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

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Authors: E.Yu. Balalayeva

The article presents the improved design of the elastic element of the slide direction error compensator. The two-layer elastic element consisting of upper and lower elastic plates of variable thickness is placed between supporting surfaces of the slide and the die upper plate. The joint between the upper and lower plates is stepped The rigidity of this compound elastic element is specified so that at the processing load deformation of the elastic element can not exceed 20-25% of its total height. The optimal value of the horizontal displacement of the upper plate necessary to achieve the necessary rigidity of the elastic element is defined in the article. It has been found that the displacement of the upper plate of of two-layer elastic element should be multiple to the height of the press bed deformation at processing loads. Variable thickness of the compound elastic element may also be used to adjust the interdie space. The processing loads range has been widened as well as the application of the compensator for the «press-and-die» system errors. The proposed design of the compensator elastic element is simple and with minimum of expenses, makes it possible to withstand several million compression cycles

6

Authors: I.О. Vakulenko, О.G. Lisnyak, O.М. Perkov, V.G. Efremenko

The effect of shock wave treatment in water on fatigue behavior of heat treated carbon steel is presented in the article. The carbon steel with 0.45 % of carbon was studied. Before being treated with shock wave the specimens were quenched and tempered at 300oC. Cyclic loading on symmetrical bending trials was performed. It was found that the shock wave treatment results inf hardness and fatigue strength of steel increase. The hardness increase derives from the growth of the total number of the crystal lattice defects. The increase of fatigue endurance is attributed to the moment of transition shift from reversible to irreversible damage up to the higher amplitude area accompanied by growth of cycles number before breakage. It is due to the improvement of steel structure resulting from the shock wave processing. It ensues from the mobile dislocations increased amount, which provides, through recombination, the subsequent increase of endurance in cyclic loading. As an additional source of the amount of mobile dislocations increase is the dislocations tear-out from fastening spots as a result of the shock wave treatment

6

Authors: V.О. Maslov, I.O. Berestovoi, G.V. Berestovaya

The problem of raising efficiency of power plants with internal combustion engines has been analyzed in the article. Comparative analysis of internal combustion engines has been carried out. Energy conversion in internal combustion engines is one of the most energy consuming systems. Efficiency increase of this system is considered with due regard to both the design parameters of a diesel engine and its operating conditions, making it possible to work out more reliable and objective methods of minimizing consumption of natural and energy resources in power plants. Comparative analysis of the existing methods of evaluation as well as of internal combustion engines models were performed with due regard to all the limitations. on its basis the principal drawbacks and imitations of those methods as well as types of engines were determined. It has been decided that in spite of plenty of investigations on the internal combustion engines the problem of selecting a proper engine type it has not been solved yet and solved and further investigations are required. A method of specifying an internal combustion engine type on the basis of descriptive forecasting model was suggested. Such models are compiled by processing of statistic investigations results. The main tendency of development be-comes evident, it being the most important result of this investigation and making it possible to increase the efficiency of these processes. The developed method makes it possible to specify internal combustion engines with optimal parameters, taking into account the heat transfer conditions at modernization or repairs of energy transforming objects. Implementation of this method simplifies evaluation and selection of diesel engines at modernization and repairs that results in energy and resources saving and ensures optimal conditions for technological processes

7

Authors: P.S. Kharlashin, S.O. Gerasin

Various kinds of tuyere sinking into liquid have been developed and tested on a converter simulating model, velocity of gas jet penetration into liquid has been defined, the gas jet behavior in liquid homogenious medium has been researched. Experiments have been made on a simulating model of a 250-ton oxygen converter, made in the ratio 1:25 scale. Water is a metal- simulating liquid. Technically pure oxygen is blown. A one-nozzle tuyere has been used in the experiment, a gas jet going out of it interacting with motionless liquid. The blowing conditions having been specified, the behavior of the gas jet was observed, the crater shape was drawn, the penetration depth was defined. Penetrating into the liquid to a maximum depth the gas jet gets reflected and moves in the opposite direction making the liquid within the boundary layer at the interface move after it. Under such circumstances, gas jet and liquid heat and mass transfer takes place at the interphase surface. The research can be used to determine the dependence of liquid cast iron interphase surface with the oxygen jet in a converter on such parameters as the tuyere height above the liquid iron surface and on the oxygen volume speed at blowing. It was stated that changing position of the tuyere ensures uniform distribution of oxygen in the liquid; the gas jet and liquid interaction makes it possible to give better idea of the mass transfer

