A magnetic field regulating device and method for dissimilar material laser welding

Abstract

The present application relates to the technical field of welding, in particular to a magnetic field regulating device and method for laser welding of dissimilar materials. The laser welding magnetic field regulating device comprises a laser welding head, a magnetic field generating system and a protective gas system. The laser welding head is used to output a laser beam to weld two different welding materials. The magnetic field generating system comprises a plurality of coil assemblies and a power supply controller. The current method, current size and current frequency of the coil assemblies are controlled by the power supply controller, thereby changing the type of magnetic field generated by the coil assemblies in the molten pool. A stable or alternating axial, transverse, longitudinal and any asymmetric composite magnetic field can be generated, providing a larger process exploration window with high flexibility and applicability. Since the asymmetric magnetic field can be applied to the characteristic differences of the two sides of the dissimilar materials, the flow, mass transfer, heat transfer and solidification behavior of different areas of the molten pool can be targeted regulated, thereby fundamentally improving the organization non-uniformity problem of dissimilar material welding.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a magnetic field control device and method for laser welding of dissimilar materials. Background Technology

[0002] Laser welding of dissimilar materials (such as dissimilar titanium alloys and titanium alloy-titanium-based composites) is a key technology for achieving lightweight structures, functional integration, and cost reduction. However, this process faces the following challenges: high temperatures coarsen the microstructure of the heat-affected zone (HAZ) of the base materials on both sides; remelting of the base materials disrupts the original microstructure equilibrium; and after rapid solidification of the weld, its microstructure differs significantly from that of the base materials on both sides, easily forming coarse grains, brittle intermetallic compounds, and microstructure inhomogeneity (such as compositional segregation or reinforcing phase agglomeration). These factors lead to a significant decrease in the mechanical properties of the welded joint, especially ductility and fatigue strength, making it prone to fracture at the weld during subsequent processing or service, resulting in the failure of the entire structural component. To improve this problem, magnetic field-assisted laser welding technology has been widely used. As an energy field with fast energy input response, non-contact, and pollution-free, magnetic fields can generate Lorentz forces with conductive fluids such as plasma and molten metal in the welding process. This can control the flow state of the molten pool, improve keyhole stability, promote heat / mass transfer homogenization, thereby suppressing metallurgical defects, improving forming quality, optimizing mechanical properties, and meeting higher quality and more efficient welding requirements.

[0003] Currently, existing technologies mostly use permanent magnets or excitation coils to generate static or alternating magnetic fields, with the magnetic field direction mainly axial, transverse, or longitudinal. These welding devices have the following limitations: the type or direction of the generated magnetic field is singular, making it impossible to flexibly switch according to different welding requirements; the magnetic field generated by existing welding equipment is usually distributed about the weld seam, making it impossible to perform asymmetric and differentiated magnetic field control based on the different physical properties (such as microstructure, coefficient of thermal expansion, melting point, etc.) on both sides of dissimilar materials, and making it difficult to specifically solve problems such as uneven weld structure and metallurgical defects caused by material differences. Summary of the Invention

[0004] This invention provides a magnetic field control device for laser welding of dissimilar materials, which solves the problem that existing technologies have difficulty in effectively addressing the uneven weld structure and metallurgical defects caused by material differences.

[0005] This invention provides a magnetic field control device for laser welding of dissimilar materials, comprising: A laser welding head, wherein the laser welding head is used to output a laser beam to weld the same or two different welding materials; A magnetic field generating system includes multiple coil assemblies and a power controller. The multiple coil assemblies are symmetrically distributed in pairs around the outer periphery of the laser beam with the axis of the laser welding head as the center. The axes of the multiple coil assemblies intersect the axis of the laser beam at the center point of the molten pool. The power controller is electrically connected to the multiple coil assemblies and is used to control the current method, current magnitude, and current frequency of the coil assemblies, thereby changing the type of magnetic field generated by the coil assemblies in the molten pool. A protective gas system for forming a protective gas curtain around the periphery of the molten pool.

[0006] A magnetic field control device for laser welding of dissimilar materials provided by the present invention further includes: An adjustment bracket is connected to the laser welding head, and multiple coil assemblies are disposed on the adjustment bracket.

[0007] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the adjustment bracket comprises: Multiple telescopic frames are arranged symmetrically in pairs, with the upper ends of the multiple telescopic frames connected to the laser welding head; multiple coil assemblies are connected one-to-one to the lower ends of the multiple telescopic frames, and the telescopic frames are used to adjust the height of the coil assemblies.

