A laser welding device and method capable of monitoring weld penetration in real time

Abstract

The present application relates to the technical field of laser welding, and discloses a laser welding device and method capable of monitoring welding penetration in real time, which comprises a nozzle installed at the output end of a welding gun, a main flow channel facing a molten pool is formed in the nozzle, a secondary flow channel is formed on the outer side of the main flow channel, a mounting plate is arranged on the periphery of the nozzle, an extension piece is arranged on the mounting plate, a mounting ring is arranged at the output end of the extension piece, an air extraction ring is rotatably mounted at the bottom of the mounting ring, and an air extraction pump is mounted on the mounting plate. The main flow channel and the secondary flow channel in the nozzle are arranged, and the negative pressure suction effect at the air extraction ring is used, so that the protective gas sprayed from the secondary flow channel forms an inverted umbrella-shaped air curtain above the molten pool. After the molten metal particles splashed during welding collide with the inverted umbrella-shaped air curtain, the direction of the molten metal particles is deflected, and the molten metal particles move towards the air extraction ring under the traction of the negative pressure air flow, so that the measurement light path of the FMCW laser radar sensor is effectively prevented from being blocked or scattered by the splashed particles, and false echo interference is significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and specifically to a laser welding device and method capable of real-time monitoring of weld penetration depth. Background Technology

[0002] Laser welding technology, due to its advantages such as high energy density, narrow heat-affected zone, and high welding speed, has been widely used in precision manufacturing fields such as automotive manufacturing, aerospace, and electronic packaging. During laser welding, a high-energy laser beam is focused on the workpiece surface, causing the material to melt rapidly and form a transient molten pool. The depth of the molten pool (i.e., penetration depth) is a key process parameter determining the mechanical properties and service reliability of the welded joint. Insufficient penetration depth will lead to a reduction in the effective load-bearing cross-section, decreased joint strength, and a higher risk of fatigue fracture or structural loosening; excessive penetration depth may burn through thin-walled workpieces, causing material spatter and waste, and even damaging the overall structural integrity of the product. Therefore, online and accurate monitoring of penetration depth is of great significance for closed-loop control of welding quality.

[0003] Currently, existing technologies employ frequency-modulated continuous wave (FMCW) lidar sensors to achieve online weld depth measurement. The basic principle is as follows: the sensor emits a measurement beam into the molten pool area and receives the echo signals reflected or scattered by the surface and internal interfaces of the molten pool. By analyzing the frequency or phase difference of the echo signals, the weld depth information is calculated and transmitted to the control unit for real-time adjustment of welding parameters. This non-contact optical measurement method has the advantages of fast response and high resolution, meeting the needs of dynamic monitoring to a certain extent.

[0004] However, actual welding processes are accompanied by intense spattering—high-temperature molten metal particles are ejected from the molten pool. These spatter particles are randomly distributed in both space and time. When they pass through the measurement optical path, they can block or strongly scatter the measurement beam, generating instantaneous false echoes unrelated to the reflection from the actual molten pool. When such interference signals are received by the sensor, they will cause significant spike errors in the depth calculation results, causing the monitoring data to deviate from the actual weld depth value. Existing FMCW lidar measurement systems lack effective means to suppress spatter interference, and the control unit has difficulty distinguishing between the real molten pool signal and the false spatter signal. Therefore, misjudgments are prone to occur during periods of frequent spattering, affecting the accuracy of welding quality assessment and the reliability of control decisions, thus limiting the further promotion and application of this monitoring method in industrial settings. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a laser welding device and method that can monitor the weld penetration depth in real time, thereby suppressing welding spatter interference and achieving accurate real-time online monitoring of the weld penetration depth.

[0006] The objective of this invention can be achieved through the following technical solutions: A laser welding device capable of real-time monitoring of weld penetration depth includes a welding torch, a welding laser module installed inside the welding torch, an FMCW lidar sensor, and a control module. It also includes a nozzle installed at the output end of the welding torch. The nozzle has a main flow channel facing the molten pool and a secondary flow channel located outside the main flow channel. The secondary flow channel is annular and coaxial with the main flow channel. A mounting plate is provided around the nozzle, and a telescopic component is provided on the mounting plate. A mounting ring is provided at the output end of the telescopic component. A suction ring is rotatably mounted at the bottom of the mounting ring, and the suction ring communicates with the interior of the mounting ring through a through hole. A suction pump is mounted on the mounting plate and is connected to the mounting ring through a connecting pipe.

