SI9700089A

SI9700089A - Device for testing the resistivity against rolling fatigue of materials with optional interrupts

Info

Publication number: SI9700089A
Application number: SI9700089A
Authority: SI
Inventors: Mitjan Kalin; Jože Vižintin
Original assignee: Univerza V Ljubljani
Priority date: 1997-04-11
Filing date: 1997-04-11
Publication date: 1998-10-31

Abstract

This improved device for testing the resistivity to rolling fatigue of materials provides the possibility of interruptions and later continuation of the test from an exactly defined previous state.- This is not possible with currently known devices. When testing rolling fatigue of materials the surface of the test sample (20) is subject to certain strain and rolling of the test sphere (10) with a certain number of repetitions, while between the specified sphere (10) and the test sample (2) surface (20) a point-to-point fitting is provided. The device includes a not shown driving assembly to which a moving pressuring unit (1) equipped with the test sphere (10) is attached which can be rolled along the test surface (20) of each test sample (2) held by a fastening device (3). The specified pressuring unit (1) is equipped with a limiting panel (14) marking and repeatedly determining at least one end of rolling point of the test sphere (10). Besides the holding unit (3) is equipped with a fastening nest (31) to hold the test sample (2) and along which there are sliding supports (32) inside corresponding grooves (34) with loose fit. They can be fastened in a certain position and by this the involuntary moving along the corresponding groove (34) is disabled

Description

Naprava za preizkušanje odpornosti na kotalčno utrujanje gradiv z možnimi vmesnimi prekinitvamiDevice for testing rolling resistance of materials with possible intermittent breaks

Pričujoča prijava se nanaša na napravo za preizkušanje odpornosti na kotalčno utrujanje gradiv z možnimi vmesnimi prekinitvami, česar doslej znane naprave niso omogočale. Pri preizkušanju kotalčne odpornosti gradiv se po površini preizkušanca pod določeno obremenitvijo in ob ustreznem številu ponovitev kotali preizkusno kroglo, pri čemer je med omenjeno kroglo in površino preizkušanca zagotovljeno točkasto naleganje.The present application relates to a device for testing the resistance to rolling fatigue of materials with possible intermittent interruptions, which prior art devices have not enabled. When testing the rolling resistance of materials, a test ball is rolled over the surface of the subject under a certain load and with an appropriate number of repetitions, with point contact between the said sphere and the surface of the subject.

Namen izuma je zasnovati karseda enostavno in kar najbolj vsestransko uporabno napravo za preizkušanje odpornosti na kotalčno utrujanje gradiv, ki naj bi omogočala preizkušanje kotalčne odpornosti gradiv najrazličnejših preizkušancev, zlasti pa naj bi bile med preizkušanjem omogočene prekinitve in zatem nadaljevanje preizkušanja iz natančno opredeljenega poprejšnjega stanja.The purpose of the invention is to design the simplest and most versatile rolling fatigue testing device of the materials, which is intended to allow testing of the rolling resistance of the materials of various subjects, and in particular during interruptions and afterwards to continue testing from a well-defined previous state.

