Reporter of the Priazovskyi State Technical University. Section: Technical sciences

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Authors: L.K. Leshchinskiy, V.M. Matvienko, V.O. Mazur

It has been shown that if choosing a metal composition for surfacing rolls and rollers of continuous casting machines, both the carbon impact on the mechanical and functional properties and the critical values of the chromium concentration, which determine the corrosion resistance of the metal with regard to electrochemical corrosion theory, should be considered as well. The paper studied the effect of chromium and carbon steel the X5-X12 type on the structure, technological strength, mechanical properties, fracturing resistance and corrosion resistance of the weld metal. The composition of chromium tool steels (deposited metal) (X5-used for the rolls of hot rolling mills) and (X12-used for continuous casting machines rollers) correspond to these values. The impact of carbon on the properties of the deposited metal containing chromium was considered by comparing the data for both types of the deposited metal. It was found that for both types of the deposited metal (X5 and X12), the limiting value of the carbon content, providing an optimal combination of strength, ductility, failure resistance is the same. If the carbon content is more than the limiting value – (0,25%) the technological strength and failure resistance of the deposited metal significantly reduce. With increasing carbon content from 0,18 to 0,25% the martensite structure has a mixed morphology – lath and plate. The strength and toughness of the deposited metal grow. Of particular interest is simultaneous increase in the specific work of failure resulted from crack inhibition at the boundary with far less solid and more ductile ferrite. As for the 5% chromium metal, the X12 type composition with 0,25% C, is borderline. With a further increase in the carbon content of the metal both ductility and failure resistance sharply decrease and with 0,40% C the growth rate of fatigue crack increases by almost 1,5 times

5

Authors: V.L. Malinov, O.S. Savenko

The induction heating process is put into effect through an inductor with high current flowing in its winding. The part to be heated is placed in the inductor magnetic field and can be represented by an equivalent transformer secondary shorted one-turn winding, the inductor being the primary winding of this transformer. The inductor is often powered by a resonance converter fed from the mains through a rectifier. The rectifier (e.g. six-pulse diode bridge), and the smoothing capacitor at its output results in a distortion of the current consumed from the mains(that is its non-linear harmonic distortion coefficient increase) and in the reduction of the induction heating converter power factor. To reduce non-linear harmonic distortion coefficient of the input current, power supplies are used in conjunction with passive harmonic filters or with parallel active power filters. Due to the introduction of the standards normalizing the emission of high-order harmonic currents by technical means, the task of creating power supplies with high power factor and with minimal distortion of input currents is becoming relevant. The article proposes a circuit solution of power supply for induction heating. The de-signed power supply is powered from a three-phase mains and has a small distortion of the input current wave shape. A characteristic feature of the power supply is the use of direct conversion of a three-phase mains voltage into a high frequency voltage, which is then used for «pumping» the output resonant circuit with the inductor. The power part of the proposed converter consists of six identical semiconductor diode-transistor switches – two per a phase. Converter control system ensures the formation of the mains currents so that they are proportional to the corresponding instantaneous phase voltages. Thus, the designed power supply presents a symmetrical and purely active load in relation to the mains

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Authors: A.V. Belostochnyy, P.V. Soloshenko, M.О. Grigorieva, S.V. Savenkov

Mechanical properties and metal structure of all-metal gas tanks made of medium-carbon steel after different periods of service have been studied. It has been observed that the duration of the service does not significantly influence on the strength of the metal tanks, but it leads to some reduction of plasticity and toughness decrease. It has been observed that toughness degradation appears after 25-30 years of tanks exploitation. At testing of the Menazhe and Sharp specimen it was also found out that temperature dependence of metal tanks toughness varies with the service life. It has been noted that the metal microstructure does not change under continuous operation. Therefore the decrease in properties after long-term use of the cylinders was caused by the metal substructure. Exploration of the mechanism and kinetics of the substructure changes requires special studies. On the strength of these data the need to improve the existing methods of periodic inspection (as a function of service time) of all-metal steel cylinders, as well as set-ting limits of the life-span of these vessels has been shown

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Authors: F.V. Novikov, V.I. Polyanskiy, О.О. Andilakhay

In this paper we propose a new theoretical approach to the calculation of the temperature of the blade cutting tool, taking into account the distribution of heat released during the cutting process, formed between the chip and the surface layer of the workpiece. On the basis of the received analytical dependences for determining the temperature of cutting when turning the basic conditions for its reduction have been defined. They mainly consist in reducing the cutting adequate stress (machining energy consumption) by reducing the intensity of the cutter friction against the cutting material in the cutting zone by applying a high-speed processing, but also by reducing the main cutting edge angle. It has been shown that if the cutting speed and longitudinal feed continuously increase the cutting temperature continuously increases as well, asymptotically approaching a constant value equal to the temperature of the produced chips. This indicates that with increasing speed of cutting and longitudinal feed all the heat generated during cutting is spent on heating the chip, and just a small part of the heat goes into the workpiece. As a result, it is possible to improve the quality of the treated surface as the probability of forming burns, cracks, and other temperature microscopic defects occurring on the treated surface decreases. Calculations revealed that neglecting the heat going into the resulting chips in turning leads to a significant increase in cutting temperature up to the values physically unrealizable in cutting. Consequently, it is possible to calculate maximum cutting temperature close to the experimental values only taking into account the heat balance going into the chips and the surface layer of the workpiece. Practical recommendations for improving blade processing technology based on the reduction of thermal stress in cutting have been given

