Method for calibrating CT measurement data by using profile measurement data

A technology for measuring data and shape, applied in the field of industrial CT non-destructive testing, can solve problems such as difficult traceability and complex sources of measurement errors, and achieve the effects of wide applicability, improved accuracy and reliability, and easy access

Active Publication Date: 2021-06-29
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0010]Aiming at the problems of complex sources of industrial CT measurement errors and difficult traceability, the present invention provides a general method for calibrating CT measurement data using profile measurement data, using profile measurement The advantages of high precision and high reliability of the data can not only reliably calibrate the CT measurement results, but also not be affected by the different parameters of the CT measurement system

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  • Method for calibrating CT measurement data by using profile measurement data

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Embodiment 1

[0028] Embodiment 1: For a titanium alloy 3D printed part, the part has external cylindrical features, and the diameter of an inner flow channel is measured by conventional focus industrial CT, and the method provided by the present invention is applied to perform the following steps:

[0029] Step 1: Select a vernier caliper with a nominal measurement accuracy of ±0.02mm, which is known to be higher than the measurement accuracy of the conventional focal industrial CT used. For the titanium alloy 3D printed part, use a vernier caliper to measure an external cylinder within its scanning area Diameter, the type of this geometric dimension is an entity class, denoted as S 1 ;

[0030] Step 2: Perform CT scan reconstruction on the part to obtain a tomographic image;

[0031] Step 3: Carry out image segmentation on the tomographic image to obtain CT point cloud data;

[0032] Step 4: According to the CT point cloud data, measure the geometric size of the corresponding part in st...

Embodiment 2

[0038] Embodiment 2: For a high-temperature alloy precision casting part, the part has the features of external cylinder, round hole and boss, and adopts small-focus industrial CT to measure the position of 9 round holes inside it, and applies the method provided by the present invention to perform the following step:

[0039] Step 1: Select a three-coordinate measuring machine with a nominal measurement accuracy of (3.7+L / 100) μm. It is known that the accuracy is higher than the small-focus industrial CT measurement accuracy used. For the high-temperature alloy precision casting parts, use three-coordinate The measuring machine measures 3 geometric dimensions within its scanning area, including a cylindrical diameter S 1 , a boss thickness S 2 , a circular hole diameter E 1 , where S 1 and S 2is the entity class size, E 1 is the cavity size;

[0040] Step 2: Perform CT scan reconstruction on the part to obtain a tomographic image;

[0041] Step 3: Carry out image segme...

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Abstract

The invention provides a method for calibrating CT measurement data by using profile measurement data, and belongs to the technical field of industrial CT nondestructive testing. In allusion to the problems that industrial CT measurement errors are complex in source and difficult in traceability, according to the actual situation that appearance measurement instruments are multiple in variety and easy to obtain, by means of the characteristics of high precision and high reliability of appearance measurement data, the measurement deviation of CT is obtained by measuring the geometric dimensions of the same part of parts, and then the CT measurement precision is improved by adopting a mode of firstly measuring and then calibrating or firstly calibrating and then measuring. The method does not need to develop special standard parts, is not influenced by factors such as part materials, structures and sizes, is wide in applicability, and can effectively improve the precision and reliability of CT measurement results.

Description

technical field [0001] The invention relates to a method for calibrating CT measurement data by using shape measurement data, and belongs to the field of industrial CT nondestructive testing. Background technique [0002] CT (Computed Tomography) is a computerized tomography imaging technology, which can obtain clear and intuitive tomographic images by scanning and reconstructing the detected object without destroying it. With its excellent three-dimensional imaging capabilities and internal and external structure detection capabilities, CT technology is expanding from the traditional field of non-destructive testing to the field of geometric coordinate measurement. [0003] The geometric measurement of industrial CT generally includes two methods: grayscale-based measurement and point cloud-based measurement. The grayscale-based measurement is directly measured and calculated on the tomographic image according to a certain grayscale threshold, and the measurement accuracy a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B15/00G01B15/04
CPCG01B15/00G01B15/04G01B21/042
Inventor 黄魁东张欣
Owner NORTHWESTERN POLYTECHNICAL UNIV
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