Finnland Joining 2007 by mSOkHM6

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									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
                    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
                 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)
    Pulse technological processes and their
                  parameters
Kinds of pulse      Typical ratline             Pressure and Time
technological
                    pressure-time     Pm, MPa           ta, s         tk, s
processes
Types of
explosion:                             5∙104           1∙10-6       …1∙10-3
-contact                               1∙104           1∙10-6       …1∙10-3
- in water                             5∙103          500∙10-6      …5∙10-3
- unlimited

Electro-hydraulic                                                    100…
                                       300           1…10∙10-6
effect                                                              200∙10-6



Electromagnetic
impulse (direct)                       100          20…50∙10-6      500∙10-6
Generation of pulse electromagnetic field




       1 – transformer           5 – tube
       2 – rectifier             6 – detail
       3 – capacitor’s battery   7 - coil
       4 – discharger
                     Theoretical background

The electromagnetic force in the coil is determined by following equation:

                                   f v   j  H 
where j and H are the vectors of current density in the coil and
electromagnetic intensity; μ is the magnetic inductivity.
Impulse current
                                 i  I me t sin t
where Im is the current amplitude; ω is the circular frequency of discharge current; t is
the time of current influence.
The electromagnetic field intensity on surface of conductor respectively is determined
as:                             H  H e t sin t
                                   1       m

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:
                                       p  1 H 12
                                            2
                     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.
Main parameter range of IEG
Equipment to the magnetic impulse compaction
                                   MIK-500
              MIU-40
                                   W = 0,5 kJ
              W = 40 kJ
                                   U = 0,8 kV
              Umax = 6 kV
                                   1-60 imp/min
              1-30 imp/min



               MIU-6
               W = 6 kJ
               Umax = 6 kV         MIK-300
               1-600 imp/min       W = 0,3 kJ
                                   U = 0,8 kV
                                   1-30 imp/min
       Inductors for concentration
          of the magnetic field




Spiral inductor
                                  Inductor with the
                                  concentrator and
                                    water cooling




                  Flat inductor
            MIC for powder coating




                         Pipe with an internal powder coating

                             D0 = 16 mm, D1 = 13 mm,
                                  L = 80-300 mm.
 Preform of a worm         Shell – copper, capillary - iron
wheel with an external
 coating of Fe-C-Cu
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.
Magnetic pulse joining experintal research

 1. Assembly diagram
 2. Estimation of adhesion strength
 3. Factors of the influence
                        Assembly diagram




  Scheme of the built-up of powder           Scheme of the assembling of powder detail
detail: 1 – detail; 2 – rod; 3 – inductor;   by expansion on the inside: 1 – inductor; 2
      4 – pulse current generator                    – powder detail; 3 – bush
           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)
Concentration of impulse magnetic field




    Concentrator      Changing of magnetic induction
              Deformation of powder materials




                                                before sintering




                                                after sintering
                                                and MIC

Changing of electromagnetic pressure on
  thickness of the detail from powder
Deformation of sintered materials


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



    3
        Assembly of details




One-piece connections of details from diverse materials
             Cu-steel, Al-bronze, Cu-Al
MIOM application in powder metallurgy




  Part with unidirectional steel fibers in copper   Macrostructure of fibers built-up onto
               holder (d = 0.7 mm)                    the copper holder (D = 0,7 mm,
                                                                d = 15 mm)




         Assembling of bronze filters in            Welds of the pipes (copper-steel,
                copper case.                               copper-titanium)
                           Conclusions

1.   Magnetic pulse joining method makes it possible to extend the field of
     application of powder metallurgy.

2.   Features of the method enable one to press powder layers on steel
     compacts made by casting or forming.

3. 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.

4. MIOM method is more effective in assembling of details from
   heterogeneous materials.

5. The optimal parameters must be determined in each MIOM process.

								
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