied to the transfer wheel.

5. An apparatus as defined in claim 4, wherein the fourth means includes a first weight (56) coupled to the transfer wheel, the first weight being selected to set the force of the transfer wheel against the chalk member.

6. An apparatus as defined in claim 3, further comprising: fifth means (29) for controlling the force of each test member (24) against the respective abrasive member (20) to control the degree of abrasion of the test members by the respective abrasive members.

7. An apparatus as defined in claim 6, wherein the firth means includes a plurality of second weights (29), each second weight being coupled to a respective test member (24), each second weight being selected to set the force of the test member against the respective abrasive member.

8. An apparatus as defined in claim 1, wherein the second means includes a motor (77) and the third means includes a gear member (16);
the second means further including:
a first shaft (28, 70) coupled to the motor (77), the test members (24) and the gear member (16) and a second shaft (22, 72) coupled to the abrasive members (20) and the gear member (16), the gear member being selected to control the velocity of the first shaft relative to the velocity of the second shaft and, therefore, the velocities of the test members relative to the velocities of the abrasive members respectively.

9. An apparatus according to claim 1, comprising:
a plurality of test stations (14) wherein each said station includes a grindstone (20), a sample wheel (24), a dust transfer wheel (40) engageable with the sample wheel (24) and a chalk member (44) engageable with the dust transfer wheel (40); and a drive module (16) coupled to the test stations (14) including a gear assembly (78, 88, 90, 92, 94, 98) to control the relative velocities of the grindstones (20) and sample wheels (24) and thereby control the degree of abrasion of the sample wheels.

10. A method of abrading a carbon black containing compound comprising the following steps:
weighing each of a plurality of sample members, wherein an outer surface of each sample member is made of a carbon black containing compound;
abrading each sample member in rotating engagement with a respective abrasive member to abrade the carbon black containing compound, wherein the velocity of the sample members relative to the velocity of the abrasive members defines a first slip value;
abrading each sample member in rotating engagement with a least one other abrasive member at the first slip value;
measuring the loss of the carbon black containing compound from each sample member at the first slip value;
abrading each sample member in rotating engagement with a respective abrasive member at a second slip value;
abrading each sample member in rotating engagement with at least one other abrasive member at the second slip value; and measuring the loss of the carbon black containing compound from each sample member at the second slip value; the slip value being determined by the difference between the velocity of each sample member and its respective abrasive member divided by the velocity of the sample member.

11. A method of abrading a carbon black containing compound as defined in claim 10, wherein the first slip value is within the range of 5 to 9%; and each sample member is rotated within the range of 10,000 to 20,000 revolutions with each abrasive member at the first slip value;
the second slip value is within the range of 9 to 17%; and each sample member is rotated within the range of 1000 to 5000 revolutions with each abrasive member at the second slip value.

12. A method of abrading a carbon black containing compound as defined in claim 10, further comprising the following steps:
abrading each sample member in rotating engagement with a respective abrasive member at a third slip value;
abrading each sample member in rotating engagement with at least one other abrasive member at the third slip value; and measuring the loss of the carbon black containing compound from each sample member at the third slip value.

13. A method of abrading carbon black containing compounds as defined in claim 12, wherein the third slip value is within the range of 17 to 30%; and each sample member is rotated within the range of 500 to 4500 revolutions at the third slip value.

14. A method of abrading a carbon black containing compound as defined in any one of claims 10 to 13, further comprising the following step:

controlling the ambient temperature of the sample members and abrasive members within the range 40°C -55°C to control the degree of abrasion of the sample members by the abrasive members.

15. A method of abrading a tire tread compound to measure the irregular wear characteristics of the compound, comprising the following steps:
weighing a plurality of test members, wherein an outer surface of each test member is made of a tire tread compound to be abraded;
rotating the outer surface of each test member in engagement with an abrasive member to abrade the tire tread compound, the relative velocities of the test members and the abrasive members defining a first slip value;
weighing each test member to measure the loss of tire tread compound at the first slip value;
rotating the outer surface of each test member in engagement with an abrasive member to abrade the tire tread compound, the relative velocities of the test members and the abrasive members defining a second slip value, the second slip value causing a higher level of abrasion severity than the first slip value;
weighing each test member to measure the loss of tire tread compound at the second slip value;
rotating the outer surface of each test member in engagement with an abrasive member to abrade the tire tread compound, the relative velocities of the test members and the abrasive members defining a third slip value, the third slip value causing a higher level of abrasion severity than the second slip value; and weighing each test member to measure the loss of tire tread compound at: the third slip value, the loss of tire tread compound at the different levels of abrasion severity thus indicating the irregular wear characteristics of the tire tread compound, each slip value being based on the difference between the velocity of the test members and the velocity of the abrasive members, divided by the velocity of the test members.

16. A method of abrading a tire tread compound as defined in claim 15 wherein:
the first slip value is within the range of about 5 to 9%; and each test member is rotated within the range of 10,000 to 20,000 revolutions with each abrasive member, the second slip value is within the range of about 9 to 17%; the third slip value is within the range of about 17 to 30%; and each test member is rotated within the range of 1,000 to 5,000 revolutions with each respective abrasive member at each of the second and third slip values.

17. A method of abrading a tire tread compound as defined in claim 16 wherein each test member is rotated in engagement with a plurality of respective abrasive members at each of the first, second and third slip values.