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Tramways in cities often ride in track curves of a small radius, which is followed by an increased effect of the vehicle on the track by the rail - wheel contact. Exactly with the aim to reduce these undesirable effects we designed a tram bogie with steered wheelsets. Moreower, for the vehicle passability trough strongly curved track inproovement, we proposed spcific, double treaded wheelset and coresponding track section. This invention is also registered under Patent Aplications Nr. a201701589 and Nr. a 201706685. A comparison of safety against derailment results for a tram vehicle running through a S-curve with considering of tread change is given in this paper. Three cases are compared: the first case is a T3 tram vehicle with original bogies, the other two cases represent a tram vehicle, which uses proposed inventions. Two ways of bogies placement under the vehicle body are investigated.

Nowadays, ever increasing demands are being made on equipment and machine structures. This fact negatively affects their lifespan, reliability and security. Internal damping is caused by material malfunctions in the microstructure, thermoelastic effects, movement of dislocations or the effects of swirling currents. This paper deals with microstructure, chemical composition and mechanical properties of ductile iron. These data are required as input parameters for computational modeling and numerical analysis. The numerical part is focused on the modal analysis of the homogeneous beam sample by finite element method in the ADINA software environment.

Mill-turn center is an advanced CNC machine tool. This paper presents a novel approach to the conceptual design of a mill-turn center. Firstly, the feature model of a mill-turn center is created based on a RW (representative workpiece) in a Top-down way. After that, two concurrent works are studied: the verification model of the machine tool is setup by transforming its finished feature model; the NC programming is done with the help of the technology of CAM (computer-aided manufacturing). Thirdly, the production verifying of the mill-turn center is fulfilled in the NVMS (NC verification manufacturing system). Lastly, the optimum structure dimension of two functional subassemblies and the correct layout of the machine tool can be confirmed with the modification and feedback. This is a universal method and can be used by the designer of CNC machine tool to promote their job target of quality, efficiency and cost.

The use of recycled or remelted alloys is one of the most common ways to reduce production costs. As the number of remelting increases, also chance of the chemical composition and the microstructure alteration is increasing, which has a major impact on the resulting mechanical properties. The microstructure of recycled alloys mostly affects the presence of iron and its negative effect on casting properties. The paper deals with the degree and the way of influence of the remelting on the microstructure of AlSI9Cu3 alloy with increased iron content to 1.4 wt. %. In the work are progressively evaluated changes of microstructures focused on the morphology and shape of the iron phases, dendritic structure change and pore formation due to remelting on AlSI9Cu3 alloy after natural aging and after the heat treatment (T5). The obtained results point to degradation of the microstructure due to multiple remelting with the possibility of partial improvement when applying heat treatment (T5).

Heat transfer evaluation in a plate heat exchanger (PHE) is one of the most common issue which is widely used in many engineering processes. The objective of this paper determine to formulate a global energy balance in a PHE and to study the heat losses, firstly focuses to study the heat transfer in countercurrent and parallel flow and to measure the temperature profile and to determine the number of transfer units (NTU) effectiveness of a plate heat exchanger. An addition to calculate the overall heat transfer coefficient using criteria equations, also focused to draw the temperature profile of the heat exchanger for both configurations countercurrent and parallel flow with temperature on the axial axis and thermocouple position on the horizontal axis. Furthermore discussed the behaior of temperature across the heat exchanger, compare the countercurrent and parallel flow arrangements, cpaing the experimental heat exchanger effectiveness with that estimated by the NTU method, the NTU effectiveness method application in the calculation of the output temperatures of a PHE. This concentric plate heat exchanger allows the study of heat transfer between hot water flowing through an internal sheets and cold water flowing in the ring area lying between the internal and external sheets, the plate heat exchanger allows measuring hot and cold water temperatures in different points of the heat exchanger.

