Precision Conditioning Of Coarse-grained Diamond Wheel Applied In Optical Glass Grinding

At present, optical glasses, especially large-size optical elements, are usuallyprecision/ultra-precision ground by fine-grained grinding wheel, with defects offrequent truing and low efficiency. However, coarse-grained diamond wheel can beused with high efficiency and low cost, while precision truing technology is the keypoint.Firstly，the paper explored the feasibility of using iron-based material ontruing the coarse-grained diamond wheel. Through simulation results, the Cr12materials was ensured for rough truing. With dry grinding method, grinding heatand grinding force can accelerate the wear of the diamond. As the diamond is morestable and very hard, whether or not it can have the mechanical and chemical effectwith iron-based materials is the key to truing. So the multiple abrasive scratchexperiment was designed to verify it. The results show that, diamond can beseriously worn and graphite and C60can be detected after scratching, whichdetermine the feasibility of Cr12material to true the diamond wheel.Secondly, electroplated diamond grinding wheel is efficient trued. The stepsare as follows：in the first, rough truing using Cr12the rotational error can bereduced to10μm or less through the wear removal mechanism. Then, using theELID technology, fine truing using a diamond cup-shaped truing wheel therotational error can be reduced to6μm through the cleavage remove mechanism.Comprehensive, this truing process is effective and efficient for electroplateddiamond wheel truing.Finally, for different stages of truing, grinding experiments for BK7, fusedsilica, fused quartz three optical glasses were taken out. Profilometer and SEMwere used to analysis different truing effect on the grinding surface quality, and thedynamometer analysis grinding force. Get the conclusion：When rotational error islarge, material mainly was removed by brittle fracture, along with rotational errorreducing, the roughness Ra and the surface accuracy PV of grinding surfacegradually increased, and change to the plastic removal. When rough truing, withthe rotational error smaller, the tangential and normal grinding force increasesgradually. When after fine truing, with its rotational error further reduce, thetangential grinding force and normal grinding force actually was decreasing. Afterprecision truing, coarse abrasive electroplated diamond wheel can be processedbetter workpiece surface quality.