TPT September 2013

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September 2013 135
Article
Schwarze-Robitec GmbH
Schwarze-Robitec GmbH – Germany
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The automatic, CNC-controlled machines are also suited
to complex tube systems with several bends or large batch
sizes. “Compared with the induction bending processes,
our cold bending process offers huge time savings in the
production process,” Schwarze-Robitec plant manager Jürgen
Korte explains. “Whereas hot shaping of these work pieces
takes around eight hours, our customers require an average
of only six minutes for one bend.” Depending on the specific
application, Schwarze-Robitec offers the machines from its
heavy duty machine series for various diameters and wall
thicknesses up to 610 x 21.4mm. The machines are available
in semi-automatic design with SR control and in automatic
design with CNC control. All machines can be equipped
with a tube magazine and tube feed and enlarged up to fully
automatic bending cells.
Economical production of
boiler tubes
Very different but similarly exacting requirements now also
exist for boiler tubes and tube serpentines in power plant
construction. The production of smaller boilers with greater
capacity, for example, requires the use of extremely tightly
bent tubes. Depending on the tube diameter, it is not
uncommon for the required minimum bending radius to be
1xD (sometimes under 1xD). The semi-automatic booster
bending machines and automatic CNC pressure bending
machines from Schwarze-Robitec are designed precisely for
these requirements. The unique cold-bending process from
Schwarze-Robitec offers utmost precision and surpasses the
tolerance requirements for wall thinning and out-of-roundness
of European standard EN 12952, American Society of
Mechanical Engineers ASME B31.1 and all other international
standards.
The CNC-controlled booster bending machines are also
equipped with a tube positioning device, which facilitates fully
automatic bending of tube systems. For efficient processing of
very large and complex tube serpentines, Schwarze-Robitec
offer the CNC Twin series machines: this machine series,
which is available in three different sizes up to diameter 88.9
x 11mm, uses two vertically and horizontally movable bending
heads (1x left-bending, 1x right-bending), which alternately
bend the tube clockwise and anticlockwise.
Consequently, the tube serpentine does not need turning after
each bend, which ensures quick and economical production
processes and the manufacture of large leg lengths. “Of
course, our machines also guarantee the processing of high-
strength materials, for example, such as high temperature
steel alloy T91,” managing director Bert Zorn adds. Moreover,
they are able to produce different bending radii within one
tube system. Furthermore, adding a Terminal End Bender to
the machine is easily possible.
Precise processing of complex
tube walls
Schwarze-Robitec also offers a specialised bending
technology for the bending of entire membrane tube walls,
which is common in the construction of modern boilers and
power plants: the FL machine series processes tube walls
with a maximum width of 3,600mm and a length of 25,000mm
or more, quickly and accurately by means of the compression
bending process. The machines are equipped with a modern
CNC control, which also takes into account the springback
when bending the membrane tube wall.
Only recently, the bending specialist delivered one of the
world’s largest membrane tube wall bending machines to an
Indian customer. With this machine, customers are able to
bend tube walls precisely in particularly large dimensions.
The users secure considerably reduced costs and production
times as well as lower installation costs. Equally, this machine
offers the option of diagonal bending. “Overall, we have
been developing and producing tube cold bending machines
designed especially for the specific requirements of power
plant construction for over 45 years,” Schwarze-Robitec
managing director Bert Zorn summarises. “Every machine
is a customised solution, which we adapt precisely to the
individual production needs of the customer.”
The CNC 100 DB Twin booster bending machine from Schwarze-
Robitec reliably bends even high-strength materials with a bending
radius under 1xD
The FL 3600 tube bending machine from Schwarze-Robitec
guarantees the quick and economical production of huge
membrane tube walls