Ultrasonic-assisted laser and MIG composite welding method and device

Abstract

The invention belongs to the technical field of laser welding, and discloses an ultrasonic-assisted laser and MIG composite welding method and device. The device comprises an MIG electric arc welding gun connected with the positive electrode of a power source, and a to-be-welded workpiece connected with the negative electrode of the power source. A Y-shaped groove is formed in the upper portion of the to-be-welded workpiece. The MIG arc welding gun is located in front of the laser in the welding advancing direction of the Y-shaped groove and forms a certain angle with a workpiece to be welded, the two first ultrasonic generators which are arranged in an axial symmetry mode are connected through the connecting base, each first ultrasonic generator is connected with one ultrasonic peening needle, and the two ultrasonic peening needles are transversely distributed on the two sides of the arc welding gun in an axial symmetry mode. The second ultrasonic generator is located under a molten pool formed by welding of the Y-shaped groove. By means of the ultrasonic acoustic streaming effect, cavitation effect, mechanical vibration and heat effect, welding air holes are eliminated, the workpiece welding residual stress is reduced, grains are refined, and the performance of a welding joint is improved.

Description

Technical Field

[0001] This invention belongs to the field of laser welding technology, and particularly relates to a method and apparatus for ultrasonic-assisted laser and MIG composite welding. Background Technology

[0002] In recent years, with the continuous development of high-end manufacturing, traditional welding methods can no longer meet people's requirements for high efficiency and high quality welding. Laser-arc hybrid welding couples two heat sources, using laser to stabilize the arc, increase penetration, and improve welding efficiency. At the same time, the arc improves the tolerance for assembly gaps, achieving a synergistic effect of "1+1>2", making it a breakthrough technology with broad application prospects. However, laser-arc hybrid welding still has the following problems: In the welding process of medium and thick plates, the end of the welding wire is prone to forming an arc with the side of the workpiece bevel, resulting in sidewall arcing, which greatly reduces the stability of the welding process, and the weld formation is poor and prone to internal defects; the molten pool flows violently, and the back of the weld joint is prone to collapse or weld beads; the weld penetration is large, and the gas inside the molten pool is not easy to escape, which easily produces porosity; the weld grains are mostly dendritic, and the joint performance needs to be improved.

[0003] Ultrasonic assistance provides a feasible solution to the above problems, enabling laser-arc hybrid welding to exhibit superior performance. For the issue of sidewall arcing that may occur during medium-thick plate welding, transverse ultrasound can be introduced. Transverse ultrasound can confine the plasma, limiting the arc to the bottom of the weld joint bevel between the weld wire and the weld joint. This not only prevents sidewall arcing but also concentrates the arc heat, which is beneficial for increasing penetration depth and ensuring the welding quality of medium-thick plates. Simultaneously using an ultrasonic micro-forging device at the bottom of the workpiece and the welding torch allows for high-frequency mechanical vibration acting on the molten metal pool. Utilizing acoustic flow, cavitation, mechanical vibration, and thermal effects, the molten pool is stirred, releasing bubbles, promoting temperature and composition homogenization, removing residual stress in the workpiece, refining grains, and improving weld joint performance. At the same time, the ultrasonic micro-forging device can make the back weld surface smoother, and its support for the bottom of the workpiece effectively prevents collapse and weld beads on the back side, significantly improving the forming quality of single-sided welding with double-sided forming of medium-thick plates. By introducing an external energy field of ultrasound into laser-arc hybrid welding, it is possible to achieve comprehensive and precise control over the welding process from macroscopic formation to microscopic structure.

[0004] Based on this, an invention patent discloses an integrated device for laser-arc hybrid welding and ultrasonic stress relief (publication number CN112453711A, publication date: 20210309). This device connects the welding torch and the ultrasonic impact head to the weld via a base, aiming to remove residual stress from the weld. However, this solution also has certain drawbacks. Specifically, the ultrasonic impact head has a certain horizontal distance from the molten pool, which reduces the ultrasonic effect. Furthermore, this solution does not consider potential issues such as weld collapse and weld beads on the back side of the weld, or arc initiation on the arc sidewall. These problems can all lead to suboptimal welding quality.

