Influence of local temperatures on the adhesion of the blank to abrasive grains

Abstract

Kinetic data on the adhesion of the blank to an abrasive grain of the grinding wheel indicate that the bond between the abrasive and the metal is mainly due to capture [1]. According to current concepts regarding the bonding of materials in analogous conditions, the most important factors are the pressure, the temperature in the contact zone, and the time of exposure [2]. It is found that, in any grinding conditions, the contact surfaces of the abrasive grain with the chip and the blank include sections where the pressure exceeds the yield point of the material in the blank [3]. Experiments on metal adhesion to individual abrasive grains in microcutting (scratching) show that this process is intensified with increase in sample temperature [4]. To establish the relation between the adhesion rate and the local temperature in zones adjacent to the adhesive grain, the thermal interaction of the objects in contact during microcutting may be analyzed theoretically and investigated experimentally. In developing physical and mathematical models of the thermal process, the actual shape of the contacting objects—the blank, the abrasive grain, the chip, and the grain holder—is taken into account, as well as the location of individual sources of heat generation and their density distribution and also the temperature dependence of the thermophysical properties of the objects and the mechanical properties of the sample. In addition, the relative displacement of the contacting objects (the holder with the grain relative to the sample; and the chip relative to the grain) is taken into account. The components of the microcutting force required to calculate the power of the heat-generation sources are determined from analytical formulas [3]. It is assumed that the abrasive grain is a cone (vertex angle 2 γ ; wear length l 2 ). In other words, the grain is of the same shape as in experiments on microcutting (Fig. 1) [4]. Some of the heat from the abrasive grain passes to the holder.