Method and device for synchronously observing visual signal and particle signal of plume

Abstract

The invention provides a plume visual signal and particle signal synchronous observation method and device, and belongs to the technical field of laser material processing.The plume visual signal and particle signal synchronous observation device comprises a to-be-processed material, a processing area is arranged on the upper surface of the to-be-processed material, and a processing laser is arranged above the processing area; a photoelectric detector and a detection laser are arranged on the two sides of the machining area respectively, a signal amplifier is connected to one side of the detection laser, the signal amplifier and the photoelectric detector are both connected with an oscilloscope, a high-speed camera is further arranged on one side of the detection laser, and the high-speed camera and the oscilloscope are both connected with a computer. The synchronous observation method and device for the visual signal and the particle signal of the plume have the advantages of being simple in structure, small in size, easy to adjust, free of external interference, low in cost and the like, and synchronous observation of the visual signal and the particle signal of the plume can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of laser material processing technology, and in particular to a method and device for synchronously observing visual signals and particle signals of a feather. Background Art

[0002] Compared with traditional laser processing technology, high-power fiber laser processing technology has shown significant advantages such as excellent beam quality, high energy density and high electro-optical conversion efficiency. Combining fiber laser technology with intelligent manufacturing can promote more efficient, precise and flexible production methods, injecting more innovative vitality and development opportunities into the manufacturing industry.

[0003] During the laser processing, plume is one of the most intuitive physical phenomena in laser processing at a wavelength of 1 micron. It appears as a hot luminous body above the keyhole, which is composed of liquid particles and high-temperature gas. The dynamic behavior of plume is closely related to the laser processing process and is the most intuitive external manifestation in fiber laser processing. By observing the dynamic behavior of plume, we can conduct real-time quality monitoring of the processing process, which lays a solid foundation for the intelligentization of fiber laser processing.

[0004] At present, the monitoring methods for plume mainly include visual signals, acoustic signals, optical signals and electrical signals. In the research of plume, significant progress has been made in morphological observation, temperature diagnosis and the influence of plume on the processing process. However, in complex industrial environments, the dynamic behavior of plume is easily disturbed by external factors such as strong light, protective airflow, noise, etc., which affects the quality of signal collection and even causes signal distortion.

[0005] Although the particles in the plume, as its main component, are relatively unaffected by the above factors, the luminescence of the plume mainly comes from its gaseous part. In addition, the diameter of the particles in the plume ranges from several nanometers to several micrometers, which makes it extremely difficult to achieve in situ measurement of particle size or movement speed through high-speed photography. Therefore, a method to characterize the dynamic behavior of the plume based on the particle signals in the plume has not yet been established, that is, the connection between the particle signals and the visual signals of the plume has not been clearly defined.

[0006] In order to overcome these limitations, the present invention proposes an innovative multi-signal synchronous observation method, which combines the particle signal in the plume with the visual signal of the plume. This method can not only accurately correspond the particle signal with the plume image, thereby more accurately characterizing the dynamic behavior of the plume; it can also combine the advantages of both to obtain a more comprehensive and real plume signal, thereby providing strong support for the monitoring of the laser intelligent processing process. Summary of the invention

[0007] The purpose of the present invention is to provide a method and device for synchronous observation of the visual signal and particle signal of the feather, which has the advantages of simple structure, small size, easy adjustment, no need for external interference, low cost, etc., and can realize the synchronous observation of the visual signal and particle signal of the feather.

[0008] To achieve the above-mentioned purpose, the present invention provides a synchronous observation device for the visual signal and particle signal of Yuhui, including a material to be processed, a processing area is arranged on the upper surface of the material to be processed, a processing laser is arranged above the processing area, photoelectric detectors and detection lasers are respectively arranged on both sides of the processing area, a signal amplifier is connected to one side of the detection laser, the signal amplifier and the photoelectric detector are both connected to an oscilloscope, a high-speed camera is also arranged on one side of the detection laser, and the high-speed camera and the oscilloscope are both connected to a computer.

[0009] Preferably, the processing laser emits a processing laser beam vertically to the processing area, and the angle between the processing laser beam and the detection laser beam emitted by the detection laser is 10 to 90°; the angle between the detection laser beam and the processing direction is 0 to 180°; the distance between the detection laser beam and the keyhole is 0.1 to 100 mm.

[0010] Preferably, the shooting frame rate of the high-speed camera is 1000-50000 frames / s, the height of the high-speed camera is flush with the surface of the material to be processed, and the shooting direction is perpendicular to the processing direction of the processing laser.

[0011] Preferably, the photodetector is a silicon photodetector having a response wavelength range of 200-1100 nm.

[0012] Preferably, the wavelength of the detection laser beam is 0.1-20 μm, and the spot diameter is 0.1-8 mm.

