Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
.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
5--
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
--10--
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
--11--
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~
-12-
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
-13-
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 ~
-14-
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 ~
-18-
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
--19
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
3S
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
--23--
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
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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~
-28-
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.
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