Key Engineering Materials Vol. 910

Abstract: Today, under the conditions of sanctions, the Russian Federation needs more than ever the development of energy-saving technologies in various industries. The greatest impact on the life and operability of hard alloy cutting tools is exerted by the physical and mechanical properties of tool materials. Studies have shown that the physical and mechanical properties of tungsten hard alloys in the process of operation, namely in the process of cutting difficult-to-process materials under the influence of high temperatures, vary symmetrically. This study was based on the laws of physics of the division of electrodynamics, as well as well-known non-destructive testing techniques, scientific foundations of materials science, all studies were carried out in accredited laboratories of Tyumen Industrial University. Results of research on determination of temperature of maximum operability of replaceable cutting hard-alloy plates based on study of change of electromagnetic properties are obtained. On the basis of persistent tests in factory conditions, it was proved that the developed technique allows determining temperature intervals of maximum operability based on the study of changes in electromagnetic properties of hard alloys.

Abstract: Ti-based intermetallic compounds are characterized by low machinability, therefore, to obtain accurate dimensions and shape of the surface grinding and Wire EDM are used. The unique properties of NiTi intermetallic alloys are largely influenced by structural phase transformations and variations in microhardness caused by processing accompanied by thermal phenomena. Having an understanding of the physics of the process, it is possible to counteract negative effects, which helps to preserve thermomechanical properties of the final NiTi products. Accumulation of knowledge about the quality of processing with various abrasive tools is part of the larger research presented in this article. Samples of titanium nickelide with a temperature A_f=+25 ⁰С were abraded with ordinary and high porosity SiC wheels. The article studied phase transformations using X-ray diffraction analysis and microhardness. The experimental data were processed using mathematical statistics. X-ray diffraction patterns and microhardness analysis showed that a significant effect on the structural transformation and corresponding increase in microhardness is exerted by grinding with green SiC wheels with normal porosity caused by an increased thermal effect on the surface. Simultaneously, the impact of Wire EDM process on microhardness in preparing workpieces for grinding was evaluated. It was established that grinding of Ti-based intermetallic compounds with memory effect should be performed by SiC wheels with an open structure of high porosity.

Abstract: To study the face milling of hardened steel, the paper considers the chemical composition of the processed material, as well as metal-cutting, measuring equipment and tools. A full factorial experiment of face milling was carried out by the method of mathematical planning and matrices of levels of variation and planning of independent variables were compiled. The flatness of the samples was measured and the causes of plastic deformation were determined. To find an adequate mathematical model of flatness, a regression analysis was performed, and the correlation analysis revealed the closeness of the relationship between the variables under one-and two-factor influence on the response function. The hypersurfaces and lines of the function levels are projected, which made it possible to determine the optimal and effective cutting conditions graphically and analytically.

Abstract: Currently, mathematical modeling applying numerical methods is widely used in the study of metallurgical processes, including metal casting processes in continuous-casting machines. The authors developed a new technology and device for casting metal into a continuous-casting machine mold and metal mixing using the effect of a rotating closed-bottom submerged nozzle with eccentric holes. The theoretical study of processes of mold filling with molten metal was carried out applying a proven numerical method and a special software package. A calculation program was developed based on the numerical schemes and algorithms. The results of calculating metal casting into a rectangular mold are presented as an example. The calculation results are provided in the form of molten metal flow patterns in various sections of the mold.

Abstract: Gear hones are used as tools for gear honing. The efficiency of using gear hones mainly depends on the parameters of their compound material, first of all on the wear resistance and elasticity modulus. In terms of the elasticity modulus, gear hones can be hard and elastic, depending on the bonding agent type. Experience shows that gear-hone teeth distort during gear honing; they feature contact and flexural deformation and wear during metal removal, including along the tooth space. For this reason, it is necessary to consider the deformation and wear values for designing of gear hone geometry. An approach for calculation of variable engagement parameters, using a geometrical model in the form of sliding trapezoids to consider the dimensional wear of gear-hone teeth based on the positive correlation factor of the original profile. Such designing of gear-hone teeth provides sufficient thickness in the original section, which ensures high performance capacity of gear-honing tools and required workability.

Abstract: On the basis of the conducted theoretical and experimental studies, the dependences for determining geometric, physical and mechanical parameters of the surface layer quality, wear resistance and corrosion rate depending on the modes and conditions of electroerosion of machine parts are presented. They allow determining optimal modes and conditions of electroerosion to ensure the required parameters of the surface layer quality (with a two-stage approach it provides design and technological support of operational properties), wear resistance and corrosion rate (with a single-stage approach it makes direct technological support possible).

Abstract: Brittle materials such as ceramics, glass or single-crystal silicon are extensively used for industrial applications and recently become an object of actual research due to the development of new products and technologies. In cases, where special attention is paid to the surface layer, mechanical processing with a diamond tool is of interest as one of the most efficient technology to manufacture products from brittle materials. In this paper, simulation method is presented, which allows to estimate an effect of cutting force on the size of defects zone formed in a hard brittle plate during machining. In the proposed model, there is a distinguished surface layer, which can have its own unique properties that differ from the properties of the brittle plate. In this work, the ANSYS finite element program is used to simulate the technological processes and solve the problem of stress distribution in a quasi-static formulation.

Abstract: The paper considers the dependence of the continuity of the sol-gel coating of carbon fiber on the preliminary anodic oxidation of the surface in a sodium hydroxide solution. The effect of the treatment time, the voltage between the cathode and the anode, NaOH concentration in the electrolyte, and the temperature of the electrolyte was investigated. It is shown that with an increase in NaOH concentration in the electrolyte, the area of uncoated fiber surface sections increases, the continuity of the coating decreases, while the coating obtained without preliminary surface treatment has sufficient continuity of at least 93%. Changes in other parameters (temperature, time, voltage) of preliminary electrochemical surface treatment in the ranges under study did not allow us to fix regularities other than the given one.

Abstract: A technique for studying contact stresses in the connection of heat-exchange tubes with tube sheets using roller rolling is described. Formulas for the determination of contact stresses, taking into account the formation of local deformation of the tube due to force action of each roller and features of axial movement of the tool spindle are given. Calculation was based on the assumption of medium continuity, known relations between normal stresses and deformations, as well as experimental oscillograms of the process.