Welding pool morphology detection device, welding device and method

Abstract

The present invention relates to a welding molten pool morphology detection device and a welding device and method. The detection method includes the following steps: placing a base material on an insulating wedge, using a pulsed laser to irradiate a specific area on the lower surface of the insulating wedge to form a row of light spots, the light spot position generates an ultrasonic signal and is transmitted through the insulating wedge to the base material molten pool to generate a reflection signal; synchronously collecting the reflection signal of each ultrasonic signal in the specific area on the lower surface of the insulating wedge; obtaining the ultrasonic velocity of the reflected signal in the relevant medium in the propagation path and the arrival time of the reflection signal peak, and calculating the internal contour cross-sectional curve of the molten pool, the upper surface cross-sectional curve of the molten pool, the keyhole contour cross-sectional curve, the bubble lower surface cross-sectional curve, and the bubble upper surface cross-sectional curve; repeating the above detection steps until the entire molten pool is covered, and obtaining the three-dimensional morphology of the internal contour of the molten pool, the three-dimensional morphology of the upper surface of the molten pool, the three-dimensional morphology of the keyhole contour, and the three-dimensional morphology of the bubble, which is conducive to adjusting the welding process parameters and improving the welding quality.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to a welding pool morphology detection device, a welding device and a welding method. Background Art

[0002] The morphology of the welding pool is a factor closely related to the welding process and welding quality. The morphology of the molten pool not only determines the shape of the weld, but also has a close relationship with the crystallization process of the weld. It has an important influence on the microstructure and mechanical properties of the weld and the welding quality. For example, the most important penetration depth in the internal contour of the molten pool directly affects the bearing capacity of the joint. The depth-to-width ratio of the molten pool directly affects the welding quality of the joint. The air gap caused by the failure to eliminate bubbles in the molten pool reduces the strength of the joint.

[0003] Reliably detecting and extracting weld pool morphology information is crucial for understanding fundamental welding theories, such as the coupling between the welding heat source and the weld pool and the weld penetration state. However, in actual welding, the oscillation amplitude of the weld pool surface is very weak, and the internal morphology of the weld pool cannot be directly observed. Accurately acquiring information about the surface and internal morphology of the weld pool is extremely difficult. Furthermore, traditional weld pool topography measurement methods (arc voltage, arc light, and structured light) are unable to characterize the internal morphology of the weld pool.

[0004] In summary, how to solve the problem of detecting the surface and internal morphology of the high-temperature liquid molten pool during the welding process has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] In response to the problems existing in the prior art, one of the purposes of the present invention is to provide a welding pool morphology detection method that can realize online detection of the surface and internal morphology information of the welding high-temperature liquid molten pool, thereby facilitating the adjustment of welding process parameters and improving welding quality.

[0006] A second object of the present invention is to provide a device for detecting the morphology of a welding pool.

[0007] The third object of the present invention is to provide a welding device that can realize online detection of molten pool morphology and improve welding quality.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for detecting the morphology of a welding pool comprises the following steps:

[0010] The base metal is placed on an insulating wedge, and a pulsed laser is used to irradiate a specific area on the lower surface of the insulating wedge to form a row of light spots. Each light spot generates an ultrasonic signal and is transmitted through the insulating wedge to the base metal molten pool to generate a reflection signal.

[0011] The data acquisition card synchronously collects the reflected signal of each ultrasonic signal in a specific area on the lower surface of the thermal insulation wedge;

[0012] Obtain the ultrasonic velocity of the reflected signal in the relevant medium in the propagation path and the arrival time of the reflected signal peak, calculate the position of the relevant characteristic points in the molten pool relative to the lower surface of the base material, and then obtain the internal contour cross-sectional curve of the molten pool, the cross-sectional curve of the upper surface of the molten pool, the contour cross-sectional curve of the keyhole, the cross-sectional curve of the lower surface of the bubble, and the cross-sectional curve of the upper surface of the bubble;

[0013] Scan the next column along the welding direction and repeat the above detection steps until the entire molten pool is covered. Multiple related cross-sectional curves are obtained in turn and smoothed to obtain the three-dimensional morphology of the internal contour of the molten pool, the three-dimensional morphology of the upper surface of the molten pool, the three-dimensional morphology of the keyhole contour, the lower surface curved surface of the bubble, and the upper surface curved surface of the bubble; the lower surface curved surface of the bubble and the upper surface curved surface of the bubble are smoothly connected to obtain the three-dimensional morphology of the bubble, completing the detection of the welding molten pool morphology.

