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Welding of galvanized sheets using hybrid Laser-TIG technology
Antes, Jiří ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
ANTES, Jiří: Welding of galvanized sheets using hybrid Laser-TIG technology This master thesis deals with the welding of zinced deep drawing steel using Laser-TIG technology. The first section of the thesis describes the topic from the theoretical point of view, which includes analysis of welding technologies, influence of used material and application of diagnostic methods. The second part of the thesis is focused on monitoring of welding current impact for weld quality of two types of joints.
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Study of weld plasticity of deep-drawn sheets welded by Laser-TIG technology
Kutil, Petr ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This thesis is focused on laser welding and hybrid laser-TIG welding. The first part contains a brief theoretical description of these technologies. Standard quality and plasticity tests of welded joint are also mentioned. The second, experimental part, centres on the study of plasticity of tailored blanks (made of different types of HSLA steel), that are welded with laser and laser-TIG technology. The aim of the thesis is to assess process parameters effect on weld suitability for following deep drawning operation. Based on the calculated and measured figures obtained from the experiment, the most suitable welding parameters were chosen.
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Examination of degradation frequently repaired shearing and forming tools
Izák, Josef ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis is focused on the renovation of forming tools made of tool steel, their weldability and assessment of the quality of tool repairs. The damaged tool was a part of the cutter from the progressive cutting tool made of Caldie steel. We used micro TIG technology to repair the damage. A total of three types of additional materials were used and investigated to restore the geometry of the damaged edge. One of the main purposes was to evaluate the possibility of extending the life of tools and reducing the implementation of already inefficient repairs. A number of destructive tests were performed for the assessment - macrostructure, microstructure, hardness measurement and EDS analysis.
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Possible design and performance mistakes of welds for resulting chemical threatment by pickling
Hendrych, Marek ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis deals with the issue of surface treatment by pickling. In the research part the pickling technology is described in detail. The next chapters are focused on the TIG welding method and the weldability of austenitic stainless steels. In the experimental part an experiment is carried out focusing on the comparison of weight loss and surface quality depending on the pickling time. Part of the conclusion is the implementation of pWPS documentation for the specified component and a brief manual for customers of pickling plant.
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Loranthus europaeus Jacq. verzus druhy r. Quercus L. resp. Carpinus L. =: Loranthus europaeus Jacq. vs. Quercus L. resp. Carpinus L. genera. /
Kubíček, Jan
A better understanding of host – hemiparasite association can lead to deepening and improving strategies, which would result in a long-term sustainability of their mutual balance or prosperity of urban and forest vegetation growth. The aim of the thesis is to describe and explore periodicity and dynamics of hemiparasite (Loranthus europaeus Jacq.) on various host woody species (Quercus petraea (Matt) Liebl., Carpinus betulus L., Prunus spinosa L.), options of the host support and means of a careful removal of parasite. However, to determine the progress of the infestation in time was the primary aim of the thesis. The research has been carried out in Brno – Kohoutovice and National Park Podyjí. The emergence of both hemiparasite´s and host´s phenophases were mutually compared in the critical conditions. The variation of the growth modules of mistletoe was compared in relation to the host species. The growth and fruit yield of the host and hemiparasite were analysed after the application of fertilizer based on the variations of the mineral content of leaves and soil. Between the years 2011-2015, 1599 stems were monitored for the degree of infestation by mistletoe. The results indicate that the vitality of the hemiparasite depends on the type of host. Fertilizer application improved the growth of the host. Arboricide application on the leaves of the hemiparasite was proven to be efficient. The abundance of hemiparasite increases with the increasing diameter at breast height (DBH), time and mutual interaction. The amount of hemiparasite slightly increases with the lower DBH. However, with the increasing DBH the mentioned phenomenon decreases. The trees with high DBH even show the decrease in the mistletoe infestation in time. Nevertheless, the decrease was accompanied by negative effect – gradual reduction of the crown and loss of the host tree branches. Hemiparasite is able to eradicate the whole stand. Hence, the necessity of paying attention to this issue since the young age of the individual trees. It is necessary to protect trees against stress aspects which can accelerate the negative effect of hemiparasite on the host.
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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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Thermal spray by electric arc
Eliáš, Vojtěch ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
This thesis deals with the issue of thermal spraying by means of an electric arc. First of all, a theoretical part is processed using a literary study dealing with corrosion and thermal spraying technology. The experimental part contains a description of the technological procedure and evaluation of four thermally sprayed samples. Zinacor 850, consisting of 85% zinc and 15% aluminum, was used as a coating. The evaluation involves measurements of thickness, adhesion and roughness as well as the macro-structural analysis of the coating. Two samples showed unusually low adhesion, and all samples also had a large fluctuation of the measured thicknesses. This was also confirmed by the macro-structural analysis, which showed that the sample with low adhesion also had high porosity. These defects may have multiple causes, but the recommendation for further practice is to reduce the spraying distance from the base material.
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Renovation of casting molds by laser cladding technology
Cicha, Tereza ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The diploma thesis deals with study of laser cladding technology and possibilities of its use in renovation of casting molds made of hot-work tool steel. The theoretical part describes methods of laser cladding, testing methods and characteristics of the base material and its heat treatment. In the experimental part the test clads, and the metallographic samples were made. The samples were evaluated in terms of macrostructure and microstructure, especially clad geometry, dilution, and defects like pores and cracks. Microhardness was also measured. In conclusion a technical and economic evaluation was performed.
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Evaluation of quality welds on chains for harvester
Teuer, Tomáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis examines the influence of setting welding parameters and welding process on the resulting structure and strength of the welded joint of harvester chains. The theoretical part discusses the problem of weldability of pine steels by using method “135” with the possibility of destructive or non-destructive testing of welded joints. In the practical part, this matter is examined on a specific weldment, the harvester chain. Cross member with a cube welded in two ways by method 135, followed by an assessment of the performance of welds. The results of the evaluation are written down in the manual.
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Cryogenic cell for study of water ice in ESEM microscope
Krutil, Vojtěch ; Kubíček, Jaroslav (referee) ; Urban, Pavel (advisor)
The presented thesis focuses on designing a cryogenic cell for the study of water ice in an environmental scanning electron microscope (ESEM). This cell allows the study ice in the temperature range 80 K – 300 K in a nitrogen gas environment with a pressure of up to 400 Pa. The cell is cooled by a flow cooling system, where liquid or gaseous nitrogen is used as a refrigerant. The cell consists of a double-walled vessel with vacuum insulation, a flow-through heat exchanger, a sample well, and a cooled cell lid. The heat exchanger was designed to be able to dissipate the heat load at the level of 1 W. The exchanger is equipped with an electric resistance heater with an output of approximately 60 W, enabling heating of the sample at speeds of up to 100 K·min-1. The design also includes an LN2 gateway located on the door of the vacuum chamber of the microscope, to which the capillaries of the heat exchanger for the intake and outlet of refrigerant are connected. During the experimental verification of the cryogenic cell in the test vacuum chamber with a pressure of GN2 ~ 400 Pa, the limit temperature of 77.5 K on the sample well was reached.
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