W.J. Zong

Crucial fabrication with rounded diamond cutting tools

In order to satisfy the machining of high precision components, much higher accuracies have been put forward for diamond cutting tools. From the viewpoints of fabrication and utilization of rounded diamond cutting tools, the material removal mechanism of lapped diamond surface layer is studied by lapping experiments. And also, the crucial processes for tool fabrication and re-lapping are analyzed and discussed. Moreover, the working state of lapping equipment affecting tool lapping quality is lucubrated. At the same time, the representative qualifications of rounded diamond cutting tools are defined and their assessment methods are proposed, respectively. Finally, in terms of the relationship of the removal mechanism and tool lapping quality, the lapping parameters are optimized for the fabrication of high precision diamond cutting tools. The results indicate the sharpness can be reduced to 30nm.

A study on the diamond lapping direction determination

The anisotropy of material removal rate for diamond gives a method to control the lapping rate of diamond specimen, i.e. changing the lapping direction. This requires comprehension on the relationship of the material removal rate and the lapping direction for diamond. This paper provides a method to figure out the diamond lapping direction. By preprocessing a straight edge formed by lapping a surface intersects with the required machining surface, the diamond lapping direction can be figured out under the Confocal Scanning Laser Microscope only if the crystal directions of the two surfaces are determined at first. The advantage of our method is that there is no need to consider the position and posture of the diamond specimen fixed on the holder.

A novel method for high efficiently lapping of rounded diamond cutting tools

Rounded diamond cutting tools are widely used in ultra-precision cutting. The lapping quality of nose arc plays a very important role on the accuracy of the machined surface. However, the diamond has strong anisotropy, which is embodied in the nose arc of rounded diamond cutting tools. Therefore, simple cylindrical lapping is not an efficient method to lap the nose arc of the rounded tools. It is urgent to find a best way to lap the nose arc with high precision and efficiency. Firstly, based on periodic bond chain (PBC), a ratio model of material removal rate is built for nose arc of diamond cutting tools. And then, the optimal lapping direction is obtained. Second, two novel lapping methods are proposed according to the formula of material removal amount: one is variation of lapping pressure for uniform material volume removing and the other is variation of lapping time. Lastly, the design criterion for rounded diamond cutting tools is presented. It is recommended to use the tool with crystal plane {110} as rake face and flank face.