Dobrany, Czech Republic
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Comtes Fht | Date: 2014-12-30

The gear driven by wobble movement contains an ergonomic pendulum (D), a centric disk (C) and a flywheel (A) which have a common axis (S) of rotation. In the axis (S) of rotation a shaft (H) is placed which is rigidly joined to the pendulum (D). The mutual concentric position of the centric disk (C) and the flywheel (A) is delimitated by one planet disk (B) at least which contacts the outer periphery of the centric disk (C) and the internal periphery of the flywheel (A) and is joined rotatably to the supporting structure (T). The supporting structure (T) is fixed to the linked structure which fixes the supporting structure (T), together with the planet disk (B), against rotation with respect to the axis (S) of rotation. Between the shaft (H) and the flywheel (A) a first freewheel (VI) is situated while between the shaft (H) and the centric disk (C) a second freewheel (V2) is situated. The senses of rotation of the freewheels (VI and V2) are different. The vehicle comprising this gear has a linked structure to which the supporting structure (T) is fastened, having the form of the frame (U). To it the wheel (K) or the pair of wheels (K) are fastened.

Dlouhy J.,Comtes Fht | Motycka P.,Comtes Fht
METAL 2016 - 25th Anniversary International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2016

It is well known, that lamellar pearlite austenitization can lead to rapid spheroidisation of cementite. This phenomenon is the base for ASR process - Accelerated carbide Spheroidisation and Refinement. It is possible to obtain fully spheroidised structure from lamellar pearlite within minutes by partial austenitization and divorced pearlitic transformation. Moreover, such structure is significantly finer than spheroidised structure after conventional soft annealing. The size of carbide particles obtained by ASR process depends on the austenitization rate. This is an important fact, because various kinds of heating methods can be applied for steel heat treatment with heating rate differing by decade orders. This article describes cementite morphology during spheroidisation with respect to the austenitization kinetics. 100CrMnSi6-4 with pearlitic structure was austenitized isothermally at different temperatures and continuously at different heating rate. Cementite lamellae fragmentation at interphase boundary perlite/austenite was examined by SEM after deep etching. Size and distribution of resulting cementite fragments was characterized. Austenitization kinetics was observed via dilatometric measurement.

Slama P.,Comtes Fht | Nachazel J.,Comtes Fht
IOP Conference Series: Materials Science and Engineering | Year: 2017

Aluminium Al-Mg-Si-type alloys (6xxx-series) exhibit good mechanical properties, formability, weldability and good corrosion resistance in various environments. They often find use in automotive industry and other applications. Some alloys, however, particularly those with higher copper levels, show increased susceptibility to intergranular corrosion. Intergranular corrosion (IGC) is typically related to the formation of microgalvanic cells between cathodic, more noble phases and depleted (precipitate-free) zones along grain boundaries. It is encountered mainly in AlMgSi alloys containing Cu, where it is thought to be related to the formation Q-phase precipitates (Al4Mg8Si7Cu2) along grain boundaries. The present paper describes the effects of mechanical working (extrusion, drawing and straightening) and artificial aging on intergranular corrosion in rods of the 6064 alloy. The resistance to intergranular corrosion was mapped using corrosion tests according to EN ISO 11846, method B. Corrosion tests showed dependence of corrosion type on mechanical processing of the material. Intergranular, pitting and transgranular corrosion was observed. Artificial ageing influenced mainly the depth of the corrosion. © Published under licence by IOP Publishing Ltd.

Chvostova E.,Comtes Fht | Dzugan J.,Comtes Fht
IOP Conference Series: Materials Science and Engineering | Year: 2017

Application of the mini samples methods is very common especially for residual service life assessment of the components operating in the energy sector. Residual lifetime of operating device can be evaluated using standard tests, but these usually cannot be performed due to limited material amount that can be extracted from the components. It is possible to use in these cases a semi destructive sampling of materials and testing methods employing miniature specimens. This article deals with comparison of the creep results obtained with the use of on standard test bars and sub sized samples such as Small Punch Test and newly proposed miniature samples that are axially loaded. The experiment was performed on steam line steel CSN 15 128 after operation. Emphasis was put to practical use of the test results and therefore residual life was assessed with the use of standard and new mini specimens. The results obtained for standard and mini samples exhibit very good agreement without necessity of any correlation as in the case of SPT and thus much more straight forward approach can be applied even for "unknown materials". © Published under licence by IOP Publishing Ltd.