[0005] Currently, ultrasonic-assisted laser-arc hybrid welding is limited to the stirring of the molten pool by ultrasound, achieving effects such as bubble release and grain refinement. It does not consider the control of the welding arc by ultrasound, and ultrasonic micro-forging methods have not yet been introduced into the field of laser-arc hybrid welding. In beveling welding of medium and thick plates, the welding arc may not ignite normally between the bottom of the weld joint bevel and the tip of the welding wire, but rather ignite incorrectly and uncontrollably from the base metal on the side of the bevel, resulting in sidewall arcing. Sidewall arcing not only leads to energy loss and reduced welding efficiency, but also damages the electrode, affects welding quality, and creates safety hazards. Currently, there are few solutions to this problem, and no solution using ultrasound to assist welding has yet been developed.

[0006] Meanwhile, when welding medium and thick plates, the weld penetration is large, making it difficult for gases inside the molten pool to escape, leading to porosity in the weld. The weld grains are mostly dendritic, easily becoming channels for crack propagation, resulting in high crystal brittleness and susceptibility to cracking at the weld. The vigorous flow of the molten pool also causes collapse or weld beads on the back side of the weld joint. These problems all affect welding quality and reduce weld strength. In current ultrasonic-assisted laser-arc hybrid welding methods, the ultrasonic impact head is mostly at a certain distance from the molten pool. This may not only reduce the ultrasonic effect, resulting in unsatisfactory results, but also neglects the potential collapse and weld beads on the back side of the weld during single-sided welding with double-sided forming, affecting the workpiece welding quality and forming effect. Summary of the Invention

[0007] To overcome the problems existing in related technologies, the present invention discloses an ultrasonic-assisted laser and MIG composite welding method and apparatus.

[0008] The technical solution is as follows: an ultrasonic-assisted laser and MIG arc hybrid welding device, the device includes a MIG arc welding gun connected to the positive terminal of the power supply, a workpiece to be welded connected to the negative terminal of the power supply, and a Y-shaped bevel is opened on the upper part of the workpiece to be welded. The MIG arc welding torch is positioned in front of the laser in the welding direction of the Y-groove and at a certain angle to the workpiece to be welded. Two first ultrasonic generators are connected by a connecting base, and each first ultrasonic generator is connected to an ultrasonic impact needle. The two ultrasonic impact needles are symmetrically distributed laterally on both sides of the arc welding torch. The second ultrasonic generator is located directly below the molten pool formed by the Y-groove welding.

[0009] The roller connected to the second ultrasonic generator contacts the bottom of the workpiece to be welded directly and moves along the welding direction.

[0010] The first ultrasonic generator has an ultrasonic frequency of 20-35kHz and a power of 600-1200W. The second ultrasonic generator has an ultrasonic frequency of 20-50kHz and a power of 600-1200W.

[0011] The bevel angle on one side of a Y-shaped bevel is 30°-45°.

[0012] Another object of the present invention is to provide a method for ultrasonic-assisted laser and MIG arc hybrid welding, comprising: S1, turn on the first ultrasonic generator with axial symmetry and transverse distribution, and transmit the vibration to the tip of the welding wire at the head of the MIG arc welding gun through the ultrasonic impact needle; S2, turn on the second ultrasonic generator, and the roller connected to the second ultrasonic generator contacts the bottom of the workpiece to be welded. Ultrasonic micro-forging is achieved on the bottom of the workpiece to be welded through the high-frequency vibration of the roller. S3: Simultaneously turn on the power to the MIG arc welding gun and laser to begin welding.

[0013] Step S3, welding includes: When the arc of the MIG arc welding torch is ignited, the first ultrasonic generator, which is symmetrically distributed laterally, applies high-frequency vibration to the ultrasonic impact needle. The arc heat source and the laser spot are concentrated at the bottom of the Y-shaped groove of the workpiece to be welded, and welding is performed. During the welding process, the welding wire melts and drips down, forming a molten pool under the action of high heat. The second ultrasonic generator at the bottom stirs the molten pool through ultrasonic vibration and the resulting acoustic flow and cavitation effects.

