Prediction of Residual Stress Layer Depth in Grinding Fused Quartz

Fused quartz has excellent physical and chemical properties, and is widely used in manufacture of optical components and other industries and many fields of modern science and technology. However, fused quartz glass is a high hard and brittle material. Cracks, residual stress and other damage are likely to occur during processing. The surface residual stress layer of the workpiece after grinding is under the crack layer, its position is hidden and difficult to observe. During the use of the workpiece, it is easy to expand into cracks under the action of external load, which affects the design of subsequent process parameters and the service life of the workpiece. Therefore, researching on the depth of surface residual stress layer after grinding is helpful to determine the residual processing allowance and improve the working performance of the workpiece. In this paper, the discrete element model of single particle grinding fused quartz was established by the discrete element method. By changing the cutting depth corresponding to different particle sizes in the simulation process, the influence of diamond particle size on the subsurface damage depth of the workpiece was studied. In the experiment, the fused quartz workpiece was ground with resin-based corundum grinding wheel. The grinding process only changed the particle size of the grinding wheel, and the other process parameters were fixed. Angle polishing method and differential corrosion method were used to measure the depth of the subsurface crack layer and the damaged layer, and the depth of the residual stress layer was calculated and the discrete element simulation results were verified. The results showed that when the particle size was 7, 14, 28, 40 μm, the simulated crack layer depth was 2.53, 3.02, 4.07, 7.39 μm, and the residual stress layer depth was 0.75, 1.00, 1.34, 2.33 μm, respectively. The depth of crack layer was 2.51, 3.14, 4.65, 8.16 μm, and the depth of residual stress layer was 0.86, 0.93, 1.31, 1.87 μm. It could be seen that with the increase of particle size, the removal of brittleness on the workpiece surface became more obvious, the surface quality deteriorated, and the depth of subsurface crack layer and residual stress layer increased. The residual stress layer was distributed below the crack layer, and there would be stress concentration at the crack tip. When the particle size was large, the stress at the tip would also increase as the subsurface crack of the workpiece expanded to the inside of the material after grinding. The depth of the residual stress layer also increased. The deviation between the crack depth and the experimental value was less than 15%, and the residual stress depth was less than 25%. The depth of the residual stress layer was about 1/4~1/3 of the depth of the crack layer. The proportion decreased gradually with the increase of the particle size. Therefore, the depth of residual stress layer can be predicted by obtaining the crack layer depth. The discrete element method can be used to simulate the grinding process of a single abrasive particle, so as to obtain the crack layer depth, and then predict the residual stress layer depth after grinding of fused quartz. The reference is provided for the grinding process parameters. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.