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Development of Film Thickness in Elastohydrodynamically Lubricated Compliant Contacts
Křupka, Jiří ; Fillot, Nicolas (referee) ; Glovnea, Romeo (referee) ; Křupka, Ivan (advisor)
Mazání polymerních strojních součástí, jako jsou polymerní ozubená kola, je v současné době předmětem zájmu mnoha strojírenských aplikací z hlediska simulace mazacích procesů a optimalizace tribologických podmínek pro zvýšení výkonnosti těchto součástí. Předkládaná disertační práce se zabývá experimentální studií vývoje tloušťky kapalinového filmu v elastohydrodynamicky mazaných poddajných kontaktech. Hlavním cílem práce je objasnit formování tloušťky filmu v poddajných kontaktech v přechodové oblasti (TR) mezi isoviscous-elastic (I-E) a piezoviscous-elastic (P-E) režimem elastohydrodynamického mazání (EHL). Za tímto účelem byly provedeny laboratorní experimenty na rotačním optickém tribometru v konfiguraci kulička na disku, ve kterých byla implementována metoda optické chromatické interferometrie. Experimentálně byl analyzován vliv jak reologické odezvy maziva, tak konstitutivní viskoelastické odezvy polymeru na tvorbu tloušťky kapalinového filmu. Na základě výsledků byla dokumentována nízká platnost predikčních modelů tloušťky filmu I-E a P-E v oblasti TR. Výsledky prezentované v této práci rozšiřují poznatky o tvorbě mazacího filmu v poddajných kontaktech pracujících v režimu EHL a mohou tak být zohledněny při návrhu polymerních strojních součástí nebo při řízení mazacích procesů.
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Lubrication of plastic gears
Hartl, Petr ; Čermák, Jan (referee) ; Křupka, Jiří (advisor)
The work deals with the process of lubrication of gears from a combination of materials that have significantly different material properties. The experimental measurement is performed on a tribometer in simulated gear contact with a ball-disk configuration. The Chromatic Optical Interferometry method is used to measure the formation of a lubricating film in contact. The purpose of this work is to clarify the process of film thickness formation and compare experimental measurements with predictions, which are valid in Soft EHL regime.
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Design of a steam engine
Duchoň, Matěj ; Křupka, Jiří (referee) ; Košťál, David (advisor)
This bachelor theses deals with a construction of a model of a single-cylinder static steam engine driven by an external heat source. In this construction, the overall size and weight were limiting. As a part of this theses, the research on existing constructions was carried out. Based on these findings, three conceptual studies were elaborated. As a result, a design solution of a steam engine in a configuration with a flat slide valve and an open crosshead guidance was designed. The model serves as a teaching aid for understanding the principles of the earlier piston machines and for explaining the basic machine mechanisms and thermodynamic process.
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Pallet truck
Paulíček, Jiří ; Křupka, Jiří (referee) ; Brandejs, Jan (advisor)
The aim of this bachelor thesis is to design a pallet truck, equipped by mechanism which allows the truck to be loaded into van. Truck is designed for manual-hydraulic drive of forks and for load of 1000kg. The basic types of pallet trucks are described in the research part. There is also described Innolift, which is only one with the self-loading mechanism. The main construction nodes are solved in the design part including strength calculations
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Construction of gears with plastic teeth
Selzer, Tomáš ; Vrbka, Martin (referee) ; Křupka, Jiří (advisor)
The thesis discusses the matter of construction of gear trains using plastic parts in both lubricated and non-lubricated environment, trying to give an overview of an up-to-date information in the process. Nowadays, thanks to several years of development, polymer-based gear systems can be used in many cases as a replacement for metal-based ones. The undeniable advantage of such replacement is mostly the lower production cost and its lower weight, which, together with favorable friction properties of polymer materials, makes a number of technological applications much more effective. The first part is dedicated to listing and defining the typical characteristics of polymer materials, which are essential in the process of designing the gear. The next part focuses on evaluation of the available types of solutions for plastic gear trains construction. The last topic is centered around possible defects and the wear as well as the operation conditions and a real-life application of such plastic gear system. The most notable findings are summed up and commented on in the form a discussion. Thanks to the chosen topic, the bachelor’s thesis adds to a closer understanding of the construction and operation of the plastic gear systems.
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Construction materials for plastic gears
Vystrčil, Tomáš ; Dočkal, Kryštof (referee) ; Křupka, Jiří (advisor)
This thesis presents an overview of current knowledge of plastic gearing. It is focused on used materials and methods of processing. List of used plastic materials and their properties is presented. Thesis includes a tables of properties of these materials, which allows comparison. Benefits, deficiencies and typical applications of plastic gearing are discussed. Common technologies usable for production of gearing are mentioned. Their advantages, disadvantages and currency is discussed. Thesis gives a summary of this knowledge.
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Modification of the test rig for the testing the bearings for the space applications
Okál, Michal ; Křupka, Jiří (referee) ; Košťál, David (advisor)
This bachelor thesis deals with the design of a device, which allows exploration of rolling bearings properties in space conditions. The adjustment is necessary for testing of a new rolling bearing with different dimensions. Preload of the bearing must be centered and adapted for rapid heat exchange with the surroundings. The effort is made to use maximum number of existing components and torsion stiffness of the device. The thesis outputs are the accompanying report and the technical documentation allowing the production of new components.
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Magnetic separator
Křupka, Jiří ; Jonák, Martin (referee) ; Malášek, Jiří (advisor)
The aim of this bachelor thesis is to design the structural conception of magnetic separator designated to separate small-sized industrial waste. This report provides an overview of facilities of worldwide manufacturers that are used for magnetic separation of steel scrap. Furthermore, it offers an assessment of variants for technical solutions to structural nodes of magnetic separator; this is followed by a selection of specific solution. According to the input parameters, all the parameters necessary for correct machine design are computed. These computations also include the justification of selected table values, placement, surface roughness, geometric tolerances, materials and heat treatment of the individual parts and assemblies. Attachments to this technical report are documentation drawings of selected parts and assemblies.
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Gear design with tolerance analysis
Křivohlavý, Petr ; Křupka, Jiří (referee) ; Svoboda, Petr (advisor)
The thesis is concerned with tolerances of machine elements. The thesis explains dimensional and geometrical tolerance, surface texture and their interdependence. On the basis of the stated facts a simple technique is established to be followed when setting tolerance of machine elements. The procedure is further applied on the transmission that was selected from the three models on hand. The technique is focused mostly on shaft and gear tolerance. The thesis should provide the reader with understanding of how to tolerate selected machine elements.
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Development of ventilating turbines
Křupka, Jiří ; Malach, František (referee) ; Malášek, Jiří (advisor)
This Master thesis solves a construction development of alternative modular mechanical systems for ventilation turbines. A research part of the thesis deals with the issues of transported medium (air) and ventilation, as well as functions, designs of ventilation turbines, and finally it provides an overview of ventilation turbines produced by manufacturers worldwide; these are used for ventilation of residential, commercial, industrial or agricultural structures using the natural or hybrid ventilation. A construction - design part is focused on creating 3D models of selected alternative modular adjustable ventilation turbines according to the data provided by the thesis supervisor and then on establishing a system for calculating the shapes of blades relative to the airflow for additional axial fan of ventilation turbines. For this purpose, a customized software application VENTILATOR (GUI) was developed to allow a flexible change of input calculation parameters and thus a fast modification of the curve shape in the 3D model of the axial fan blade.
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