[0008] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the telescopic frame includes a manually telescopic rod, the fixed end of which is connected to the laser welding head, and the telescopic end of which is connected to the corresponding coil assembly.

[0009] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the telescopic frame includes an electric telescopic rod, the fixed end of the electric telescopic rod is connected to the laser welding head, and the telescopic end of the electric telescopic rod is connected to the corresponding coil assembly.

[0010] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the adjustment bracket further includes: Multiple angle adjustment mechanisms are provided, with each coil assembly connected to the lower end of the corresponding telescopic frame via one of the angle adjustment mechanisms, the angle adjustment mechanisms being used to adjust the axial direction of the coil assembly.

[0011] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the adjustment bracket includes four angle adjustment mechanisms, and the four angle adjustment mechanisms are arranged symmetrically in pairs about the axis of the laser beam.

[0012] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the angle adjustment mechanism includes a hand-tightening bolt, which is connected to the coil assembly and the lower end of the telescopic frame.

[0013] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the angle adjustment mechanism includes a servo motor, the housing of the servo motor is connected to the lower end of the telescopic frame, and the rotating shaft of the servo motor is connected to the coil assembly.

[0014] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the coil assembly comprises: An iron core, which is arranged along the axial direction of the coil assembly and connected to the angle adjustment mechanism; A coil, which is sleeved on the outer periphery of the iron core.

[0015] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the protective gas system comprises: High-purity argon gas source; The main nozzle has an annular flow channel formed between the coil and the iron core, and the end of the annular flow channel away from the angle adjustment mechanism is connected to the main nozzle. A gas pipeline is connected to the high-purity argon gas source and the end of the annular flow channel near the angle adjustment mechanism.

[0016] According to the present invention, a magnetic field control device for laser welding of dissimilar materials is provided, wherein the protective gas system further includes: A nozzle on the back of the weld is located at the bottom of the workbench and is connected to the gas pipeline.

[0017] The present invention also provides a magnetic field control method for laser welding of dissimilar materials, the magnetic field control method being based on the magnetic field control device for laser welding of dissimilar materials described in any one of the above claims, comprising: The initial current parameters were determined based on the physicochemical properties of the two different welding materials. Based on the initial current parameters, the power controller supplies current to the coil assembly; The protective gas system is controlled to operate, thereby cooling the coil and continuously supplying high-purity argon gas to the molten pool to be welded; The laser welding head outputs a laser beam, and the power controller controls the current method, current magnitude, and current frequency of the coil assembly according to the welding requirements, thereby changing the type of magnetic field generated by the coil assembly in the molten pool.

[0018] According to the present invention, a magnetic field control method for laser welding of dissimilar materials includes the step of controlling the current method, current magnitude, and current frequency of the coil assembly through the power controller according to welding requirements, thereby changing the type of magnetic field generated by the coil assembly in the molten pool, comprising: When it is determined that a transverse magnetic field needs to be generated, the current magnitudes of the first, second, third, and fourth coils are all controlled to be the same. The current directions of the first and second coils are the same, and the current directions of the third and fourth coils are the same but opposite to the current direction of the first coil. A transverse magnetic field perpendicular to the plane containing the laser beam and the welding direction is generated at the center of the molten pool. The direction of the magnetic field is +x or -x. When it is determined that a longitudinal magnetic field needs to be generated, the current magnitudes of the first coil, the second coil, the third coil, and the fourth coil are all controlled to be the same. The current directions of the first coil and the fourth coil are the same, and the current directions of the second coil and the third coil are the same but opposite to the current direction of the first coil. A longitudinal magnetic field parallel to the welding direction is generated at the center of the molten pool, and the direction of the magnetic field is +y or -y. When it is determined that an axial magnetic field needs to be generated, the magnitude and direction of the current in the first coil, the second coil, the third coil, and the fourth coil are all controlled to be the same, so as to generate an axial magnetic field parallel to the laser beam axis at the center of the molten pool, with the direction of the magnetic field being +z or -z. When it is determined that an asymmetric magnetic field needs to be generated, the current magnitude and direction of the first coil and the second coil are controlled to be the same, the current magnitude of the third coil and the fourth coil is the same, but different from the current magnitude of the first coil; the current direction of the third coil and the fourth coil is the same, but opposite to the current direction of the first coil; thus generating an asymmetric magnetic field inside the molten pool with a large magnetic field strength on one side and a small magnetic field strength on the other side. Alternatively, the current directions of the first coil and the second coil are controlled to be the same, and the current magnitudes of the first coil and the second coil are different; the current magnitudes of the second coil, the third coil, and the fourth coil are controlled to be the same, and the current directions of the third coil and the fourth coil are the same, but opposite to the current direction of the first coil; thus generating an asymmetric magnetic field inside the molten pool with a large single-angle magnetic field strength and small strengths of the other magnetic fields; When it is determined that a steady magnetic field needs to be generated, the current frequencies of the first coil, the second coil, the third coil, and the fourth coil in the above steps are all controlled to be 0. When it is determined that an alternating magnetic field needs to be generated, the current frequencies of the first coil, the second coil, the third coil, and the fourth coil in the above steps are controlled to be predetermined values, wherein the predetermined values ​​are greater than or equal to zero, and the current frequency of at least one coil is greater than zero. When it is determined that a rotating magnetic field needs to be generated, the current changes of the first coil, the second coil, the third coil, and the fourth coil are controlled to make the direction of the magnetic field at the center of the molten pool continuously change.

