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 Ta b l e 1 Comparison of numerical results with those based on simplified dependencies № Actual depth t f , µm Numbe r of con- tact s , n Radial material removal, µm Layer thickness with current roughness H , μm Contact area length, mm D r p D x r dependency (6) simplified model (10) deviation, % 1 9.22 5 4.096 1.857 6.998 6.982 0.23 0.0008 2 14.65 2 7.458 4.603 11.849 11.795 0.46 0.0011 3 16.04 3 8.345 5.428 13.161 13.12 0.31 0.0011 4 23.76 7 13.37 10.55 21.19 20.94 1.17 0.0014 5 27.92 6 16.11 13.53 25.49 25.33 0.63 0.0016 6 29.77 12 17.34 14.89 27.64 27.31 1.19 0.0017 7 30.58 9 17.88 15.47 28.369 28.17 0.71 0.0017 Fig. 7. Effect of wheel speed on material removal (– – –), caused by brittle fracture and on layer thickness with current surface roughness ( ––– ): 1 – t f = 9.22 μm, 2 – t f = 14.65 μm; 3 – t f = 23.76 μm, 4 – t f = 30.58 μm In the studied range, the thickness of the layer with the current surface roughness changes almost proportionally to t f . So, for wheels with a grain size of F90, with an increase of t f by almost 2 times (from 9.22 μm to 14.65 μm at V k = 35 m/s) the thickness of the layer with the current roughness increases by 1.92 times (from 5.2 μm to 10.01 μm). The radial removal of the material increases more significantly with an increase in the depth of micro-cutting than the thickness of the layer with the current surface roughness. Thus, with an increase of t f by 1.59 times (from 9.22 μm to 14.65 μm) (Fig. 5), the radial removal increases by 3.1 times (from 2.38 μm to 7.34 μm). This effect of the depth of micro-cutting on the radial removal is explained by the fact that with increasing t f not only the thickness increases, but also the length of individual sections, the brittle component of the removal increases. With an increase in the speed of the wheel, the radial removal increases, the thickness of the layer with the current surface roughness decreases. With an increase in the speed of the workpiece at t f = const, the radial removal of the material decreases, the thickness of the layer with the current surface roughness increases.