bearings online
bearings online
Author :Admin | Publish Date:2013-04-09 10:11:09
Low sliding conditions are typical for the centre of raceway rolling bearings online
contacts. Using the detailed SKF model, it is possible to simulate the passage
of an indentation geometry through a heavily loaded lubricated contact and
calculate the generated deformed geometry inside the contact and the generated
pressure ripples. shows the initial “model” indentation imposed on the upper
contact surface and the centre-line profile of the isolated deformed indentation
and the generated pressure ripple at the centre of the contact calculated under
pure rolling conditions.
Increasing slightly the sliding in either direction will considerably alter
the results. Fig. 5 shows that the film thickness deformed shape exhibits a
collapse in film thickness in the frontal part of the dent. Slightly higher
pressures, however, are found in the back (trailing edge) of the dent. This
suggests that when there is a good lubricating film, the indentations are likely
to fail first fag bearings on the trailing edge of
the dent, since the pressures are higher and not from metal-to-metal contact in
the leading edge of the dent. However, if the lubrication is poor, wear and
possibly surface distress can be expected at the leading edge of the
dent.
This result is in full agreement with the experimental results carried out
at the SKF Engineering & Research Centre laboratory using full ball-bearing
tests with artificially made indentations on the raceway. Here, a zone of
surface distress (microspalls) can be observed in the trailing edge of the dent
while substantial wear occurs at the leading edge, possibly caused by the local
film collapse.
Moderate sliding conditions can be present in gear contacts. Using the
detailed SKF model with non-Newtonian fluid behaviour (increasing sliding does
not increase friction), it is possible to simulate the passage of an indentation
in the lubricated contact with these sliding conditions. Fig. 7 shows the
isolated pressure ripples, film thickness and subsurface normalized von Mises
stresses calculated for a heavily loaded contact with two different moderate
sliding bearings conditions lower smooth surface
travelling faster than upper dented surface and lower smooth surface travelling
slower than upper dented surface). It can be seen that for this moderate sliding
condition, inverting the sign of the sliding inverts the location of the maximum
pressure ripple, and thus the location of the first possible failure. This
perhaps explains some apparently contradictory experimental results reported in
the literature.
High sliding conditions are not present in the central part of bearing
raceways; however, they may be present in gear contacts. Using the detailed SKF
model with a realistic behaviour of the lubricant as a non-Newtonian fluid
(increasing sliding does not increase friction) it is possible to simulate the
passage of an indentation in the lubricated contact with these sliding koyo bearings conditions as it moves inside the
contact.shows the isolated pressure and film thickness ripples as a function of
time for one high sliding condition the smooth lower surface moving faster than
the upper dented surface).
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35BD219T12DDU
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