Simulation And Experimental Studies On Precision Grinding Of Optical Glasses Using Coarse-grained Diamond Wheel

As optical glasses are widely used in the field of aerospace, photoelectrictechnology, space technology and precision engineering, etc. Requirements for theirmachining efficiency and quality become higher and higher. Fine-grained grindingwheel can achieve precision grinding of optical glasses, with shortcomings of lowmachining efficiency and frequent truing. Coarse-grained grinding wheel hasadvantages of high machining efficiency and wear resistance during grinding. If coarse-grained grinding wheel can achieve precision grinding, it will improve the machiningefficiency greatly. In this paper, surface grinding experiments for optical glasses arecarried out with coarse-grained diamond wheel and fine-grained diamond wheel.Grinding mechanical residual stress, grinding ratio and surface quality will beinvestigated to analyze the advantages and disadvantages with grinding wheel ofdifferent sizes. At last, precision grinding of optical glasses with coarse-grainedgrinding wheel can be achieved.Firstly, Abaqus is used to simulate mechanical residual stress, which is caused bygrinding BK7, fused quartz, fused silica with coarse-grained and fine-grained grindingwheel. Nano-indentation experiments are carried out to get the materials’ constitutivemodels. Establishing normal grinding force equation according to the measurement ofnormal grinding force during surface grinding experiments. Simulation analysis resultsshow that coarse-grained grinding wheel can cause less stress damage than fine-grainedgrinding wheel under the same processing parameters. So coarse-grained grindingwheel is more suitable for grinding optical glasses from the aspect of residual stress.Secondly, orthogonal optimization experiments of grinding BK7with coarse-grained electroplated diamond wheel and fine-grained resin bond diamond wheel arecarried on to get their optimum processing parameters. Results show that optimumprocessing parameters of coarse-grained wheel are: grinding depth is1μm, feed speed is100mm/min, wheel speed is2000rpm. optimum processing parameters of fine-grainedwheel are: grinding depth is0.5μm, feed speed is100mm/min, wheel speed is1200rpm.These parameters can be used as the processing parameters of subsequent grindingexperiments.Lastly, surface grinding experiments of BK7with coarse-grained electroplateddiamond wheel, fine-grained resin bond diamond wheel and fine-grained cast iron bonddiamond wheel are carried out to study the grinding efficiency and quality of coarse-grained and fine-grained grinding wheel. Grinding ratio can be calculated by getting thewheel wear. Otherwise, grinding optical glasses under the optimal parameters with theabove grinding wheels and analyzing the surface quality and sub-surface damage.Experimental results reveal that fine-grained grinding wheel can achieve higher surface finish, but its grinding ratio is less than10. Coarse-grained grinding wheel can machineoptical glasses whose surface roughness is less than20nm and depth of sub-surfacedamage is less than3μm. While its grinding ratio can get230during precision grinding.Coarse-grained grinding wheel can achieve precision grinding of optical glasses withhigh efficiency after truing, which is of great significance for improving the efficiencyof grinding optical glasses.