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Патент USA US2404584

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July 23, 1946.
‘J. wjLlsKA ET AL
2,404,584
BENDING MODULUS TEST APPARATUS
v
IX
Fiiled Dec. 50, 1944
Z'Sheets-Sheet i
dorm w. LISKA
AND
'
.
FRANK EGROVER
GHQ/WW
July 23, 1946. j
J. w. LISKA ETAL '
‘2,404,584
I BENDING MODULUS TEST 'APFARATUS
Filed ‘Dec. 39, 1944
2 Sheets-Sheet 2
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(JOHN W. LISKA
AND
‘
FRANK 5.GROVER
‘
W
Patented July 23,1946
2,404,584 ~
UNITED STATES PATENT ‘OFFICE
' 2,404,584
BENDING. MODULUS TEST APPARATUS
John W. Liska, Stow, and Frank S. Grover, Akron,
‘ Ohio, assignors to The Firestone Tire & Rub
ber Company, Akron, Ohio, a corporation of
Ohio
Application December 30, 1944, Serial No. 570,634
5 Claims. (Cl. 73—15.6)
1
This invention relates to test apparaus for de- _
2
turntable of the apparatus at the’work-testing
station thereof, and. a test sample of the work
termining the bending or de?ection character
istics of various plastics and elastomers, includ
thereon;
v
ing Hevea rubber and various synthetic rubber
Fig. 3 is a fragmentary front elevation of the
like compositions, and more especially it rel-ates 5 apparatus, parts thereof being broken away and
to apparatus for obtaining such data at determi
in section;
’
nate reduced temperatures.
,
Fig. 4 is a side elevational detail of the dial
The invention is of especial utility to rubber
gauge of the apparatus; and
.
‘I
technologists who seek to determine the service
Fig. 5 is an elevational detail, on a larger
ability of various elastomers for particular appli 10 scale, of the loading foot of the gauging mecha
cations under conditions of low temperature, al
nism.
,
though the apparatus may be used for the same
Referring to the drawings, there is shown a
purpose at temperatures as high as room tem
‘cold cabinet or refrigerator that is designated as
perature without sacri?cing all of the advan
a whole by the numeral Ill. The refrigerator per
tages thereof. Complete servicability analysis of
15 se may be of any known or preferred construc
an elastomer requires the determination of both
its bending and its brittleness characteristics, but
tion, the cold coils, the compressor, and a there
mostat for regulating the temperature of the in
the present invention relates solely to apparatus
terior of the refrigerator being omitted since they
for obtaining data from which Young’s modulus
constitute no part of the present invention. The
of elasticity may be determined.
1
20 refrigerator includes the usual cold chamber I l
The literautre reveals a considerable diversity
' that is accessible by means of a hinged door I2,
in test methods employed to determine the ef
and supported in the lower part of said chamber.
fects of low temperatures on the physical prop
upon a'plurality of legs l3, I3 is a base plate M.
.erties of rubber and rubber-like compositionsi
The latter is formed with an axial bearing hous-l
Among those who havepublished papers on the 25 ing I5 that carries vertically spaced apart bear
subject is Koch, E. A.,‘Rubber Chem. Tech., 14,
ings I6, I6 that receive the axial stem or stub
799 (1941); Kautschuk, 16, 151 (1940). Koch’s . shaft I‘! of a horizontally disposed turntable l8.
test is one of the few in the literature in which a
The turntable is arranged to be power driven, and
basic, physical property of the material under
to this end the turntable stem I‘! has a short
test-is measured. Largely because of this feature, 30 shaft l9 mounted therein and projecting down
the principles of Koch’s test were adopted as the
wardly therefrom, the lower end of ‘ said shaft
basis for the method employed in the low-tem
being provided with a bevel gear 20' that is
perature test that is practiced by means of the
meshed with a bevel gear 2| of- the samersize.
apparatus of the invention.
The gear H is mounted upon a horizontal shaft
The chief objects of the invention are to pro- '
22 that is journaled in suitable bearing brackets
vide improved apparatus of the character men
23, 23 that are mounted on'the bottomiace'of
tioned and for the purposes set forth; to provide
base plate l4, said shaft 22 extending toward a
apparatus of the character mentioned wherein a
lateral wall of the refrigerator and terminating
large number of test samples may be maintained
interiorly of the chamber I l in a coupling “that
atv uniform temperature; to provide against trans
mission of heat to the interior of the apparatus
by way of elements of the apparatus that neces
sarily extend through the wall thereof; to obviate
the accumulation of frost on relatively moving
operatively connects it to a driving shaft 25. The
latter extendsthrough the wall of the refriger
ator 10, being journaled in bearing bushings 26,‘
23 that are mounted in said Wall at‘ opposite ends
of a bore or aperture 21 that extends through
‘parts of the apparatus; to provide work-engag
said wall, said aperture being substantially larger
ing elements of such shape that indentation
in diameter than said shaft 25 ‘to provide ample
(penetration) into the work piece or sample is
clearance therebetween. Exteriorly of the refrig
reduced to the minimum; and to provide means
erator the shaft'25 has a sprocket 28 mounted
for adjusting the dead-weight load of the load
thereon that has driving connection with the
applying element of the apparatus. Other ob 50 shaft through suitable friction mechanism 29.
