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Laser additional material manufacturing defect online diagnosis method based on visual sensing

A technology of laser additive and diagnostic methods, applied in the directions of optical testing flaws/defects, additive manufacturing, additive processing, etc., can solve problems such as collapse, unsatisfactory forming structure performance, cracks, etc.

Active Publication Date: 2017-11-28
HARBIN INST OF TECH AT WEIHAI
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the research on the performance of metal laser additive manufacturing parts found that although the performance of parts can reach the corresponding standards and specifications of homogeneous materials in individual indicators, there is still a certain gap in general. The main reason is that additive manufacturing The inherent characteristics of the technical forming mechanism - the microscopic defects inside the workpiece caused by the "transient melting process", such as cracks, pores, slag inclusions, slump, etc.
Or due to actual production reasons such as technology, it is easy to cause problems such as insufficient bonding strength between bonding layers, inconsistent performance, etc., so that the performance of the formed structure cannot meet the requirements, thereby limiting the application of this technology

Method used

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  • Laser additional material manufacturing defect online diagnosis method based on visual sensing
  • Laser additional material manufacturing defect online diagnosis method based on visual sensing
  • Laser additional material manufacturing defect online diagnosis method based on visual sensing

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Experimental program
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Effect test

Embodiment 1

[0055] Such as Figure 5 As shown, this embodiment simulates the situation that the output power of the laser is changed to cause defects in additive manufacturing. The physical schematic diagram of the additive molding formed by metal laser additive manufacturing is as follows: Figure 5 As shown in (a), the molding layer is divided into a first area A, a second area B, and a third area C. Wherein the output power of the laser changes during the manufacturing process of the shaping layer in the second region B.

[0056] Through the above-mentioned online diagnosis method, the obtained time-domain diagram of the molten pool area changing with time is as follows: Figure 5 As shown in (b), the frequency domain map of the molten pool area is shown as Figure 5 As shown in (c), it can be seen that when the output power of the laser changes, the time domain curve of the molten pool area fluctuates or changes sharply from a relatively stable state, and there are obvious abnormal...

Embodiment 2

[0058] Such as Figure 6 As shown, this embodiment simulates the situation where the scanning speed of the additive processing head is changed to cause defects in additive manufacturing. The physical schematic diagram of the additive molding formed by metal laser additive manufacturing is as follows: Figure 6 As shown in (a), the molding layer is divided into the fourth area D, the fifth area E, and the sixth area F. The molding layers of the fourth area D and the sixth area F are added to the processing head during the manufacturing process. The scanning speed is 300 mm / min, and the scanning speed of the additive processing head is 0 mm / min during the manufacturing process of the forming layer of the fifth area E, and other parameters include that the output power of the laser is 1600 W, and the powder feeding rate is 13.4g / min, the protective gas flow rate is 10L / min.

[0059] Through the above-mentioned online diagnosis method, the obtained time-domain diagram of the mol...

Embodiment 3

[0061] Such as Figure 7 As shown, this embodiment simulates the situation that the flow rate of the shielding gas is changed to cause defects in additive manufacturing. The physical schematic diagram of the additive molding formed by metal laser additive manufacturing is as follows: Figure 7 As shown in (a), the molding layer is divided into the seventh area G, the eighth area H and the ninth area I, and the protective gas flow rate of the molding layer in the seventh area G and the ninth area I during the manufacturing process is 15 L / min, while the protective gas flow rate of the molding layer in the eighth region H during the manufacturing process is 0 L / min, other parameters include the output power of the laser is 1600 W, and the scanning speed of the additive processing head is 600 mm / min, the powder feeding rate is 13.4g / min.

[0062] Through the above-mentioned online diagnosis method, the obtained time-domain diagram of the molten pool area changing with time is ...

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Abstract

The invention provides a laser additional material manufacturing defect online diagnosis method based on visual sensing. The method comprises the following steps of collecting a molten pool analog image signal by a CCD camera in real time; converting the molten pool analog image signal into a digital image signal by an image collecting card and importing the digital image signal into a computer; performing real-time image processing on the digital image signal through the computer so as to obtain a time domain picture of the molten pool area; performing short-time Fourier transform on the time domain picture so as to obtain a frequency domain picture of the molten pool area; judging whether the molten pool area suddenly fluctuates or changes or not on the basis of the time domain picture of the molten pool area; if not, judging that no manufacturing defect exists; if so, judging whether the obvious abnormal fluctuation occurs in the frequency domain picture of the molten pool area or not in the sudden fluctuation or change time period of the molten pool area; if so, judging that the macroscopic manufacturing defect exists; if not, judging that the non-macroscopic manufacturing defect exists. The method can be used for judging the generation of the defects, the occurrence moment and the defect types in the laser additional material manufacturing process.

Description

technical field [0001] The invention relates to the field of metal laser additive manufacturing, in particular to an online diagnosis method for defects in laser additive manufacturing based on visual sensing. Background technique [0002] Laser additive manufacturing technology has unique advantages such as complex formed parts, optimized structure, excellent performance, and a wide range of processed materials. It can realize gradient functions, high degree of flexibility, and short manufacturing cycle. In terms of cost, it is superior to casting and forging technology, and it is an advanced manufacturing technology with high quality, material saving, low cost and no pollution. However, the research on the performance of metal laser additive manufacturing parts found that although the performance of parts can reach the corresponding standards and specifications of homogeneous materials in individual indicators, there is still a certain gap in general. The main reason is th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/88G01N21/95G01N21/84B22F3/105
CPCG01N21/84G01N21/8851G01N21/95G01N2021/8887G01N2021/8411B22F10/00B22F10/36B22F10/366B22F10/25B22F12/50B22F12/90B22F10/322Y02P10/25
Inventor 陈波姚永臻王文康檀财旺黄煜华陈毅松冯吉才
Owner HARBIN INST OF TECH AT WEIHAI
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