Issued topics of Doctoral Study Program:|
- Application of modern technologies for production of complex shape surfaces
Research and development of technologies for special-purpose shell components which could be used as bone replacement or implants. The aim of research is to propose a technology of prototypes creation with support of reverse engineering, rapid prototyping and CAD/CAM. Technology could be potentially applied in orthopaedics and surgery for special trauma cases. Significant contribution of this research may lie in a lesser incision into patient body, reduction of femur bone cutting, considerable preservation of own bone material and reduction of the time and costs in the operation.
- Application of single-point forming at CNC machines.
Single-point forming is a production technology, which uses diagrams of limit formability of materials, simple forming tools and CNC machines to produce parts or prototypes using point to point forming. This procedure can get a fully functional prototypes made of metals. The aim is to analyze the formability of a selected material, make a CNC technological programme and experimental verification of the production technology.
- Manufacture and properties of cast ceramic cores based on ethyl silicate
For the production of demanding castings for the hydropower (impeller and distribution wheels of pumps) the ceramic cores are used which creates in the castings often very complex inner cavities for the flowing fluid. A primary requirement is not only to achieve high surface and internal quality of the casting, but also to achieve the lowest possible surface roughness inside the channel. Its roughness directly influences the resistances against the liquid flow and thus the efficiency of the given pump. Ceramic cores used today are produced either by casting or pressing into moulds. Ceramic cores centrifugally cast into coreboxes use as a binder the gelation process of ethyl silicate or colloid solutions based on water or alcohol. Pressed cores are usually not applicable for some types of pumps and, in particular, they are limited by a maximum size of cores. Gelation of colloid solutions used in the production of cast cores results from the pH control of the binding liquid with the aid of alkaline accelerators. The work is aimed at optimizing the gelation process of colloidal silica or colloidal corundum based on ethyl alcohol or water and also optimizing the entire core production technology to achieve the handling and final strength after the annealing necessary for the production of demanding ceramic cores for castings for power engineering and other engineering.
- Milling of shaped surfaces produced on CNC machine tools
Permanent pressure on manufacturing expenses and reduction of manufacturing costs and global economy trends lead to modern technologies and tools using HSC (High Speed Cutting), HFC (High Feed Cutting) and HPC (High Performance Cutting). The technologies meet the criteria and reduction of cooling fluid in production. The main subject of the research work will be a study of force loading and thermal impact on cutting tools, work-pieces and machine parts, including of a study analysing the wear of cutting tools, integrity of machined surfaces and temperature deformations of machine parts.
- On the production of advanced implants and their insertion technologies
Research and prototype production of advanced implants, especially based on 3D printing from metal powders and their implementation technologies with computer-aided machine technologies.
- Precipitation of intermetallic phases in duplex austenitic-ferritic duplex steels
Intermetallic phases are precipitated in the duplex steels during cooling of castings and ingots after their solidification, after reclaiming welding or after long-term exposure of the material under high temperatures. These are the intermetallic phases of the sigma phase type, the χ phases or the Laves phases. Their precipitation degrades the steel properties both from the point of view of mechanical as well as utility properties. Especially the plastic properties and steel toughness are significantly reduced. The work aims at describing the basic conditions and precipitation mechanisms of intermetallic phases in relation to the production conditions and chemical composition of duplex steels. An attention will be paid to the structural stability of the intermetallic phases in the Fe-C-Cr-Ni systems. This is the current issue of the field of physical metallurgy, which will be dealt with in the framework of the research project of the Technological Agency of the Czech Republic.
- Progressive technologies of five axes machining at machining centres
Modern technologies of 5-axis machining are very frequently asked machining operations at modern CNC centres. 5-axis machining has been used in aerospace applications for many years but it is only recently that the toolmaking industry has shown similar interest. The main advantage of 5-axis machining is the ability to save time by machining complex shapes in a single set-up. Additional benefit comes from allowing the use of shorter cutters that permit more powerful and more accurate machining.
- Segregation processes during solidification of casting from high-alloyed chromium and chrome-nickel steels
Resulting properties of castings from austenitic steels are significantly influenced by the solidification time that affects the size of the primary grain as well as the layout of elements within the dendrite and its parts with regard to the last solidification points in the interdendritic melt. During solidification an intensive segregation of all admixtures occurs in the melt, which causes a whole range of serious metallurgical defects and it has also a significant influence on subsequent precipitation of carbides and intermetallic phases. Chemical heterogeneity of castings is manifested both in the microvolume (microsegregation), and in the macrovolume (macrosegregation) of the casting. Chemical heterogeneity then affects the structure and mechanical properties of the casting. The proper work is aimed at modelling of chemical and phase composition in dependence on solidification conditions. Based on modelling and the experiment the work aims at determining the indices of segregation of admixtures and the extent of dendritic segregation and macrosegregation in dependence on the speed of the shift of the solidification queue and temperature gradients in the melt and the solid phase during solidification. This is the current issue of the field of physical metallurgy, which will be dealt with in the framework of the research project of the Technological Agency of the Czech Republic.
- Study of the efefects of deformation rate and temperature parameeters on formability of Al alloys
On selected Al alloys, which are used in the manufacture of components for the chemical, aircraft, and nuclear power industries, the non-uniformities of the distribution of deformations and structural changes shall be assessed, and the effect of increased temperatures and deformation rates on the formability of these alloys shall be evaluated. Constitutive equations for the stress-strain curves will be written as materials models to be used in the calculation models of current software programs
- Studying the influence of speed parameters on formability of deep drawing steels
On selected deep drawing steels assess the uneven distribution of deformation and structural changes and to assess the effect of strain rate on their formability. Create a constitutive equations for the stress-strain curve as a suitable material models into computational models of current programs.
- The limiting strain of carbon steels in cold bulk forming
The selected low-carbon steels, which are used for forming the coupling parts volume and machine parts, to assess their plastic and structural changes at high deformations and limit the influence of strain rate. Create a constitutive equation for stress-deformation curves with the limiting conditions limit deformation.
- Tool wear and methods for tap threading performance enhancements.
Taps keep an irreplaceable position among other tools for threading in manufacturing technologies. Their modernization today gathers improvements of their geometry, powder metallurgy applications for the tool core and applications of hard and wear-resistant coatings. The aim of the work is a modern drill bit for threading of structural steel, especially in hardened state.
- Tool wear of cemented carbides cutting inserts and methods for their turning performance enhancements.
Cutting inserts keep an irreplaceable position among other tools for turning in manufacturing technologies. Their modernization today gathers improvements of their geometries, powder metallurgy applications including the phase interphase and applications of hard and wear-resistant coatings. The aim of the work is a modern cutting material for turning of structural steel, especially in hardened state.
- Twist drill wear and methods for drilling performance enhancements.
Twist drills keep an irreplaceable position among other tools for drilling in manufacturing technologies. Their modernization today gathers improvements of their geometries, powder metallurgy applications for the tool core and applications of hard and wear-resistant coatings. The aim of the work is a modern drill bit for drilling of structural steel, especially in hardened state.