OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 3 2022 Introduction Nowadays additive technologies are actively developing all over the world and are increasingly being used in industrial production. The overall growth of the additive technology market is more than 20 % annually. Additive manufacturing is based on a new effi cient concept of digital production, in which there is a close link between all stages of product design and production, ensured by the presence of a digital prototype of the product and the application of end-to-end design principles. Powders or wire materials are used for printing metal components. The use of powders makes it possible to obtain the fi nal product with complex geometry and high surface quality, but the application of these technologies is constrained by the high cost of powder materials and low productivity. The use of wire as a starting material allows achieving high process productivity and a signifi cant economy compared to powder technology due to the use of a cheaper wire material. The use of electron beam in the additive processes of directed energy input, the so-called Directed Energy Deposition (DED) technologies, has several advantages, the main among which are the fl exibility of controlling the spatial and energy characteristics of the thermal source and the availability of a vacuum protective medium [1–5]. Such technologies began to be actively used in industry since the early 2000s for the production of jet engine parts, turbine blades and other items made of structural steel and nonferrous alloys [5–10]. The combination of these technologies with subsequent machining allows achieving high part production effi ciency compared to traditional technologies. The product manufacturing stage is preceded by preliminary simulation in order to determine the parameters of the product manufacturing technology to ensure the required performance characteristics. At the same time, the reliability of simulation results largely depends on the quality and adequacy of the process model used. The possibility of simulation of the technological process is of high interest and is a reserve for optimizing the technological modes of parts manufacturing, developing control programs, minimizing defects and improving the quality of manufacturing of complex parts. One important factor in electron-beam additive technology processes that use wire deposition is the wire feed orientation. The standard scheme for additive electron-beam deposition is the electron-beam melting of a wire fi ller material fed laterally into the electron-beam zone. This additive electron-beam deposition scheme does not provide uniform thermal infl uence in the deposited area because the electron beam does not interact with part of the deposited surface as a result of its shading by the fi ller wire. A number of models of this process have been developed dedicated to the analysis of heat and mass transfer processes during additive shaping [11–14]. The most effective variant for electron-beam deposition is vertical wire feeding, which provides the most stable formation of the welding pool and, accordingly, the deposited beads. In this case, to melt vertically fed wire, it is advisable to use two electron beam guns that melt the fi ller wire symmetrically. In work [15] a mathematical model of the melting process of vertically fed wire material by two symmetrically arranged electron beams without taking into account the vapor pressure forces, as well as additional process parameters, such as the location and angle of the heat sources, which has a signifi cant impact on the results of numerical simulation of the welding pool formation and the hydrodynamic processes occurring in it. In accordance with this, the purpose of this work was to conduct numerical experiments for qualitative analysis and determination of the basic regularities of formation of deposited beads, the modes of fi ller material transfer and the dependence of geometric characteristics of the deposited beads on the infl uence of the vapor pressure forces, the relative position of the deposition vector and the plane of electron beams and the value of the azimuth angle of the heat sources. Research methods During additive electron-beam deposition with two symmetrically acting electron beams in the process of substrate motion, different variants of the location of the plane in which the electron beams act, relative to the deposition rate vector and the value of the azimuthal angle of the heat sources are possible.
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