[0013] Based on the above-mentioned synchronous observation device of the visual signal and the particle signal of the feather, the present invention also provides a synchronous observation method of the visual signal and the particle signal of the feather, comprising the following steps: Step S1, connecting the detection laser and the photodetector to an oscilloscope, using the photodetector as a medium for synchronous observation, using the detection laser to measure the characteristics of the particles inside the plume, and using a high-speed camera to record the visual signal of the plume; Step S2: When the processing starts, the detection laser, photodetector and high-speed camera are started simultaneously; Step S3, when a particle passes through the detection laser beam of the detection laser, part of the detection laser beam is reflected by the particles in the plume back to the detection laser cavity to produce a self-mixing effect, and after the photoelectric signal is converted and an interference signal is generated, the time when the first particle signal is generated is determined according to the time difference between the two electrical signals of the detection laser and the photodetector; Then, according to the set shooting frame rate of the high-speed camera, the frame number of the corresponding moment is found in the feather glow picture taken by the high-speed camera, so as to realize its correspondence with the first particle signal and determine the time interval between the first frame picture of the feather glow and the first particle signal; Step S4: According to the shooting frame rate of the high-speed camera and the sampling rate of the oscilloscope, the synchronous observation of the feather visual signal and the particle signal is achieved.

[0014] Therefore, the present invention adopts the above-mentioned method and device for synchronously observing the visual signal and particle signal of the feather glow, and the beneficial technical effects are as follows: (1) The present invention can realize in-situ real-time synchronous observation of the plume visual signal and the plume particle signal. Compared with the existing plume observation method, the present invention can establish the connection between the plume particle signal and the plume dynamic behavior, and determine the correspondence between the plume particle signal and the laser processing process, while avoiding the influence of the processing environment on information collection.

[0015] (2) The present invention can combine the advantages of both to obtain a more comprehensive plume signal, thereby obtaining real processing information and promoting the development of laser intelligent processing process monitoring.

[0016] (3) The present invention has the advantages of simple structure, small size, easy adjustment, no need for external interference, no influence of detection laser power fluctuation, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a synchronous observation device for visual signals and particle signals of feather glow according to the present invention; Figure 2 The feather particle signal and photoelectric detection signal of the same processing process obtained in the experiment; Figure 3 The plume morphology was observed by continuous high-speed video observation obtained in the experiment; Figure 4 This is the correspondence between the experimentally obtained plume image and the particle signal.

[0018] Reference numerals 1. Laser processing plume; 2. Processing area; 3. High-speed camera; 4. Detection laser power supply; 5. Detection laser; 6. Signal amplifier; 7. Photodetector; 8. Oscilloscope; 9. Computer; 10. Photodetection signal; 11. Plume particle signal; 12. Bottom swinging plume; 13. Processing laser; 14. Processing laser beam. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0020] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0021] Embodiment 1 like Figure 1 As shown, it is a structural schematic diagram of a synchronous observation device for visual signals and particle signals of feather glow of the present invention, including a material to be processed, a processing area 2 is arranged on the upper surface of the material to be processed, a processing laser 13 is arranged above the processing area 2, a photoelectric detector 7 and a detection laser 5 are respectively arranged on both sides of the processing area 2, a signal amplifier 6 is connected to one side of the detection laser 5, the signal amplifier 6 and the photoelectric detector 7 are both connected to an oscilloscope 8, a high-speed camera 3 is also arranged on one side of the detection laser 5, and the high-speed camera 3 and the oscilloscope 8 are both connected to a computer 9.

[0022] The processing laser 13 emits a processing laser beam 14 vertically toward the processing area 2 and generates a laser processing plume 1 .

[0023] In this embodiment, the processing laser 13 is an IPG YLS-6000 fiber laser with a wavelength of 1.07 μm, the processing laser beam 14 is transmitted through an optical fiber with a core diameter of 200 μm, the focal length of the output coupling collimator is 200 mm, and after focusing through a lens with a focal length of 300 mm, a focused spot with a diameter of 0.32 mm is obtained. The material to be processed used in the experiment is low carbon steel with a size of 100 mm × 50 mm × 10 mm. The processing parameters are: laser power of 5 kW and processing speed of 2 m / min.

[0024] High-speed camera 3 uses the American PHOTRON Fastcam Mini UX100 color high-speed camera, and the fixed frame rate during shooting is 10000 frames / s.

[0025] The detection laser 5 is a semiconductor laser with a wavelength of 1.31 μm and a power of 500 μW. The sampling rate is set to 5 MSa / s, the collection height is 5 mm, and the detection direction is perpendicular to the scanning processing direction of the processing laser beam 14 .

[0026] The photodetector 7 is a Dsi300 photodetector with a response wavelength range of 300-1100 nm. The response time of the photodetector 7 to the optical signal is in the order of hundreds of nanoseconds, which is much smaller than the feather oscillation period (about 0.5 ms), and can meet the needs of synchronous observation.

[0027] Oscilloscope 8 is an RTB2004 oscilloscope produced by R&S of Germany, and its maximum real-time sampling rate is 2.5GSa / s. In the synchronous observation test, after the detection laser beam of the detection laser 5 passes through the plume, part of the light is reflected back to the detection laser cavity by the particles in the plume to produce a self-mixing effect and a new resonance, and then the photoelectric signal is converted and amplified by the signal amplifier 6, and then connected to the photodetector 7 to the same oscilloscope 8 for synchronous triggering, and the laser processing process is recorded by the high-speed camera 3 at the same time.