jects will be manifest as the description proceeds.
Trained about the sprocket 28 is a chain 30 that
Of the accompanying drawings: 1,
Fig. 1 is a perspective view of the test appa
also is trained about a sprocket 3| on the drive
shaft 32 of a speed reducing ‘device 33, the‘latter 7
. .
being operatively connected to an electric motor
Fig. 2 is a fragmentary radial section of the 65 34 and both being supported upon a suitable
ratus constituting the invention;
2,404,584
3
.4
table 35, which also may constitute a support for
arrangement being such that the'handwheel may
the refrigerator. In operation the motor 34 may .
be turned until it abuts said washer, whereupon -
be constantly driven, although the turntable [3
further turning will lift the loading rod 49 rela
tively of the sleeve £33. Turning of thehandwheel
in the opposite direction lowers the rod :19. The
rod 839 is composed of Bakelite, and has its medial
portion of reduced diameter to provide a substan
tial space 52 between itself and'sleeve 48. Any
moisture that enters saids'pace 52, from the ex
terior of the refrigerator, will‘condense and form
frost somewhat below the upper end thereof.
The end portions of the rod 69' are of such size
as'to have sliding" ?t in the sleeve 43, the latter
thus constituting a bearing for the rod, the bear
ing surfaces being spaced from the frost zone,
will be'stationary while tests are being made, as
presently will be described, the arrangement be
ing possible by means of the friction connection
29 between said motor and‘the shaft 25. Theme
ture of providing substantial clearance between
‘ ‘the shaft 25 and wall of the aperture 2‘! enables‘
moisture to condense therein without impeding .
the driving of said shaft.
Mounted. upon thetop of turntable i3 is a plu- ‘
rality of test-sample supports " 31, 3?, herein
shown as thirty in number. 'lil'ach'ofrr-saidsup-v
ports is composed of metal and is formed at op
posite ends with respectiveraised ribs 38 upon
which a test sample 39 of rubber or other elas-;
above and below the same, so that the presence of
frost will not influence the operation of the gaug~
ing mechanism.
tomer is positioned for testing. The ribs 38 are,
' The lower end of the rod 49 carries a loading
rounded so as to reduce penetration into the sam
ple 39 during a test.
foot 54 that is adapted to engage the test sam
The test samples are accu- -
ples. As shown in Figs. 2 and 5, the loading foot
has a tapered sample-engaging extremity that is
of the same Width as the sample, and is rounded
ratelyformed to determinate, dimensions, a size
of 1, inch wide and 2.25 inches long being found
satisfactory. In thickness the samples mayvary
from RIO-6A0 inch as desired.
'
on the same radius as the ribs 38 to reduce pene
'
. The samples 35' are tested in succession at a
tration into the sample.
determinate point or station in their orbit, and
the loading foot is located within the 1ower end
The upper portion of
means is provided forholding the‘ turntable sta_
portion of the sleeve t8, and is formed with op‘
positely extending ribs 55- that are slidably re
ceived in respective slots 56 in the sleeve, the ar
tion for the testing of each sample. To this end‘
rangement being such as to prevent rotation of
the peripheral face of the turntable is formed
the loading foot 54 and loading rod 49 with rela
with a plurality of recesses 42, 42 that are deter
minately positioned with relation to the, supports
tion to sleeve 48.
31,,and selectively receivable in. said recesses is a
Mounted upon the upper end of the loading rod
detent 43. _ The latter is a sectional structure that
139 is a weight pan 58 upon which conventional
extends through the wall of the" refrigerator it 3: weights 59 of known value may be positioned.
