Precision Conditioning Of Diomand Wheels With Respect To Microstructured Surface Grinding

Introducing the super hard materials like silicon carbide ceramics and siliconnitride ceramics as mold material into micro-structured optic glass molding techniqueshas greatly improved the productivity. But the properties of high hardness, high stiffnessand consequently brittleness of the materials themselves make the ultra-precisiongrinding for the mold fabrication the key technology. With improvement of the research,the precision conditioning of diamond grinding wheel has been the technical bottleneckfor the ultra-precision grinding of micro-structure on the surface of super hard materials.Aiming at solving this problem, by means of research on precision condition ofprofile metal bonded diamond grinding wheel, this topic devote to the research onin-position conditioning of metal bonded diamond wheel. Firstly, according to theanalysis and summary on the current domestic and international study on precisioncondition of profile metal bonded diamond wheel, EDM conditioning first and thenprecision mechanic condition have been proved useful and effective, not only improvingprecision, but also the surface topography of grinding wheel. On the basis of thelaboratory condition, absorbing the past experiences, this thesis aimed at conditioningthe existing R-shape diamond wheel and V-shape diamond wheel through usinggenerating method; at designing the NC track and write the related CNC program.Secondly, based on the analysis of the theory and the application of dry-EDMconditioning, dry-EDM conditioning experiments respectively on the R-shape diamondwheel and V-shape diamond wheel have been carried out. The results showed that highrotation accuracy and high shape accuracy of arc grinding edge can be achieved afterR-shape diamond wheel being conditioned by dry-EDM; although dry-EDMconditioning V-shape diamond wheel could gain high rotation accuracy, the tip-radius ofV grinding edge was still too big for tip discharge effect.Thirdly, the V-shape diamond wheel grinding-dressing experiments were carriedout using GC dressing wheel. The results showed that the rotation accuracy can beachieved to0.6μm, and the V-tip radius can be reduced to17μm. The observation ofsurface topography also showed that the diamond abrasive bared perfectly withreconsolidation layer removed. Moreover the rapid abrasion of GC dressing wheel leadsto the differences of dressing precision’s distribution law on the surface of V-grindingedge using different NC trace. Hence the GC dressing wheel is not suitable for R-shapediamond wheel conditioning. So the diamond wheel was chosen to be the substitutionfor R-shape diamond wheel conditioning. But the experiments’ results showed that thediamond abrasive still wore rapidly and the diamond dressing wheel was liable to beloaded. And dressing wheel loading also would deteriorate dressing effects.In the end, the conditioned wheels was applied to gain the V-groove arrays on the surface of silicon nitride ceramic and Arc-groove arrays on the surface of silicon carbideceramics. The results showed that the roughness of V-groove arrays has been achievedto134.6nm about, the radius of V-tip is bigger than45μm; the roughness of Arc-groovearrays was146.1nm about, and profile accuracy was53.0557μm for the crack with thedepth of7.2530μm of the diamond wheel. The observation of surface topography ofsilicon nitride ceramic showed that the bulk crack was easily induced from poresexisting in the ceramics; surface topography of silicon carbide seemed better than theformer, with little surface defects.