6

Authors: O.M. Zynovchenko, G.G. Garkusha

Brief analysis of the known teaching methods through the use of computer has been given. Computer-aided teaching system includes an interactive lecture, laboratory works, an application for online testing and evaluation of the new knowledge assimilation and the software used by the teacher. The virtual lecture presents information as sound tracked dynamic pictures accompanied by permanent practical work that fixes the acquired knowledge in the student’s mind. Each teaching step in the virtual lecture is followed with practical work evaluated by the computer. Virtual labs make it possible to consolidate the new knowledge by practice. They provide for the individual activity of the student, monitor his progress and automatically evaluate his knowledge. These applications are installed in the student's computer. The computer applications of the teacher include a generator of the tests for testing and evaluation of the new knowledge, a typical problems base, personal information files generator for each student and a computer application forming the final mark of the student. The results of the testing of this teaching system show that it is efficient, making it possible to organize a flexible schedule of the educational process,cutting down the working hours of the teacher

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Authors: О.M. Skrebtsov, S.L. Makurov, О.S. Kachikov

Possibilities of using X-rays in the study of the structure theory of liquid metal melts and the published data results have been investigated in order to improve this theory. In the theory of liquid metal melts there still remains a lot of subjects under discussions now. For example according to modern concepts of the liquid structure it includes metal clusters and disordered melt zone. Both structures are constantly exchanging atoms. According to expert information, for example, some authors (V.I. Arkharov, B.A. Baum et al.) believe that the overheating of the melt by 100-200 degrees above the liquidus point leads to complete destruction of the cluster. According to others, the destruction of clusters occurs only close to the boiling temperature of the melt. Besides it is not clear whether a cluster is a ball or convex polyhedron? As a result of high-temperature X-ray studies of liquid metals we have found that the genetic structure of a liquid metal depends on the crystal system of solid metal crystals. X-rays interference from the liquid metal clusters may occur when there are two or more rows of vibrating atoms, arranged in parallel planes. Therefore many authors who consider clusters to be spherical are wrong. Apparently a cluster is a parallelogram or a convex polyhedron

7

Authors: A.V. Loza, V.V. Chigarev, V.V. Shishkin

Among the various types of metallurgical equipment there are structures which are welded compounds of a cast base and additional elements produced by casting or any other means. Such structures are called cast-welded constructions. Besides new working properties such constructions appear to be more efficient and provide better durability as compared to the similar structures produced by other industrial means. Meanwhile the advantages of the technology are not used in full. One reason is low quality of the compound products caused by lack of proper preparation of the elements to be welded and poor quality of the welds themselves. In the article the methods of quality production and the maintenance of steel cast-welded constructions have been considered. A ladle of a blast-furnace slag car is used as the subject of investigation and further testing of the mentioned above technologies. The ladle is a cast product. Under operating conditions, the ladle undergoes mechanical and thermal load, which results in deformation of its sides that deflect inside. To prevent the deflection stiffening ribs are welded onto the outer surface of the ladle. However, there may be casting defects in the base metal that could reduce the durability of the welds. It has been proved that welds on the unprepared cast base of the steel product cannot guarantee the combination’s durability and reliability. To prevent the influence of the casting defects it has been recommended to cover the base metal with one more metal layer before welding the elements on. Two-layer surfacing provides best result as the first layer serves for the weld penetration of the casting defects since this layer has a significant share of base metal therefore it is less malleable; the second layer is necessary for making the layer viscous enough. The viscous layer ensures the absence of sharp transition from the deposited metal to the base metal and increases the crack resistance of the weld. In case the recommendations are followed, the high quality of steel cast-welded constructions and their longer service life can be ensured

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Authors: V.V. Kukhar, O.Yu. Nesterov

