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带钢表面缺陷视觉检测系统关键技术研究 总被引:4,自引:0,他引:4
为满足钢板表面缺陷在线检测系统宽幅面、高速、高分辨率的检测要求,讨论了基于线阵CCD的钢板表面缺陷视觉检测系统实现的关键技术;优化设计了视觉检测系统的光学照明部分,以检测不同类型的缺陷。通过软件系统的特殊设计,以保证实时在线检测。针对缺陷图像低对比度、高噪声的特点,提出了基于灰度统计特性的图像边缘检测方法,并实现了对缺陷图像的自适应阈值分割。依据图像的缺陷统计特性,定义了缺陷的灰度、几何等特征量,用于缺陷分类。本系统样机已在实验室环境下运行。 相似文献
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采用超声△衍射法和TOFD法对模拟缺陷进行检测,得出了缺陷检测波形图和B/C扫描图.对比分析了超声△衍射法与TOFD法的检测结果.实验表明利用超声△衍射法能够识别近表面垂直表面的面状缺陷,有效地对缺陷进行定位,能够很好地克服表面盲区,对缺陷的检测识别能力不受缺陷方向限制.从检测结果数据可以看出超声△衍射法的检测灵敏度和缺陷识别能力优于TOFD法. 相似文献
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脉冲涡流是一种可以对飞机多层铆接结构中缺陷进行有效检测的无损检测技术。本文通过研究低频涡流与脉冲涡流检测技术,设计和实现了圆柱形差分检测传感器,对铆钉周围出现的缺陷进行了检测。通过轴向扫描时获得的峰值曲线对缺陷的轴向宽度进行了定量检测。通过缺陷的瞬态感应电压信号,利用峰值、过零时间等特征量对缺陷造成的不连续性和损耗程度进行了检测分析。试验结果证明文中设计的圆柱形差分传感器可以对多层铆接结构中的缺陷进行有效检测,低频脉冲技术在飞机铆接结构缺陷的检测中具有很好的使用前景。 相似文献
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中国已成为笔类产品生产大国与出口大国,而笔管检测是制笔行业的关键工艺技术。针对目前制笔行业中笔管检测的需求,设计了笔管缺陷自动化检测系统,以提高笔管缺陷检测效率及笔管制造企业的生产质量。基于机器视觉及重心分类装置,采取分模块检测系统,对笔管的缺陷形态、类型进行鉴别与统计,高效率、高精度地实现笔管缺陷检测、残次品剔除与自动分拣。采用缺陷自动检测算法,利用计算机视觉检测技术进行缺陷边缘检测,分割出笔管的缺陷区域并定义主要缺陷类型,完成对笔管缺陷的判断与分类。通过构建、训练卷积神经网络,得到了拟合度较高的卷积神经网络模型,用于分析笔管的缺陷情况。实验结果表明,笔管缺陷自动化检测系统可以客观地检测笔管的缺陷,提高笔管生产效率,提升生产线的成品质量,具有较高的工程应用价值。 相似文献
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分区域分等级的印刷品缺陷检测方法 总被引:4,自引:4,他引:0
目的为了体现印刷品不同区域的重要性等级,提高印刷品缺陷检测的精度,提出了一种分区域分等级的印刷品缺陷检测方法。方法根据检测区域的特点和重要性不同,把印刷品分成不同的区域进行前景提取,并且设置不同的检测等级;对印刷品进行符合人眼视觉特性的缺陷识别,并对提取缺陷进行特征分析。结果分区域的缺陷检测可以实现不同区域的同时检测,在检测耗时、检测准确率及误检率上都优于不分区域的检测方法。结论基于分区域的印刷品缺陷检测方法能很好地满足印刷品质量检测的需求,提高印刷品缺陷检测的精度和效率。 相似文献
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高温结构陶瓷缺陷的激光扫描超声显微检测 总被引:1,自引:1,他引:0
本文介绍了激光扫描超声显微镜的工作原理和在陶瓷缺陷检测中的应用。讨论了从缺陷的声图像判断缺陷的大小、位置以及性质的方法。通过对各种陶瓷缺陷的检测实验,证实了利用高频(100 MHz)超声对检测陶瓷中<100μm 缺陷的可能性。 相似文献
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Scanning photoacoustic microscopy (SPAM) was applied to silicon nitride turbine hardware for purposes of detecting fabrication defects. SPAM traces in selected areas of complex-shaped turbine stator vanes were obtained and indicate that surface-crack detection of the order of tens of microns is possible. Means were devised to allow for multiple scans in areas previously inaccessible to other nondestructive techniques capable of detecting defects in the 25- to 100-µm range. The results show that SPAM is applicable to reaction-bonded silicon nitride turbine components and capable of detecting small surface-related defects. 相似文献
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Equations related to spatial statistics of defects and probability of detecting defects in one-dimensional components have been derived. The equations related to spatial statistics of defects allow to estimate the probability of existence of safe, defect-free zones between the defects in one-dimensional components. It is demonstrated that even for a moderate defect number densities, the probability of existence of clusters of two or more defects at a critically small distance is substantial and should not be neglected in calculations related to risks of failure. The formulae derived have also important application in reliability and risk assessment studies related to calculation of the probability of clustering of evens on a given time interval. It is demonstrated that while for large tested fractions from one-dimensional components, the failures are almost entirely caused by a small part of the largest defects, for small tested fractions almost all defects participate as initiators of failure. The problem of non-destructive defect inspection of one-dimensional components has also been addressed. A general equation has been derived regarding the probability of detecting at least a single defect when only a fraction of the component is examined. 相似文献
