WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 5/2017

High-performance bearings for
automation technology and robotics
MACHINE ELEMENTS
Bearing supports in robotics and precision gearbox
manufacturing share the same need for high load
carrying capacities and high rigidity in minimal design
envelopes. Cylinder roller-based bearings provide the
solution.
The angular contact ball bearings from ISO series 718 are used
specifically in the output side of high-precision planetary
gearboxes in order to significantly reduce the design envelope
required. At the same time, however, these bearings also have to
transfer high combined loads that are made up of axial and radial
forces together with tilting moments. They are also a component
used in robot hand axes, where the focus is on the low weight of
the overall construction and the large hollow shaft, which can
only be implemented with very small bearing cross-sections. The
deformations and displacements to which the angular contact
ball bearings are subjected as a result of these forces and moments
are the biggest limiting factors on the path towards even
greater precision.
Line contact offers better tilting rigidity and less
deflection
Schaeffler offers a technologically and economically attractive solution
for increasing rigidity and load carrying capacity in an identical
design envelope with its INA angular contact roller bearings.
These are rolling bearings with cylindrical rollers and raceways that
are arranged at an angle to the bearing axis. The line contact of the
cylindrical rollers ensures an outstandingly high level of rigidity, a
noticeably high load carrying capacity and minimal deflections. A
simple comparison demonstrates this clearly: A ball with a diameter
of 10 mm that is supporting a nominal force of 1000 N causes a
deflection of 40 µm, while a cylindrical roller of the same diameter
reduces the deflection to 8 µm and thereby offers a 5-fold increase
in rigidity.
SGL series – precise and rigid
The angular contact roller bearings from Schaeffler, are available
in 2 designs: SGL and AXS. The precisely ground, triangular ring
cross-sections of the SGL bearings together with the linear contact
of the cylindrical rollers allow very precise, rigid bearing supports
with a high load carrying capacity to be achieved. The cage, which
is made from wear-resistant plastic, is located between the bear-
WORLD OF INDUSTRIES – MOTION, DRIVE & AUTOMATION 5/2017