[0019] The magnetic field control device for laser welding of dissimilar materials provided by this invention controls the current method, current magnitude, and current frequency of the coil assembly through a power controller, thereby changing the type of magnetic field generated by the coil assembly in the molten pool. It can generate constant or alternating axial, transverse, longitudinal, and arbitrary asymmetric composite magnetic fields, providing a large process exploration window with strong flexibility and applicability. Because it can apply an asymmetric magnetic field to the characteristic differences on both sides of the dissimilar materials, it can specifically control the flow, mass transfer, heat transfer, and solidification behavior in different regions of the molten pool, fundamentally improving the problem of microstructure inhomogeneity in dissimilar material welding. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the magnetic field control device for laser welding of dissimilar materials provided by the present invention.

[0022] Figure 2 This is a schematic diagram of the +x direction magnetic field generated by the four coil assemblies provided by the present invention.

[0023] Figure 3 This is a schematic diagram of the -x direction magnetic field generated by the four coil assemblies provided by the present invention.

[0024] Figure 4 This is a schematic diagram of the +y direction magnetic field generated by the four coil assemblies provided by the present invention.

[0025] Figure 5 This is a schematic diagram of the -y direction magnetic field generated by the four coil assemblies provided by the present invention.

[0026] Figure 6 This is a schematic diagram of the +z direction magnetic field generated by the four coil assemblies provided by the present invention.

[0027] Figure 7 This is a schematic diagram of the -z direction magnetic field generated by the four coil assemblies provided by the present invention.

[0028] Figure 8 This is a schematic diagram of a one-sided asymmetric magnetic field provided by the present invention.

[0029] Figure 9 This is a schematic diagram of a single-angle asymmetric magnetic field provided by the present invention.

[0030] Figure label: 10. Laser welding head; 11. Laser beam; 20. Coil assembly; 21. First coil; 22. Second coil; 23. Third coil; 24. Fourth coil; 30. Adjustment bracket; 31. Telescopic frame; 40. Main nozzle. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0034] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0036] like Figure 1 As shown, the magnetic field control device for laser welding of dissimilar materials includes a laser welding head 10, a magnetic field generating system, and a shielding gas system. The laser welding head 10 is used to output a laser beam 11 to weld the same or two different welding materials. The magnetic field generating system includes multiple coil assemblies 20 and a power controller. The multiple coil assemblies 20 are symmetrically distributed in pairs around the axis of the laser welding head 10 on the outer periphery of the laser beam 11, and the axes of the multiple coil assemblies 20 intersect the axis of the laser beam 11 at the center point of the molten pool. The power controller is electrically connected to the multiple coil assemblies 20 and is used to control the current method, current magnitude, and current frequency of the coil assemblies 20, thereby changing the type of magnetic field generated by the coil assemblies 20 in the molten pool. The shielding gas system is used to form a protective gas curtain around the outer periphery of the molten pool.

[0037] The magnetic field control device for laser welding of dissimilar materials provided by this invention controls the current method, current magnitude, and current frequency of the coil assembly 20 through a power controller, thereby changing the type of magnetic field generated by the coil assembly 20 in the molten pool. It can generate stable or alternating axial, transverse, longitudinal, and arbitrary asymmetric composite magnetic fields, providing a large process exploration window with strong flexibility and applicability. Since it can apply an asymmetric magnetic field to the characteristic differences on both sides of the dissimilar materials, it can specifically control the flow, mass transfer, heat transfer, and solidification behavior in different regions of the molten pool, fundamentally improving the problem of non-uniform microstructure in dissimilar material welding.

