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Determining the possibilities of increasing binding potencial of fly ash for the usage in cement composites
Jančaříková, Denisa ; Ďurica,, Tibor (referee) ; Klečka,, Tomáš (referee) ; Kulísek, Karel (referee) ; Hela, Rudolf (advisor)
The deliberate use of fly ash in the production of concrete has been used for decades, but recent trends tend to maximise its utility properties. These are different types of activations from chemical through thermal to mechanical. An alkaline agent is added to chemical activation which, by etching the glass structure of the ash grain, promotes its reactivity. Mechanical activation is mainly focused on granulometry and particle size distribution curve. In this thesis three mechanical activation methods are compared: separation the ash into fractions by grain size, mixing these fractions to achieve the ideal particle size distribution curve and grinding. Four types of ash were collected from the Tušimice power plant – ash from individual electrostatic separators (I, II and III) and SESYP ash which represents the total volume of production. Ash from individual separators differ not only in the particle size but also in the chemical composition and reactivity. Better properties generally have smaller ash particles. This is used by mechanical activation by sorting. When mixing the individual ash fractions, the aim is to achieve an optimal grading curve of either the ash itself or the fine particle set in the concrete. In this work, ash is only used to calculate the mixing ratio and the grading curve according to Funk was selected as optimal. The last compared option of activation was grinding ash. Grinding was carried out in an industrial mill for 15, 30, 45, 60 and 75 minutes. The efficiency of the modified ash was monitored for cement paste in terms of rheology and for concrete in terms of consistency, strength and durability. Based on the results we can say that mechanical activation by sorting is suitable for special purposes, but it’s necessary to realise that coarser ash fractions remain unused. When mixing the fractions to ensure matrix density, the efficiency was shown mainly on the durability characteristics. Grinding cause positive effect.
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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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Proposal of production technology for a machine part using a drilling jig
Havránek, Pavel ; Kalivoda, Milan (referee) ; Chladil, Josef (advisor)
The aim of this bachelor thesis is to characterize the selected component, to evaluate the technological design. Further the drilling jig is designed and economical assessment is done. The first part of the thesis deals with the technological assessment of the production of drilling parts and structures. This is followed by familiarization with the technologies used in drilling and component manufacturing. Next sections summarize the rules for the construction of the products and their division. Conclusion of the thesis is devoted to the economic assessment.
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New methods for inner rotary surfaces finishing
Kazdera, Tomáš ; Zemčík, Oskar (referee) ; Zemčík, Oskar (advisor)
Content of the text deals with the methods of finalizing the internal surfaces of revolution. The paper discussed the theory most widely used machining methods that are commonly used in engineering practice. For each methods, are given the tools achieved surface roughness and geometric tolerances. The instruments are assigned to the machine on which the finishing operations are undertaken.
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The proposal of lean production implementation in a industrial enterprise
Nachtmann, Pavel ; Bartošek, Vladimír (referee) ; Jurová, Marie (advisor)
This master´s thesis describes the production process in Japanese enterprise Daikin Device Czech Republic s.r.o. with emphasis on the production schedule, equipment and manufacturing system with elements of lean production. According to the production process analysis at the given production line a new solution of the production process has been suggested to increase production efficiency. This conception has been implemented and compared to the production process before, as well as to the assumed production process after increasing the efficiency.
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Technology of production combinated cutting tools
Rusz, Radek ; Kalivoda, Milan (referee) ; Osička, Karel (advisor)
In the thesis is solved manufacturing technology of step drill from material of cemented carbide. At first is made review of existing shank cutting tool types, after that follows an analysis of cemented carbide tool material. In the next part of thesis is manufacturing technology of this tool, including review of grinding wheels, designed. Output of this work is procedure of program designing for manufacturing this tool in software Numroto. Next output is techno-economic evaluation of step hole manufacture with combined tool and comparison to conventional type of manufacture.
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Planar blade sharpening machine
Kracík, Lukáš ; Tůma, Jiří (referee) ; Pavlík, Jan (advisor)
The aim of this bachelor thesis is to construct a planar blade sharpening machine. Limitation of the design is maximal length of planar blade, 350 mm. First it is necessary to describe method of wood planing and used planers machines. Subsequent chapter contains market guide to planar blade sharpening machines now available. In construction part of this thesis will be proposed three conceptual designs and the most applicable chosen. Then will be selected required components, the machine itself designed and also necessary calculations carried out. Drawing documentation of selected components will be attached.
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