Study On Brazing Monolayer Diamond Tools With The Orderly Arraying Of Diamond Grits

As a novel diamond tool for machining of brittle and hard materials, mono-layer brazed diamond tool owns high diamond protrusion and bonding strength. Orderly arraying of diamond grits on the tool has drawn much attention and is considered as a main trend for improving the performance and the life of the diamond tools.In this thesis, four kinds of automatic diamond grit arraying schemes: electromagnetic arraying, electrostatic arraying, automatic mechanical mesh screen arraying, automatic suction mesh screen arraying are designed with their concept structures. Then four orderly arraying patterns: grid, concentric circle, spiral and non-uniform even were used to fabricated the mono-layer brazed diamond grinding tools to compare with the randomly arrayed tool. The effect of the orderly arraying on the wear of the tools, surface roughness of workpieces, character of grinding forces in the grinding process are investigated later. At last, the microstructure of the interface between the diamond and the Ni-Cr alloy for different brazing temperature and holding time is observed.The result shows that by 20 hours of grinding, the randomly arrayed diamond tool has lost the machining ability, but four orderly arrayed diamond tools still show good grinding performance. The weight wear and height wear of the orderly arrayed diamond tools are less than that of randomly arrayed. The diamond in the spiral pattern arrayed is mainly worn in the form of micro-cracking, but the diamond in the randomly arrayed is mainly worn in the form of macro-cracking with the fast flattening of the cutting edges.In the cut-in and the stable grinding stages, both of the absolute values and the amplitude of grinding forces of four orderly arrayed tools are smaller than that of randomly arrayed. When the grinding depth is increased, the grinding force of the concentric circle and the spiral pattern arrayed tools are the least all the time, but the grinding force of the randomly arrayed tool increase significantly, the grinding force of grid pattern arrayed tool remains stable.A transition region between the diamond and the Ni-Cr alloy is found with the rich of Cr element. It is also found that there is a graphitization layer on the boundary of diamond grit. The thickness of the graphitization layer is increased with the increase of the brazing temperature.