Dissimilar material oscillation laser welding method based on synchronous electromagnetic regulation and control

Abstract

The invention belongs to the field of dissimilar material laser welding, and discloses a dissimilar material oscillation laser welding method based on synchronous electromagnetic regulation and control, which comprises the following steps: according to the shape and size of two dissimilar material welding test plates, determining the clamping mode of the two welding test plates, cleaning the surfaces of the steel plates, and clamping the steel plates on a welding workbench by using a clamp; an oscillation laser head, a protective gas nozzle and an electromagnet are arranged above the welding test plate, an alternating electromagnetic coil is arranged below the welding test plate, and the oscillation path and oscillation parameters of a laser beam are determined according to the welding seam width and the mechanical property requirement; proper welding process parameters and electromagnetic parameters are determined by combining the material and the thickness of the welding test plate; and synchronous electromagnetic control oscillation laser welding is conducted according to the set laser beam oscillation path till welding of the two welding test plates is completed. According to the method, the defects of humps, air holes, asymmetry of weld joints and the like can be overcome, and high-quality welding of dissimilar material composite components is achieved.

Description

Technical Field

[0001] The invention relates to a dissimilar material oscillation laser welding method based on synchronous electromagnetic regulation, belonging to the field of dissimilar material laser welding. Background Art

[0002] With the rapid development of modern manufacturing industry, heterogeneous composite components have been widely used in aerospace, rail transit, petrochemical and other fields. Laser welding technology has the advantages of high energy density, fast welding speed, low heat input and small welding deformation, and shows great potential in the manufacture of heterogeneous composite components. The conventional laser welding method is used to process heterogeneous composite components, which is prone to defects such as humps, pores and weld asymmetry, and it is difficult to meet the service performance requirements. Oscillating laser welding technology stirs the molten pool through the periodic oscillation of the laser beam, providing good conditions for the escape of bubbles in the molten pool, and can be used to improve the forming quality of the weld. Electromagnetic assisted laser welding technology induces Lorentz force inside the welding molten pool through electromagnetic field, improves the flow pattern of molten metal in the molten pool, and suppresses humps and pores. At present, a single stable magnetic field is mainly used to improve the quality of laser welding of heterogeneous materials. There are disadvantages such as small magnetic field range and difficult adjustment, which makes it difficult to meet the welding quality improvement requirements under different process conditions. Therefore, it is urgent to propose a heterogeneous material laser welding method with high welding quality and convenient regulation. Summary of the invention

[0003] In order to suppress defects in the welding process of dissimilar materials, the present invention proposes a dissimilar material oscillation laser welding method based on synchronous electromagnetic control, which improves the stability of the small holes in the molten pool during welding, suppresses defects such as humps, pores and weld asymmetry, and thus improves the forming quality of dissimilar material welds and the mechanical properties of welded joints.

[0004] The technical solution of the present invention is as follows: A method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation comprises the following steps:

[0005] (1) Determine the clamping method of the two welding test plates according to the shape and size of the two dissimilar material welding test plates, clean their surfaces and clamp them on the welding workbench respectively with a clamp;

[0006] (2) Arrange an oscillating laser head, a protective gas nozzle and an electromagnet above the welding test plate, and arrange an alternating electromagnetic coil below the welding test plate. Determine the laser beam oscillation path and oscillation parameters according to the weld width and mechanical performance requirements;

[0007] (3) Determine appropriate welding process parameters and electromagnetic parameters based on the material and thickness of the welding test plate;

[0008] (4) Performing synchronous electromagnetic controlled oscillation laser welding according to the set laser beam oscillation path until the welding of the two welding test plates is completed;

[0009] Among them, the welding process parameters include laser power, welding speed, defocus and shielding gas flow; the electromagnetic parameters of the electromagnet are magnetic induction intensity; and the electromagnetic parameters of the alternating electromagnetic coil include magnetic field frequency, magnetic induction intensity and number of coil turns.

[0010] Furthermore, in step (2), the height of the oscillating laser head above the welding test plate is adjusted to obtain a suitable defocus amount; by adjusting the lateral offset distance W1 of the central axis of the oscillating laser head, the energy distribution in the oscillating laser welding molten pool can be adjusted to suppress the asymmetric defects of the weld caused by the difference in thermal properties of dissimilar materials.