Znano je (npr. iz tehničnih opisov razpoložljivih preizkuševalnih naprav proizvajalca FAG Kugelfischer Georg Schafer AG), da naprave za preizkušanje odpornosti na kotalčno utrujanje gradiv obsegajo vpenjalno enoto, obremenilno enoto in pogonski sklop. Obremenilna enota je tako zasnovana, da omogoča vpetje preizkuševalne krogle določenega premera v primemo ležišče, v katerem je krogla prostozasukljivo nameščena in s tem prosto vrtljiva v vseh smereh. Razen tega je obremenilna enota zasučna, tako da je ležišče preizkuševalne krogle vrtljivo okoli osi, s čimer je omogočeno premikanje preizkuševalne krogle v določeni ravnini po krožnici vnaprej določenega premera. Še nadalje je obremenilna enota prirejena za izvajanje določene obremenitve, s katero je med preizkušanjem krogla pritisnjena proti vsakokratnemu preizkušancu. Pogonski sklop je zasnovan z ustreznimi pogonskimi in nosilnimi deli, ki pri določeni obremenitvi preizkusne krogle omogočajo vsakokrat ustrezno kroženje preizkusne krogle po površini vsakokratnega preizkušanca, vpetega v vpenjalni enoti.It is known (for example, from the technical descriptions of the available FAG Kugelfischer Georg Schafer AG test rigs) that the rolling resistance testers of the materials comprise a clamping unit, a load unit and a drive assembly. The load unit is designed to allow the test ball of a certain diameter to be clamped into a suitable bearing in which the ball is freely rotatable and thus freely rotatable in all directions. In addition, the load unit is rotatable so that the bearing of the test ball is rotatable about an axis, thus allowing the test ball to move in a certain plane along a circle of a predetermined diameter. Furthermore, the load unit is adapted to carry a particular load which is pressed against the test piece during the test. The propulsion assembly is designed with suitable drive and load-bearing components, which, in the case of a certain load of the test ball, allow the test ball to be circulated adequately on the surface of each test piece clamped in the clamping unit.

Vpenjalna enota tovrstne naprave je prirejena za vpetje preizkušanca in zanesljivo vpetje le-tega, zlasti glede na omenjeno obremenitev preizkusne krogle kot tudi na premikanje krogle po krožnici med preizkušanjem. Zasnovana je iz primernih vpenjalnih čeljusti. Pri obstoječi vpenjalni enoti gre torej predvsem za to, da med kotaljenjem krogle po površini preizkušanca pod obremenitvijo in zaradi krožnega gibanja ne bi prišlo do premikanja preizkušanca ali celo odstranitve le-tega iz vpenjalne enote oz. čeljusti.The clamping unit of this type of device is adapted to clamp the test piece and securely clamp it, especially with respect to the said test ball load as well as to move the ball around the circle during testing. It is designed from suitable clamping jaws. The existing clamping unit is therefore primarily about the fact that during the rolling of the ball across the surface of the test piece under load and due to circular motion, the test piece would not be moved or even removed from the clamping unit or. jaws.

Tovrstna naprava je razmeroma zapletena, vendar v splošnem in ob ustreznem ravnanju uporabnika vsekakor omogoča zadovoljivo vpetje preizkušanca med preizkušanjem kotalčnega utrujanja gradiv. Pač pa je pri mnogih preizkusih zanimivo in potrebno opazovanje stanja preizkušanca po določenih stadijih, etapah preizkusa. Gre predvsem za to, da bi bilo možno ugotoviti stanje preizkušanca po določenem času oz. številu ponovitev obremenitve ter iz tega razbrati določene ugotovitve. V ta namen je med izvajanjem preizkusa potrebno v določenem stadiju (po določenem času ali natančneje po določenem številu obremenitev) preizkus prekiniti, izvršiti opazovanje in potrebne meritve ter potem izvršiti preizkus za naslednji stadij.This type of device is relatively complex, but in general and with the proper handling of the user, it certainly allows a satisfactory engagement of the test subject while testing the rolling fatigue of the materials. However, in many tests it is interesting and necessary to observe the condition of the subject after certain stages, stages of the experiment. In particular, it is possible to determine the condition of the subject after a certain time or. the number of load repetitions, and to draw certain conclusions from this. To this end, it is necessary to suspend the test at a certain stage (after a certain time or more precisely after a certain number of loads), to carry out the observation and the necessary measurements, and then to carry out the test for the next stage.