5-0 as to be capable of manipulation from the ex~
The’ weight pan is axially apertured ‘and the
terior. thereof. The ‘end. portion ‘of the detent
weights are radially slotted to accommodate a
.43fthat‘i's' disposed within the interior of the
metal push rod 6t that extends upwardly from
refrigerator is composed of metal, ‘the remainder
the upper end of loading rod 479, coaxially there
4.4 thereof being composed ;ofv “Bakelite” (a 40 with. The upper end of push rod 68 operatively
phenol-eformaldehyde resin)’. The detent is slid-'
engages the lower end of the operating stem 6i
ably mounted, for longitudinal movement in a
of a dial gaugetZ that is calibrated to indicate
sleeve?iti that is mounted in the refrigerator-‘wall,
measurements of one-thousandth of an inch.
tionary and accurately in'proper angularposi
said sleeve being composed of Bakelitewhich is
preferred because of its low thermal conduc:
tivity. The diameter of the metal detent 43 is
substantially smaller than the inside diameter of
sleeve lit‘to provide space in which moisture,
The gauge E52 is adjustably mounted upon an arm
VI
from the top of the refrigerator I0.
dense. 1 The; detent is pulled outwardly when it -.
is desired to ‘index the turntable through an
anglei that corresponds to the spacingbetween
adjacent sample supports 3'5, the motor 34 driv
ing‘th'e turntable when the detent is withdrawn‘.
In the testing of the samples 39, after they have 4:
been 'conditioned‘for ajsuf?cientlength' of time
to, reach the temperature desired, a determinate
statioWeight, is imposedupon the sample, midway
60
of the sample then being noted'by means. of, a
gauge. 1 To thisend an elongate‘bearing sleeve
68 of ‘Bakelite is mounted on a vertical axis
through the top of the refrigerator l0, directly
above the orbit of thesamples 39 where said orbit '
is nearest, the front of the refrigerator, the axis
of said 'sleevebeing directly over a test sample
When the turntable is at rest by reason of the en
I
To relieve the test-samples 39 of the dead?
which may’seep in. from the outside, may con,
between the ribs 38. that supportQit, for, a'de‘ter
minate ‘interval of time, the, resulting de?ection
63 that is adjustably mounted upon and projects
forwardly from ‘a standard 64 that rises vertically
weight load vof the gauging mechanism during a
test, means is provided 'fcrlrcounterbalancing most
of said load: To this end' a'metal support‘ 3371s
mounted atop the standard 54, said ‘supporthav
ing a horizontal'top upon which a pairjof agate
bearings $1 are mounted. 'A metal beam 68, is
providedwith a transverse knife'edge 69 that
rests in bearings 67 so that the beam pivots there‘:
on. Adjustably mounted'__upon,the rear. end of
beam 68, is a counterweight ‘It. Mounted upon
the frontend of the beam, 68 isayoke'iL-and
depending from opposite ends thereof are'wire's >
12, 12 that are connected at theirilow'er'ends'lto
the respective ends of a yoke l3igth'a't. is ?xedly
constitutes a lever, and by adjusting the‘ counter.
weight 10 longitudinally thereof. any portiohjbf
the dead-weight‘ load of the ioadingrodlts and
elements carried thereby; may be compensated
gagement of detent 43 withone of the recesses 42
of the turntable. Slidably mounted for longitudi 70 for.A rotary ian'lty is located withinthe" chamber
ll and driven by a suitablemotor (not shown)
nal movement in sleeve d8 isa loading rod 49
located exteriorly of the chamber. The fan is
that is exteriorly threaded at its upperend por
tion, there being a handwheel 50mpunted on saidv
threaded portion. Thereis afmetal Washer 58
positioned upon theupoeneod, of sleevelt?r the
employed to circulate, they air within the chamber
to assure uniformityv of temperatureuinall :parts
therep?
-
-
.
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2,404,584
.6
‘I'I'he'door l2 ‘of: the refrigerator has a window
W bepre-selected to give a defle'ction‘of» less than
11 therein consisting of several panes of glass
with airspace betweehadjacent panes to re
0.025 inch and more than 0.010 inch)‘
' I“ ~
‘ Because of the ?fteen second interval that
duce‘ thermal conduction therethrough. ' The
elapses between the time of application ofthe
window enables the operator-to view the test,
dead load and the time the amount of deflection
and to observe the'temperature of the chamber '
is recorded, the Young’s modulus calculated ‘from '
as indicated by a thermometer 18 located therein.
these data represents what might be termed ‘a
' Mounted upon the base plate 14 are electric
heating elements 80 that are connectedto a
“?fteen-second Young’s modulus” to distinguish
it from the total and the instantaneous, moduli.
suitable source of electrical energy ,by conduc 10 The ?fteen second interval was arbitrarily cho
tors _(not shown). The heating elements are
sen in the interest of accuracy and convenience.
employed when a series of tests is made at pro-r
Because of the rapid movement of (the gauge
gressively increased temperatures.