Some methods of polymeric materials waste recycling have been analyzed in this paper and the prospects of the theory development as well as extrusion technology and co-extruding processes have been shown. The purpose of this work was an analytical research of the backpressure in different sectors of the extruder when the pressed bulk moves through it and improvement of the working conditions of the device to fit the technology of plastics waste processing. The recommendations as to the calculation of the required design parameters of the screw, as the main structural element of the extruder, have been developed as a result of research, which makes it possible to achieve better processing of the pressed bulk under specified temperature and rate conditions due to the levelling of the backpressure and pumping effect in all sections of the device. The proposed upgrading provides productivity levelling in all sections of the extruder, which excludes intermittent work, breaks and thickness unevenness of the manufactured products. Through the analytical consideration of the extrusion process theory in various sectors of the extruder, which are characterized by different temperature conditions and the pumping effect, the equation for calculating of the auger screw inclination angle for each sector of the extruder has been obtained which makes it possible to improve the machine design. The example of the calculation of the screw design parameters for physical and chemical characteristics of low-pressure polyethylene under the conditions of its processing has been furnished

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Authors: V.E. Krivonosov

Reactive power compensation is particularly relevant for the industrial companies, major power consumers of which are asynchronous motors (АM). The most effective reactive power compensation is at placing the capacitor bank (CB) directly at the points of AM connection. The capacity of the CB and the method of controlling the power factor depend on the AM loading conditions. Under operating conditions ensuring AM reliable start-up after a technological pause is an important task. Reliable motor start-up is possible when the insulation resistance of the stator windings is equal to or above 0.5 megohms. The discharge of the capacitor bank at the moment of the AM disconnection from the network, makes it possible to use the power stored in the CB to diagnose insulation condition and suitability of the AM to a safe start. The speed of the CB discharge is the criterion showing that the AM winding insulation resistance is of critical value. The capacitors discharge simulation made it possible to develop a method to protect the AM and the power cable as well as to formulate an algorithm to identify one-, two-, three- and interphase short circuit when operating, and at the time of the AM disconnection from the network and to define the critical value of the insulation resistance according to the capacitor discharge speed

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Authors: O.P. Kirkin, T.Y. Kirkina

Development of information technologies and market requirements in effective control over cargo flows, forces enterprises to look for new ways and methods of automated control over the technological operations. For rail transportation one of the most complicated tasks of automation is the cargo flows distribution over the sites of loading and unloading. In this article the solution with the use of one of the methods of artificial intelligence – a fuzzy inference has been proposed. The analysis of the last publications showed that the fuzzy inference method is effective for the solution of similar tasks, it makes it possible to accumulate experience, it is stable to temporary impacts of the environmental conditions. The existing methods of the cargo flows distribution over the sites of loading and unloading are too simplified and can lead to incorrect decisions. The purpose of the article is to create a distribution model of cargo flows of the enterprises over the sites of loading and unloading, basing on the fuzzy inference method and to automate the control. To achieve the objective a mathematical model of the cargo flows distribution over the sites of loading and unloading has been made using fuzzy logic. The key input parameters of the model are: «number of loading sites», «arrival of the next set of cars», «availability of additional operations». The output parameter is «a variety of set of cars». Application of the fuzzy inference method made it possible to reduce loading time by 15% and to reduce costs for preparatory operations before loading by 20%. Thus this method is an effective means and holds the greatest promise for railway competitiveness increase. Interaction between different types of transportation and their influence on the cargo flows distribution over the sites of loading and unloading hasn’t been considered. These sites may be busy transshipping at that very time which is characteristic of large enterprises. Besides, the question of gaining experience in this model isn't tackled yet and it is to be developed in further publications

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Authors: V.S. Voloshin

The article studies the suppressing of wastes generation at the source of their origin. The comparison of waste generation processes and their energy-entropy balances through an appropriate interpretation of the well-known Prigogine theorem has been done. Waste minimization is just entropy outflow into the external environment in proportion to the inflow of entropy within the system itself. A simplified «Brussela-tor» model for external ultraweak energy impact has been provided. The calculated data of the sequence of space stages of the chemical wave of the initial components distribution in the «Brusselator» like reactions and bifurcation diagram in the processes of self-organization within the production system through an external energy field (ΔE) are presented. It has been shown that when applied to waste generation systems, conventional model of suppressing the waste generation at the source of the origin necessitates providing the optimal parameters for the energy field for each component of the resource base

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Authors: V.S. Voloshin

The article provides an analysis of the state of modern power engineering. The current dependence of the modern civilization on hydrocarbon resources has been presented. The author shows lack of prospects in using hydrocarbon energy sources. The dependence of the stable and non-equilibrium state in various systems of producing useful energy has been stated. The dynamics of growth of CO2 emissions into the atmosphere over the past 35 years and the dynamics of the global consumption of natural energy resources has been shown. Analysis of the technical systems designed for the use of hydrocarbon fuels, exhibited lack of prospects for this branch of industry. The necessity of a radical change in the community as to the energy paradigm has been proved

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Authors: V.G. Efremenko, Yu.G. Chabak, T.V. Pastukhova, V.I. Zurnadzy, V.О. Mazur, О.V. Tsvetkova

