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FÜGEN VON ALUMINIUM
Fügen von Aluminium im Automobilbau
Weil die Schweißtechnik die wichtigsten
Verfahren zum Verbinden
metallischer Einzelteile im Automobilbau
liefert, ist es nicht verwunderlich,
dass ein Hersteller von
Schweißgeräten zu diesem Thema
eine internationale Fachkonferenz
einberuft. Diese Konferenz hat auf
Einladung von Fronius Anfang Oktober
2008 in Sattledt, Österreich,
stattgefunden. Über 150 Experten
aus verschiedenen Ländern präsentierten
und diskutierten Lösungen,
die auch über den Rahmen
der Schweißtechnik hinausgingen
und sich auf Verfahren bezogen,
bei denen keine thermische Beeinflussung
des Grundwerkstoffs (wie
beim Schweißen) stattfindet. Zwölf
Referenten von Automobilherstellern
(u. a. Audi, BMW, Daimler,
Ford, Volkswagen), von Zulieferfirmen,
Stahlherstellern und
Forschungsinstituten gaben einen
Einblick in die moderne Werkstoff-
und Fügetechnik des Automobilbaus.
Hier sollen die wichtigsten
Aussagen der Tagung wiedergegeben
werden, soweit sie den Werkstoff
Aluminium betreffen.
Das Fügen metallischer Einzelteile zu
einem Bauwerk ist ein Spezialgebiet,
das technische Laien in der Regel
nicht besonders interessiert. Sie verlassen
sich darauf, dass die Fachleute
es schon richtig machen. Und setzen
sich daher beruhigt in ihr Auto, fühlen
sich darin sicher und denken, dass
eine steife Fahrgastzelle mit ausreichend
dimensionierten Knautschzonen
drum herum von den Konstrukteuren
richtig berechnet und von den
Fertigungsingenieuren richtig gefertigt
worden ist. Dazu gehört natürlich
auch, dass die zahlreichen Einzelteile
des Bauwerks „Automobil“ richtig zusammengefügt
worden sind, deshalb
viele Jahre dynamischer Belastung
aushalten und sich im Falle eines
Aufpralls nicht in einzelne Stücke
zerlegen. Bedenkt man dann noch,
dass das Automobil möglichst leicht
sein soll (damit es weniger Treibstoff
benötigt) und dass deshalb die unterschiedlichsten
Werkstoffe eingesetzt
Joining of aluminium in automotive engineering
Since welding technology is the
most important method for joining
individual metallic components in
automotive engineering, it is hardly
surprising that a manufacturer
of welding equipment convened
an international technical conference
on the subject. At the invitation
of Fronius the conference took
place at the beginning of October
2008 in Sattledt, Austria. More
than 150 experts from various
countries presented and discussed
solutions, which also extended
beyond the scope of welding technology
and related to methods in
which the basis material is not
affected by heat (as it is during
welding). Twelve speakers from
automobile manufacturers (Audi,
BMW, Daimler, Ford Hyundai,
Volkswagen), supply companies,
steel producers and research
institutes reviewed modern material
and joining technology in the
context of automobile engineering.
This article reproduces the most
important information presented
at the conference, insofar as it
concerns aluminium.
The joining of individual metallic
components to produce a structure
is a special field, which is not generally
of great interest to laymen. They
assume that technicians will already
have done this properly, and so they
calmly get into their car, feel safe in
it, and consider that a rigid passenger
compartment with appropriately
dimensioned crumple zones around it
has been correctly calculated by the
designers and properly constructed
by the production engineers. This
of course includes the fact that the
numerous individual components of
the ‘automobile’ structure will have
been joined together effectively and
will therefore withstand many hears
of dynamic loading and, in the event
of a crash, will not fall apart into individual
pieces again. But if it is borne
in mind that the automobile should
also be as light as possible (so as to
consume less fuel) and that therefore
materials of the most varied types
are used in it, and also that the very
large production runs involved compel
process automation, then even
laymen can begin to understand the
great challenges faced by joining technology
in the context of automotive
engineering.
Trends in joining
and materials technology
Which joining method is used in individual
cases, and for which components,
depends on the materials
involved. Steel is still the dominant
material used for auto body construction.
The steel industry has
developed a whole range of special
steels with which the aim of weight
reduction in automotive engineering
can be achieved: high-strength, higher-strength
and ultra-high-strength
grades, whose abbreviations (e. g.
TRIP 1 steel or TWIP 2 steel) only mean
something to steel specialists. At any
rate, the steel industry has thereby
managed to defend itself against competition
from other, lighter materials.
From the regular publications on
the subject, readers of this journal
know that in this competition aluminium
plays an important part. This
concerns not only parts of the engines
and the drive system, but to an
increasing extent also other vehicle
components. There is hardly a new
passenger car design which does not
contain more aluminium components
than its predecessor. To give only one
current example: in the new 7-series
BMW, on the one hand the proportion
of high-strength and ultra-highstrength
steels in the body has been
increased, but on the other hand a
lot of aluminium is used: the engine
crankshaft housing and the rear axle
transmission housing, large parts of
the front and rear axle assemblies,
parts of the brake system, the roof
1 TRansformation-Induced Plasticity
2 TWinning-Induced Plasticity
46 ALUMINIUM · 12/2008