Technological machines and equipment used in the food, chemical and other industries, are produced in relatively small batches.  These machines and equipment contains a large number of sheet metal  parts of complex shape having a relatively small height. Traditional methods of stamping are not sufficiently effective for the production  of such parts in small batch production. For the efficient production  of such parts there is a new method for sheet metal forming – forming  gas backpressure. The essence of this method lies in the fact that the  unilateral influence of the hot gas sheet billet is heated to a predetermined temperature, and then is formed. Thus to limit the deformation  of the billet during its heating on the opposite side it creates pressure  the influence of compressed air. As the hot gas a combustion gas-air  mixtures is used. Due to the heating of the billet up to the temperature  range of the warm hot treatment this method provides obtaining of  complex-shaped parts in one work step, which significantly reduces  the cost of production. Studying the heating process of the billet set  up, the pattern of temperature change in time was determined, which  ensures the controllability of the process. The expressions for determining the gas pressure were derived, ensuring the implementation of  the molding process. To implement this method of molding installation for a gas forming a pressure is designed and developed containing device for forming the gas and fuel delivery and control. Using it  the experimental studies were made for the process of forming several  types of components: spherical bottoms, cylindrical part with a flange  part with a surface of double curvature, parts with small relief panels  of the heat exchanger with a helical channel. At the same time, optimal technologi cal regimes of gas molding are determined, ensuring  the obtaining of good quality parts. Experimental studies have shown  that this method of forming allows to obtain parts of complex shape in  one work step using a relatively simple stereotyped equipment. Due to  this application of the molding method can provide considerable cost  savings in parts production, especially in small-scale production. This  method is useful for forming steel parts with thickness up to 1.5  mm  and of parts made of nonferrous alloys with the thickness up to of  2  –  3  mm.

 

When heating billets in a furnace for heat treatment and metal forming, it should be possible to quickly heat the surface of the billet with a minimum differential temperature in its cross-section, which depends on the initial temperature of the surface and the center of the billet, the initial furnace temperature and the speed of its increasing. The temperature difference over the cross section of the billet contributes to thermal stresses in it. In the process of billets heating, thermal stresses must not exceed allowable stress values in the elastic region, depending on the thickness of the heated layer of metal and its chemical composition. Thus, to obtain high-quality billets at a maximum furnace performance, it is necessary to use the optimal heating mode, the testing of which to avoid high material costs can be realized by using physical modeling. Physical modeling of the object of study  – real sample is replaced by a model where the heating is carried out in a furnace model. For physical modeling, one need to choose material of the model, to select or manufacture the furnace model, to calculate the linear scale of the model and to make it possible to calculate the temperature and time scales of modeling, according to which to make model heating at model furnace with the measurement of the temperature field of the model with a further recalculation of the temperature on a real sample. The calculating method is proposed for the temperature field in an industrial billet of ShKh15 steel heated for heat treatment, namely for softening annealing, in an electric well, using physical modeling, conducted in a laboratory chamber electric furnace. The article justifies the choice of material for making the model, and the method of calculation linear, temperature and time scale of the simulation. Based on the experimental measurements of the temperature on the surface and in the center of the model when it is heated in an electric chamber furnace model, the recalculations are given for the temperature field over the cross section of the industrial bloom in different time periods using the received scale.

Now, at emergence of need for rolling of a more difficult bar profile, than standard, development of new rolls design is, substantially, the unformalized procedure. At the same time rather often questions of any optimality of new design aren’t considered at all, being limited to her technical rationality, or are postponed for the second stage – improvement of design in the course of profile production. It is shown that bar rolls design considered as the variable system of calibers, completely corresponds to all signs of the standard concept of the “system”. Therefore, it can be used as the object subjected to optimization with the use of standard methods and procedures of the theory of systems. Calibration of rolls is considered as technological system, and applying the modern ideology of system approach to her description, the universal optimizing model was constructed, directed to design the optimum calibrations applied at rolling any high-quality profiles. The model of the two-stage solution of an optimizing problem of calibration design is applied and it allows using one or two criteria of optimality at different stages of the solution. The generalized algorithm is presented for the solution of an optimizing problem of calibration design of any complexity. According to the accepted concept, at the first design stage the choice of the optimum design scheme is made for specific conditions of the rolling mill, and at the second stage, for the chosen scheme the optimum mode of sinking is generated and the sizes of the used calibers are defined. For implementation of the offered concept and its description, along with the standard terms and formulations, a number of the concepts which don’t have wide use in the theory of rolling are entered. The similar concepts and formulations known from the theory of systems, the theory of optimum control, physics and mathematics are taken for a basis of formation and formulation of such concepts. In particular, such concepts as “Space of calibers”, “Generalized caliber”, “Space of calibrations”, “Efficiency indicators”, “Generating calibration function”, “Space of the sinking modes “, “Generating function of the sinking modes” and others are entered. The essence of these new concepts was stated. More detailed description of separate blocks of optimizing model will be presented in the subsequent articles.

