RKB Developments in Wind Turbine Rolling Bearings0 pages

26 Power Transmission World - november 2011
FEATURE FOCUS
Alberto Barili*
The RKB Group, the Swiss
premium-class bearing manufacturer,
is daily committed to conceiving and
developing leading-edge solutions for
the wind energy industry. This implies
important investments in innovation
and research, with particular
attention to design optimization,
heat and thermochemical
treatments, and manufacturing
technology as a whole.
Developments in wind
turbine rolling bearings
The sources of renewable energy
are also called sources of
alternative energy as the energy
produced in this way is the
main alternative for energy resulting
from exhaustible sources.
In the economy of this century, renewable
energies are holding a prominent position. In
particular, the wind energy has recently experienced
remarkable spreading, in virtue of its
inexhaustibleness and cleanliness. Of course
wind energy plants may also have undesirable
effects such as noise, occupancy of large areas
of open space and visual impact on landscape.
However, the positive aspects of this type of application
(e.g. the non-introduction of several
million tons of pollutants and greenhouse gases
into Earth’s atmosphere) widely compensate
for all possible drawbacks.
Over the last years almost all wind industry
manufacturers have been focusing on producing
innovative design turbines able to operate
even at low wind speeds (3 m/s) and generand
developed specific software tools (MTDS,
RRLC, NON-HERTZ etc.) to determine and
study bearing most crucial parameters, such
as rating life, force and stress distribution, misalignments,
recommended fits and lubrication,
Hertzian and non-Hertzian loads and so on.
These PC programs are extremely useful when
designing the complex applications of the wind
energy sector since they make possible to properly
and simultaneously consider all the factors
affecting the behavior of the bearings mounted
in the assembly. Naturally, all calculations are
performed according the most advanced and
recent international standards. As is evident, the
service life of a wind turbine depends also on
the life of the bearings that have been installed.
For this reason the operation of wind turbine
bearings should be efficient and reliable even
under unfavorable environmental conditions.
The life of a wind turbine is normally guaranteed
for almost twenty years. However, a general
inspection procedure is advisable every four
years in order to assess the conditions of gears
ate more and more power. The unceasing advancements
of blades, nacelles and speed multiplicators
have allowed to collect wind energy
at higher and higher altitudes, also thanks to
the improved capacity of the tower to support
the weight of the entire system.
“The Alternative Power”
In an increasingly competitive sector, the RKB
Group, with Executive Headquarters and Technological
Center in Balerna (Switzerland),
has decided heavy investments in Research
& Development to efficiently satisfy the requirements
of the alternative energy industry,
which is becoming more and more demanding
in terms of performance and cost-effectiveness.
In order to optimize wind energy applications,
RKB engineers rely on Catia software system
to create the 3D models of the assembly and
on Ansys Workbench Platform to evaluate
the behavior of the bearing by means of the
FEM (Finite Element Method) analysis. Besides,
the RKB Group has purposely designed
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