Laser welding device for welding steel pipes

Abstract

The invention provides a laser welding device for welding steel pipes, which comprises a welding platform and a transfer platform which are connected with each other, a driving assembly is arranged on the welding platform, the driving assembly is operatively connected with a laser welding head, and the laser welding head is positioned above the transfer platform; the transferring platform is provided with a transferring device used for transferring a steel pipe to the position below the laser welding head, the upstream of the transferring direction and the overlapping area of the laser welding head form a welding area, and a plurality of sets of supporting units distributed in the axial direction of the steel pipe are arranged on the downstream of the transferring direction. The supporting unit comprises three supporting modules which are evenly distributed in the circumferential direction of the steel pipe at 120 degrees, and each supporting module comprises a shell structure, a coil assembly, a magnetorheological fluid actuator and a contact head assembly which are sequentially arranged from outside to inside in the radial direction of the steel pipe.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel pipe processing, and in particular to a laser welding device for welding steel pipes. Background Art

[0002] The application of laser welding devices in welding stainless steel pipes is mainly reflected in its high efficiency, precision and high quality welding characteristics. The laser welding device has the characteristics of high energy density and can produce high energy beam density, which enables laser welding to form keyholes during the welding process, thereby obtaining narrow and deep welds.

[0003] The working principle of the laser welding device is roughly as follows: the laser generates a high-energy continuous / pulsed laser beam with a power range of 1 to 10kW. The laser is transmitted to the focusing head through an optical fiber or a reflector group. The focusing head converges the beam to a micron-level spot, forming an extremely high energy density, and then instantly melts the metal at the joint of the steel pipe. The steel pipe is clamped by a rotating roller driven by a servo motor and rotates at a linear speed of 0.5 to 5m / min. The laser head moves axially at a synchronous speed to form a spiral weld. During the welding process, an inert gas is ejected from the coaxial nozzle to prevent oxidation of the molten pool.

[0004] However, the high temperature generated by such a high energy density will cause thermal deformation for thin-walled tubes. For example, for thin-walled tubes with a thickness of less than 2 mm, in the absence of support compensation, the roundness loss will reach 0.5 mm, thus affecting the welding effect. Summary of the invention

[0005] The present invention aims to solve the above-mentioned technical problems and provides a laser welding device for welding steel pipes.

[0006] A technical solution of the present invention is a laser welding device for welding steel pipes, comprising a connected welding platform and a transfer platform, wherein a driving assembly is provided on the welding platform, wherein the driving assembly is operatively connected to a laser welding head, and wherein the laser welding head is located above the transfer platform;

[0007] The transfer platform is provided with a transfer device for transferring the steel pipe to the bottom of the laser welding head, the upstream of the transfer direction and the overlapping area of ​​the laser welding head form a welding area, and the downstream of the transfer direction is provided with a plurality of groups of support units distributed along the axial direction of the steel pipe, the support unit includes 3 support modules evenly distributed at 120° along the circumference of the steel pipe, and the support module includes a shell structure, a coil assembly, a magnetorheological fluid actuator, and a contact head assembly sequentially arranged from the outside to the inside along a radial direction of the steel pipe;

[0008] The coil assembly comprises a magnetic conductive ring, a plurality of annular grooves are formed on the magnetic conductive ring, and an electromagnetic coil is embedded in each of the annular grooves. The electromagnetic coil fills the annular grooves in a densely wound manner, and a plurality of the electromagnetic coils are connected in series to form a closed loop, and the current directions of adjacent electromagnetic coils are consistent, so that the magnetic field forms a continuous annular magnetic field inside the magnetic conductive ring;

[0009] The magnetorheological fluid actuator comprises a plunger cylinder, the front end of the plunger cylinder is connected to a contact head assembly through a bellows seal, the contact head assembly comprises a hemispherical end and an end seat, the hemispherical end is used to contact the surface of a steel pipe, the end seat is connected to the bellows, the end seat and the plunger rod of the plunger cylinder are connected through a disc spring group, so that the hemispherical end forms elastic displacement compensation, the cavity of the plunger cylinder is filled with a mixture of carbonyl iron powder and silicone oil, and a coupling air gap is provided between the magnetic ring and the plunger cylinder;

[0010] The transfer platform is also provided with a plurality of infrared thermometers respectively located at each of the support units. When the infrared thermometer detects a temperature change of the steel pipe in a certain area, the current of the electromagnetic coil of the support module changes accordingly.