[0014] In step S3, during welding, the laser power used is 3-9kW, the arc voltage is 20-30V, and the welding speed is 0.3-1.5m / min.

[0015] Application of the ultrasonic-assisted laser and MIG arc hybrid welding method in medium and thick plate welding.

[0016] The ultrasonic-assisted laser and MIG arc hybrid welding method is mounted on a computer terminal controller and executed.

[0017] Combining all the above technical solutions, the beneficial effects of this invention are as follows: First, this invention proposes an ultrasonic-assisted laser and MIG hybrid welding method. This method combines laser and MIG arc welding to weld joints, applying axisymmetric transverse ultrasound near the welding torch to constrain the welding arc, concentrate arc heat, increase penetration, prevent sidewall arcing in medium-thick plate welding, and improve welding process stability. Simultaneously, an ultrasonic micro-forging device, moving synchronously with the welding torch, is applied to the back of the weld joint to prevent molten pool collapse and back-side weld bead formation, and to transfer ultrasonic energy to the molten pool. Utilizing the acoustic flow effect, cavitation effect, mechanical vibration, and thermal effect of ultrasound, it eliminates weld porosity, reduces residual stress in the workpiece, refines grains, and improves weld joint performance. This invention solves the problems of poor weld formation quality, low weld strength, and easy arcing on the sidewalls of beveled welds in medium-thick plate welding.

[0018] Secondly, this invention can guide the relevant production development of enterprises, significantly improve the quality and efficiency of medium and heavy plate welding, reduce the welding defect rate, thereby reducing rework and material waste, and saving enterprises a lot of costs. At the same time, this technical solution has a wide range of applications, not only applicable to the welding of various medium and heavy plates, but also extending to other fields requiring high-precision, high-quality welding, opening up new market space for enterprises. Furthermore, with the continuous development of high-end manufacturing, the requirements for welding technology will continue to increase, and the technical solution of this invention has both foresight and sustainability.

[0019] Third, most existing ultrasonic-assisted laser-arc hybrid welding technologies focus only on the stirring effect of ultrasound on the molten pool to achieve effects such as releasing bubbles and refining grains, while neglecting the control of the welding arc by ultrasound and failing to introduce ultrasonic micro-forging methods into the field of medium-thick plate laser-arc hybrid welding. This invention, through a unique device design and innovative welding method, comprehensively utilizes an axisymmetric transverse ultrasonic confined arc and ultrasonic micro-forging equipment acting on the bottom of the molten pool, successfully solving the aforementioned series of problems. It provides a completely new approach and direction for the technological development of this field, demonstrating significant technological innovation and leading-edge technology.

[0020] Fourth, in the welding process of medium and heavy plates, problems such as sidewall arc initiation, molten pool collapse, weld bead formation, inclusion of porosity, and poor weld grain properties have always been key technical challenges restricting the improvement of welding quality. These problems not only lead to low welding efficiency but also increase the welding defect rate, raise production costs, and may even cause safety hazards. Although the industry has conducted long-term research and exploration on this issue, a comprehensive and effective solution has yet to be found. This invention successfully solves these problems by introducing an axisymmetric transverse ultrasonic confined arc and ultrasonic micro-forging equipment acting on the bottom of the molten pool, achieving stable control of the welding process and a significant improvement in welding quality. This technological breakthrough not only satisfies people's desire for high-quality welding but also provides new possibilities for the technological development of the medium and heavy plate welding field. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure; Figure 1 This is a schematic diagram of the ultrasonic-assisted laser and MIG composite welding device provided in an embodiment of the present invention; Figure 2 This is a cross-sectional schematic diagram of the ultrasonic-assisted laser and MIG composite welding device provided in an embodiment of the present invention; Figure 3 This is a diagram showing the distribution of components along the welding direction of the ultrasonic-assisted laser and MIG composite welding device provided in an embodiment of the present invention. Figure 4 This is a flowchart of the ultrasonic-assisted laser and MIG arc hybrid welding method provided in the embodiments of the present invention; In the diagram: 1. Laser; 2. MIG arc welding torch; 3. Welding wire; 4. Ultrasonic impact needle; 5. First ultrasonic generator; 6. Connecting base; 7. Roller; 8. Second ultrasonic generator; 9. Workpiece to be welded; 10. Y-shaped bevel. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] The innovation of this invention lies in its proposed ultrasonic-assisted laser-MIG arc hybrid welding method. This method achieves a technological breakthrough through the synergistic cooperation of two ultrasonic devices: axisymmetric transverse ultrasonic devices are configured on both sides of the MIG arc welding torch 2 to constrain the arc, suppressing sidewall arc initiation and increasing penetration depth; in conjunction with an ultrasonic micro-forging device that moves synchronously with the welding torch at the bottom of the workpiece, the molten pool is stirred to homogenize temperature and composition, relieve stress and remove bubbles, refine grains, and simultaneously support and shape the back of the weld to prevent collapse and weld beads. Through this technical solution, this invention significantly improves the quality, weld strength, and back-side smoothness of single-sided welding of medium-thick plates with double-sided forming while ensuring welding process safety, fully meeting the welding performance and forming requirements of the workpiece.

