|
|
Simulation of geometry of key hole depending on the welding parametrs in laser deep penetration welding
Křivan, Miloš ; Šarbort, Martin (referee) ; Mrňa, Libor (advisor)
The diploma thesis is focused on simulation of keyhole creation in laser deep penetration welding and on the effect of welding parameters on the geometry of keyhole (weld). With reference to this issue theories of keyhole creation are described. 2D simulation model that is created in mathematical software Matlab is verified pursuant welding results of non-alloy constructional steel 1. 0122 and stainless steel 1.4301. Effect of welding parameters on the geometry of keyhole and on the quality of weld is investigated through the welds in non-alloy steel 1.0122.
|
|
|
Study weld porosity aluminum alloy 5000 series during hybrid welding Laser-TIG
Drápela, Petr ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This bachelor thesis is aimed on studying weld porosity of aluminium alloys made by laser-TIG technology. Theoretical part deals with welding methods and their parameters, capabilities and usage. Methods are investigated separately then as a unit. At the end of the theoretical part there is summary about welding aluminium alloys and their properties. In experimental part it is made eleven testing welds on sheet metal from aluminium alloy EN AW-5754 H111, thickness 5 mm. After this sizes of welds are measured. From these sizes dependences welding current to input heat Q are made. Final part concerns analysis of welding defects and final evaluation optimum welding parameters.
|
|
|
Comparison of properties of butt joints welded by laser and plasma for austenitic and ferritic stainless steel
Zajíc, Jiří ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The thesis is focused on evaluation and comparison of welds made by welding technologies using laser and plasma. For the purpose of comparing those technologies, were chosen austenitic stainless steel x5CrNi18-18 and ferritic stainless steel X6Cr17. These materials were chosen for their diversity in properties gained by high temperatures that go along with most welding processes. First part of the thesis is focused on description of welded materials and technologies of laser and plasma welding. In following experimental section, the thesis is focused on evaluation of welded samples, made for this purpose. Samples were examined for metallography, specifically macrostructure and microstructure. Followed by tensile test of mechanical properties and microhardness test.
|
|
|
Comparison of properties of butt joints welded by laser and plasma for austenitic and ferritic stainless steel
Zajíc, Jiří ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The thesis is focused on evaluation and comparison of welds made by welding technologies using laser and plasma. For the purpose of comparing those technologies, were chosen austenitic stainless steel x5CrNi18-18 and ferritic stainless steel X6Cr17. These materials were chosen for their diversity in properties gained by high temperatures that go along with most welding processes. First part of the thesis is focused on description of welded materials and technologies of laser and plasma welding. In following experimental section, the thesis is focused on evaluation of welded samples, made for this purpose. Samples were examined for metallography, specifically macrostructure and microstructure. Followed by tensile test of mechanical properties and microhardness test.
|
|
|
Study weld porosity aluminum alloy 5000 series during hybrid welding Laser-TIG
Drápela, Petr ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This bachelor thesis is aimed on studying weld porosity of aluminium alloys made by laser-TIG technology. Theoretical part deals with welding methods and their parameters, capabilities and usage. Methods are investigated separately then as a unit. At the end of the theoretical part there is summary about welding aluminium alloys and their properties. In experimental part it is made eleven testing welds on sheet metal from aluminium alloy EN AW-5754 H111, thickness 5 mm. After this sizes of welds are measured. From these sizes dependences welding current to input heat Q are made. Final part concerns analysis of welding defects and final evaluation optimum welding parameters.
|
|
|
Possibilities in monitoring of laser welding process
Horník, Petr ; Mrňa, Libor
With increasing demands on the quality of the welds, it is usual to apply automated machine welding with monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we develop optical methods of monitoring the process based on analysis of radiation of laser-induced plasma using Fourier and autocorrelation analysis. Observation of keyhole inlet opening is partially possible through a coaxial camera mounted on the welding head and the subsequent image processing. A high-speed rear camera to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. Shielding gas flow can be visualized using schlieren method.
|
|
|
Simulation of geometry of key hole depending on the welding parametrs in laser deep penetration welding
Křivan, Miloš ; Šarbort, Martin (referee) ; Mrňa, Libor (advisor)
The diploma thesis is focused on simulation of keyhole creation in laser deep penetration welding and on the effect of welding parameters on the geometry of keyhole (weld). With reference to this issue theories of keyhole creation are described. 2D simulation model that is created in mathematical software Matlab is verified pursuant welding results of non-alloy constructional steel 1. 0122 and stainless steel 1.4301. Effect of welding parameters on the geometry of keyhole and on the quality of weld is investigated through the welds in non-alloy steel 1.0122.
|
|
|
Adaptive optics for control of the laser welding process
Mrňa, Libor ; Šarbort, Martin ; Řeřucha, Šimon ; Jedlička, Petr
The laser head with fixed focus optics is commonly used for the deep penetration laser welding. In such case the geometry and position of the beam waist are defined by the focusing lens. If the laser beam incident on the focusing lens is not well collimated but divergent and its divergence can be varied by proper adaptive optical elements, then also the geometry and position of the focus will be changeable. In this way it is possible to affect the energy coupling from the laser beam to the keyhole walls and thus to control the geometry and quality of the weld. In this paper we present a theoretical and numerical study of the beam shaping by adaptive optics and its influence on the weld quality. For the CO2 laser welding machine the adaptive optics was realized by a deformable mirror and its effect was tested also experimentally. For the solid-state laser welding machine we designed a laser head with changeable distance between the optical fiber and the collimating lens and we simulated its performance.
|
|
| |
guest ::