[0014] Furthermore, the reflection signal of the ultrasonic signal in the specific area of ​​the lower surface of the insulating wedge is collected in the following way: the laser interferometer generates a detection laser to irradiate the specific area of ​​the lower surface of the insulating wedge below the molten pool to detect the reflection signal, and sends the detection result to the data acquisition card.

[0015] Furthermore, the detection laser is vertically irradiated on a specific area on the lower surface of the thermal insulation wedge.

[0016] Furthermore, a specific area on the lower surface of the insulating wedge is located directly below the molten pool and includes the entire molten pool area.

[0017] Furthermore, the detection of the welding pool morphology is achieved by obtaining the ultrasonic velocity in the molten pool, the ultrasonic velocity in the base material, the ultrasonic velocity in the bubble, the peak arrival time of the reflection signal of the lower surface of the base material and the relevant characteristic points in the molten pool, and establishing a system of equations consisting of the following multiple equations to solve and obtain the position of the relevant characteristic points in the molten pool relative to the lower surface of the base material, where:

[0018] When the propagation path is free of bubbles and keyholes:

[0019] The distance between the lower surface of the base material and the contour point of the molten pool = the ultrasonic velocity in the base material x (the peak arrival time of the reflected signal at the contour point of the molten pool - the peak arrival time of the reflected signal at the lower surface of the base material) / 2;

[0020] The distance between the upper surface point of the molten pool and the contour point of the molten pool = the ultrasonic velocity in the molten pool x (the peak arrival time of the reflection signal at the upper surface point of the molten pool - the peak arrival time of the reflection signal at the contour point of the molten pool) / 2;

[0021] The distance between the lower surface of the base metal and the upper surface of the molten pool = the distance between the lower surface of the base metal and the contour point of the molten pool + the distance between the upper surface point of the molten pool and the contour point of the molten pool;

[0022] When the propagation path has a keyhole:

[0023] The distance between the lower surface of the base material and the contour point of the molten pool = the ultrasonic velocity in the base material x (the peak arrival time of the reflected signal at the contour point of the molten pool - the peak arrival time of the reflected signal at the lower surface of the base material) / 2;

[0024] The distance between the keyhole contour point and the molten pool contour point = ultrasonic velocity in the molten pool x (peak arrival time of the reflection signal at the keyhole contour point - peak arrival time of the reflection signal at the molten pool contour point) / 2;

[0025] The distance between the lower surface of the base metal and the keyhole contour point = the distance between the lower surface of the base metal and the molten pool contour point + the distance between the molten pool contour point and the keyhole contour point;

[0026] When there are bubbles in the propagation path:

[0027] The distance between the lower surface of the base material and the contour point of the molten pool = the ultrasonic velocity in the base material x (the peak arrival time of the reflected signal at the contour point of the molten pool - the peak arrival time of the reflected signal at the lower surface of the base material) / 2;

[0028] The distance between the molten pool contour point and the bubble lower surface point = ultrasonic velocity in the molten pool x (the arrival time of the peak value of the reflection signal at the bubble lower surface point - the arrival time of the peak value of the reflection signal at the molten pool contour point) / 2;

[0029] The distance between the upper surface point of the bubble and the lower surface point of the bubble = ultrasonic velocity in the bubble x (the peak arrival time of the reflection signal at the upper surface point of the bubble - the peak arrival time of the reflection signal at the lower surface point of the bubble) / 2;

[0030] The distance between the upper surface point of the molten pool and the upper surface point of the bubble = ultrasonic velocity in the molten pool x (peak arrival time of the reflection signal at the upper surface point of the molten pool - peak arrival time of the reflection signal at the upper surface point of the bubble) / 2;

[0031] The distance between the lower surface of the base material and the lower surface of the bubble = the distance between the lower surface of the base material and the contour point of the molten pool + the distance between the contour point of the molten pool and the lower surface point of the bubble;

[0032] The distance between the lower surface of the base material and the upper surface of the bubble = the distance between the lower surface of the base material and the lower surface of the bubble + the distance between the upper surface of the bubble and the lower surface of the bubble;

[0033] The distance between the lower surface of the base material and the upper surface point of the molten pool = the distance between the lower surface of the base material and the upper surface point of the bubble + the distance between the upper surface point of the bubble and the upper surface point of the molten pool.

