Welding and Forming of Sheet Metals by Using Magnetic Pulse Welding (MPW) Technique
4th International Conference on High Speed Forming (ICHSF2010) March 9-10, Columbus- Ohio, USA (2010)
Tokyo Metropolitan College of Technology, Tokyo, Japan
Mehrdad KASHANI, Tomokatsu AIZAWA and
Keigo OKAGAWA
1) Introduction
2) Principle of MPW 3) Experimental Setup 4) Experimental Results 5) Conclusions
6) Future Plan
OUTLINE
Hybrid structures of aluminium alloy and steel are suggested for reducing the weight of automobiles to improve fuel efficiency and control air pollution. Therefore, joining steel and aluminium alloy in different shapes is receiving attention.
0 1 2 3 4 5 6 7 8 9 10
Melting Point Density Electrical
Conductivity Thermal
Conductivity Machinability
Steel(=1) Aluminum
Factor
Comparison of Aluminium and Steel
INTRODUCTION
INTRODUCTION
History:
Magnetic Pulse Welding process was developed in the late
1960s and early 1970s for nuclear energy applications. Russian
scientists at the Kurchatov Institute of Nuclear Physics invented a
technique for pulsed magnetic welding of end closures of nuclear
fuel rods.
INTRODUCTION
Magnetic Pulse Welding Benefits and Advantages
Use for several dissimilar metals joints combination
Eliminates localized annealing
Heat-free solid-state welding process
Less Joint weight
No filler material is needed
Joint interface is stronger than the weakest material
….
PRINCIPLES OF MPW
Coil
a
a = 5mm
Current
C G
Impulsive Current
Electro magnetic force
Eddy current
Magnetic flux
High electric current is applied to the coil Magnetic flux occurs
Eddy current is generated in the Al plate.
Electromagnetic force causes the Al plate fly.
The Al plate crashes into the Fe plate, and
they are jointed
Current
C G
Coil Parent
plate (Fe)
Flyer
plate
(Al)
PRINCIPLE OF MPW
=
−
− −
=
∂
− ∂
=
×
∇
δ ωκµ
δ τ µ
κ
) 2 (
exp 2 2 1
)
( 2
depth skin
pressure B P
t i B
The eddy current i and the magnetic pressure p are given as following:
i = Eddy current B = Magnetic Field
P = Magnetic Pressure κ= Electrical conductivity μ= Magnetic permeability τ= Thickness
ω= Angular frequency
MPW Device Description
Control system Trigger system
Coi l
D isc ha rg e s w itc h
Cap ac itor
Ch ar ge r swit ch
H igh v olt ag e So ur ce
Current G
C
Coil
G: Gap Switch
C: Capacitor Bank = 12-200μF Charging Voltage= 2-5kV
Total Inductance = 30nH Discharge Energy= 0.8-4kJ
Target Metal
Base
Metal
Experimental Setup
ａ
ｂ
Ｃ Ｃ Ｇ
Ｇ Current
Fixture Gap Before Welding
Al sheet Insulator sheet
Coil
coil
Current ａ＝ 130 mm
ｂ＝ 5 mm
Steel(SPCC)
MPW Device Description
Ｃ
Ｇ Current
Fixture
Base Metal Coil
Target Metal collision time
measurement Circuit
Oscilloscope Rogwoski coil
High Speed Camera Observation Area
Diagnostics setup
MPW Device Description
Flat Coil Perpetration
1
2 3
Current Current
Current
Coil Cross Section
Magnetic Field
MPW Device Description
MPW Device Description
MPW Process
Typical Discharge current and collision time
6.2μｓ
Maximum Current:
160kA
Bank Energy:
2.5kJ
Base and Target Metal Collision Time:
6.2mS
Speed of Base Metal just before collision:
480m/s Current
Collision time
MPW Process
Observation of Base and target Metal Collisions time by a High Speed Camera
Coil
Target Metal
Base Metal
Configuration Before Welding
3mm Gap
High Speed Camera
Flash
Coil Base Metal
Target Metal
MPW Process
Observation of Base and target Metal Collisions time by a High Speed Camera
The Average Velocity of Base Metal Just before collision:
200-500m/s
MPW Process
The Impact Region Produced By MPW
Base Metal
Interface Layer
Collision Point
Target Metal
Metal Jetting
MPW Process
Simulation of Magnetic Pressure
Experimental Results
Typical macrostructure of joined interface zone for A1050/A1050 and A5052/SPCC
Weld Geometry
Steel(SPCC)
Al-A5052
Eddy current path 1mm
1mm
Al-A1050
Al-A1050 Al-A1050
Al-A1050 100 µm
Steel(SPCC)
Al-A5052 100 µm
Experimental Results
SEM image of joined interface for A6016/SPCC sample
Weld Geometry
SPCC
A6016
1mm
Experimental Results
Electron Probe Micro-Analysis (EPMA)
SPCC
A1050 Al 5µm
CP 5µm
Fe 5µm
