High-resolution spectrum-based sub-atmosphere laser welding penetration on-line detection system and detection method thereof

Abstract

The present application belongs to the technical field of online detection of laser welding quality, and particularly relates to a sub-atmosphere laser welding penetration online detection system based on high-resolution spectroscopy and a detection method thereof. Laser generated by a laser (1) is emitted by a focused laser gun head (2) to act on a workpiece to be welded (3). The laser gun head (2) is located inside a sub-atmosphere test cabin (5), and the workpiece to be welded (3) is placed on a work platform (4) inside the sub-atmosphere test cabin (5). The movement of the workpiece to be welded (3) during the welding process is realized by driving a motor of the work platform (4) inside the sub-atmosphere test cabin (5). A variable focusing lens (8) is installed at the input end of a high-resolution spectrometer (6). A slit (7) exists between the variable focusing lens (8) and the high-resolution spectrometer (6). The high-resolution spectrometer (6) is connected to a data analysis processing unit through a nanosecond enhanced CCD detector (9). The present application solves the technical blank problem existing in the sub-atmosphere laser welding penetration detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of online detection of laser welding quality, and particularly relates to a sub-atmospheric laser welding penetration online detection system based on high-resolution spectrum and a detection method thereof. BACKGROUND

[0002] In recent years, industrial lasers have developed rapidly, and high-power industrial fiber lasers have entered the era of ten-kilowatt. The stability and maximum output power of the laser are constantly improved, and laser welding technology has become one of the mainstream technologies for advanced connection manufacturing in various engineering fields. With the continuous improvement of welding thickness, quality, efficiency and other requirements, traditional laser welding technology is also undergoing innovation and development. In recent years, researchers have generally found that changing the laser welding environment from the normal pressure environment (101kPa) to the sub-atmospheric environment (<101kPa) can obtain high-quality deep penetration welds with a large depth-width ratio similar to vacuum electron beam welding, and the laser energy utilization rate is greatly increased. At the same time, the sub-atmospheric welding method needs to reach an environment pressure much lower than electron beam welding, and the welding process does not exist radiation, has strong flexible processing capacity, and will play an important role in the welding manufacturing of thick-walled components in key fields such as aerospace and marine engineering.

[0003] The common laser welding seam penetration detection method in the normal pressure environment is generally divided into offline and online detection. Among them, the offline direct detection is the most widely used and has the lowest cost. After the experimental plate is welded, the researchers take the metallographic sample and macro detection of the welded joint by destructive method to obtain the weld penetration characteristics and other information. However, this method is complicated and belongs to destructive detection, and can only be used for pre-welding test on the sample plate and detection of the penetration under the relevant welding parameters, which has significant condition limitations. Compared with the online detection, the penetration online detection generally adopts indirect non-contact measurement method, which belongs to non-destructive detection. At present, it mainly includes coherent light method and thermal excitation signal extraction method. In the coherent light method, two beams of near-infrared laser with the same frequency and wavelength are divided into two parts, which are respectively shot on the bottom of the keyhole and the surface of the workpiece. Due to the difference in transmission distance, the light beams will interfere after being reflected back to the sensor, and the phase difference will appear. After calculation, the keyhole depth (which is approximately equal to the weld penetration) can be solved. The thermal excitation signal extraction method generally uses high-definition coaxial monitoring equipment to obtain the keyhole mesoscopic detection signal, and then associates the keyhole mesoscopic signal with the weld penetration characteristics to realize the online detection in the welding process. However, whether it is the coherent light method or the thermal excitation signal extraction method, the detection scale and precision of the penetration are limited, and the detection data are relatively accurate only when the penetration is less than 10 mm. The main reasons for this phenomenon are as follows: first, during the welding process, with the increase of laser power, a large amount of spatter, metal vapor, photo plasma and other substances will be sprayed out of the keyhole, and with the increase of laser power, the keyhole fluctuation becomes more and more violent, and the penetration instability increases sharply, which seriously interferes with the signal transmission of the detection light; second, with the increase of the welding penetration, the keyhole presents the trend of wide at the top and narrow at the bottom, and with the welding moving forward, the spatial size of the keyhole exists the phenomenon of backward inclination, which hinders the extraction of the characteristic signal at the bottom of the keyhole. At this time, the coherent light method and the thermal excitation signal extraction method cannot effectively detect the keyhole depth. These factors limit the application of the existing online detection method in the high-power deep penetration welding process.

