Техніка в сільськогосподарському виробництві, галузеве машинобудування, автоматизація. Випуск 31. - 2018

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    Розмірна обробка електричною дугою бічної поверхні напрямного ролика з композиційного матеріалу на основі реліту
    (ЦНТУ, 2018) Сіса, О. Ф.; Пукалов, В. В.; Свяцький, В. В.; Сиса, О. Ф.; Свяцкий, В. В.; Sisa, O.; Pukalov, V.; Sviatskyi, V.
    Виконано обґрунтування технологічної схеми формоутворення зовнішньої бічної поверхні напрямного ролика, способом розмірної обробки електричною дугою з урахуванням особливостей фізичних механізмів їх утворення та гідродинамічних явищ в міжелектродному проміжку. Встановлені аналітичні зв’язки технологічних характеристик процесу розмірної обробки електричною дугою твердого сплаву «Реліт» з режимами обробки і геометричними параметрами. Выполнено обоснование технологической схемы формообразования внешней боковой поверхности направляющего ролика, способом размерной обработки электрической дугой с учетом особенностей физического механизма образования и гидродинамических явлений в межэлектродном промежутке. Установлены аналитические связи технологических характеристик процесса размерной обработки электрической дугой твердого сплава «Релит» с режимами обработки и геометрическими параметрами. The article is dedicated to development of technology and equipment of rough machining method by electric arc of a guide roller side surface, as high performance alternative to traditional methods of rough machining. During operation, the damage to the surface of the hard alloys guide roller caliber occurs by abrasion and chipping of carbide particles. The development of net shaped roll marks occurs by the occurrence of hotbeds of accelerated cluster abrasion and chipping of smaller particles with subsequent growth of these areas and unification in a closed net shaped roll marks. The turned out particles of hard alloy leave the machining marks on the wire, in such a worn the hard alloy rolling roller does not meet the specified dimensions and it is reground to a smaller diameter by grinding of diamond tool on the rough machining stage. It is proposed on the stage of rough machining to remove the worn-out profile of a guide roller side surface with help of dimensional electric arc, which allows you to remove big allowances of material at the lowest treatment costs. It is suggested to get the lateral surface by dimensional electric arc with a given roughness of Ra = 10..20mkm, which allows you to take great allowances material at the lowest cost processing time.In this case, the processing cycle of hard alloy side surface decreased of 1,4…2,6 times. The justification of technical scheme of forming the guide roller side surface by electric arc sizing method is done taking into account features of physical formatting mechanism and hydrodynamic phenomena in the electrode gap. The analytical communication of technological characteristics of rough machining process by electric arc made of composite material, based on relit, with the modes of processing and geometric parameters are established. The obtained models allow to control the productivity and specific productivity, specific electricity consumption, quality and surface accuracy which is processed, predicted and optimized given characteristics. A technical solution is proposed that allows to expand the technological possibilities of processing the guide roller.
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    Якісні характеристики джерел тепла на сталевих електродах
    (ЦНТУ, 2018) Носуленко, В. І.; Шмельов, В. М.; Шмельов, В. Н.; Носуленко, В. И.; Nosulenko, V.; Shmelyov, V.
