An ultra-narrow gap laser hybrid welding method

Abstract

The application discloses a kind of ultra-narrow gap laser composite welding methods, laser beam uses three-row layout, middle row beam is located in weld center, and each set of row beam is arranged at the edge of groove on the left and right sides of weld, during welding process, effective action width of laser beam is controlled as 6mm, using positive defocusing mode, two welding wires are symmetrically arranged in the left and right sides of narrow gap groove, and welding wire feeding position is located at 5mm~10mm in front of laser beam, when plate thickness T≤20mm, welding speed of 300-500mm / min is used, when plate thickness T>20mm, welding speed of 100-300mm / min is used, and welding pool is protected by two-way collaborative delivery protective gas.The application fuses multi-spot adjustable power laser system, double-wire collaborative feeding mechanism and multi-path gas protection scheme, and constructs efficient, stable narrow gap welding technology system.Effectively solve a series of problems such as that welding groove sidewall is not fused, weld center is not penetrated, weld porosity defect and other problems that lead to unqualified weld metal mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of marine shipbuilding and design, and specifically relates to an ultra-narrow gap laser composite welding method. Background Technology

[0002] In recent years, narrow-gap welding has been widely used in large equipment such as ships, pressure vessels, and offshore engineering platforms. With its advantages of reducing filler material consumption, lowering welding heat input, and effectively suppressing welded component deformation, narrow-gap welding has become the mainstream technology for welding thick plates. However, existing laser-based hybrid welding technologies face significant bottlenecks in practical applications: 1. Traditional single-spot laser welding is difficult to adapt to the cladding requirements of 6-10mm narrow gaps, easily leading to multiple problems such as incomplete fusion of the bevel sidewalls, incomplete penetration of the weld center, and porosity, affecting the performance of the welded structure; 2. Insufficient synergy between the dual-wire and laser, resulting in wire position deviation and energy distribution imbalance, leads to poor weld formation consistency and easily produces defects such as undercut, incomplete fusion, and weld beads; 3. The shielding gas delivery path is singular, unable to effectively protect the weld pool from formation to solidification, resulting in frequent defects such as porosity and oxidation; 4. The rigid laser beam power adjustment method is difficult to match the differentiated fusion requirements of different areas such as the narrow gap sidewalls and center, limiting its adaptability. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides an ultra-narrow gap laser hybrid welding method, aiming to avoid defects such as incomplete fusion of the weld bevel sidewalls, incomplete penetration at the weld center, and weld porosity that lead to substandard mechanical properties of the weld metal. The technical solution adopted is as follows: A method for ultra-narrow gap laser composite welding, wherein the welding groove adopts an I-type groove, or the straight edge of the groove adopts a slight angle, and the width of the groove gap is 6mm~10mm.

[0004] The laser beams are arranged in three rows, with three beams in each row, for a total of nine beams. The middle row of beams is located at the center of the weld, and a row of beams is set on each of the left and right bevel edges of the weld. All nine laser beams have independent power adjustment functions, and different laser beam power can be selected according to different welding layers, such as root pass or fill pass.

[0005] During the welding process, the effective width of the laser beam is controlled at 6mm, and a positive defocusing method is adopted, with a defocusing amount of 5mm~15mm. The effective range of the laser beam is expanded or reduced by adjusting the defocusing amount.

[0006] The dual-wire synchronous welding mode is adopted, with two welding wires symmetrically arranged on the left and right sides of the narrow gap bevel. The welding wires are fed in 5mm to 10mm in front of the laser beam, and the diameter of the welding wires is 1.2mm to 1.6mm.

[0007] When the plate thickness T ≤ 20 mm, a welding speed of 300~500 mm / min should be used. When the plate thickness T > 20 mm, a welding speed of 100~300 mm / min should be used.

[0008] The shielding gas used is high-purity argon gas with a purity ≥99.99%. It is delivered via two coordinated gas streams to protect the weld pool. The first shielding gas stream is delivered through the built-in gas channel of the laser welding torch, with a flow rate of 2-5 L / min. This first stream primarily protects the laser lens and the instantaneous weld pool within the laser's effective area. The second shielding gas stream is delivered symmetrically to both sides of the bevel, with its effective position lags behind the laser beam's point of action by 8-12 mm, and a flow rate of 15-20 L / min. This second stream primarily protects the solidified weld area.

