MODEL AND CALCULATION OF ADHESION ENERGY OF TOOL AND PROCESSED MATERIAL CONTACT INTERACTION
The process of electric powered grinding by diamond wheels on a metal bond has been improved and the self-sharpening mode has been justified on the basis of the calculations of adhesion energy in the contact zone of tool and processed materials. Comprehensive studies of electric powered diamond grinding are performed on the example of hard alloy tool sharpening with consideration of the critical analysis of the literature data, manufacturing experience and the authors’ own researches using modern equipment and raster microscopy. Since clogging and wheel cutting property loss require periodic dressing, it is necessary to create the operation conditions of diamond wheels on a metal bond in the self-sharpening mode, when the specific consumption of diamond wheels is minimal. On the basis of the proposed model and mathematical formula for adhesion energy calculation, theoretical and experimental data are obtained for adhesion energy estimation depending on the dressing current density and effective grinding power. The values of the adhesion energy are found for the elements of the metal bonds and the elements of mineral ceramic hard alloys. The calculations have shown that the combined method of electric powered diamond grinding with simultaneous continuous electrochemical dressing of the wheel allows to reduce the adhesion energy level to the one when the surface energy of the adhesion interaction of the processed material and the elements of the diamond wheel is lower than the adhesion energy in the contact zone. In these conditions, clogging does not occur. These conditions include the dressing current density of the diamond wheel in the range from 0.25 to 0.45 A/cm2. It is determined that in accordance with the proposed model and on the basis of a mathematical formula for adhesion energy calculation, the combined method of electric powered diamond grinding with simultaneous continuous electrochemical dressing of the wheel allows to reduce the level of adhesion energy to the level when the surface energy of the adhesion interaction of the processed material and diamond wheel elements will be lower than the adhesion energy in the contact zone. Clogging does not occur in these conditions. It has been determined experimentally that the most rational value of the dressing current density, at which the self-sharpening mode is achieved, can be considered the value of iпр from 0.25 to 0.4 A/cm2. It has been found out that the combined electrochemical grinding with simultaneous electrochemical dressing of the wheel decreases the effective power by 4 times in comparison with grinding without the use of electric current.