Pri doslej znanih napravah je bilo opazovanje dogajanja po posameznih stadijih med preizkušanjem možno doseči edinole z več med seboj enakimi preizkušanci, ki so jih drugega za drugim preizkušali do različnih stadijev. Tako so prvi preizkušanec vpeli, ga za določen čas izpostavili kotalčni obremenitvi in torej določenemu številu ponovitev obremenitve, ga odstranili iz vpenjalne naprave in zatem opazovali, premerili in podobno. Zatem so poskus ponovili z drugim preizkušancem in ga obremenitvi izpostavili npr. za ustrezno daljši čas ter s tem zagotovili toliko večje število ponovitev obremenitve. Tak način preizkušanja ima seveda za posledico veliko število potrebnih preizkušancev, katerih priprava običajno ni niti enostavna, niti poceni. Po drugi stran preizkušanje tega ogromno časa. Dejstvo pa je, da je bil - izhajajoč iz zasnove vpenjalne enote pri doslej znanih napravah - tak način preizkušanja pač edino možen in relevanten za pridobitev rezultatov preizkušanja kotalčnega utrujanja, ki ponazorijo stanje preizkušanca glede na trajanje oz. število ponovitev kotalčne obremenitve.With the devices known so far, it was possible to achieve only stage-by-stage observation of the events with several identical test subjects who were tested one after the other to different stages. Thus, the first subject was introduced, subjected to a rolling load for a certain period of time and thus a certain number of repetitions of the load, removed from the clamping device, and then observed, measured and the like. Thereafter, the experiment was repeated with another subject and subjected to loading, e.g. for an appropriately longer period of time, thus ensuring an even greater number of load repetitions. This type of testing, of course, results in a large number of test subjects, whose preparation is usually neither easy nor cheap. On the other hand, trying this huge time. The fact is that, based on the design of the clamping unit of the devices known so far, such a method of testing was only possible and relevant for obtaining the results of rolling fatigue tests, which illustrate the condition of the subject in terms of duration or duration. number of repetitions of rolling load.

Po izumu je naprava za preizkušanje odpornosti na kotalčno utrujanje gradiv sicer prav tako v osnovi izvedena z vpenjalno enoto, obremenilno enoto in pogonskim sklopom, s katerim je povezana in premakljiva omenjena obremenilna enota, ki je zasnovana s preizkuševalno kroglo, ki jo je možno kotaliti po preizkuševalni površini vsakokratnega preizkušanca, vpetega v vpenjalni enoti. Vendar pa je po izumu obremenilna enota opremljena še z omejevalno ploščo, s katero je na obremenilni enoti enoznačno in ponovljivo določljiva vsaj ena končna točka kotaleče se preizkuševalne krogle. Pri prednostni izvedbi je omenjena omejevalna plošča pritrjena na spodnji, proti preizkušancu obrnjeni strani obremenilne enote in izvedena na ta način, daje preizkuševalna krogla vsaj deloma obdana z omejevalno ploščo v svoji ekvatorialni oz. s preizkuševalno površino preizkušanca vzporedni ravnini. Nadalje je omejevalna plošča prednostno tako izvedena, da v ravnini, ki je vzporedna s preizkuševalno ravnino preizkušanca, omogoča premikanje preizkuševalne krogle med kotaljenjem v vzdolžni smeri, hkrati pa pri tem onemogoča njeno premikanje v prečni smeri v omenjeni ravnini.According to the invention, the device for testing the resistance to rolling fatigue of materials is also basically made with a clamping unit, a load unit and a drive assembly to which said load unit is connected and movable, which is designed with a ball which can be rolled over the test surface of each test piece clamped in the clamping unit. However, according to the invention, the load unit is further provided with a restraining plate, with which at least one end point of the rolling test ball is uniquely and reproducibly identifiable on the load unit. In a preferred embodiment, said restraining plate is attached to the lower face of the load unit facing the test subject and constructed in such a way that the test ball is at least partially surrounded by a restraining plate in its equatorial or. with the test surface of the test piece parallel to the plane. Further, the restraining plate is preferably designed so that in a plane parallel to the test plane of the test piece, it permits movement of the test ball while rolling in the longitudinal direction, while preventing its movement in the transverse direction in said plane.

