grinding wheel constructions are developed from far cheaper grains that may be successfully used in conventional internal cylindrical grinders. For this purpose a theoretical and experimental basis of internal cylindrical traverse grinding using zone-diversified structure grinding wheels, made from conventional abrasives on basis of Al O were 2 3 developed. Such grinding wheels are divided into two functional zones (rough and finish grinding zones), with characteristic and different construction [10-12].

the extreme positions of the table feed. The complete system was mounted on the top part of the basis in order to maintain unchanged dressing kinematics with different values of the conic chamfer.

### 3. EXPERIMENTAL INVESTIGATIONS

Using the developed device, tests were carried out whose aim was to determine the most advantageous parameters of the conic chamfer shaped in the dressing cut on the active surface of grinding wheels with zone- diversified structure.

### 2. DEVICE FOR PRECISION SHAPING MACRO-GEOMETRY OF THE GRINDING WHEEL

##### 3.1. Methodology of experimental investigations

During the realized tests value of the conic chamfer was adjusted to the size of the working c contact a in such a way so as to make the conic part e of the abrasive tool covered the whole machining allowance for the machining. The second parameter to which angle belonged was the chamfer width b. c With the same working contact, a change of the chamfer width caused considerable angle differences (Fig. 2), whose values during the tests were = 0.38-1.15°. c

Effective realization of the process of internal cylindrical traverse grinding with zone-diversified structure grinding wheels is possible if precise shaping of the used grinding wheel active surface macro- geometry is provided. Both the construction of conventional grinders and CNC allows for changing the angular location of the grinding wheel spindle, thanks to which it is possible to make conic chamfer on the grinding wheel active surface. Such changes in the shaping machine settings are, however, labor- intensive and therefore unprofitable if they need to be performed with each dressing procedure. On top of that they don’t provide sufficient precision of angular positioning. In order to make it possible to quickly shape the conic chamfer with given geometrical parameters on the GWAS, it was necessary to construct special device. The most important element of that device (Fig. 1) is a sliding table on ball slideways, to which a disk mounting of single-grain diamond dresser and a micrometer screw were mounted. Thanks to the latter, given values of the conic chamfer may be applied with high precision (±3%) [13, 14].

Fig. 2. The width b and the angle χ of the grinding wheel conic chamfer shaped in experimental investigations Internal cylindrical surfaces of bearing rings mad from steel 100Cr6 with internal diameter d = 40 mm w were grinded. Table 1 presents the most important parameters of the realized experimental tests. During the tests, the initial and maximum grinding power P was registered, while after their termination, general axial machined surface roughness profile was registered on basis of which the following parameters were determined: Ra – arithmetic mean deviation of the assessed - profile; Rz – maximum height of the profile within - a sampling length; RSm – mean width of profile elements, within - a sampling length; Rdq – root-mean-square (RMS) slope of the - profile within a sampling length; RTp – material ratio of the complete profile. -

Fig. 1. Device for shaping macrogeometry of the grinding wheel active surface The device was equipped with a table drive system that consisted of a feeder, drive engine and a toothed bar. The reciprocal and traverse movement was steered using a contactor and limit switches placed in