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Hot dip galvanizing of the steel construction
Pometlo, Stanislav ; Vyplašil, Evžen (referee) ; Kubíček, Jaroslav (advisor)
This master´s thesis deals with hot dip galvanizing of steel constructions and their protection from corrosion. This work describes the origin of corrosion of steel and its corrosion in different areas and presents degreasing and pickling before hot dip galvanization. It describes possibilities of making zinc layer by the wet and draw method of hot dip galvanization. Furthermore, it puts forward reactions between zinc and iron, possible defects of the zinc layer and influence of the hot dip galvanizing on the steel constructions. The experimental part examines the influence of the hydrogen charging on the material and the time of the flux operation on the quality of layer. The work further analyses the changing of mechanical properties of steels Hardox 500 and Weldox 700 as a result of the hydrogen embrittlement during pickling by the hydrochloric acid.
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Inspection of welded joints of loading ramps
Ertl, Roman ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
This master's thesis is focused on problem of welding of loading ramps and inspection of their welded joints. The aim of this thesis is to inspect the welds of loading ramps with regarding to the appearance of defects. The literature review of the research issues of the MIG welding technology and welding of aluminium and its alloys is described in this thesis. There is also described destructive and non-destructive inspection of welds that can be applied to inspection of loading ramps. Theoretical description is followed by an experimental part of the thesis. Experimental part is focused on the three destructive tests (the tensile, the macroscopic and the hardness test) of samples of loading ramps, which are made of EN AW-6005A T6.
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Welding of high strenght steel by laser
Číp, Tomáš ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This project, elaborated within the engineering studies (code of field of study: N2301), presents experiment of welding of high-strength steel by laser. In this project, the samples of high-strength steel DOMEX 420MC will be welded by laser welding method and the welded joints will then be compared with welds made by MAG method. The theoretical part of this project summarizes the following key words in individual chapters: lasers, technology of welding of steel using laser, welding by MAG method, steel with higher strength, types of defects and check of welded joints. The practical part contains description of and assessment of mechanical tests of welded joints – weld bending test and transverse tension test. Further on, the tests of macrostructure and microstructure of welded joints were conducted and assessed. Final results of whole experiment are reviewed at the end of my diploma thesis.
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Laser welding of steels in automotiv industry
Paleta, Petr ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
In the automotive industry is beginning to replace the resistance spot welding by laser welding. The bachelor thesis was an analysis of laser welding methods, especially the method of remote welding, which is used for the experiment. Furthermore, the use of laser welding was described. We have also suggested the general technological process of welding. The experimental part was carried by metalografic cut of welded sample, which was evaluated by its macrostructure and microstructure.
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Comparison of properties parameters of laser solid state
Bazalová, Lucie ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The bachelor thesis deals with the characteristics, properties, parameters and application areas of solid-state lasers. It provides the explanation of the principle of laser beam and the associated individual types of lasers. This is followed by a more detailed division of solid-state lasers and their individual applications. Among these applications, more space is devoted to laser welding, where the main objective is to design a laser welding facility for steel welding up to a thickness of 10 mm.
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Surface treatment by wet paiting
Fical, Karel ; Žák, Ladislav (referee) ; Kubíček, Jaroslav (advisor)
Protection of various coating materials is today very important, both in terms of aesthetic, functional and, especially corrosion. Corrosion annually causes significant damage to metal structures and degradation of material can cause a total damage of the parts or the whole structure. When appropriate choice of coating materials can suppress the corrosion and its manifestations delay up to several years. Today, the protection of organic material coats the most common way and takes 80 to 90% of all coatings. When selecting paints and their subsequent applications we care about the material properties of the edit, its functional use, the environment in which they will be located and the properties of paint itself. To achieve satisfactory properties, it is necessary to create a technological process for the specific case.
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Optimalization of bus roof glueing
Jaroš, Vojtěch ; Halamík, Tomáš (referee) ; Kubíček, Jaroslav (advisor)
The main object of this master´s thesis is to increase productivity glueing and lowering the weight of the bus roof while maintaining its toughness. The first part describes the present glueing technologies. Subsequently, there is adduced theoretically various hypothesis about the glue seam. The proposed solution is to use the glue containing accelerators. Two glues from the companies DINITROL and SIKA are suggested and compared. The following chapter details the suggested technology and describes its possibilities. The final part presents the project of ultralight roof made from sandwich panels.
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Laser welding of steels
Křivan, Miloš ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The project elaborated within the bachelor‘s degree field of B-STI Mechanical Engineering is focused on the problems of laser welding of steels. The theoretical part of this project deals with lasers, methods of laser welding, effects of welding parameters on weld quality and the weldability of steels. In the practical part sheets that were made of S355J2G3 and S355J2C+N steels were butt welded. The aim of the practical part was a determination of such welding parameters as the welded joints meeting the quality requirements according to ČSN EN ISO 13919-1 standard and the hardness requirement less than 380 HV10 according to ČSN EN ISO 15614-11 standard. The tests of the macrostructure of the welded joints were conducted and assessed and the hardness of the welded joints was measured.
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