Page 221 - Rollingbearings

Bearing interfaces
Operating temperature Table 1

and speed Seat tolerances for standard conditions
Dimensional Total radial run- Total axial run- Ra
tolerance out tolerance out tolerance

Shaft g6� IT5/2 IT5 1,6 µm
Housing P7� IT6/2 IT6 3,2 µm
Experience from similar applications is broad and a bearing operating
temperature between 70 to 80 °C (160 to 175 °F) can be assumed.
The screen charge is at ambient temperature and there are no
other external sources generating heat. The speed is < 50% of the
limiting speed. Although the load ratio C/P < 10, no detailed thermal
analysis is required.
The actual operating temperature should be checked on the real
machine. Fig. 3
The bearing frictional losses are 1 900 W per bearing, calculated Aligning the bearing centrally with the vibrating screen frame
with the SKF Bearing Calculator (skf.com/bearingcalculator).
A ` A
A = A´
Bearing interfaces

The radial load turns in phase with the rotating inner ring, while the
outer ring stands still. Therefore, the inner ring has a stationary load
condition and the outer ring a rotating load condition. An interfer-
ence it is needed between the outer ring and the housing. A loose it
can be used between the inner ring and the shaft.
The standard it recommendations are listed in table 1.
There are reasons for choosing dimensional tolerances other than
the standard its:
Fig. 4
• Choose f6� for easy axial displacement of the inner ring. To Symmetrical housing prevents raceway deformation
reduce the risk of fretting corrosion, consider hardening the shaft
seat.
• Select P6� (tighter tolerances) to improve outer ring support and
bearing service life. Asymmetrical housing Symmetrical housing

Additional recommendations

The following additional factors are recommended:

• The bearing centre should be aligned with the frame centre of the
vibrating screen (ig. 3).
• The housing wall thickness should be greater than 40% of the
bearing width. Raceway proile before and after mounting
• Design the housing to be as symmetrical as possible, so it has the
same thickness on both sides of the vibrating screen frame, in
order to avoid housing deformation (ig. 4).
• Machine threads in the housing to make it easier when dismount- C.1 Vibrating screen
ing the housing from the screen body and the bearing of the hous-
ing by the use of bolts (ig. 5 and ig. 6, page 220).

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