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Distribution of grease in rolling bearing
Hynek, Jakub ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The work deals with the issue of grease distribution in a rolling bearing. Grease lubricated ball bearing in this way often experience the problem of starvation, when the contact area is not sufficiently supplied with lubricant, which leads to bearing failure. In general, this is a very complex and comprehensive topic. Specifically, the description of the effect of selected parameters on the distribution of grease in the rolling bearing was solved. The evaluation took place on the contact surfaces of the inner and outer ring and bearing balls. The average film thickness in selected areas at the point of contact and in front of it were evaluated. The method for observation was fluorescence microscopy. The effects of the percentage filling of the bearing with grease, the speed, the material and the design of the cage on the distribution and distribution of the grease on the bearing surfaces are described in the thesis. The result is information about the distribution of the grease on the raceways and balls of the bearing and their immediate surroundings. It was shown that the new experimental approach used makes it possible to evaluate the amount of grease available for bearing lubrication in a real configuration.
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Study of starvation in a grease-lubricated elastohydrodynamic contact
Kuňák, Jiří ; Hartl, Martin (referee) ; Svoboda, Petr (advisor)
This diploma thesis is an experimental study of grease lubrication in a starved elastohydrodynamic lubricated (EHL) contact. Lubricating film thickness is measured with tribological experimental device ball-on-disc using optical interferometry and high speed camera. The experiment is aimed at a comparison of results acquired by ball-on-disc device and full scale axial bearing. In addition, this paper also investigates the influence of number of the rolling elements (overrolling time) on the resulting film thickness.
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Development of a testing system for evaluation of rolling bearings with variable lubrication parameters
Škoviera, Jozef ; Čermák, Jan (referee) ; Omasta, Milan (advisor)
The presented diploma thesis deals with the design of a test system for rolling bearings, which allows the change of the lubrication parameters (e.g. changing of the relubrica-tion interval). In the document, the reader first learns about the meaning of lubrication of rolling bearings, the possibilities of lubricant supply to the bearing (specifically for the supply of grease) and the possibilities of dosing control. Subsequently in the document is described the present state of experimental stations for testing rolling bearings, which is available at the Institute of Machine and Industrial Design. The end of the part about current state of knowledge is also mentioned the possibility of speeding up fatigue tests. In the next part, the author describes his own solution. The result is the design of an experimental station (for option to relubricate with grease), the creation of a lubrication control platform and the creation of a basic program. Part of the work is also verification experiments and drawing documentation.
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Study of Correlation between Grease Film Formations and Mechanical Losses on Various Surfaces
Sakai, Kazumi ; Glovnea, Romeo (referee) ; Gonçalves, David (referee) ; Křupka, Ivan (advisor)
Tato disertační práce se zaměřuje na studium závislosti mezi reakčním momentem ložiska mazaného plastickým mazivem s lithným mýdlem a vlastnostmi maziva, jako například tloušťka vytvářeného mazacího filmu, jeho reologie, struktura zpevňovadla, trakční vlastnosti či vliv topografie povrchu. Typ maziva poskytujícího nižší odpor závisí na podmínkách provozu ložiska, zejména rychlosti. Chování mazacího filmu za nízkých rychlostí má vliv na reakční moment ložiska v nízkých rychlostech. Mez toku a trakční chování koreluje s momentem ložiska za vysokých rychlostí. Schopnost zpevňovadla vstupovat do kontaktu má vliv na tloušťku filmu, vzhled kavitační oblasti na výstupu kontaktu a chování hladovění. Důvod vstupu zpevňovadla do kontaktu je jeho chemická struktura. Vysoká polárnost hydroxylových sloučenin zpevňovadla podporuje jeho vtažení kontaktními povrchy. Mazivo s nejvyšší polaritou prokázalo na površích obsahujících denty nejčastější vstup do prostoru dentů. Na základě předchozích pozorování je navržen popis principu mechanismu mazání.