Vpenjalna enota je opremljena z vpenjalno ploščo, na kateri je prednostno na voljo vsaj ena podolgovata skoznja luknja za pritrditev vpenjalne plošče na vsakokrat ustrezno podlago. Vpenjalna plošča je zasnovana z vpenjalnim gnezdom, kamor je namestljiv preizkušanec in ob katerem so v pripadajočih utorih ohlapno prilegajoče se in vzdolž vsakokrat pripadajočega utora premakljivo nameščeni naslonski nastavki, ki jih je možno v določenem položaju učvrstiti ter s tem onemogočiti njihovo nadaljnje nehoteno premikanje vzdolž vsakokrat pripadajočega utora. Pri prednostni izvedbi je v dnu vsakega od utorov vpenjalne plošče na voljo navojna luknja, vsak od v omenjenih utorih nameščenih naslonskih nastavkov pa je opremljen s podolgovato skoznjo luknjo, potekajočo v vzdolžni smeri vsakokrat pripadajočega utora. Pri tem je vsakokraten naslonski nastavek v vsakokrat ustreznem položaju oprtja na preizkušancu v vsakokrat pripadajočem utoru pritrdljiv oz. učvrstljiv na mestu s pomočjo vijaka, ki je skozi vsakokrat pripadajočo podolgovato skoznjo luknjo naslonskega nastavka segajoče privit v vsakokrat pripadajoči navojni luknji v dnu vsakokrat pripadajočega utora.The clamping unit is provided with a clamping plate, which preferably has at least one elongated through hole for securing the clamping plate to the respective base. The clamping plate is designed with a clamping socket, for which a test piece is mounted, and in which the slots, which are loosely fitted and movable along the respective grooves, are movable in the respective grooves, which can be fixed in a certain position to prevent their further unintentional extension. of the associated groove. In a preferred embodiment, a threaded hole is provided at the base of each of the grooves of the clamping plate, and each of the recessed mountings fitted in said grooves is provided with an elongated through hole extending in the longitudinal direction of the respective groove. In this case, the backrest in each corresponding position of the test piece in the respective groove is fixed in each respective groove. it is secured in place by means of a screw which is threaded through the correspondingly elongated through hole of the backrest to the threaded hole in the bottom of the respective groove.

Naprava po izumu bo v nadaljevanju podrobneje opisana na osnovi primera izvedbe, prikazanega na priloženi skici, pri čemer kažejo sl. 1 napravo za preizkušanje odpornosti na kotalčno utrujanje gradiv, v narisu;The apparatus of the invention will now be described in further detail based on the embodiment shown in the accompanying drawing, with FIGS. 1 device for testing rolling resistance of materials, in outline;

sl. 2 napravo v prerezu v ravnini II - II po sl. 1, in sl. 3 zgolj vpenjalno enoto naprave po izumu, in sicer v tlorisu.FIG. 2 is a cross-sectional view of the device in plane II - II according to FIG. 1, and FIG. 3 only the clamping unit of the device according to the invention, in plan.

Primer izvedbe naprave po izumu, ki je prikazan na sl. 1-3, je prirejen za izboljšan način preizkušanja na kotalčno utrujanje, pri katerem je zahvaljujoč izboljšani zasnovi celotne preizkuševalne naprave omogočeno linearno oscilatomo kotaljenje krogle 10 po površini 20 preizkušanca 2 sem ter tja.An example embodiment of the device according to the invention shown in FIG. 1-3, is adapted for improved rolling fatigue testing, which, thanks to the improved design of the entire test rig, enables a linear oscillation of the ball 10 to roll over the surface 20 of test specimen 2 here and there.

Naprava v osnovi sestoji iz obremenilne enote 1, na skici neprikazanega pogonskega sklopa in iz vpenjalne enote 3, v katero je namestljiv oz. je možno vpeti preizkušanec 2.The device basically consists of a load unit 1, a sketch of a drive train not shown, and a clamping unit 3 into which it can be installed or mounted. it is possible to mount test subject 2.

V splošnem obstaja možnost izbire najrazličnejših oblik in izvedb preizkušancev 2, vsekakor pa vsakokraten preizkušanec 2 obsega vsaj eno ravno preizkuševalno površino 20 za samo izvedbo preizkusa ustrezne dolžine.In general, there is a choice of the various shapes and designs of test pieces 2, but in any case, test pieces 2 each comprise at least one flat test surface 20 for performing the test of the proper length.

