Non-contact Measurement And 3D Graphical Evaluation Of Micron-scale Protrusion Topography Of Diamond Grinding Wheel

Grinding technique using a diamond grinding wheel is an effective method for the precision machining of the hard and brittle materials. Based on general grinding theory, the single abrasive grain cutting depth can be reduced with increasing the active grain number, and also diamond grain break-off that does damage to the machined surface can be prevented by reducing the abrasive grain size, ultimately leading to the ductile-mode mirror grinding of hard and brittle materials. Generally, diamond grinding wheel which are finer than #3000 are used, and machining efficiency is extremely limited. Therefore, the coarse diamond grinding wheel of #46,#270,#60 are chose to realize the ductile-mode efficient grinding of hard and brittle materials in this paper. So the key problems of how diamond grains are distributed on the wheel working surface and whether micro diamond grains can be parameterized, how grain protrusion parameters influence grinding performance need to be researched. The non-contact measuring technology and graphical processing approach are used to establish the parameterization mode of grinding wheel surface topography, and the relationship between parameters and performance of accurate grinding is analyzed in this paper.First an optical glass cutting test with a #46 single diamond grain was conducted, the shape error, the angle and the tip arc-radius of V-groove are modeled through the non-contact laser measurement. The results show that the ductile-mode cutting of the brittle glass may be conducted using a single diamond grain when the cutting depth is less than 0.386μm. If an integrate V-groove is machined, the cutting depth still need to be less than 0.365μm.Then, the 3D topographical data of truncated #270 diamond grinding wheel surface has been acquired by a laser detection method. Through the graphics processing of micro protrusion topography of wheel, the grain protrusion height, grain protrusion volume, grain rake angle and clearance angle were modeled. The results show that average values of grain protrusion height, grain protrusion volume and clearance angle of truncated grinding wheel are smaller than the ones of ideal grinding wheel, but the grain rake angle of truncated grinding wheel is larger. In comparison with ideal grinding wheel, the truncated grinding wheel may increase the active grain number by 36 times and the active grain volume by about 194 times for the depth of cut of 2μm, thus leading to a decrease in grain cutting depth and an increase in grain cutting edge rigidity. Therefore, the truncated diamond grinding wheel can improve ground surface roughness of quartz glass by about 80%, but increase the grinding force has by about 40 times, thus requiring greater grinding energy.Finally, the axial-feed mirror grinding on the silicon carbide ceramics was ground by using the truncated #60 diamond grinding wheel, the 3D data of wheel working surface are measured by using white light interference detection. The results show that grain protrusion height, grain protrusion volume, and clearance angle are larger compared with the factory wheel, but the grain rake angle is smaller, which is different from the truncation mechanizations of finer #270 diamond grinding wheel. In addition, the truncated #60 diamond grinding wheel can increase the active grain number by about twice and active grain volume by about twice for the depth of cut of 2μm, which accords with the feature of the truncated #270 diamond grinding wheel.As a result, active grain number and active grain volume can be regarded as main parameters to evaluate the grinding performance. Increasing these parameters may realize the ductile-mode mirror grinding of hard and brittle materials using a coarser diamond grinding wheel.