Vol. 24 No. 2 2022 3 EDITORIAL COUNCIL EDITORIAL BOARD EDITOR-IN-CHIEF: Anatoliy A. Bataev, D.Sc. (Engineering), Professor, Rector, Novosibirsk State Technical University, Novosibirsk, Russian Federation DEPUTIES EDITOR-IN-CHIEF: Vladimir V. Ivancivsky, D.Sc. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Vadim Y. Skeeba, Ph.D. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Editor of the English translation: Elena A. Lozhkina, Ph.D. (Engineering), Department of Material Science in Mechanical Engineering, Novosibirsk State Technical University, Novosibirsk, Russian Federation The journal is issued since 1999 Publication frequency – 4 numbers a year Data on the journal are published in «Ulrich's Periodical Directory» Journal “Obrabotka Metallov” (“Metal Working and Material Science”) has been Indexed in Clarivate Analytics Services. We sincerely happy to announce that Journal “Obrabotka Metallov” (“Metal Working and Material Science”), ISSN 1994-6309 / E-ISSN 2541-819X is selected for coverage in Clarivate Analytics (formerly Thomson Reuters) products and services started from July 10, 2017. Beginning with No. 1 (74) 2017, this publication will be indexed and abstracted in: Emerging Sources Citation Index. Journal “Obrabotka Metallov” (“Metal Working & Material Science”) has entered into an electronic licensing relationship with EBSCO Publishing, the world's leading aggregator of full text journals, magazines and eBooks. The full text of JOURNAL can be found in the EBSCOhost™ databases. Novosibirsk State Technical University, Prospekt K. Marksa, 20, Novosibirsk, 630073, Russia Tel.: +7 (383) 346-17-75 http://journals.nstu.ru/obrabotka_metallov E-mail: metal_working@mail.ru; metal_working@corp.nstu.ru
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 4 EDITORIAL COUNCIL EDITORIAL COUNCIL CHAIRMAN: Nikolai V. Pustovoy, D.Sc. (Engineering), Professor, President, Novosibirsk State Technical University, Novosibirsk, Russian Federation MEMBERS: The Federative Republic of Brazil: Alberto Moreira Jorge Junior, Dr.-Ing., Full Professor; Federal University of São Carlos, São Carlos The Federal Republic of Germany: Moniko Greif, Dr.-Ing., Professor, Hochschule RheinMain University of Applied Sciences, Russelsheim Florian Nürnberger, Dr.-Ing., Chief Engineer and Head of the Department “Technology of Materials”, Leibniz Universität Hannover, Garbsen; Thomas Hassel, Dr.-Ing., Head of Underwater Technology Center Hanover, Leibniz Universität Hannover, Garbsen The Spain: Andrey L. Chuvilin, Ph.D. (Physics and Mathematics), Ikerbasque Research Professor, Head of Electron Microscopy Laboratory “CIC nanoGUNE”, San Sebastian The Republic of Belarus: Fyodor I. Panteleenko, D.Sc. (Engineering), Professor, First Vice-Rector, Corresponding Member of National Academy of Sciences of Belarus, Belarusian National Technical University, Minsk The Ukraine: Sergiy V. Kovalevskyy, D.Sc. (Engineering), Professor, Vice Rector for Research and Academic Affairs, Donbass State Engineering Academy, Kramatorsk The Russian Federation: Vladimir G. Atapin, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Victor P. Balkov, Deputy general director, Research and Development Tooling Institute “VNIIINSTRUMENT”, Moscow; Vladimir A. Bataev, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Vladimir G. Burov, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Aleksandr N. Gerasenko, Director, Scientifi c and Production company “Mashservispribor”, Novosibirsk; Sergey V. Kirsanov, D.Sc. (Engineering), Professor, National Research Tomsk Polytechnic University, Tomsk; Aleksandr N. Korotkov, D.Sc. (Engineering), Professor, Kuzbass State Technical University, Kemerovo; Evgeniy A. Kudryashov, D.Sc. (Engineering), Professor, Southwest State University, Kursk; Dmitry V. Lobanov, D.Sc. (Engineering), Associate Professor, I.N. Ulianov Chuvash State University, Cheboksary; Aleksey V. Makarov, D.Sc. (Engineering), Corresponding Member of RAS, Head of division, Head of laboratory (Laboratory of Mechanical Properties) M.N. Miheev Institute of Metal Physics, Russian Academy of Sciences (Ural Branch), Yekaterinburg; Aleksandr G. Ovcharenko, D.Sc. (Engineering), Professor, Biysk Technological Institute, Biysk; Yuriy N. Saraev, D.Sc. (Engineering), Professor, Institute of Strength Physics and Materials Science, Russian Academy of Sciences (Siberian Branch), Tomsk; Alexander S. Yanyushkin, D.Sc. (Engineering), Professor, I.N. Ulianov Chuvash State University, Cheboksary