Obremenilna enota 1 je v danem primeru opremljena z navojnim drogom 11, preko katere je povezana z neprikazanim pogonskim sklopom, ki je v danem primeru najbolj smotrno lahko kar običajen, strokovnjakom dobro znan ročični mehanizem. Nadalje je obremenilna enota 1 na svoji spodnji, proti vsakokratnemu preizkušancu 2 oz. njegovi površini 20 obrnjeni strani opremljena s tečino 12, v katere žlebu 13, potekajočem v vzdolžni smeri glede na površino 20 preizkušanca 2, je oprta preizkuševalna krogla 10 ustreznega premera. V duhu pričujočega izuma je na omenjeni tečini 12 pritijena omejevalna plošča 14, in sicer v danem primeru s pomočjo ustreznih zatičev 17 in vijakov 16. Na ta način je v tem primeru preizkuševalna krogla 10 v svoji ekvatorialni ravnini, oz. v tisti diametralni ravnini, ki je vzporedna s površino 20 preizkušanca 2 deloma obdana z omejevalno ploščo 14, in sicer na tak način, daje omogočeno zgolj po dolžini omejeno premikanje oz. kotaljenje krogle 10 po površini 20 preizkušanca 2, in sicer v smeri vzdolž žleba 13, ne pa tudi v smeri prečno glede na žleb 13.The load unit 1 is optionally provided with a threaded rod 11 through which it is connected to a non-shown drive assembly, which in this case is most conveniently known to a conventional, well-known crank mechanism. Further, load unit 1 is at its lower end, against the respective test piece 2 or. its surface 20 facing side is provided with a fluid 12 into which a groove 13 extending longitudinally with respect to the surface 20 of the test piece 2 is supported by a test ball 10 of appropriate diameter. In the spirit of the present invention, a limiting plate 14 is attached to said fluid 12, optionally by means of suitable pins 17 and screws 16. Thus, in this case, the test ball 10 is in its equatorial plane, or. in the diametrical plane parallel to the surface 20 of the test specimen 2 partially enclosed by the restraining plate 14, in such a way that only a limited length of movement or movement is allowed. rolling the ball 10 over the surface 20 of the test piece 2, in a direction along the groove 13, but not in a transverse direction with respect to the groove 13.

Vpenjalna enota 3 obsega vpenjalno ploščo 30, opremljeno z vpenjalnim gnezdom 31, kot tudi z več - v danem primeru petimi - naslonskimi nastavki 32, od katerih je v danem primeru vsak nameščen v pripadajočem utoru 34. Vpenjalno ploščo 30 je možno pritrditi na ustrezno podlago s pomočjo običajnih vijakov, ki na skici sicer niso prikazani, v ta namen pa sta v danem primeru predvideni dve podolgovati luknji 33', 33.The clamping unit 3 comprises a clamping plate 30 provided with a clamping socket 31, as well as a plurality of, if necessary, five support brackets 32, each of which is optionally mounted in a corresponding groove 34. The clamping plate 30 may be attached to a suitable base. by means of conventional screws which are not otherwise shown in the sketch, for which purpose two elongated holes 33 ', 33 are provided for this case.

Ob vpenjalnem gnezdu 31 so na vpenjalni plošči 30 na voljo na kar najbolj ustrezen način razporejeni utori 34. Na dnu 34' vsakega od utorov 34 je na voljo navojna luknja 35. Razen tega je v vsakem utoru 34 ohlapno prilegajoče se in v vzdolž vsakokrat pripadajočega utora 34 premakljivo nameščen po en naslonski nastavek 32. Vsak od omenjenih naslonskih nastavkov 32 je opremljen s podolgovato, vzdolž vsakokrat pripadajočega utora 34 potekajočo skoznjo luknjo 36. Zahvaljujoč tovrstni zasnovi utorov 34 in naslonskih nastavkov 32 je vsakokraten naslonski nastavek 32 po premiku vzdolž utora 34 v določen položaj možno v tem položaju učvrstiti in zavarovati proti nadaljnjemu nehotenemu premikanju s pomočjo ustreznega vijaka 37, ki je skozi podolgovato luknjo 36 vsakokrat pripadajočega naslonskega nastavka 32 privit v navojno luknjo 35 v dnu 34' pripadajočega utora 34 vpenjalne plošče 30.Along the clamping slot 31, grooves 34 are provided in the most suitable manner in the clamping plate 30. A threaded hole 35 is provided at the bottom 34 'of each of the grooves 34. In addition, there is a loosely fitted fitting in each groove 34 and the corresponding grooves along each one. grooves 34 are movably mounted one backing nozzle 32. Each of said backrests 32 is provided with an elongate hole 32 extending along the respective grooves 34. Thanks to this design of grooves 34 and backrests 32, each backrest nozzle 32 is displaced along the groove 34 in a certain position it is possible to secure and secure in this position against further inadvertent movement by means of a suitable screw 37 which is screwed through the elongated hole 36 of the respective backrest 32 into the threaded hole 35 in the bottom 34 'of the corresponding groove 34 of the clamping plate 30.

