The average weight of
passenger cars have increased by 40% in the last 30 years essentially because of safety
features that have been gradually built in over the years and have now become standard. As
a result of the increase in weight, gaseous emissions and fuel consumption have also
increased. Legislations will soon not only cap emission levels, but will also force
reduction. The10-year long ultra-light steel auto (ULSA) programmes for body (ULSAB),
structure (ULSAS) and advanced vehicle concept (AVC) under the International Iron &
Steel Institute (IISI) has shown that use of high strength steels (HSS) and advanced HSS
(AHSS) can bring down car weight by 35% and yet meet safety standard and costs. The use of
AHSS will mean use of new technologies such as tailor welded blanks (TWB) and hydroforming
of sheets and tubes. Hydroforming is already being used worldwide for auto components. The
Indian auto industry is also actively experimenting with hydroforming of components. This
article introduces tube hydroforming as a new technology about to happen in India.
Introduction
Tube forming process at the Tubes Mill |
Tube
hydroforming is a manufacturing process in which an internal hydraulic pressure is applied
to transform either a straight or a pre-bent tubular blank into a structural component
with different or varying cross-sectional shapes along its length. High pressure tube
hydroforming is the most common form of the tube hydroforming process in which a tubular
blank is placed in a closed die and an internal hydraulic pressure forces the tube to
conform to the shape of the die cavity. Punches may also be mounted in the die to pierce
holes in the tube wallduring the forming operation.
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