[0004] The above factors have a great influence on the existing detection technology, and the main technical problems are as follows: 1. The offline direct detection will damage the welding structure, 2. The online measurement of the deep penetration welding in the normal pressure environment is seriously interfered by the metal vapor / plasma and other substances, and the stability of the deep penetration keyhole is poor, and the spatial size is not easy to realize the signal extraction, which limits the effective scale and precision of the existing method, 3. There is no public data report on the laser welding penetration detection technology in the sub-atmosphere environment. SUMMARY

[0005] The present application provides a kind of sub-atmosphere laser welding penetration online detection system and its detection method based on high-resolution spectrum, to solve the technical blank problem of the existing sub-atmosphere laser welding penetration detection.

[0006] The present application is realized by the following technical solutions:

[0007] A kind of sub-atmosphere laser welding depth online detection system and detection method based on high resolution spectrum, the system includes welding unit and data acquisition unit and data analysis processing unit,

[0008] The welding unit includes laser 1, focused laser gun head 2, welding workpiece 3, motion platform 4 and sub-atmosphere test cabin 5,

[0009] The laser generated by the laser 1 is emitted by the focused laser gun head 2 and acts on the workpiece 3 to be welded, the laser gun head 2 is located inside the sub-atmosphere test cabin 5, the workpiece 3 to be welded is placed on the work platform 4 inside the sub-atmosphere test cabin 5, and the movement of the workpiece 3 to be welded during welding is realized by driving the motor of the work platform 4 inside the sub-atmosphere test cabin 5;

[0010] The data acquisition unit includes high resolution spectrometer 6, slit 7, variable focusing lens 8 and nanosecond enhanced CCD detector 9,

[0011] The variable focusing lens 8 is installed at the input end of the high resolution spectrometer 6, there is a slit 7 between the variable focusing lens 8 and the high resolution spectrometer 6, and the high resolution spectrometer 6 is connected with the data analysis processing unit through the nanosecond enhanced CCD detector 9.

[0012] Further, the adjustment range of the width of the slit 7 meets 0.01mm-3mm, and the slit 7 is in the same plane as the welding plasma.

[0013] Further, the detection wavelength range of the high resolution spectrometer 6 meets 200nm-1000nm, the resolution of the high resolution spectrometer 6 meets λ / Δλ>10000, and the high resolution spectrometer 6 contains diffraction gratings with different notch densities.

[0014] Further, the data analysis processing unit includes computer 10, spectral data analysis and data fitting output software;

[0015] Further, the built-in analysis software of the computer 10 obtains the fluctuation of the relative intensity of the spectral line transmitted by the data acquisition unit in real time with time, the program automatically selects the characteristic spectral line of the independent characteristic peak with signal-to-noise ratio greater than 100 as the analysis object;At any moment in the acquisition process, the electron density of the plasma is calculated by using the broadening of the selected characteristic spectral line.

[0016] Further, the broadening of the spectral line is caused by stark effect So the full width at half maximum of the spectral line is equal to the stark broadening That is:

[0017]

[0018] The electron density is calculated from the spectral data; wherein w is the electron collisional broadening coefficient, N e is the electron density, and FWHM is the full width at half maximum of the characteristic spectral line fitted by Lorentzian line shape; only the full width at half maximum of the characteristic spectral line of the excited state of the material is needed to calculate the corresponding electron density N e .

[0019] Further, a number of different electron densities and corresponding weld penetration are measured to obtain a linear mathematical model of the electron density and the penetration, and the model is input into the data fitting output software built in the computer 10 to obtain the online detection system model of the material.