[0011] As an embodiment, the support unit also includes a triangular frame arranged on the transfer platform, each side of the triangular frame is provided with a linear slide rail along the radial direction of the steel pipe, the linear slide rail is provided with a lockable positioning slider, and the support module is fixed on the positioning slider.

[0012] As an implementation mode, the particle size of the carbonyl iron powder is 5 μm, the volume fraction is 40%, the viscosity of the silicone oil is 0.1 Pa·s, and the filling rate of the mixed liquid formed by the carbonyl iron powder and the silicone oil in the cavity of the plunger cylinder is 95%.

[0013] As an implementation mode, the hemispherical end is made of reaction-sintered silicon carbide ceramic and a wear-resistant layer of aluminum nitride is sprayed on the surface.

[0014] As an embodiment, the plunger rod includes an inner rod and an outer rod, the inner rod and the outer rod are connected by a graphite insulation plate, the front end of the plunger cylinder is provided with an end plate with a central hole, the bellows is connected to the end plate, and the central hole is for the inner rod, the graphite insulation plate, and the outer rod to pass through.

[0015] As an implementation manner, a front end of the plunger cylinder is provided with an annular groove, and the annular groove is used for the end plate to be clamped.

[0016] As an embodiment, the driving assembly includes a base, a column is provided on the base, a slide is provided on the column along the vertical direction, an electric actuator is provided at the top of the slide, a lifting plate is provided at the bottom of the slide and extends toward the side where the transfer platform is located, and the laser welding head is fixed on the lifting plate.

[0017] As an embodiment, the welding platform includes a first bottom plate, the base is arranged on the first bottom plate, the transfer platform includes a second bottom plate, the transfer device and the support unit are arranged on the second bottom plate, and the first bottom plate and the second bottom plate are connected and fixed by a connecting rod.

[0018] As an implementation manner, the number of the supporting units is set to 3.

[0019] As an implementation manner, the number of the annular groove and the number of the electromagnetic coils are both 12.

[0020] Compared with the prior art, the present invention has the beneficial effect that the laser welding device for welding steel pipes is used to deal with the thermal deformation problem of steel pipes during laser welding. The laser welding device for welding steel pipes has a plurality of support units distributed along the axial direction of the steel pipe, thereby forming a multi-segment support structure, and each support unit can independently respond to local thermal deformation. Each support unit includes three support modules evenly distributed at 120°, surrounding the outer wall of the steel pipe to form a full circumferential dynamic constraint. Among them, each support module is composed of a shell structure, a coil assembly, a magnetorheological fluid actuator, and a contact head assembly. The axis of the magnetic ring points to the radial direction of the steel pipe (perpendicular to the surface of the steel pipe), and the direction of the magnetic field is along the radial direction of the steel pipe (from outside to inside or from inside to outside), directly acting on the magnetorheological fluid cavity. Specifically, when the direction of the magnetic field is along the radial direction of the steel pipe, the iron powder particles in the magnetorheological fluid will form a chain structure along the direction of the magnetic field (radial direction), significantly increasing the viscosity of the liquid. At this time, the radial movement resistance (support force) generated by the plunger of the plunger cylinder under the thermal deformation pressure of the steel pipe is consistent with the direction of the magnetic field, which can maximize the suppression of the radial deformation of the steel pipe. A small air gap is retained between the magnetic ring and the magnetorheological fluid cavity. The magnetic field lines start from the magnetic ring, pass through the air gap into the cavity, and then return to the magnetic ring through the plunger to form a closed magnetic circuit. The direction of the magnetic field is consistent with the direction of thermal deformation of the steel pipe (radial expansion / contraction), and the deformation is effectively resisted by adjusting the viscosity of the magnetorheological fluid. For each local thermal deformation, the temperature change of the area is detected by the infrared thermometer. When the detected temperature rises, the coil current of the corresponding support module is increased, and the enhanced magnetic field causes the iron powder particles in the magnetorheological fluid to form a chain structure, the viscosity increases, and the resistance of the plunger cylinder to the plunger movement is changed, thereby affecting the support stiffness of the support module and suppressing the warping of the steel pipe. The laser welding device for welding steel pipes realizes real-time dynamic suppression of welding thermal deformation based on the electromagnetic-rheological-mechanical multi-field coupling method, and can be used in high-precision thin-walled pipe welding scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of a laser welding device for welding steel pipes provided in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a support module provided in an embodiment of the present invention;