Vol. 24 No. 2 2022 5 CONTENTS OBRABOTKAMETALLOV TECHNOLOGY Timofeev S.P., Grinek A.V., Hurtasenko A.V., Boychuk I.P. Machining technology, digital modelling and shape control device for large parts..................................................................................................................... 6 Shlykov E.S. ,Ablyaz T.R.. Muratov K.R. Theoretical simulation of the process interelectrode space fl ushing during copy-piercing EDM of products made of polymer composite materials................................................ 25 Loginov Yu.N., Shimov G.V., Bushueva N.I. Deformations in the nonstationary stage of aluminum alloy rod extrusion process with a low elongation ratio.............................................................................................. 39 Sundukov S.K. Features of the superposition of ultrasonic vibrations in the welding process........................ 50 EQUIPMENT. INSTRUMENTS Podgornyj Yu.I., Martynova T.G., Skeeba V.Yu. On the issue of limiting the irregular motion of a technological machinewithin specifi ed limits.................................................................................................... 67 MATERIAL SCIENCE Burkov A.A., Kulik M.A., Belya A.V., Krutikova V.O. Electrospark deposition of chromium diboride powder on stainless steel AISI 304..................................................................................................................... 78 Gulyashinov P.A., Mishigdorzhiyn U.L., Ulakhanov N.S. Infl uence of boriding and aluminizing processes on the structure and properties of low-carbon steels........................................................................ 91 EDITORIALMATERIALS Guidelines for Writing a Scientifi c Paper ............................................................................................................ 102 Abstract requirements ......................................................................................................................................... 107 Rules for authors ................................................................................................................................................. 111 FOUNDERS MATERIALS 119 CONTENTS
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY Theoretical simulation of the process interelectrode space fl ushing during copy-piercing EDM of products made of polymer composite materials Evgeniy Shlykov a, *, Timur Ablyaz b, Karim Muratov c Perm National Research Polytechnic University, 29 Komsomolsky prospekt, Perm, 614990, Russian Federation a https://orcid.org/0000-0001-8076-0509, Kruspert@mail.ru, b https://orcid.org/0000-0001-6607-4692, lowrider11-13-11@mail.ru, c https://orcid.org/0000-0001-7612-8025, Karimur_80@mail.ru Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2022 vol. 24 no. 2 pp. 25–38 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2022-24.2-25-38 ART I CLE I NFO Article history: Received: 31 March 2022 Revised: 06 April 2022 Accepted: 12 April 2022 Available online: 15 June 2022 Keywords: Polymer composite materials Copy-piercing electrical discharge machining Flushing Sludge Funding The work was supported by the grant of the President of the Russian Federation for state support of young Russian scientists – candidates of sciences No. MK-566.2021.4. Acknowledgements Research were partially conducted at core facility “Structure, mechanical and physical properties of materials”. ABSTRACT Introduction. Polymer composite materials (PCM) are used to improve the mechanical properties and increase the working period of products. For the processing of products made of PCM, the use of electrophysical processing methods is standard. One of these methods is copy-piercing electrical discharge machining (EDM). The use of such methods for processing PCM is due to its high physical and mechanical characteristics and the complexity of processing by blade methods. Considering the fact that the PCM element is a binder – epoxy resin, which is destroyed at the edges of the resulting holes and grooves during EDM, PCM can be considered diffi cult to process. During the EDM of holes in PCM products, the temperature rises, and ineffi cient cooling often occurs in the processing zone. The paper is devoted to theoretical simulation in the Ansys package, which makes it possible to evaluate the impact of fl ushing method on the effi ciency of the EDM of PCM products based on numerical simulation in fi nite element analysis software systems. The aim of the work is to increase the productivity of the processes of EDM for PCM products. Methods. Experimental studies were carried out according to the method of a classical experiment on a copy-piercing electrical discharge Smart CNC machine. The workpiece was processed at a constant voltage U = 50 V, pulse on-time Ton = 100 μs and current: I = 10 A. For theoretical