[0038] In one embodiment of the present invention, the magnetic field control device for laser welding of dissimilar materials further includes an adjustment bracket 30, which is connected to the laser welding head 10. Multiple coil assemblies 20 are mounted on the adjustment bracket 30. The adjustment bracket 30 is used to adjust the height and axial direction of each coil assembly 20, enabling precise adjustment of the spatial position and orientation of each coil assembly 20. This ensures that the axes of the multiple coil assemblies 20 always precisely intersect the axis of the laser beam 11 at the center point of the molten pool. This precise adjustment ensures that the generated magnetic field acts most effectively on the core region of the molten pool, providing conditions for flexibly applying transverse, longitudinal, axial, and even asymmetric magnetic fields according to different welding requirements. This allows for targeted and effective control of the flow, heat transfer, and solidification behavior in different regions of the molten pool, ultimately improving the problem of non-uniform microstructure in dissimilar material welding.

[0039] In one embodiment of the present invention, the adjusting bracket 30 includes multiple telescopic brackets 31, the number of which is even, and the multiple telescopic brackets 31 are arranged symmetrically in pairs. The symmetrical arrangement of the telescopic brackets 31 in pairs ensures that the magnetic fields generated by each coil assembly 20 are evenly and symmetrically superimposed in the central region of the molten pool, avoiding unstable unidirectional flow or splashing of the molten pool metal that may be caused by uneven magnetic field distribution, thereby significantly ensuring the stability and effectiveness of the magnetic field control process. The upper ends of the multiple telescopic brackets 31 are connected to the laser welding head 10. By integrating the adjusting bracket 30 and the laser welding head 10 into one unit, it can be ensured that the magnetic field control device can move synchronously with the laser beam 11. When welding complex weld paths, the precise relative position of the coil assembly 20 and the molten pool remains unchanged, greatly simplifying the control system and improving the positioning accuracy and reliability in the automated welding process; of course, the upper ends of the telescopic brackets 31 can also be fixed by a separate fixed bracket. Multiple coil assemblies 20 are connected one-to-one to the lower ends of multiple telescopic frames 31. The telescopic frames 31 are used to adjust the height of the coil assemblies 20. The synchronous extension and retraction of the telescopic frames 31 enables precise adjustment of the overall height of all coil assemblies 20 to meet the welding requirements of workpieces of different thicknesses. It also provides the possibility of independent fine adjustment of the height of each coil, ensuring that the magnetic field focus can be accurately aligned with the center of the molten pool, thereby achieving optimal control of the fluid behavior inside the molten pool.

[0040] In one embodiment of the present invention, the telescopic frame 31 includes a manual telescopic rod. The fixed end of the manual telescopic rod is connected to the laser welding head 10, and the telescopic end of the manual telescopic rod is connected to the corresponding coil assembly 20. The advantage of using a manual adjustment method is that its mechanical structure is simple, its manufacturing cost is low, and its reliability is high. Stable and reliable height adjustment can be achieved without the need for an additional complex electrical control system, greatly reducing equipment failure rate and maintenance difficulty. Specifically, the manual telescopic rod is a telescopic locking rod or a combination of a nut and a screw. During use, the height of the coil assembly 20 can be adjusted manually.

[0041] In one embodiment of the present invention, the telescopic frame 31 includes an electric telescopic rod. The fixed end of the electric telescopic rod is connected to the laser welding head 10, and the telescopic end of the electric telescopic rod is connected to the corresponding coil assembly 20. The electric adjustment method enables automated control of the height of the coil assembly 20, which not only greatly improves the accuracy and repeatability of the adjustment and avoids errors that may be caused by manual operation, but also allows the magnetic field control system to be seamlessly integrated into the entire automated welding workstation. The electric telescopic rod can be a lead screw module or an electric push rod, etc. Using the electric telescopic rod allows for precise adjustment of the height of the coil assembly 20. This not only ensures that the magnetic field focus is precisely set at the optimal position in the molten pool before welding, but more importantly, it provides the possibility of dynamically and in real-time adjusting the depth of the magnetic field focus during the welding process according to process requirements. This allows for more refined proactive intervention and optimization of the metallurgical behavior of the molten pool to adapt to the needs of different welding stages, ultimately significantly improving the forming quality and mechanical properties of dissimilar material welded joints.