[0028] At the moment of laser processing, high-power processing laser-induced particle spatter and laser-induced vaporization occur almost simultaneously. At this time, the photodetector 7 and the high-speed camera 3 will collect strong light signals, and the photodetector 7 will convert the light signals into electrical signals that suddenly rise. Figure 2 It can be seen that the photoelectric detection signal 10 and the plume particle signal 11 are generated almost simultaneously, and the time difference between the two is less than 5μs, which is much smaller than one cycle of the bottom swing plume (about 0.5ms). In the synchronous observation experiment, it can be approximately considered that the two occur at the same time. The rising electrical signal generated at this time also corresponds to the first frame of processed image with light taken by the high-speed camera 3. Therefore, the time difference between the photoelectric detection signal and the plume particle signal in the experiment is negligible. To obtain the corresponding image of the plume particle signal and the plume dynamics at any time, it is only necessary to calculate the time interval T between the nth particle signal and the first particle signal, and then find the plume image after the first frame of light has been emitted for T time in the image taken by the high-speed camera 3. This image corresponds to the nth particle signal.

[0029] From the images taken by the high-speed camera 3, it can be seen that the bottom plume will swing irregularly periodically (bottom swing plume 12), such as Figure 3 As shown. The image taken by the high-speed camera 3 whose detection direction is perpendicular to the scanning direction is matched with the signal of the feather particles. It is found that when the bottom swing feather is in a vertical state, the signal intensity of the feather particles and the number of interference fringes are relatively large, as shown in Fig. Figure 4 This phenomenon indicates that when the bottom swing plume erupts in the opposite direction of the high-power fiber laser beam, there are relatively more particles in the detection area of ​​the detection laser, so the signal induced by the particles carried in the eruption plume is stronger.

[0030] It is worth noting that the contents not elaborated in detail in the present invention are all prior art and are well known to those skilled in the art.

[0031] Therefore, the present invention adopts the above-mentioned method and device for synchronous observation of the visual signal and particle signal of the feather glow, which has the advantages of simple structure, small size, easy adjustment, no need for external interference, and low cost, and can realize the synchronous observation of the visual signal and particle signal of the feather glow.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A synchronous observation device for visual signals and particle signals of feathers, characterized in that: It includes a material to be processed, a processing area is arranged on the upper surface of the material to be processed, a processing laser is arranged above the processing area, a photoelectric detector and a detection laser are arranged on both sides of the processing area, a signal amplifier is connected to one side of the detection laser, the signal amplifier and the photoelectric detector are connected to an oscilloscope, a high-speed camera is also arranged on one side of the detection laser, and the high-speed camera and the oscilloscope are connected to a computer.

2. The synchronous observation device for visual signal and particle signal of feather glow according to claim 1, characterized in that: The processing laser emits a processing laser beam vertically to the processing area, and the angle between the processing laser beam and the detection laser beam emitted by the detection laser is 10 to 90 degrees; the angle between the detection laser beam and the processing direction is 0 to 180 degrees; the distance between the detection laser beam and the keyhole is 0.1 to 100 mm.

3. The synchronous observation device for visual signal and particle signal of feather glow according to claim 2, characterized in that: The shooting frame rate of the high-speed camera is 1000~50000 frames / s. The height of the high-speed camera is flush with the surface of the material to be processed, and its shooting direction is perpendicular to the processing direction of the processing laser.

4. The synchronous observation device for visual signal and particle signal of feather glow according to claim 3, characterized in that: The photodetector is a silicon photodetector with a response wavelength range of 200~1100nm.

5. The synchronous observation device for visual signal and particle signal of feather glow according to claim 4, characterized in that: The wavelength of the detection laser beam is 0.1~20μm, and the spot diameter is 0.1~8mm.

6. A method for synchronously observing the visual signal and particle signal of a feather, characterized in that: The following steps are involved: Step S1, connecting the detection laser and the photodetector to an oscilloscope, using the photodetector as a medium for synchronous observation, using the detection laser to measure the characteristics of the particles inside the plume, and using a high-speed camera to record the visual signal of the plume; Step S2: When the processing starts, the detection laser, photodetector and high-speed camera are started simultaneously; Step S3, when a particle passes through the detection laser beam of the detection laser, the detection laser beam is reflected by the particles in the plume back to the detection laser cavity to produce a self-mixing effect, and after the photoelectric signal is converted and an interference signal is generated, the time when the first particle signal is generated is determined according to the time difference between the two electrical signals of the detection laser and the photodetector; Then, according to the set shooting frame rate of the high-speed camera, the frame number of the corresponding moment is found in the feather glow picture taken by the high-speed camera, so as to realize its correspondence with the first particle signal and determine the time interval between the first frame picture of the feather glow and the first particle signal; Step S4: According to the shooting frame rate of the high-speed camera and the sampling rate of the oscilloscope, the synchronous observation of the feather visual signal and the particle signal is achieved.

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