The  

Electro  

Magnetic  

Pulse  

Technology  

(EMPT)  

has  

a  

wide  

range  

of  

applications,  

which  

are  

not  

restricted  

to  

electro-magnetic

forming.  

Both  

welding  

(i.e.  

atomic  

bonding)  

and  

joining  

by  

a  

mechanical  

interlock  

are  

possible.  

  

  

You  

can  

use  

our  

EMPT  

machines  

for

processing  

of  

tubular  

components  

made  

from  

steels  

or  

high  

strength  

alloys  

even  

with  

a  

large  

wall  

thickness  

to  

diameter  

ratio.  

You

can  

use  

them  

also  

for  

non-magnetic  

metals  

such  

as  

aluminium  

and  

copper,  

because  

an  

eddy  

current  

is  

temporarily  

induced  

in  

the

work piece.

Lorem Ipsum Dolor Lorem Ipsum Dolor Lorem Ipsum Dolor

The EMPT

1 . Metal forming by electro-magnetic fields? 2 . Is this really possible? 3 . Welding and joining without distortion and heat affected zones? 4 . Can it be done in an industrial environment? 5 . Can we implement this?   We reply to all these questions with a clear “YES”...

What are the Underlying Physical Principles of EMPT?

Lorem Ipsum Dolor

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Some  

time  

elapses  

while  

the  

sinusoidal  

current  

increases,  

until

the  

first  

displacement  

of  

the  

cross  

section  

towards  

a  

smaller

diameter  

takes  

place.  

During  

this  

period  

stresses  

inside  

the

specimen  

increase  

rapidly,  

until  

their  

amplitude  

is  

sufficient  

to

overcome  

the  

yield  

strength  

of  

the  

work  

piece  

as  

well  

as  

its

inertia.   

Successively,   

the   

diameter   

reduction   

rate   

is   

rapidly

increased,  

causing  

an  

end  

of  

the  

forming  

process  

prior  

to  

the

zero point of the first half wave of the electrical current.

An  

alternating  

current  

in  

the  

range  

of  

100kA  

can  

be  

supplied  

by

a  

pulse  

generator  

and  

is  

essential  

for  

the  

generation  

of  

the

high-flux  

magnetic  

field.  

The  

pulse  

generator  

is  

assembled  

of  

a

bank   

of   

capacitors,   

switches   

and   

associated   

charging   

and

control  

devices.  

The  

first  

step  

to  

start  

a  

forming  

operation  

is  

to

charge  

the  

capacitors,  

and  

this  

lasts  

less  

than  

10  

seconds.

Afterwards,  

a  

high-current  

switch,  

which  

separates  

coil  

and

capacitors, is closed.

Now,  

the  

current  

oscillates  

at  

high  

frequency  

between  

capacitor

and  

coil.  

This  

set-up  

is  

capable  

to  

generate  

altering  

current  

in

the  

range  

of  

some  

100kA  

up  

to  

more  

than  

1  

Mega  

Ampere.

Due  

to  

the  

capacitor  

charging  

time,  

the  

pulse  

generator  

can  

be

operated    

through    

a    

conventional    

380V/32A    

socket.    

The

electricity  

for  

a  

PS60  

system  

(60kJ)  

costs  

only  

approximately

0.0015€ per pulse.

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Current  

carrying  

conductors  

are  

affected  

by  

a  

force,  

when

placed  

in  

a  

magnetic  

field.  

This  

force  

is  

called  

the  

Lorentz

force.  

Moreover,  

current  

carrying  

conductors  

will  

generate  

a

surrounding   

magnetic   

field.   

Hence,   

two   

parallel   

wires   

will

experience   

an   

attractive   

force,   

in   

case   

of   

equal   

current

conduction   

direction.   

Otherwise,   

the   

conductors   

are   

forced

apart,  

if  

the  

currents  

run  

in  

opposite  

directions.  

The  

same

phenomenon  

happens,  

if  

a  

metallic  

tube  

is  

placed  

in  

a  

coil,

through   

which   

an   

alternating   

current   

runs   

(AC).   

The   

coil

induces  

a  

counter-  

rotating  

eddy  

current  

in  

the  

tube  

according

to Lenz’s law.

In  

conjunction  

with  

the  

coil’s  

magnetic  

field  

the  

induced  

eddy

current  

causes  

a  

repulsive  

force  

in  

radial  

direction,  

as  

shown  

in

the figure.

The   

induced   

eddy   

current   

and

magnetic   

force   

are   

represented

for  

the  

duration  

of  

one  

half  

wave

of  

the  

altering  

current.When  

the

current’s   

polarity   

is   

altered,   

a

counter-rotating   

eddy   

current   

is

induced   

once   

again   

within   

the

tube.

Thus,   

there   

are   

no   

changes   

in   

direction   

of   

the   

resulting

magnetic   

forces.   

Because   

of   

the   

component’s   

inertia,   

the

forming  

operation  

is  

phase  

delayed  

with  

respect  

to  

the  

time-

current function.

The       

figure       

illustrates       

the

numerically      

calculated      

cross-

sectional    

shape    

of    

an    

EMPT-

specimen.