The article presents the results of the study of Cr-V spheroidal vanadium carbides cast iron subjected to plasma surface heating. The cast iron contains 3,10% C; 1,05% Si; 3,99% Mn; 9,49% V; 9,10% Cr; 1,71% Ni; Fe being the basic metal. In as-cast state its structure consists of austenite, M7C3- and VC-based eutectics, and spheroidized VC carbides. Plasma treatment was conducted using the plasmatron of indirect action with argon being plasma-making gas. Plasma heating resulted in surface temperature increase up to 1500-1550°С which was followed by partial surface melting, the melted layer being of 160 mm depth. The initial eutectic colonies have become the melted areas; the primary austenite dendrites and spheroidal carbides did not melt. New dispersive eutectic carbides and new primary austenite dendrites developed in the melted layer under superfast crystallization after plasma heating. Thus it was concluded that plasma treatment resulted in modification effect that is a sharp decrease in the size of eutectic colonies, eutectic carbides and austenite dendrites. Subsequent heating in the furnace at 950°C leads to the decomposition of eutectic austenite with the precipitation of the secondary acicular or granular carbides which increases the microhardness of the eutectics by 60 HV as compared with the melted state

10

Authors: O.I. Pronina

Analyzing modern passenger transportation in Ukraine, we can conclude that with the increasing number of urban population the necessity to develop passenger traffic, as well as to improve the quality of transport services is increasing too. The paper examines the three existing models of private passenger transportation (taxi): a model with the use of dispatching service, without dispatching service model and a mixed model. An algorithm of getting an order, processing it, and its implementation according to the given model has been considered. Several arrangements schemes that characterize the operation of the system have been shown in the work as well. The interrelation of the client making an order and the driver who receives the order and executes it has been represented, the server being a connecting link between the customer and the driver and regulating the system as a whole. Business process of private passenger transportation without dispatching service was simulated. Basing on the simulation results it was proposed to supplement the model of private transportation by the making advice system, as well as improving the car selection algorithm. Advice system provides the optimum choice of the car, taking into account a lot of factors. And it will also make it poss-ible to use more efficiently the specific additional services provided by the drivers. Due to the optimization of the order handling process it becomes possible to increase the capacity of the drivers thus increasing their profits. Passenger transportation without the use of dispatching service has some weak points and they were identified. Application of the system will improve transport structure in modern conditions, and improve the transportation basing on modern operating system

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Authors: V.I. Bondar, L.I. Tarasjyk

An array of 177 meltings of the oxygen converter shop of Azovstal plant was formed for the analysis. The dependent variable is the carbon content [C] in the molten metal and independent variables being manganese [Mn], phosphorus [P] and sulphur [S] content, oxygen activity a[o] and the melt temperature (T, ºC). After excluding the variables that do not affect the value of [C], (T, ºC), [Mn] and a[o] were found to be significant. The constructed model [C] = f([Mn], a[o] (T, °C)) is adequate: the value of the Fisher criterion is – 42,06 with the significance level much less than 0,05. The introduction of the additional variable «converter» did not result in a significant improvement of the regression model – the value of the specified regression coefficient increased from 0,41 to 0,45. Histogram of the distribution of the remainders for the obtained model indicate the lack of a normal distribution. Analysis of the data sets separately for the first and second converters has significantly increased the value of the specified regression coefficient up to 0,85 for the first converter, but reduced to 0,20 for the second convertor. In this case the variable (T, ºC) in the regression equation for the second converter turned out to be insignificant. Graphs of the dependence of the remainders for each independent variable on the values of the variable are characterized by a nonlinear trend, indicating lack of normal distribution. Graphical illustrations of the remainders distribution for the first and second converters are alike. However, the correlation coefficient of the remainders and variables values is at the level of 10-7…10-8, indicating the adequacy of the obtained models. Thus, the results of the analysis indicate that kinetic regularities of physico-chemical processes in the first converter are substantially different from the second. The prediction probability values of the variable [C] in accordance with the obtained regression equations confirmed for the first Converter and no for the second

5

Authors: V.A. Lebedev, О.V. Yarovitsyn, S.V. Novykov

A brief analysis of the methods of acicular ferrite formation as the most preferable structural component in the weld metal has been presented. The term «acicular ferrite» is meant as a structure that forms during pearlite and martensite transformation and austenite decomposition. Acicular ferrite is a packet structure consisting of battens of bainitic ferrite, there being no cementite particles inside these battens at all. The chemical elements most effectively influencing on the formation of acicular ferrite have been considered and their combined effect as well. It has been shown in particular, that the most effective chemical element in terms of impact toughness and cost relation is manganese. Besides, the results of multipass surfacing with impulse and constant feed of low-alloy steel wire electrode have been considered. According to these results acicular ferrite forms in both cases. However, at impulse feed of the electrode wire high mechanical properties of surfacing layer were got in the first passes, the form of the acicular ferrite crystallite has been improved and volume shares of polygonal and lamellar ferrite have been reduced. An assumption has been made, according to which acicular ferrite in the surfacing layer may be obtained through superposition of mechanical low-frequency oscillation on the welding torch or on the welding pool instead of periodic thermal effect due to electrode wire periodic feed

