DEVICE FOR DETERMINATION OF THE SURFACE HARDNESS OF ABRASIVE TOOLS

Abstract

Analysis of various procedures currently used for determination of the hardness of the abrasive tools in the Russian Federation and abroad showed that the processes of measuring the surface hardness of tools differ from the processes occurred upon interaction of the working surface of the tool with the workpiece surface of the item. All known methods of hardness determination are thus formalized, conditional and and irresponsive to the essence of physical and mechanical processes of grinding. Another disadvantage is their low sensitivity to the change in the structural and mechanical properties of the tool under the impact of environmental factors, coolant-cutting fluid, etc. A pendulum dispersometer is developed to study the surface hardness of tools and simulate the real contact between their working surface and the workpiece surface upon grinding. The design of the pendulum dispersometer, mechanics, and detailed technique for determination of the relative hardness using the dispersion time constant are presented. A close correlation is observed between the hardness values determined with the pendulum dispersometer and specific volumetric fracture energy when the surface of the abrasive tool is dispersed. Data on the hardness values obtained using a pendulum dispersometer and sand-blasting method are compared. Electrocorundum tools on a ceramic bond of different grain sizes (16, 25, 40) with a constant hardness of SM2 determined by the sand-blasting method according to GOST 18118-97 are used as samples. An analysis of the results proved that the hardness values obtained on a pendulum dispersometer reliably reflect the real operating conditions of abrasive tools.