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2007
FQM™: Danieli’s 3-roll pass retained mandrel
mill for high quality seamless tube production
By Mr E Cernuschi, Danieli Centro Tube, Italy
1. Background
The activities of Danieli in the field of the pipe plant market dates
back to the early 1980s, through involvement as a sub-supplier or
partner in important contracts for both seamless and welded pipe
projects. However, the involvement of Danieli remained marginal
until 2003, when the decision was taken to enter new markets.
This move was intended to both increase revenues and serve
customers better with a more global range of products. In particular,
the decision to begin the design and manufacture of seamless pipe
plants has been confirmed by the considerable growth in the energy
sector, due to increased global oil and gas consumption.
Together with the know-how and technology exclusively supplied by
Kocks for finish rolling, Danieli Centro Tube can provide the whole
technical package – including mechanical, electrical, automation,
and reheating systems. This leads to advantages such as smoother
coordination through all stages of the project.
Danieli Centro Tube provides the process technology and
mechanical design of the machines; Danieli Centro Combustion
provides heating systems; Danieli Automation develops process
automation and related electrical systems; and Danieli Centro
Maskin contributes with auxiliary machines.
As a result, three large projects are already in progress, while a
fourth order has recently been awarded.
2. Seamless tube production overview
Over the last 30 years, the state-of-the-art Retained Mandrel Mill
(RMM) process has been the most advantageous method for
high quality seamless tube manufacture. It holds an extremely
competitive position when compared with other processes in
corresponding conditions.
A universal process, it is highly suitable for all pipe dimensions and
steels grades. RMM is also a flexible approach, suitable for high
and low tonnage production, with an exceptional capacity to meet
a variety of market requirements. With comparatively low cost
investment, it provides additional capacity in producing high quality
products, both for size tolerances and surface quality.
The first generation of the retained mandrel mill, based on 2-roll
pass design type technology, is now operating worldwide under
the highest possible performance. Meanwhile, the new 3-roll pass
design version has made a steady entrance into the market. FQM™
(Fine Quality Mill) is Danieli’s enhanced and progressively modified
version of the first generation.
3. FQM™ at a glance – overview
The Danieli FQM™ offers process technology able to produce
seamless pipes with high quality features (close wall thickness
tolerances and very smooth surfaces), at low production cost.
The FQM process is based on the continuous rolling principle, with
rolling passes on a cylindrical mandrel that moves at a constant
controlled speed during the whole rolling phase. Rolling mandrel
speed is calculated according to the deformation scheme and is
less than the outlet tube speed from the first stand.
The material therefore moves faster than the mandrel; consequently
friction forces between the material and the mandrel are in the
rolling direction versus a longitudinal material flow. The elimination
of the transversal metal flow in the roll gap direction and the inline
extraction of the tube from the mandrel (immediately after rolling),
allow the use of a very close pass design.
Moreover, the process offers a high degree of production flexibility,
versatility and efficiency fully supported by process control features
like automatic gap control and wall thickness in-line measurements.
›
Figure 2
:
With a 3-roll pass design, the Danieli FQM™ process is based on the
continuous rolling principle
fi
Figure 1
:
Danieli’s FQM™ (Fine Quality Mill) can produce superior quality
seamless pipes