6

Authors: V.P. Ruskih, V.P. Kravchenko

Slag wool is the most expensive and valuable product of blast furnace slag processing. Slag wool is in great demand nowadays. The article highlights the factors influencing the mineral wool quality: chemical composition that determines the acidity of the module, the temperature of the molten slag and the required slag jet thickness consistency. Mineral wool is produced by blowing air or steam into a jet of molten slag. As a result of it the slag crushes into droplets stretching. The resulting wool contains 5% slag and 95% air. The quality of the obtained slag wool depends on the module acidity of the slag. The blast furnace slags of «Ilyich iron and steel works of Mariupol» and «Azovstal iron & steel works» are the main (short) slags – they give short fibers. To obtain high-quality long fiber wool it is necessary to add admixtures into basic blast furnace slag to reduce its basicity. As a result of the fuel and energy rising prices and the necessity to reduce the slag wool cost it is necessary to develop a new technology with fiery-liquid slag, with the re-moval of iron compounds and sulphur from the melts and the introduction of corrective additives to improve the quality of slag wool. Good thermal conductivity (about 0,03 kcal/m∙h∙°C) and other indicators (resistance, volume weight) make it possible to use the materials from slag wool (pads, rigid and semi-rigid plates) as heat and sound insulating materials

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Authors: V.О. Maslov, Y.P. Pustovalov, L.О. Trofimova, L.О. Dan

Graphite processing into intercalation compounds followed by thermoshock heating is known in literature. The result is an ultra-light dispersed graphite (thermogra-phenit) used in lots of industries. Graphite intercalation compounds are formed as a result of the introduction of atomic and molecular layers of different chemical particles between the layers of graphite plates. The object of this work is to obtain a new material by intercalation of graphite followed by thermoshock heating, which could be used for products protecting biological and technical facilities from electromagnetic and thermal radiation. In the present work the parameters of oxidation and of graphite thermoshock expansion in order to obtain graphite intercalation compounds and thermographenit were investigated. The experiments were performed under laboratory non-isothermal conditions. Graphite GAK-2 obtained from metallurgical wastes was used. First the fraction of +0,16 mm with the ash content of 0,3% was extracted by scattering. The oxidation of graphite was carried out by potassium bichromate dissolved in concentrated sulphuric acid. The original sample of graphite was mixed with finely grounded potassium bichromate. Then this mass was poured over with 98% concentrated sulphuric acid when being actively stirred and kept. Then the capacitance for oxidation was filled with distilled water. Decantation was carried out until pH=7 in the waste water was got. Separation of the oxidized graphite from the main mass of water was carried out by means of a suction filter until pH=7 was got. Experiments were performed at different ratios of potassium bichromate, sulphuric acid and graphite. The optimum ratio of the components (sulphuric acid) : (dichromate of potash) : (graphite) = 2,8 : 0,15 : 1 was found. The oxidation time was 4–5 minutes. The oxidized graphite turned into thermographenit with bulk density of 2,7–9,5 kg/m3.upon subsequent heating up to 1000oC within the regime of gravity-falling layer. Taking into account the unique structure and low bulk density of thermographenit it can be used as radio shielding, heat insulating, special sealing material

6

Authors: I.O. Berestovoy, G.V. Berestovaya

The article deals with a new approach to evaluation of complex efficiency of diesel engines. Traditionally, cylinder’s capacity, rotation frequency, average efficient pressure inside cylinder, piston’s stroke, average piston’s velocity, fuel specific consumption and other indices are used as generalizing criteria, characterizing diesel engine’s efficiency, but they do not reflect interrelation between engine’s complex efficiency and a set of economic, mass-dimensional, operational and ecological efficiency. The approach applied in the article makes it possible to reveal the existing and modify the existing methods of solving the problem of improving diesel engine’s efficiency with due regard to interrelation of the parameters, cha-racterizing efficiency of their operation. Statistic analyses were carried out, on the basis of which an assumption regarding the existence of interrelation between specific fuel consumption and the analyzed engine’s parameters was made. Processing of statistical data for various analyzed functions of diesel engines helped offer a function, illustrating the link between volume combustion rate, piston’s area and nominal theoretical specific fuel consumption. Interrelation between volume combustion rate, nominal parameters of diesel operation and efficiency indices, obtained by processing statistical data of more than 500 models of diesels of different series was evaluated, the main feature of it being a mathematical trend. The analysis of the obtained function makes it possible to establish an interrelation between economic efficiency of a diesel, its main index being specific fuel consumption and volume combustion rate and design peculiarities

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Authors: E.V. Chuprinov, V.P. Lyalyuk, F.M. Zhuravlev, I.A. Lyakhova, D.A. Kassim

