The Design of Rolling Bearing Mountings

19 Rotary table of a vertical latheOperating dataInput power 100 kW; speeds up to n = 200 min –1 ;rotary table O.D. 2,000, 2,200 or 2,500 mm; maximumworkpiece diameter 2,800 mm, maximum workpieceheight 2,700 mm, maximum workpiece weight250 kN; maximum radial and axial runout 5 µm.Bearing selectionThe face plate bearings must provide a high runningaccuracy and rigidity. As the thrust load predominatesand eccentric load application causes a great tiltingmoment, a thrust ball bearing of increased precision(main dimensions 1,250 x 1,495 x 150 mm) is installed.Radial guidance is provided by an angular contactball bearing of increased precision, FAG7092MP.P5 (30° contact angle). Both bearings are preloadedagainst each other with 50 kN.The high preload guarantees a high running accuracywhile ensuring a high radial and axial moment or tiltingrigidity and keeping internal heating relatively low.By taking special measures during mounting and afterfinal grinding of the rotary table a maximum axial runoutof 5 µm is obtained.Machining tolerancesThrust ball bearing: gearing to j5Angular contact ball bearing: kingpin to j5/gearing to K6Lubrication, sealingThe bearings have circulating oil lubrication.The oil is fed directly to the various bearings throughoil feed ducts. After flowing through the bearings, theoil passes through a filter and into an oil collectingcontainer from where it returns to the bearings.The labyrinth seal prevents the oil from escaping fromthe bearings and protects them from contamination.19: Bearing arrangement of a rotary table of a vertical lathe31 FAG