[0034] Furthermore, the ultrasonic velocity in the relevant medium is obtained by combining the actual measurement results of the infrared temperature measurement system and the welding parameter library established by the temperature simulation system of the base material and the molten pool in the expert system, and establishing the stepped sound velocity in the molten pool, base material and bubble according to the material temperature gradient. According to the propagation path, the formula The average sound velocity in the medium corresponding to the propagation path is calculated, which is the ultrasonic velocity in the medium related to the propagation path.

[0035] Furthermore, when scanning the spot, all spot columns are evenly distributed, all rows are evenly distributed, and both the column distance and row distance are larger than the laser spot diameter. The column distance, row distance, and spot size are adjusted to adjust the lateral resolution of detecting the molten pool morphology.

[0036] A welding pool morphology detection device includes a heat-insulating wedge for placing a base material, a pulsed laser, a data acquisition card, and a control unit;

[0037] The pulsed laser is used to irradiate specific areas on the lower surface of the insulation wedge to form multiple rows of light spots in sequence. The light spot position generates an ultrasonic signal and transmits it through the insulation wedge to the base material molten pool to form a reflection signal;

[0038] The data acquisition card is used to synchronously collect the reflected signal of each ultrasonic signal in a specific area on the lower surface of the thermal insulation wedge and send it to the control unit;

[0039] The control unit is used to obtain the ultrasonic velocity of the reflected signal in the relevant medium in the propagation path and the arrival time of the peak of the reflected signal, and calculate the three-dimensional morphology of the internal contour of the molten pool, the three-dimensional morphology of the upper surface of the molten pool, the three-dimensional morphology of the keyhole contour and the three-dimensional morphology of the bubble.

[0040] Furthermore, it also includes a first optical path system, a second optical path system, a laser interferometer, a high-temperature resistant ultrasonic coupling agent and an infrared temperature measurement system. The upper surface of the insulating wedge is tightly connected to the base material through the high-temperature resistant ultrasonic coupling agent. The pulsed laser is used to shape the excitation laser through the first optical path system to irradiate a specific area on the lower surface of the insulating wedge to generate an ultrasonic signal. The ultrasonic signal is transmitted through the insulating wedge through the high-temperature resistant ultrasonic coupling agent to the base material molten pool to form a reflected signal. The laser interferometer is used to generate a detection laser and detect the reflected signal at the corresponding position on the lower surface of the insulating wedge through the second optical path system. The infrared temperature measurement system is used to measure the surface temperature of the molten pool and send it to the control unit to establish a stepped sound velocity in the molten pool, base material and bubbles.

[0041] A welding device includes a welding pool morphology detection device.

[0042] In general, the present invention has the following advantages:

[0043] The molten pool internal contour detection technology proposed in the present invention can realize the online measurement of the three-dimensional morphology of the internal contour of the high-temperature liquid molten pool, the upper surface of the molten pool, the keyhole contour and the bubble during welding; the proposed temperature step compensation ultrasonic velocity method can improve the detection accuracy of the molten pool morphology; by reducing the scanning laser spot size and the spot distance, the lateral resolution of the internal contour of the molten pool can be improved; adjusting the welding process parameters according to the detection results can improve the welding quality and enhance the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the main structure of the present invention;

[0045] Figure 2 Schematic diagram of the molten pool morphology detection solution of the present invention;

[0046] Figure 3 Schematic diagram of the molten pool morphology detection solution of the present invention;

[0047] Figure 4 It is a flow chart of the molten pool morphology detection scheme of the present invention.

[0048] In the picture:

[0049] 11- host computer, 12- synchronization controller;

[0050] 21- welding system, 22- three-dimensional motion platform;

[0051] 31- pulse laser, 32- first optical path system, 33- laser interferometer, 34- second optical path system, 35- data acquisition card, 36- infrared temperature measurement system;

[0052] 41-insulation wedge;

[0053] 51-base material, 52-weld, 53-light spot, 54-bubble;

[0054] 61-molten pool, 62-keyhole. DETAILED DESCRIPTION

[0055] The present invention will be described in further detail below.