In the course of the laboratory tests, that are close to industrial modes of bowl pelletizers and roasting bowl operations, thermostrengthening modes of raw pellets have been worked out and selected, the main technological feature of the pellets being the presence of rolled up solid fuel. The results, obtained in the tests, showed that the selected modes make it possible to get heat-strengthened pellets with the maximum amount of residual carbon in the final product. The results, demonstrating the effect of the heating rate on the process parameters, in particular, on the content of residual carbon in the obtained heat-strengthened pellets are important. It has been shown that increasing the heating rate of raw pellets from 100 to 500°C/min, and cooling rate of the heat-strengthened pellets from 100 to 600°C/min with decreasing oxygen content in the heat-carrying agent for gas burning in the burners and cooling gas from 21% to 10,3-5,1% make it possible to increase the content of residual carbon in the heat-strengthened pellets from 0,8-1,9% to 3,5-3,7%. The obtained heat-strengthened pellets with the residual carbon not only satisfy all the requirements of the blast furnace melting, but also possess better metallurgical characteristics than oxidized heat-strengthened pellets

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Authors: A.S. Arustamian, A.O. Ishchenko, K. Solek, D. Kalish

Theoretical and practical research of temperature influence on mechanical characteristics of the composite material «Multimetal Stahl 1018» («MM Stahl 1018») have been conducted. Both the laboratory equipment used to measure the mechanical properties, the technique of material preparation and the experimental procedure were described. The compressive tests were carried out on Zwick Roell Amsler HB 100, that can approximate the experiment to real conditions, as it has a special heat chamber in which the samples were heated up to 20°C, 40°C, 60°C and 80°C. The samples were subjected to the load of 15kN, 30KN to complete failure. The experimental values of conventional yield limit of «MM Stahl 1018» samples of various thicknesses for high temperatures have been got. On the strength of this experiment when repairing machinery and parts operating at high temperatures, it is recommended to use the material layer of no more than two millimeters and apply a little loaded nodes. The analysis of the results of the experiments showed that temperature increasing, the yield strength of the material decreases. The «MM Stahl 1018» basing on the best polymers that almost do not shrink at hardening, has good chemical resistance. The powders - fillers include high quality stainless steel, ceramics and additives for improving the surface tension and chemical resistance. Due to its perfect viscous consistency «MM Stahl 1018» can be easily applied with a spatula on wedges breechblocks or bridge supports and is evenly distributed in all directions at assembling. Thanks to «MM Stahl 1018» good forming properties the units may be fitted on the spot with the accuracy of 1/100 mm that is of 100% accuracy, no additional fitting is required, i.e., traditional fitting of wedges breechblocks and piers to the lower zone of the bridge. At assembling a bridge support must be adjusted in the final position with 100% accuracy. This material can work in real conditions at elevated temperatures, but it is still necessary to conduct a series of experiments adding a vibration load as well

7

Authors: O.S. Klenov, F.V. Novikov, V.О Andilahay

The analytical relations that make it possible to determine the components of the cutting forces arising during the turning on the front and rear surfaces of the cutter and take into account the friction and cutting processes have been defined. It has been shown that taking into account the friction of the rear surface of the cutting tool against the material being cut results in the existence of minimum of the radial component of the cutting force as a function of the friction coefficient. In this case the minimum of the radial component of the cutting force is shifted towards the lower values of the friction coefficient with decreasing intensity, and increasing the rake (including both positive and negative values), which is true for both cutting and abrasive treatment. On the basis of analytical relationships cutting and friction energy in the overall energy balance of machining have been evaluated and the conditions to reduce the friction energy have been defined. The reliability of the theoretical solutions has been confirmed experimentally. It has been stated that with the cutting speed increase in turning the tangential and radial components relation increases due to the decrease in the intensity of friction on the rear surface of the cutting tool. As this takes place the angle of action that is equal to the difference of the conventional angle of friction of the material being cut and the front surface of the cutting tool and the rake angle decreases. This shows that the friction coefficient decreases with the increase in cutting speeds due to increasing temperature and cutting power in the overall energy balance of the turning process. Practical recommendations to improve the efficiency of the machining by reducing frictional energy have been made. The technique of computational and experimental determination of the parameters of the power intensity of the cutting process has been offered

7

Authors: G.V. Maslak, G.O. Linnik

The article analyzes the transport service of the cold rolling plant. The additional downtime of the railway carriages in the freight areas and at the station serving the plant has been defined. The factors influencing the process in question have been established. It was found that the loading process itself is carried out according to sophisticated transport technology that provides consistent service of significant amount of the rolling rolls freight areas with powerful locomotives and the supply and cleaning of the railway carriages carried out by small groups as well. It was determined that the share of transport operations is more than 55% of the total time of technological operations in the rolling mills transport and freight complexes. It has been stated that the combined actions of all these factors directly influence on operational indicators in the transport and freight complexes of rolling mills when shipping finished products, the volume of transportation increases and that is manifested as the maximum loading of the station capacities, additional downtime of railway carriages and the use of locomotive time. It has been stated that the proper estimation of transport maintenance of rolling mills becomes an important scientific and technical task. That will make it possible to work out a new approach to increasing the efficiency of transport technologies in transport and freight complexes

