Construction method of t-joint welding and laser welding gun

Abstract

The application provides a T-shaped joint welding construction method and a laser welding gun, and the construction method comprises the following steps: S1, installing ship body structure steel plates in a T-shaped corner joint form; S2, performing welding preparation treatment on the ship body structure steel plates; S3, using the laser welding gun to perform positioning welding on the joint of the ship body structure steel plates; and S4, performing cover welding on the welding seam of the positioning welding by adopting a flux-cored gas shielded welding. The application adopts the process of combining laser positioning welding with gas shielded cover welding, effectively reduces heat input by controlling the welding gun angle to be an acute angle, improves the welding seam forming quality, and is suitable for T-shaped corner joint welding operation in ship building.

Description

Technical Field

[0001] This invention relates to the field of welding technology in shipbuilding, and in particular to a construction method for welding T-joints and a laser welding gun. Background Technology

[0002] Currently, tack welding of ship hull structural steel mainly relies on two processes: shielded metal arc welding (SMAW) and flux-cored gas shielded welding (FCAW). However, both methods have significant limitations in practical applications. The core problem lies in the excessive heat input, which often results in tack weld leg sizes far exceeding the reasonable range required by the process, sometimes even reaching levels comparable to the final weld. Excessive heat input not only leads to uncontrolled weld penetration and width but also increases the width of the heat-affected zone, exacerbating the coarsening and hardening tendency of the base metal, adversely affecting the joint's toughness and crack resistance. Simultaneously, excessively large tack weld legs often require extensive grinding and finishing before subsequent final welding, increasing construction time and operating costs. More importantly, excessively large weld leg sizes create localized stress concentrations, restricting the free deformation of the structure and easily inducing additional stress and deformation during welding, thus affecting overall assembly accuracy and weld quality. Therefore, while existing processes meet the basic functions of tack connections, they also reveal systemic deficiencies in heat control, forming quality, and the efficiency of subsequent processes, urgently requiring improvement through optimization of welding methods and process parameters. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of inaccurate control of welding torch angle and unstable welding quality in the laser welding of T-shaped corner joints of ships in the prior art, and to provide a construction method and laser welding torch for welding T-shaped joints.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] A construction method for welding T-joints includes the following steps: S1: Installing the hull structure steel plates in the form of T-joints; S2: Preparing the hull structure steel plates for welding; S3: Using a laser welding gun to perform tack welding on the joints of the hull structure steel plates; S4: Using flux-cored gas shielded welding to perform cover welding on the weld of the tack weld.

[0006] In this scheme, after completing the installation and pre-welding preparation of the T-shaped corner joint through S1 and S2, laser welding gun is first used for positioning welding. This allows the laser beam, guided at an acute angle, to effectively act on the root of the T-shaped corner joint, achieving precise positioning welding. The handheld laser welding used for positioning welding, due to its small weld point size and extremely narrow heat-affected zone, avoids the geometric interference and weld defects caused by the protrusion of traditional large weld points, ensuring a smooth and uniform weld formation in the subsequent FCAW (Fluid-Cored Gas Welding). It also eliminates the grinding process required by traditional methods. Laser positioning welding has the advantages of low heat input and controllable penetration depth, significantly reducing the weld leg size of the positioning weld and avoiding the coarsening of the microstructure and stress concentration problems caused by excessive heat input in traditional positioning welding. Simultaneously, the capping welding using gas shielded welding ensures the strength and formation quality of the final weld. The combination of these two methods effectively reduces the adverse effects of welding heat input on the base material, improving welding quality and efficiency.

[0007] Preferably, step S2 further includes preheating and dehumidifying the hull structure steel plate.

[0008] In this solution, the hull structure steel plates are preheated and dehumidified before welding. Preheating reduces the temperature gradient of the steel plates, reduces the concentration of welding thermal stress, and prevents the generation of welding cracks. Dehumidification removes moisture from the surface of the steel plates, avoiding the generation of hydrogen pores due to moisture evaporation during welding, and further improving the welding quality.

[0009] Preferably, the diameter of the welding wire in the laser welding gun is in the range of 1.2~1.6mm.

[0010] In this solution, by controlling the diameter of the welding wire in the laser welding gun within the range of 1.2~1.6mm, the diameter of the welding wire is matched with the energy density and molten pool size of the laser welding, ensuring that the welding wire can fully melt and uniformly fill the weld, thus avoiding the problems of insufficient filling caused by an excessively thin welding wire or incomplete melting caused by an excessively thick welding wire.

[0011] Preferably, the diameter of the flux-cored welding wire used in the flux-cored gas shielded welding is in the range of 1.2~1.6mm.

[0012] In this scheme, the diameter of the flux-cored welding wire is consistent with that of the laser welding wire, which ensures good matching of weld dimensions for tack welding and capping welding, thus improving the overall welding quality.

[0013] Preferably, step S3 further includes the laser power of the laser welding gun being between 30% and 60%.

[0014] In this solution, by controlling the laser power within the range of 30% to 60%, the laser energy is sufficient to melt the welding wire and the base material to form a tack weld. At the same time, since the tack weld stage does not require complete penetration of the joint, the lower power is sufficient to meet the tack weld requirements, avoiding the problems of excessive melting and excessive heat input caused by excessive power, and effectively controlling the weld leg size of the tack weld.

[0015] Preferably, step S3 further includes a wire feeding speed range of 40~60mm / min for the laser welding gun.

