Automatic optic inspection method for surface defects of metal cylindrical workpieces

An automatic optical inspection and metal cylinder technology, which is applied in image data processing, instruments, calculations, etc., can solve the problems of many human interference factors, low detection efficiency, and reduced product performance, so as to realize automatic optical defect detection and overcome poor illumination. The effect of reducing the misjudgment rate

Inactive Publication Date: 2014-11-19
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

Due to the influence of casting technology, processing technology and other factors, metal cylindrical workpieces usually have different types of defects such as indentation, holes, cracks, dust inclusions, surface stains, rust, scratches, wrinkles, etc. These defects seriously reduce the Performance of subsequent products
[0003] At present, manual visual inspection is mostly used for metal cylindrical workpieces. Manual inspection is subject to many human interference factors, low detection efficiency, and lack of scientificity and standardization.

Method used

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  • Automatic optic inspection method for surface defects of metal cylindrical workpieces
  • Automatic optic inspection method for surface defects of metal cylindrical workpieces
  • Automatic optic inspection method for surface defects of metal cylindrical workpieces

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Embodiment Construction

[0027] The specific implementation steps are illustrated in conjunction with the accompanying drawings:

[0028] Step 1: First, the linear array CCD is used to collect the unfolded image on the surface of the metal cylindrical workpiece, such as Pic 4-1 , and grayscale the image.

[0029] Step 2: The local binary pattern is defined in a circular area with a radius of R (R>0), and P pixels are evenly distributed on the circumference. The texture of the central pixel in this neighborhood is recorded as T, and T can use this area P The relational expression of +1 pixel is defined, and the defined texture operator is not affected by the monotonous change of image grayscale, so the sign of the difference is used for calculation:

[0030] T=t(S(g 0 -g c ), S(g 1 -g c )...,S(g P-1 -g c ))

[0031] S ( x ) = 1 x ...

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Abstract

The invention provides an automatic optic inspection method for surface defects of metal cylindrical workpieces and belongs to the automatic optic inspection methods. The automatic optic inspection method is particularly suitable for detecting surface defects of special metal cylindrical workpieces and comprises the following steps: a linear array CCD acquires the unrolled images of a metal cylindrical workpiece, the local binary pattern (LBP) and the local variance (LVAR) are combined, that is, the image variance intensity serves as the weight value to adjust the local texture extraction and measurement result of the LBP, not only the LBP texture space structure mode but also the texture intensity contrast mode is drawn into consideration, finally, the photoelectric image fault features of metal cylinders are accurately extracted, the sizes, the positions, the ranges, the severities and the like of the defects are determined, and the automatic intelligent detection of the workpiece production quality is realized. Therefore, nonuniform lighting caused by the metal materials of the workpieces per se is avoided, the accuracy in detecting tiny defects is improved, the misjudgement rate is lowered, and automatic optic inspection of the metal cylindrical workpieces is achieved.

Description

technical field [0001] The invention belongs to an automatic optical detection method, and is especially suitable for the detection of apparent defects of metal cylinder special workpieces. Background technique [0002] Metal cylindrical workpieces are indispensable raw materials in many industries, and their apparent quality has become one of the important indicators of domestic and foreign market competition. Due to the influence of casting technology, processing technology and other factors, metal cylindrical workpieces usually have different types of defects such as indentation, holes, cracks, dust inclusions, surface stains, rust, scratches, wrinkles, etc. These defects seriously reduce the performance of subsequent products. [0003] At present, manual visual inspection is mostly used for metal cylindrical workpieces. Manual inspection is subject to many human interference factors, low detection efficiency, and lack of scientificity and standardization. Contents of ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00
Inventor 刘霖张静刘娟秀何岗谢煜杜晓辉袁阳杨先明叶玉堂刘永
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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