大尺寸高端轴承滚子表面缺陷检测显微散射成像机理研究

Research on Large Size Advanced Bearing Rollers Surface Defects Inspection Microscopic Scattering Imaging Mechanism

高端轴承广泛应用于高温、高速、高压等极端环境,高端轴承滚子作为高端轴承的关键零部件,其表面质量直接决定了所在高端装备的性能与可靠性,对其表面开展早期的缺陷检测至关重要。高端轴承滚子工作表面具有柱面、锥面、鼓形面等旋转曲面形状。此外,滚子材料为金属,其复折射率属性加上一定程度的表面粗糙度特性,导致其表面缺陷的光学散射特性极为复杂,常规光场采集的缺陷图像难以获得较好的缺陷对比度。针对上述高端轴承滚子工作表面缺陷检测难题,通过有限元法建立了表面微观缺陷的远场电磁散射仿真模型,并通过菲涅尔衍射积分公式,根据有限元近场分布求解结果计算远场分布,仿真分析了滚子表面不同照明角度、尺寸、类型等参数条件下的缺陷散射成像规律。结果表明提出的求解方法与全空间域有限元求解方法获得的缺陷远场散射光强分布基本一致,且在照明光源入射角0°~15°范围内,可采取同轴场照明,在30°~37°范围内,可采取暗场照明。可为实际缺陷的多光场散射成像照明与成像系统的设计提供理论依据,助力提升我国高端轴承的国产化能力。

Advanced bearings are widely used in extreme conditions such as high temperature,high speed and high pressure environments.As a key component of bearings,the surface quality of advanced bearing rollers directly determines the performance and reliability of advanced equipment.Hence it is very important to carry out early defect inspection on bearing rollers surface.The working surface of the bearing roller contains cylinder,cone,drum,etc.In addition,roller material is metal and its complex refractive index property combined with a certain degree of surface roughness characteristics will lead to extremely complex optical scattering.So,it is difficult to obtain good contrast in images collected by conventional light field.In order to solve these problems,a far-field electromagnetic scattering simulation model of surface microscopic defects by finite element method is built in this paper.The far-field distribution based on the solution results of the near-field distribution of finite element is calculated by Fresnel diffraction integral formula.The defect scattering imaging under different illumination angles,defect sizes,defect types and other parameters is simulated.Results show that the intensity distribution of the far-field scattered light obtained by the proposed method is basically consistent with that obtained by the full-space finite element method.In the illumination incident angle range 0°-15°,coaxial field illumination can be taken for defect inspection.In the illumination incident angle range 30~37°,dark field illumination can be taken for defect inspection.The results can provide a theoretical basis for multi-field scattering imaging system design and also help to improve the localization ability of China advanced bearings.