simulation of the fl ow, the ANSYS CFX 20.1 software was used. Flow distribution simulation was carried out at three processing depths (2, 10, 15 mm), as well as at three nozzle inclination angles (15, 45, 75°). Results And Discussion. The analysis of the data obtained showed that in the case of the EDM of PCM, the angle of the location of the fl ushing nozzles should be taken into account in order to increase the productivity of processing deep, blind holes. It is established that the highest performance value is achieved when the nozzles are located at an angle of 15˚. The laminar motion prevails. With this arrangement of the nozzles, the value of the liquid pressure and the removal of the sludge are stable both with the EDM of PCM to a depth of 2 mm, and when processing to a depth of 15 mm. It is noted that for processing holes with a depth of 10 mm or more, it is worth considering the angle of inclination of the fl ushing nozzle for effective processing, it is necessary to remove eroded particles from the gap. In the process of conducting an experimental study, when processing holes with a depth of 15 mm, sticking of sludge to the electrode-tool was observed, as well as the closure of the EDM process, the occurrence of secondary discharges in the processing zone, which caused the processing to stop. For citation: Shlykov E.S., Ablyaz T.R., Muratov K.R. Theoretical simulation of the process interelectrode space fl ushing during copypiercing EDM of products made of polymer composite materials. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2022, vol. 24, no. 2, pp. 25–38. DOI: 10.17212/1994-6309-2022-24.2-25-38. (In Russian). ______ * Corresponding author Shlykov Evgeniy S., Ph.D. (Engineering), Associate Professor Perm National Research Polytechnic University 29 Komsomolsky prospect 614990, Perm, Russian Federation Tel.: 8 (342) 2-198-324, e-mail: Kruspert@mail.ru Introduction The branches of modernmechanical engineering, aviation, oil and gas are associatedwith the introduction of new materials and innovative technologies. It is relevant to develop and improve the effi ciency of processing technologies for new polymer composite materials (PCM), as well as form of the required physical and mechanical properties of products made from these materials [1].
OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 2 2022 Today, there is a diverse range of PCM; new promising materials based on carbon fi ber, developed at FSUE “VIAM”, are of particular interest. One of these materials is carbon fi ber prepreg grade Vku-39/ Vtku-2.200. This material is made on the basis of equally strong carbon fabric grade VTkU-2.200 and binder grade VSE-1212. To process products made of PCM, including carbon fi ber reinforced plastics of the VKU-39, it is advisable to use electrophysical processing methods. Copy-piercing electrical discharge machining (EDM) is one of these methods. The use of such processing methods for PCM is due to its high physical and mechanical characteristics and the complexity of processing by blade methods. Considering the fact that the PCM element is a binder – epoxy resin, which is destroyed at the edges of the resulting holes and grooves during EDM, PCM can be considered diffi cult to process. During the EDM of holes in PCM products, the temperature rises, and ineffi cient cooling often occurs in the processing zone [2–3]. In papers [4-6] the methods and features of the EDM of PCM are presented. On the basis of these works, it is shown that a product made of PCM is subjected to the action of electrical impulses during EDM. The plasma channel appears and has an internal temperature of about 9,000-9,500 °C. This leads to a change in the state of the PCM material. A phase transition occurs from a solid material to a vaporous substance. This subsequently leads to the fact that PCM vapors and molten pieces of electrode-tool (ET) sludge solidify upon cooling and form products of electroerosive sludge, which negatively affects the quality and performance of the EDM [7, 8]. Accumulation of erosive sludge and other erosion products in the zone of EDM of PCM products is caused by poor fl ushing of the space between the ET and the workpiece being processed when deep holes are obtained, as well as slotted and key grooves. This phenomenon leads to the appearance of secondary dendritic structures on the surface of the ET and the workpiece, as well as to a decrease in the EDM quality and productivity when processing products made of PCM [7]. It has been established that the movement of sludge during the EDM of PCM products is formed by the process of formation and movement of gas bubbles in the processing zone [8–11]. Due to the fact that the dielectric (usually mineral or transformer oil) is viscous, electroerosion sludge can move in the shell of the gas bubble. As a result of the studies carried out in [8–11], it becomes possible to show visually the process of erosive sludge movement in the interelectrode space. It is proposed to vary the parameters of the height of the rise of the ET from the zone of the EDM, as well as the speed of the rise of this ET. However, in these works there are no practical recommendations for increasing the productivity and effi ciency of the EDM of PCM products. The structure of erosive sludge is shown in [12, 13]. This sludge is obtained as a result of the destruction of ET and the workpiece material. This forms spherical and hemispherical particles shown in Figure 1, a. The direct formation of the shape of particles in the form of a sphere occurs in the process of cooling the evaporated material of the workpiece. Most of the obtained spherical and hemispherical particles of erosive sludge have a dendritic structure. This indicates the low cooling rates of the EDM process. The formation of erosive sludge from the destroyed ET occurs by thermal crumbling (Figure 1, b). а b Fig. 1. EDM sludge: a – from the workpiece surface; b – from the surface of the electrode-tool
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY EDM sludge particles are subject to destruction. Cracks, dents, as well as zones of crumbling and destruction appear on the surface of spherical particles with an increase in the value of the pulse energy (Figure 2). а b Fig. 2. The surface of spherical sludge particles after destruction: a – at a scale of 5 μm; b – at a scale of 2 μm Local heating of the processed material causes thermal decomposition of the boride phase and the dielectric medium [14, 15]. This dielectric processing medium is in a state of motion and constant circulation. This leads to cooling of the ET and the workpiece material. The fl ow of vapors becomes turbulent and can break up into small fractions. Each part can condense into a liquid, and as a result, into a solid state. The cooling rate of liquid metal drops is reduced by the vapors of the working fl uid that promotes spheroidization and dendritic segregation of particles. The content of the working fl uid and metal vapors decreases at low input energy. This leads to a decrease in the number of particles with a smaller average size. The sludge solidifi es faster if the pulse energies are not high. The fl ow of material vapors and the working fl uid increases along with the values of the input pulsed energy [14, 15]. The movement of sludge particles is turbulent. There is a collision between it. Cracks and dents form on the surface of the particles of this sludge and an inclusion structure also appears. The formation of EDM sludge signifi cantly affects the stability of the EDM process and, as a result, the productivity of processing. Increasing the productivity of the EDM process can be achieved not only by increasing the pulse energy, but also by intensifying the removal of erosion products from the interelectrode gap. Productivity increases with effective fl ushing and intensive removal of eroded particles of PCM and ET from the gap. Flushing brings clean gear oil into the gap and cools the ET and PCM. The deeper the treatment, the more diffi cult it is to ensure proper fl ushing of the zone being processed. This increases processing time and reduces performance. Eroded particles are welded onto a PCM product under certain processing conditions. This leads to uneven processing and reduced performance or even to its stop. Flushing is widely used in EDM of deep holes, including EDM of PCM products. Insuffi cient fl ushing reduces material removal effi ciency. The material that remains in the hole is remelted in the next pulse and welded onto the electrode surface. The intensifi cation of fl ushing during EDM in deep and narrow cavities contributes to an increase in the material removal rate. In [16, 17], it was found that fl ushing maintains the rate of material evacuation after a discharge. In [17], the effect of the ET jump was studied, which is used to evacuate eroded material during immersion under pressure. The electrode movement speed affected the distribution of eroded particles, and the movement amplitude affected the amount of pure dielectric. The work [18] shows the pressure drop of a dielectric liquid at the hole depth, the infl uence of the hole depth on the pressure drop. This was a loss of 15% of the observed 25 mm. Ahigher concentration of eroded material was also established in the corner of the machined hole (Figure 3).
OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 2 2022 Jet or side fl ushing is carried out with tubes or fl ushing nozzles. These nozzles direct the dielectric fl uid into the gap. This is shown in Figure 4. Effi ciency of fl ushing in the case of EDM of deep holes in PCM with a complex geometry of electrode fl ushing channels has not been practically studied in full. Existing models in the processing of PCM by electrical discharge can be obtained using theoretical simulation in fi nite element analysis software systems, including Ansys. An urgent task is to obtain a theoretical model. This model will make it possible to evaluate the infl uence of the fl ushing method on the effi ciency of the EDM of PCM products based on numerical simulation in fi nite element analysis software systems. The aim of the work is to increase the productivity of the process of EDM of products made from PCM. Tasks. 1. Carry out a theoretical analysis of the effect of fl ushing the nozzles of the working fl uid on the process of the EDM of products made from PCM. 2. To carry out an experimental study of the performance of the process of EDM of products made from PCM and verifi cation of the theoretical model of the performance of EDM of products made of PCM. Materials and methods Experimental studies were carried out according to the method described in [4, 5, 19]. ET made of copper M1 was chosen for experiments. The workpiece was made of PCM grade VKU-39. The workpiece was processed on a copy-piercing electrical discharge machine Smart CNC at a constant voltage U = 50 V, pulse on time Ton = 100 μs and current I = 10 A [4, 5, 19]. ANSYS CFX 20.1 software was used for theoretical fl ow simulation. Transformer oil (Engineer oil) was chosen to calculate the main fl ow directions and velocity distribution in the interelectrode gap. The oil temperature was set as standard, equal to 25 oC. For all cases, the pressure was 2.1 kg/cm2 = 0.205 MPa. Flows distribution simulation was carried out at three values of the processing depth (2 mm, 10 mm, 15 mm), as well as at three values of the inclination angle of the nozzles (15°, 45°, 75°) (Figure 2–4). Fig. 3. Partial tracing in the gap between the electrode and the workpiece. The average particle velocity is approximately 0.75 m/s Fig. 4. Scheme of jet or side fl ushing
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY The purpose of the simulation was to obtain a theoretical model for the distribution of working fl uid fl ows in the processing zone, subjected to a change in the angle of fl ushing. To achieve a given purpose in the work, it is necessary to build the geometry of the region of computation; set the boundary conditions of the computation model, compute the model for the processing depth of 2 mm, 10 mm, 15 mm and the location of the nozzles 15˚, 45˚ and 75˚ relative to the tool axis (Figure 5). Fig. 5. Processing model, where H is the depth of processing Fig. 6. Setting geometrical limits The experimental part, carried out in works [4–6], showed that products made of PCM during EDM are prone to sludge fusing on the processed surface. This is due to the irrational location of the fl ushing nozzles and the formation of turbulence in the processing zone. Simulation was performed after specifying the names of the boundary surfaces: part walls, ET and fl ush nozzles. Geometry limits were similar for 10 mm and 15 mm processing, however, only the angle of the nozzles changed (Figure 6).
OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 2 2022 Fig. 7. Mesh model for calculation The computational grid is shown in Figure 7. The minimum and maximum values of a single voxel were set to build the grid: min – 1 mm, max – 5 mm. The same conditions were set for other calculated cases. When modeling, it was assumed that the nozzles would operate at the same pressure and angle relative to the tool axis. For all cases, the pressure was identical and equal to 2.1 kg/cm2 = 0.205 MPa. It is shown that in the processing zone and boundary areas, the grid has taken the minimum values, which should have increased the simulation accuracy. The single-phase oil working fl uid fl ow was modeled using the standard turbulence model (Figure 8). Fig. 8. Calculation construction tree with the fi nal model of the CFXPRE module
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY Oil fl ow geometry was collected using an enlarged image of the electrode cross section and simplifi ed to reduce computation time. The number of elements of the tetrahedral grid varied from 7.8·106 to 6.4·106 in the hole of the workpiece according to the geometry of the volumetric fl ow due to small geometric features within the processing zone. Calculations were carried out in the Ansis Fluid Flow module. Results and discussion Based on the data obtained, it is found that the infl uence of the nozzles angle on the fl ushing effi ciency is not signifi cant when processing a PCM sample to a depth of 2 mm. Figures 9–11 show that the laminar fl ow of the fl uid predominates. With a processing depth of 10 mm, it is found that the laminar movement of the working fl uid prevails for the nozzle located at an angle of 15˚. Turbulence is formed in the processing zone. The fl ows of 2 nozzles collide in this zone. It is noted that for nozzles located at angles of 45˚ and 75˚ turbulence is formed in the interelectrode gap and entails a slight decrease in pressure. Sludge removal from the processing zone is diffi cult (Figures 12–14). Figures 15–17 show that at a working depth of 15 mm for a nozzle located at an angle of 15˚, the laminar movement abruptly turns into turbulent. In the processing zone, the fl ows of the two nozzles collide. Turbulent motion dominates completely. It is established that when processing holes of a given depth and above, the location of the nozzles at an angle of 45˚ and 75˚ relative to the tool axis is inappropriate. This is caused by high fl ow turbulence and loss of transformer oil pressure in the processing zone (Figures 15–17). а b Fig. 9. Depth 2 mm, nozzle angle 15°: a – computation of the pressure of the working fl uid; b – fl ow distribution models а b Fig. 10. Depth 2 mm, nozzle angle 45°: a – computation of the pressure of the working fl uid; b – fl ow distribution models
OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 2 2022 а b Fig. 11. Depth 2 mm, nozzle angle 75°: a – computation of the pressure of the working fl uid; b – fl ow distribution models а b Fig. 12. Depth 10 mm, nozzle angle 15°: a – computation of the pressure of the working fl uid; b – fl ow distribution models а b Fig. 13. Depth 10 mm, nozzle angle 45°: a – computation of the pressure of the working fl uid; b – fl ow distribution models
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY а b Fig. 14. Depth 10 mm, nozzle angle 75°: a – computation of the pressure of the working fl uid; b – fl ow distribution models а b Fig. 15. Depth 15 mm, nozzle angle 15°: a – computation of the pressure of the working fl uid; b – fl ow distribution models а b Fig. 16. Depth 15 mm, nozzle angle 45°: a – computation of the pressure of the working fl uid; b – fl ow distribution models
OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 2 2022 а b Fig. 17. Depth 15 mm, nozzle angle 75°: a – computation of the pressure of the working fl uid; b – fl ow distribution models From the presented fi gures, it can be concluded that when the nozzles are located at 45˚ and 75˚, the turbulent movement prevails. This entails a reduction in pressure. The pressure value for the nozzle at 75˚ does not exceed 0.07 MPa, while the nozzle at 15˚ provides a rational pressure in the processing zone from 0.1 MPa to 0.2 MPa. It is shown that the location of the nozzle at 75˚ for processing holes deeper than 10 mm reduces the pressure in the processing zone by 2 times. For processing holes deeper than 15 mm, the location of the nozzles at 75˚ critically affects the pressure and speed of the working fl uid, and the time of evacuation of eroded particles from the processing zone. This negatively impacts performance. To clarify the theoretical computation, experimental studies were carried out to measure the performance of the EDM of PCM products (Figure 18). Fig. 18. Performance values It is shown that when processing holes with a depth of 2 mm, the value of the fl ushing nozzle angle of inclination does not affect the performance of the EDM. The effect of the infl uence of the nozzles inclination angle is manifested during the EDM to a depth of 10 and 15 mm. A decrease in the value of the productivity of the process of EDM is observed due to the diffi culty in fl ushing the interelectrode space from sludge. The angle of the fl ushing nozzle inclination should be taken into account for processing holes with a depth of 10 mm or more. For effective processing, eroded particles should be removed from the gap. During the experimental study, when processing holes
OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY with a depth of 15 mm, sticking of sludge to the ET is observed, as well as the closure of the EDM process, the occurrence of secondary discharges in the processing zone, which caused the processing to stop. The obtained experimental data confi rm the results of theoretical computation. Conclusion 1. A theoretical model is obtained. This model describes the process of fl ushing the EDM zone for different depths of processing and the location of the nozzles for supplying the working fl uid. 2. It is established that at a processing depth of 2 mm, the location of the nozzles does not affect the quality of fl ushing and the performance of the EDM of PCM grade VKU-39. The laminar fl ow of the fl uid predominates. 3. It is shown that when the EDM of PCM grade VKU-39 to a depth of 10 mm and 15 mm, the location of the nozzles affects the quality of fl ushing and the performance of processing. The highest performance value is achieved when the nozzles are located at an angle of 15˚. For processing holes with a depth of 10 mm or more, the angle of fl ushing nozzle inclination should be taken into account. For effective processing, eroded particles should be removed from the processing zone. When processing at angles of 45˚ and 75˚, turbulent fl uid fl ow occurs. Also, the possibility of secondary discharges arises. The sticking of sludge on the surface of the ET and the occurrence of a short circuit are experimentally confi rmed. This leads to the instability of the process of EDM of products from PCM grade VKU-39. For holes with a depth of 15 mm, the location of the nozzles at 75˚ critically affects the pressure, speed of the working fl uid and the evacuation of eroded particles from the processing zone. This reduces performance. 4. The conducted experimental studies show the effi ciency of the obtained theoretical model. It is established that when processing blind holes with a depth of about 15 mm, it is necessary to set the nozzle angle to 15˚. With this arrangement of nozzles, the liquid pressure values and the sludge output are stable. This ensures the highest productivity in the case of deep hole EDM in products made from PCM grade VKU-39. References 1. Sarde B., Patil Y.D. Recent research status on polymer composite used in concrete – An overview. Materials Today Proceedings, 2019, vol. 18, pp. 3780–3790. DOI: 10.1016/j.matpr.2019.07.316. 2. Yahaya R., Sapuan S.M., Jawaid M., Leman Z., Zainudin E.S. Mechanical performance of woven kenafKevlar hybrid composites. Journal of Reinforced Plastics and Composites, 2014, vol. 33 (24), pp. 2242–2254. DOI: 10.1177/0731684414559864. 3. Thomason J. A review of the analysis and characterisation of polymeric glass fi bre sizings. Polymer Testing, 2020, vol. 85, p. 106421. DOI: 10.1016/j.polymertesting.2020.106421. 4. Shlykov E.S., Ablyaz T.R., Oglezneva S.A. Electrical discharge machining of polymer composites. Russian Engineering Research, 2020, vol. 40, pp. 878–879. DOI: 10.3103/S1068798X20100275. 5. Ablyaz T.R., Muratov K.R., Shlykov E.S., Shipunov G.S., Shakirzyanov T.V. Electric-discharge machining of polymer composites. Russian Engineering Research, 2019, vol. 39, pp. 898–900. DOI: 10.3103/S1068798X19100058. 6. Ablyaz T.R., Shlykov E.S., Muratov K.R., Sidhu S.S. Analysis of wire-cut electro discharge machining of polymer composite materials. Micromachines, 2021, vol. 12 (5), p. 571. DOI: 10.3390/mi12050571. 7. Yilmaz O., Okka M.A. Effect of single and multi-channel electrodes application on EDM fast hole drilling performance. The International Journal of Advanced Manufacturing Technology, 2010, vol. 51, pp. 185–194. DOI: 10.1007/s00170-010-2625-3. 8. Bozdana A.T., Ulutas T. The effectiveness of multichannel electrodes on drilling blind holes on Inconel 718 by EDM process. Materials and Manufacturing Processes, 2016, vol. 31, pp. 504–513. DOI: 10.1080/10426914.20 15.1059451. 9. Haas P., Pontelandolfo P., Perez R. Particle hydrodynamics of the electrical discharge machining process. Pt. 1: Physical considerations and wire EDM process improvement. Procedia CIRP, 2013, vol. 6, pp. 41–46. DOI: 10.1016/j.procir.2013.03.006.
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