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No 3 (2021)
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https://doi.org/10.21122/1683-6065-2021-3

Anniversary

Metallurgy

29-34 370
Abstract

The article examines the breaks of thin brass‑plated wire for metal cord and high‑pressure hoses of the “sparking” type and the causes of their formation. The wire was manufactured in OJSC “BSW” – he Management Company of the Holding” BMC “ in the conditions of steel‑wire workshops. The appearance and microstructure of breaks of thin brassplated wire of the “sparking” type are investigated. As a result of the analysis of the appearance and microstructure of the breaks, it was assumed that surface defects are formed on the brass‑plated wire – billet during the welding connection in the jaws of the welding machine during annealing. To confi m this, experiments were carried out with the implementation of welded joints of brass – plated wire‑blanks in wet drawing areas, the appearance and microstructure of the obtained samples of welded joints were studied.

As a result of experiments and metallographic studies, the assumption was confirmed that local defects such as “cauterization from sparking” on the surface of the workpiece wire are formed during welding during the annealing operation, it was established that the cause is a violation of contact between the wire and the pressure jaws of the welding machine, wear of the pressure jaws. Photos of the defect, a description of its appearance and microstructure are given.

Based on the obtained studies, a number of measures were carried out aimed at eliminating the causes of this defect.

35-39 612
Abstract

Establishing the true causes of defects is one of the main prerequisites for improving the quality of metal products. One of the undesirable phenomena in the production of continuously cast billets, hot‑rolled products is the oxidation of hot metal in the environment with the formation of scale on its surface. Defects, which are violations of the continuity of the metal and deviations from the normal specified macro‑and microstructure, signifi antly reduce the technological plasticity of the metal in the conditions of its processing and operational stability.

After hot rolling of a circle of 95 mm steel grade 30MpV4, surface defects were found in the finishing line. To study and establish the nature of surface defects from hot‑rolled blanks, as well as continuously cast blanks, samples were taken.

Analyzing metallographic studies of defects and the production technology of the studied steel grade 30MnB4, it was found that the defects were formed as a result of mechanical damage to the continuously cast billet in the area of the pulling‑correct unit. The reason for the formation of the defect is the ingress of scale on the guide rollers.

40-45 374
Abstract

Quality is the degree to which the totality of an object’s inherent characteristics meets the requirements. The product quality control system is a set of interrelated objects and subjects of control, the types, methods and means used to assess the quality of products. An effective control system allows you to make a timely impact on the level of product quality, prevent possible inconsistencies, and ensure their prompt detection at the lowest cost. One of the progressive methods in modern management is the statistical method.

The article considers the program element for quality control in OJSC “BSW – Management Company of the Holding “BMC”. This program element is aimed at working with all types of nonconforming products of the enterprise, at finding the root cause and statistical analysis for these reasons.

46-49 310
Abstract

In order to reduce the cost of producing metal cord in the hardware shops of OJSC “BSW” – the Management Company of the Holding “BMC”, work is underway to modernize and select materials for replaceable technological equipment. In the process of twisting the metal cord on the unwinding of the power coils of rope machines, brake devices are used, consisting of a disk and sectors (pads) fixed in a chain. The elements of the unwinding unit are in constant contact, providing the necessary tension force for unwinding a thin wire. The performance of the braking devices affects the manufacturability of the twist, the absence of breaks, the density and geometric arrangement of the wires in the twisted metal cord that meets the requirements of consumers.

Due to constant contact friction at high linear speeds, the brake pads wear out, which leads to emergency operation of the equipment. The article considers the test results of the modified thin wire unwinding unit and the impact of modernization on the service life of brake pads.