[0011] Furthermore, in step (2), the electromagnet above the welding test plate generates a stable magnetic field, the electromagnet moves synchronously with the oscillating laser head along the welding direction, the two electromagnets are symmetrically distributed about the welding test plate butt joint plane, and the alternating electromagnetic coil below the welding test plate generates an alternating magnetic field, the alternating electromagnetic coil moves synchronously with the oscillating laser head along the welding direction; wherein the stable magnetic field can induce Lorentz force inside the molten pool, improve the flow pattern of the molten metal in the molten pool, effectively reduce the flow speed of the molten metal at the rear of the molten pool, suppress hump defects, and also reduce the intensity of the molten metal flow on the rear wall of the small hole, improve the stability of the small hole in the molten pool, and suppress pore defects; the alternating magnetic field can induce induced eddy currents inside the welding test plate and form an induced heat field in the welding test plate, suppress the collapse of the rear wall of the small hole, and reduce the formation of pore defects;

[0012] The spatial distribution of the stable magnetic field can be adjusted by adjusting the lateral distance L1 between the two electromagnets above the welding test plate and the longitudinal distance H1 from the central axis of the electromagnet to the welding test plate; the spatial distribution of the alternating magnetic field can be adjusted by adjusting the lateral offset distance W2 of the central axis of the alternating electromagnetic coil below the welding test plate, the longitudinal distance H2 from the alternating electromagnetic coil to the welding test plate, and the distance L2 between the central axis of the alternating electromagnetic coil and the central axis of the oscillating laser head along the welding direction.

[0013] Furthermore, in step (2), the laser beam oscillation path and oscillation parameters can be selected according to the weld width and mechanical property requirements, wherein the laser beam oscillation path includes circular, sinusoidal and "∞" shapes, and the oscillation parameters include oscillation amplitude and oscillation frequency. The periodic oscillation of the laser beam can produce a stirring effect on the molten pool, improve the flow pattern of the molten metal in the molten pool, and form complex vortices in the molten pool, providing good conditions for the escape of bubbles in the molten pool, suppressing porosity defects, and improving the forming quality of the weld.

[0014] Furthermore, in step (3), the stable magnetic field generated by the electromagnet induces the Lorentz force inside the welding pool, improving the flow pattern of the molten metal in the molten pool; the Lorentz force is closely related to the electromagnetic parameters and the welding test plate material; in order to better analyze the influence of the Lorentz force on the molten pool, the Lorentz force is defined as:

[0015] F=σ(v×B)×B

[0016] Among them, σ is the electrical conductivity of the material, v is the flow rate of the molten metal, and B is the magnetic induction intensity;

[0017] When an alternating current is input into the alternating electromagnetic coil, an alternating magnetic field is formed, which generates induced eddy currents inside the welding test plate, thereby forming an induced heat field in the welding test plate. Under the action of the alternating magnetic field, the heat power density generated by the induced eddy currents in the welding test plate is closely related to the welding test plate material and the induced eddy current density. In order to better analyze the influence of the induced eddy current on the welding test plate, the heat power density generated by the induced eddy current is defined as:

[0018]

[0019] Where, J is the induced eddy current density;

[0020] Affected by the skin effect, the induced eddy currents generated inside the welding test plate are mainly concentrated on the lower surface of the welding test plate. The relationship between the skin depth and the material thickness needs to be considered in the alternating magnetic field. When the skin depth is much smaller than the material thickness, the skin depth can be increased by appropriately reducing the magnetic field frequency to improve the regulating effect of the induced thermal field on the stability of the small hole wall. The skin depth is defined as:

[0021]

[0022] Where μ is the relative magnetic permeability of the material, μ0 is the magnetic permeability of vacuum, and f a is the magnetic field frequency.

