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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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Compare weld from CO2 laser and fiber laser
Leidorf, Michal ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The project compares the technology of welding of CO2 laser and fiber laser in terms of engineering study, the welds will be made by same welding conditions on two materials (S235JRG2 a X5CrNi 18-10), by using different protective gases (Helium and Argon). In the terms of literal background research both the technologies and questions of laser welding are described. The geometry of welds is carried out in the experimental part. The final results of the experiment are concluded at the end of the diploma thesis.
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Optimization of the laser weld of overlap seam for zink layered sheet metal
Plíšek, Roman ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This diploma thesis deals with the experiment of welding galvanized sheets using fiber laser. The experiment is based on testing of welds lap joints with different gap between the welded parts. Theoretical part of this diploma thesis describes the principles and different types of lasers, laser welding technology, welding defects, galvanizing and inspection of welded joints. In the experimental part of the thesis welding tests and analysis of the results of the experiment have been realised and evaluated.
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Optimization of laser welding of carbide cutting plates on a support tube
Franko, Matej ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
My thesis is considering the options of manufacturing of the core drill. One of these options is technology of the laser welding, which was described in details in the theoretical part of this thesis. In applied part of this thesis there were experimentally manufactured two pieces of core drills by using Yb-YAG fibre laser technology. One core drill was used for testing of the welding parameters and in the next step, these parameters were applied in real working conditions and were evaluated in final. Result is written down in the final part of my thesis. The second core drill was welded using the best values measured in the fixture, which was especially designed for this purpose.
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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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Crank mechanism with a high mechanical efficiency
Drápal, Lubomír ; Tůma, Jiří (referee) ; Páv,, Karel (referee) ; Píštěk, Václav (advisor)
This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.
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Weldig of the different type of steel by the Yb-YAG laser.
Kopecký, Lukáš ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
Diploma theses is focused on welding experiment of maraging steel by use Yb-YAG laser. Experimet is based on testing of combination steel 11321 and maraging steel. Domex420MC, Domex720MC a QSE380. In theoretical part there are described laser technology of welding, weld defect, maraging steel and inspection of welded joints. In experimental part there are porposed test and made mechanical test of weld as transverse tensile test, bend tests, Erichsen cupping test, Vickers hardness test and makroscopic and microscopic examination of welds. In conclusion there are analysis of the experiment results.
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Weldig of the different type of steel by the Yb-YAG laser
Chlád, Luboš ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The master's thesis presents an experiment of welding of high strength steel Docol 1200 M and of steel DC01 by the fiber Yb-YAG laser. The experiment is based on testing welds which were made during the experiments. The lasers, laser technologies of welding, steels of higher strength, tailored blanks technology and testing of welds are described in the theoretical part. The practical part contains description and evaluation of tests of welds – transverse tension test, Vickers hardness test, Erichsen cupping test and macrostructure and microstructure test. The final evaluation results of the experiment are presented in the conclusion of the master's thesis.
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