[0007] As a further aspect of the present invention: a turbine fan is provided inside the suction ring, and a driving component for driving the suction ring to rotate is installed on the mounting ring.

[0008] As a further aspect of the present invention: the FMCW lidar sensor is used to emit measurement light into the molten pool and receive echo signals, and the control module is electrically connected to the FMCW lidar sensor, the telescopic component, and the drive component.

[0009] As a further aspect of the present invention: the control module adjusts the extension length of the telescopic component and the rotation speed of the drive component in real time based on the penetration depth data measured by the FMCW laser radar sensor.

[0010] As a further aspect of the present invention: a protective net is provided on the inner side of the suction ring, and the protective net has a ring-shaped mesh structure.

[0011] As a further aspect of the present invention: a number of cleaning brushes and cleaning shovels are evenly distributed circumferentially on the inner side of the mounting ring, the bristles of the cleaning brushes and the blades of the cleaning shovels are elastically fitted to the surface of the protective net, and an annular collection ring is installed at the bottom of the inner ring of the suction ring.

[0012] As a further aspect of the present invention, the mounting ring is provided with a plurality of guide rods that longitudinally penetrate the mounting plate.

[0013] A laser welding method capable of real-time monitoring of weld penetration depth, the method being applied to the laser welding apparatus described above for real-time monitoring of weld penetration depth, the method comprising the following steps: Step S1: Equipment preparation and parameter initialization, start the welding laser module and introduce protective gas into the nozzle, and at the same time start the vacuum pump to create negative pressure in the inner ring of the vacuum ring; Step S2: Welding start-up and gas protection. The welding laser module emits laser to perform welding. The main channel sprays out protective gas and blows it toward the molten pool. The gas sprayed out of the secondary channel is subjected to negative pressure to form an inverted umbrella-shaped air curtain, which deflects the spatter particles and moves them toward the suction ring. Step S3: Spiral airflow assists deflection. The driving component drives the suction ring to rotate. The turbine fan turns the negative pressure airflow into spiral airflow, which applies tangential force to the splashing particles to accelerate deflection. The particles are blocked by the protective net and fall into the collection ring. The gas is discharged through the through hole and connecting pipe. Step S4: Real-time monitoring and feedback adjustment of melt depth. The FMCW laser radar sensor emits measurement light into the molten pool and receives echo signals. The control module adjusts the extension length of the telescopic component and the rotation speed of the drive component in real time according to the measured melt depth. Step S5: Anti-clogging self-cleaning maintenance. When the suction ring rotates, the cleaning brush and cleaning shovel continuously clean the surface of the protective net, scraping the attached particles off to the collection ring to keep the protective net clear.

[0014] The beneficial effects of this invention are: (1) By setting the main flow channel and the secondary flow channel in the nozzle, and with the negative pressure suction effect at the suction ring, the protective gas sprayed from the secondary flow channel forms an inverted umbrella-shaped air curtain above the molten pool. The molten metal particles of welding spatter deflect in direction after colliding with the inverted umbrella-shaped air curtain, and move towards the suction ring under the traction of the negative pressure airflow. This effectively avoids spatter particles from blocking or scattering the measurement optical path of the FMCW laser radar sensor, significantly reduces false echo interference, and ensures the accuracy and reliability of the melt depth monitoring data.

[0015] (2) This invention sets up a turbine fan in the suction ring and configures a drive component to drive the suction ring to rotate, so that the negative pressure airflow is transformed into a spiral airflow. Based on the negative pressure traction, a tangential force is applied to the splash particles, which can easily deflect the movement direction of the splash particles and further reduce the movement speed of the splash particles, thereby more effectively preventing the splash particles from entering the measurement optical path and greatly improving the anti-interference capability of melt depth monitoring.

