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Method for evaluating surface detects of small-sized workpieces and flow for detecting unqualified workpieces

A technology for small workpieces and workpiece surfaces, applied in the direction of optical testing flaws/defects, etc., can solve the problems of difficulty in evaluating workpieces, increasing costs, and the detection quality is greatly affected by human factors. The effect of low detection rate

Active Publication Date: 2012-02-15
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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Problems solved by technology

However, most of the above-mentioned detection methods have deficiencies and cannot be popularized and applied in the industry. For example, the artificial visual inspection method has low detection efficiency, the detection quality is greatly affected by human factors, and it will increase the cost. Due to the limitation of the principle, the detection method is mainly used in the defect detection of ultra-micro cracks, and it is difficult to evaluate workpieces with multiple defects; the eddy current detection technology is suitable for the detection of large plates

Method used

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  • Method for evaluating surface detects of small-sized workpieces and flow for detecting unqualified workpieces
  • Method for evaluating surface detects of small-sized workpieces and flow for detecting unqualified workpieces
  • Method for evaluating surface detects of small-sized workpieces and flow for detecting unqualified workpieces

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Embodiment 1

[0036] The surface defect types of small workpieces are shown in Fig. 1, Figure 1a to Figure 1e Schematic diagrams of five types of defects, namely missing corners, dropped edges, abnormal shapes, pockmarks and cracks.

[0037] figure 2 It is an evaluation method for the surface defects of the above-mentioned small workpieces, which specifically includes the following steps:

[0038] Step 1: Under the coaxial light source, use an industrial camera to capture the grayscale image of the surface of the small workpiece. The surface size of the workpiece is 4mm×3.5mm, and the resolution of the grayscale image is 640×512. Select a 5×5 template for the grayscale image Perform median smoothing filtering to obtain the filtered image; in order to locate the surface area of ​​the workpiece, the maximum inter-class variance method is used to calculate the optimal threshold for image segmentation, and threshold segmentation is performed on the filtered image, which is an adaptive thresho...

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Abstract

The invention discloses a method for evaluating surface detects of small-sized workpieces. The method comprises the following steps of: acquiring surface images of small-sized workpieces under a specific light source with an industrial camera; detecting various defects such as unfilled corners, edge dropping, abnormity, pockmarks, cracks and the like of the small-sized workpieces based on image processing and profile analyzing methods; evaluating the severity and quantity of defects such as the unfilled corners, the edge dropping and the like of the small-sized workpieces by adopting a convexdefect evaluating parameter and a method for combining the convex defect evaluating parameter with a linearity evaluating parameter; and evaluating the degrees of the pockmark and crack defects with a threshold value segmentation method based on dimensional histogram statistic and the ratio of pockmark pixels. Based on the evaluation, the invention further provides a flow for detecting surface-unqualified workpieces. The flow has low false detecting rate, high detecting speed and wide application range, can meet the online detection requirement of the small-sized workpieces, and is suitable for detecting surface defects of various small-sized workpieces.

Description

technical field [0001] The invention relates to the technical field of surface defects of small workpieces, in particular to a method for evaluating surface defects of small workpieces and a process for detecting surface unqualified workpieces using the evaluation method. Background technique [0002] Surface defects are an important factor affecting the surface quality of small workpieces, directly affecting the appearance and performance of the final product. For example, on the one hand, the surface defects of small permanent magnet workpieces affect the surface magnetic distribution and uniformity of magnetic properties of permanent magnet materials that magnetic material users are concerned about, and on the other hand, they mainly affect the determination of the corrosion resistance of permanent magnet materials. Important characteristic of magnet life. The surface defects of small mechanical parts seriously affect their mechanical properties and product appearance. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/88
Inventor 吴亮王欣刚庄克成王志坚
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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