[0024] Example 1, related technical terms include: Laser-MIG hybrid welding: Laser-MIG hybrid welding organically combines laser welding and MIG welding (gas inert gas welding) processes, allowing them to work synergistically. The laser achieves deep penetration welding, while the electric arc achieves filling, forming a brand-new, highly efficient welding method with performance far exceeding the simple sum of the two.

[0025] Sidewall arc ignition: During the welding process, the welding arc is not ignited normally between the bottom of the weld joint bevel and the tip of the welding wire 3, but is mistakenly and uncontrollably ignited on the base metal on the side of the bevel. This phenomenon is especially prone to occur in the welding of medium and thick plates.

[0026] The present invention combines the laser welding gun, arc welding, axisymmetric transverse ultrasonic equipment and ultrasonic micro-forging equipment to weld the workpiece 9 to be welded under the condition of opening a Y-shaped bevel in medium and thick plates, so as to achieve single-sided welding and double-sided forming of medium and thick plates, with good welding quality and high weld strength.

[0027] This invention features axisymmetric transverse ultrasonic devices on both sides of the arc welding torch to constrain the welding arc, effectively preventing arc initiation on the sidewalls. At the same time, it concentrates heat, increases penetration, and improves the welding quality of medium and thick plates.

[0028] This invention introduces an ultrasonic micro-forging device and proposes to place it at the bottom of the workpiece 9 to be welded, move it synchronously with the welding torch, fully stir the molten pool, homogenize the temperature and composition, eliminate bubbles and residual stress, refine the grains, and at the same time support and shape the back of the weld, prevent back collapse and weld beads, improve welding quality, and meet the workpiece forming requirements.

[0029] like Figures 1-3 As shown, an ultrasonic-assisted laser and MIG arc hybrid welding device mainly includes a laser 1, a MIG arc welding gun 2, a welding wire 3, two ultrasonic impact pins 4 arranged symmetrically 4, a first ultrasonic generator 5, a connecting base 6, a roller 7, a second ultrasonic generator 8, and a workpiece to be welded 9.

[0030] Among them, the MIG arc welding gun 2 is connected to the positive terminal of the power supply, the workpiece to be welded 9 is connected to the negative terminal of the power supply, and the upper part of the workpiece to be welded 9 has a Y-shaped bevel 10.

[0031] The MIG arc welding torch 2 is positioned in front of the laser 1 in the welding travel direction of the Y-groove 10 and at a certain angle to the workpiece 9 to be welded. Two first ultrasonic generators 5 are connected by a connecting base 6, and each first ultrasonic generator 5 is connected to an ultrasonic impact needle 4. The two ultrasonic impact needles 4 are axially symmetrically distributed laterally on both sides of the arc welding torch 2. The second ultrasonic generator 8 is located directly below the molten pool formed by the welding of the Y-groove 10. The small-diameter roller 7 connected to the second ultrasonic generator 8 directly contacts the bottom of the workpiece 9 to be welded and moves along the welding travel direction at the same speed as the welding travel speed.

