National Repository of Grey Literature 45 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Production of thinwall iron castings
Kryštůfek, Tomáš ; Kaňa, Václav (referee) ; Roučka, Jaromír (advisor)
This diploma thesis is focused on production and problems in production of thin-walled ductile iron castings, especially in the inoculation process. The focus is on the influence of elements on the structure and mechanical properties of ductile iron and as well as the influence of some elements, that are commonly used in inoculation alloys. Furthermore, the factors that affect the production technology are written, i.e., solidification rate, wall thickness, cooling rate, and factors used for affecting the thin-walled castings production, i.e., the use of insulating moulding compounds and increasing the graphite nodule count. At the end of the theoretical part, important production processes are analysed, namely inoculation and spheroidization. The experimental part is focused on influencing the structure and mechanical properties using several types of inoculants of different chemical compositions, whereas the tested thicknesses of the test plates are 3-, 5- and 8-mm. Hardness, tensile strength and ductility are evaluated on these plates. Finally, the volume of ferrite in the structure, shape and size of the graphite nodules were examined.
Manufacturing of aluminium alloy castings in sand mould
Exner, Zbyněk ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
The thesis theoretically deals with research activities in the field of molding mixtures, description and division of aluminum alloys for castings. Furthermore, the thesis presents the process of production of the cylinder head of the internal combustion engine Jawa 50, from the design of a 3D model and its production by 3D printing to its casting from aluminum alloy EN AC-46000. Molds from bentonite, self-hardening and oil-bentonite molding mixtures were used to cast the test casting. To complement the experiment, the casting was also made using the lost-wax casting method. For the production of wax models, it was necessary to make a mother mold. Subsequently, two different ceramic shells were made. The first one was designed to cast only one casting, the second one, with a different orientation of the models to the inlet, allowing to cast two pieces of castings at once.
The influence of cast iron inoculation with bizmut containing inoculant on structure and mechanical properties
Nyékyová, Dominika ; Navrátil, František (referee) ; Roučka, Jaromír (advisor)
The diploma thesis deals with the modification and inoculation of cast iron with spheroidal graphite, the influence of the chemical composition on the shape and size of the graphite nodules and ferrite/perlite ratio in the structure. The aim of the practical part was to determine the effect of inoculant containing bismuth (SMW 605) on microstructure and mechanical properties of ferritic ductile cast iron GJS 400-15. The dissolving time of mold inoculant was further investigated. The samples were subjected to a tensile test, Charpy impact test, hardness test and graphite morphology and ferrite/perlite examination using standard ČSN EN ISO 945-1.
Surface quenching of ductile cast iron
Neduchal, Bronislav ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
This diploma thesis is focused on the surface hardening of cast irons with spheroidal graphite. The work describes a theoretical analysis of the structure and properties of cast irons and individual methods suitable for surface hardening. The practical part describes the production of cast iron castings with spheroidal graphite, on which the surface hardening is performed, tensile test, hardening of produced castings by induction and laser surface hardening, preparation of samples for measuring microhardness and metallographic analysis of metal structures.
Proposal of casting technology for cooper alloy castnig with regard to their quality and productivity of fininishing oprations
Herzán, Jiří ; Lána, Ivo (referee) ; Roučka, Jaromír (advisor)
This paper is created based on the real situation in Armatmetal s.r.o. Based on customer requirements and possible reduction of finishing operations at the end of production in the foundry. The foundry technology of gravity casting into sand molds is changed to gravity casting into metal mold. To change technology at Armatmetal s.r.o. two types of castings were selected. The "Kloub 55 s vidlicí" casting was selected by the customer to test the new technology. Casting "Klínová koncovka KN10" was chosen by Armatmetal s.r.o. because of the structural design of the casting and the high repeatability of production. Castings are the subject of the paper. The diploma thesis includes methods of solving the elimination of foundry defects occurring on a complicated casting " Kloub 55 s vidlicí". The main aim of the thesis is to assess the technical-economic contribution of the change of foundry technology of the casting " Klínová koncovka KN10". The paper also includes a complex comparison of the current and new technology production with related problems and their solutions.
Prediction of mechanical properties of lamelar iron castings by means of numerical simulation
Filipek, Szymon ; Hrouzek, Petr (referee) ; Roučka, Jaromír (advisor)
The aim of this thesis was to assess the degree of conformity between the mechanical properties evaluated by numerical simulation in software MAGMA5 and the measured values of hardness and ultimate tensile strength of lamellar graphite iron castings. The theoretical part of this thesis deals with the classification of cast iron, structural components of lamellar graphite iron, and the factors defining the resulting mechanical properties of the material. The practical part presents an attempt to find empirical dependencies between input parameters and results evaluated by simulation software. At the end, an analysis of the correlation between reality and simulation software is performed.
Influence of repair welding by elevated temperatures on structure and hardeness of lamelar grafite iron castings
Procházka, Jan ; Bouška, Ondřej (referee) ; Roučka, Jaromír (advisor)
The master‘s thesis deals with the influence of the thermal cycle of welding with preheat on castings made of grey cast iron to change the hardness. The thesis deals with the classification of graphitic cast irons, their structure, properties and influences they have on the formation and transformation of the structure. Emphasis is placed on chemical composition and structure stability at elevated temperatures. The practical part deals with the investigation of the effects of casting repair on the decrease of hardness measured in the foundry Heunisch Brno.
Utilization of Thermal Analysis for Casting Quality Prediction by Means of Numerical Simulation
Malatin, Richard ; Krutiš, Vladimír (referee) ; Roučka, Jaromír (advisor)
This work deals with problem of analyzing cooling curves of ductile iron and discovering possibility to predict shrinkage tendency of melt from thermal analysis results. This work was executed in foundry production conditions where obtained data from thermal analysis data linked to experimental castings where amount of shrinkage was estimated. Data were analyzed and looked for correlations between acquired thermal data and shrinkage defects.
Influence of thermal treatment regime of Al-Si alloys on mechanical properties
Letovanec, Juraj ; Kolmačka, Marek (referee) ; Roučka, Jaromír (advisor)
The aim of this thesis is influence of precipitation hardening regime, specifically quench rate, on mechanical properties of aluminium alloy A356 (AlSi7Mg0.3). Samples were after solution treatment quenched into water with different temperatures and age hardened. Tensile strength tests, hardness tests and microstructure observations were done after heat tretment.
Proposition of casting technology of aluminium manifolds cast by tilt method
Spáčil, Ivo ; Kaňa, Václav (referee) ; Roučka, Jaromír (advisor)
Description of the theoretical factors for casting into metal molds. For thin-walled castings it has turned out that the most advantageous method is tilt casting. Tilt casting reduces the turbulence of the melt and reaches a directed solidification. Two molds were tested and measured for the experiment. During measuring the temperature regime was established lower temperature of the pouring basin than the other parts of the mold, which could cause a many of defects. The verification of mold technology has been performed. To achieve the accuracy of the casting, it is necessary to respect the different shrinkage according to the shape of the casting.

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