High strength steel 22MnB5 according to DIN EN 10083-3 belongs to the group of HF steels frequently used in the production of coachwork. Using the thermo mechanical pressing can be achieved that these steels have strength of about 1500 MPa. The surface of this steel is provided with a protective coating to protect it from oxidation. Galvanic ally, a Zn-based layer is used to provide cathodic protection. The Zn-based layer is limited by the temperature which is insufficient for TMP. Hot-dip galvanizing is also applied to an Al-based layer that does not serve as a cathodic protection but is used as an effective oxidation barrier. The quality of the Al-Si layer is important with regard to the resulting quality of the formed blank. The properties of the surface Al-Si layer affect not only the conditions for their application to the steel blank but also the external conditions which are determined by the conditions of the thermo-mechanical processing into the shape of the finished product. To assess the properties of this layer, microscopy methods, namely light and electron microscopy, were used. On the basis of analyzes, conclusions were drawn that should lead to securing the Al-Si layer with the required properties.

This research is engaged in monitoring changes in the tribological behaviour of CrCN thin films at room and elevated (300°C) temperatures. The monitored thin films are deposited by cathodic arc deposition of a pure Cr (99.99 %) cathode under an atmosphere of a mixture of CH4 and N2 gasses. Tribological measurements were performed at a load of 10N, a rotational speed of 60 rpm, and a counterpart of ceramic material (Al2O3). The article also describes the evaluation of wear on the studied thin films due to tribological measurement and temperature.

This paper deals with surface integrity after hard milling of bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear. Non homogeneity of cutting force distribution within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that shape as well as structure remarkable non homogeneity should be expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand, the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

An adhesive bonding technology represents a prospective method of diverse materials connecting. Polyurethane (PUR) adhesives namely are used in an area of the adhesive bonding of wood and cellulose - based products. They gradually substitute formaldehyde-based adhesives. A higher reactivity of isocyanates with any compound having moving hydrogen namely, i.e. e.g. water, etc. is a significant disadvantage. An elimination of this negative factor is possible by adding a filler, e.g. PUR recyclate - based. The aim of the research is to determine an adhesive bond strength of the PUR adhesive modified with microparticles of crushed PUR foam (waste from a building - an insulation material). Improving of a tensile lap-shear strength and a material recyclation of the PUR foam are expected aims. Also a reduction of the adhesive price is a secondary output. Results of mechanical tests were supported by conclusions from a scanning electron microscopy (SEM) analysis with an aim to evaluate the interaction between the adhesive and the recycled filler. A diffusion of the adhesive into a wooden surface would occur at the wooden test samples and so mechanical properties of the modified adhesive would not be determined. This reason led to the research on the modification of the PUR adhesives LEAR D4, PP-6a17 and PP-7a within the adhesive bonded metal bond (a structural carbon steel S235J0). The research results proved a positive influence of the modification of the PUR adhesive with the microparticles of the PUR recyclate. The tensile lap-shear strength was increased. Results of SEM analysis proved a good wettability.

The works deals with a study of fillers influence on chosen mechanical properties of polyamide and the given influence was investigated by using of atomic force microscopy (AFM). Atomic force microscope NT-206 in a complex with control and image processing software is intended for measurement and analysis of surface microrelief and submicrorelief, objects of the micrometer and nanometer range with high resolution. Using AFM it is possible to scan spectroscopic curves that show dependence of composite action force of the probe and surface of the sample on distance between them - they are curves of approach /moving off. In presented measurements by using of spectroscopic curves, the homogeneity and ratio of Young's modulus for polyamide samples were evaluated. For each sample, the curve was created by using of five different places - points. We employed the general approximation and Snedonn's formula for analysis of data and calculation of Young's modulus off complete rake curve. The Sneddon's model gives the relationship between load gradient dP/dh and Young's modulus E.

