Purpose. Analysis of surface-hardening technology for cold processing of metals, taking into account the deformation-wave processes occurring in the area in front of the shaping tool. Methodology. To establish the reasons for obtaining finished products with increased roughness, insufficient contact strength, fracturing and peeling of the surface layers, as well as the occurrence of significant dynamic loads in the mechanisms of machines for machining parts using plastic deformation, a two-mass design model is used in which the working tool is connected by friction with the moving processed workpiece. Findings. The results of determining the conditions for the occurrence of self-oscillations in the system “workpiece - tool” are presented. Based on the analysis of the friction characteristics as a function of the mutual slip rate between the workpiece and the shaping tool, the range of slip speeds is set, at which the self-oscillating processes for the friction pair can be excited: "tool - workpiece". Originality consists in the fact that the influence of the variable friction force on the occurrence of sustained self-oscillations between the workpiece being processed and the tool in the machines for “cold” plastic deformation of the metal has been established. The conditions for the occurrence and absence of self-oscillations in the zone of contact between the tool and the workpiece are found. Practical value lies in the fact that the modes of operation of machines for processing products by plastic deformation have been revealed under which unregulated roughness, fracturing and “peeling” of the parts being machined can occur, as well as a high dynamic background during the operation of the shaping tool of driving and power mechanisms. Practical recommendations are given to improve the performance of finished products and reduce vibroactivity in the drive. Keywords: running in, dragging, knurling, plastic deformation, elastic deformation wave, roller, tool, blank.
When drilling blast wells in the technological process of mining magnetite quartzites, the cost of a cone bit is about 60% of the cost of the entire drilling tool. The work includes a literature review of modern methods of increasing the reliability of drilling tools. It has been established that the main directions for increasing the performance of cone bits are the use of wear-resistant materials and coatings for their production, improvement of drilling technology and the organization of repair and preventive maintenance. In the work, it is proposed to use MATEХ (Canada) drilling chemistry, which has found wide application in the oil and gas industry and in granite quarries during impact drilling. The research was carried out in a quarry for the extraction of magnetite quartzites on an Epiroc DM-75E drilling rig, drilling chemicals were fed into the water-air mixture using a MATEХ dispenser. The drilling chemical dispenser is completely self-contained and easy to install on the drilling machine, designed with only one moving part, which ensures low operating costs. Industrial studies with the use of MATEХ drilling chemistry (the consumption of chemistry was 1.5 liters per hour) showed a significant increase in the working hours of cone bits, on average, from 745 to 1488 linear meters. Conclusions were made regarding the use of MATEХ drilling chemistry in the conditions of iron ore quarries of the private joint-stock company «Northern Mining and Processing Plant» (Kryvyi Rih). Experimental studies showed the expediency of using drilling chemistry when drilling blast wells for the extraction of magnetite quartzites. Due to the increase in the working time of cone bits, a reduction in the cost of drilling 1 linear meter of blasting wells by 38.7% was achieved
Purpose. Substantiation of the role of longitudinal and transverse wave processes in the surface layers on the quality of finished products obtained by plastic deformation methods, such as cold rolling, stamping, running in, drawing and others. Research methodology. In the work, to describe the transients at the beginning of the interaction of the tool with the workpiece, a computational model was applied in which the surface layers of the workpiece are represented as a beam on an elastic base, loaded with suddenly applied tangential forces, often exceeding their critical values. The reasons for the occurrence of unstable dynamic states of such a beam, in which the integrity of the surface layers of the workpiece and parts may be disturbed due to the occurrence of supercritical stresses and deformation in the material of the outer layers, are investigated. Findings. The results were obtained on the definition of hazardous states of the surface layers of the workpiece, under the action of suddenly applied loads at the initial moments of the capture of the workpiece, as well as at the moments when the tool slips over the workpiece during the alignment of their speeds. Originality. It consists in the fact that the first dynamic problem was set and solved for the surface layers of the workpiece, represented as a two-support beam on an elastic base loaded with a suddenly applied longitudinal force, which can significantly exceed its critical value. Denoted areas of dynamic instability of the surface layers of the workpiece. The practical value of the work lies in the fact that the modes of operation of the metal forming machine and the parameters of the workpiece were identified under which conditions for obtaining products of insufficient quality may arise. As well as developed recommendations for improving the quality of finished products. Key words: metal forming, transients, longitudinal wave, shear wave, billet, loaded layer, overload coefficient, dynamic buckling, tool, rolling, knurling, drawing, hypothetical beam, impact, elastic wave propagation velocity.
The article reveals topical issues of export specialization of regions in context of modern technologies. The interaction of the main indicators and changes in the degree of diversification of the commodity export basket was investigated. The changes in the structure of Russian export in the period 2006-2016 was analyzed in 76 regions. The results of the study showed that the unemployment rate in Russia will not change. Conclusions about the structural dynamics of the export basket of remote regions are made. The dependence of the change in the share of products of the fuel and energy complex in the export structure on oil prices was analyzed. The article substantiates the need for a detailed study of the dynamics of diversification of individual product groups.
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