Pri preizkušanju preizkušanec 2 vpnemo v vpenjalno 3 enoto na ta način, da ga namestimo v vpenjalno gnezdo 31 vpenjalne plošče 30, in ga obrnemo v tako smer, da preizkusna površina 20 v zadostni dolžini za izvedbo samega preizkusa dovoljuje kotaljenje krogle 10. Pri odvitih vijakih 37 je možno vsakega od naslonskih nastavkov 32 vzdolž pripadajočega utora pritisniti ob preizkušanec 2 in zatem priviti pripadajoč vijak 37. Na ta način je možno preizkušanec 2 za potrebe preizkusa zadovoljivo in korektno vpeti v vpenjalno enoto 3. Po drugi strani je možno v žlebu 13 tečine 12 oprto preizkusno kroglo 10 zahvaljujoč omejevalni plošči 14 namestiti v eno od obeh dosegljivih skrajnih točk v žlebu 13 tečine 12. V takem stanju je možno pričeti s preizkusom, torej pod določeno obremenitvijo kotaliti kroglo 10 po površini 20 preizkušanca 2 sem ter tja.In the test, test piece 2 is clamped into the clamping unit 3 in such a way that it is placed in the clamping slot 31 of the clamping plate 30 and rotated in such a way that the test surface 20 permits the ball 10 to roll in sufficient length to perform the test itself. 37 it is possible to press each of the restraints 32 along the corresponding groove next to the test piece 2 and then tighten the corresponding screw 37. In this way, the test piece 2 can be satisfactorily and correctly clamped into the clamping unit 3. For the purposes of the test, it is also possible in the groove 13 of the fluid 12, by means of the restraint plate 14, place the test ball 10 in one of the two reachable ends in the groove 13 of the fluid 12. In such a condition, it is possible to start the test, so that under a certain load the ball 10 can be rolled over the surface 20 of the test specimen 2 here and there.

Po določenem času oz. določenem številu ponovitev obremenitve oz. kotaljenja krogle 10 sem ter tja po površini 20 preizkušanca 2 je možno preizkus prekiniti. Obremenilno enoto 1 namestimo v položaj, ko se preizkusna krogla 10 nahaja v eni od obeh skrajnih točk omejevalne plošče 14. Po drugi strani je možno že s popustitvijo vijakov 37 zgolj dveh od petih naslonskih nastavkov 32 vpenjalne enote 3 doseči sprostitev preizkušanca 2. Če v danem primeru (sl. 3) odvijemo zgolj npr. levi in spodnji ali desni in spodnji vijak 37, preostali trije naslonski nastavki 32 pa ostanejo pritrjeni v obstoječem položaju, je možno preizkušanec 2 odstraniti iz vpenjalnega gnezda 31 vpenjalne plošče 30 in ga zatem - npr. po izvršenih meritvah ali opazovanju - ponovno namestiti v prejšnji položaj s prislonitvijo in pritrditvijo omenjenih dveh naslonskih nastavkov 32 ter na ta način vzpostaviti prejšnje stanje.After a certain time or. a certain number of load repetitions or the rolling of the ball 10 back and forth across the surface 20 of the test piece 2 can be interrupted. Place the load unit 1 in a position where the test ball 10 is located at one of the two extreme points of the restraint plate 14. On the other hand, it is already possible to loosen the test piece 2 by loosening the screws 37 of only two of the five mounting units 32 of the clamping unit 3. In the given example (Fig. 3) we unscrew only e.g. left and bottom or right and bottom screw 37, and the remaining three backrests 32 remain fixed in the existing position, it is possible to remove test piece 2 from the clamping slot 31 of the clamping plate 30 and then - e.g. after measurements have been made or observation - reinstalled to the previous position by tapping and securing the two backrests 32 to restore the previous state.