[0016] (3) The present invention adjusts the extension length of the telescopic component and the rotation speed of the drive component in real time according to the melt depth data measured by the FMCW laser radar sensor through the control module. When the melt depth increases, the telescopic component is automatically controlled to contract so that the tilt angle of the umbrella-shaped air curtain increases. When the melt depth decreases, the telescopic component is automatically controlled to extend so that the tilt angle of the umbrella-shaped air curtain decreases. At the same time, the rotation speed of the drive component is adjusted according to the change of melt depth to change the intensity of the spiral airflow. This achieves a dynamic balance between the ability to deflect splashed particles and energy consumption, and achieves the technical effect of on-demand adjustment and energy saving.

[0017] (4) The present invention provides a protective net inside the suction ring and a cleaning brush and a cleaning shovel are distributed circumferentially inside the installation ring. The bristles of the cleaning brush and the blade of the cleaning shovel are elastically attached to the surface of the protective net. During the rotation of the suction ring, the surface of the protective net is continuously cleaned, avoiding splashed particles from clogging the mesh and ensuring the long-term stability of the negative pressure suction of the suction ring. At the same time, the cleaning particles are collected in a concentrated manner through the collection ring, avoiding secondary pollution. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the nozzle cross-sectional structure in this invention; Figure 3 This is a schematic diagram of the gas flow path in this invention; Figure 4 This is a schematic diagram of the mounting ring structure in this invention; Figure 5 This is a schematic diagram of the internal structure of the suction ring in this invention.

[0020] In the picture: 1. Welding torch; 2. Nozzle; 21. Main flow channel; 22. Secondary flow channel; 3. Mounting plate; 4. Telescopic component; 5. Mounting ring; 51. Guide rod; 52. Cleaning brush; 53. Cleaning shovel; 6. Evacuation ring; 61. Through hole; 62. Turbine fan; 63. Collection ring; 7. Evacuation pump; 71. Connecting pipe; 8. Drive component; 9. Protective net; 10. Welding laser module; 11. FMCW laser radar sensor; 12. Control module. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figures 1-5 As shown, a laser welding device capable of real-time monitoring of weld penetration depth includes a welding torch 1, a welding laser module 10 installed inside the welding torch 1, an FMCW laser radar sensor 11, and a control module 12. It also includes a nozzle 2 installed at the output end of the welding torch 1. The nozzle 2 has a main flow channel 21 facing the molten pool and a secondary flow channel 22 located outside the main flow channel 21. The secondary flow channel 22 is annular and coaxial with the main flow channel 21. A mounting plate 3 is provided around the nozzle 2. A telescopic component 4 is provided on the mounting plate 3. A mounting ring 5 is provided at the output end of the telescopic component 4. Several guide rods 51 extending longitudinally through the mounting plate 3 are provided on the mounting ring 5. A vacuum ring 6 is rotatably mounted at the bottom of the mounting ring 5. The vacuum ring 6 communicates with the interior of the mounting ring 5 through a through hole 61. A vacuum pump 7 is mounted on the mounting plate 3 and communicates with the mounting ring 5 through a connecting pipe 71.

[0023] In practical application of this embodiment, during the welding process, the welding laser module 10 inside the welding torch 1 emits a laser beam into the nozzle 2. Then, the welding torch 1 is held to weld the metal, while inert shielding gas is introduced into the nozzle 2. Part of the gas is blown directly into the molten pool through the main flow channel 21 to protect the weld. At the same time, another part of the gas enters the secondary flow channel 22 and is sprayed towards the molten pool. The sprayed gas forms an outer layer of gas curtain above the molten pool, which does not conflict with the gas in the inner ring. Simultaneously, the vacuum pump 7 is started, and through the connecting pipe 71 and the mounting ring 5, the inner ring of the vacuum ring 6 is in a negative pressure state. Thus, the outer layer of gas sprayed from the secondary flow channel 22 forms a negative pressure. The air curtain will move outward and tilt upward, forming an inverted umbrella-shaped air curtain. During welding, the molten metal particles that splash will move obliquely upward (because the gas ejected from the main channel 21 forms a keyhole at the molten pool, most of the metal particles will only move obliquely upward), and then collide with the inverted umbrella-shaped air curtain. This will cause the splashed particles to deflect in the tilt direction of the umbrella-shaped air curtain. Combined with the velocity of the particles themselves and the negative pressure airflow generated at the suction ring 6, the particles will move in the direction of the suction ring 6, thereby effectively preventing the splashed particles from blocking or scattering the measurement light of the FMCW laser radar sensor 11, ensuring the accuracy of the weld depth monitoring.

