TY - GEN
T1 - Crack depth uniformity control techniques for large scale fused silica optics in grinding process
AU - Zhou, Lian
AU - Zheng, Nan
AU - Chen, Xianhua
AU - Liu, Mincai
AU - Zhang, Qinghua
AU - Wang, Jian
AU - Li, Jie
N1 - Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
PY - 2019
Y1 - 2019
N2 - In order to improve the overall efficiency of machining and the defect quality of large aperture fused silica optics, it's necessary to strictly control the crack defects and their depth uniformity in the first grinding process. Firstly, the morphology of three typical defects affecting the uniformity of crack depth was analyzed, which were scattered superficial sand holes, continuous linear defects and dotted linear defects. Then according to the morphology, the causes were investigated and the control techniques were proposed. The scattered superficial sand holes were caused by the large size glass powder, the diamond particles dropped from the grinding wheel and other foreign body impurities in the grinding fluid, which had been squeezed into the surface of the element by the grinding wheel. Through the clean filtration of grinding fluid, the quantity of such defects could be effectively reduced. The continuous linear defects were caused by stress concentration at the two sharp edges of the grinding wheel. Arcing the two sides of wheel could reduce the machining stress at the edges and avoid the occurrence of continuous linear defects. The dotted linear defects were caused by the stress concentration of the grooves on the surface of the wheel during grinding. After optimizing the dressing parameters to reduce the dressing force and avoid the grains of dressing wheel being embedded into the grinding wheel surface, all the grooves on the wheel surface and all the dashed line defects on the element surface disappeared practically. At the last, after integrating all the above control techniques, the grinding experiment of large scale fused silica optics was carried out. The scattered superficial sand holes, continuous linear defects and dotted linear defects on the surface of element after grinding were obviously alleviated. The crack depth of the whole aperture was between 4μm and 7μm. All the results indicated that the control techniques were efficacious.
AB - In order to improve the overall efficiency of machining and the defect quality of large aperture fused silica optics, it's necessary to strictly control the crack defects and their depth uniformity in the first grinding process. Firstly, the morphology of three typical defects affecting the uniformity of crack depth was analyzed, which were scattered superficial sand holes, continuous linear defects and dotted linear defects. Then according to the morphology, the causes were investigated and the control techniques were proposed. The scattered superficial sand holes were caused by the large size glass powder, the diamond particles dropped from the grinding wheel and other foreign body impurities in the grinding fluid, which had been squeezed into the surface of the element by the grinding wheel. Through the clean filtration of grinding fluid, the quantity of such defects could be effectively reduced. The continuous linear defects were caused by stress concentration at the two sharp edges of the grinding wheel. Arcing the two sides of wheel could reduce the machining stress at the edges and avoid the occurrence of continuous linear defects. The dotted linear defects were caused by the stress concentration of the grooves on the surface of the wheel during grinding. After optimizing the dressing parameters to reduce the dressing force and avoid the grains of dressing wheel being embedded into the grinding wheel surface, all the grooves on the wheel surface and all the dashed line defects on the element surface disappeared practically. At the last, after integrating all the above control techniques, the grinding experiment of large scale fused silica optics was carried out. The scattered superficial sand holes, continuous linear defects and dotted linear defects on the surface of element after grinding were obviously alleviated. The crack depth of the whole aperture was between 4μm and 7μm. All the results indicated that the control techniques were efficacious.
KW - Axial Profile of Wheel
KW - Crack Depth Uniformity
KW - Fused Silica Optics
KW - Grinding Fluid
KW - Surface Quality of Wheel
KW - Ultra-precision Grinding
UR - http://www.scopus.com/inward/record.url?scp=85065973618&partnerID=8YFLogxK
U2 - 10.1117/12.2524151
DO - 10.1117/12.2524151
M3 - 会议稿件
AN - SCOPUS:85065973618
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Second Symposium on Novel Technology of X-Ray Imaging
A2 - Tian, Yangchao
A2 - Liu, Peng
A2 - Xiao, Tiqiao
PB - SPIE
T2 - 2nd Symposium on Novel Technology of X-Ray Imaging
Y2 - 26 November 2018 through 28 November 2018
ER -