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Authors: Yu.G. Chabak, V.I. Fedun, B.V. Efremenko, V.I. Zurnadzhy, A.V. Dzherenova, I.О. Volosenko

The article presents an analysis of the cathode material and the pulse plasma treatment mode influence on the surface microstructure and microhardness of high chrome (15% Cr) cast iron. The methods of metallographic analysis and microhardness measurements were used. It has been shown that pulsed plasma treatment at 4 kV voltage with the use of the electro-axial thermal accelerator results in surface modification with high microhardness 950-1050 HV50, and in the formation of the coating due to the transfer of the electrodes material. The specific features of using different cathode materials have been systematized. It has been found that graphite electrodes are not recommended to be used due to their low strength and fracture under plasma pulses. In case of using tungsten cathode a coating of small thickness (20-30 microns) and having cracks has been formed on the specimen surface. The most expedient is to apply the electrodes with low melting point (such as killed St.3), which provides a high-quality state of treated surface and formation the protective crack-free coating of 80-100 microns thick. It has been found that as a result of the plasma pulsed treatment the enrichment of coating with carbon is likely to occur that results in microhardness increase. The prospects of this technology as well as its shortcomings have been described

8

Authors: V.P. Ivanov, О.D. Razmushlyaev, О.V. Lavrova

Thermal properties of the base metal, shielding medium and the nature of the electrode metal transfer to a great extent determine the penetration area formation in gas-arc welding. It is not always possible to take into account the influence of these factors on penetration front forming within the existing models. The aim of the work was to research the penetration area forming in gas-arc welding. The research of the penetration area forming in gas-arc welding of CrNi austenitic steels was made. The parameters of the regime as well as the kind of the gaseous medium influence on the formation of the penetration zone were studied. The article shows a linear proportional relationship between the electrode feed rate and the size of the base metal plate. The penetration area formation mode for welding in argon and carbon dioxide have been worked out. Diameter, feed rate and the speed of the electrode movement have been chosen as the main input parameters. Multiple regression analysis method was used to make up the modes. The relations of the third order that make it possible to take into account the electrode metal transfer and thermal properties change of the materials to be welded were used. These relationships show quite good agreement with the experimental measurements in the calculation of the fusion zone shape with consumable electrode in argon and carbon dioxide. It was determined that the shape of the melting front curve can be shown as a generalized function in which the front motion parameters depend on feed rate and the diameter of the electrode. Penetration zone growth time is determined by the welding speed and is calculated as a discrete function of the distance from the electrode with the spacing along the movement coordinate. The influence of the mode parameters on the formation of the fusion zone has been investigated and the ways to manage and stabilize the weld pool formation have been identified. The modes can be used to develop effective ways to manage and control the welding process. Making up of the control systems as well as surfacing control involve the selection of the parameters that directly influence the formation of the melting zone as well as the use of these parameters as control signals in real time regime. The influence of the mode parameters on the formation of the fusion zone has been investigated and the ways to manage and stabilize the weld pool formation have been identified. The penetration zone modes formation for the fixed and moving electrodes have been worked out. The relations were calculated through statistical processing of macrosections penetration zones parameters measurement results, the macrosections being obtained by means of arc welding in shielding gases for various diameters of the electrode and various feed rate ranges (current), according to the arc time and its speed of movement

8

Authors: Yu.О. Slobodenyuk, О.V. Byalobrzhesky

At braking the traction motors are transferred to generator mode and produce electrical energy which passes to the contact mains or storage device in the DC mains for further use. Such braking is called regenerative. The resulting electrical energy can be spent by trains in traction mode. Regenerative braking reduces the consumption of electric power for traction. In electric railways of our country more than 3% of the consumed electrical energy is given back to contact mains annually. As this takes place there arises the task to control the braking of the traction motors with minimal impact on electric power quality and maintaining proper braking performance. Based on the analysis of the characteristics of the brake traction of an electric locomotive with asynchronous electric machines the main braking modes have been chosen: at a constant sliding speed and the stator constant voltage; at constant braking power and the stator constant voltage; at a power value more than the nominal braking power; at a constant load torque; at a constant frequency of the stator. The vector control system with the formation of the reactive component of the stator current and the EMF regulator was chosen, basing on the working con-ditions characteristics in the electric braking mode (recuperation); namely, that the characteristics are defined by the laws regulating the frequency and voltage across the stator windings. This control system can fully reproduce any predetermined trajectory of traction and braking performance and adjust braking power. The offered system with recuperation can be used as a means of compensation in emergency situations with a power failure

