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Optimizing of die geometry for wet drawing of a steel wire with process fluid
Bršťák, Ondřej ; Zmrzlý, Martin (referee) ; Píška, Miroslav (advisor)
The subject of this diploma thesis was both the analysis of the wire drawing process and the design of a new drawing die. All tests were performed at real production line. The primary aim of the analysis was the change in the current lubricating medium. Based on the performed analysis the test was developed to determine the exact values of the friction coefficient of the new lubricant. In the following part of the thesis the wire manufacturing process was described with a focus on the performance of the drawing die. For that matter material tests were performed and a material model was developed and then used for further calculations. Based on the results the geometry of the drawing die was changed and hence the drawing process was optimized with the focus on both increasing the lifetime of the drawing die and maintaining the complexity of the production. First drafts of new drawing dies were created and cost savings were calculated. In the last section the next modifications were proposed to increase the lifetime of the drawing dies.
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Numerical simulation of oil flow in the gearbox
Činčár, Vojtěch ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
Component design, subsequent functional verification and possible optimization are an integral part of any production process. Based on increasing customer requirements, the aim is to achieve the smallest possible dimensions and the lowest possible price, while maintaining safety. Incorporating both aspects can be achieved using advanced computational approaches, while this work focuses on the area of flow simulation. Specifically, it deals with the analysis of oil flow in a railway vehicle gearbox using computational fluid dynamics or CFD. The flow simulations were performed using ParticleWorks software, which works with the semi-implicit moving particle method MPS, whose suitability was verified by short analysis works. By monitoring the flow in the workspace, the geometry of the gearbox housing was first verified. However, the critical areas are the bearings whose lubrication quality was analysed using a series of computational models that included the service conditions that may occur. In addition to summarizing the overall evaluation, the paper concludes by outlining a possible suggestion for the potential improvement of bearing distribution and lubrication quality.
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Design of device for material antiseizure testing
Burk, Filip ; Kvarda, Daniel (referee) ; Šperka, Petr (advisor)
Friction between materials can be partially eliminated by lubrication between surfaces. In order to select the correct lubricating oil, it is necessary to have the necessary test means to make an evaluation. One of these is a four-ball tester, which is lacking at the BUT Institute of Design. The aim of the bachelor thesis is the design of a modification of the existing tribometer R-MAT 3 for a four-ball configuration. The review part includes a description of the preparation, measurement and evaluation of the four-ball tester and an evaluation of conventional testers. The design of the ball mounting, drive and torque transfer to the tribometer spindle was carried out. Measurement and recording of friction torque, contact force and temperature during the test was also proposed. The result is a configuration ready for implementation. The review section includes a description of the preparation, measurement and evaluation of the four-ball test and an evaluation of conventional testers.
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An investigation of friction and lubrication of coated hip joint replacement
Balcárek, Ondřej ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
The thesis focused on studying the effects of a new hydrogel coating and material combinations on the coefficient of friction and formation of lubricating film in the conformal contact of hip joint replacement. Experiments were conducted using a ball-on-cup configuration with a hip pendulum simulator. The formation of the lubricating film was observed using fluorescence microscopy. The results showed that the application of the coating did not have a clear impact on the coefficient of friction. However, for pairs with a coated cup, there was a reduction in CoF by approximately 20%. Generally, lower friction was observed when using a ceramic joint head. Surprisingly, even more interesting results were obtained in the lubrication analysis, where the use of metal heads led to a reduction in the thickness of the lubricating layer. Ceramic pairs exhibited very stable behavior. In addition to friction and lubrication, the topography of the implants was further evaluated, and their wettability was analysed. Although the polymer coating was expected to be highly hydrophilic, the surface properties were only slightly influenced, which partly explains why there was no significant improvement in the tribological behavior of the replacement. As the coating applied is already patented and its effectiveness in reducing wear has been clearly demonstrated, it is appropriate to investigate this issue further, with more attention being paid to long-term experiments. Based on the obtained data, it appears that the short-term benefits of the coating are practically negligible. However, it is important to highlight that, except for minor exceptions, the application of the coating did not lead to a deterioration of properties, which is a significant outcome of this work.
