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Information × Registration Number 0219U003155, 0117U007259 , R & D reports Title New high-tech power-saving energy source for precision welding, brazing and surface treatment of materials popup.stage_title Head Bolotov Maksym, Registration Date 23-01-2019 Organization Chernigiv National University of Technology popup.description2 The project is pointed at the solving of the actual scientific problem of creation the new high-technological resource-saving and resource-saving power source for diffusion welding and brazing on basis of the distributed gas-discharge plasma of glow discharge. The object of the scientific work is low-temperature distributed gas-discharge plasma as power source for diffusion welding and brazing processes. The subject of the scientific work is the physical-technological and energy characteristics of glow discharge and the methods of their control under welding heating conditions. The aim of this project is the determination and improvement of technological properties and energy rates of medium pressures glow discharge plasma and controlling means of them under high-temperature heating and metal processing. The main tasks of the work are: 1. The investigation of the stable existence high-current glow discharge area under welding heating conditions; 2. The investigation of the energy and thermalphysic characteristics of glow discharge plasma under welding conditions; 3. The development of methods and controlling means of energy and thermalphysic characteristics of glow discharge in welding, brazing and surface treatment technological processes. During execution of the project complex approach with usage of the theory of gas discharge physics, electrodynamics, electromagnetism and transitional process in electric fields is provided. The main idea of the development of such power source is the ensuring of high energy efficiency and manufacturability of diffusion welding and brazing. It is achieved by realization in the vacuum camera of the high-current medium pressures glow discharge with (1.3…13.3 kPa) as surface heating source which allows to implement the heating both metal and non-metal products in different variations of their combinations with energy coefficient of efficiency at level of 75-80 %. On the basis of the diffusion welding specifics analysis and available data about medium pressures glow discharge (1.3…13.3 kPa), as a working hypothesis during the development of the new heat source for diffusion welding the next propositions: 1) massive cathodes (which are products) are the active heat flow towards discharge plasma and influence on the plasma heating process; 2) the state of gas-discharge and its transitions into contrary mode (electric arc) are determined by the processes on the cathode; 3) discharge plasma as a heating means possesses high technological adaptability; 4) existence of gas-discharge plasma in the wide range of gas pressures allows to realize in the sole technological cycle the operations of purification and activation of the joined surfaces, diffusion welding and thermal or chemical-thermal treatment of welded products; 5) the main parameters of glow discharge are regulated by electric signals which is the base for the process automation; 6) usage of quasi-impedance voltage inventors in the structure of mean power sources for diffusion welding by glow discharge will allow to raise the coefficient of efficiency of the system and improve consumption current quality. It was shown and experimentally confirmed for the first time the efficiency of stabilization of energy release of the distributed plasma of the high-current glow discharge in the conditions of high-temperature heating at welding, brazing and surface chemical-heat treatment of dissimilar metals. It is due to the formation in the interelectrode gap of separate discharge channels operating in parallel with increased electrical resistance, which provides the ability to self-regulation of the discharge current and limits the unpredictable redistribution of its density with the achievement of critical values in the heating area on the surface of welded parts. It was established for the first time that the prevention of the development and stabilization of the arc discharge at any point of the heating area with a distributed multi-channel discharge system is achieved by the sequential engaging of the powering of electrodes of the discharge sections. It is provided by the use of a movable electric field, which frequency is determined by providing conditions in the discharge gap. In such conditions, it is difficult to form repeatedly of the conductivity channel with an arc discharge, which in the range of welding modes corresponds to the rotation frequency of the electric field of 500-2000 Hz. For the first time, the possibility of increasing the stabilization of the glow discharge in the conditions of precision welding and brazing by including an external active resistance in the discharge circuit was proposed. It was experimentally established that the calculated value of such resistance in the range of discharge currents 2...8 A, the gas pressure of 2.66... 13.3 kPa is 0.8...1.1 resistance values of the discharge gap and in the absence of technological disturbances ensure the stability of the set heating mode for limited discharge capacity - up to 4...5 kW. Distinctive features of the developed device for stabilization of the glow discharge in installations for welding, soldering and surface treatment of materials with the usage of multisection electrode system it is that individual sections of the anode are equipped with a transformer sensor of the arc current pulses. The primary winding of such sensor is series connected to the electric supply circuit of the glow discharge. It is also the anode are equipped with an electromagnet, the ferromagnetic core of which is the metal rod of the anode section holder. In the nearest foreign analogue [Trousil. Zone melting in a glow discharge /Czechoslovak journal of physics. -1962. - №3, Vol. 12., series B (in English)] in order to prevent the formation of an arc discharge on the surface of the connected parts and reduce its harmful effect, individual anode sections are moved relative to the product manually. To increase the sensitivity of the device to the signal of the emerging arc, the coil of the electromagnet can be included in the initial circuit of the voltage amplifier, which made according to the electronic switch scheme, the input circuit of which is connected to the output of the arc current pulse sensor. The usage of this device can significantly reduce the size of the power source of the glow discharge, increase the speed of operation of the device at the time of the electric arc, improve the quality of welded products and ensure high performance of the process. The results obtained in the course of the second stage of the research work will ensure the stable existence of the medium pressure glow discharge within the selected shape in the welding and brazing processes throughout the isothermal heating cycle. It is due to the use of technical facilities of the discharge current stabilization on the basis of an arc-quenching system. In turn, the latter will significantly improve the productivity of the process of obtaining diffusion-welded joints of parts made of materials significantly differ in physical and mechanical properties and have limited or unsatisfactory ability to weld. The results obtained during the second phase of the research work, in particular, the methods of stabilization of glow discharge by extinguishing of arc are applied in educational process of department of welding technology and CAD/CAM/CAE systems of building structures during the laboratory works on discipline "Electro-technological processes and installations". Product Description popup.authors Болотов Геннадій Павлович Гречка Володимир Миколайович Деркач Олег Леонідович Меркулов Владислав Олександрович Нагорна Ірина В'ячеславівна Петрушинець Лідія Вячеславівна Ювченко Андрій Сергійович Ющенко Світлана Михайлівна popup.nrat_date 2020-04-02 Close