Modeling tangential intersections

Modeling tangential intersections
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Modeling tangential intersections .............................................................................. 1
Why tangential contours? ............................................................................................ 1
In Tekla Structures ..................................................................................................... 3
Modeling tangential intersections
Modeling tangential intersections
Modeling tangential
Why tangential contours?
Kersten Europe bv has years of experience in rolling plates and profiles. The way
in which customers deliver their product information, determines the quality, cost
price and time of delivery of the product. Providing correct product information will
not cost extra time for the customer, but they need to know this beforehand.
This article is interesting for you if you want to bend straight profiles or plates with
straight ends or with multiple radii.
What is tangential?
Wrap a rope around a cylinder and pull it tight. The rope
will gradually change from the straight part to the circumferenceradius of the cylinder, wherein the intersection
point is perpendicular to the center of the cylinder. This
intersection is called tangential.
If you want to use a profile with a straight end, you need to connect this straight
end tangential to the radius. If not, differences in dimensions are caused which can
be quite high in size, as described later on in figure 2.
An example of what the differences are:
The following example shows a drawing of a bended box girder with a straight end,
as we received:
Figure 1
At first glance, it all looks good. However, if a bending company starts bending with
this information, it creates a box girder with a bended contour according to figure 2.
In figure 2, the drawing has been placed on top of the bended profile.
Why tangential contours?
Figure 2
As you can see, the end of the bended product is not in the position mentioned on
the drawing. The difference amounts to 84 mm. What causes this difference and
how to prevent this?
We check the drawing by creating a line from the center point of the radius to the
end of the radius and we measure the angle between this line and the straight part,
we see that this angle is 88°. This means that the straight end is drawn buckled.
Figure 3
To bend the box girder according to the desired contour, Kersten Europe will adapt
the original drawing whereby a tangential geometry is determined.
Figure 4
In figure 4, the intersection point from the bended contour to the straight line is
moved 260 mm. This means in practice that the bended product is not equal to the
original drawing anymore. As far as the contour you will not see this difference in
practice. However, this might cause difficult problems if connections are required
on the beam afterwards, because in practice you will have a shorter straight part
than expected, according to you own production drawing.
To avoid this, it is important to create the intersection points tangential from round
to straight and from round to round. You will get what you expect and there are no
extra costs for re-drawing afterwards.
How to create tangential intersection points in Tekla Structures will be explained
Why tangential contours?
In Tekla Structures
In Tekla Structures you can model curved beams and plates. This could be a
simple contour containing 1 radius and 1 straight leg or 1 radius and 2 straight
legs, for example, see the following examples:
There are also a lot of contour-combinations possible:
To improve the exchange of information and to make sure that these kinds of
contours can be bended perfect, whereby no differences in dimensions occur and
double work is prevented, these contours must be modeled "tangential".
It means that the leg (or the legs) must be modeled perpendicular on the radius of
the polyprofile, see the following picture:
In Tekla Structures
In detail:
In the example above, several construction circles- and lines are modeled (check
the brown-colored construction line perpendicular to the radius).
Because of this, the polyprofile can be modeled in a correct way and whereby the
points (yellow and magenta) are positioned on the construction line, see the
following example.
Always make use of suitable construction circles- and lines in Tekla Structures to
model polyprofiles and plates in a correct way.
In Tekla Structures
In Tekla Structures you can export drawings of curved profiles and/or plates to a
DWG- or DXF-file.
For this purpose, select in Tekla Structures in the drawinglist the concerned
drawing(s), right-click and select the command Export. If desired, you can edit the
settings in the dialogbox Export Drawings, next click Export.
In the exported drawings, the arcs of the polyprofiles are displayed in real, not as
segmented lines.
Drawing in Tekla
The exported
In Tekla Structures
In Tekla Structures