[0023] Figure 3 A cross-sectional view of a housing structure provided for an embodiment of the present invention;

[0024] Figure 4 A schematic structural diagram of a linear slide rail and a positioning slider provided in an embodiment of the present invention.

[0025] In the figure: 1. welding platform; 2. transfer platform; 3. drive assembly; 4. laser welding head; 5. steel pipe; 6. transfer device; 7. welding area; 8. support unit; 9. support module; 10. shell structure; 11. coil assembly; 12. magnetorheological fluid actuator; 13. contact head assembly; 14. magnetic ring; 15. annular groove; 16. electromagnetic coil; 17. plunger cylinder; 18. bellows; 19. hemispherical End; 20. End seat; 21. Disc spring assembly; 22. Coupling air gap; 23. Infrared thermometer; 24. Triangular frame; 25. Linear guide rail; 26. Positioning slider; 27. Inner rod; 28. Outer rod; 29. ​​Graphite insulation board; 30. Middle hole; 31. End plate; 32. Annular groove; 33. Base; 34. Column; 35. Slide; 36. Electric actuator; 37. Lifting plate; 38. Connecting rod. DETAILED DESCRIPTION

[0026] The above and other embodiments and advantages of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments.

[0027] In one embodiment, if Figures 1 to 3 shown.

[0028] The laser welding device for welding steel pipes provided in this embodiment comprises a connected welding platform 1 and a transfer platform 2, wherein a driving assembly 3 is provided on the welding platform 1, and the driving assembly 3 is operatively connected to a laser welding head 4, and the laser welding head 4 is located above the transfer platform 2; a transfer device 6 for transferring the steel pipe 5 to the bottom of the laser welding head 4 is provided on the transfer platform 2, and a welding area 7 is formed by the overlapping area of ​​the upstream of the transfer direction and the laser welding head 4, and a plurality of groups of support units 8 distributed along the axial direction of the steel pipe 5 are provided downstream of the transfer direction, and the support unit 8 comprises three support modules 9 uniformly distributed at 120° along the circumference of the steel pipe 5, and the support module 9 comprises a shell structure 10, a coil assembly 11, a magnetorheological fluid actuator 12, and a contact head assembly 13 sequentially arranged from the outside to the inside along a radial direction of the steel pipe 5; the coil assembly 11 comprises a magnetic ring 14, and a plurality of annular grooves 15 are provided on the magnetic ring 14, and an electromagnetic coil 16 is embedded in each annular groove 15, and the electromagnetic coil 16 is wound in a dense manner. The annular groove 15 is filled in a manner, and a plurality of electromagnetic coils 16 are connected in series to form a closed loop. The current directions of adjacent electromagnetic coils 16 are consistent, so that the magnetic field forms a continuous annular magnetic field inside the magnetic conductive ring 14; the magnetorheological fluid actuator 12 includes a plunger cylinder 17, and the front end of the plunger cylinder 17 is sealed and connected to the contact head assembly 13 through a bellows 18. The contact head assembly 13 includes a hemispherical end 19 and an end seat 20. The hemispherical end 19 is used to contact the surface of the steel pipe 5, and the end seat 20 is connected to the bellows 18. The end seat 20 and the plunger rod of the plunger cylinder 17 are connected by a disc spring group 21 to enable the hemispherical end 19 to form elastic displacement compensation. The cavity of the plunger cylinder 17 is filled with a mixture of carbonyl iron powder and silicone oil, and a coupling air gap 22 is provided between the magnetic ring 14 and the plunger cylinder 17; the transfer platform 2 is also provided with a plurality of infrared thermometers 23 located at each support unit 8 respectively. When the infrared thermometer 23 detects a temperature change of the steel pipe 5 in a certain area, the current of the electromagnetic coil 16 of the support module 9 changes accordingly.

