The Design of Rolling Bearing Mountings

16 Bore grinding spindleOperating dataInput power 1.3 kW; spindle speed 16,000 min –1 .The spindle is radially loaded by the grinding pressure.The load depends on grinding wheel quality, feed anddepth of cut.Bearing selectionDue to the high speeds required during bore grinding,the spindle speeds must also be high. Sufficient rigidityand accurate guidance, especially in axial direction, arealso required. The demands for high speed and high rigiditycan be met with spindle bearings. As the spindlerequires primarily a high radial rigidity, it is advisableto provide bearings with a contact angle of 15° (designC).At the work end and at the drive end there is one spindlebearing set FAG B7206C.T.P4S.DTL in tandemarrangement each. The load is equally shared by theseO arranged tandem bearing pairs. For this purpose thespacer rings must be identical in width and also flushground.The bearings are lightly preloaded by a coil spring forclearance-free operation under all operating conditions.The preload increases the rigidity of the bearingarrangement. It is, however, limited by the permissiblebearing temperature and varies between 300 and500 N depending on the spindle application.The spindle diameter, which determines the bearingsize, is based on the required rigidity.Lubrication, sealingGrease lubrication for high-speed bearings (FAG rollingbearing grease Arcanol L74V). The bearings arelubricated for life during mounting and therefore norelubrication is required.The high-speed bearings require the use of non-rubbingseals, in this case labyrinth seals.Machining tolerancesSeat Diameter Cylindricity tolerance Axial runout tolerancetolerance (DIN ISO 1101) of abutment shoulderShaft js3 IT0/2 IT0Housing (drive end) +2/+6 µm IT1/2 IT1Housing (work end) –1/+3 µm IT1/2 IT1Drive endWork end16: Bearing arrangement of a bore grinding spindleFAG 28