[0023] Furthermore, in step (4), 99.99% high-purity argon is selected as the shielding gas in the welding process, and the shielding gas flow rate is selected according to the process requirements; the specific operation of the welding process is to first open the water cooling gate, the air compressor gate and the shielding gas nozzle, and then turn on the laser, the electromagnet and the alternating electromagnetic coil power supply, and then according to the set laser beam oscillation path and welding process parameters, provide energy to the welding test plate through the oscillating laser beam to form a molten pool and a small hole in the welding test plate, and according to the set electromagnetic parameters, the dynamic behavior and stability of the molten pool small hole are regulated by the stable magnetic field and the alternating magnetic field, and finally realize the synchronous electromagnetic regulation of the dissimilar material oscillation laser welding process to obtain a welding joint with good weld formation quality.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention discloses a method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation, which uses a combination of laser beam oscillation and synchronous electromagnetic regulation to suppress defects such as humps, pores and weld asymmetry during the welding process, effectively improves the weld forming quality and joint mechanical properties of dissimilar materials, and realizes high-quality welding of dissimilar material composite components.

[0026] 2. The oscillating laser welding method of dissimilar materials based on synchronous electromagnetic control described in the present invention can improve the dynamic behavior and stability of the small hole in the molten pool in the welding test plate, improve the welding quality through the regulation of the Lorentz force and the induced thermal field, and the regulation is convenient, which can meet the high-quality welding requirements of materials such as low-carbon steel, stainless steel, aluminum alloy and magnesium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall schematic diagram of a method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation according to the present invention;

[0028] Figure 2 for Figure 1 The main view of

[0029] Figure 3 for Figure 1 Right view of;

[0030] In the figure, 1-welding test plate A, 2-welding seam, 3-welding test plate B, 4-shielding gas nozzle, 5-oscillating laser beam, 6-oscillating laser head, 7-electromagnet A, 8-small hole, 9-molten pool, 10-electromagnet B, 11-alternating electromagnetic coil. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention based on synchronous electromagnetic control of the oscillating laser welding method of dissimilar materials clearer, the following is a detailed description with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention, and the scope of protection of the present invention includes but is not limited to the following embodiments.

[0032] like Figure 1 As shown, this embodiment is specifically a method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control. The welding test plate A1 is Q235 low carbon steel, and the welding test plate B3 is 316L stainless steel, both of which have a thickness of 5mm. The shielding gas blown by the shielding gas nozzle 4 is 99.99% high purity argon gas. In this embodiment, the welding joint is a butt joint, and the welding method is autogenous welding without filling metal.

[0033] like Figure 2 and Figure 3As shown, this embodiment adjusts the energy distribution and magnetic field distribution during the oscillation laser welding process by adjusting the lateral offset distance W1 of the central axis of the oscillation laser head 6, the lateral distance L1 between the electromagnet A7 and the electromagnet B10, the longitudinal distance H1 from the central axis of the electromagnet A7 and the electromagnet B10 to the welding test plate A1 and the welding test plate B3, the lateral offset distance W2 of the central axis of the alternating electromagnetic coil 11, the longitudinal distance H2 from the alternating electromagnetic coil 11 to the welding test plate A1 and the welding test plate B3, and the distance L2 between the central axis of the alternating electromagnetic coil 11 and the central axis of the oscillation laser head 6 along the welding direction. The present invention provides a method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation, the welding process is stable and controllable, and defects such as humps, pores and weld asymmetry can be effectively suppressed, the weld formation quality is high, and the mechanical properties of the joint are good.

[0034] The present embodiment provides a method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation, which comprises the following steps:

[0035] (1) Prepare the required welding test plate A1 and welding test plate B3; in this embodiment, Q235 low carbon steel with a size of 200 mm × 100 mm × 5 mm is selected as the welding test plate A1, and 316L stainless steel with a size of 200 mm × 100 mm × 5 mm is selected as the welding test plate B3; clean the surfaces of the welding test plate A1 and the welding test plate B3 to remove oxides and oil stains on the surfaces; clamp the welding test plate A1 and the welding test plate B3 on the welding workbench by a clamp so that the welding test plate A1 and the welding test plate B3 are in close contact;