[0029] In this embodiment, the laser welding device for welding steel pipes is used to deal with the thermal deformation problem of the steel pipe 5 during the laser welding process. The laser welding device for welding steel pipes 5 has a plurality of groups of support units 8 distributed along the axial direction of the steel pipe 5, thereby forming a multi-segment support structure, and each support unit 8 can independently respond to local thermal deformation. Each support unit 8 includes three support modules 9 evenly distributed at 120°, surrounding the outer wall of the steel pipe 5, forming a full circumferential dynamic constraint.

[0030] The circumferential dynamic constraint is embodied as follows: if the side wall of the steel pipe 5 corresponding to one of the support modules 9 shows a tendency to warp outward, the support effect of the support module 9 with variable support stiffness can effectively suppress the outward warping of the steel pipe 5. If the side wall of the steel pipe 5 corresponding to one of the support modules 9 shows a tendency to warp inward, the inward warping tendency at this position means the outward warping tendency at other positions, then the support effect of the support modules 9 at the other two positions with variable support stiffness can effectively suppress the outward warping at other positions of the steel pipe 5, and indirectly suppress the inward warping at this position of the steel pipe 5, which is why the support unit 8 includes three support modules 9 that evenly surround the outer wall of the steel pipe 5 at 120°.

[0031] The support module 9 can provide a support with variable support stiffness because each support module 9 is composed of a shell structure 10, a coil assembly 11, a magnetorheological fluid actuator 12, and a contact head assembly 13. The axis of the magnetic ring 14 points to the radial direction of the steel pipe 5 (perpendicular to the surface of the steel pipe 5), and the direction of the magnetic field is along the radial direction of the steel pipe 5 (from outside to inside or from inside to outside), directly acting on the magnetorheological fluid cavity. Specifically, when the direction of the magnetic field is along the radial direction of the steel pipe 5, the iron powder particles in the magnetorheological fluid will form a chain structure along the direction of the magnetic field (radial), significantly increasing the viscosity of the liquid. At this time, the radial motion resistance (support force) generated by the plunger of the plunger cylinder 17 under the thermal deformation pressure of the steel pipe 5 is consistent with the direction of the magnetic field, which can maximize the suppression of the radial deformation of the steel pipe 5. A small air gap is retained between the magnetic ring 14 and the magnetorheological fluid cavity. The magnetic field lines start from the magnetic ring 14, pass through the air gap into the cavity, and then return to the magnetic ring 14 through the plunger to form a closed magnetic circuit. The direction of the magnetic field is made consistent with the thermal deformation direction (radial expansion / contraction) of the steel pipe 5, and deformation is effectively resisted by adjusting the viscosity of the magnetorheological fluid.

[0032] For each local thermal deformation, the temperature change of the detection area is detected by the infrared thermometer 23. For example, when the detection temperature rises, the coil current of the corresponding support module 9 is increased, and the enhanced magnetic field causes the iron powder particles in the magnetorheological fluid to form a chain structure, the viscosity increases, and the resistance of the plunger cylinder 17 to the plunger movement is changed, thereby affecting the support stiffness of the support module 9 and suppressing the warping of the steel pipe 5. The laser welding device for welding the steel pipe 5 realizes real-time dynamic suppression of welding thermal deformation based on the electromagnetic-rheological-mechanical multi-field coupling method, and can be used in high-precision thin-walled pipe welding scenarios.

[0033] In one embodiment, if Figure 1 shown.

[0034] The laser welding device for welding steel pipes provided in this embodiment, its support unit 8 also includes a triangular frame 24 arranged on the transfer platform 2, each side of the triangular frame 24 is provided with a linear slide rail 25 along the radial direction of the steel pipe 5, the linear slide rail 25 is provided with a lockable positioning slider 26, and the support module 9 is fixed on the positioning slider 26.

[0035] In this embodiment, the support unit 8 is connected to the transfer platform 2 serving as the main body of the device through a high-strength aluminum alloy bracket, namely a triangular frame 24. The triangular frame 24 is equipped with a linear slide rail 25 and a locking bolt, allowing ±10mm radial position adjustment to accommodate different pipe diameters (Φ50-Φ300mm).