7

Authors: O.M. Skrebtsov, V.M. Khlestov, O.S. Kachikov, D.N. Protsenko, V.V. Terzi

Austenite to ferrite and pearlite transformation has not been studied enough for low-carbon peritectic steels. Experiments were carried out in the electric arc furnace. Samples of the liquid metal were taken during smelting; three sample at melting, oxidation and reduction as well as one sample from the bucket were taken. The optical binocular microscope Axio Imagez A2m (production of the German company Zeis AG) was used to analyze the samples for the chemical composition of the elements and for the microstructure(ferrite and pearlite amount). It makes it possible to determine ferrite-to-pearlite relation in steel by means of the special program Thixomet Pro. Experimental percentage of ferrite was compared with the equilibrium percentage of ferrite calculated from the carbon content in the sample from the Fe-C phase diagram. It has been found that during charge melting experimental ferrite content is 0,52-1,7 equilibrium ferrite content. During the recovery period the microstructural heterogeneity stabilizes and is equal to 0,91-0,93 equilibrium heterogeneity. This ratio is in good agreement with the data available in literature. The amount of rejected finished metal as function of the tem-perature of the melt at the outlet of the furnace has been determined as well. The amount of rejected steel is minimum if steel is 1,052-1,07 times overheated above the liquidus point which is equal to the temperature of equilibrium microheterogeneity of the molten metal

8

Authors: V.P. Kravchenko

An analysis of the state of slags recycling in foreign countries was carried out. A modern principle was put forward in the article: blast furnace is an apparatus for manufacturing of two basic types of products : cast iron and slag. Granulation, as the primary recycling of slag melt fixes the structure with certain properties at rapid cooling. An analysis of the existing methods of granulation was carried out and factors influencing the quality of granular slag were determined, as well as the ways of obtaining granular slag with the required physical and mechanical characteristics. The main factors of granulated slags quality, employed for manufacturing of binding materials are chemical composition and the structure of fine granulated particles. All wet methods of granulation are characterized by high humidity of granulated slag, its value reaching 24,5%, due to increase in granules’ porosity. Real options for reducing humidity of granulated slag may include: development of the process of granulation, ensuring manufacturing of products with increased density and low content of fine fractions, dehydration of slag in high bunkers and stacks at sufficient soaking time and slag blowdown with a stream moving downwards. Using mechanical granulators and gaseous energy carriers (air) for melt’s dispersion is an efficient way of reducing water consumption for granulation (semi-dry or dry methods of granulation). It also makes it possible to reduce r consumption of water, supplied for granulation from 3,0 to 0,7-1,5m3/min. Application of air blast for melt’s dispersion influences its fractional composition and grain shape in the slag: the content of the fraction less than 1,25mm reduces to 49,1%, as compared to conventional 92,8%. The content of spherical grains is with tough surface is 33%, it promoting reduction of residual humidity of granulated slag. Thus, application of air blast for granulation of slags is an efficient way of obtaining high quality granulated slag