9

Authors: V.V. Shevchenko

The paper shows that the determination of a failure probability due to the design, technological and operational drawbacks, as well as due to the turbogenerators working time exceeding from statistics data is inaccurate. Machine park of turbogenerators being rather limited in number, the classification and the distribution of generators into groups is random. It can not be used in practice to identify the pre-emergency state of turbogenerators and their timely stop. Analysis and classification of most frequent defects of turbogenerators has been performed. Methods for assessing such defects and reduction of their development have been offered. The article notes that expenses should be taken into account when setting up a monitoring system to assess the state and to identify defects. Reduction of expenditures on both operating and new turbogenerators must be justified. Rapid return of investments must be ensured. The list of additional tests has been proposed: measurement of infrared radiation outside the body of the turbogenerator for the estimation of the thermal field distribution and the defects of gas coolers identification; vibroacoustic inspection of the stator core and casing to find out the defects in the suspension of the core in the stator casing; analysis of the impurities in the cooling gas and in the dry remains of the drainage products to detect the products of the steel core and the winding insulation wear; value measurement and establishment of the partial discharges formation position; research of vibrations to reveal the cracks in the shaft, circuiting in the rotor windings and defects in the bearings. The paper notes that at upgrading as power grows overall and mounting dimensions must be preserved so that the existing foundation could be used as well as the existing security systems. Therefore, when designing or upgrading turbogenerators with an increase in power it is necessary to introduce new design decisions

10

Authors: V.P. Kravchenko

Two types of the systems providing groups of blast-furnaces with blast through one or two common manifolds were analyzed in the article. The first system consists of four turbo-superchargers, working in parallel for one common manifold and four blast furnaces supplied with blast from that manifold. A differential equation was found for such a system, describing pressure alterations inside the manifold, due to parameters of the blast consumed by the furnaces and due to the operation of turbo-superchargers working in parallel for that manifold. The second system of blast supply has the same number of turbo-superchargers and blast-furnaces, but has two common manifolds, connected by a pipeline. A mathematical description of this work as a system of two differential equations, describing the dependence of the blast pressure upon the parameters of turbo-superchargers and the mode of blast-furnaces operation was developed. The obtained differential equations are differential equations with random coefficients. Then it was shown that by replacing these random coefficients with their average values and analyzing the set systems operation mode afterwards it will be possible to evaluate the parameters of the turbo-superchargers, that will make it possible to provide the blast furnaces with blast with preset parameters. Detailed examples were given for each type of the systems, in which the required parameters of the turbo-superchargers were found. It was shown that the second type of blast supply was more preferable, although it re-quires increased parameters of turbo-superchargers

10

Authors: M.V. Pomazkov

A comparative analysis of the known systems of technical reliability of heavy dumpers functionality has been made. It has been stated that the previously proposed methods to determine the optimal service life of heavy-duty dumpers are not effective enough and do not take into account the whole range of factors specific to the operation of heavy dumpers in the current economic realities of industrial enterprises. Based on the analysis results, a mechanism of determining the optimal service life of heavy-duty dumpers and their constituent technical systems ensuring the operational reliability of heavy-duty dumpers has been offered. The article takes into account the analysis of resource factors, general description of system logistic tasks, the main provisions of serviceability, the resource forming in route charts at ore mining and metallurgical enterprises, the use of theoretical developments in practice. Heavy dumpers generalized description modelling shown in the article, the principle of resource use by using interchangable work at different intensity routes has received confirmation in the dumpers’ work schedule

11

Authors: E.V. Parusov, O.B. Sychkov, S.I. Gubenko, L.V. Sahura

Background. Cast metal structure hereditary influence on the properties of finished products is an important issue. To improve the quality of rolled wire it is necessary to obtain continuous casting specimen with the maximum possible length of the zone of equiaxial crystals, dispersed centerline segregation, centerline porosity being welded in the process of hot plastic deformation. Objective. To investigate the continuous casting specimen dendritic structure influence on structure formation in rolled wire associated with the segregation phenomena. Methods. The research was carried out on the industrial continuous casting lots with the initial cross section of 125125 mm from C82D and C86D steels and 11,0 mm in the ready-made diameter. The optical light microscope «Axiovert 200 M MAT» and the binocular microscope «MBI-2» were used. Results. The formation of dendritic structures is most favorable if electromagnetic mixing (EMM) technology is used. In the rolled steel products, made at continuous casting with EMM, there is a tendency to spreading segregation and structural banding, as well as a decrease in the width of martensitic areas. Conclusions. The positive effect of electromagnetic mixing on the reduction in the width of martensitic areas in rolled wire, as well as on the change in the length of the various zones of the dendritic structure in cross-section continuous casting specimen has been established. Segregation increases when the steel is alloyed