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Evaluation of the fillet weld geometry on process parameters for laser welding of stainless steel
Polášek, Marek ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The present thesis deals with welding of samples to examine the resulting geometry of the weld in dependence on process parameters of the laser. Welding was carried out without additional material using a fibre laser. The material used was stainless steel ČSN EN 17 241. The values of regression coefficients of the resulting graphs show that the changes in the weld geometry - width and depth - vary quite linearly depending on the welding performance. Especially the weld depth is a common requirement in technical practice; the measured results of the experiment can be used to set the process parameters to achieve the desired depth of weld. Some welds exhibit weld defects such as porosity caused by formation of the keyhole due to a large dynamics of the process. The technical-economic evaluation offers a price estimate for one meter of weld for each welding speed used.
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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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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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DEL a.s. – Using of laser technologies
Flimelová, Miroslava ; Bičišťová, Radka ; Brajer, Jan
The aim of the study is to provide sufficient and specific information and documents on the selection and subsequent purchase of a laser source suitable accessories for it . The laser source will be used as a technological tool in building the company's innovation center for technological tests , pilot tests and develop new commercial applications .
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Use schlieren method for displaying flow in laser technologies
Mrňa, Libor ; Pavelka, Jan
It is important to know the flow of gas protective atmosphere for the laser welding degree of protection of the weld pool from the atmosphere and for the interaction between the gas and the plasma plume rising from the keyhole. The gas flow from the nozzle during laser cutting of material has a significant impact on the quality of the final cut. In both cases the schlieren method a very useful tool for understanding the dynamics of gas flow. There were performed multiple experiments to clarify the flow of various kinds of gas (argon, helium, nitrogen) and their dynamics.
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Power Laser Technology at ISI 2013
Mrňa, Libor
The article described the activities of the ISI laser center. It was advanced diagnostics of laser welding process using frequency analysis, the development of a new type of adaptive mirrors for high power laser applications, an apparatus construction for laser hybrid laser-TIG welding, the development of new types of solar absorbers. Contract research for companies was offered.
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Manufacturing of Solar Absorber by Unconventional Methods
Mrňa, Libor ; Lidmila, Z. ; Podaný, K. ; Forejt, M. ; Kubíček, J.
Solar absorbers of flat type have the advantage of relatively simple production, but on the other hand, they have lower thermal efficiency and require perpendicular incidence of solar radiation on their surface. This contribution presents new type of solar absorbers where the above-mentioned disadvantages are reduced while keeping relative production simplicity. The solar absorber is characterized by the creation of the appropriate spatial structure in sheet metal by forming through a technology of drawing in flexible tools. This spatial structure not only increases the heat-transfer surface but also eliminates the need for perpendicular incidence of the incoming solar radiation. The component with this structure is fixed to the rear side of the absorber by laser welding. Inlet holes for the fluid are produced by Flow drill method.
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