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Metalworking № 5 (149)/2025 |
MATERIAL CUTTING
Abstract. The article considers issues related to the use of molybdenum and the features of its processing in electronic engineering as a heat-resistant material used to manufacture dies used to form a singlecrystal profile in the production of profiled leucosapphire using the Stepanov method. It shows the possibility of using electrical discharge machining to manufacture dies from sheet molybdenum, as well as ways to improve the technology and equipment for electrical discharge machining of molybdenum. The results of experimental studies and the criteria for the optimal parameters of the electrical discharge process are discussed. Recommendations are given for the selection of pulse duration, pulse repetition rate, voltage on the capacitor bank, polarity on the electrode-tool and the workpiece, the material of the electrode-tool for use as the base for selecting the parameters of electrical discharge machining of sheet molybdenum. Keywords: electrical discharge machining, electrical discharge process, molybdenum, electrodetool, die, leucosapphire
Abstract. The paper proposes and substantiates a combined technology of surface grinding, consisting of traditional flat grinding by the periphery of the wheel and surface plastic deformation (SPD) of the workpiece while it leaves the cutting zone for each double stroke. В As a result of the tech-nology application, metal displacement will be reduced during the operation of the single abra-sive grains, reduce the surface roughness of the workpiece and also reduce the greasing of the grinding wheel. The results of simulation modeling of PPD by balls with the surface of the workpiece. Key words: flat grinding, grinding marks, pile factor, grinding wheel salting, surface plastic deformation METAL FORMING
Abstract. The possibilities of reducing the forces of cold volume stamping by extruding parts such as bushings with bottom by using punches with rational shapes of their working ends are shown. The forces are reduced by shaping the bottoms of the extruded cavities at the extrusion stage, facilitating the flow of the deformed metal into the wall of the extruded bushing with bottom. As a result, the fatigue resistance of the punches extruding the cavities decreases and the coaxiality of the external and internal cavities of the manufactured parts is ensured. Keywords: cylindrical bushings with bottom, cold extrusion, rational shapes of cavity ends, reduction of extrusion forces, reduction of wall thickness variation of products Yu. V. Zamaraeva, Yu. N. Loginov, O. F. Degtyareva, A. V. «Razinkin Influence of stress state on cracks formation in protector thickening at light alloy pipe extrusion» Abstract. As a result of industrial extrusion of light alloy drill pipes with a protector thickening, 9.8% of the pipes have longitudinal cracks on the outer surface in the protector thickening. In the course of the work, three variants of modeling this process were carried out, and the distribution of tangential stresses was considered, as well as the index of the stress state was calculated as one of the causes of the longitudinal crack formation. It was found that the temperature decrease of the workpiece metal by 40 °C has a negligible effect, while the decrease of both temperature by 40 °C and the tool speed by 0.5 m/s during the protector pressing contributes to more favorable values of tangential stresses and index of the stress state. A real experiment on pipe extrusion after adjusting the temperature and speed regime led to a 2-fold decrease in the percentage of defects due to the „longitudinal cracks” defect. Keywords: aluminum, drill pipes, protector thickening, extrusion, stress state, tangential stresses, longitudinal cracks
NEW MATERIALS AND TECHNOLOGY
Abstract. Formation of ordered distributions of crystallographic orientations (textures) in polycrystalline materials occurs during various processes of thermomechanical treatment. The presence of texture in materials leads to anisotropy of physical and mechanical properties of manufactured samples. To analyze the degree of development of textural components in polycrystals, texture parameters are proposed, the calculation of which is performed based on the cold deformation texture of yttrium (technical yttrium, brand ИтM-1). Yttrium ingots were deformed by cold rolling with different degrees of compression up to 60%. The intensities of crystallographic orientations were measured on a DRON-0.5 X-ray diffractometer using Cu-Ka radiation (operating voltage 35 kV). The main method of X-ray examination of samples was the inverse pole figure method. The proposed texture parameters made it possible to analyze the processes of texture formation in cold-rolled yttrium, to assess the degree of development of the forming texture components, and to draw a conclusion about the operating mechanisms of plastic deformation. A conclusion was made about the expediency of using the proposed texture parameters for practical use for the purpose of rapid assessments of textures and anisotropy of material properties during technological processing. Keywords: texture, x-ray methods, diffractometer, polycrystals, yttrium, ingot, plastic deformation, cold rolling
Abstract. The technology of finishing magnetic abrasive treatment (MAO) of flat surfaces of flat-oval pipes made of aluminum alloy AMc has been developed to improve the quality of soldered joints of heat exchangers. As a result of the conducted multifactorial experiment, optimal processing modes were established: magnetic induction, processing time, tool rotation speed, feed, allowing to achieve a surface roughness of Ra = 0.608–0.650 microns. Regression dependences have been obtained that adequately describe the effect of technological parameters on the output roughness. It is shown that the use of MAO provides the required surface roughness, flatness and minimum thickness of the oxide film, which is necessary for subsequent high-quality soldering. Keywords: magnetic abrasive treatment, aluminum alloy, soldering, surface roughness, permanent magnets, flat-oval pipe, mathematical modeling, optimization of modes
DESIGN OF TECHNOLOGICAL SYSTEMS
Abstract. The analysis of the definitions for term „Mechanical engineering technology“ in the meanings of „science“ and „academic discipline“ for their compliance with the requirements for terms and definitions is carried out. It is shown that the name of the term, characterized by the word-terms it consists of, does not correspond to the scope and content of the concepts of „Mechanical engineering technology“ as a science and as an academic discipline, represented by their definitions in scientific, educational and reference literature: the semantics of the term is violated. Their new definitions are proposed and a conclusion is made about the need to bring regulatory scientific and educational documents in the field of „Mechanical engineering technology“ in line with the terminologically correct content and scope of this term. Keywords: technology, mechanical engineering technology, term, definition, requirements for terms and definitions, science, scientific specialty, curriculum, academic discipline, textbook |