Calculation of radial material removal and the thickness of the layer with the current roughness when grinding brittle non-metallic materials

OBRABOTKAMETALLOV Vol. 23 No. 3 2021 technology Results and discussion For the purpose of experimental verification of the obtained dependencies, experiments were conducted on grinding samples during internal grinding of the hole. Samples (hole diameter – 150 mm, length – 250 mm) were ground on a machine RSM M 500 CNC by the tool AW 60×25×13 63C F90 M 7 B A 35 m/s (the grinding head speed – 35 m/s, the workpiece speed – 0.262 m/s). In order for each point of the surface to meet the wheel once in one pass, the longitudinal feed per revolution of the workpiece was chosen equal to the width of the grinding head bs (Fig. 8). According to the obtained experimental results, the maximum depth of micro-cutting and the thickness of the layer with the current surface roughness were calculated. The thickness of the specified layer was compared with the experimental data obtained using a profilogram of the polished surface. The obtained dependences of the removal of the material and the thickness of the layer with the current surface roughness on the transverse feed are similar to those available in the literature. If we approximate it with equations of the form = D n í y H S , then the exponent for y S will be equal to 0.44, which is in good agreement with the experimental data of other authors [17]. A comparison of the calculated and experimental data indicates its compliance with almost all feed values. The slope of the calculated curve is slightly different (the largest deviation is 21.34 % of the calculated values from the experimental ones) with a transverse feed of 0.5 µm/stroke. With an increase in the transverse feed, the differences in the calculated and experimental values of the surface roughness decrease. Minor differences between experimental and theoretical values in the feed range of 1 ... 2 µm/stroke can be explained by the fact that the number of vertices on the surface of the wheel is assumed to be constant during calculations, while according to research data [17–20] it increases with a decrease in the intensity of metal removal and transverse feed. But even if the number of abrasive grains remains constant, equations (8) and (10) model the real process of grinding holes made of brittle non-metallic materials quite well. Conclusions The developed mathematical models allow us to calculate the radial removal of the material and the thickness of the layer in which the current roughness is distributed when grinding brittle non-metallic materials. The proposed dependencies show the regularity of the removal of particles of brittle non-metallic Ta b l e 2 Influence of cross feed on micro-cutting depth, radial material removal and surface roughness № Cross feed rate S y , µm/stroke Actual depth t f , µm Radial material removal, µm Layer thickness with current roughness H , μm D r p D r x experimental accounting deviation, % 1 0.5 10.47 4.68 2.324 6.382 8.114 21.34 2 1.0 17.83 9.27 6.389 12.451 14.95 16.71 3 2.0 22.34 12.18 9.363 16.872 19.52 13.57 4 4.0 26.38 14.83 12.2 26.01 23.75 8.69 5 8.0 32.16 18.65 16.38 27.904 29.89 6.64 Fig. 8. Diagram of the internal grinding process