Plasma nitriding is generally used as a final operation to improve wear, corrosion resistance and fatigue limit of machine parts. The corrosion and wear resistance of nitrided steels can be further increased by converse coating. This paper reports the results of corrosion and wear tests of plasma nitrided and duplex treated (plasma nitriding and manganese phosphate coating) 42CrMo4 steel. Plasma nitriding was carried out at 500 °C in different nitriding atmosphere ratio of 3H2:1N2 and 1H2:3N2 [l/h] for 15 hours. Plasma nitrided samples were subsequently manganese phosphated (without lubrication). The experimental samples were exposed to neutral sodium chloride solution, visually and gravimetric evaluated during exposure tests and after removing corrosion products. The wear test "ball on disc" was carried out at temperatures of 21 ºC, 150 ºC, and 300 ºC, under a load of 20 N. The results confirmed the possibility of applying manganese phosphate coating to plasma nitrided steel to enhance its properties. X-ray diffraction phase analysis found the different volumes of ε-Fe2-3N and γ'-Fe4N nitrides in the compound layers and hureaulite Mn5 (PO3 (OH))2 (PO4)2 (H2O)4 in the manganese phosphate coatings. The results were supplemented by metallographical documentation, thickness and microhardness test.

The following article describes the results obtained from the plasma smelting reduction of a particular type of waste - catalyst with a Cu promoter. The catalyst is used for the process of a selective reduction of nitrobenzene (C6H5NO2) to aniline (C6H5NH2). The plasma smelting occurs in a reducing atmosphere. Six samples of the exhausted catalyst with a Cu promoter were used in the smelting process. The chemical composition of the promoter exhibited a presence of a wide range of elements. Fluorspar (fluorite) and calcium oxide (quicklime) were used as the slag-agent for the given testing. Reducing agent was the powdery graphite - waste from the manufacture of the graphite semi-finished product. The results of experiments, carried out at 80 kVA in the plasma reactor, proved that this type of catalyst can be, in fact, disposed of using the plasma technology. Recyclability of the metal contained in this waste is high; Cu ranges around 88%. Moreover, the article describes the chemical analysis of the slag, fly ash and the composition of synthesis gas in all samples of the processed catalyst.

It is well known that the dynamic behaviour of a vehicle is affected by the design parameters of its suspension system, especially by the stiffnesses of the suspension springs, damping coefficients and tire stiffnesses. Another important factor influencing vehicle vibration is kinematic excitation caused by uneven roads. It may significantly affect the comfort of the driver and passengers, safety of the ride and relative displacements between the sprung and unsprung masses. The paper presents mathematical models of both deterministic and random road unevennesses and numerical simulation of vertical dynamics of planar vehicle models with kinematic excitation caused by these road unevennesses. When examining transient phenomena, standardized obstacles according to STN 30 0560, resp. EU Directive 85/3/EW6-III are applied. Random unevennesses can be obtained experimentally, or generated by the Shinozuka method to create the mathematical model of an uneven road with a specified power spectral density. Actual vehicle prototypes need to be tested on test circuits with different surfaces.

This paper deals with non destructive evaluation of components after plasma nitridation via Barkhausen noise techniques. The effect of the different surface state before plasma nitriding is studied via non destructive Barkhausen noise technique as well as the conventional destructive techniques. Turning operation was performed by the use of the inserts of variable flank wear. The results of experiments show that Barkhausen noise emission is a function of tool flank as well as the different regime of heat treatment. The different state of the surface before plasma nitriding results into the different thickness of compound layer. Furthermore, also the underlying diffusion layer state differs.

The paper deals with the influence of molybdenum, zirconia and cobalt on the AlSi10Mg (Cu) alloy microstructure. The work methodology was focused on the analysis of phases morphology for material alloyed with Mo, Zr and Co. Molybdenum in the AlSi10MgCu alloy creates phases with skeletal morphology bounded on iron phases Al(Fe, Mn, Mo)Si. Used heat treatment has softened these phases and is a prerequisite for increasing the strength characteristics and hardness. By alloying the alloy with zirconium to isolate Al3Zr phases, which represent a strong nucleation potential for α-Al. It has been confirmed that Al3Zr particles do not tend to interact with other elements. The results of experiments show that cobalt affects the morphology of iron phases. The findings of this study can provide further insight into the transition metals in Al-Si-Mg-Cu alloys and the potential for developing a new generation of heat-resistant alloys based on Al-Si.

