More efficient deep grinding

Abstract

Currently, abrasive machining is used to improve product quality and productivity and also for preliminary and final machining in a single pass. Deep grinding is of particular interest here. In this method, with considerable metal removal in a single pass, problems arise in preventing thermal and other damage to the part. The kinematic aspects of deep grinding were analyzed in detail over the phases of the complete cycle in [1, 2]: in tool insertion; steady grinding; and removal of the grinding wheel. The productivity of the process is evaluated in terms of the volume of the layer removed in a single turn of the wheel. In specified conditions, this allows the change in cutting rate to be taken into account; in other words, it permits quantitative analysis. The processes in the contact zone of a single abrasive grain with the metal, within the range of wheel rotation bounded by the points of the grain entry into the metal and its exit, were subjected to qualitative estimation in [3]. It was found that, within this range, the temperature and pressure vary significantly in the metal. This is associated with change in the rate of removal of microvolumes of metal as the wheel turns. It is of interest to investigate deep grinding by analysis of the rate of metal removal in the sector of the wheel whose central angle is determined by the wheel radius and the cutting depth. This approach permits study of the physics of metal dispersion at different cutting speeds and depths in the actual contact zones of a single grain (a single point of the wheel) between its entry in the blank and its subsequent exit, in both ordinary and deep grinding. For the sake of simplicity, all the calculations relate to steady grinding. The arc radius remains constant as the center of the wheel moves; the displacement l ce of the center O 0 is equal to the longitudinal supply; l ce / ϕ = const, where ϕ is the contact angle (Fig. 1). The angle ϕ = arccos[( r ‐ t )/ r ], where r is the mean radius of the wheel’s working surface; t is the grinding depth. The thickness of the cut layer at any point b = l ce sin ϕ . The volume of metal removed during the contact time is enclosed between two cylindrical surfaces (impressions of the wheel) and parallel planes: the