[0009] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, the bevel gap width is 7mm~9mm.

[0010] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, the slight angle of the straight edge of the bevel is no greater than 5°.

[0011] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, the bevel straight edge uses a slight angle of 1°~3°.

[0012] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, preheating is required before the welding wire is fed in.

[0013] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, when the plate thickness T≤20mm, a welding speed of 300~400mm / min is adopted; when the plate thickness T>20mm, a welding speed of 200~300mm / min is adopted.

[0014] Furthermore, in the aforementioned ultra-narrow gap laser composite welding method, the gas flow rate of the built-in gas channel of the laser welding torch is 3-4 L / min.

[0015] The beneficial effects of this invention are: 1. Significantly improved weld fusion quality. By employing a multi-spot power independent adjustment scheme, combined with positive defocusing technology, the problem of incomplete fusion defects at the bevel positions on both sides of narrow gap welds has been completely resolved.

[0016] 2. Effective control of thermal deformation. The dual-wire preheating design reduces the heat input of laser welding, and the wide-range adjustable welding speed reduces the overall heat input accumulation of the welded components. Compared with traditional welding methods, the welding deformation is reduced by 30%-50%.

[0017] 3. Extremely low weld defect rate. The dual-path argon gas protection system, combined with the delayed protection effect of the shielding gas, isolates the weld pool from air interference throughout the welding process, reducing the probability of defects such as weld porosity and oxidation to below 0.5%.

[0018] 4. Wide range of applications. It can cover most narrow-gap welding scenarios for thick plates, and can perform high-quality welding with adjustable beam power for various base materials such as carbon steel, stainless steel, and high-strength steel. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the bevel of the present invention.

[0020] Figure 2 This is a schematic diagram of the laser beam distribution.

[0021] Figure 3 This is a schematic diagram of the beam power for drilling the bottom layer weld seam.

[0022] Figure 4 This is a schematic diagram of the beam power of the filler layer weld. Detailed Implementation

[0023] The invention will be further described with reference to the accompanying drawings.

[0024] A method for ultra-narrow gap laser hybrid welding includes: 1. Narrow gap bevel design: The welding bevel adopts an I-type bevel (or a slight angle on the straight edge of the bevel). The width of the bevel gap should be 6-10mm (7-9mm is the optimal welding gap). If a slight angle is used on the straight edge of the bevel, it should not exceed 5° (1°-3° is optimal). See details of the bevel design scheme. Figure 1 As shown, this bevel design significantly reduces the amount of welding material used and also lowers the cost of bevel processing. The narrow-gap bevel design provides a structural basis for subsequent welding process optimization.

[0025] 2. Multi-spot tunable laser system solution: The laser beams adopt a three-row layout, with a total of 9 beams (i.e., three rows of laser beams, 3 beams per row). See details. Figure 2 As shown, a row of laser beams is positioned at the center of the weld, with another row positioned along the bevel edges on both sides. All nine laser beams have independent power adjustment capabilities, allowing for the selection of different beam powers depending on the welding layer, such as the root pass or fill pass. During welding, the effective width of the laser beam is controlled at 6mm, employing a positive defocusing method. The defocusing amount is adjusted according to the plate thickness (typically within the range of 5-15mm). This adjustment expands and contracts the effective range of the laser beam, preventing incomplete fusion defects on both sides of the bevel and reducing the risk of porosity.

[0026] 3. Dual-wire collaborative feeding system: This system employs a dual-wire synchronous welding mode, with two welding wires symmetrically arranged on the left and right sides of a narrow-gap bevel. The welding wires are fed in 5-10mm in front of the laser beam. By preheating the welding wires, the laser heat input load is reduced. The welding wire diameter is selected based on the gap width, typically using 1.2-1.6mm welding wire to ensure compatibility between the welding wire and the bevel and high deposition efficiency.

