Study on Finishing of Curved High Performance Ceramic Surface by using a Semispherical Diamond Grinding Tool

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The purpose of this research project is to first develop a dual-axis spherical diamond grinding tool for finishing the curved high performace ceramic surfaces, secondly study the finishing mechanism and properties of the dual-axis grinding tool in which the semi-spherical (or a part of spherical body) diamond grinding wheel can be revolve on both the main spindle and the wheel axis at the same time.The grinding experiments for example Si_3N_4 and Al_2O_3 ceramics are carried out by using the developed grinding tool directly attached to the main spindle of the N/C milling machine tool. On the other hand, in order to examine the breaking strength of the ground Al_2O_3 ceramics, the three-points flexural strength tests are done.The results obtained are summarized as follows.(1)By dual-axis grinding the vertical surfaces of Si_3N_4 ceramics with the semispherical diamond wheel, we can obtain the surface roughness of less than 5<micrn>mRz and the stock removal corresponding to the given depth of cut.(2)By the dual-axis diamond grinding wheel with the part of spherical body, the surface roughness of about 1.3<micrn>mRz and 2.4<micrn>mRz can be obtained for the plane surfaces and the vertical surfaces of Al_2O_3 ceramics respectively. The normal forces are relatively small values of about 7N for the plane surfaces and 4N for the vertical surfaces.(3)By the tree-points flexural strength tests of Al_2O_3 ceramics, the average values of flexural strength are 50 kgf/mm^2 for the plane surfaces and 41 kgf/mm^2 for the vertical surfaces. It is noticed that the strength for the vertical surfaces is rather higher than that of general Al_2O_3 ceramics (about 40 kgf/mm^2).