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Numerical simulation of oil flow in bearing housing
Zogata, Filip ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis is concerned with the development of a computational model of the bearing node, since in the development of a synchronous generator, great emphasis is placed on the proper design of the bearing node, as this complex component has a direct effect on the overall efficiency of the generator. A large number of engineering experiments need to be used to test on the physical model, but it is also necessary to test using the numerical model, as the production of the prototype itself for testing is very costly, and therefore it is advisable to verify the prototype itself before production by a series of numerical simulations. Another important feature is the possibility to investigate even unfavourable or even extreme conditions, which are already very difficult, sometimes impossible, to test physically in the laboratory, and these numerical simulations can be divided according to several parameters, but in the field of bearing nodes we mainly encounter structural, dynamic, temperature or flow problems. This thesis in particular is focused on establishing a basic overview of computational fluid dynamics in the oil flow domain, while this knowledge is used in practice, as another objective is to develop a numerical model of lubrication of the aforementioned bearing node. However, this is a very complex problem, and therefore a study is first carried out to investigate the key components, and only by gradually adding different elements is the numerical model created in the Particleworks software environment, while a sensitivity study is carried out focusing on particle size. Subsequently, the individual partial results are summarized in the conclusion of this paper.
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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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The Effect of Synovial Fluid Constituents on Friction and Lubrication of Articular Cartilage
Čípek, Pavel ; Dr. Prashant K. Sharma (referee) ; Muňoz, Anna Neus Igual (referee) ; Vrbka, Martin (advisor)
Práce se zabývá problematikou biotribologie modelu synoviálního kloubu. Cílem práce je popsat vliv složek synoviální kapaliny na formování mazacího filmu v modelu synoviálního kloubu. Práce je zaměřena na experimentální analýzu součinitele smykového tření a jeho propojení s pozorováním adsorbovaného mazacího filmu v kontaktu pomocí fluorescenční mikroskopie. Součástí práce je návrh tribometru, který umožňuje vizualizaci v průběhu experimentů. Tribometr je vyroben, kalibrován a verifikován pomocí komerčního tribometru. Dále je součástí práce návrh metodiky experimentů včetně návrhu postupu pro zpracování a hodnocení výsledků. Pro zpracování záznamu z vizualizace kontaktu byl navržen speciální software, který pracuje na principu segmentace obrazu. Poslední část práce je zaměřena na aplikaci vyvinuté metodologie spolu s nově navrženým tribometrem, což umožňuje posoudit roli složek modelové kapaliny u formování mazacího filmu v modelu synoviálního kloubu. Experimentální část je založena na měření tření za současné vizualizace kontaktu. Tato práce prezentuje originální výsledky rozšiřující oblast biotribologie synoviálního kloubu, které mohou pomoci dalšímu rozvoji účinné léčby pacientů s nemocnými klouby.
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Lubricant Gap Shape Optimization of the Hydrodynamic Thrust Bearing
Ochulo, Ikechi ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The objective of this Master's thesis is to find, using genetic algorithm (GA), an optimal profile for lubricating gap of a thrust bearing of a turbocharger. Compared to the analytical profile, the optimal profile is expected to have minimized friction for an equivalent load capacity. Friction minimization is one way to increase the efficiency of the thrust bearing; it reduces the friction losses in the bearing. An initial problem was given: a thrust bearing with Load capacity 1000 N, inner and outer radii of 30mm and 60mm respectively, rotor speed of 45000 rpm and angle of running surface of $0.5^0$. Lubricant properties were also provided for the initial problem: oil density of $ 840 kg/m^3$, dynamic viscosity $(\eta)$ of 0.01 Pa.s With this data, the numerical solution of the Reynolds equation was computed using MATLAB. To obtain more information, the minimum lubricating gap thickness was also computed using MATLAB. With this information, the shape of the analytical profile, and its characteristics were found. The analytical profile was then used a guide to create a general profile. The general profile thus obtained is then optimized using GA. The characteristics of the generated profile is then computed and compared to that of the analytical profile.
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