50-54 1884
Abstract

Precision control of hydraulic equipment is a distinctive feature of modern hydraulic systems. With the help of special diagnostic devices, it is possible to reliably and simply monitor the operation of hydraulic equipment. Diagnostic methods can be very different. The article lists the stages and methods of checking hydraulic equipment malfunctions, as well as describes the principles of operation of diagnostic devices of well‑known world manufacturers HYDAC, MOOG, used in OJSC “BSW – Management Company of the Holding “BMC”. Schematically, the connection of the MOOG tester to the production equipment is presented when checking the servo valve in autonomous and combined mode, without resorting to dismantling the valve. Continuous monitoring of the oil purity with the help of the HYDAC FCU device allowed saving time on assessing its condition and taking fast‑acting corrective measures to clean the oil from contamination.

55-60 435
Abstract

OJSC “BSW – Management Company of the Holding “BMC” produces a wide range of carbon, high‑quality, alloyed and high‑carbon steel grades, among which a signifi ant share is peritectic grade steels. Basically, the steel of this group is used to produce rolled products intended for the manufacture of components for the automotive industry. The process of production and casting of these steels is characterized by the greatest instability and is often accompanied by rejects and forced sorting of products. This situation is typical for other metallurgical enterprises. Therefore, the search for technological solutions that ensure an increase in the yield while maintaining the existing productivity of metallurgical units is an urgent aspect of improving the technology of continuous casting of peritectic grade steels. At the same time, the main scientific and technical task is to obtain a stable quality of continuously cast billets, aimed at preventing and eliminating the formation of a number of characteristic defects, primarily cracks on the surface of continuously cast billets and rolled products. The search for methods and technological solutions to improve the quality of products made of peritectic grade steel is the goal of the ongoing research.

61-64 387
Abstract

The author proposed an indicator of the deformation capacity of carbon steel wire rod, which took into account the tendency of the metal to hardening and the general level of plastic properties, and determined technological approaches to the designation of the optimal total reduction before intermediate heat treatment by drawing low carbon wire rod and wire rod for metal cord.

65-73 418
Abstract

The actual problem of obtaining long products from bearing steel grades with specified microstructure characteristics is considered. The analysis of the capabilities of the existing equipment – a heating furnace and a rolling mill 370/150 of OJSC “BSW – Management Company of the Holding “BMC” was carried out in order to introduce technical measures aimed at reducing carbide heterogeneity in products made of bearing steel grades on the example of steel grade 100Cr6.

The influence of different modes of preliminary thermal preparation of continuously cast billets from bearing steel grades on the carbide inhomogeneity in the finished rolling is studied. According to the results of the research, the optimal mode of heat treatment of a continuously cast billet was determined, which allows to produce rolled products that meet the highest requirements of consumers.

Foundry

74-77 440
Abstract

Based on thermodynamic calculations, it is shown that in the temperature range of 298–1273 K, heating and cooling of aluminum are thermodynamically equilibrium processes. When aluminum is heated, the molar volume energy of Gibbs decreases and the molar boundary energy of nanocrystals increases. When aluminum is cooled, the molar volume energy of Gibbs increases and the molar boundary energy of nanocrystals decreases. Liquid aluminum is a nanostructured system. Dendritic microcrystals are formed from nanocrystals. They play a large role in the processes of changing the structure of aluminum during its heating and cooling.

78-81 492
Abstract

The publication highlights the production of artistic castings by investment casting using combined ceramic molds. The features of the application of a refractory coating, duplex curing of ceramic shells, cutting of molds, removal of the model composition, annealing of ceramic molds, pouring and separation of the gating‑feeding system under conditions of mass production are considered. Hydrolyzed ethyl silicate (ETS) and aqueous alkaline silica sol are used as a binder. The hydrolysis is carried out with an acidic catalyst. The strength of forms on an aqueous binder before calcination (bending strength σi) is from 1.5 to 2 MPa. The presented technology allows flexible coverage of the entire range of art products. Castings weighing from 5 to 10 kg can be produced in one batch, which significantly reduces the production cycle.