[0020] A detection method of a sub-atmosphere laser welding penetration online detection system based on high-resolution spectrum, the detection method adopts the sub-atmosphere laser welding penetration online detection system based on high-resolution spectrum as described above, and the detection method comprises the following steps:

[0021] Step 1, fixing the sample to be welded 3 on the moving platform 4, and adjusting the environmental pressure of the sub-atmosphere test cabin 5 to the required value;

[0022] Step 2, turning on the high-resolution spectrometer 6, adjusting the position and focal length of the variable focusing lens 8, so that it can be accurately focused on the position of the welding plasma of the sample to be welded 3;

[0023] Step 3, setting and adjusting the related parameters and detection range of the high-resolution spectrometer 6;

[0024] Step 4, setting the welding parameters, turning on the laser 1, and focusing the laser beam on the sample to be welded 3 through the optical fiber after the laser beam is transmitted through the optical fiber and focused on the gun head 2;

[0025] Step 5, part of the plasma light signal generated in the welding process is captured by the variable focusing lens 8, transmitted to the high-resolution spectrometer 6, and decomposed into spectral lines and intensity distribution data by the high-resolution spectrometer 6, and then transmitted to the data analysis software in the computer 10 in real time;

[0026] Step 6, the software selects a characteristic spectral line with high resolution, high signal-to-noise ratio and obvious characteristics as the analysis object, obtains the full width at half maximum of the characteristic spectral line, and solves the electron density;

[0027] Step 7, taking out the welded sample, obtaining the penetration value of the weld cross section under the welding parameters, and recording the penetration value and the electron density value as (H1, N e 1);

[0028] Step 8, adjusting the welding parameters, repeating steps 1-7, and obtaining a number of electron density and corresponding weld penetration data (H2, N e2), (H3, N e 3), (H4, N e 4)…

[0029] Step 9, linearly fitting the obtained several groups of electron density and the penetration value, and storing the model in a data fitting output software, so as to realize online detection of the penetration of the thick-wall metal material under the condition of laser welding in a sub-atmospheric atmosphere.

[0030] Further, the step 3 is specifically setting basic parameters of the high-resolution spectrometer 6 for detection, selecting a suitable grating, and adjusting the detection range of the spectrometer to a suitable wavelength region.

[0031] Further, the step 6 is specifically solving the electron density, wherein the broadening of the spectrum line is caused by the stark effect , so that the full width at half maximum of the spectrum line is equal to the stark broadening , that is:

[0032]

[0033] The electron density is calculated from the spectrum data, wherein w is an electron collision broadening coefficient, N e is the electron density, and FWHM is the full width at half maximum of the characteristic spectrum line fitted by the Lorentz line type; only the full width at half maximum of the characteristic spectrum line of the material in the excited state after fitting can be calculated to obtain the corresponding electron density N e .

[0034] Further, a plurality of different electron densities and corresponding welding penetrations are measured, a linear mathematical model of the electron density and the penetration is obtained, the model is input into a data fitting output software built in the computer 10, and a model of the online detection system of the material is obtained.

[0035] A computer device comprises a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements the method as described above when executing the computer program.

[0036] The beneficial effects of the present application are:

[0037] The present application can quickly and accurately judge the penetration of the laser welding process in a sub-atmospheric environment in real time.

[0038] The present application first discovers that the electron density of the plasma in a sub-atmospheric environment is in a linear proportional relationship with the weld penetration, and the real-time welding penetration can be indirectly deduced by detecting the electron density of the plasma.

[0039] The present application realizes online monitoring of the penetration of laser welding in a sub-atmospheric environment by using a high-resolution spectrum method.

[0040] The detection precision of the application is high, and the application belongs to non-contact non-destructive online indirect measurement, and is not affected by the size of the keyhole space and plasma eruption. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a structural schematic diagram of the application.

[0042] Figure 2 is a schematic diagram of the titanium alloy plasma electron density and weld penetration when establishing a linear model process of the application, wherein (a) the titanium alloy plasma electron density is 6.73x10 17 cm 3 schematic diagram of the weld penetration, (b) the titanium alloy plasma electron density is 4.69x10 17 cm 3 schematic diagram of the weld penetration, (c) the titanium alloy plasma electron density is 2.81x10 17 cm 3 schematic diagram of the weld penetration, (d) the titanium alloy plasma electron density is 2.41x10 17 cm 3 schematic diagram of the weld penetration.

[0043] Figure 3 is a schematic diagram of the linear mathematical model of the titanium alloy online detection system electron density and penetration of the application.