Currently, it is in the power industry exerted the pressure in terms of environmental impact and economics. That means requirements focussed on the development of high efficiency and low emission systems. Both of these requirements leads to the increasing of the thermal efficiency of a power plant and that means also increasing of the working temperatures. In the future, it will be necessary to develop materials that can withstand these demanding conditions and requirements. Strength of steel used at high temperatures is one of the properties which affect the life time of the power equipment. These properties strongly depend on microstructure of material. However, useful initial microstructures are unstable in service conditions. The changes come gradually at temperature-dependent rate through processes of thermal degradation. Many of these processes are caused by changes in the carbide structure of the steels and other phase transformations.This contribution deals with the degradation structures of the steels applied in energetics.

This work is closely connected with the evaluation of the microstructure of the cast iron with the spherical shape of graphite. The given work is mainly focused on mechanical properties, chemical composition and microstructure, which are important to be known as an input parameters for computational modelling and numerical analysis. The external factors, influencing the measure of the mechanical damping, include the measure of the mechanical loading, loading frequency and temperature. These factors have the influence on the process of the mechanical energy distribution in materials. Eigenshapes as well as eifenfreguencies were investigated by modal analysis using finite element method (FEM).

Nowadays, 3D printing of metallic materials is a hot topic in many industrial spheres as it provides a one-step production of very complex parts. The additive principle based on processing of powders or wires in many successive layers minimizes material losses and so production costs. It also ensures great control over built shapes exactly according to computer-designed models. The most available technology is Selective Laser Melting (SLM) that uses a laser beam to selectively melt a metallic powder into the form of a desired product. The Electron Beam Melting (EBM) technology, that is based on a similar principle, is not so widespread, especially in the Czech Republic. Instead of a laser beam, it uses an electron beam. Related to that, EBM is far more energy-efficient and has different process characteristics. In this contribution, on the example of titanium alloy, we show marginal possibilities of this technology in the processing of bulk materials, from porous to highly dense.

A high performance of heat transfer fluid has a great influence on the size, weight and cost of heat transfer systems, therefore a high-performance heat transfer fluid is very important in many industries. Over the last decades nanofluids have been developed. According to many researchers and publications on nanofluids its evident that nanofluids are found to exhibit enhance thermal conductivity. The aim of this experiment was to investigate the change of workpiece temperature during drilling using Jatropha oil with nanoparticle and water with iron nanoparticle as lubricating and cooling fluids. These experiments were carried out with samples of nanofluid with different volume ratio. Samples JN1, JN5 and JN10 of iron nanoparticles in the base Jatropha oil with iron volume fraction 1%, 5% and 10% respectively. Samples WN1, WN5 and WN10 of iron nanoparticles in the base water with iron volume fraction 1%, 5% and 10% respectively. The work arises from the projects which were realized at University J. E. Purkyně, Faculty of Mechanical Engineering, in cooperation with Namibia University of Science and technology, department of Mechanical Engineering.

The combination of steel and aluminum as a constructional material brings many benefits. Steel is characterized by strength and is suitable for components exposed to high stress. Aluminum is light and is suitable for less stressed parts. However, for technical and economic reasons, the arc welding of these materials has not been possible for a long time. The development of the technology that allows welding of steel with aluminum is linked to the requirements of the automotive industry. This is a process known as CMT - Cold Metal Transfer and refers to the low energy transition of the droplet during MIG/MAG welding. In this so-called "welding soldering", the base steel material is not melted, but merely wetted, whereas in the case of aluminum, a melt weld is formed. The advantage of this process is the lower heat input and consequently considerably less heat deformation. This paper deals with the analysis of the welded joint of the DX51D steel sheet with the Aluzinc layer and the AlMg3 alloy sheet made by CMT welding using the digitized inverter welding power from Fronius company. An AlSi5 welding wire of Ø 1.2 mm was chosen as an additive material. The used technology has led to the formation of a weld with a considerable porosity of the weld metal.