[0042] In one embodiment of the present invention, the adjusting bracket 30 further includes a plurality of angle adjusting mechanisms. Each coil assembly 20 is connected to the lower end of the corresponding telescopic frame 31 through an angle adjusting mechanism. The angle adjusting mechanism is used to adjust the axial direction of the coil assembly 20.

[0043] The adjustment bracket 30 also includes multiple angle adjustment mechanisms. Each coil assembly 20 is connected to the lower end of the corresponding telescopic frame 31 through an angle adjustment mechanism. By adding an angle adjustment function to the height adjustment mechanism, the attitude adjustment of each coil assembly 20 can be realized, thus structurally ensuring that the magnetic field control system has complete adjustment freedom in three-dimensional space. The angle adjustment mechanism is used to adjust the axial direction of the coil assembly 20, so that the magnetic field can be precisely oriented towards the center of the molten pool. It is a key component to ensure that the magnetic field axes of all coils precisely intersect at one point. By precisely adjusting the axial direction of each coil, the magnetic field can be precisely focused, and the magnetic force can be most effectively concentrated inside the molten pool.

[0044] In one embodiment of the present invention, the adjustment bracket 30 includes four angle adjustment mechanisms, which are arranged symmetrically in pairs about the axis of the laser beam 11. Four coil assemblies 20 are positioned in the four quadrants of the laser welding head 10, employing an orthogonal symmetrical layout. This arrangement provides conditions for flexible construction and precise control of the magnetic field. By independently or in combination energizing one pair of coils (e.g., in the X-axis direction) or another pair of coils (in the Y-axis direction) in relative positions, a pure transverse magnetic field along a specific direction (e.g., perpendicular or parallel to the welding direction) can be easily generated in the molten pool. Furthermore, by energizing the four coil assemblies 20 according to a program, a rotating magnetic field can be efficiently generated. This ability to generate transverse, rotating, and even arbitrary composite magnetic fields on demand allows the device to implement optimized molten pool stirring, flow control, and solidification structure refinement strategies for different combinations of dissimilar materials and their welding difficulties. This greatly expands the application range and process adaptability of the equipment, providing a powerful and universal platform for solving various dissimilar material welding problems.

[0045] In one embodiment of the present invention, the angle adjustment mechanism includes a hand-tightening bolt, which is connected to the lower end of the coil assembly 20 and the telescopic frame 31. When it is necessary to adjust the direction of the coil assembly 20, the hand-tightening bolt is loosened, the direction of the coil assembly 20 is adjusted, and after adjusting to a suitable position, the hand-tightening bolt is tightened.

[0046] In one embodiment of the present invention, the angle adjustment mechanism includes a servo motor, the housing of which is connected to the lower end of the telescopic frame 31, and the rotating shaft of the servo motor is connected to the coil assembly 20. Using a servo motor as the driving element for angle adjustment not only allows for precise setting of the initial angle before welding to align with the center of the molten pool, but also provides the possibility of dynamically adjusting the direction of the magnetic field during welding based on a preset program or real-time feedback. For example, it enables the reciprocating oscillation or rotation of the magnetic field, thereby allowing for the implementation of more complex and refined molten pool control strategies.

[0047] In one embodiment of the present invention, the coil assembly 20 includes an iron core and coils, each of which is an excitation coil. Each coil is independently connected to a programmable, multi-channel power controller, enabling partitioning and independent control of multiple coils. This allows for the flexible construction of complex magnetic fields. The controller can programmatically control the current direction, magnitude, and frequency of each coil, allowing for precise adjustment and rapid response to changes in magnetic field strength, polarity, and dynamics. This significantly improves the accuracy and real-time performance of magnetic field control, adapting to different application scenarios. The iron core is positioned along the axial direction of the coil assembly 20 and connected to an angle adjustment mechanism. The coils are fitted around the outer periphery of the iron core. Utilizing the high permeability of the iron core, magnetic lines of force can be effectively concentrated within the core, significantly enhancing the magnetic field strength under the same current and improving energy conversion efficiency. This allows the device to generate a stronger magnetic field effect with lower energy consumption.