[0056] like Figure 1 As shown, a welding device includes a control unit, a welding unit and a molten pool morphology detection device.

[0057] The control unit is connected to the welding unit and the molten pool morphology detection device through signal lines, and includes a host computer 11, a motion control module and a synchronization controller 12. The host computer 11 performs motion control and parameter modulation on the welding unit and the molten pool morphology detection device, and performs signal analysis and processing. The motion control module controls the three-dimensional motion platform 22 to move three-dimensionally according to the set program, and at the same time controls the pulse laser 31 to perform pulse laser two-dimensional motion scanning according to the set program. The synchronization controller 12 provides a unique timing for triggering and ending the welding unit and the molten pool morphology detection device to ensure synchronization of excitation and detection of ultrasonic signals.

[0058] Specifically, the welding unit includes a welding system 21 and a three-dimensional motion platform 22. The welding system 21 outputs the required welding heat source according to the welding parameter control program of the host computer 11. The three-dimensional motion platform 22 is fixedly connected to the insulating wedge 41. The upper surface of the insulating wedge 41 is tightly connected to the base material 51 through a high-temperature resistant ultrasonic coupling agent. The upper and lower surfaces of the insulating wedge 41 are smooth and neat. The three-dimensional motion platform 22 drives the base material 51 for mobile welding according to the control program of the host computer 11.

[0059] Specifically, the detection unit includes a pulse laser 31, a first optical path system 32, a second optical path system 34, a laser interferometer 33, a data acquisition card 35 and an infrared temperature measurement system 36. The pulse laser 31 generates an excitation laser of a specific frequency and power according to the control program of the host computer 11, and shapes the excitation laser to irradiate a specific area on the lower surface of the insulation wedge 41 through the first optical path system 32. The laser interferometer 33 generates a detection laser and detects an ultrasonic signal at a corresponding position on the lower surface of the insulation wedge 41 through the second optical path system 34. The data acquisition card 35 collects the ultrasonic signal detected by the laser interferometer 33 according to the trigger signal of the synchronization controller 12, and transmits it to the host computer 11 for data analysis. The infrared temperature measurement system 36 can measure the surface temperature of the molten pool 61 non-contact.

[0060] Specifically, the excitation laser irradiates a specific area on the lower surface of the insulation wedge 41 directly below the molten pool 61 and includes the entire molten pool 61 area, and the detection laser irradiates the lower surface of the insulation wedge 41 vertically through the second optical path system 34.

[0061] like Figure 4 As shown, a welding method comprises the following steps:

[0062] S1: Device initialization (the host computer 11 controls and adjusts the motion platform to ensure that the focus of the excitation laser and the detection laser is located on the lower surface of the thermal insulation wedge 41), program initialization (the host computer 11 sets relevant welding parameters);

[0063] S2: Welding begins, with the weld 52 located in the middle of the molten pool 61;

[0064] S3: Molten pool 61 morphology detection, including the following steps:

[0065] S3.1: The host computer 11 controls the pulse laser 31 and the data acquisition card 35 at a certain frequency through the synchronous controller 12. The pulse laser 31 generates an excitation laser with specific parameters. The first optical path system 32 Figure 2 The scanning scheme shown first irradiates the lower surface of the insulating wedge 41 along the welding direction to form a light spot S(1,1) and generate an ultrasonic signal. The ultrasonic signal is transmitted through the insulating wedge 41 and the high-temperature resistant ultrasonic coupling agent to the molten pool 61 of the base material 51. At the solid-liquid interface and the gas-liquid interface of the molten pool 61, a reflection signal is generated. The data acquisition card 35 collects the corresponding ultrasonic signal U(1,1) detected by the laser interferometer 33, and the host computer 11 records the arrival time t and amplitude a of the peak value of the relevant ultrasonic reflection signal.