[0044] Figure 4 is a schematic diagram of the deviation of the online detection numerical value and the actual numerical value of the penetration of the application, wherein (a) is the actual penetration of 16.3mm, (b) is the actual penetration of 25.5mm, and (c) is the actual penetration of 27.5mm. DETAILED DESCRIPTION

[0045] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0046] It should be understood that the term "comprising" as used in this specification and in the following claims indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0047] It should also be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and the appended claims of the present application, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0048] The technical solutions in the embodiments of the present application are described clearly and completely below. Figures 1-4 It should be apparent that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other manners different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0050] Embodiment one

[0051] It is found that the plasma electron density in the sub-atmosphere environment is closely related to the evaporation and ionization of the material, and the laser energy utilization rate of the material is in a linear negative correlation with the plasma electron density, which makes it possible to use high-resolution spectral detection to detect the plasma physical quantity and associate it with the welding penetration. Therefore, in view of the technical gap in the existing sub-atmosphere laser welding penetration detection, a kind of non-contact online detection method for penetration based on high-resolution spectral information is proposed, so as to quickly and accurately judge the penetration of the sub-atmosphere environment laser welding process in real time.

[0052] The embodiment provides a kind of sub-atmosphere laser welding penetration online detection system based on high-resolution spectrum, the system includes welding unit and data acquisition unit and data analysis processing unit, as shown in Figure 1 As shown in the figure;

[0053] The welding unit includes laser 1, focused laser gun head 2, welding workpiece 3, motion platform 4 and sub-atmosphere test cabin 5,

[0054] The laser generated by the laser 1 is emitted by the focused laser gun head 2 and acts on the workpiece 3 to be welded, the laser gun head 2 is located inside the sub-atmosphere test cabin 5, the workpiece 3 to be welded is placed on the work platform 4 inside the sub-atmosphere test cabin 5, and the movement of the workpiece 3 to be welded in the welding process is realized by driving the motor of the work platform 4 inside the sub-atmosphere test cabin 5; the sub-atmosphere test cabin 5 can provide a sub-atmosphere environment pressure less than 101kPa for the entire welding environment;

[0055] The data acquisition unit comprises a high-resolution spectrometer 6, a slit 7, a variable focusing lens 8 and a nanosecond enhanced CCD detector 9. The main function of the data acquisition unit is to acquire the spectral information of the plasma in the sub-atmospheric laser deep penetration welding process in a non-contact manner and transmit the spectral data to the subsequent data processing unit in real time.

[0056] The nanosecond enhanced CCD detector 9 meets the nanosecond level of time resolution, and the shortest acquisition interval can reach the microsecond level.

[0057] The variable focusing lens 8 is installed at the input end of the high-resolution spectrometer 6. The variable focusing lens 8 and the high-resolution spectrometer 6 are connected through the slit 7. The high-resolution spectrometer 6 is connected with the data analysis processing unit through the nanosecond enhanced CCD detector 9.

[0058] The variable focusing lens 8 accurately focuses the signal detection position of the spectrometer at the welding plasma position, effectively avoiding the interference of stray light in the welding environment on the spectral data.

[0059] The nanosecond enhanced CCD detector 9 meets the nanosecond level of time resolution, and the shortest acquisition interval can reach the microsecond level.

[0060] The data analysis processing unit comprises a computer 10, spectral data analysis and data fitting output software.

[0061] The analysis software built in the computer 10 obtains the fluctuation of the relative intensity of the spectral line with time transmitted by the data acquisition unit in real time. The program automatically selects the characteristic spectral line with a signal-to-noise ratio greater than 100 as the analysis object. At any moment during the acquisition process, the electron density of the plasma is calculated by using the broadening of the selected characteristic spectral line.

[0062] Further, the adjustment range of the width of the slit 7 meets 0.01mm-3mm. The slit 7 and the welding plasma are in the same plane. Since the slit 7 exists, only part of the light signal of the plasma can enter the resolution spectrometer 6, thereby preventing overexposure and stray light interference.

[0063] Further, the detection wavelength range of the high-resolution spectrometer 6 meets 200nm-1000nm. The resolution of the high-resolution spectrometer 6 meets λ / Δλ>10000. The high-resolution spectrometer 6 contains diffraction gratings with different marking densities.

