Studies On Grinding Mechanism Of PCD Cutting Tool And Machining Titanium Alloy With It

Due to its excellent hardness and abrasive resistance which can improve the machining efficiency and tool life, the polycrystalline diamond (PCD) tool has be applied in practice for about30years. But currently, the sharpening cost of PCD tool is high, the grinding quality is not stable, and when machining some difficult-cut materials, as well as titanium alloys, the using results are not satisfactory enough. These problems prevent the PCD tool from being more widely used. To improve the manufacturing ability and applying technique of PCD tool, and then widen its usage, this paper used diamond grinding wheels with different binding agents to sharpen tool, analyzed the mechanism of sharpening, and then studied the law of machining titanium alloy with it.Firstly, the PCD tools were ground with vitrified bond, metal bond and resin bond’s diamond grinding wheel respectively. According to the experiment results, the curves were drawn between the removal rate and wear ratio, the topography images of the surface and edge were observed with a scanning electron microscopy(SEM), and then the variation of removal rate and wear ratio and the grinding mechanism of PCD tool with different bond agents according to grinding quality were analyzed. Secondly, the orthogonal test table was formulated for the titanium alloy’s cutting test by choosing appropriate cutting speed, cutting depth and feed rate, the cutting force was measured with a dynamometer. According to the results, the cutting force curves were drawn and the relationship between cutting force and cutting parameters and the cause of the relationship were analyzed. Finally, the author changed one of the three parameters, kept the other two constant and completed three sets of titanium alloy’s cutting experiments. In these jobs, the roughness Ra and Rz were measured, the comparison graph was drawn and then the relationship between cutting parameters and roughness and the cause were analyzedThe experiment results show that the removal rate of resin bond’s diamond grinding wheel is always higher than that of the other two kinds, when the axial feed reaches a critical value the removal rate of metal bond’s diamond grinding wheel begin to be higher than that of the other two kinds, and when grinding with metal bond’s diamond grinding wheel the abrasive grain would break to keep sharpness which achieves the grinding process. The surface of resin bond’s diamond grinding wheel deforms due to the heat generated by grinding, so the low cutting speed should be used. The vitrified bond’s grinding wheel is made by several materials, so both the bond and the abrasive grain would fall off and leaves pits on the surface of PCD tool. When cutting titanium alloy, static cutting force changes a little along with cutting speed but changes a lot along with feed rate and cutting depth. The dynamic force Fdynaz changes apparently with cutting parameters, but Fdynax and Fdynay changes little. The roughness of workpiece surface changes a little with cutting speed but changes a lot with feed rate and cutting depth.