Timken Super Precision Bearings for Machine Tool Applications

Simple Mounting
The evolution of two single-row bearing arrangements for spindles,
discussed below, is directly related to the speed requirements and,
consequently, the lubrication modes (see page 56).
TS and TSF Arrangement
The spindle is supported by one bearing at the nose position and a
second one at the tail position. This layout offers the advantage of being
a simple isostatic design that allows easy machining of adjacent parts.
The mounting and setting procedures can be achieved without any
specific tooling.
Static stiffness calculations of the spindle-bearing system allow
the optimum bearing spread to be determined precisely for each
mounting, as a function of the overhung value of the spindle nose.
A good approximation, however, is to consider that the distance
between bearing centers should be of two and a half to three times
ENGINEERING
the spindle nose diameter. This represents an optimum value not
only for stiffness, but also for thermal equilibrium.
Figure 75 represents the simplest layout of a two single-row bearing
concept. The view above the centerline shows flanged cups (Type
TSF) allowing a through-bore machining concept for the housing,
which offers increased accuracy with no need for cup backing
shoulders. The arrangement shown below the centerline uses two
single-row bearings (Type TS).
The bearings are adjusted by means of a ground spacer locked by a
precision nut. Lubrication is often achieved by oil circulation, which
enters through radial oil inlets or special high-speed grease.
As shown below, the next evolution of this arrangement consists
of improving the lubrication system by using appropriate jets for oil
inlets and cooling (Figure 76 and Figure 77).
A
2.5 to 3 times d
(theoretical)
d
Fig. 75. Simple mounting with a pair of TS or TSF bearings.
Fig. 76. Simple paired TS mounting with oil inlet at the small end of
the rollers.
Fig. 77. Simple paired TS mounting with oil jets at both ends of the
rollers for inlet and cooling.
TIMKEN MACHINE TOOL CATALOG 95