Вісники та науково-технічні збірники, журнали

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Author: search.filters.author.Dragašius, Egidijus

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    Simulation and analytical studies of chip formation processes in the cutting zone of titanium alloys
    (Видавництво Львівської політехніки, 2023-02-28) Stupnytskyy, Vadym; She, Xianning; Dragašius, Egidijus; Baskutis, Saulius; Prodanchuk, Oleh; Lviv Polytechnic National University; Kaunas University of Technology
    The low machinability of titanium alloys is determined by the physical, mechanical, and chemical properties of these materials and their mechanical characteristics. It is also evident in the hardened state of the material being processed during cutting and in the initial state. This phenomenon is caused by thermodynamic parameters that determine the properties of titanium material at elevated temperatures. The peculiarities of the cutting and chip formation processes during titanium alloy machining are presented in this article. The peculiarity of the described approach is the analysis of the results of simulation modeling of cutting in Deform 2D software. It is proved that the frictional factor in the formation of the thermal characteristics of the cutting process, which arises as a result of the chip sliding along the tool, dominates the load factor (caused by force and deformation processes in the chip root). It has been established that the length of contact between the chips and the tool’s rake face has a certain tendency to change: the contact length first increases and then decreases with increasing cutting speed. An analysis of the dependence of the chip compression ratio on changes in cutting speed has shown that with an increase in cutting speed, the average value of the compression ratio practically does not change, but the amplitude of its oscillation increases significantly, which is equivalent to a change in the shear angle. This parameter changes dynamically due to the adiabatic nature of chip formation.
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    Modeling and simulation of machined surface layer microgeometry parameters
    (Видавництво Львівської політехніки, 2022-02-22) Stupnytskyy, Vadym; Dragašius, Egidijus; Baskutis, Saulius; Xianning, She; Lviv Polytechnic National University; Kaunas University of Technology
    The formation of the microtopography of the machined surface is one of the most critical factors in ensuring the effective operating properties of the product. These are indicators such as wear resistance, fatigue strength, provision of friction parameters of moving joints, etc. The most important reason for the formation of microroughness is vibration in the technological surface of the machine-tool-tool-tool-workpiece. This article is devoted to describing a new method of modelling the dynamic processes of machining. The peculiarity of this technique is using the results of rheological modelling (DEFORM). In addition, the consideration of regenerative vibrations of the tool is the difference of the described model. Regenerative oscillations arise due to surface roughness, which will be processed as a result of the previous technological stage of mechanical treatment. The mathematical model and the research results are described in the article. Recommendations for reducing oscillations are given.