7
_
needle immediately after application of the load,
‘In order to assure rigidity of the turntable l8
readings could not be obtained accurately until ~
‘during operation, a supporting roller 82 for the 15 at least ten to ?fteen seconds had'elapsed. In .
turntable-is mounted beneath the same at the
_front- thereof, close to the testing station. The
most instances motion of the gauge needle after
?fteen seconds was slow enough to enable rea
roller 82 is suitably journaled upon a stub shaft
83 carried by a bracket 84 that is mounted upon
sonable accuracy of reading. Longer loading
periods would have been unnecessarily time
the base‘plate M.
>
20
consuming.
'
Because of the relatively light loads employed,
Operation
In the operation of the apparatus, the hand
wheel 50 is rotated so as to move downwardly
as the result of the use of the counterweight, in
dentation of the loading foot and support ribs 38
in the samples is small and practically negligible.
against the upper end of sleeve 48‘ and thereby
to lift the loading rod 49 and loading foot 54 25 However, if highly accurate absolute values are
desired, the de?ection (Bi-R0) should be cor
to a somewhat elevated position. Then the Vari
rected by subtracting the contraction of the load
one test samples 39 of selected elastomers are ac
ing rod, and also theidistance the, loading foot
curately placed upon the respective supports!"
and sample supports have penetrated into'the
as the turntable is slowlyturn'ed. The refriger
ator door I2 is then closed, and the fan 75 and 30 sample. This can be determined in the fol
lowing manner: A solid block of material (steel
turntable driving motor 34 are set in motion.
or Bakelite), at least 0.25 inch thick; 1.5 inches
The refrigerating mechanism (not shown) is
long, and 1 inch wide is placed under a second
then put into operation, its thermostat being set
' sample of the same stock of the same thickness
usually at 0° 0. The time required for the cham
and width. ' The procedure hereinbefore _de
ber II, to attain the desired temperature is in
scribed is repeated. The measured de?ection
de?nite and immateriah ‘Experience has indi
R1'—-—Ro’ is‘vthe sum of the amount the loading
cated that the temperature of the interior of the
foot has penetrated into thesample plus the
thickest samples 39 employed lags behind the air
temperature by about 10minutes. An additional 40 amount the loading rod has contracted or bent
10 minute conditioning is given'the samples to
assure adequate temperature uniformity, for the
observation of modulus changes resulting from a
secondgorder transition. Bending de?ection vs.
load observations are thus begun 20 minutes after
the refrigerator air has reached a given tempera
ture.
-
.,
.
laterally under load 'W. Such bending of the
loading rod is determined independently by
measuring the de?ection produced by a given
load with the loading foot resting directly on the
- steel block. This small correction, A, need be
determined only once for a given load and load
ing rod, since it is independent of any sample.
The amount of penetration of the sample sup
Whenmaking a test, the detent 43 is inserted
ports is then calculated by subtracting A from
in. one of the recesses 42 in the perimeter of
turntable [8 to bring the latter to rest, at which 50. Rl'—-R0' and dividing by 2 (since there are two
supporting ribs sustained the loaded sample). '
time one of the samples 39 is directly beneath
the loading foot 54. Then the handwheel 50 is
turned to lower the loading foot onto the center
of the sample and thus to impose a deadweight
load thereon.
Previously the counterweight 10
Young’s modulus can be calculated from the
55
above data by means of the well known beam
has been adjusted so that the initial deadweight
bending formula:
~
load is a mere 55 grams. It is not found feasible
to reduce this initial load to zero, since experi
ence indicates that a small amount of stress is
necessary to overcome the slight tendency of 60 where
some of the samples to warp or twist as the tem
E=Young’s modulus
perature of the chamber H is varied. An addi
tional load W, such as one or more of the weights
‘=load producing a de?ection, d
d=de?ection (corrected) produced by load W
59, is then placed on the weight pan 58. The
total load (dead load plus W) is impressed on 65 l=distance between centerlines of sample
supporting ribs
the sample for ten seconds, following which the
h=width of sample
weight W is removed. Ten seconds later the
h=thickness of sample
reading of the dial gauge 62‘is recorded as R0.
Weight W is then re-applied to the weight pan
After the foregoing procedure has been ‘fol
and allowed to remain for ?fteen seconds. At 70 lowed for all the samples on the turntable IS,
the end of this time the dial gauge again will
the loading foot is raised to clear the samples and
have come to rest in the majority of cases, and
the turntable is again allowed-to rotate contin
the reading is recorded as R1. The difference
uously. The thermostat of the refrigerator is
R1-—-Ro is taken to be the bending de?ection pro
then set to -20° C.,Land after this temperature
duced by load W. It is desirable that the load 75 is obtained the testing process is repeated. The Y .
a
2,404,584
7
r
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,,
.