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Influence of the grease aging to its behavior in the vicinity of the elastohydrodynamic contact
Navrátil, Marek ; Dzimko, Marián (referee) ; Košťál, David (advisor)
This thesis aims to describe the differences in grease behaviour caused by degradation. Observation of EHL contact and its surroundings is done using optical fluorescence, which allows to measure lubricant thickness even if it is discontinuous and air is present. New grease is observed, along with samples aged in bearings. One sample was worked for 1000 hours, which was the planned duration of the experiment. Two other samples were stopped prematurely after approx. 900 hours. Several possible age-related factors were examined and strong link between contamination and grease behaviour was found. In observed cases, contamination was identified to be the leading cause of lubricant shortage near EHL contact, which is one of possible bearing failure causes. The results expand existing knowledge about grease lubrication topic, but much further research is needed.
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Review of grease types
Mauer, Jindřich ; Ficza, Ildikó (referee) ; Košťál, David (advisor)
This bachelor thesis provides a basic distribution of greases according various aspects, which are used for lubrication the various components. The first part of bachelor thesis deals with the composition of greases. The following section describes the manufacture of greases. Another section includes the distribution of greases in terms of their composition. The following section is about distribution of greases in terms of practical use. The last part of the bachelor thesis deals with transmission electron microscopy, by this method is possible to examine the structure of greases.
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Design of adaptive wiper of liquids
Novotný, Antonín ; Nečas, David (referee) ; Košťál, David (advisor)
This thesis deals with the structural design of the adaptive fluid wiper, which is the complement of laboratory equipment. Laboratory equipment is used to study the thickness of the lubricating layer and the frictional force at contact. The purpose of the adaptive wiper is to remove the maximum amount of liquid from a moving planar disc or to make a uniform film in a rolling path around the periphery of the disc. Among the most controllable features, there are the wiper geometry, the evenly pressing and the follow the disc throwing. The thesis includes the design report, drawings and 3D model.
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Experimental observation of grease migration in a rolling bearing simulator
Palán, Miroslav ; Okál, Michal (referee) ; Košťál, David (advisor)
This thesis is using fluorescence microscopy to separately observe components of grease lubricate in simulator of ball rolling bearing. Simulator is in the configuration ball-on-disk when the disk was replaced by the outside ring made by tempered glass. This ring allows light passing to normally unseeable places of steel bearing. By the separate study of greases particles, coloured with special fluorescent dye, was found that method of fluorescence microscopy can be used to gain information about grease lubricated process in bearing.
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Grease lubrication in rolling element bearings
Kroupa, Jiří ; Čermák, Jan (referee) ; Frýza, Josef (advisor)
This diploma thesis deals with an analysis of lubrication film in contacts of simulated thrust ball bearing lubricated by greases and comparison of the film thickness between this apparatus and ball-on-disc. According to the literature, ball-on-disc is the most used apparatus for studies of EHL. But these devices neglect some important factors acting in real bearing such as presence of cage, number of rolling elements, their spin or a type of contact geometry. Therefore it is necessary to investigate comparability of these approaches. For this purpose, measurements on unique apparatus of simulated thrust ball bearing are performed. The effect of each factor is evaluated employing Factorial design method. Significant differences are discovered between results, primarily in tendency of contacts to starvation. According to these results, it is necessary to focus the research in the field of bearing lubrication on conditions closer to real bearings.
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Experimental Study of Wheel Flange Lubrication
Frýza, Josef ; Dzimko, Marián (referee) ; Omasta, Milan (advisor)
This diploma thesis deals with the experimental study of the influence of operating conditions on the tribological aspects of the wheel flange and rail gauge contact. The wheel flange contact occurs when the vehicle moves on a curve track and it leads to severe up to catastrophic wear regime. For effective reduction of wear is important to apply a suitable amount of lubricant at appropriate intervals into the contact. The issue in this work comprehensively studies using of three laboratory apparatus and six methods that are theoretically and experimentally compared. Assessed are friction, wear, distribution and film thickness of lubricants for different contact conditions. The resulted amount of lubricant and interval of its application eliminates development of seizure at low consumption of lubricant. The understanding of mechanisms that occur in the wheel-rail contact not only helps to reduce operating costs and improved to energy efficiency of movement of vehicle on a track, but it is the basis for safe, reliable and ecological operation of rail transport.
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