[0066] S3.2: Analyze the number, amplitude, and arrival time of the reflected signal peaks in the ultrasonic signal U(1,1) recorded by the laser interferometer 33 within the set time, determine the specific propagation path of the ultrasonic signal U(1,1), and calculate the position of the relevant characteristic points in the molten pool 61 relative to the lower surface of the base material 51 through the ultrasonic velocity v in the relevant medium and the arrival time t of the ultrasonic reflected signal peak, as shown in Figure 3 As shown:

[0067] S3.2.1: For the path A1-B1-C1-D1 without bubbles 54 and keyhole 62, record the peak arrival time t of the ultrasonic reflection signal at positions B1, C1, and D1. B1 , t C1 and t D1 , through the formula The position of the contour point C1 of the molten pool 61 and the position of the upper surface point D1 of the molten pool 61 can be obtained;

[0068] S3.2.2: For a keyhole 62 path A2-B2-C2-E2, record the peak arrival time t of the ultrasonic reflection signal at positions B2, C2, and E2. B2 , t C2 and t E2 , through the formula The position of the contour point C2 of the molten pool 61 and the position of the contour point E2 of the keyhole 62 can be obtained;

[0069] S3.2.3: For the bubble 54 path A3-B3-C3-F3-G3-D3, record the peak arrival time t of the ultrasonic reflection signal at positions B3, C3, F3, G3, and D3. B3 , t C3 , t F3 , t G3 and t D3 , through the formula The position of the contour point C3 of the molten pool 61, the position of the lower surface point F3 of the bubble 54, the position of the upper surface point G3 of the bubble 54 and the position of the upper surface point D3 of the molten pool 61 can be obtained;

[0070] S3.3: Optical path system 1 Figure 2 The scanning scheme is used to scan the remaining light spots S(2,1), ..., S(n,1) in the first column in turn, and the related molten pool 61 contour points C11, C21, ..., Cn1, the upper surface points D11, D21, ..., Dn1 of the light spots S(1,1), S(2,1), ..., S(n,1) in the first column corresponding to the ultrasonic signals U(1,1), U(2,1), ..., U(n,1) are recorded, as well as the contour points E11, E21, ..., En1 of the keyhole 62, the lower surface points F11, F21, ..., Fn1 of the bubble 54, and the upper surface points G11, G21, ..., Gn1 of the bubble 54;

[0071] S3.4: Smoothing the curve obtained by connecting the contour points C11, C21, ..., Cn1 of the molten pool 61 to obtain the internal contour cross-sectional curve of the molten pool 61 in the first column; smoothing the curve obtained by connecting the upper surface points D11, D21, ..., Dn1 of the molten pool 61 to obtain the upper surface cross-sectional curve of the molten pool 61 in the first column; smoothing the curve obtained by connecting the contour points E11, E21, ..., En1 of the keyhole 62 to obtain the contour cross-sectional curve of the keyhole 62 in the first column; smoothing the curve obtained by connecting the lower surface points F11, F21, ..., Fn1 of the bubble 54 to obtain the lower surface cross-sectional curve of the bubble 54 in the first column; smoothing the curve obtained by connecting the upper surface points G11, G21, ..., Gn1 of the bubble 54 to obtain the upper surface cross-sectional curve of the bubble 54 in the first column;

[0072] S3.5: Scan the 2nd, 3rd, ..., nth columns, repeat steps S3.1-S3.4, smooth the internal contour cross-sectional curves of the molten pool 61 that connect the 1st, 2nd, ..., nth columns to obtain the 3D morphology of the internal contour of the molten pool 61, smooth the upper surface cross-sectional curves of the molten pool 61 that connect the 1st, 2nd, ..., nth columns to obtain the 3D morphology of the upper surface of the molten pool 61, smooth the contour cross-sectional curves of the keyhole 62 that connect the 1st, 2nd, ..., nth columns to obtain the 3D morphology of the keyhole 62 contour, smooth the lower surface cross-sectional curves of the bubble 54 that connect the 1st, 2nd, ..., nth columns to obtain the lower surface curved surface of the bubble 54, smooth the upper surface cross-sectional curves of the bubble 54 that connect the 1st, 2nd, ..., nth columns to obtain the upper surface curved surface of the bubble 54, and smooth the lower surface curved surface of the bubble 54 and the upper surface curved surface of the bubble 54 to obtain the 3D morphology of the bubble 54;

[0073] S4: Then, information such as the penetration depth and width of the molten pool 61 is obtained, and welding process parameters are adjusted according to the expert system to improve welding quality and achieve zero-defect welding;

[0074] S5: End detection and welding.

