Řada strojní. 2011, roč. 57 / Mechanical Series. 2011, vol. 57

Permanent URI for this collectionhttp://hdl.handle.net/10084/111976

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Now showing 1 - 20 out of 57 results

Influence of cutting parameters on heat affected zone after laser cutting
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Zlámal, Tomáš; Petrů, Jana
The contribution deals with method about the thermal cutting of materials specifically with the laser technology. In the theoretical part is described its principle, capabilities and use of the laser in the process of machining mainly procedure of cutting the material using a laser bunch. The experimental part is focused on cutting the cobalt alloy by continuous laser CO2 and the influence of technological parameters during the cutting on final quality of the cutting area. Based on metallographic analysis was determinate suitable technological parameters, have been achieved the lowest heat influence material.
Determination of pump performance using numerical modelling
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Zavadil, Lukáš; Drábková, Sylva
This paper deals with the numerical modelling of the flow in the single-stage centrifugal pump. The main objective is to determine pump performance characteristics using two different geometries – the first one consisting only of the inlet part, impeller and volute, the second one including also the impeller casing, i.e. the gaps on both sides of the impeller. Both stationary and time dependent problems were solved to obtain data for comparison with experimental measurement. The influence of geometry reduction was evaluated and advantages and limitations of both approaches were depicted.
The geometry of pin gearing
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Vávra, Miroslav; Havlík, Jiří
The article deals with creating formulas for calculating geometry of pin gearing when a pin-wheel is replaced by a pin-rack We are interested in creating such equations that are based on knowledge of known parameters given to calculate the geometry of pin gearing, similarly like the involute gearing. Equations of length meshing is also derived from the geometry.
Matlab & Simulink model of rigid rotors
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Tůma, Jiří; Škutová, Jolana
The paper deals with the model of a flexible rotor supported on journal bearings. It is assumed high rotational speed of the rotor and therefore the gyro effects on rotor bearings occur. This model differs from other solutions by the use of complex variables for the planar coordinates. The complex variables simplify mathematical equations and their implementation in MATLAB & Simulink.
Dependence of the digital image of the material texture on the wavelength of the illumination source
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Šuriansky, Jozef; Hrčková, Mária; Krejčí, Lucie
The article deals with methodology of measuring the influence of light source spectre on digital image of material texture. Special original measurement system was used for creating special texture images at various lighting conditions. Structure and principle of functioning of the system are described in the article. In the conclusion a relation between the lighting and wave length on the texture quality is examined using a correlation method.
Changes in biomass energy parameters depending on the harvest season
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Raclavská, Helena; Juchelková, Dagmar; Škrobánková, Hana; Volfová, Martina; Frydrych, Jan
The harvested period of energy grasses can change considerably the problem parameters which influence the process of combustion (concentrations of alkalies, chlorine, nitrogen and ash). The highest losses of water-soluble potassium (> 80 %) were observed for Agrostis gigantea Roth. and Phalaris arundinacea L., the lowest losses were found for Festuca arundinacea Schreb. The losos of water-soluble sodium (36 – 57 %) were Loir than those of potassium. The concentration of chlorine remained almost constant during whole vegetation period.
Proposal 3D assembly process of elevated platforms
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Pavlica, Marek; Petrů, Jana; Čep, Robert
The contribution is dealing with semi-automatic assembly process of elevated platforms. At the beginning of the work dealing with general problems of assembly then focusing on specific assembly. It is also an analysis of the current assembly process. Based on the current process was developed a new proposal assembly. The last step is carried out technical - economic evaluation. That contribution is based on form a completed assembly at company Pars Komponenty s.r.o.
Tracking control system of the modelling yard
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Pavlas, Roman
This article is focused on description of four ways of tracking control on the modelling yard. The yard is situated in the laboratory of Department of control systems and instrumentation. Control system was continuously developed by the help of students. First step was connecting the particular model's objects to input/output devices of the PLC control system and creating the basic programs. Next steps were design and creating of the hand control panel, creating of display views in InTouch software, design and creating of digital control panel and digitalization of locomotives. For every new created hardware and software control components, the program modules were developed (for PLC). The model yard is fully operable at present.