[0024] Furthermore, a turbine fan 62 is provided inside the extraction ring 6, and a drive component 8 for driving the extraction ring 6 to rotate is installed on the mounting ring 5.

[0025] In practical applications, during welding, the driving component 8 drives the suction ring 6 to rotate, causing the turbine fan 62 to rotate as well. The rotation of the turbine fan 62 creates a spiral airflow under negative pressure. Based on the negative pressure traction, a tangential force is applied to the spatter particles. This easily deflects the movement direction of the spatter particles and further reduces their speed, thereby effectively preventing the spatter particles from blocking or scattering the measurement light of the FMCW lidar sensor 11 and ensuring the accuracy of weld depth monitoring.

[0026] Furthermore, the FMCW lidar sensor 11 is used to emit measurement light into the molten pool and receive echo signals. The control module 12 is electrically connected to the FMCW lidar sensor 11, the telescopic component 4, and the drive component 8.

[0027] The control module 12 adjusts the extension length of the telescopic component 4 and the rotation speed of the drive component 8 in real time based on the penetration depth data measured by the FMCW laser radar sensor 11.

[0028] In practical applications, during the welding process, the FMCW laser radar sensor 11 emits measuring light to the molten pool in real time and receives echo signals, transmitting the signals to the control module 12 to calculate the weld depth. When the weld depth increases, the welding energy is greater, and the molten pool spatter particles move faster, cover a wider area, and have a larger angle of inclination. At this time, the control module 12 controls the telescopic component 4 to retract, causing the suction ring 6 to move upward, increasing the tilt angle of the umbrella-shaped air curtain. At a larger tilt angle, the high-speed spatter particles can be easily deflected with minimal impact or traction. Combined with the particle's own speed, negative pressure traction, and tangential force, they can quickly move towards the suction ring 6, thus quickly moving away from the measuring light. This eliminates the need to increase the suction force of the suction pump 7 to achieve particle deflection, thereby reducing energy consumption. When the weld depth decreases, the control module 12 controls the telescopic component 4 to extend, causing the suction ring 6 to move downward, decreasing the tilt angle of the umbrella-shaped air curtain. Similarly, a smaller suction force is sufficient to meet the deflection requirements, achieving energy-saving control with on-demand adjustment. Meanwhile, when the melting depth varies greatly, the control module 12 adjusts the rotation speed of the drive component 8 according to the melting depth. When the melting depth is large and the splashing speed is fast, the rotation speed of the suction ring 6 is increased to enhance the intensity of negative pressure and spiral airflow. When the melting depth is small, the rotation speed is reduced to further save energy.

[0029] like Figures 2-5 As shown, a protective net 9 is provided on the inner side of the suction ring 6, and the protective net 9 has a ring-shaped mesh structure.

[0030] The inner side of the installation ring 5 is evenly spaced with several cleaning brushes 52 and cleaning shovels 53. The bristles of the cleaning brushes 52 and the blades of the cleaning shovels 53 are elastically attached to the surface of the protective net 9. The bottom of the inner ring of the suction ring 6 is equipped with an annular collection ring 63.

[0031] In practical application, when the splashed particles move to the protective net 9 with the airflow, some of them are blocked by the protective net 9 and fall into the collection ring 63 below for collection. The airflow is discharged through the through hole 61 and the connecting pipe 71 via the suction pump 7. During the rotation of the suction ring 6, the cleaning brush 52 and cleaning shovel 53 on the inner side of the mounting ring 5 continuously contact the surface of the protective net 9, cleaning the particles attached to the protective net 9 and letting them fall into the collection ring 63, thereby ensuring the permeability and stable suction of the protective net 9.

