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Victor Mironov, Irina Boyko Riga Technical University , Riga , Latvi a

JOINING OF POWDER DETAILS BY MEANS OF PULSED ELECTROMAGNETIC FIELD. Victor Mironov, Irina Boyko Riga Technical University , Riga , Latvi a. Lappeenranta , Finland, 2 1 -24 August , 2007. Contents. 1. Introduction 2. Theoretical background 3. Pulsed electromagnetic field 4. Equipments

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Victor Mironov, Irina Boyko Riga Technical University , Riga , Latvi a

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  1. JOINING OF POWDER DETAILS BY MEANS OF PULSED ELECTROMAGNETIC FIELD Victor Mironov, Irina Boyko Riga Technical University, Riga, Latvia Lappeenranta, Finland, 21-24 August, 2007

  2. Contents 1. Introduction 2. Theoretical background 3. Pulsed electromagnetic field 4. Equipments 5. MIOM application in PM 6. MIOM for production of composite materials 7. MIOM assembling 8. Conclusion

  3. Introduction MIOM – Magnet-impulse metal machining (USA, Germany) DMC – Dynamic Magnetic Compaction (Russia, USA) EMF – Electromagnetic forming (USA, Russia, Germany) PMW – Pulse Magnetic Welding (Germany, Russia) MIPP – Magnetic Impulse Pressing of Powder(Russia, Latvia)

  4. Pulse technological processes and their parameters

  5. Generation of pulse electromagnetic field 1 – transformer 5 – tube 2 – rectifier 6 – detail 3 – capacitor’s battery 7 - coil 4 – discharger

  6. Theoretical background The electromagnetic force in the coil is determined by following equation: where j and H are the vectors of current density in the coil and electromagnetic intensity; μ is the magnetic inductivity. Impulse current where Im is the current amplitude; ω is thecircular frequency of discharge current; t is the time of current influence. The electromagnetic field intensity on surface of conductor respectively is determined as: where Hm is the maximal value of intensity ; α is the attenuation coefficient. The pressure of electromagnetic forces on the surface of billet with high electric conductivity can be calculated as:

  7. Testing and control The electromagnetic field is induced in the gap between the coil and the plate at the instant an electric discharge of the capacitors. Scheme of compaction of a material in a rigid mold. 1 – impact plate; 2 – surge current generator; 3 – surge current generator; 4 – electromagnetic transducer; 5 – inductor with a winding; 6 – compacted material; 7 – mold.

  8. Main parameter range of IEG

  9. Equipmentto the magnetic impulse compaction MIK-500 W = 0,5 kJ U = 0,8 kV 1-60 imp/min MIU-40 W = 40 kJ Umax = 6 kV 1-30 imp/min MIU-6 W = 6 kJ Umax = 6 kV 1-600 imp/min MIK-300 W = 0,3 kJ U = 0,8 kV 1-30 imp/min

  10. Inductors for concentration of the magnetic field Spiral inductor Inductor with the concentrator and water cooling Flat inductor

  11. MIC for powder coating Pipe with an internal powder coatingD0 = 16 mm, D1 = 13 mm, L = 80-300 mm.Shell – copper, capillary - iron Preform of a worm wheel with an external coating of Fe-C-Cu

  12. Manufacture of complex-shaped components by the magnetic pulse compaction method There is proposed method of preparing the multilayer components of tool. Working part consists of hard alloy (3) or steel (1), another of iron-copper alloy (2). Dimensions of parts can be increased due to using step pressing. To rise the density and the efficiency of the used forming envelope, it is expedient to use the infiltration method. 1 3 2 2 Components consisting of several parts: a) worm-wheel compact; b) inserts of mold dies. 1 – wheel, 2 – Fe-C-Cu ring, 3 – WC-Co insert.

  13. Magnetic pulse joining experintal research • Assembly diagram • Estimation of adhesion strength • Factors of the influence

  14. Assembly diagram Scheme of the built-up of powder detail: 1 – detail; 2 – rod; 3 – inductor; 4 – pulse current generator Scheme of the assembling of powder detail by expansion on the inside: 1 – inductor; 2 – powder detail; 3 – bush

  15. Adhesive shearing strength Correlation between adhesive shearing strength depending on the energy level of the capacitive storage device W, rod surface roughness Rz and gap between details δ. MIOM device of discharge frequency 6 kHz. Energy levels: W=6 (1),W=8 (2),W=10 (3)

  16. Concentration of impulse magnetic field Concentrator Changing of magnetic induction

  17. Deformation of powder materials before sintering after sintering and MIC Changing of electromagnetic pressure on thickness of the detail from powder

  18. Deformation of sintered materials 1 • Copper tube D0 = 80 mm, δ0 = 2,0 mm • Preform from iron powder apparent density – 2,45 g/cm3, green density – 5,8 g/cm3 • Iron powder after MIC(green density – 7,2 g/cm3) 2 3

  19. Assembly of details One-piece connections of details from diverse materialsCu-steel, Al-bronze, Cu-Al

  20. MIOM application in powder metallurgy Part with unidirectional steel fibers in copper holder (d = 0.7 mm) Macrostructure of fibers built-up onto the copper holder (D = 0,7mm, d = 15 mm) Assembling of bronze filters in copper case. Welds of the pipes (copper-steel, copper-titanium)

  21. Conclusions • Magnetic pulse joining method makes it possible to extend the field of application of powder metallurgy. • Features of the method enable one to press powder layers on steel compacts made by casting or forming. • Application of electromagnetic pulsed field in plastic deformation of metallic materials and in powder metallurgy gives new possibilities in producing of mechanical engineering and instrument-making details. • MIOM method is more effective in assembling of details from heterogeneous materials. • The optimal parameters must be determined in each MIOM process.

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