[0064] Further, the broadening of the spectral line is caused by the stark effect Therefore, the full width at half maximum (FWHM) of the spectral line is equal to the stark broadening , that is:

[0065]

[0066] The electron density can be calculated from the spectral data; where w is the electron collisional broadening coefficient, N e is the electron density, FWHM is the full width at half maximum of the characteristic spectral line fitted by Lorentzian line shape; only the fitted full width at half maximum (FWHM) of the characteristic spectral line of the material in the excited state is needed to calculate the corresponding electron density N e .

[0067] Further, a number of different electron densities (by changing the welding parameters) and corresponding welding penetration (H) are measured, and a linear mathematical model of the electron density and the penetration is obtained, which is input into the data fitting output software built in the computer 10 to obtain the online detection system model for this material.

[0068] After the system model is established and stored in the computer, subsequent real-time online detection of the penetration of the material under any welding parameters and at any welding time can be realized.

[0069] A specific implementation case is,

[0070] As shown in Figure 1 , the welding unit includes a laser 1, a focused laser gun head 2, a welding workpiece 3, a motion platform 4, and a sub-atmosphere test cabin 5. In this implementation case, a YLS-30000 type 30kW fiber laser produced by IPG company is used, and the output wavelength is 1070nm. The laser beam is transmitted through an optical fiber with a core diameter of 300μm, collimated by a 200mm lens, and focused by a 460mm lens to obtain a beam waist diameter of 0.69mm. The laser gun head is kept stationary inside the vacuum box, and the adjustment of the welding process motion is realized by controlling the motor of the work platform in the vacuum chamber to move the test plate. The test material used is a 40mm thick annealed Ti6Al4V alloy, and the environmental pressure of the sub-atmosphere test cabin is set to 1000Pa.

[0071] The data acquisition unit includes a high-resolution spectrometer 6, a slit 7, a variable focusing lens 8, and an enhanced CCD detector 9.

[0072] In this implementation case, an ARC-SP-2750 high-resolution spectrometer produced by Princeton Instruments of the United States and a PI-MAX4:1024 enhanced CCD detector are used. Before the spectral test, the spectrometer is calibrated by a mercury lamp (Hg-lamp) standard light source. The position of the variable focusing lens is adjusted to accurately focus on the welding position, and the distance between the lens and the welding position is set to 2m.

[0073] The slit 7 has a width of 0.2 mm, the grating of the high-resolution spectrometer 6 is selected as 1200 g / mm, the detection range of the spectrometer is set to 390-402 nm, and the data integration time is set to 500 ns.

[0074] The laser power is set to 10 kW, the welding speed is set to 0.8 m / min, and other welding parameters are set. The laser is started, and the laser beam is focused through the gun head and acts on the titanium alloy test plate.

[0075] The spectrometer detects the plasma light signal in real time and transmits it to the data analysis and processing unit in real time. The data analysis and processing unit includes a computer 10, spectral data analysis and data fitting output software.

[0076] In this embodiment, the Al I 396.15 nm spectral line is selected for sub-atmospheric environment laser welding plasma electron density calculation. At this time, the full width at half maximum of the Al I 396.15 nm spectral line detected by the spectrometer is 0.0592 nm, and the built-in data analysis and processing software of the computer will solve the plasma electron density under this welding parameter according to the formula The plasma electron density under this welding parameter is calculated as 2.41×10 17 cm 3 .

[0077] Stop the laser, take out the titanium alloy welding sample, cut the cross section to obtain the penetration depth value of 28.5 mm, and record the experimental data as (28.5, 2.41×10 17 ).

[0078] Adjust the welding parameters and repeat the above process to obtain several groups of electron density and corresponding welding penetration data, recorded as (26.8, 2.81×10 17 ), (18.5, 4.69×10 17 ), (10, 6.73×10 17 ), as shown in Figure 2 .

[0079] Linear fitting is performed on the obtained several groups of electron density and penetration depth values, as shown in Figure 3 , the fitting result is H=38.81523-4.29453×10 -17 Ne, R 2 =0.99981. Store the model in the software, and thus the model of the titanium alloy sub-atmospheric environment laser welding penetration online detection system is established.

[0080] Optionally, three groups of welding parameters are used for model verification, and the experimental results are as shown in Figure 4The results of the penetration detection using the method of the application are 15.41 mm, 24.34 mm, and 27.82 mm, respectively, and the deviation values from the actual penetration results are 0.89 mm, 1.16 mm, and -0.32 mm, respectively, and the error of the detection results is 5.46%, 4.55%, and 1.16%, respectively.

