An online calibration method for emissivity of mid-infrared thermal imager in additive manufacturing
An infrared thermal imager and additive manufacturing technology, which is applied in the field of image-based temperature monitoring and additive manufacturing online monitoring, can solve the problems of workpiece emissivity changing with the environment, difficult to calibrate, etc., and achieves stable and reliable method and processing speed. Fast, low environmental impact results
Active Publication Date: 2021-06-08
DALIAN UNIV OF TECH
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[0005] Aiming at the deficiencies of existing methods, the present invention provides an online calibration method for infrared thermal imager emissivity in the additive manufacturing process. The method is based on image detection technology and has good real-time performance, fast visual signal processing speed, good accuracy, and no Affected by processing materials and the environment, etc., it effectively solves the problem that the emissivity of workpieces changes with the environment and is difficult to calibrate in additive manufacturing, thereby effectively improving the accuracy of process temperature monitoring and providing a basis for the accuracy of additive manufacturing process monitoring, The quality of the final product is guaranteed
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[0056] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not constitute a conflict with each other.
[0057] In the additive manufacturing experiment, the temperature field is an important physical field, which has a great influence on the quality and performance of the processed products. Accurate extraction of temperature information is very important for the additive manufacturing to produce high-quality parts. Due to the extremely high temperature of the molten pool during processing, the n...
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Abstract
The invention discloses an online calibration method for the emissivity of a mid-infrared thermal imager in additive manufacturing, which belongs to the technical field of additive manufacturing online monitoring. On the basis of the original additive manufacturing and its online monitoring system, a side-axis thermal imager and an online image processing unit are added, and the side-axis thermal imager is located on the side of the laser head and the substrate. First, the visual image of the molten pool is extracted, and a rectangle is circumscribed to the molten pool; the whole processing process is monitored by a paraxial infrared thermal imager, and the infrared image is extracted. Secondly, the actual molten pool length L of the visual image and the actual molten pool length l of the infrared image are obtained by reducing the size of the extracted visual image and infrared image respectively. Finally, compare L with l, and adjust the emissivity of the infrared thermal imager to make them equal, then the emissivity is the actual emissivity. The invention can perform online calibration on the emissivity of the infrared thermal imager in the additive manufacturing process, has high processing speed, stable and reliable method, less environmental influence, high degree of integration and strong applicability.
Description
technical field [0001] The invention belongs to the technical field of on-line monitoring of additive manufacturing, relates to an online calibration method for the emissivity of a mid-infrared thermal imager in additive manufacturing, and is also applicable to other image-based temperature monitoring fields. Background technique [0002] Additive manufacturing technology is an advanced manufacturing technology, which is mainly used in direct forming of parts, surface modification, repair of high-end parts and other fields. At present, the additive manufacturing technology of metals, alloys and metal matrix composites is facing challenges such as poor quality reliability and low production repeatability, and its dimensional accuracy and internal defects affect the popularization and application of this technology. Additive manufacturing is a multi-physics coupling process, in which the temperature field is a physical field that has an important impact on product quality. ...
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IPC IPC(8): G01J5/00
CPCG01J5/00G01J5/80
Inventor 刘伟嵬王灏颜昭睿唐梓珏王怡文王振秋李涛刘淑杰张昭
Owner DALIAN UNIV OF TECH