82-87 311
Abstract

The article presents the results of a study of the effect of vacuuming on the curing processes of liquid‑glass mixtures. The method of conducting experiments using an original laboratory vacuum installation and the mechanisms of curing a liquid‑glass mixture with various hardening methods are described. Studies have shown that vacuuming can signifi antly accelerate the curing and increase the strength of the mixture while reducing the content of the silicate binder. This; in turn; facilitates the knockability of liquid‑glass mixtures and expands the prospects for using these environmental friendly mixtures in foundry as an alternative to sands based on organic binders.

88-90 354
Abstract

The article presents experimental data confirming the effect of capillary active substance (surfactants) and sedimentation stability on the final structure of the gel with stabilized silicic acid. Studies of the macrostructure of silica gel depending on the method of emulsifi ation of silicic acid sol and the effect of the resulting fractality on the strength of the mold are presented.

The direction of modifying the binder for lost‑wax casting (LWC) with obtaining the specified properties of the ceramic shell is shown.

The complex effect of organic polymers on the sol – gel system has been established. The conclusion is made about the possibility of using an aqueous dispersion of acrylic to form a given structure of a silica gel.

Science of materials

91-96 421
Abstract

The article is devoted to a special nanostructured form of carbon – fullerenes; the discovery of which became one of the most important events in the field of physics in the 80s of the last century. The article discusses the issues of obtaining and using fullerenes and other nanostructured materials; including hybrid ones; in foundry and metallurgical production: for modifying casting alloys; binders and auxiliary molding materials; for obtaining ceramic and hybrid nanocomposites; and for other purposes. It also provides information on the creation and operation of the world’s leading research centers specializing in the synthesis and application of nanomaterials in metallurgy and foundry.

97-105 1631
Abstract

The paper presents the results of experimental studies of the structural characteristics of layered composites based on the Fe‑Al system; obtained using various solid‑phase methods of material deformation (hydropercussion stamping; cross‑wedge rolling) and a liquid‑phase (metallurgical) method for producing multilayer composites.

106-111 1949
Abstract

The article presents the waste generated during the production of hot‑dip galvanizing. The results of the study of the particle size distribution of zinc dust showed that its particle size distribution in the size range of particles ≤ 250 μm, the proportion of which is 87 wt.%, corresponds to the fractional composition of standard powder zinc. In ash, the number of particles up to 250 microns in size is approximately 35 wt.%. Studies of the chemical and phase composition of the hot‑dip galvanized waste – zinc dust made it possible to establish that the zinc content of the waste approximately corresponds to powder zinc (GOST 12601). The proportion of pure zinc in dust is 95 %. Chemical and phase analyzes of the ash have shown that it contains zinc oxides, pure zinc and zinc chlorides. Zinc chlorides, in turn, can be a supplier of chlorine ions in thermal diffusion galvanizing. In this regard, it is of interest to use ash in the composition of the powder composition as an activating and zinc‑containing component. The results of the analysis of the conducted studies of hot‑dip galvanizing wastes – zinc dust and soot show that they are promising for their use as components in saturating mixtures in the production of zinc coatings by chemical‑thermal treatment. This will reduce the cost of galvanized products and ensure the recycling of zinc into industrial circulation.

Protection of labour

112-117 354
Abstract

The method of a comprehensive assessment of the working conditions of workers in foundries is given. The main production factors of working conditions are determined and a relative complex indicator is introduced that takes into account the considered factors of working conditions. Correction coefficients for each production factor are determined, taking into account their impact on the human body.

The equation for calculating the complex indicator was obtained, which made it possible to establish classes of foundries (sections) according to working conditions. The results of calculations of the complex indicator for noise and total for all production factors in foundries with different production patterns are presented.

118-122 424
Abstract

The classification of production factors of working conditions at the workplaces of the main equipment used in the foundry is given. This classification is developed on the basis of the results of the conducted research and based on the materials given in the domestic and foreign literature.

This allows us to evaluate the technological processes and equipment used in the design and reconstruction of foundries (sections) to ensure the most favorable working conditions.

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123-124 223

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ISSN 1683-6065 (Print)
ISSN 2414-0406 (Online)