**4.2. Recommendation for improvements in construction**

The recommendations from the point of view of temperature optimisation for the DB 24 SHS boring machine are based on the results of the analysis undertaken. From the perspective of temperature, it can be seen that a change in bearing node arrangement to individual spindle supports from DB to DT would be advantageous, Figure 15.

**Figure 15.** Model of the spindle

Results for spindle with arrangement DB - DB.


*Working conditions* 

72 Performance Evaluation of Bearings

where

where

2 2

0 00 .sin . . .sin . 2.

0 00 .cos . . .cos . 2.

 

> 

*mI A I A al B t t l t t t*

*mA I I A bl D t t l t t t*

<sup>0</sup> *<sup>t</sup>* 

2/3 2/3 8/3 *F zc* . . .sin 

<sup>5</sup> 10 . 1,25 . *<sup>w</sup> c d*

In the twin bearings FAG B 7016 C.TPA.P4.UL with DB arrangement, at a temperature gradient of 10 C, and with bearing distance Bm = 29 mm, the preload will increase by 13,32 N.

Conversely, if the distance of the bearing in O arrangement is long (Figure 13b), the dilatations in the axial direction prevail and cause a decrease in the value of the preload.

In the twin bearings FAG B 7016 C.TPA.P4.UL with DB arrangement, at a temperature

In DB arrangement, the main goal of temperature optimization is dependant on the determination of the optimum distance between the bearings at which a change in the

By substituting equations (42) and (43) into (46), the optimal bearing separation distance

Figure 14 shows the change of optimal bearing distance at various values of the temperature

 0 0 cos . 2. <sup>1</sup> . . sin sin *I A*

*lt t t*

*t t*

*I A*

 

*l ab* (41)

(42)

(43)

*l l* (44)

(33)

<sup>0</sup> *<sup>t</sup> l l* (46)

(47)

(45)

*t*

2 *t*

2 *t*

and preload change in accordance with [18] will be

gradient of 10C , the preload will be decreased by 5,88 N.

preload at the given temperature gradient would be minimal.

from the point of view of temperature can be deduced from:

*mopt m*

*B D*

In accordance with Figure 13 the condition

gradient for the analysed SBS, Figure 11.

must be satisfied.

The magnitude of deformation will be



Radial Ball Bearings with Angular Contact in Machine Tools 75

**Figure 16.** Entering the input data

2. The ability to select the most appropriate bearing or bearing node arrangements (Figure 17, Figure 18, Figure 19). Data about selected bearings can be ganed from extensive databases according to the users requirements within the bearing inner diameter range: angular contact ball bearings, type 7 10..150 mm single row cylindrical roller bearings, type N 50..120 mm full cylindrical roller bearings, type NN 30..440 mm axial angular contact bar, type 2344 25..380 mm thrust ball bearings, single direction, type 51 10..360 mm thrust ball bearings, double direction, type 52 10..190 mm deep groove ball bearings, type 6 3..360 mm;

**Figure 17.** Selection of the bearing arrangement and type of bearings

In comparison with the original bearing node arrangement, the radial stiffness of the rearranged spindle-bearing system will drop slightly, but its axial stiffness will increase. The advantage of the reconfigured SBS is that at real mean values of temperature gradient, the SBS stiffness will be almost fixed.