[0048] In one embodiment of the present invention, the protective gas system includes a high-purity argon gas source, a main nozzle 40, and a gas pipeline. High-purity argon gas is used as the protective medium. Utilizing its chemical inertness, it can effectively isolate reactive gases such as oxygen, nitrogen, and hydrogen in the air from contact with the high-temperature molten pool, fundamentally eliminating harmful metallurgical reactions such as oxidation, nitriding, and hydrogenation, thereby ensuring the purity and intrinsic quality of the final product. An annular flow channel is formed between the coil and the iron core, achieving a high degree of spatial integration and simplifying the overall structure of the equipment. The end of the annular flow channel away from the angle adjustment mechanism is connected to the main nozzle 40, and the outlet direction of the main nozzle 40 points towards the center of the molten pool. This allows the protective gas flow to be concentrated and stably delivered to the core area of ​​the molten pool that needs the most protection, improving the gas utilization efficiency and achieving a comprehensive protective effect with a more economical gas flow rate. The gas pipeline is connected to the high-purity argon gas source and the end of the annular flow channel near the angle adjustment mechanism.

[0049] Argon gas from a high-purity argon source is delivered to the annular flow channel via gas pipelines and finally ejected through the main nozzle 40. The argon gas exiting the main nozzle 40 forms a fully enveloping, dead-angle-free protective gas curtain, covering the entire molten pool area. This all-round, three-dimensional gas curtain protection ensures that there are no blind spots on the molten pool surface, providing a stable and pure local atmosphere environment for the entire melting and solidification process. This is crucial for preventing local defects and improving the uniformity and yield of products (such as welds and crystals). Simultaneously, as the argon gas passes through the annular flow channel, it can exchange heat with and cool the current-carrying coil. The gas flow promptly removes the Joule heat generated during coil operation, forming a highly efficient air-cooling system. This not only effectively avoids the risk of performance degradation or even burnout due to overheating of the coil, ensuring long-term stable operation of the equipment, but also eliminates the risk of leakage compared to water cooling methods, resulting in higher system reliability and safer, more convenient maintenance.

[0050] In one embodiment of the invention, the protective gas system further includes a weld back nozzle, which is disposed at the bottom of the worktable and connected to a gas pipeline. The weld back nozzle is used to spray argon gas upwards to protect the bottom of the molten pool from oxidation.

[0051] like Figures 2 to 9 As shown, the present invention also provides a magnetic field control method for laser welding of dissimilar materials. The magnetic field control method is based on the magnetic field control device for laser welding of dissimilar materials described in any of the above embodiments, and includes: The initial current parameters were determined based on the physicochemical properties of the two different welding materials. The power controller supplies current to the coil assembly 20 based on the initial current parameters; The protective gas system is controlled to operate, thereby cooling the coil and continuously supplying high-purity argon gas to the molten pool to be welded; The laser welding head 10 outputs a laser beam 11, and the power controller controls the current method, current magnitude and current frequency of the coil assembly 20 according to the welding requirements, thereby changing the type of magnetic field generated by the coil assembly 20 in the molten pool.

