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Study of the effects of ellipticity parameter on lubrication film shape
Pavlík, František ; Dzimko, Marián (referee) ; Křupka, Ivan (advisor)
Diploma thesis deals with elastohydrodynamic lubrication of point contacts, which surfaces are influenced by topography and velocity vector of one rubbing surface is misaligned. Author summarizes knowledge of previously published research articles, which fundamentally enrich current state of knowledge. Diploma thesis contains experimental measurement results of the film thickness and the way of lubrication film formation in elliptical contact for different ellipticity parameters, kinds of rubbing surfaces and angles of the velocity vector. New findings have helped to better understand the behaviour of highly loaded lubricated contacts taking place in machine components and completed the current state of knowledge with results that can be used in next thorough study of this issue.
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Study of quality cutting edge of aluminum and copper alloys for fusion cutting in depending on the process parameters during laser cutting using a fiber YbYAG laser
Pilarčík, Edmund ; Kaván, Martin (referee) ; Mrňa, Libor (advisor)
The diploma thesis discusses laser cutting of non-ferrous metals using fiber YbYag laser and evaluation of the roughness of cutting edge samples. To manufacture samples of aluminium Al 99,5, deoxidized copper Cu – DHP and brass CuZn37 were used combinations of process parameters according to Taguchi statistical method. Samples were subsequently evaluated, according to the ČSN EN ISO 9013 standard and sorted into roughness cathegories, and by technical and economical evaluation, the most economical process parameter combinations were found. Experimantal part is preceded by description of general methods of cutting, description of laser types, process parameters and their influence on the occurrence of the cutting edge defects and description of roughness measurement and standard ČSN EN ISO 9013.
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STUDY OF ENERGY ABSORPTION IN MICRO – STRUT LATTICE STRUCTURE PRODUCED BY SELECTIVE LASER MELTING
Vrána, Radek ; Schleifenbaum, Johannes (referee) ; Skalon, Mateusz (referee) ; Paloušek, David (advisor)
Předložená dizertační práce je součástí většího výzkumného projektu, který si klade za cíl využití mikro prutové konstrukce vyrobené technologií SLM jako absorbér rázové energie s přesně navrženými vlastnostmi. Hlavním cílem práce je vývoj numerického modelu deformačního chování mikro-prutové konstrukce vyrobeného technologií Selective Laser Melting (SLM) z materiálu AlSi10Mg. Aby bylo možné dosáhnout hlavního cíle dizertační práce, bylo nutné analyzovat vliv procesních parametrů technologie SLM na tvorbu vnitřních materiálových vad a drsnost povrchu při výrobě mikro-prutové konstrukce. Tyto imperfekce degradují její mechanické vlastnosti a jejich odstranění zlepší možnosti a přesnost numerické predikce. Výsledky ukazují významný vliv dvou hlavních parametrů – skenovací rychlosti laseru a výkonu laseru. Na základě těchto poznatků byly dále definovány parametry vstupní energie Ein a lineární energie Elin, které zahrnují oba zmíněné parametry a byly definovány jejich limitní hodnoty pro minimalizaci vzniklých imperfekcí. Deformační chování vyrobené mikro-prutové konstrukce bylo analyzováno na navrženém pádové zařízení, které umožňuje testování s dopadovou energií až 120 J. Deformační chování je vyhodnocováno s využitím obrazové analýzy záznamu vysoko rychlostní kamery a silového průběhu z tenzometru. Výsledky analýzy byly využity pro validaci numerického modelu v programu ANSYS Explicit, do kterého byly implementovány poznatky o reálném tvaru vyrobeného mikro-prutového materiálu ve formě eliptického modelu geometrie a informace o reálných mechanických vlastnostech ve formě vyvinutého materiálového modelu. Výsledné porovnání výsledků experimentu s predikcí numerického modelu ukazují dobrou shodu v místě maximálního zatížení Fmax (odchylka 5 %) i průběhu celé deformace vzorku. Tyto poznatky budou v budoucnu využity při návrhu absorbéru energie s definovanými mechanickými vlastnostmi.