Po prekinitvi preizkusa je torej možno z omenjenima ukrepoma v smislu pozicioniranja preizkuševalne krogle 10 in samega preizkušanca 2 brez težav zagotoviti odstranitev preizkušanca 2 iz vpenjalne enote ter zatem - po v splošnem kjerkoli izvršenih opazovanjih in meritvah - brez nadaljnjega in na vsekakor ponovljiv način natančno vzpostaviti prejšnje stanje. S tem so omogočene v splošnem lahko tudi večkratne prekinitve preizkusov z izvajanjem vmesnih opazovanj in meritev, zatem pa je možno brez težav nadaljevati preizkus s ponovno vstavitvijo preizkušanca 2 nazaj v vpenjalno gnezdo 31 med ustrezno nameščene naslonske nastavke 32 in utrditvijo v takem položaju zgolj s privitjem vijakov 37.Upon termination of the test, it is therefore possible to easily remove the test specimen 2 from the clamping unit by means of the aforementioned measures in terms of positioning the test ball 10 and the test piece itself 2, and then, after generally observing and measuring the measurements carried out, without previous and in any event reproducible state. This generally enables multiple interruptions of the tests by performing intermediate observations and measurements, and it is then easy to continue the test by re-inserting the test piece 2 back into the clamping slot 31 between the properly fitted backrests 32 and consolidating in such a position only by screwing screws 37.

Claims

PATENT APPLICATIONS

A device for testing rolling resistance of materials with possible intermittent interruptions, comprising a suitable drive assembly connected to and a movable load unit (1) equipped with a test ball (10) which can be rolled over the test surface (20 ) of each test piece (2) clamped in the clamping unit (3), characterized in that the load unit (1) is provided with a restraining plate (14), which makes at least one end of the load unit (1) uniquely and repeatable. the point of rolling of the test ball (10), and the clamping unit (3) is provided with a clamping socket (31) to which the test specimen (2) is mounted, and in which the slots (34) fit loosely and along the respective groove (34) ) movably mounted backrests (32) that can be fixed in a certain position, thereby preventing them from being moved inadvertently along the respective attachment grooves (34).

Apparatus according to claim 1, characterized in that the restraining plate (14) is attached to the lower face of the loading unit (1) facing the test piece (2) and so arranged that the test ball (10) is at least partially surrounded by the limiting plate (14) in its equatorial, with the test surface (20) of the test specimen (2) in a parallel plane.

Apparatus according to claim 2, characterized in that the restraining plate (14) is so arranged that, in a plane parallel to the test plane (20) of the test piece (2), it is possible to move the test ball (10) while rolling in the longitudinal direction of the test specimen (2), while preventing its movement in the transverse direction in said plane.

Device according to any one of the preceding claims, characterized in that a threaded hole (35) is provided in the bottom (34 ') of each of the grooves (34) of the clamping plate (30) and that each of said grooves (34) fitted backrests (32) provided with an elongated through hole (36) extending in the longitudinal direction of the respective groove (34).

Apparatus according to claim 4, characterized in that the respective backrest (32) is, in each appropriate position, supported by the test piece (2) in the corresponding groove (34), respectively. secured in place by means of a screw (37) extending through the respective elongated through hole (36) of the backrest (32) into the respective threaded hole (35) in the bottom (34 ') of the respective groove (34).

Apparatus according to any one of the preceding claims, characterized in that at least one elongated through hole (33 ', 33) is provided on the clamping plate (3) for attaching the clamping plate (3) to the respective base.