[0081] The results show that the sub-atmosphere laser welding penetration online detection system and method have high detection accuracy, good operability, and reusability.

[0082] Embodiment Two

[0083] In the sub-atmosphere environment, the electron density of the laser welding plasma has a linear proportional relationship with the weld penetration. Therefore, only the linear mathematical model of the plasma electron density and the penetration of a certain material is obtained first, and based on this model, the welding penetration data at each moment can be solved by real-time detection of the plasma electron density in the actual welding process. Since the two physical quantities of electron density and penetration required by the model are in a linear proportional relationship, the amount of data required for model establishment is less, and the operability is strong. After the model is established, the data of any welding parameters of the material can be calculated using this model to obtain the penetration value, and the reusability is strong.

[0084] The embodiment provides a detection method of a sub-atmosphere laser welding penetration online detection system based on high-resolution spectroscopy. The detection method adopts the sub-atmosphere laser welding penetration online detection system based on high-resolution spectroscopy as described in Embodiment One. The detection method comprises the following steps:

[0085] Step 1, fixing the sample to be welded 3 on the moving platform 4, and adjusting the environment pressure of the sub-atmosphere test cabin 5 to the required value;

[0086] Step 2, turning on the high-resolution spectrometer 6, adjusting the position and focal length of the variable focusing lens 8, so that it can be accurately focused on the welding plasma position of the sample to be welded 3;

[0087] Step 3, setting and adjusting the related parameters and detection range of the high-resolution spectrometer 6;

[0088] Step 4, setting the welding parameters, turning on the laser 1, and transmitting the laser beam through the optical fiber and focusing on the gun head 2 to act on the sample to be welded 3;

[0089] Step 5, part of the plasma light signal generated in the welding process is captured by the variable focusing lens 8, transmitted to the high-resolution spectrometer 6, and decomposed into spectral lines and intensity distribution data by the high-resolution spectrometer 6, and then transmitted to the data analysis software in the computer 10 in real time;

[0090] Step 6, the software selects a characteristic spectrum line with high resolution, high signal-to-noise ratio and obvious characteristics as an analysis object, obtains the full width at half maximum of the characteristic spectrum line, and solves the electron density according to a related formula built in the software;

[0091] Step 7, the welded sample is taken out, the weld cross-section penetration value of the welding parameter is obtained, and the penetration value and the electron density value are recorded as (H1, Ne1);

[0092] Step 8, the welding parameters are adjusted, and steps 1-7 are repeated to obtain a plurality of groups of electron density and corresponding welding penetration data, recorded as (H2, N e 2), (H3, N e 3), (H4, N e 4)……

[0093] Step 9, the obtained plurality of groups of electron density and penetration value are linearly fitted, and the model is stored in the data fitting output software, so as to realize online detection of the laser welding penetration of the thick wall metal material under the sub-atmospheric atmosphere condition;

[0094] At this point, the model of the online penetration detection system for the material is established, and the model can be directly called in the subsequent to display the welding penetration in real time by detecting the electron density of the material laser welded in the sub-atmospheric atmosphere environment.

[0095] Further, the step 3 specifically sets basic parameters of the high-resolution spectrometer 6 for detection, selects a suitable grating, and adjusts the detection range of the spectrometer to a suitable wavelength region.

[0096] Further, the computer 10 built-in analysis software obtains the fluctuation of the relative intensity of the spectrum line transmitted in real time by the data acquisition unit with time, and the program automatically selects a characteristic spectrum line with a signal-to-noise ratio greater than 100 as an analysis object; at any time during the acquisition process, the electron density of the plasma is calculated by using the broadening of the selected characteristic spectrum line.

[0097] Further, the electron density solved in the step 6 is specifically that the broadening of the spectrum line is caused by the stark effect , so the full width at half maximum (FWHM) of the spectrum line is equal to the stark broadening , that is:

[0098]

[0099] The electron density can be calculated from the spectrum data; wherein w is an electron collision broadening coefficient, N e is the electron density, and FWHM is the full width at half maximum of the characteristic spectrum line fitted by the Lorentz line type; only the fitted full width at half maximum (FWHM) of the characteristic spectrum line of the material in the excited state is obtained, and the corresponding electron density Ne .