[0032] Example 2, as Figure 4 As shown, this embodiment of the invention provides a method for ultrasonic-assisted laser and MIG arc hybrid welding, comprising: S1. First, turn on the first ultrasonic generator 5, which is symmetrically distributed laterally, and use an ultrasonic frequency of 20-35kHz and a power of 600-1200W. The vibration is transmitted to the vicinity of the tip of the welding wire 3 at the head of the MIG arc welding gun 2 through the ultrasonic impact needle 4.

[0033] S2, turn on the second ultrasonic generator 8, use an ultrasonic frequency of 20-50kHz and a power of 600-1200W, the roller 7 connected to the second ultrasonic generator 8 directly contacts the bottom of the workpiece 9 to be welded, and ultrasonic micro-forging is achieved on the bottom of the workpiece 9 to be welded through the high-frequency vibration of the roller 7.

[0034] S3, simultaneously turn on the power supply of MIG arc welding gun 2 and laser 1 to perform welding; wherein the bevel angle of the Y-shaped groove 10 of the workpiece to be welded is 30°-45° on one side, the laser power of laser 1 is 3-9kW, the arc voltage is 20-30V, and the welding speed is 0.3-1.5m / min.

[0035] In step S3, welding includes: When the arc of the MIG arc welding torch 2 is ignited, the first ultrasonic generator 5, which is symmetrically distributed laterally, applies high-frequency vibrations to the arc plasma through the ultrasonic impact needle 4, constrains it, prevents the occurrence of arc initiation on the side wall, concentrates the arc heat, and deepens the molten pool to facilitate welding of medium and thick plates.

[0036] After the electric arc is correctly ignited, the arc heat source and the laser spot are focused on the bottom of the Y-shaped groove 10 of the workpiece 9 to be welded, and then welded.

[0037] During the welding process, the welding wire 3 melts and drips, forming a deep molten pool under the action of high heat. The second ultrasonic generator 8 at the bottom stirs the molten pool through ultrasonic vibration and the generated acoustic flow effect and cavitation effect, so as to homogenize the temperature and composition of the molten pool, release the bubbles in it, break up dendrites, refine grains, remove residual stress, ensure the strength and quality of the weld, support the back of the workpiece, prevent collapse and weld beads, smooth its surface, and improve the quality of weld formation.

[0038] It is known that the present invention can achieve single-sided welding and double-sided forming of medium-thick plates with Y-shaped groove 10, with high welding strength, good quality, no collapse or weld bead formation on the back side, and no need to repeat the processing of the back side of the workpiece.

[0039] As demonstrated by the above embodiments, this invention designs a novel ultrasonic-assisted laser-MIG arc hybrid welding method. By applying axisymmetric transverse ultrasound to both sides of the MIG (metal inert gases) arc welding torch, the arc plasma is constrained, concentrating the arc at the bottom of the weld. This not only effectively solves the problem of sidewall arc initiation but also concentrates arc heat, increases weld penetration, improves the quality of welded joints in single-sided welding of medium-thick plates with double-sided forming, and enhances safety during the welding process. Simultaneously, an ultrasonic micro-forging device is synchronously installed at the bottom of the weld with the welding torch. The high-frequency mechanical vibration directly acts on the bottom of the molten pool, not only stirring the molten pool, eliminating stress, releasing bubbles, and refining grains, but also providing support and shaping, preventing collapse and weld beads on the back side of the weld during single-sided welding with double-sided forming, thus greatly improving weld strength and welding quality.

[0040] The axisymmetric transverse ultrasonic device designed in this invention can regulate and constrain the welding arc, effectively preventing arcing on the sidewall, while concentrating heat, increasing penetration depth, and improving the welding quality of medium and thick plates.

[0041] The ultrasonic micro-forging equipment designed in this invention can move synchronously with the welding torch to fully stir the molten pool, homogenize the temperature and composition, eliminate bubbles and residual stress, refine the grains, and greatly improve the weld strength.

