Influence of processing time of a superhard ceramics sample on surface quality and edge rounding radius

Abstract

The article shows studies of the influence of vibration treatment time of an abrasive mixture consisting of 15% Type UDD diamond grains and monocorundum, on the surface quality of a sample made of superhard ceramics and the resulting radius of edge rounding. The studied samples were obtained from cubic boron nitride; it being extremely hard in hot state, which makes it possible to use it at very high cutting speeds. It is also characterized by good strength and heat resistance The investigation of the quality of the treated surface, estimated by the magnitude of the residual burr and the height of the microroughness of the surface of the part is very important in the study of vibrating processing of superhard ceramics. In vibration treatment, an increase in the processing capacity does not lead to a deterioration in the surface roughness due to the lapping process, which was achieved by selecting the vibration amplitude. In the process of chip removal during the diamond grinding of ceramics, individual diamond grains are involved, as well as the bundle of the circle. When studying the nature of the destruction of the ceramic surface by diamond grains, it was found that the grain leaves a clear trace without obvious chipping along the edges of the track at the beginning and at the end of the scratch. Diamond grain, having a sufficient hardness, begins to cut the shavings immediately after contact with the material. But the middle part of the scratch along the entire length has significant breaks along the edges. The arising of chips when a certain depth of grain penetration is reached is explained by the fact that with the increase in cutting depth, some new edges of the diamond grain come into operation, which results in the microcutting forces increase in the zone of the contact with the sample material, formation of highly dispersed chips and large breaks. The forces arising during grinding result in good endurance of diamond wheels, high quality of processing, and make it possible to choose rational technical parameters. The necessity of edge rounding can be justified by the complex of tasks facing the technologists. This is the cleanliness of the surface during machining and the cutting edge wear reduction. The cutting edges rounding radius and the speed of its formation are functions of the processing time, size and type of abrasive grain. These parameters are chosen empirically in a specific instance