TPT July 2013

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Bending, end forming and swaging
July 2013 91
Bending large radii accurately
SCHWARZE-Robitec has further
developed its freeform bending concept
for all-electric tube bending machines.
The technology allows the precise
creation of large bending radii and
variable radius paths on tubes and
profiles.
A high level of repeat accuracy
is achieved, even with new, higher-
strength materials. At the same time,
the system supports the combination
of freeform and mandrel bending in one
clamping operation and is therefore
particularly suitable for users from the
automotive and agricultural machinery
industries, as well as for stair lift and
furniture manufacturers.
The requirements for freeform
bent tubes and profiles are growing:
increasingly complex bending paths
and the reshaping of higher-strength
materials demand improved bending
machines and software concepts. The
current renaissance in hydroforming is
also reinforcing this trend. In order to
equip the tube and profile processing
industries for these and future market
requirements, Schwarze-Robitec has
improved the freeform bending concept
for its all-electric tube bending machines.
The manufacture of large bending radii
of size 6xD is more precise with this
technology.
“At the same time, the production
process is accelerated by up to five
times, or even ten times in individual
cases,” said JürgenKorte, plant manager
of Schwarze-Robitec. “This is because
the revised concept allows very high
bending speeds and the setup times
previously required are appreciably
reduced due to the increased precision.”
In the freeform process, the bending
radii are created not with fixed tools, but
by means of independently mounted
rollers. The desired bending radius is
defined by the feed angle of a reshaping
roller. Very large radii and complex
radius paths can be created with
bending radii of varying sizes.
The technology is used in all of
the all-electric bending machines in
the CNC 40 E TB MR to CNC 160 E
TB MR series. Using robust bending
heads, even high-strength materials
can be manipulated into the desired
shape with no problem by means of the
freeform process.
“We have recently delivered an all-
electric tube bending machine with this
new technology to Mexico, to one of the
world’s largest automotive suppliers,” Mr
Korte said. The machine, which has been
expanded to be fully automatic – including
loading unit for machine feed, measuring
system and handling robot for onward
transport of the bent parts – ensures fully
automated and therefore very fast and
economic bending processes.
Schwarze-Robitec GmbH – Germany
Email:
Website:
More stable pipelines
for oil, gas and water
LARGE pipes, such as those used to
construct pipelines, are either welded
together as spirals or with a longitudinal
seam. In cooperation with Swiss
company Maurer Magnetic, the plant
and machinery manufacturer Schuler
has now developed a process that can
demagnetise large pipes during their
production. This improves the quality
of the welds, which in turn enables
pipelines to withstand greater pressures.
Magnetisation results from the
bending, machining and rolling of steel
sheets, and also from the submerged
welding of the spiral or longitudinal seam.
When pipe ends are welded together on-
site, the arc can be deflected if there is
too much residual magnetism, reducing
the load-bearing capacity of the weld.
This is not the case with demagnetised
pipes. Recent research results also
indicate an increased incidence of
corrosion on magnetised pipes.
“Pipelines are exposed to extreme
loads, as they often have to span
hundreds of kilometres of inhospitable
territory with extreme temperatures,”
explained managing director Jochen
Früh. At the same time, the pressure
inside the pipes is constantly being
raised in order to extend the distances of
the transported materials – such as oil,
gas or drinking water – and to bridge the
growing distances between individual
extraction areas.
In the process developed by Maurer
Magnetic and Schuler, the welded pipes
are pushed through an electromagnetic
coil and demagnetised. “There is no
delay at all in production,” said Marek
Rohner, head of technology at Maurer
Magnetic. “We have therefore patented
the process.”
Tests at Schuler’s site in Weingarten,
Germany, have shown that the method
is suitable for spirally welded pipes
with a wall thickness of up to 30mm
and a diameter of 1,422 to 3,500mm.
Pipes with longitudinal welds can
have diameters of around 2,500mm
and a wall thickness of 20 to 40mm.
Maurer Magnetic’s experts also use
their patented Maurer Degaussing
Technology for the process. The large
pipes are completely demagnetised by
an alternating magnetic field, which can
reach a field strength of up to 80kA/m in
the high-performance coils.
Schuler supplies machines, produc-
tion lines, dies, process know-how and
services for the entire metalworking
industry. Customers include car manu-
facturers and their suppliers, as well as
companies in the forging, household
equipment, packaging, energy and
electrical industries. The company
also supplies systems solutions for the
aerospace and railway industries.
Since the year 2000, Maurer Magnetic
has entered new markets with its newly
developed and patented technologies
in the field of magnetising and
demagnetising applications.
Schuler AG – Germany
Fax: +49 7161 66 907
Website:
Maurer Magnetic – Switzerland
Email:
Website: