TPT May 2007

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Tube B ending, Hydroforming & End-Fo rming
142 May/June 2007
Bend Tooling Inc, USA, is a manufacturer
of die sets, mandrels, and wipers for rotary-
drawing tube-bending. The draw bending
method produces high-quality tube bends
and, unlike compression or ram bending,
the draw method fixes the line of tangency
in space. This allows tooling to be fixtured
at the point of bend where the tubing
material becomes plasticised as it is drawn
through the line of tangency.
The mandrel is of central importance
in controlling the flow of this plasticised
material before it sets into a bend. In fact,
the draw method is so closely associated
with the use of a mandrel, it is often called
‘mandrel bending’.
The key to maximising the performance
of the mandrel is the ‘forward-mandrel’
set-up. The three factors to consider are
the diameter of the mandrel nose (n), the
radius of the nose (m), and the position of
the nose relative to the line of tangency (S).
These values are calculated using a formula
comprising of mandrel nose diameter {n = t
– (w x 2.21)}, mandrel nose radius {if F<50
then m = n x 0.1, else m = n x 0.02, where
F = t / w}, and set-up position of mandrel
nose {S = sqrt ((r + (t / 2) – w)2 – (r + (n /
2))2) + m}.
Bend Tooling’s website features a ‘Four-
step setup procedure’ section, with further
information on how to optimise mandrel
setup. The website also features ‘The bend
tooling encyclopedia’, with definitions of the
terms used in this article.
Bend Tooling Inc – USA
Fax: +1 616 454 9958
Email:
Website:
Forming and bending
equipment for the US market
KGK International Corp, USA, was
established in 1981 to import quality
machine tools from Japan to the US and
Canadian markets. In addition to the Okuma
range of machine tools, KGK International
supplies Nissin’s precision 3D tube bending
machine and Nihon Spindle spinforming
and flowforming machines.
The Nissin 3D tube bender ensures highly
improved productivity with a bending radius
of over 360º. Available in three models, the
machine offers large radius bending from
5/16" to 2 3/8" diameter.
The machine is operated by placing a tube
through the die without a special mold or die
change. Radius and bending directions can
easily be input on the user-friendly controller.
The bending section is securely guided by
the die so that accurate roundness can be
obtained on the cross section.
KGK International Corp – USA
Fax : +1 847 465 0181
Email:
Website:
Set-up secrets for mandrel bending
fi Tooling is fixed at the point of bend where the
tubing material becomes plasticised