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Monitoring the effect of sample treatment in determining selected properties of biofuel
Štenclová, Kristýna ; Lachman, Jakub (referee) ; Lisá, Hana (advisor)
Diploma thesis is focused on the treatment of biofuel prior to combustion and effect of this treatment on the biofuel characteristics. The first part is a review of literature encompassing characteristics of fuel, preparation of samples, methods of analysis of individual characteristics and a presentation of various types of mills. The second part of thesis is experimental. It is an analysis of sample characteristics under various mill settings with regard to the temperature in the mill during grinding.
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The proposal of advanced production technology of steel molds
Opršál, Radek ; Prokop, Jaroslav (referee) ; Kalivoda, Milan (advisor)
The bachelor thesis deals with the modernization of steel mould production in the company P-D Refractories CZ a.s. The thesis focuses on the analysis of current production technology, determination of the bottleneck in production, and the analysis of the possibilities of modification of current technologies. The last part of the thesis proposes the most optimal methods of solution, introduces the technical procedure modified for the new solution and presents the evaluation of the data.
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Technological parameters of abrasive process
Řehák, Pavel ; Bumbálek, Bohumil (referee) ; Prokop, Jaroslav (advisor)
In this work, there is described an abrasive process including technological terms with an identification of motions and a speed of grinding.Then there are described abrasive tools, their distribution and description. In the last part there are introduced some reached parameters of the accuracy and characteristics of the surface structure in dependence on the length of abrasive process.
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An analysis of the heat-affected surface layer after grinding of the bearing rings
Filípek, Timotej ; Kalivoda, Milan (referee) ; Jaroš, Aleš (advisor)
The object of this bachelor thesis is a determination of the causes of burns origin at the surface layer of a workpiece after a grinding process and their elimination. The first chapter is focused on the description of the grinding technology, grinder types and grinding tools. The second chapter deals with the characterisation of the process fluids, their use and suitability depending on the cut conditions and the material. The third chapter explains what a burn is, the causes of its origin and the ways of subsequent elimination of this adverse event. The experimental part – performed in the Schaeffler Skalica, spol. s r.o. company – deals with the origin of the heat affected surface layer due to improper dressing grinding parameters and improper choice of intervals between dressing processes of the grinding wheel. At the experiment two different grinding wheels were used; subsequently, they were compared to each other from the point of view of suitability for the machining process. The final chapter comprises the experimental part assessment and a summary of the findings in this topic.
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The influence of grinding on the limestone properties
Pavlík, Tomáš ; Bednárek, Jan (referee) ; Šiler, Pavel (advisor)
This bachelor thesis deals with dry limestone grinding in the vibratory mill and ball mill. Three different limestone samples were used for milling. Samples were ground in the mills without the addition of surfactants. Several methods of grinding were performed in the vibratory mill. At first, the same weight of limestone samples was ground for different grinding time without any interruption except for one case of grinding with breaks for cooling off the grinding tablet. Another method was grinding of different weights of the same sample. The last one used the same weight of different samples. In the ball mill, sample of one type of limestone was ground for various milling time. The particle size, shape of particles, phase composition and crystallite size were studied for the ground samples. Sieve analysis, laser diffraction analysis, scanning electron microscopy, powder X-ray diffraction analysis and X-ray fluorescence analysis were used to determine these properties. For each mill, the amount of energy consumed for limestone grinding was calculated.
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Machine grinding
Beseda, Vojtěch ; Mouralová, Kateřina (referee) ; Kalivoda, Milan (advisor)
At the beginning of this dissertation an overview of grinding technologies is presented. The following chapter presents a selection of grinding machines from databases and manufacturers’ catalogues. At the end, a case study of grinding processes in a small manufacturing company is analysed. It focused on the action of grinding an internal cylindrical area on thin wall housing. The solution is the adaptation of component´s attachment, the adjustment of the working cycle and the dimensional control according to drawings.
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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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