Contribution to turning of alloy on Ni base by ceramic tool
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Mrkvica, Ivan; Konderla, Ryszard
This article deals with dry turning of nickel superalloy - Inconel 718. The different ceramic inserts were applied for cutting process. These inserts were produced by Greenleaf Corporation company. This paper discusses durability of cutting inserts, the different intensity of tool wear at various cutting parameters. The most suitable cutting conditions are chosen in the scope of applied tools.
Optimization of flat forming with the use of draw beads and finite elements method
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Machálek, Jakub; Čada, Radek
Paper concerns shape and properties choice of draw beads in flange area at stamping drawing to achieve stamping dimensions according to drawing. In paper the simulation of stamping drawing process with various variants of draw beads is described together with evaluation of drawing results with the use of analyses of stamping drawability. For calculations and simulations the programmes of AutoForm 4.06 and PAM-STAMP 2G TM using finite elements method were used. The choice of shape and properties of draw beads to be used in serial production is described. In the end of paper the comparison of dimensions of stamping gained by simulations with the dimensions of real stamping which were gained by 3D measurement is carried out.
Experimental analysis of roll bandages for rolling mills
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Macura, Pavel; Fojtík, František; Halama, Radim; Šofer, Michal
The goal of the submitted paper is to introduce briefly results of experimental stress analysis which was focused on bandage of a back-up roll of rolling mill. Measurements have been carried out during technological process of manufacturing particular bandage roll as well as during running in the mill line. At first, residual stresses had been measured from previous heat-treating process and also after following press mounting on the roll. After press mounting a superposition, from the residual stresses and the stresses caused by press mounting, occurred. Stresses from the press mounting have been also numerically analyzed. Manufactured rolls were consecutively built into mill line and after particular time of running, residual stresses on the surface of bandage had been measured. For the purpose of comparison, we have also measured residual stresses on forged roll as well as on cracked bandage of broken out roll. Hole drilling method has been used for residual stress measurement.
Gripper with adjustable grip force
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Lipina, Jan; Tomek, Lukáš; Krys, Václav
The article concerns itself with a gripper, which was made primarily by Rapid Prototyping technology (RP). The gripper has been designed and constructed on the Department of Robotics in the SGS project “GRIPPERS FOR MOBILE ROBOTS” under registration number SP-201071. In the article is documented the robot design particularly in terms of functional parts. An important chapter is a methodology of the gripper testing, where gripper parameters and its functional parts made by the RP technology were verified. In the final chapter are presented conclusions on the utilization of 3D printing for functional prototype components.
Interaction of roundabout and intersection with traffic lights with use of video analysis of conflict situations
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Křivda, Vladislav
The paper deals with problem of interaction of two nearby intersections (roundabout and signalized). The paper presents results of video analysis of conflict situations and design of modification with use of simulation in PTV VISSIM. This paper was prepared with financial support for research and development project No. CG911-008-910 "Influence of structural elements geometry on safety and fluency of operation on roundabouts and possibility of rise crashes prediction”, the Ministry of Transport.
Thermodynamic analysis of a gas turbine cycle fed by different fuels
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Kozaczka, Jarosław; Kolat, Pavel
The paper presents thermodynamic analysis of typical fuels in a theoretical gas turbine cycle. The fuels are burned at different temperatures and different working pressures. In a gas turbine system there are processes of air (and of gaseous fuel) compression, flue gas expansion and heat regeneration. They all run perfectly in the presented theoretical experiment. It means that the pressure changing processes work at the polytropic efficiency equals to one, the process intensities of combustion (as a chemical reaction) and heat exchange are set to one (i.e. the equilibrium is assumed), either. Presented results show that there is useful to distinguish between thermodynamic and the technological values of fuels.
Determining start parameters for oxygen–water steam gasification with and without recirculation
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Kozaczka, Jarosław; Kolat, Pavel
The analytical, unified selection method of the converting medium composition is presented as to apply for the oxygen – water steam gasification the recirculation of reaction products. The selected molar fractions of the converting medium components should give the assumed (needed) CO/H2–ratio of the synthetic gas by the chosen process pressure and temperature. The graphical selection methods applying the MOLLIER–HOFFMANN diagram are used for the parameters preselecting of the air – water steam gasification, e.g. if there is any contents of nitrogen from the atmosphere. The presented analytical method refers to the oxygen – water steam without and with gas recirculation. The last assumption allows the presence of CO, H2, CO2 and CH4 in the converting medium — new gasifying technologies need the permanent presence of carbon monoxide and hydrogen because of the iron catalyst. The determined values of its molar fractions help to choose the suitable process calculation iterative method.
