Note: Descriptions are shown in the official language in which they were submitted.
CA 02798350 2012-11-05
Bending Machine for Creating Bends to the Left and Right
The invention relates to a device and a method for bending tubes in tube
bending machines, where the
tubes to be bent are heated inductively at the bending location. The tubes are
often thick-walled tubes
with wall thicknesses of 3 to 120 mm and with large diameters of 50 to 1060 mm
and weights of several
tons; Correspondingly large and heavy are the tube bending machines that are
developed for this
purpose. These can typically realize bending radii of 0.1 to 10 meters.
For each bending procedure, the straight end of the tube to be bent must be
clamped in a feeding
carriage while a so-called bending lock is attached to that end that is to be
bent. An annular device for
inductive heating, typically also referred to as an induction ring is located
between the bending lock and
the feeding carriage.
Due to the effective large forces that need to be taken up, bending locks
often have a very bulky design
and take up a lot of space. DE 10 2007 022 004 A, for example, describes a
relevant device. In this case,
the bending lock is mounted on a bending arm, and the bending arm can rotate
around a vertical
rotational axis.
Often, tubes must be bent several times in different directions. This allows
for achieving complex
curvatures or, for example, S-shaped or serpentine tube geometries that can be
manufactured very
precisely under controlled conditions with such tube bending machines, which
otherwise would only be
possible at the future place of installation by using pipe fittings and welds
and with limitations in the
attainable precision.
Tube bending machines of the prior art can perform such bending steps in
succession to some degree,
however, if the desired pipe shape requires that the bending direction changes
between two successive
bending steps, significant installation work is required between the bending
steps. In other words, the
entire bending lock together with the bending arm must be disassembled and re-
assembled each time
and aligned at the mirror-inverted side of the tube to achieve this purpose.
Or, the tube to be bent must
be removed from a left-bending machine and fed into an additional machine, a
right-bending machine.
This causes geometric inaccuracies that can be eliminated only with
significant effort.
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CA 02798350 2012-11-05
For example, DE 25 13 561 A 1 presents a machine with a small and a large
bending arm, rotating one
time to the right and one time to the left. To be able to utilize this system
for spatial bends, the tube must
be removed from the right-rotating side of the machine and re-clamped and
positioned in the left-
rotating side. This is associated with significant time expenditure and leads
to inaccuracies.
DE 100 60 605 A 1 presents left- and right-rotating bending heads, however,
due the fact that the
bending heads are located one above the other, the end of the tube must travel
all the way down in order
to get to the second bending head.
Since both of the tubes to be bent and the equipment component of the bending
lock and the bending
arm are very heavy, significant effort and care must be exercised when
operating the lifting devices in
order to avoid any damage during the installation work and to prevent
uncontrolled changes in the
position of the tube to be bent.
Such installation work can take several hours and restrict the throughput due
to the bending steps at the
bending machines.
It is, therefore, the objective of the invention to provide an economic
method, where such installation
work can be reduced to a minimum, thereby significantly increasing the
throughput of such bending
machines when used for making multiple bends.
The invention achieves this objective with a device for bending tubes of large
diameters, in different
directions, whereby
- in this bending device a tube is guided in the axial direction through an
inductive heating device
that surrounds this tube in annular fashion,
- the tube is clamped at the end that is to be bent by a bending lock,
- at least one bending arm that is supported in a rotating fashion around its
vertical rotational axis
is located at the part of the device for bending and is situated in the
feeding direction of the tube,
- the bending lock is connected indirectly to the bending arm,
- the bending lock exhibits a force transfer device between the take-up device
for tubes and the
bending arm,
- the force transfer device is connected to the bending arm in an adjustable
manner such that the
distances between the center axis of the take-up device for tubes and the
vertical rotational axis
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can be selected between a minimum and a maximum distance, which allows for
setting a range
between a maximum and minimum bending radius,
- the device exhibits at least one additional bending lock with one additional
bending arm, a take-
up device for tubes and a force transfer device for bending forces from the
take-up device to the
additional bending arm,
whereby the direction of rotation of the additional bending arm is opposite to
the direction of
rotation of the first bending arm, and
each of the two bending arms can be moved parallel to each other and
perpendicular to the
feeding direction of the tubes to be bent.
The result of using 2 movable bending arms with bending locks is that for
right rotations and for left
rotations the respective vertical rotational axes of either the one or the
other bending lock is used, while
the respective other bending lock which is not needed is moved out of the
pivoting area. Thus, the
expensive installation work is not needed at all.
The invention accomplishes this objective by a method for bending tubes of
large diameters that is
matched to the device, by
- clamping the tube in a first bending lock that is connected to a first
bending arm that can be
rotated around a first rotational axis,
- a second bending lock being moved away from the pivoting area of the tube
against the
rotational direction and in the perpendicular direction to the feeding
direction of the tube to be
bent,
- then bending a first section of the tube by advancing the tube,
- declamping the tube from the first bending lock while securing the tube,
- moving the first bending lock from the pivoting area of the tube in
perpendicular direction to the
feeding direction of the tube to be bent,
- moving the second bending lock into the pivoting area of the tube,
- clamping the tube to be bent in the second bending lock,
- then bending a second section of the tube by advancing the tube.
During the change of the bending direction, the tube remains in an absolutely
fixed position through
being clamped in the feeding carriage.
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In additional embodiments of the method according to the invention tube
movements are carried out
between the individual bending steps. In these steps, the tube may be rotated
around the center axis of
the tube or advanced longitudinally. In this manner, numerous bending steps
can be carried out in
succession.
The invention will be explained in greater detail below based on Figures .1 to
4e. Figure 1 shows an
isometric drawing of a double bending machine; Figure 2 shows a top view. Fig.
3 shows a front view.
Figures 4a to 4e show a top view of the individual procedures during multiple
bending of a tube.
Figures 1 to 3 show such a double bending machine 1 with the two bending arms
2 and 3 and the
bending locks 4 and 5. The tube to be bent (not shown) is located on the
feeding carriage 6 and is
pushed through the induction ring 7, wherein either the bending lock 4 or the
bending lock 5 grips the
tube and bends it around the rotational axis 8 or the rotational axis 9.
Fig. 4 shows the steps for an S-shaped bend of a tube 10.
Fig. 4a shows the initial state. The tube 10 is located in the feeding
carriage 6; its front tube end 11 is
pushed through the induction ring 7 and is held by the bending lock 5. The
bending arm 3 is thus
positioned such that the desired bending radius 12 can be set and the bending
arm 2 is moved out of the
pivoting area.
Fig. 4b shows the end of the first bending step, in this case a 135-degree
bend.
Fig. 4c shows that the bending lock 5 has been removed and the bending arm 3
has been moved away
and that an advance by the feed length 13 has occurred.
Fig. 4d shows that the bending arm 2 has been positioned such that the bending
radius 14 can be set and
that the bending lock 4 secures the tube 10. The bending arm 3 remains in its
position out of the pivoting
area.
Fig. 4e shows the result of the second bending procedure, in this case a 135-
degree bend that is exactly
opposite to the first bend.
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It is also apparent that many other spatial bending steps can be carried out
in this manner without the
need to disassemble the workpiece or one of the bending arms. for this
purpose, which saves
considerable set-up time compared to the prior art and thus increases the
turnover of the machine in a
positive economical manner.
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List of Reference Characters
1 Double bending machine
2 Bending arm A
3 Bending arm B
4 Bending lock A
Bending lock B
6 Feeding carriage
7 Induction ring
8 Rotational axis A
9 Rotational axis B
Tube
11 Front end of the tube
12 Bending radius A
13 Feed length
14 Bending radius B
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