[0052] In one embodiment of the present invention, the step of controlling the current method, current magnitude, and current frequency of the coil assembly 20 according to welding requirements via a power controller, thereby changing the type of magnetic field generated by the coil assembly 20 in the molten pool, includes: Step (1): When it is determined that a transverse magnetic field needs to be generated, the current magnitudes of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 are all the same. The current directions of the first coil 21 and the second coil 22 are the same, and the current directions of the third coil 23 and the fourth coil 24 are the same but opposite to the current direction of the first coil 21. A transverse magnetic field perpendicular to the plane containing the laser beam 11 and the welding direction is generated at the center of the molten pool. The direction of the magnetic field is +x or -x. Step (2): When it is determined that a longitudinal magnetic field needs to be generated, the current magnitudes of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 are all the same. The current directions of the first coil 21 and the fourth coil 24 are the same, and the current directions of the second coil 22 and the third coil 23 are the same and opposite to the current direction of the first coil 21. A longitudinal magnetic field parallel to the welding direction is generated at the center of the molten pool. The direction of the magnetic field is +y or -y. Step (3): When it is determined that an axial magnetic field needs to be generated, the magnitude and direction of the current of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 are all the same, so that an axial magnetic field parallel to the axis of the laser beam 11 is generated at the center of the molten pool, and the direction of the magnetic field is +z or -z. Step (4): When it is determined that an asymmetric magnetic field needs to be generated, the current magnitude and direction of the first coil 21 and the second coil 22 are the same, the current magnitude of the third coil 23 and the fourth coil 24 are the same, and the current magnitude of the third coil 23 is different from that of the first coil 21; the current direction of the third coil 23 and the fourth coil 24 is the same, and the current direction of the first coil 21 is opposite; thus generating an asymmetric magnetic field with a large magnetic field strength on one side and a small magnetic field strength on the other side inside the molten pool. Alternatively, the current directions of the first coil 21 and the second coil 22 are the same, but the magnitudes of the currents in the first coil 21 and the second coil 22 are different; the magnitudes of the currents in the second coil 22, the third coil 23, and the fourth coil 24 are the same, but the current directions of the third coil 23 and the fourth coil 24 are the same and opposite to the current direction of the first coil 21; thus generating an asymmetric magnetic field inside the molten pool with a large single-angle magnetic field strength and small strengths in the other magnetic fields; When it is determined that a steady magnetic field needs to be generated, the current frequencies of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 in steps (1) to (4) above are all controlled to be 0. When it is determined that an alternating magnetic field needs to be generated, the current frequencies of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 in steps (1) to (4) above are controlled to be predetermined values, wherein the predetermined values ​​are greater than or equal to zero, and the current frequency of at least one coil is greater than zero. When it is determined that a rotating magnetic field needs to be generated, the current changes of the first coil 21, the second coil 22, the third coil 23, and the fourth coil 24 are controlled to continuously change the direction of the magnetic field at the center of the molten pool. For example, the direction of the magnetic field is first set to +z, then switched to +y, then to +x, then to -z, then to -y, and then to -x. The characteristic of this magnetic field is that it avoids the molten fluid, which is in the same direction or opposite direction as the unidirectional magnetic field, from generating an induced current, thus remaining unaffected by the magnetic field.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic field control device for laser welding of dissimilar materials, characterized in that, include: A laser welding head, wherein the laser welding head is used to output a laser beam to weld the same or two different welding materials; A magnetic field generating system includes multiple coil assemblies and a power controller. The multiple coil assemblies are symmetrically distributed in pairs around the outer periphery of the laser beam with the axis of the laser welding head as the center. The axes of the multiple coil assemblies intersect the axis of the laser beam at the center point of the molten pool. The power controller is electrically connected to the multiple coil assemblies and is used to control the current method, current magnitude, and current frequency of the coil assemblies, thereby changing the type of magnetic field generated by the coil assemblies in the molten pool. A protective gas system for forming a protective gas curtain around the periphery of the molten pool.

2. The magnetic field control device for laser welding of dissimilar materials according to claim 1, characterized in that, Also includes: An adjustment bracket is connected to the laser welding head, and multiple coil assemblies are disposed on the adjustment bracket.

3. The magnetic field control device for laser welding of dissimilar materials according to claim 2, characterized in that, The adjustment bracket includes: Multiple telescopic frames are arranged symmetrically in pairs, with the upper ends of the multiple telescopic frames connected to the laser welding head; multiple coil assemblies are connected one-to-one to the lower ends of the multiple telescopic frames, and the telescopic frames are used to adjust the height of the coil assemblies.

4. The magnetic field control device for laser welding of dissimilar materials according to claim 3, characterized in that, The telescopic frame includes a manually telescopic rod, the fixed end of which is connected to the laser welding head, and the telescopic end of which is connected to the corresponding coil assembly.

5. The magnetic field control device for laser welding of dissimilar materials according to claim 3, characterized in that, The telescopic frame includes an electric telescopic rod, the fixed end of which is connected to the laser welding head, and the telescopic end of which is connected to the corresponding coil assembly.

6. The magnetic field control device for laser welding of dissimilar materials according to any one of claims 3 to 5, characterized in that, The adjustment bracket also includes: Multiple angle adjustment mechanisms are provided, with each coil assembly connected to the lower end of the corresponding telescopic frame via one of the angle adjustment mechanisms, the angle adjustment mechanisms being used to adjust the axial direction of the coil assembly.

7. The magnetic field control device for laser welding of dissimilar materials according to claim 6, characterized in that, The adjustment bracket includes four angle adjustment mechanisms, which are arranged symmetrically in pairs about the axis of the laser beam.

8. The magnetic field control device for laser welding of dissimilar materials according to claim 6, characterized in that, The angle adjustment mechanism includes a hand-tightening bolt, which is connected to the coil assembly and the lower end of the telescopic frame.

9. The magnetic field control device for laser welding of dissimilar materials according to claim 6, characterized in that, The angle adjustment mechanism includes a servo motor, the housing of which is connected to the lower end of the telescopic frame, and the shaft of which is connected to the coil assembly.