[0100] Further, a linear mathematical model of electron density and penetration depth is obtained by measuring several groups of different electron densities (by changing welding parameters) and corresponding welding penetration depths (H), and the model is input into data fitting output software built in the computer (10) to obtain the model of the online detection system for the material.

[0101] After the system model is completed, it is stored in the computer, and subsequent real-time online detection of the penetration depth of the material under any welding parameters and at any welding time can be realized.

[0102] Embodiment three

[0103] The electronic device provided by the embodiment of the present application includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected through a bus. Specifically, the processor realizes any step in the above embodiment one by running the above computer program stored in the memory.

[0104] It should be understood that, in the embodiment of the present application, the processor can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0105] The memory can include read-only memory, flash memory, and random access memory, and provide instructions and data to the processor. Part or all of the memory can also include non-volatile random access memory.

[0106] As can be seen from the above, the electronic device provided by the embodiment of the present application can realize the detection method of the online detection system of the sub-atmosphere laser welding penetration depth based on high-resolution spectrum as described in the embodiment two by running the computer program, and for the first time proposes to realize online detection of the penetration depth by using a high-resolution spectrum method for the laser welding process in a sub-atmosphere environment.

[0107] It should be understood that the above-mentioned integrated modules / units, if implemented in the form of software function units and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiments of the method can also be completed by a computer program instructing related hardware, and the above-mentioned computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of the above-mentioned various method embodiments can be implemented. The above-mentioned computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The above-mentioned computer readable medium can include any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the above-mentioned computer readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0108] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0109] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of functional units and modules is taken as an example, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the above-mentioned device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be realized in the form of hardware or software function unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the application. The specific working process of the unit and module in the above-mentioned system can refer to the corresponding process in the above-mentioned method embodiments, which will not be repeated here.

[0110] It should be noted that the method provided by the above embodiments and details thereof can be combined with the apparatus and device provided by the embodiments, and mutual reference is not repeated.

[0111] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0112] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / terminal device and method can be implemented in other ways. For example, the above-described apparatus / device embodiments are merely illustrative, and the division of the above-described modules or units is merely a logical function division, and an actual implementation can be divided into another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0113] The above embodiments are merely used to illustrate the technical solutions of the present application, rather than limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An online detection system for penetration depth in sub-atmosphere laser welding based on high-resolution spectroscopy, characterized in that, The system includes a welding unit, a data acquisition unit, and a data analysis and processing unit. The welding unit includes a laser (1), a focused laser gun head (2), a welding workpiece (3), a motion platform (4), and a sub-atmosphere test chamber (5). The laser generated by the laser (1) is emitted by the focused laser gun head (2) and acts on the welding workpiece (3). The laser gun head (2) is located inside the sub-atmosphere test chamber (5). The welding workpiece (3) is placed on the working platform (4) inside the sub-atmosphere test chamber (5). The movement of the welding workpiece (3) during the welding process is adjusted by driving the motor of the working platform (4) inside the sub-atmosphere test chamber (5). The data acquisition unit includes a high-resolution spectrometer (6), a slit (7), a variable focusing lens (8), and a nanosecond-level enhanced CCD detector (9). The variable focusing lens (8) is installed at the input end of the high-resolution spectrometer (6), and there is a slit (7) between the variable focusing lens (8) and the high-resolution spectrometer (6). The high-resolution spectrometer (6) is connected to the data analysis and processing unit through a nanosecond-level enhanced CCD detector (9).

2. The system according to claim 1, characterized in that, The width of the slit (7) can be adjusted within the range of 0.01mm-3mm, and the slit (7) is on the same plane as the welding plasma.

3. The system according to claim 1, characterized in that, The high-resolution spectrometer (6) has a detection wavelength range of 200nm to 1000nm, a resolution of λ / Δλ > 10000, and contains diffraction gratings with different scribe densities.

4. The system according to claim 1, characterized in that, The data analysis and processing unit includes a computer (10) and spectral data analysis and data fitting output software; The computer (10) has built-in analysis software that obtains the relative intensity fluctuation of the spectral lines transmitted in real time from the data acquisition unit. The program automatically selects the characteristic spectral lines of independent characteristic peaks with a signal-to-noise ratio greater than 100 as the analysis object. At any time during the acquisition process, the plasma electron density is calculated by using the broadening of the selected characteristic spectral lines.