[0032] Working principle: During welding, the welding laser module 10 inside the welding torch 1 emits a laser beam, which is directed towards the workpiece surface through the main flow channel 21 of the nozzle 2 to form a molten pool. Simultaneously, inert shielding gas is introduced into the nozzle 2. Part of the gas is blown directly onto the molten pool through the main flow channel 21 to provide weld protection, while the other part enters the secondary flow channel 22 and is ejected towards the molten pool, forming an outer air curtain above it. At the same time, the vacuum pump 7 is activated, creating a negative pressure state on the inner ring of the vacuum ring 6 through the connecting pipe 71 and the mounting ring 5. The outer air curtain ejected from the secondary flow channel 22 is affected by this negative pressure, moving outwards and tilting upwards to form an inverted umbrella-shaped air curtain. The driving component 8 drives the vacuum ring 6 to rotate, causing the turbine fan 62 to rotate, transforming the negative pressure airflow into a spiral airflow, applying tangential force to the spatter particles.

[0033] The FMCW lidar sensor 11 emits measurement light into the molten pool in real time and receives echo signals, transmitting the signals to the control module 12 to calculate the melt depth. When the melt depth increases, the control module 12 controls the telescopic component 4 to retract, causing the mounting ring 5 and the suction ring 6 to move upward along the guide rod 51, increasing the tilt angle of the inverted umbrella-shaped air curtain, allowing high-speed splashing particles to easily deflect at a larger tilt angle. At the same time, the control module 12 increases the rotation speed of the drive component 8 to enhance the spiral airflow intensity. When the melt depth decreases, the control module 12 controls the telescopic component 4 to extend, causing the suction ring 6 to move downward, reducing the tilt angle of the air curtain, and simultaneously reducing the rotation speed of the drive component 8 to save energy.

[0034] Splashing particles are carried by the airflow to the protective net 9 and are blocked. Some particles fall into the collection ring 63 and are collected. The airflow is discharged by the suction pump 7 through the through hole 61 and the connecting pipe 71. During the rotation of the suction ring 6, the cleaning brush 52 and cleaning shovel 53 on the inner side of the mounting ring 5 are in continuous contact with the surface of the protective net 9, cleaning the attached particles into the collection ring 63, ensuring the permeability of the protective net 9.

[0035] A laser welding method capable of real-time monitoring of weld penetration depth, the method being applied to the laser welding apparatus described above for real-time monitoring of weld penetration depth, the method comprising the following steps: Step S1: Device preparation and parameter initialization, start the welding laser module 10 and introduce protective gas into the nozzle 2, and at the same time start the vacuum pump 7 to create a negative pressure in the inner ring of the vacuum ring 6; Step S2: Welding start and gas protection. The welding laser module 10 emits a laser to perform welding. The main channel 21 sprays out protective gas and blows it toward the molten pool. The gas sprayed out by the secondary channel 22 is subjected to negative pressure to form an inverted umbrella-shaped air curtain, which deflects the spatter particles and moves them toward the suction ring 6. Step S3: Spiral airflow assists deflection. Driven by the drive unit 8, the suction ring 6 rotates. The turbine fan 62 transforms the negative pressure airflow into a spiral airflow, applying tangential force to the splashing particles to accelerate deflection. The particles are blocked by the protective net 9 and fall into the collection ring 63. The gas is discharged through the through hole 61 and the connecting pipe 71. Step S4: Real-time monitoring and feedback adjustment of melt depth. The FMCW laser radar sensor 11 emits measurement light to the molten pool and receives echo signals. The control module 12 adjusts the extension length of the telescopic component 4 and the rotation speed of the drive component 8 in real time according to the measured melt depth. Step S5: Anti-clogging self-cleaning maintenance. When the suction ring 6 rotates, the cleaning brush 52 and cleaning shovel 53 continuously clean the surface of the protective net 9, scraping the attached particles off to the collection ring 63, keeping the protective net 9 transparent.