[0036] (2) Adjust the height of the oscillating laser head 6 so that the defocus amount remains at 0 mm, adjust the lateral offset distance W1 of the central axis of the oscillating laser head 6 to 0 mm to 2 mm, set the laser beam oscillation path to a circle, and the oscillation parameters are: oscillation amplitude 0.4 mm to 1.2 mm, oscillation frequency 60 Hz to 140 Hz; adjust the protective gas nozzle 4 so that it is aligned with the position of the oscillating laser welding molten pool 9 and the small hole 8; adjust the lateral distance L1 between the electromagnet A7 and the electromagnet B10 to 40 mm to 60 mm, the longitudinal distance H1 from the central axis of the electromagnet A7 and the electromagnet B10 to the welding test plate A1 and the welding test plate B3 to 30 mm to 50 mm, the lateral offset distance W2 of the central axis of the alternating electromagnetic coil 11 to 0 mm to 10 mm, the longitudinal distance H2 from the alternating electromagnetic coil 11 to the welding test plate A1 and the welding test plate B3 to 5 mm to 10 mm, and the distance L2 between the central axis of the alternating electromagnetic coil 11 and the central axis of the oscillating laser head 6 along the welding direction to 0 mm to 10 mm;

[0037] (3) Based on the material and thickness of the welding test plate A1 and the welding test plate B3, determine the appropriate welding process parameters and electromagnetic parameters. In this embodiment, the welding process parameters are: laser power 2500W~5000W, welding speed 2.5m / min~10.0m / min, shielding gas flow rate 10L / min~15L / min; the electromagnetic parameters of the electromagnet A7 and the electromagnet B10 are: magnetic induction intensity 30mT~100mT; the electromagnetic parameters of the alternating electromagnetic coil 11 are: magnetic field frequency 20kHz~80kHz, magnetic induction intensity 30mT~100mT, and coil turns 50 turns~100 turns;

[0038] (4) Perform synchronous electromagnetic controlled oscillation laser welding according to the set laser beam oscillation path, provide energy to the welding test plate through the oscillating laser beam 5, form a molten pool 9 and a small hole 8 in the welding test plate, until the welding of the welding test plate A1 and the welding test plate B3 is completed.

[0039] Through the above embodiments, the purpose, method and content of the present invention are further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. The present invention can be applied to other suitable scenarios in the field of welding through appropriate modifications. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic regulation, characterized in that: The steps include: (1) Determine the clamping method of the two welding test plates according to the shape and size of the two dissimilar material welding test plates, clean their surfaces and clamp them on the welding workbench respectively with a clamp; (2) Arrange an oscillating laser head, a protective gas nozzle and an electromagnet above the welding test plate, and arrange an alternating electromagnetic coil below the welding test plate. Determine the laser beam oscillation path and oscillation parameters according to the weld width and mechanical performance requirements; (3) Determine appropriate welding process parameters and electromagnetic parameters based on the material and thickness of the welding test plate; (4) Performing synchronous electromagnetic controlled oscillation laser welding according to the set laser beam oscillation path until the welding of the two welding test plates is completed; Among them, the welding process parameters include laser power, welding speed, defocus and shielding gas flow; the electromagnetic parameters of the electromagnet are magnetic induction intensity; and the electromagnetic parameters of the alternating electromagnetic coil include magnetic field frequency, magnetic induction intensity and number of coil turns.

2. The method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control according to claim 1 is characterized in that: In step (2), the height of the oscillating laser head above the welding test plate is adjusted to obtain a suitable defocus amount; by adjusting the lateral offset distance W1 of the central axis of the oscillating laser head, the energy distribution in the oscillating laser welding molten pool can be adjusted to suppress the asymmetric defects of the weld caused by the difference in thermal properties of dissimilar materials.