Aiming at the problem of product family assembly line (PFAL) evolution balancing, an evolution balancing model for PFAL is established and an improved algorithm based on NSGA_II is also proposed. Firstly, the product family evolution and assembly line characteristics are researched and analyzed in big data environment. Tasks on PFAL are divided into platform and personality tasks, and the stability of assembly tasks is mainly considered especially. In the optimization process, a chromosome encoding based on TOP sorting algorithm is adopted, and a new density selection and decoding algorithm is proposed to make up for the deficiencies in traditional algorithms. Finally, an example of PFAL planning is given to verify the effectiveness and feasibility of the improved NSGA_II.

This article deals with the issue of mathematical calculating the trajectory of the end-effector of an industrial robot in the manufacture of aerospace composites. Robots are used to define the winding orientation of the fibre strands on a non-bearing 3D core. The 3D core is attached to the robot-end-effector and is led through a fibre-processing head according to a suitably defined robot trajectory during winding of the fibre on the core. The quality of the composite depends greatly on the correct winding angles of the fibres on the frame and on the homogeneity of the individual winding layers. The implementation of these two conditions is related to determining the correct trajectory of the industrial robot, which is part of the composite production technology. The numerical modelling of a passage of the on-bearing 3D core through a fibre-processing head is described in the article. Differential evolution algorithm and matrix calculus are applied to the numerical calculation of optimized robot-end-effector trajectory to achieve optimal angles of windings of fibres on the frame. The numerical calculations of the trajectory of the robot-end-effector were used for verified for the calculated trajectory of the robot-end-effector in the real conditions of robotic laboratory of department of machinery construction.

During the material milling an amount of dust which can significantly influence surroundings is generated. Mainly workers are exposed to a dust pollution. The aim of this paper is to present results of a microclimatic research focused on the dust pollution in a workshop during the milling of MDF boards (Medium Density Fibreboards) and Polystyrene workpieces on CNC milling machine. The concentration of air dust was measured by the DustTRAK II Model 8530 aerosol monitor. Using the special impactors the PM1, PM2.5, PM4, PM10 size fractions were also measured. Obtained results of measurements and concentrations of different size of dust particles were analysed. The conclusion of the research is that it is necessary to watch the optimization of the milling process as well as secondary effects of the technological operations and the inner environment of workshops which can be contaminated by dust particles. A natural ventilation of the large space in which the CNC milling machine is installed is not sufficient. A recommendable solution for an improvement of the current situation is the installation of a local exhausting equipment.

Effect of brittle plate-like Al5FeSi iron phases in secondary (scrap-based - recycled) AlZn10Si8Mg cast alloys with different amount of iron (0.150 wt. % and 0.559 wt. %) on microstructure, mechanical properties (UTS, YTS, ductility and Brinell hardness) and fracture surface were studied. Standard, colour and deep etching were utilized for observation and identification of intermetallic phases (in order to reveal the 3D-morphology of the Si-particles and intermetallic phases). X-ray analysis was used for the evaluation of element composition of the specimen. The results show that SDAS factor decreases with increasing the Fe content; the area proportion and the average length of Al5FeSi phases increased; mechanical properties slightly decreased (YTS from 185 MPa to 176 MPa and UTS from 187 MPa to 178 MPa). The fracture surface consists of transcrystalline ductile fracture, in alloy with 0.150 wt. % Fe the transcrytalline ductile fracture is dominant in the eutectic and on the α-matrix and the transcrystalline cleavage fracture was observed not much; in alloy with 0.559 wt. % Fe the transcrystalline cleavage fracture is dominant.

Electrical conductivity depends significantly on a structural state. It can be influenced by chemical composition, content of alloying elements, presence of different types of phases and dislocation substructure as well. Therefore, the relation between electrical conductivity and mechanical properties is very interesting from a material point of view. In combination with structural analyses (metallography, electron microscopy), important information about materials structures and their changes as a function of various factors (deformation, heat treatment) can be obtained. The present paper describes the role of electrical conductivity measurements during an investigation of the effect of technological parameters on the structure and properties of aluminium alloys.