Synchronous measurement of acceleration by MEMs sensors over CAN bus
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Juránek, Martin; Kulhánek, Jiří
This paper discusses possibility of synchronous measurements of acceleration by digital MEMs sensors with the use of the CAN bus. The CAN bus is not commonly used for the synchronous operations, so the main topic of the paper is focused at measurement of the reliability and accuracy of the whole measurement chain on a laboratory stand. We verified by measurements, that digital MEMs sensors can be synchronized over the CAN bus, with respect to theirs typical scanning frequency.
Numerical simulations of steady-state of two-crack rotor system supported by radial active magnetic bearings
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Ferfecki, Petr; František, Ondřej; Rao, Pankaj; Shah, Hardik
The steady-state response of a two-crack rotor system is investigated by computational simulations in the paper. The rotor system supported by radial active magnetic bearings is excited by centrifugal forces of discs unbalances. A flexibility matrix of Bernoulli beam element takes into account coupling phenomena between directions of vibration. The phenomenon occurs in cracked rotors. The couplings express relations between vibration in different directions, i.e. bending-torsion, bending-longitudinal, and torsion-longitudinal. The flexibility matrix elements of the cracked rotor are derived using the concepts of fracture mechanics for transverse surface crack. Partial opening/closing of cracks implemented in motion equations is determined by sign of stress intensity factor for mode I. The factor is computed for the crack edge. The motion equations are nonlinear because the system response depends on breathing of cracks and nonlinear force coupling is introduced by radial active magnetic bearings. Parametric studies of the system response were carried out in order to examine influence of various angles between two cracks. Several recommendations for detection of cracks and monitoring of the cracked rotor are suggested.
Application of robust control algorithms in vector oriented control of induction motor
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Duda, Tomáš; Víteček, Antonín
The paper describes the design of robust control algorithms for the vector oriented control of an induction motor using the state variable aggregation method. The advantage of these control algorithms is their high robustness and simplicity. The control algorithms were designed for the MIMO (three-input/three-output) non-linear mathematical model of an induction motor in an orthogonal coordinate system synchronously rotating with a reference frame. The designed control algorithms were verified by computer simulation in the program MATLAB – Simulink.
Modelling of E2/E2/1/m queueing system subject to breakdowns and customer rejection during failure
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Dorda, Michal
The paper deals with modelling of a finite single-server queueing system with a server subject to breakdowns. Customer interarrival times and customer service times follow the Erlang distribution defined by the shape parameter k=2 and the scale parameter 2λ or 2μ respectively. It is considered that server failures can occur when the server is either idle or busy – operate-independent failures. Further it is assumed that the system empties when the server is broken (all customers are being rejected). Random variables relevant to server failures and repairs are exponentially distributed. In the paper the state transition diagram is shown, the system of linear equations describing the system in the steady state and the formulas for several performance measures computation are presented. At the end of the paper there are shown some graphical dependencies.
Tuning of intricate shape stamping shape and dimensions with the use of drawing process simulations
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Čada, Radek; Tiller, Petr
The paper deals with the process of creation of model of intricate shape stamping from thin sheet-metal – internal reinforcement of car bodyshell B-pillar for flat forming simulations and subsequently with the procedure of its critical dimensions tuning in order to keep the dimensions and tolerances of stamping after drawing process which are given in production drawing. The dimensions of stamping after drawing were evaluated by simulations of drawing process in CAE software Dynaform 5.7 which uses finite elements method. At this software the results of drawing process simulation achieved in comparison with the real process satisfactory results. In the paper the simulation of drawing process of car bodyshell B-pillar stamping is described, the procedure of transformation of given model in digital form and evaluation of drawing results by Dynaform 5.7 software. Also the procedure of the real stamping proportions evaluation compared with the simulated drawing process with the use of CAD software and reciprocal transfer of datas between them. In the end of the paper the procedure of stamping dimensions tuning by corrections of drawing tool parts for fulfilment of all tolerances which are specified in the product drawing is described.

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