[0027] 4. Welding process parameters: For detailed information on laser beam power selection, please refer to [link / reference]. Figure 3 As shown, during the actual welding process, fine adjustments can be made based on the weld pool deposition to achieve the optimal result of no welding defects. The welding speed range is 100-500 mm / min (in actual welding, a welding speed of 200-400 mm / min is more suitable). The welding speed adjustment range according to different plate thicknesses is as follows: when the plate thickness T≤20mm, a welding speed of 300-500 mm / min is used; when the plate thickness T>20mm, a welding speed of 100-300 mm / min is used.

[0028] 5. Multi-path gas protection system: High-purity argon gas with a purity ≥99.99% is used as the shielding gas. Two coordinating gas delivery paths protect the weld pool. The first shielding gas path is located within the laser welding torch, with a flow rate of 2-5 L / min (3-4 L / min provides optimal protection). This path primarily protects the laser lens and the instantaneous weld pool within the laser's effective area. The second shielding gas path consists of gas delivery devices symmetrically positioned on both sides of the bevel, acting 8-12 mm behind the laser beam's point of impact, with a flow rate of 15-20 L / min. This path focuses on protecting the solidification zone of the weld. This dual-path gas protection system achieves comprehensive protection of the weld pool from formation to solidification, eliminating blind spots throughout the entire process.

Claims

1. A method for ultra-narrow gap laser composite welding, characterized in that, The welding groove adopts an I-type groove, or the straight edge of the groove adopts a slight angle, and the width of the groove gap is 6mm~10mm; The laser beams are arranged in three rows, with three beams in each row, for a total of nine beams. The middle row of beams is located at the center of the weld, and a row of beams is set on each of the left and right bevel edges of the weld. All nine laser beams have independent power adjustment functions, and different laser beam power can be selected according to different welding layers, such as root pass or fill pass. During the welding process, the effective width of the laser beam is controlled to be 6mm, and a positive defocusing method is adopted. The defocusing amount is 5mm~15mm, and the effective range of the laser beam is expanded and reduced by adjusting the defocusing amount. The dual-wire synchronous welding mode is adopted, with two welding wires symmetrically arranged on the left and right sides of the narrow gap bevel. The welding wires are fed in 5mm to 10mm in front of the laser beam, and the diameter of the welding wires is 1.2mm to 1.6mm. When the plate thickness T ≤ 20mm, a welding speed of 300-500mm / min should be used; when the plate thickness T > 20mm, a welding speed of 100-300mm / min should be used. The shielding gas is high-purity argon gas with a purity of ≥99.99%. The shielding gas is delivered in two ways to protect the weld pool. The first shielding gas is delivered through the built-in gas channel of the laser welding torch, with a gas flow rate of 2-5 L / min. The first shielding gas mainly protects the instantaneous weld pool in the laser lens and the laser action area. The second shielding gas is delivered by gas supply devices on both sides of the bevel, symmetrically arranged on both sides of the bevel. The action position is 8mm~12mm behind the laser beam action point, and the gas flow rate is 15~20 L / min. The second shielding gas focuses on protecting the solidification area of ​​the weld.

2. The ultra-narrow gap laser composite welding method according to claim 1, characterized in that, The width of the bevel gap is 7mm~9mm.

3. The ultra-narrow gap laser composite welding method according to claim 1, characterized in that, The slight angle used for the straight edge of the bevel should not exceed 5°.

4. The ultra-narrow gap laser composite welding method according to claim 3, characterized in that, The beveled straight edge uses a slight angle of 1° to 3°.

5. The ultra-narrow gap laser composite welding method according to claim 1, characterized in that, The welding wire needs to be preheated before it is fed in.

6. The ultra-narrow gap laser composite welding method according to claim 1, characterized in that, When the plate thickness T≤20mm, a welding speed of 300~400mm / min is used; when the plate thickness T>20mm, a welding speed of 200~300mm / min is used.

7. The ultra-narrow gap laser composite welding method according to claim 1, characterized in that, The gas flow rate of the built-in gas channel of the laser welding torch is 3-4 L / min.

Images