[0036] In one embodiment, the laser welding device for welding steel pipes has a carbonyl iron powder with a particle size of 5 μm and a volume fraction of 40%, a silicone oil with a viscosity of 0.1 Pa·s, and a filling rate of a mixed liquid formed by the carbonyl iron powder and the silicone oil in the cavity of the plunger cylinder 17 of 95%.

[0037] In this embodiment, magnetorheological fluid actuator 12 is used to realize magnetic-mechanical coupling, and the mixture formed by carbonyl iron powder and silicone oil can change its viscosity in the change of magnetic field due to the characteristics of the materials. For example, when the infrared thermometer 23 detects that the temperature of the steel pipe 5 in a certain area increases by ΔT, the control system increases the coil current (I=0-5A) of the corresponding support module 9. The enhanced magnetic field causes the iron powder particles in the magnetorheological fluid to form a chain structure, and the viscosity increases from 10Pa·s to 100Pa·s. The movement resistance of the plunger has a specific relationship with the viscosity. Therefore, the movement resistance of the plunger changes with the viscosity, and finally the support stiffness changes dynamically within a range.

[0038] In one embodiment, the hemispherical end 19 of the laser welding device for welding steel pipes is made of reaction-sintered silicon carbide ceramics and has an aluminum nitride wear-resistant layer sprayed on the surface.

[0039] In this embodiment, the hemispherical end 19 adopts a spherical contact surface to reduce friction, and adopts a ceramic material to have sufficient hardness and high temperature resistance.

[0040] In one embodiment, if Figure 2 shown.

[0041] The laser welding device for welding steel pipes provided in this embodiment has a plunger rod including an inner rod 27 and an outer rod 28, and the inner rod 27 and the outer rod 28 are connected by a graphite insulation plate 29. The front end of the plunger cylinder 17 is provided with an end plate 31 with a center hole 30, and the bellows 18 is connected to the end plate 31. The center hole 30 is for the inner rod 27, the graphite insulation plate 29, and the outer rod 28 to pass through.

[0042] In this embodiment, the plunger rod is divided into two sections, an inner rod 27 and an outer rod 28, which are connected in the middle by a graphite insulation plate 29, so that the radiant heat of the steel pipe 5 can be blocked from being transferred to the magnetorheological fluid chamber.

[0043] In one embodiment, if Figure 2 shown.

[0044] In the laser welding device for welding steel pipes provided in this embodiment, the front end of the plunger cylinder 17 is provided with an annular groove 32 for the end plate 31 to be clamped.

[0045] In this embodiment, a connection method between the end plate 31 and the plunger cylinder 17 is provided.

[0046] In one embodiment, if Figure 2 shown.

[0047] The laser welding device for welding steel pipes provided in this embodiment has a driving assembly 3 including a base 33, a column 34 is provided on the base 33, a slide 35 arranged in a vertical direction is provided on the column 34, an electric actuator 36 is provided at the top of the slide 35, a lifting plate 37 extending toward the side where the transfer platform 2 is located is provided at the bottom of the slide 35, and the laser welding head 4 is fixed on the lifting plate 37. In addition, the welding platform 1 and the transfer platform 2 are connected and fixed by a connecting rod 38.

[0048] In the present embodiment, an implementable configuration of a drive assembly 3 is provided, wherein the drive assembly 3 is used to control the position of a laser welding head 4 .

