Special Issue; Products for Industrial Machinery - NTN

NTN TECHNICAL REVIEW No.742006
2) Cage with improved mechanical strength
A fall impact test was performed and determined
that the resin cage excels in mechanical strength
compared to the current NTN steel plate cage type,
which has been performing well and has been
accepted favorably in the bearing market.
Test conditions
Table 2 Condition of fall impact test
Vibration acceleration (m/s 2 )
Fall cycle frequency (cpm)
9800 (fall height: 80 mm)
30
2.3 Verification of the effectiveness of antifretting
measures
The state of the backing rings after an endurance
test was investigated. As a result, we learned that our
anti-fretting measure is effective.
Test conditions
Table 3 Test condition of prevention of fretting test
Bearing speed (min -1 )
Radial load (kN)
Axial load (kN)
Run duration (h)
2125 (equivalent to train operation at 330 km/h)
54.9
6.5
7273
Test results
Test bearing
Vibration-isolating
pneumatic spring
Fig. 3 Fall impact test machine
Backing
ring
Anti-fretting
backing ring
Standard
backing ring
Fig. 5 Form of backing ring width after examination
Test results
Number of fall cycles
400000
300000
200000
100000
0
Test was suspended after 360,000 cycles
Crack occurrence after 93,000 cycles
Steel cage
Resin cage
2.4 Verification of the effectiveness of a light
contact seal
Through rotation tests, the run temperature on the
light contact seal was compared with that of a
standard seal (with spring). As a result, it was
discovered that compared with the standard seal, the
lip temperature of the light contact seal is about 20°C
lower. (The temperature measurement point was
about 2 mm directly beneath the lip on the seal sliding
section.)
Fig. 4 Test result of fall impact test
Standard seal
Light contact seal
Fig. 6 Shape of oil seal
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