When an external vertical magnetic field is applied to a current-carrying melt in the bath of a DC arc furnace, volumetric electromagnetic forces arise that drive it. Flows of metal and slag occur in the bath of the DC arc furnace. This can lead to their efficient mixing, but can also carry negative aspects,for example, associated with an increase in wear oflining in the region of the bottom electrode. The processes of conductive mixing in the bath of the DC arc furnace during smelting of metals and alloys remain poorly understood, there arise both theoretical questions related to the nature of the flows in the bath under the action of external and intrinsic magnetic fields of a given intensity, and practical with the absence of simple and reliable sources of external magnetic fields. The purpose of this paper isto qualitatively test the capabilities of a physical "transparent" model, to study the nature of currents of a current-carrying liquid under the action of an external vertical magnetic field, and to analyze the possibility of transferring simulation results to processes occurring in a five-ton bath of an industrial DC arc furnace. The principal possibility of studying the current flow behavior of a current-carrying melt under the influence of external magnetic fields on models using non-metallic electrically conducting transparent liquids is shown. In this work the authors have used a water solution of table salt, it allowed to estimate the velocity of the liquid on itsfree surface and near the bottom electrode using video. The physical modeling of the effect of an external vertical magnetic field on the current flowing current in a bath was carried out for different combinations of connecting the bottom electrode and different currents flowing through the bath. The current flowing current in the bath under the influence of an external vertical magnetic field was established when the central electrode or the bottom electrode is displaced from the axis of the bath. It was revealed that when the axis of the bottom electrode is displaced from the bath axis, the average rotation speed of the liquid in the horizontal plane increases. An estimate of the value of the vertical magnetic field strength (about 5  kA/m) is obtained, which should be accompanied by conductive mixing the metal bath of the five-ton steel-smelting arc furnace.

The article dwells on development and practical approbation of the new efficient method of sheet-metal forming providing the controlled heating of billet to assigned temperature and further deformation. Through the heating of a billet to temperature range of hot-cold work and hot working this method ensures producing of complex-shaped parts for one manufacturing operation. There is the description of the construction and performance of equipment designed and developed to accomplish the given method of stamping. Results of the experimental investigation of this method as well as process duties of sample parts making and dependences for calculating the parameters of stamping process are presented in the article

Harmful working conditions entail a consistently high level of occupational and production-related morbidity. In work with the help of correlation-regression analysis, the relationships between working conditions and the incidence rate for the personnel of the blast furnace shop of the metallurgical plant were studied and the assessment of the influence of production factor of chemical nature on the level of occupational risk was made. The staff of the blast-furnace shop operates a whole range of harmful factors, which individually cannot exceed normative values, but in combination with each other can lead to unfavorable conditions. Therefore, it is necessary to be able to assess the effect of a multitude of harmful factors on the morbidity and health of personnel. Based on the analysis of the working conditions of the blast furnace, a correlation-regression analysis of morbidity was performed depending on the characteristics of working conditions. This technique allows to convert the qualitative assessment of the combined effect into quantitative. In the work two methods for definition of professional risk of the personnel are used: standard (on the directing document 2.2.1766-03) and method of an integral estimation of working conditions taking into account combined action of a complex of harmful production factors. According to the results of the study, it can be concluded that the application of a technique that takes into account the combined effect of harmful production factors allows to assess more reliably (in comparison with the standard methodology) the level of occupational risks and the necessary management decisions to reduce it and to improve the working conditions. A  comparative analysis of the incidence of morbidity from harmful production factors with regard to the chemical factor and without it was carried out. Based on the data of correlation-regression analysis, it is proved that the chemical factor have a direct impact on the level of production-related morbidity.The conducted study confirms that a quantitative assessment of the contribution of a certain harmful production factor to a particular type of disease makes it possible to identify trends in improving the working conditions and reducing the risk of occupational and production-related morbidity at mining and metallurgical complex enterprises.