8

Authors: P.S. Kharlashin

A new approach to the assessment of the «critical» concentration of impurities in metallurgical melts has been put forward by the author. The inapplicability of the traditional method of their calculation, based on kinetic studies of oxidation processes for the elements, the affinity with oxygen of which is lower than that of the base metal melt has been shown. The nature of the oxidation process when the impurities concentration is above the critical concentration, has been ascertained, a great number of laboratory and field data having been used. It has been proved experimentally using the developed installations that oxidation of arsenic hardly occurs in real metallurgical melts. There is a concentration gradient as to the mo-lecular and convective diffusion, providing for the transfer of the reacting components in steel tubs. The kinetic equation for the oxidation of impurities at concentrations below the «critical» concentration has been shown. An attempt was made to determine the «critical» concentration of arsenic; arsenic being one of those elements, chemical affinity with oxygen of which is higher than that of iron; it forming volatile oxides. The author managed to show that in case the concentration of arsenic in the melt Fe-As is critical iron becomes the oxidizing component and it is its «critical» concentration that should be determined. Kinetic curves of impurities’ oxidation in «concentration – time» coordinates have been built. The «critical» concentration of solvent metal can always be determined from the beginning of the oxidation process retardation. The data obtained in the refining of arsenic-bearing conversion pig iron at the steel works «Azovstal» have been listed. Critical concentration of arsenic is possible and can only be detected under certain conditions of the oxidating refining, that provides for the transition from the surface of the reaction to gaseous As2О3

9

Authors: V.О. Maslov, L.О. Trofimova, L.О. Dan

Investigation of carbothermic self-recovering kinetics of metallurgical production Fe-C waste materials has been continued in this work for model monodisperse wustite-carbon and magnetite-carbon samples. On the strength of the results of differential thermal analysis the temperature of the beginning of the interaction in polydisperse material was determined. It should be more than 960oC. Kinetic curves of carbothermic self-recovering at 970oC and 1050oC were obtained on monodisperse model samples. During the study of high-temperature processing kinetics of Fe-C waste materials the amount of removed oxygen was determined from the volume and composition of the emitted gas phase. The method comprising simultaneous volume - dynamic and gas analyses was used. Analysis of the results showed that with increase in temperature the maximum rate of oxygen removal was achieved faster and had greater value. Analysis of the gas phase showed that at the initial stage of the process CO content was low over the whole operating temperature range. Then it increased and CO/CO2 ratio remained constant till the experiment was over. The concentration of CO for all temperatures being studied was about 75%, the rest was CO2. It convincingly indicated that the process is out of equilibrium with the gas phase and shifting towards CO2 formation. It was found that the completion of the first stage of the process is characterized by virtually zero magnetic properties of the material, i.e. by obtaining pure wustite. The obtained results confirmed the two-stage scheme of carbothermic process of dispersed Fe-C waste materials self-recovering and its topochemical nature. Studies of electrophysical and magnetic properties of the samples after the carbothermic self-recovering have been made. We found that for the studied materials the value of the specific saturation magnetization keeps growing during the process, reaching 179 Am2/kg for wustite-carbon sample. The obtained value of the specific electric resistance varies slightly from 1,710-4 to 2,710-4 Ohmsm

10

Authors: K.O. Shmeltser, V.P. Lyalyuk, V.P. Sokolova

To study the influence of coal batch properties on coke strength we have considered the quality of the coke produced at the plant in Krivoy Rog from 2008 till 2012. Such factors as the large number of coal suppliers, imprecise selection of the optimal degree of batch crushing result in the decline in coke quality, the batch density and contents of the lean class (<0,5 mm) are not optimum; poor blending of the batch after crushing; increased moisture and ash content of the coking batch; and extreme fluctuation in the coal and batch characteristics. It was found that high humidity of coal batch and its large fluctuations has most profound effect on the mechanical properties of coke. Under deteriorating resource base the quality of the coking batch preparation is important, To have batch of proper quality the following key aspects must be taken into account: the batch must be crushed to an optimum degree that will result in leaning components decrease and increased contents of vitrivite in it which improves the sinterability and coking, and hence the quality of coke; the degree of mixing of the coking batch in all indices must be up to 98-99%, for uneven distribution in the coal chamber worsens the quality of coke

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Authors: P.S. Kharlashin, V.O. Sinelnikov, Assiil Kadhim Mohammed