[0049] The above specific implementation methods further describe the invention purpose, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser welding device for welding steel pipes, characterized in that: The invention comprises a welding platform (1) and a transfer platform (2) connected to each other, wherein a driving assembly (3) is provided on the welding platform (1), and the driving assembly (3) is operatively connected to a laser welding head (4), and the laser welding head (4) is located above the transfer platform (2); The transfer platform (2) is provided with a transfer device (6) for transferring the steel pipe (5) to the bottom of the laser welding head (4); the upstream of the transfer direction and the overlapping area of ​​the laser welding head (4) form a welding area (7); the downstream of the transfer direction is provided with a plurality of groups of support units (8) distributed along the axial direction of the steel pipe (5); the support unit (8) includes three support modules (9) evenly distributed at 120° along the circumference of the steel pipe (5); the support module (9) includes a shell structure (10), a coil assembly (11), a magnetorheological fluid actuator (12), and a contact head assembly (13) arranged in sequence from the outside to the inside along a radial direction of the steel pipe (5); The coil assembly (11) comprises a magnetic conductive ring (14), a plurality of annular grooves (15) are formed on the magnetic conductive ring (14), an electromagnetic coil (16) is embedded in each of the annular grooves (15), the electromagnetic coil (16) fills the annular groove (15) in a densely wound manner, a plurality of the electromagnetic coils (16) are connected in series to form a closed loop, and the current directions of adjacent electromagnetic coils (16) are consistent, so that the magnetic field forms a continuous annular magnetic field inside the magnetic conductive ring (14); The magnetorheological fluid actuator (12) comprises a plunger cylinder (17), the front end of the plunger cylinder (17) is sealed and connected to a contact head assembly (13) via a bellows (18), the contact head assembly (13) comprises a hemispherical end head (19) and an end head seat (20), the hemispherical end head (19) is used to contact the surface of a steel pipe (5), the end head seat (20) is connected to the bellows (18), the end head seat (20) and the plunger rod of the plunger cylinder (17) are connected via a disc spring group (21) so that the hemispherical end head (19) forms elastic displacement compensation, the cavity of the plunger cylinder (17) is filled with a mixture of carbonyl iron powder and silicone oil, and a coupling air gap (22) is provided between the magnetic conductive ring (14) and the plunger cylinder (17); The transfer platform (2) is also provided with a plurality of infrared thermometers (23) respectively located at each of the support units (8). When the infrared thermometer (23) detects a temperature change of the steel pipe (5) in a certain area, the current of the electromagnetic coil (16) of the support module (9) changes accordingly.

2. The laser welding device for welding steel pipes according to claim 1, characterized in that: The support unit (8) further comprises a triangular frame (24) arranged on the transfer platform (2), each side of the triangular frame (24) being provided with a linear slide rail (25) along the radial direction of the steel pipe (5), the linear slide rail (25) being provided with a lockable positioning slide block (26), and the support module (9) being fixed on the positioning slide block (26).

3. The laser welding device for welding steel pipes according to claim 1, characterized in that: The particle size of the carbonyl iron powder is 5 μm, the volume fraction is 40%, the viscosity of the silicone oil is 0.1 Pa·s, and the filling rate of the mixed liquid formed by the carbonyl iron powder and the silicone oil in the cavity of the plunger cylinder (17) is 95%.

4. The laser welding device for welding steel pipes according to claim 1, characterized in that: The hemispherical end head (19) is made of reaction-sintered silicon carbide ceramics and has an aluminum nitride wear-resistant layer sprayed on its surface.

5. The laser welding device for welding steel pipes according to claim 1, characterized in that: The plunger rod comprises an inner rod (27) and an outer rod (28), wherein the inner rod (27) and the outer rod (28) are connected via a graphite heat insulation plate (29), and the front end of the plunger cylinder (17) is provided with an end plate (31) with a center hole (30), and the bellows (18) is connected to the end plate (31), and the center hole (30) is for the inner rod (27), the graphite heat insulation plate (29), and the outer rod (28) to pass through.

6. The laser welding device for welding steel pipes according to claim 5, characterized in that: The front end of the plunger cylinder (17) is provided with an annular clamping groove (32), and the annular clamping groove (32) is clamped by the end plate (31).

7. The laser welding device for welding steel pipes according to claim 1, characterized in that: The driving assembly (3) comprises a base (33), a column (34) is provided on the base (33), a slide (35) arranged along the vertical direction is provided on the column (34), an electric actuator (36) is provided at the top of the slide (35), a lifting plate (37) extending toward the side where the transfer platform (2) is located is provided at the bottom of the slide (35), and the laser welding head (4) is fixed on the lifting plate (37).

8. The laser welding device for welding steel pipes according to claim 1, characterized in that: The welding platform (1) and the transfer platform (2) are connected and fixed via a connecting rod (38).

9. The laser welding device for welding steel pipes according to claim 1, characterized in that: The number of the supporting units (8) is set to be three.

10. The laser welding device for welding steel pipes according to claim 1, characterized in that: The number of the annular groove (15) and the number of the electromagnetic coil (16) are both 12.

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