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What
is meant by "bend radius at tube centre
or profile centre"?
The most widely adopted system in the industry
is to measure the bend radius at the centreline
of the tube.
Alternatively, the radius can be measured at the
inside or outside of the tube, although this system
is less widespread.
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What
is the difference between an outside diameter
of a tube quoted in inches GAS or inches OD?
Inches Gas and inches OD are two different measurement
systems used for specifying the outside diameter
of a tube. The two systems are not directly connected
[e.g. as when temperature is measured in degrees
Centigrade or degrees Fahrenheit]. To be sure that
the tube diameter is correctly specified in order
to select the required machine or tooling, always
specify the equivalent outside diameter in millimetres.
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Which
parameters do I need to know in order to select
the most suitable tube bender and tooling for
a specific job?
You must know the outside diameter of the tube
[mm], the wall thickness [mm], the required bend
radius [in mm if possible] and the tube material
[specify the DIN/AISI/UNI definition of the material].
It is also helpful to know the quantity of bends
to be produced per day.
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What
do the expressions 2D, 3D or similar mean in
the context of a bend radius?
"
D" refers to the outside diameter of the
tube to be bent. Therefore, a 2D specification
indicates
that the bend radius is twice the outside diameter
of the tube. Example: a tube with 50 mm outside
diameter bent with a 2D radius will have a bend
radius of 2 x 50 = 100 mm.
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What
is meant by "spring-back angle"?
For example, to obtain a 90° bend angle the
machine must be set up to bend the tube to 95 or
98° because when it is removed from the machine
it will tend to "relax" slightly and
reduce the bend angle set on the machine.
The difference between the bend angle of the
finished part and the bend angle set on the machine
is referred
to as the "spring-back angle".
-
What is the maximum angle to which a part can
be bent?
Machines with rotary bending systems can be used
to obtain a maximum bend of 180 degrees plus an
additional maximum correction angle [spring-back]
of 30 degrees [total angle 210 degrees]. In contrast,
ram benders can be used to obtain a maximum angle
of 90 degrees plus a correction angle [spring-back]
of approximately 10 degrees.
