**6. Application research**

84 Performance Evaluation of Bearings

**Figure 29.** Scheme of Machine Tool Headstock Control

## **6.1. The new headstock construction for turning machine tools**

TRENS a. s. Trenčín, is a Slovak manufacturer of machine tools (mainly lathes) and offers a new generation of lathes implementing various technological advances in design, production, and control systems, [22]. The Department of Production Engineering has been asked to design an accurate running spindle for the SBL 500 CNC lathe (Figures 31 -33), [23]. All construction data and results of measurements were obtained from the producer. Table 2. shows the calculated (Spindle Headstock Version 2.8) values [23] of the optimized design. Figure 34 shows the comparison between the original and optimized designs.

**Unit Value Notice [%]** 

18,45

9,79 6,16 2,49 53,0 33,5 13,5

Total axial stiffness Ca [N/μm] 372 Total radial stiffness Cr [N/μm] 351

Distance between supports L [mm] 327

**Figure 34.** Headstock of SBL 500, Original design, Optimized design

natural frequencies (COSMOS).The results were in good compliance [24].

The most valuable advantage of this system is the possibility of calculating dynamic stiffness at different revolving frequencies of the spindle. The given mathematical model was verified on a number of spindles with programs which enabled the calculation of

The verified spindle, which complied with research findings, was reduced to a three discrete parts. The dynamic mathematical model described above was used to calculate the natural frequencies and dynamic deflections. Table 3 compares calculated and experimental

[μm] [μm] [μm] [μm]

Limited frequency of rotation nc [min-1] 2695 unfit Life-time Th [hour ] 5175 unfit

Total spindle displacement yr displacement forces resulting from - the bending moments yMo - the bearing compliance yL


**6.2. Dynamic analysis** 

values.

**Table 2.** Calculated values of optimized design

**Figure 31.** CNC Lathe SBL 500

**Figure 32.** Original design of SBL 500

**Figure 33.** Optimized design of SBL 500

Radial Ball Bearings with Angular Contact in Machine Tools 87


**Table 2.** Calculated values of optimized design

**Figure 31.** CNC Lathe SBL 500

**Figure 32.** Original design of SBL 500

**Figure 33.** Optimized design of SBL 500
