Selecting an appropriate quenching medium
is particularly important. It determines the bearing microstructure and
properties after quenching. Quenching medium usually has solid, liquid and gas
three forms.
Deep groove ball bearings in heat treatment
furnace heated to fully austenitic, for obtaining the required organization and
performance, it need for a quenching treatment. Workpiece after cooling to
obtain martensite organizations, its cooling rate must be greater than the
critical cooling rate, but too cool and too fast will make volume shrinkage and
microstructure transformation violent, caused a great deal of stress. Thus
conditions for martensitic "f" should enable the cooling rate as low
as possible.
NTN bearings after correct repairing are
the same performance with new bearings. The precision parameter such as its
clearance can meet the requirements of new bearings. It is important to
understand and identify damage degree to choose the correct rehabilitation
program. For example, surface finishing treatment can clear some minor damage,
but could not clear the real fatigue and the debris or wear caused by
depression. Therefore, if only for the NTN bearing surface finishing treatment,
generally it is not suitable for serious injury deep groove ball bearings. And
if fully repair remanufacturing technology, the fatigue of bearing layer is
completely clear, replace the rolling elements, also cage being undertaken a
comprehensive consolidation so that bearings can meet the performance
requirements of a new bearing.
Once the deep groove ball bearings injure,
they must go through a very rigorous testing procedures to determine whether
the injury NTN bearings can be repaired. Bearings must be fully cleaned, and
then a very rigorous and comprehensive testing. The first is to detect whether
the bearing damage, such as cracks, spalling and thermal discoloration, bearing
with these injuries are likely beyond repair and must be scrapped.
Raceway surface of deep groove ball
bearings, due to contacting with the roller elements, its running track is the
dark side, track attached to the roller surface is within the exception, which
may be able to tell the load conditions, so in removing the NTN bearing cases,
pay strict attention and observe of raceway surface running track, you will
learn the it bears only radial load, subjected to an axial load, tolerance for
moment loads, or extreme inequality of rigid on the bearing box.
1, appropriate clearance of NTN bearing, too
large will impact, too small will be poor lubrication, may be burnt.
2, improve lubrication quality and control
oil pressure, temperature and flow, strengthening the oil filter.
3, geometry and surface quality of NTN
bearings and axle should be strictly guaranteed.
4, adopted the fuel and lubricating oil in
accordance with the demarcation.
5, take control of engine temperature,
overheating or in cold case work is negative. In cold weather, diesel engine
should warm up before starting, scroll with the hand crankshaft oil into the
friction surface.
No comments:
Post a Comment