10. The magnetic field control device for laser welding of dissimilar materials according to claim 9, characterized in that, The coil assembly includes: An iron core, which is arranged along the axial direction of the coil assembly and connected to the angle adjustment mechanism; A coil, which is sleeved on the outer periphery of the iron core.

11. The magnetic field control device for laser welding of dissimilar materials according to claim 10, characterized in that, The protective gas system includes: High-purity argon gas source; The main nozzle has an annular flow channel formed between the coil and the iron core, and the end of the annular flow channel away from the angle adjustment mechanism is connected to the main nozzle. A gas pipeline is connected to the high-purity argon gas source and the end of the annular flow channel near the angle adjustment mechanism.

12. The magnetic field control device for laser welding of dissimilar materials according to claim 11, characterized in that, The protective gas system also includes: A nozzle on the back of the weld is located at the bottom of the workbench and is connected to the gas pipeline.

13. A magnetic field control method for laser welding of dissimilar materials, said magnetic field control method being based on the magnetic field control device for laser welding of dissimilar materials according to any one of claims 1 to 12, characterized in that, include: The initial current parameters were determined based on the physicochemical properties of the two different welding materials. Based on the initial current parameters, the power controller supplies current to the coil assembly; The protective gas system is controlled to operate, thereby cooling the coil and continuously supplying high-purity argon gas to the molten pool to be welded. The laser welding head outputs a laser beam, and the power controller controls the current method, current magnitude, and current frequency of the coil assembly according to the welding requirements, thereby changing the type of magnetic field generated by the coil assembly in the molten pool.

14. The magnetic field control method for laser welding of dissimilar materials according to claim 13, characterized in that, The step of controlling the current, current magnitude, and current frequency of the coil assembly according to welding requirements via the power controller, thereby changing the type of magnetic field generated by the coil assembly in the molten pool, includes: When it is determined that a transverse magnetic field needs to be generated, the current magnitudes of the first, second, third, and fourth coils are all controlled to be the same. The current directions of the first and second coils are the same, and the current directions of the third and fourth coils are the same but opposite to the current direction of the first coil. A transverse magnetic field perpendicular to the plane containing the laser beam and the welding direction is generated at the center of the molten pool. The direction of the magnetic field is +x or -x. When it is determined that a longitudinal magnetic field needs to be generated, the current magnitudes of the first coil, the second coil, the third coil, and the fourth coil are all controlled to be the same. The current directions of the first coil and the fourth coil are the same, and the current directions of the second coil and the third coil are the same but opposite to the current direction of the first coil. A longitudinal magnetic field parallel to the welding direction is generated at the center of the molten pool, and the direction of the magnetic field is +y or -y. When it is determined that an axial magnetic field needs to be generated, the magnitude and direction of the current in the first coil, the second coil, the third coil, and the fourth coil are all controlled to be the same, so as to generate an axial magnetic field parallel to the laser beam axis at the center of the molten pool, with the direction of the magnetic field being +z or -z. When it is determined that an asymmetric magnetic field needs to be generated, the current magnitude and direction of the first coil and the second coil are controlled to be the same, the current magnitude of the third coil and the fourth coil is the same, but different from the current magnitude of the first coil; the current direction of the third coil and the fourth coil is the same, but opposite to the current direction of the first coil; thus generating an asymmetric magnetic field inside the molten pool with a large magnetic field strength on one side and a small magnetic field strength on the other side. Alternatively, the current directions of the first coil and the second coil are controlled to be the same, and the current magnitudes of the first coil and the second coil are different; the current magnitudes of the second coil, the third coil, and the fourth coil are controlled to be the same, and the current directions of the third coil and the fourth coil are the same, but opposite to the current direction of the first coil; thus generating an asymmetric magnetic field inside the molten pool with a large single-angle magnetic field strength and small strengths of the other magnetic fields; When it is determined that a steady magnetic field needs to be generated, the current frequencies of the first coil, the second coil, the third coil, and the fourth coil in the above steps are all controlled to be 0. When it is determined that an alternating magnetic field needs to be generated, the current frequencies of the first coil, the second coil, the third coil, and the fourth coil in the above steps are controlled to be predetermined values, wherein the predetermined values ​​are greater than or equal to zero, and the current frequency of at least one coil is greater than zero. When it is determined that a rotating magnetic field needs to be generated, the current changes of the first coil, the second coil, the third coil, and the fourth coil are controlled to make the direction of the magnetic field at the center of the molten pool continuously change.

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