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We investigate the application of induction motor stator current spectral analysis (MCSA) for detection of rolling element
bearing damage from the outer raceway. In this work, MCSA and vibration analysis are applied to induction motor to detect
outer raceway defects in faulty bearings. Data acquisition, recording, and fast fourier transform (FFT) algorithms are done
by using the Lab VIEW programming language. Experimental results verify the relationship between vibration analysis and MCSA,
and identify the presence of outer raceway bearing defects in induction machines. This work also indicates that detecting
fault frequencies by motor currents is more difficult than detecting them by vibration analysis. The use of intensive resolution
FFT is recommended in MCSA for detecting faults easily. Reinstalling a faulty bearing can alter the characteristic frequencies
and it is difficult to compare results from different bearings or even from the same bearing in different installations. 相似文献
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Gu Wei Chu Jianxin 《IEEE transactions on instrumentation and measurement》2002,51(1):120-124
Based on analyzing the magnetic leakage feature of wire rope defects, the longitudinal resolved vector Bot of the defect leakage field is taken for the object to be tested. In order to detect the weak magnetic leakage field, a fluxgate sensor of single core and single winding is developed. Using the fluxgate, a new kind of transducer for testing defects of wire rope has been designed. The structure and interface circuit of the transducer are studied. The experimental results of detecting the LF and LMA defects of the wire rope are presented 相似文献
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基于图像配准的STN-LCD外观缺陷检测 总被引:2,自引:1,他引:1
提出了一种基于图像配准的超扭曲向列液晶显示器件(STN-LCD)的外观缺陷自动检测方法.该方法首先对标准模板图像做不均匀光照消除、二值化以及区域信息提取;然后通过控制点检测和仿射变换实现待检测图像和模板图像之间的配准;并利用各图形区域的灰度平均值和标准方差等统计信息,检测缺段、针孔等各类缺陷.为提高图像配准精度,进一步提出了有效控制点筛选方案以及混合插值方法.实验结果表明,该方法设计思路合理,缺陷检测正确率达到98.3%,可代替人眼实现对STN-LCD多种外观缺陷的快速、自动检测,满足实际应用需求. 相似文献
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Line-focusing electromagnetic acoustic transducers for the detection of slit defects 总被引:3,自引:0,他引:3
Ogi H Hirao M Ohtani T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(2):341-346
This paper describes the design principles of a line-focusing electromagnetic acoustic transducer (LF-EMAT) and the results of a feasibility test for detecting slit-type defects in metals. The LF-EMAT excites shear vertical (SV) elastic waves and focuses them to a line in a metal body. It consists of a permanent magnet block and a meanderline coil, whose spacing is continuously varied so that the excited SV waves become coherent on a focal line after traveling oblique paths. The measured directivity of generation and reception show a sharp peak at the designed focal line. The LF-EMATs are then applied to detecting slit defects in the bottom surface of steel blocks, on which the focal lines are located. Portions of the scattered defect signals are received by the same EMAT. When operated at 4 MHz, the LF-EMATs are capable of detecting slits deeper than 0.05 mm. The sensitivity decreases with liftoff and the LF-EMATs are usable with liftoff up to 0.6 mm. 相似文献
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针对风力发电机叶片人工检测低效,缺陷诊断难的问题,提出一种基于无人机与图像处理的风力发电机叶片缺陷识别方法。通过Halcon 12与Visual Studio 2015的联合开发,实现图像处理流程、检测结果输出以及缺陷回放等功能,包括相机标定、通过快速自适应加权中值滤波处理图像、动态阈值分割叶片图像缺陷特征,利用区域处理识别裂纹和砂眼等缺陷,并对缺陷进行分类与测量以及输出对叶片质量的分析报告等,实现风力发电机叶片表面缺陷的自动检测功能。通过实例验证了该方法在风力发电机叶片表面缺陷检测中的较高精确性与算法稳定性。 相似文献