Modeling of velocities and temperatures processes distribution in the plasma-forming channel determining the design features and optimal parameters of the plasma torch nozzle is one of promising directions in development of plasma technologies. The aim of this work was to simulate the processes of velocities and temperature distribution in the plasma-forming channel and to determine the design features and optimal geometric parameters of the plasmatron nozzle which ensures the formation of necessary direction of plasma flows for generation of surface waves on the surface of a liquid metal droplet under the influence of the investigated instabilities.One of the main tasks is to consider the process of plasma jet formation and the flow of electric arc plasma. For obtaining small-sized particles one of the main parameters is the plasma flow velocity. It is necessary that the plasma outflow velocity be close to supersonic. An increase of the supersonic speed is possible due to design of the plasmatron nozzle especially the design feature and dimensions of the gas channel in which the plasma is formed. Also the modeling took into account dimensions of the plasma torch nozzle, i. e. the device should provide a supersonic plasma flow with the smallest possible geometric dimensions.As a result models of velocities and temperatures distribution in the plasma-forming channel at the minimum and maximum diameters of the channel were obtained. The design features and optimal geometric parameters of the plasmatron have been determined: the inlet diameter is 3 mm, the outlet diameter is 2 mm.The design of the executive equipment has been developed and designed which implements the investigated process of generating droplets of the micro- and nanoscale range. A plasmatron nozzle was manufactured which forms the necessary directions of plasma flows for the formation of surface waves on the metal droplet surface under the influence of instabilities. An algorithm has been developed for controlling of executive equipment that implements the process of generating drops of micro- and nanoscale range.
This work aims to develop technical solutions that allow providing the specified parameters of the accuracy of the shape of parts in the cross-section during processing on a CNC machine. Experimental studies were performed on a screw-cutting lathe. An acoustic signal in the range from 6 to 12 kHz was used as a diagnostic sign to assess the wear of the cutting tool, since during preliminary studies, it was found that this range is most sensitive to changes in processing modes. Studies were performed at different values of wear of the cutting tool (estimated by the width of the wear chamfer). For estimating the life of a cutting tool, a neuro-fuzzy model has been developed. Using models of this class allows adjusting to specific conditions (machine, tool), and correctly evaluating the tool life. The model error for the test sample does not exceed 10%. The test results showed that using the proposed solutions makes it possible to increase the accuracy of the manufacturing of shut-off valve parts by 20-30%.
Growth of the volumes of dangerous and critical welded metal structures constructed under low temperatures imposes additional requirements on the mechanical properties of the weld joints, particularly, on the impact resistance of the weld joint and on the stability of its values. It can be achieved by using coated electrodes with ultradisperse powders of alloying elements in the coating. To develop new improved welding materials we need to optimize the systems of weld metal alloying to meet the increasingly stringent requirements to the welding-operational characteristics. Introduction of a complex ultradisperse powder (Al2O3, SiO2, TiO2, Ni) into the electrode coating applied for manual metal-arc welding ensures more stable process of electrode metal fusing and its transfer into the welding bath, improves the performance characteristics of the welded metal.
The article presents the results of a theoretical study (literature review of publications), which allowed to establish the negative impact of welding aerosol (manganese and other elements) on the human body: you can use special welder protection equipment (ventilation and individual welder protection); reduce the quantitative and qualitative content of manganese welding aerosols (welding technology, power sources, modern welding materials); reduce the content of manganese in the human body, removing it with medicines. Experimental studies have shown that the use of an inverter power source, compared with a diode rectifier, contributes: to ensuring the drop-by-drop transfer of electrode metal to reduce the time of their formation by 46% and the transition by 28%; ensures the transition of alloying elements from welding materials to the weld metal by 6% and reduces its losses from the fusion line by 6% and HAZ by 3%; to reduce the intensity of education (g / min) SA and their components by 23%; to reduce the specific allocation of CA and their components by 23%.
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