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Use of the Laser-TIG hybrid method in the automotive industry
Mrňa, Libor ; Šebestová, Hana ; Horník, Petr ; Antes, J. ; Kutil, P. ; Křápek, L. ; Iván, L.
High demands are placed on the joining of body parts in terms of strength and consistent quality. Simultaneously, production time minimizing is required. In addition to the most common spot resistance welding, laser welding is often used. This provides high welding speed as well as good strength. Of course, there is a general desire to increase the overall strength of the body-in-white while reducing production costs, which are conflicting requirements. The only way forward is to use modern steel materials (HSLA steels, DP steels, etc.) and to use new, more advanced joining technologies. The paper presents possibilities of hybrid Laser-TIG welding technology.
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Welding of heterogeneous joints by laser
Charvátová, Eliška ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
This diploma thesis deals with welding of two dissimilar materials by laser. The samples were welded by direct beam guidance and wobbling, with and without using high alloy filler material and with the use of a diffusion barrier in the form of nickel. Welding was done with different shielding atmospheres. Nondestructive (VT, PT, UT-PA, RT) and destructive tests were performer (tensile test at room and elevated temperatures, microhrardness). Metalography was suplemented by EDX analysis of selected elements.
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Modification of a laser welding system for welding materials releasing excessive amounts of fumes
Kohout, Jaroslav ; Sigmund, Marian (referee) ; Mrňa, Libor (advisor)
The thesis deals with the implementation of a suction system for laser welding. The specific product is grate used for outdoor drainage. The original GMAW production technology is to be replaced by a laser. During the welding of S235JR steel, a significant development of exhaust gases was observed, which subsequently made the actual process impossible. Practical experiments were performed and evaluated using tensile testing and metallographic cut. Based on the results, the optimal position of the suction nozzle and welding parameters were recommended. The obtained values were re-verified by experiment. Furthermore, a suitable extraction device was proposed and an economic evaluation was performed.
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Optimization of welding parameters during laser welding with additional cold wire
Venc, Jan ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This diploma thesis deals with the optimization of process parameters of welding a drainage channel using a laser beam with an additional cold wire. This channel is made of austenitic Cr Ni stainless steel X5CrNi 18-10 (1.4301, ČSN 17 240) with a sheet thickness 1,5 mm. Mechanical properties of samples were checked by using transverse tensile test. Subsequently, the samples were macroscopically inspected focusing on dimensions of the weld and the presence of weld defects. Finally, the structure of the weld metal and fundamental material was evaluated by using microscopic control. Based on evaluation tests, the optimal welding parameters were recommended.
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Feasibility study of welding for stainless part „ guide rail"
Vaverka, Jiří ; Mrňa, Libor (referee) ; Sigmund, Marian (advisor)
Robotization of industry is very important in these days. It is possible to replace human workers with robots and because of that make manufacturing faster. This master’s thesis includes feasibility study of robotic welding for stainless steel part guide rail. Quality of robotic welding was evaluated on testing pieces. Robotic welding was 88,5 % faster than current welding method. Costs of manufacture of one piece were 40 % cut.
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Friction welding of materials
Chrást, Daniel ; Sigmund, Marian (referee) ; Mrňa, Libor (advisor)
Práce se zabývá zkoumáním svárů z materiálů AISI 316L a TI GR2. Svár je zhotovený rotačním třecím svařováním. První část práce je literární rešerše na téma rotačního svařování třením. V druhé části práce jsou uvedeny výsledky zkoumání svařovaných spojů. Byla zkoumána jejich makrostruktura, mikrostruktura, mikrotvrdost ve všech oblastech svarového spoje, materiály prošly zkouškou chemického složení a svarový spoj byl vystaven tahové zkoušce.
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Working of semi-finished product for laser welding
Černý, Jan ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The thesis deals with the technology of laser welding and preparation of semi-finished products for laser welding for serial production. The theoretical part deals with the physical nature of the laser, different types of lasers, welding technology, preparation of welded surfaces, safety of work with lasers and basic division of corrosion resistant steels. The practical part deals with the assessment and evaluation of the proposed technologies of cutting blanks for laser welding. In the practical part, roughness, flatness and macrostructure tests were performed and evaluated.
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Comparison of flame and fusion laser cutting of material DC01
Krejčiřík, Marek ; Horník, Petr (referee) ; Mrňa, Libor (advisor)
This thesis is focused on the technology of laser cutting together with edge roughness for low carbon steel material DC01. The thesis is divided into theoretical and practical part. The theoretical part examines laser itself and contains a physical description of the laser beam with the laser construction, division according to the active environment or the occurrence of laser devices in today’s engineering industry. The last part of the theoretical research is aimed to the surface roughness, its parameters and the measuring technology. The practical part is focused on the comparison of the edge roughness of material DC01 after laser cutting with the usage of flame and fusion. The measured parameters of roughness were further compared with the norm ČSN EN ISO 9013.
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Procedural parameters at Inconel 625 cladding
Hrádek, Jan ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
The research is focused on cladding of inconel 625 using the MAG - CMT method. It was found that welding without an oscillation does not create the necessary geometry to establish additional layers. When welding with an oscillation, it was researched that the current between 150 and 200 A appears most appropriate in the synergistic mode for welding inconel 625. The resulting weld bead was made at a current of 190 A with pulse dynamics correction set to -4 and correction of arc length to +10 and welding speed of 315 mm per minute.The weld bead was not ideal mainly due to insufficient height. The improvement of results could be achieved by set oscilation with fluent change in acceleration. Because of the time options and difficulty of programming it was used only constant speed for all experiments.
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