Article focuses on the monitoring of motor wear of vehicles powered by a dual-fuel diesel-vegetable oil system. The introductory part focuses on the use of biofuels for combustion engines and tribotechnical diagnostics for wear testing. Analysis of engine oil samples from vehicles with different fuels is carried out. Fuel is diesel fuel, biodiesel and a two-fuel system with two fuels - rapeseed oil and diesel fuel. The abrasion wear of biodiesel is increased. Wear in dual fuel system is within the standard exchange interval in the zone of emergency wear of metallic particles and carbon. The article evaluates the adjustment of the oil exchange interval to limit negative effects on wear surfaces. Shortening the interval to the optimum level for biodiesel is 1/3, for dual fuel system is 1/2. Vegetable oil in engine oil causes a change in the character of lubrication. Shortening the interval to 1/2 is necessary to minimize negative effects.

Grinding of cermet was studied to determine the impact of the depth of the cut on the grinding process and the final quality of the finished surface. Depth of cut is an important cutting parameter which affects the whole grinding process in terms of grinding stability, cutting forces, vibrations, spindle load, etc. It is also connected with other cutting parameters such as cutting speed and feed rate which should be optimized to ensure the required surface quality in the required process time. The effect of different depths of cuts on the surface quality in terms of roughness was observed during grinding of two types of cermet rods. An IFM G4 optical device was used for monitoring the surface roughness during tests. The progress of the spindle load was monitored on the grinding machine during grinding. This was used for calculating the resulting cutting forces. Experimental grinding was carried out with a diamond grinding wheel which was dressed before each grinding test. The results of this work will be used for better understanding of the process of grinding cermet.

At present, a large spectrum of cutting tools and machines is available. Therefore, cutting of difficult to cut materials seems not to be a problem which could not be solved by an appropriate choice of cutting system. This article deals with wear of cutting tool edges when milling a superalloy Inconel 718 and its direct influence on resulting roughness of a machined surface. Combinations of different cutting speeds and feeds have been performed. A criterion of flank wear amounting to VB=0.7 mm was chosen for machined material Inconel 718 and used cutting materials in combination with cutting conditions. Regarding the exacting character of the test it was necessary to use an as solid as possible machine, that is why a 3-axis CNC milling machine was chosen. All tests were performed with process liquid because of extremely high temperatures which occur.

The paper deals with kinematic analysis and dimensional optimization of a wheel loader mechanism. The kinematic analysis is based on the kinematic constraints of all joints in the mechanism. The objective function expresses the average angular displacement of the loader bucket and the optimization process leads to its minimum value. The wheel loader mechanism contains two hydraulic drives. The first drive is ensuring rotation of the boom (lifting the bucket) and the other rotation of the bucket. Optimization of the geometric dimensions of the wheel loader mechanism links gives their optimum values which ensure lifting the bucket with its negligible angular displacement carried out by just one hydraulic drive for rotation of the boom. The other hydraulic drive ensuring rotation of the bucket is stopped during lifting the bucket. The optimization results confirmed the possibility of lifting the bucket with just one hydraulic drive for rotation of the boom.

Hot dip aluminizing of steel products leads to the contamination of the batch by iron, which could significantly exceed its admissible levels. The re-processing of thus-polluted Al-Si waste by conventional casting technologies requires extensive technological adjustments, which raise the cost. Therefore, powder metallurgy was used to process Al-Si15-Fe7 alloy (in wt. %) to refine the microstructure and improved mechanical properties without further modification of chemical composition. Mechanical machining (MM) followed by spark plasma sintering (SPS) led to strong improvement of ductility, whereas mechanical machining coupled with high-energy ball milling (HEBM) and consolidation by SPS resulted in compressive strength reaching almost 1000 MPa, but with the absence of plastic deformation. In addition, both samples showed no significant change in mechanical properties even after long-term annealing at 400 °C.