Conducted physical modeling of the influence of an external magnetic field in the vertical bath DC arc furnace for different combinations of connecting the bottom electrode and the different currents flowing through the bath. Determines the nature of the flow of current-carrying liquid in the bath a DC arc furnace by an external vertical magnetic field when connecting a central or offset from the axis of the tub bottom electrode on the "cold" model. It was found that flow pattern current-carrying fluid in the bath DC arc furnace depends on the action of external vertical magnetic fields to the when the bottom electrode the same axis or is offset from the axis of the bath at a "cold" model. Showed that it is possible to explore flow pattern of current-carrying melt, which are dependent on external magnetic fields on models using non-metallic electrically conductive transparent liquids. It was found that the displacement of the bottom electrode axis from the axis of the bath liquid increases the average speed of rotation in the horizontal plane. It was found the order of the vertical intensity of the magnetic field to the for conductive stirring bath DC arc furnace of small capacity.

Thermodynamic analysis of oxygen solutions in carbon-containing Fe – Co melts has been carried out. The equilibrium constants of interaction of carbon and oxygen, the activity coefficients at infinite dilution, and the interaction parameters for melts of different composition at 1873 K were determined. The dependences of the oxygen solubility on the contents of cobalt and carbon in the studied melts were calculated. Carbon has a high affinity for oxygen in iron-cobalt melts. Deoxidation ability of carbon increases significantly with the increasing of cobalt content in the melt. Deoxidation ability of carbon in pure cobalt more than an order of magnitude higher than that in pure iron. Reaction products of carbon deoxidation are gaseous oxides  – monoxide (CO) and carbon dioxide (CO₂ ). The interaction reaction of carbon and oxygen dissolved in the melt, and hence deoxidation ability of carbon depends on the total pressure of the gaseous phase above the melt. Deoxidation ability of carbon increases significantly with the gaseous phase pressure lowering. The minimum oxygen concentration achieved for alloys of the same composition decreased practically an order of magnitude at decrease 10  times the total pressure of the gaseous phase. The gaseous phase composition above Fe – Co melts and equilibrium carbon and oxygen concentrations in the melt at a total pressure of the gaseous phase P, of 1.0; 0.1 and 0.01  atm were calculated. Optimum oxygen concentration (1  –  10  ppm) in Fe – Co melts, depending on the total pressure of the gaseous phase (0.01  –  1  atm) is achieved at carbon contents from 0.01 to 1  %. The curves of the oxygen solubility in carbon-containing iron-cobalt melts pass through a minimum, which shifts toward lower carbon contents with increasing cobalt content in the melt. Further carbon additions leads to an increase in the oxygen concentration of the melt so that the higher cobalt content of the melt, the steeper the increase in the oxygen content after the minimum as carbon is added to the melt.

 

The processes of formation of the skull and liquid film between the mold and surface of the billet effect on quality indicators and stability of the continuous casting of steel. A number of theoretical studies devoted to the forecast of skull thickness and the film of liquid slag are known. However, these studies do not take into account the mutual influence of formation processes of skull and film, as well as formation of shell thickness of the billet. In this connection, the paper presents a mathematical model of interrelated thermal processes developed by the authors in the system of layers “copper wall of crystallizer  – skull  – film of liquid slag – crust of ingot”. The model makes it possible to predict the dynamics of formation of the thickness of the ingot crust, slag skull and the layer of liquid slag along the height of the mold and the length of liquid friction portion in it, depending on casting speed, temperature of casting steel and melting of the slag, thickness of the slab and working layer of the copper wall. The adequacy of the model to the object is determined by such parameters, as surface temperature of the billet, thickness of the crust, specific heat flux in the mold and temperature of the working wall. An example of application of the developed model is shown, in which the effect of casting speed on length of the liquid friction portion in the mold is investigated. It was found that at speeds of 0.8; 1.0 and 1.2  m/min the slag layer is retained for 0.331; 0.415 and 0.498  m from the meniscus of the metal, respectively. At the same time, the thickness of the skull reaches a maximum value of 0.77  mm. Further formation of the preform occurs in the absence of lubrication in the mold. The possibility of using the developed model by technologists for selecting the chemical composition of casting powder, which provides the required length of the liquid slag section, is indicated by the designers when choosing the mold profile, taking into account the thickness of the skull, and, also for educational purposes.