Browsing by Author "Dzharov V."

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    Automation of the electron-beam welding process
    (2016-04-07) Koleva E.; Dzharov V.; Kardjiev M.; Mladenov G.
    In this work, the automatic control is considered of the vacuum and cooling systems of the located in the IE-BAS equipment for electron-beam welding, evaporation and surface modification. A project was elaborated for the control and management based on the development of an engineering support system using existing and additional technical means of automation. Optimization of the indicators, which are critical for the duration of reaching the working regime and stopping the operation of the installation, can be made using experimentally obtained transient characteristics. The automation of the available equipment aimed at improving its efficiency and the repeatability of the obtained results, as well as at stabilizing the process parameters, should be integrated in an Engineering Support System which, besides the operator supervision, consists of several subsystems for equipment control, data acquisition, information analysis, system management and decision-making support.
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    Electron beam deflection control system of a welding and surface modification installation
    (2018-04-05) Koleva E.; Dzharov V.; Gerasimov V.; Tsvetkov K.; Mladenov G.
    In the present work, we examined the patterns of the electron beam motion when controlling the transverse with respect to the axis of the beam homogeneous magnetic field created by the coils of the deflection system the electron gun. During electron beam processes, the beam motion is determined the process type (welding, surface modification, etc.), the technological mode, the design dimensions of the electron gun and the shape of the processed samples. The electron beam motion is defined by the cumulative action of two cosine-like control signals generated by a functional generator. The signal control is related to changing the amplitudes, frequencies and phases (phase differences) of the generated voltages. We realized the motion control by applying a graphical user interface developed by us and an Arduino Uno programmable microcontroller. The signals generated were calibrated using experimental data from the available functional generator. The free and precise motion on arbitrary trajectories determines the possible applications of an electron beam process to carrying out various scientific research tasks in material processing.
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    Modelling of the mechanical properties of steel 316L after EB treatment
    (2018-10-19) Dzharov V.; Koleva E.; Vassileva V.; Yordanova R.; Yankova S.
    Investigation of the variation of the mechanical properties of 316L steel after electron beam surface modification is performed. The samples were processed at an installation in IE BAS - ELIT - 60. The irradiated plates were with thickness of 0.5 mm. The experiments were carried out with a change in the beam power in the range of 0.6 to 0.9 kW and different irradiation times between 1 to 120 seconds. Regression analysis was performed on the obtained results.