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: LCE-17-2015 | Award Amount: 9.63M | Year: 2016

The share of renewable energy is growing rapidly driven by the objective to reduce greenhouse gas emissions. The amount of electric power which can be supplied to the grid depends on the time of the day and weather conditions. A conventional fleet of thermal power plants is required to compensate for these fluctuations before large scale energy storage technologies will be mature and economically viable. All power market projections expect this to be the case for the next 50 years at least. For a strong expansion of renewables, this fleet has to operate flexibly at competitive cost. Current power plants cannot fill this role immediately without impeding their efficiency and engine lifetime through increased wear and damage induced by the higher number of (shorter) operating/loading cycles. New technologies need to be introduced to balance demand peaks with renewable output fluctuations at minimal fuel consumption and emissions without negative effects on cycling operation. The FLEXTURBINE partners have developed a medium to long term technology roadmap addressing future and existing power plants. The FLEXTURBINE project presented hereafter is the first step in such technology roadmap and consists of: (1) new solutions for extended operating ranges to predict and control flutter, (2) improved sealing and bearing designs to increase turbine lifetime and efficiency by reducing degradation/damages, and (3) an improved lifecycle management through better control and prediction of critical parts to improve competitive costs by more flexible service intervals and planned downtime, and by reducing unplanned outages. In all areas, individual technologies will be developed from TRL 3 to TRL 4-6. FLEXTURBINE brings together the main European turbine manufacturers, renowned research institutes and universities. It involves plant and transmission system operators to include user feedback and to prepare the take-up of the FLEXTURBINE technologies in power plants world-wide.

Fumfera J.,Czech Technical University | Prochazka R.,Comtes Fht
EAN 2016 - 54th International Conference on Experimental Stress Analysis | Year: 2016

Specimen design for uniaxial low-cycle fatigue test of 08Ch18N10T austenitic steel under large strain amplitude (up to 3%) loading conditions is presented. Design phase FEM analysis including post-buckling analysis with inclusion of non-linear material plasticity is presented. New axisymmetric specimen design based on meridian section of elliptical shape is introduced. Some details about experimental equipment and experimental results are presented.

Dzugan J.,Comtes Fht | Misek T.,Doosan Škoda Power Co.
Advanced Materials Research | Year: 2012

Increasing demand for reliable design of all kinds of structures requires materials properties evaluated under the conditions as close to real service conditions as possible. Presently resolved project dealing with development of new turbine blades geometry requires better understanding of the material behavior under service conditions. Service conditions of turbine blades are cyclic loading at high temperatures under superheated steam conditions. There are not commercially available testing systems providing such functionality and the system allowing samples loading under considered conditions is to be proposed. The paper deals with development of the testing equipment and testing procedure for high cycle fatigue tests in superheated steam corrosive environment. The system allowing cyclic loading at temperatures up to 650°C under superheated steam conditions was successfully designed, assembled and tested on series of testing samples. © (2012) Trans Tech Publications, Switzerland.

Dlouhy J.,Comtes Fht | Kover M.,Comtes Fht
IOP Conference Series: Materials Science and Engineering | Year: 2015

Tool steels undergo spheroidisation or soft annealing to enhance machinability and cold formability. Conventional soft annealing takes several hours. The final microstructure is composed of globular carbides in a ferritic matrix. We present an alternative process of carbide spheroidisation and steel softening. Accelerated carbide spheroidisation and refinement (ASR) was achieved by induction heating at temperatures close to the A1 temperature. The spheroidised structure was obtained in less than 5 minutes. The carbide particles that formed during the ASR were significantly finer than for the conventional soft annealing. The hardness after ASR was higher than the hardness after soft annealing because of the dispersion strengthening by finer and more densely distributed carbide particles. On the other hand, the fine structure is favourable for hardening. It enables smaller austenite grains and martensite laths to be obtained.

Hodek J.,Comtes Fht
METAL 2014 - 23rd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2014

Induction heating is today wide used technology in industry in huge range of fields. Solution of this process contains both solution of the electromagnetic field and solution of the thermal field. In the past were knowledge and experiences obtained mainly from experiments but at the present time is possible to study induction heating phenomena using modern numerical method especially the finite element method [1]. The numerical solution helps to understand induction heating more complex and points out critical issues. Big advantage is use the numerical solution for induction heating coil design. This approach can avoid of long-lasting and expensive experiments with different variants. This paper deals with FEM simulations of induction heating. There are electromagnetic and thermal field taken into the account. The material properties are obtained on the base of material chemical composition. The numerical model considers thermal dependant material properties. Different coil design is considered and variants are compared.

Hauserova D.,Comtes Fht | Dlouhy J.,Comtes Fht | Novy Z.,Comtes Fht
Materials Science Forum | Year: 2014

Carbide spheroidisation is a significant metallurgical process, which contributes to profound changes in microstructure and mechanical properties. Carbide spheroidising occurs through diffusion, which is a long-term and energy-demanding process. The holding times, sometimes up to tens of hours make soft annealing one of the most expensive heat treatment processes. The process was newly designed at the company COMTES FHT shortens carbide spheroidising several times and therefore delivers considerable time and cost savings. The heat treatment was performed using induction heating. The purpose of this annealing process is to obtain globular carbides uniformly distributed in the matrix and to achieve overall softening. The present paper explores the effect of the newly-designed thermal schedules on the cementite lamellae fragmentation, on the decrease in hardness in bearing steel grade 100CrMnSi6-4 and on processing times. © (2014) Trans Tech Publications, Switzerland.

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