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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 _/I. , 42 21/. n 0.1.. . _ 76I‘ A 9. 21/ 2s’ 22" ‘(23, 15/721 . gm I (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? - - . ,,, ,v i. .. 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 . ,, . 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.