5. The system according to claim 4, characterized in that, Spectral line broadening is due to the Stark effect This causes the full width at half maximum (FWHM) of the spectral lines to be affected by the Stark broadening. Equal, that is: The electron density is calculated from the spectral data; among which, The electron collision broadening factor. The electron density is given by FWHM, which is the full width at half maximum (FWHM) of the characteristic spectral lines fitted with the Lorentz line shape. The electron density can be calculated simply by obtaining the fitted FWHM of the characteristic spectral lines of the excited state of the material. ; Several sets of different electron densities and corresponding welding penetrations were measured to obtain a linear mathematical model of electron density and penetration. This model was then input into the data fitting output software built into the computer (10) to obtain the online detection system model of this material.

6. A detection method for an online sub-atmosphere laser welding penetration depth detection system based on high-resolution spectroscopy, characterized in that, The detection method employs the online sub-atmosphere laser welding penetration detection system based on high-resolution spectroscopy as described in any one of claims 1-5, and the detection method includes the following steps: Step 1: Fix the welding workpiece (3) on the motion platform (4) and adjust the environmental pressure of the sub-atmosphere test chamber (5) to the required value; Step 2: Turn on the high-resolution spectrometer (6), and adjust the position and focal length of the variable focusing lens (8) so that it can be accurately focused on the welding plasma position of the welding workpiece (3); Step 3: Set and adjust the relevant parameters and detection range of the high-resolution spectrometer (6); Step 4: Set welding parameters, turn on the laser (1), and the laser beam is transmitted through the optical fiber and focused on the welding workpiece (3) by the gun head (2); Step 5: A portion of the plasma light signal generated during the welding process is captured by the variable focusing lens (8) and transmitted to the high-resolution spectrometer (6). The high-resolution spectrometer (6) decomposes it into light spectral lines and intensity distribution data, and transmits them in real time to the data analysis software inside the computer (10). Step 6: The software selects characteristic spectral lines with high resolution, high signal-to-noise ratio, and obvious features as the analysis object, obtains the full width at half maximum (FWHM) of the characteristic spectral lines, and solves for the electron density. Step 7: Remove the welded sample and obtain the weld penetration value of the weld cross-section. Record this penetration value and the electron density value as ( H 1 ，N e 1); Step 8: Adjust welding parameters, repeat steps 1 to 7, and obtain several sets of electron density and corresponding weld penetration data, which are recorded as ( H 2, N e 2), ( H 3, N e 3), ( H 4, N e 4) ... Step 9: Linearly fit the obtained sets of electron densities and penetration depth values, and store them in the data fitting output software to realize online detection of penetration depth in sub-atmosphere laser welding based on high-resolution spectroscopy.

7. The method according to claim 6, characterized in that, Step 3 specifically involves setting the basic parameters for detection by the high-resolution spectrometer (6), selecting a suitable grating, and adjusting the detection range of the spectrometer to a suitable wavelength region.

8. The method according to claim 6, characterized in that, The computer (10) has built-in analysis software that obtains the relative intensity fluctuation of the spectral lines transmitted in real time from the data acquisition unit. The program automatically selects the characteristic spectral lines of independent characteristic peaks with a signal-to-noise ratio greater than 100 as the analysis object. At any time during the acquisition process, the plasma electron density is calculated by using the broadening of the selected characteristic spectral lines.

9. The method according to claim 8, characterized in that, In step 6, the electron density is specifically calculated, and the broadening of the spectral lines is due to the Stark effect. This causes the full width at half maximum (FWHM) of the spectral lines to be affected by the Stark broadening. Equal, that is: The electron density is calculated from the spectral data; among which, The electron collision broadening factor. The electron density is given by FWHM, which is the full width at half maximum (FWHM) of the characteristic spectral lines fitted with the Lorentz line shape. The electron density can be calculated simply by obtaining the fitted FWHM of the characteristic spectral lines of the excited state of the material. ; Several sets of different electron densities and corresponding welding penetrations were measured to obtain a linear mathematical model of electron density and penetration. This model was then input into the data fitting output software built into the computer (10) to obtain the online detection system model of this material.

10. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the method as described in any one of claims 7-9.

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