    Описано згідно існуючих уявлень в області фізики теплових процесів деякі якісні характеристики джерел тепла на електродах в умовах РОД та їх відповідність експериментальним даним для електродів із заліза та сталей. Можливості та якісні і кількісні характеристики процесу РОД визначаються якісними характеристиками (якістю) джерел тепла на електродах, перш за все, об’ємною густиною теплової потужності, яка, визначається динамічним тиском потоку робочої рідини та полярністю електродів. В зв’язку з цим є можливим легко керувати якістю джерел тепла на електродах, а отже і якістю процесу ерозії, здійснюючи обробку незалежно від струму в широкому діапазоні режимів, починаючи від грубого розмірного плавлення і аж до превалюючого тонкого розмірного випаровування. Описаны согласно существующих представлений в области физики тепловых процессов некоторые качественные характеристики источников тепла на электродах в условиях РОД и их соответствие экспериментальным данным для электродов из железа и сталей. Возможности и качественные и количественные характеристики процесса РОД определяются качественными характеристиками (качеством) источников тепла на электродах, прежде всего, объемной плотностью тепловой мощности, которая определяется динамическим давлением потока рабочей жидкости и полярностью электродов. В связи с этим возможно легко управлять качеством источников тепла на электродах, а следовательно и качеством процесса эрозии, осуществляя обработку независимо от тока в широком диапазоне режимов, начиная от грубого размерного плавления и до превалирующего тонкого размерного испарения. The electric arc is considered as the sum of three independently operating heat sources at the cathode, anode and arc column. At the same time, the qualitative characteristics (quality) of the heat source at the cathode determine the possibility and the qualitative side of the cathode erosion process, and the qualitative characteristics (quality) of the heat sources at the anode are the possibility and the qualitative side of the anode erosion process (treatment). Comparative quantitative and qualitative estimates of heat sources at the cathode and anode, in turn, allow us to draw conclusions about the polarity of electrical erosion, since, as is known, the effect of electric erosion is polar, that is, both quantitatively and qualitatively the erosion of the cathode and anode differ. Create a reliable energy balance for the cathode region and separately for the anode region of the arc, that is, to give a quantitative and qualitative characterization of heat sources separately at the anode and separately at the cathode, using existing classical concepts of elementary processes in the arc, at the present time is impossible. The quality of the heat sources on the electrodes is described by the volume density of thermal power in the cathode and anode heat sources, which, in turn, is determined by the current density and the electric field strength, respectively, in the cathode and anode regions of the arc. The qualities and qualitative and quantitative characteristics of the process of dimensional processing by an electric arc are determined by the qualitative characteristics (quality) of the heat sources on the electrodes, first of all, by the volume density of the thermal power. The latter, in turn, is determined by the dynamic pressure of the flow of the working fluid, as well as, in certain limits, by the polarity of the electrodes. In this connection, it is possible to easily control the quality of the heat sources on the electrodes, and consequently the quality of the erosion process, performing processing irrespective of the current in a wide range of modes, beginning from rough sized melting and to prevailing thin dimensional evaporation. The physical process of electric erosion during dimensional processing by electric arc is characterized by a continuous supply of energy to the treatment zone, continuous burning of the arc and the continuous existence of heat sources at the electrodes. So the thermal effect of the discharge on the electrodes is continuous and the process of erosion is continuously proceeding. Described according to the existing ideas in the field of the physics of thermal processes, some qualitative characteristics of heat sources on electrodes under conditions of dimensional processing by an electric arc and their correspondence to experimental data for electrodes from iron and steels.
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    Підвищення ефективності електродугового різання бідротовим електродом-інструментом
    (ЦНТУ, 2018) Боков, В. М.; Bokov, V.
    Удосконалено та досліджено високопродуктивний спосіб електродугового різання металів бідротовим електродом-інструментами шляхом застосування зворотного прокачування органічного середовища. Усовершенствован и исследован высокопроизводительный способ электродугового резания металлов бипроволочным электродом-инструментом за счёт применения обратной прокачки органической среды. Modern engineering applies electrical, physical and chemical methods for cutting hard-to-treat materials. In most cases it is the process productivity that determines the choice of a cutting method. We know the technological shaping scheme for electric arc cutting which compensates the electric erosion wear of the electrode tool due to the parallel pulling of two electrode tools (that is, a bipolar electrode tool) with the direct pumping of process water through the front inter-electrode gap clearance. However, the direct pumping creates conditions for the concentration of torsion products in the lateral gap clearance. As a result, long arcs appear which, on the one hand, form an inclined cutting surface and increase cutting time, and, on the other hand, they destroy the electrode holders. Besides, technical water, as the process water, partially conducts electric current. Due to this part of power linked up with the electrode is not effectively used/ The objective of the work is to increase the efficiency of electric arc cutting with a bipolar electrode tool by applying reverse pumping of the organic medium. We know the technological scheme for shaping which compensates the wear of the bipolar electrode tool due to its pulling in the cutting zone, in which the direct pumping of process water is used. However, the application of this technology creates conditions for the concentration of erosion in the lateral inter-electrode gap clearance. As a result, long arcs appear that form an inclined cutting surface and destroy the electrode holders. And the leakage of current (through water) reduces the cutting performance. The work suggests a new technological shaping scheme for the electric arc cutting by a bipolar electrode tool which uses reverse pumping and organic medium. The new scheme allowed eliminating the above-mentioned disadvantages of the known scheme. Experimental research was carried out and mathematical models of technological characteristics which allow managing and predicting productivity, accuracy and quality of electric arc cutting have been obtained. Thus, a high-performance method of electric arc cutting of metals by a bipolar electrode tool has been studied and improved by using reverse pumping of the organic medium.