[0075] Specifically, such as Figure 2 As shown, in the scanning scheme of the optical path system 1 in step S3.1, all columns are evenly distributed, all rows are evenly distributed, the column distance a and the row distance b are both larger than the diameter of the laser spot 53, and the column distance a, the row distance b and the size of the spot 53 are adjusted to adjust the lateral resolution of the detection of the morphology of the molten pool 61.

[0076] Specifically, the ultrasonic velocity v in the relevant medium of step S3.2 is combined with the actual measurement results of the infrared temperature measurement system 36 and the welding parameter library established by the temperature simulation system of the base material 51 and the molten pool 61 in the expert system, and the stepped sound velocity v in the molten pool 61, the base material 51 and the bubble 54 is established according to the material temperature gradient. According to the propagation path, the formula The average sound velocity in the medium corresponding to the propagation path is calculated to be the ultrasonic velocity v in the medium related to the propagation path.

[0077] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for detecting welding pool morphology, characterized in that: The following steps are included: The base metal is placed on an insulating wedge. A pulsed laser is used to irradiate a specific area on the lower surface of the insulating wedge to form a series of light spots. Each light spot generates an ultrasonic signal, which is transmitted through the insulating wedge to the base metal molten pool to generate a reflected signal. The specific area on the lower surface of the insulating wedge is located directly below the molten pool and includes the entire molten pool area. The data acquisition card synchronously collects the reflected signal of each ultrasonic signal in a specific area on the lower surface of the thermal insulation wedge; Then, the internal profile cross-sectional curve of the molten pool, the upper surface cross-sectional curve of the molten pool, the keyhole profile cross-sectional curve, the lower surface cross-sectional curve of the bubble, and the upper surface cross-sectional curve of the bubble are obtained; Scan the next column along the welding direction and repeat the above detection steps until the entire molten pool is covered. Multiple related cross-sectional curves are obtained and smoothed in sequence to obtain the 3D morphology of the molten pool internal contour, the 3D morphology of the molten pool upper surface, the 3D morphology of the keyhole contour, the lower surface curved surface of the bubble, and the upper surface curved surface of the bubble. The lower surface curved surface and the upper surface curved surface of the bubble are smoothly connected to obtain the 3D morphology of the bubble, completing the detection of the welding pool morphology. Among them, obtaining the ultrasonic velocity of the reflected signal in the relevant medium in the propagation path includes: combining the actual measurement results of the infrared temperature measurement system and the welding parameter library established by the temperature simulation system of the base material and the molten pool in the expert system, and establishing the stepped sound velocity in the molten pool, base material and bubble according to the material temperature ladder. , according to the propagation path, through the formula , calculate the ultrasonic velocity in the bubble , ultrasonic velocity in the base material , ultrasonic velocity in the molten pool ; Among them, obtaining the position of the relevant feature points in the molten pool includes: when there are bubbles in the propagation path, The distance between the lower surface of the base material and the contour point of the molten pool = x (peak arrival time of the reflection signal at the molten pool contour point - peak arrival time of the reflection signal at the bottom surface of the parent material) / 2; The distance between the molten pool contour point and the bubble bottom surface point = x (the arrival time of the peak value of the reflection signal at the point below the bubble surface - the arrival time of the peak value of the reflection signal at the point of the molten pool contour) / 2; The distance between the upper surface point of the bubble and the lower surface point of the bubble = x (the peak arrival time of the reflection signal at the upper surface of the bubble - the peak arrival time of the reflection signal at the lower surface of the bubble) / 2; The distance between the upper surface point of the molten pool and the upper surface point of the bubble = x (arrival time of peak value of reflection signal at upper surface point of molten pool - arrival time of peak value of reflection signal at upper surface point of bubble) / 2; The distance between the lower surface of the base material and the lower surface of the bubble = the distance between the lower surface of the base material and the contour point of the molten pool + the distance between the contour point of the molten pool and the lower surface point of the bubble; The distance between the lower surface of the base material and the upper surface of the bubble = the distance between the lower surface of the base material and the lower surface of the bubble + the distance between the upper surface of the bubble and the lower surface of the bubble; The distance between the lower surface of the base material and the upper surface of the molten pool = the distance between the lower surface of the base material and the upper surface of the bubble + the distance between the upper surface of the bubble and the upper surface of the molten pool.