Guniting and residual slag spraying in an oxygen converter, gas-cooled tuyeres of several patterns have been offered. The calculations to reduce oxygen consumption required for lancing, as well as to simplify the tuyere design have been made. Systems of differential and integral equations have been used to calculate such factors and physical actions as powder concentration, duct length and power influence, suspension of matter in gas velocity relation over the area of high temperatures. Experiments have shown that substitution of the gas-cooled tuyere for the water-cooled tuyere converts the tuyere into a heat exchanger making it possible to use the energy formerly lost as a result of dissipative losses. The results of this work can be used to improve existing and new advanced technologies that reduce emissions into the environment

10

Authors: A.S. Mnyh

Thermal regime of blended materials sintering results from the distribution with height of solid fuel and chemical components in the layer. It depends on the loading mode and fractions segregation across the charge prepared for sintering. Loading in its turn, depends on the loading device, the design of which will influence the forming of the layer of material, and consequently, the fractional composition of separate horizons of the charge stacked on pallets. In the work, a layer of polydisperse charge being loaded onto the pallets of the sinter machine and the layer forming process dynamics have been studied. The way to calculate the fractional composition of the charge distribution with the height of the layer has been put forward by the author and operating range of the tray parameters for the effective work of it has been offered as well. The design of the tray with an air gap and consisting of several parts makes it possible to change the angles of the inclination of the either surface which in its turn influences the rate of the moving particles as well as the width and height of the air gap, thereby providing for the control over the dynamics of the layer formation. Research has led to the conclusion that the use of such a tray is the most effective providing for the desired distribution of the material fractions and consequently for the distribution of solid fuel by horizons of the mixture prepared for sintering, which makes it possible to stabilize the thermal conditions of the sintering process and improve energy efficiency and productivity of the sintering process

11

Authors: F.I. Lukhtura

The influences of regime parameters (total pressure differential, surplus impulse, consumption etc.) on change of the blowing stream characteristics (hitting range of the jet joined to the gas mass jet from the surrounding medium, etc.) in discharge conditions without acoustic feedback through the nozzles with different Mach num-bers, the generatrix and the widening nozzle axis forming an angle have been analyzed. The corresponding dependencies for submerged (isothermal) jets have been received which practically coincide with the experimental data. The regimes undesirable for blowing have been shown. These results and the analyses of the parameters of the supersonic jet as a function of the melting blowing regime refers to the jet penetrating the liquid with the difference that it is necessary to take into account such additional factors as the gas composition and temperature of the gases surrounding the jet, opposite streams of gases, the availability of the second phase, and so on. The received results must be taken into account in designing, improving and operating blowing devices and burners. The received dependences to define the hitting range, additional mass, the jet section diameter on various factors, that is discharge parameters, blowing devices design and others can be used in choosing the peculiarities of the nozzle design in blowing devices and blowing regimes optimization

13

Authors: F.I. Lukhtura

Real parameters of the gas expiring out of narrowing nozzles of different confi-guration have been calculated knowing the discharge coefficients obtained experimentally. Rather a simple method to calculate the «second» critical pressure differential dependent on discharge coefficients at cut-off expiration modes has been offered. Using an inviscid fluid one-dimensional model the author has confirmed that it is impossible to receive critical speeds in the output hole. The method makes it possible to estimate the value of the pressure in the separation point (if it is available), where the Laval nozzle section is minimum and knowing «second» critical pressure differential (or total pressure at cut-off expiration). The received data can be used as initial data to calculate jet flows passing through various kind of holes. The analytical research results of gas discharge regime through the holes (nozzles) have shown, that a one-dimensional model can be used to calculate the parameters of the expiration through holes of different configuration in the nozzle narrowing part precisely enough to estimate changes of the main (basic) flow parameters in the channels of the holes. The analysis of the research indicates that the flow coefficients at flow-off expiration modes for convergent and convergent-divergent holes are identical and the parameters in critical section are identical as well. The total pressure recovery coefficient is approximately equal to the flow coefficient, there being losses of total pressure. The received results can be used in power engineering, metallurgy etc. developing various blowing devices and burners