8
entire procedure " is-repeated "at -—40°, C. ‘and’
able with the turntable’to hold‘ it stationary in
_ peraturesi, A double set of readings is thus ob
tained at —40°, —20° and 0° C‘. If a physical '
- 3. In apparatus of the character, described,_the
combination of a refrigerator having a- cold
chamber therein, a support in said chamber for
determinate position against the force or its fric
—60° C. (temperatures decreasingLand-at 5° C.
tion drive, and loading meansoperable from the
intervals back ‘to, 0°’ (temperatures increasing).
exterior‘of'the refrigerator for impressing a de
The heating elements 8% may be employed-'to'exe
>
,_
pedite the, increasing, of the refrigerator‘ tem 5 terminate load upon a test sample. , 1
change resulting from crystallization is contrib
utingto the bending, modulusythe readings at
thesethree temperatures (temperatures increas-v
a test sample,,a bearing sleeve extending through
.the refrigerator Wall above said test sample; a
loading rod extending through and axially slid‘
: - ing) ‘will not agree with the readings made as
thevtemperatures are'lo-wered.
able in said sleeve, saidv rod having a reduced
Because of the
medial portion to provide a space between itself
and the sleeve wherein moisture seeping in from
relatively short time required to’ condition and
test stocks by means- of the vpresent, invention,
crystallization, if it occurs at all, will be negli
gible.
-
outside the refrigerator may condense, meansifor >
applying a determinate load to said loading rod
to de?ect the test sample therebeneath, and
I.
Data obtained in the manner hereinbefore set
means operatively engaging the loading rod for
forth may be presented inthe form of graphs
measuring such de?ection.
showing the change in Young’s modulus as a
function of temperature.
'
h
20
The apparatusv is relatively simple in construc
tion,- is e?icient, accurate, andrelatively rapid
in operation; it avoids the necessity for em
ploying relatively thick test samples requiring
high initial load; and achieves the other objects
set out in the foregoing statement of objects.
test sample, a bearing sleeve extending through
the refrigerator wall above said test sample‘, a
loading rod axially slidable in said sleeve, means
25
on said loading ‘rod for engaging said test sample,
means for effecting condensation of any moisture
in air that may seep'into the refrigerator between
,Modi?cation may be resorted to without de
parting from the spirit of ,the invention or the
scope thereof as de?ned by the appended claims.
What is claimed is:
I
'
.
.
4. In apparatus of the character described, the I
combination of a refrigerator having a cold
chamber therein, a support in said chamber for a
30
- 1. In testing apparatus of the character de
scribed, the combination of a refrigerator having
a cold chamber therein, a turntable therein, sup
ports on said; turntable for stock samples to be
tested, drive means for said turntable'extending
the sleeve and the loading rod before said air
reaches said chamber, means exteriorly of the
refrigerator for applying a determinate load to
the'loading rod, and means for- measuring the
de?ection of the sample-effected byrsaid'loa‘d.
5. In apparatus of the character described, the
combination of . a refrigerator having va cold
chamber therein, a vsupport in said chamber for
a test sample, a bearingsleeve extending through
the refrigerator 'wall above said test sample, a
ary, said detent extendingrthrough the refrigera
loading rod axially slidable in said'sleeve, means
tor. wall so as to be manipulated‘ from the exterior
thereof,;loading means forrimpressing a deter» 40 on said loading rod for engaging said test sample,
saidv sleeve and loading 'rod'being composed of
minate load upon a, stock sample in the refrig¢
non-metallic material of. low thermal conduo- '
erator, and means for effecting andv localizing
tivityto facilitate the condensation of moisture
condensation of. moisture in air that may seep
in the air that may seep into the refrigerator
'into the cold chamber along the elements that
extend through the walls of the refrigerator. ‘ ' M O! 'betweenthe sleeve. and the loading rod before
through the'refrigerator wall, a detent engage
able with the turntable to hold the samestation
2. In testing apparatus of the character de
scribed, the, combinationof a refrigerator having
acold chamber therein, a, turntable in said cham
ber, supports on said turntable for stock. samples
to be tested, a motor exteriorly of the refrigerator, 50
frictional driving means connecting the motor to.
the turntable, a manually operable detent engage
said ;'air reaches said chamber, means exteriorly
of the refrigerator for applying a determinate
load to .the loading rod, and means for measuring
thedeflection of .the' sample induced‘by‘said load. -
JOHN W. ,LIsisAf.
FRANK .s. GROVER.
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