2. A welding pool morphology detection method according to claim 1, characterized in that: The reflected signal of the ultrasonic signal in the specific area on the lower surface of the insulating wedge is collected in the following way: the laser interferometer generates a detection laser to irradiate the specific area on the lower surface of the insulating wedge below the molten pool to detect the reflected signal, and sends the detection result to the data acquisition card.

3. A welding pool morphology detection method according to claim 2, characterized in that: The detection laser is irradiated vertically on a specific area on the lower surface of the thermal insulation wedge.

4. The method for detecting welding pool morphology according to claim 1, wherein: The specific area on the lower surface of the insulating wedge is located directly below the molten pool and includes the entire molten pool area.

5. The method for detecting welding pool morphology according to claim 1, wherein: Obtaining the position of relevant feature points in the molten pool relative to the lower surface of the base material also includes, when there are no bubbles and keyholes in the propagation path: The distance between the lower surface of the base material and the contour point of the molten pool = x (peak arrival time of the reflection signal at the molten pool contour point - peak arrival time of the reflection signal at the bottom surface of the parent material) / 2; The distance between the upper surface point of the molten pool and the molten pool contour point = x (arrival time of peak value of reflection signal at point on the upper surface of the molten pool - arrival time of peak value of reflection signal at point on the contour of the molten pool) / 2; The distance between the lower surface of the base material and the upper surface of the molten pool = the distance between the lower surface of the base material and the contour point of the molten pool + the distance between the upper surface point of the molten pool and the contour point of the molten pool; When the propagation path has a keyhole: The distance between the lower surface of the base material and the contour point of the molten pool = x (peak arrival time of the reflection signal at the molten pool contour point - peak arrival time of the reflection signal at the bottom surface of the parent material) / 2; The distance between the keyhole contour point and the molten pool contour point = x (the arrival time of the peak value of the reflection signal at the keyhole contour point - the arrival time of the peak value of the reflection signal at the molten pool contour point) / 2; The distance between the lower surface of the base material and the keyhole contour point = the distance between the lower surface of the base material and the molten pool contour point + the distance between the molten pool contour point and the keyhole contour point.

6. A welding pool morphology detection method according to claim 1, characterized in that: When scanning the spot, all spot columns are evenly distributed, all rows are evenly distributed, and the column distance and row distance are both larger than the laser spot diameter. The column distance, row distance and spot size are adjusted to adjust the lateral resolution of detecting the molten pool morphology.

7. A welding pool morphology detection device, configured to perform a welding pool morphology detection method according to any one of claims 1 to 6, characterized in that: It includes a thermal insulation wedge for placing the parent material, a pulsed laser, a data acquisition card and a control unit; The pulsed laser is used to irradiate specific areas on the lower surface of the insulation wedge to form multiple rows of light spots in sequence. The light spot position generates an ultrasonic signal and transmits it through the insulation wedge to the base material molten pool to form a reflection signal; The data acquisition card is used to synchronously collect the reflected signal of each ultrasonic signal in a specific area on the lower surface of the thermal insulation wedge and send it to the control unit; The control unit is used to obtain the ultrasonic velocity of the reflected signal in the relevant medium in the propagation path and the arrival time of the peak of the reflected signal, and calculate the three-dimensional morphology of the internal contour of the molten pool, the three-dimensional morphology of the upper surface of the molten pool, the three-dimensional morphology of the keyhole contour and the three-dimensional morphology of the bubble.

8. The device for detecting the morphology of a welding pool according to claim 7, characterized in that: It also includes a first optical path system, a second optical path system, a laser interferometer, a high-temperature resistant ultrasonic coupling agent and an infrared temperature measurement system. The upper surface of the insulating wedge is tightly connected to the base material through the high-temperature resistant ultrasonic coupling agent. The pulsed laser is used to shape the excitation laser through the first optical path system and irradiate a specific area on the lower surface of the insulating wedge to generate an ultrasonic signal. The ultrasonic signal is transmitted through the insulating wedge through the high-temperature resistant ultrasonic coupling agent to the base material molten pool to form a reflected signal. The laser interferometer is used to generate a detection laser and detect the reflected signal at the corresponding position on the lower surface of the insulating wedge through the second optical path system. The infrared temperature measurement system is used to measure the surface temperature of the molten pool and send it to the control unit to establish a stepped sound velocity in the molten pool, base material and bubbles.

9. A welding device, characterized in that: It includes a welding pool morphology detection device as described in claim 7 or 8.

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