Research On Grinding Subsurface Crackand Depth Prediction Of Optical Glass

Optical glass is a kind of hard brittle material, surface /subsurface damages in the process of grinding cause serious influence to the mechanical strength and optical properties of optical glass. The grinding mechanism of hard brittle materials and the research of surface crack are based on the quasi-static loading condition and the indentation fracture mechanics, without taking the effect of impact abrasive of grinding wheel into account. In this paper, the typical K9 optical glass material w as investigated. Starting from quasi- static properties of optical glass material, and combing material dynamic properties and scratching damage characteristics in the process of impact, the influence law of the impact effect on grinding process was analyzed and surface crack prediction model was put forward.Firstly, Vickers indentation experiments were performed on the K9 optical glass specimen. According to the material properties, loading force and indentation feature sizes, the material hardness and fracture toughness values were calculated with semi-empirical formulas. Using split Hopkinson pressure bar experiment device to carry out impact test of K 9 optical glass specimen, the material dynamic mechanical properties under different strain rate and material breakage forms were obtained. The impact of strain rate effect on the properties of material was analyzed.Secondly, single particle diamond of quasi-static and dynamic impact scratch experiments were conducted on K9 optical glass specimen. Comparing the differences between the d ynamic impact and quasi-static experiments through the surface and the surface morphology detection. The influence laws of different scratching parameters on force and surface/subsurface damage were analyzed, and the dynamic impact effect evaluation standard was established.Finally, the grind ing experiments were performed on the K 9 optical glass specimen. The influence laws of impact effects on the grinding force, surface/subsurface damage under different grinding parameters were studied through testing specimen surface/subsurface crack morphology. The K9 glass subsurface crack depth prediction model relating with gr inding parameters and surface roughness was proposed. According to the depth of subsurface damage of grinding experiments, the validity of the theoretical model was verified.