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Measurement management system
Aichler, Jaroslav ; Doňarová, Jana (referee) ; Koška, Petr (advisor)
The subject of diploma thesis is analysis of the European Standard EN ISO 10012, which has a status of a Czech Standard (ČSN EN ISO 10012). It’s focused on roughness measurement. The thesis was written in cooperation with a private company called PLASMAMETAL Ltd. situated in Brno. The company offers coating applications for a variety of materials. Important part of the thesis is a measurement management system improvement manual for PLASMAMETAL Ltd. It’s also dealt with the economical aspect of an investement into a new measurement equipment.
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In-situ Study of Surface Topography Changes in Elastohydrodynamic Contact
Šperka, Petr ; Dzimko, Marián (referee) ; Návrat, Tomáš (referee) ; Dobeš, Petr (referee) ; Hartl, Martin (advisor)
This dissertation thesis deals with elastohydrodynamic lubrication (EHL) of surfaces with real roughness. Systematic study of surface harmonic components behaviour, during their passage of the EHL contact, by other authors led to retrieval of a uniform principle according which individual harmonic components deform inside the contact. Although the amplitude attenuation model can provide rapid tool for more accurate surface assessment in design process it has not been validated on real surfaces till now. The thesis represents pioneering work on quantitative analysis of real surfaces EHD measurements. It contains original and new results with real and model roughness features that in many cases confirm theoretical expectations. Deeper understanding of surface roughness behaviour inside EHL contact, which is typical for machine parts like bearings, gears, cams etc., can help to improve design process of the components and ultimately enable machines and equipment to work with lower energy requirements and higher durability.
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Roller-burnishing technology as finishing oparation.
Sekerka, Vít ; Sedlák, Josef (referee) ; Zemčík, Oskar (advisor)
This bachelor thesis deals with chipless finishing operation of roller-burnishing. It explains and describes basic ideas concerning finishing and hardening of machine components by means of roller-burnishing, parting of tools, application in manufacturing and techno-economic usage. Own project, which deals with rollerburnishing of inside conic surface, is part of the thesis too.
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Measurement of cutting edge roughness in the process of laser metal cutting using the Yb-YAG laser
Maňas, Petr ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The project elaborated in frame of bachelor´s degree program B-STG (“Mechanical Engineering Technology”, 2303R002), evaluates the roughness of samples of cutting edge laser cutting. Cutting performed the fiber Yb:YAG laser. The samples consisted of structural steel J235JR and DC01, stainless steel X5CrNi18-10 and aluminium alloys AIMg3. They were evaluated according to the ČSN EN ISO 9013 standard. The classification of samples into classes according to the standards of accuracy. The theoretical part is consists of a description of the methods of cutting, a basic principle of the laser and its types. It includes cutting parameters and their influence on the quality of subsequent defects. It is described roughness measurement and standard ČSN EN ISO 9013.
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Functional surfaces and surface texture
Novák, Jiří ; Brandejs, Jan (referee) ; Svoboda, Pavel (advisor)
The aim of this bachelor publication was an elaboration of professional recherche about geometric product specification (GPS). My publication contains the comparison of the foregone and current norms, which include parameters surface texture and notation surface texture, relation of surface texture and surface function, incoming development trends and needful supplements.
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Data selection and optimisation of cutting conditions for progressive production technologies of drilling with a step drill
Barák, Vít ; Fiala, Zdeněk (referee) ; Píška, Miroslav (advisor)
The thesis contains theoretical analysis of drilling by twist drill focused on the step drill. The review includes description of the drill geometry, calculation of the basic parameters of drilling, including forces and process optimization. Following is manufacturing process and analysis of the monolithic step drill designed for the required hole parameters. The optimal cutting conditions are necessary to find for the correct function of the tool. The load values of the tool are accurately assessed using a piezoelectric dynamometer, thereby obtaining the overall progress of individual loads. The roughness of the workpiece is evaluated by the optical measuring device.
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