[0042] The ultrasonic micro-forging equipment designed according to this invention, when placed at the bottom of the weld, can support and shape the back of the weld, prevent back collapse and weld beads, make the back of the weld smooth and shape, improve welding quality, and meet the forming requirements of the workpiece.

[0043] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A hybrid welding device for ultrasonic-assisted laser and MIG arc welding, characterized in that, The device includes a MIG arc welding gun (2) connected to the positive terminal of the power supply, a workpiece (9) to be welded connected to the negative terminal of the power supply, and a Y-shaped bevel (10) on the upper part of the workpiece (9). The MIG arc welding gun (2) is located in front of the laser (1) in the welding direction of the Y-shaped groove (10) and at a certain angle to the workpiece (9) to be welded. Two first ultrasonic generators (5) arranged axially symmetrically are connected by a connecting base (6). Each first ultrasonic generator (5) is connected to an ultrasonic impact needle (4). The two ultrasonic impact needles (4) are axially symmetrically distributed on both sides of the arc welding gun (2). The second ultrasonic generator (8) is located directly below the molten pool formed by the welding of the Y-shaped groove (10).

2. The ultrasonic-assisted laser and MIG arc hybrid welding device according to claim 1, characterized in that, The roller (7) connected to the second ultrasonic generator (8) directly contacts the bottom of the workpiece (9) to be welded and moves along the welding direction.

3. The ultrasonic-assisted laser and MIG arc hybrid welding device according to claim 1, characterized in that, The first ultrasonic generator (5) has an ultrasonic frequency of 20-35kHz and a power of 600-1200W. The second ultrasonic generator (8) has an ultrasonic frequency of 20-50kHz and a power of 600-1200W.

4. The ultrasonic-assisted laser and MIG arc hybrid welding device according to claim 1, characterized in that, The bevel angle of one side of the Y-shaped bevel (10) is 30°-45°.

5. A method for ultrasonic-assisted laser and MIG arc hybrid welding, characterized in that, This method is implemented in the ultrasonic-assisted laser and MIG arc hybrid welding apparatus according to any one of claims 1-4, and the method includes: S1, turn on the first ultrasonic generator (5) with axial symmetry and transverse distribution, and transmit the vibration to the tip of the welding wire (3) at the head of the MIG arc welding gun (2) through the ultrasonic impact needle (4); S2, turn on the second ultrasonic generator (8), and the roller (7) connected to the second ultrasonic generator (8) contacts the bottom of the workpiece (9) to be welded. Ultrasonic micro-forging is achieved on the bottom of the workpiece (9) through the high-frequency vibration of the roller (7). S3, simultaneously turn on the power supply of the MIG arc welding gun (2) and the laser (1) to perform welding.

6. The ultrasonic-assisted laser and MIG arc hybrid welding method according to claim 5, characterized in that, Step S3, welding includes: When the arc of the MIG arc welding gun (2) is ignited, the first ultrasonic generator (5) with axisymmetric transverse distribution acts on the ultrasonic impact needle (4) with high frequency vibration. The arc heat source and laser spot are concentrated at the bottom of the Y-shaped groove (10) of the workpiece to be welded (9) for welding. During the welding process, the welding wire (3) melts and drips down, forming a molten pool under the action of high heat. The second ultrasonic generator (8) at the bottom stirs the molten pool through ultrasonic vibration and the generated acoustic flow effect and cavitation effect.

7. The ultrasonic-assisted laser and MIG arc hybrid welding method according to claim 5, characterized in that, In step S3, during welding, the laser (1) uses a laser power of 3-9kW, an arc voltage of 20-30V, and a welding speed of 0.3-1.5m / min.

8. The ultrasonic-assisted laser and MIG arc hybrid welding method according to claim 5, characterized in that, Application of the ultrasonic-assisted laser and MIG arc hybrid welding method in medium and thick plate welding.

9. The ultrasonic-assisted laser and MIG arc hybrid welding method according to claim 5, characterized in that, The ultrasonic-assisted laser and MIG arc hybrid welding method is mounted on a computer terminal controller and executed.

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