Claims

1. A laser welding device capable of real-time monitoring of weld penetration depth, comprising a welding torch (1), a welding laser module (10) installed inside the welding torch (1), an FMCW laser radar sensor (11), and a control module (12), characterized in that, It also includes a nozzle (2) installed at the output end of the welding torch (1). The nozzle (2) has a main flow channel (21) facing the molten pool and a secondary flow channel (22) opened outside the main flow channel (21). The secondary flow channel (22) is annular and coaxial with the main flow channel (21). A mounting plate (3) is provided around the nozzle (2). A telescopic component (4) is provided on the mounting plate (3). A mounting ring (5) is provided at the output end of the telescopic component (4). A suction ring (6) is rotatably installed at the bottom of the mounting ring (5). The suction ring (6) is connected to the inside of the mounting ring (5) through a through hole (61) opened on it. A suction pump (7) is installed on the mounting plate (3). The suction pump (7) is connected to the mounting ring (5) through a connecting pipe (71).

2. The laser welding device capable of real-time monitoring of weld penetration depth according to claim 1, characterized in that, The vacuum ring (6) is equipped with a turbine fan (62), and a drive component (8) for driving the vacuum ring (6) to rotate is installed on the mounting ring (5).

3. The laser welding device capable of real-time monitoring of weld penetration depth according to claim 2, characterized in that, The FMCW lidar sensor (11) is used to emit measurement light into the molten pool and receive echo signals. The control module (12) is electrically connected to the FMCW lidar sensor (11), the telescopic component (4), and the drive component (8).

4. The laser welding apparatus for real-time monitoring of weld penetration depth according to claim 3, characterized in that, The control module (12) adjusts the extension length of the telescopic component (4) and the rotation speed of the drive component (8) in real time based on the melting depth data measured by the FMCW laser radar sensor (11).

5. The laser welding apparatus for real-time monitoring of weld penetration depth according to claim 2, characterized in that, The inner side of the air extraction ring (6) is provided with a protective net (9), which is a ring-shaped mesh structure.

6. The laser welding apparatus for real-time monitoring of weld penetration depth according to claim 5, characterized in that, The mounting ring (5) has several cleaning brushes (52) and cleaning shovels (53) evenly distributed on the inner circumferential side. The bristles of the cleaning brushes (52) and the blades of the cleaning shovels (53) are elastically attached to the surface of the protective net (9). The bottom of the inner ring of the suction ring (6) is equipped with an annular collection ring (63).

7. The laser welding apparatus for real-time monitoring of weld penetration depth according to claim 1, characterized in that, The mounting ring (5) is provided with several guide rods (51) that penetrate the mounting plate (3) longitudinally.

8. A laser welding method capable of real-time monitoring of weld penetration, characterized in that, The method is applied to a laser welding apparatus capable of real-time monitoring of weld penetration depth as described in any one of claims 1-7, and the method includes the following steps: Step S1: Device preparation and parameter initialization, start the welding laser module (10) and introduce protective gas into the nozzle (2), and at the same time start the vacuum pump (7) to form a negative pressure in the inner ring of the vacuum ring (6); Step S2: Welding start and gas protection. The welding laser module (10) emits a laser to perform welding. The main channel (21) sprays out protective gas and blows it toward the molten pool. The gas sprayed out by the secondary channel (22) is subjected to negative pressure to form an inverted umbrella-shaped air curtain, which deflects the spatter particles and moves them toward the suction ring (6). Step S3: Spiral airflow assists deflection. The driving component (8) drives the suction ring (6) to rotate. The turbine fan (62) turns the negative pressure airflow into a spiral airflow, applying tangential force to the splashing particles to accelerate deflection. The particles are blocked by the protective net (9) and fall into the collection ring (63). The gas is discharged through the through hole (61) and the connecting pipe (71). Step S4: Real-time monitoring and feedback adjustment of melt depth. The FMCW laser radar sensor (11) emits measurement light to the molten pool and receives echo signals. The control module (12) adjusts the extension length of the telescopic component (4) and the rotation speed of the drive component (8) in real time according to the measured melt depth. Step S5: Anti-clogging self-cleaning maintenance. When the suction ring (6) rotates, the cleaning brush (52) and cleaning shovel (53) continuously clean the surface of the protective net (9), scraping the attached particles off to the collection ring (63) to keep the protective net (9) transparent.

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