3. The method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control according to claim 1 is characterized in that: In step (2), the electromagnet above the welding test plate generates a stable magnetic field, and the electromagnet moves synchronously with the oscillating laser head along the welding direction. The two electromagnets are symmetrically distributed about the welding test plate butt joint plane, and the alternating electromagnetic coil below the welding test plate generates an alternating magnetic field, and the alternating electromagnetic coil moves synchronously with the oscillating laser head along the welding direction; wherein the stable magnetic field can induce Lorentz force inside the molten pool, improve the flow pattern of molten metal in the molten pool, effectively reduce the flow speed of molten metal at the rear of the molten pool, suppress hump defects, and also reduce the intensity of molten metal flow on the rear wall of the small hole, improve the stability of the small hole in the molten pool, and suppress pore defects; the alternating magnetic field can induce induced eddy currents inside the welding test plate and form an induced heat field in the welding test plate, suppress the collapse of the rear wall of the small hole, and reduce the formation of pore defects; The spatial distribution of the stable magnetic field can be adjusted by adjusting the lateral distance L1 between the two electromagnets above the welding test plate and the longitudinal distance H1 from the central axis of the electromagnet to the welding test plate; the spatial distribution of the alternating magnetic field can be adjusted by adjusting the lateral offset distance W2 of the central axis of the alternating electromagnetic coil below the welding test plate, the longitudinal distance H2 from the alternating electromagnetic coil to the welding test plate, and the distance L2 between the central axis of the alternating electromagnetic coil and the central axis of the oscillating laser head along the welding direction.

4. The method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control according to claim 1 is characterized in that: In step (2), the laser beam oscillation path and oscillation parameters can be selected according to the weld width and mechanical property requirements, wherein the laser beam oscillation path includes circular, sinusoidal and "∞" shapes, and the oscillation parameters include oscillation amplitude and oscillation frequency. The periodic oscillation of the laser beam can stir the molten pool, improve the flow pattern of the molten metal in the molten pool, and form complex vortices in the molten pool, providing good conditions for the escape of bubbles in the molten pool, suppressing porosity defects, and improving the forming quality of the weld.

5. The method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control according to claim 1 is characterized in that: In step (3), the stable magnetic field generated by the electromagnet induces the Lorentz force inside the welding pool, improving the flow pattern of the molten metal in the molten pool; the Lorentz force is closely related to the electromagnetic parameters and the welding test plate material; in order to better analyze the influence of the Lorentz force on the molten pool, the Lorentz force is defined as: F=σ(v×B)×B Among them, σ is the electrical conductivity of the material, v is the flow rate of the molten metal, and B is the magnetic induction intensity; When an alternating current is input into the alternating electromagnetic coil, an alternating magnetic field is formed, which generates induced eddy currents inside the welding test plate, thereby forming an induced heat field in the welding test plate. Under the action of the alternating magnetic field, the heat power density generated by the induced eddy currents in the welding test plate is closely related to the welding test plate material and the induced eddy current density. In order to better analyze the influence of the induced eddy current on the welding test plate, the heat power density generated by the induced eddy current is defined as: Where, J is the induced eddy current density; Affected by the skin effect, the induced eddy currents generated inside the welding test plate are mainly concentrated on the lower surface of the welding test plate. The relationship between the skin depth and the material thickness needs to be considered in the alternating magnetic field. When the skin depth is much smaller than the material thickness, the skin depth can be increased by appropriately reducing the magnetic field frequency to improve the regulating effect of the induced thermal field on the stability of the small hole wall. The skin depth is defined as: Where μ is the relative magnetic permeability of the material, μ0 is the magnetic permeability of vacuum, and f a is the magnetic field frequency.

6. The method for oscillating laser welding of dissimilar materials based on synchronous electromagnetic control according to claim 1 is characterized in that: In step (4), 99.99% high-purity argon gas is selected as the shielding gas in the welding process, and the shielding gas flow rate is selected according to the process requirements; the specific operation of the welding process is to first open the water cooling gate, the air compressor gate and the shielding gas nozzle, and then turn on the laser, the electromagnet and the alternating electromagnetic coil power supply, and then according to the set laser beam oscillation path and welding process parameters, the oscillating laser beam is used to provide energy to the welding test plate to form a molten pool and a small hole in the welding test plate, and the dynamic behavior and stability of the molten pool small hole are regulated by a stable magnetic field and an alternating magnetic field according to the set electromagnetic parameters, and finally the synchronous electromagnetic regulation of the dissimilar material oscillation laser welding process is realized to obtain a welding joint with good weld formation quality.

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