[0016] In this scheme, by controlling the wire feeding speed within the range of 40~60mm / min, the wire supply speed is coordinated with the melting speed under 30%~60% laser power, ensuring the fullness of the locating weld filling, avoiding weld depression caused by too slow wire feeding or accumulation defects caused by too fast wire feeding, and ensuring the forming quality of the locating weld.

[0017] Preferably, step S3 further includes a laser swing range of 3~5mm for the laser welding gun.

[0018] In this solution, by controlling the laser swing amplitude within the range of 3~5mm, the laser beam can achieve appropriate swing coverage in the weld width direction, ensuring that the base materials on both sides of the T-shaped corner joint can achieve sufficient fusion, while the swing amplitude is not too large, which would cause the heat input to be too dispersed, thus balancing the efficiency of the tack welding and the forming quality.

[0019] Preferably, step S3 further includes a laser welding gun head oscillation frequency range of 20~40Hz.

[0020] In this scheme, by controlling the gun head oscillation frequency within the range of 20~40Hz, the laser beam can reciprocate and scan the weld area at an appropriate frequency, which ensures sufficient stirring of the molten pool and gas escape, while preventing the welding process from becoming unstable due to excessive frequency, thus further improving the formation of the positioning weld.

[0021] Preferably, step S3 further includes an angle between the laser welding gun and the vertically placed steel plate during the movement of the laser welding gun, which is in the range of 40° to 50°.

[0022] In this solution, by limiting the angle between the laser welding gun and the vertical steel plate to a range of 40° to 50°, the laser beam can be optimally applied to the root region of the T-shaped corner joint within this angle range. This angle range takes into account both the penetration depth of the laser on the vertical steel plate and the fluidity of the molten pool, avoiding insufficient penetration due to an excessively small angle or poor weld formation due to an excessively large angle.

[0023] Preferably, step S3 further includes an angle between the laser welding gun and the horizontally placed steel plate during the movement of the laser welding gun, which is in the range of 70° to 80°.

[0024] In this solution, by limiting the angle between the laser welding gun and the horizontal steel plate to a range of 70°~80°, the laser beam acts on the upper surface of the horizontal steel plate at a near-vertical angle, which can obtain sufficient penetration depth with a small heat input. At the same time, this application is matched with the vertical steel plate at an angle of 40°~50°, which optimizes the angle of the welding gun in both directions and ensures the fusion quality on both sides of the T-shaped corner joint.

[0025] Preferably, step S3 further includes the laser welding gun spraying gas into the weld seam during the welding process, wherein the gas is argon and the argon gas flow rate is 15~20L / min.

[0026] In this method, by injecting argon shielding gas into the weld area and controlling the flow rate within the range of 15~20L / min, the weld pool and heat-affected zone can be effectively protected from contamination by oxygen and nitrogen in the air, preventing oxidation of the weld area. Argon, as an inert gas, does not chemically react with the molten metal, making it suitable as a shielding gas for laser welding.

[0027] Preferably, the gas used in the gas shielded welding torch is carbon dioxide, and the gas flow rate is 15~25L / min.

[0028] In this solution, carbon dioxide is used as the shielding gas in gas-shielded cap welding. During welding, carbon dioxide decomposes to produce oxygen atoms, which refines the molten droplets, improves the fluidity of the weld pool, and results in a well-formed weld. Carbon dioxide is inexpensive and suitable for the high-flow-rate protection requirements of cap welding.

[0029] Preferably, in step S4, the moving speed of the gas shielded welding torch is 270~370 mm / min.

[0030] In this design, by controlling the moving speed of the gas shielded welding torch within the range of 270~370 mm / min, the heat input of the cover weld is matched with the weld size of the tack weld. Within this speed range, gas shielded welding can fully cover the tack weld, forming a solid cover layer, while maintaining moderate production efficiency.

[0031] A laser welding gun is used in the construction method of welding T-joints as described above. The laser welding gun includes a welding gun body and a wire feed tube, and the wire feed tube is hinged to the welding gun body through a double-link structure.

[0032] In this design, the wire feed tube is hinged to the welding torch body via a double-link structure, allowing the wire feed tube to adaptively adjust its angle according to changes in the welding torch's posture. This ensures that the welding wire is always fed into the weld pool at a stable angle. The double-link structure provides a wider angle adjustment range and greater flexibility, enabling the wire feed tube angle to automatically adjust when welding at different positions on a T-joint, ensuring the continuity and stability of the wire feeding process.

[0033] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0034] The positive and progressive effects of this invention are as follows:

[0035] After completing the installation and pre-welding preparation of the T-shaped corner joint using S1 and S2, laser welding is first used for positioning welding. The welding torch is kept at an acute angle to the horizontal steel plate, allowing the laser beam to effectively act on the root of the T-shaped corner joint under the guidance of the acute angle, achieving precise positioning welding. The handheld laser welding used for positioning welding, due to its small weld point size and extremely narrow heat-affected zone, avoids the geometric interference and weld defects caused by the protrusion of traditional large weld points, ensuring a smooth and uniform FCAW weld formation. It also eliminates the grinding process required by traditional methods. Laser positioning welding has the advantages of low heat input and controllable penetration depth, significantly reducing the weld leg size of the positioning weld and avoiding the coarsening of the microstructure and stress concentration problems caused by excessive heat input in traditional positioning welding. Simultaneously, gas shielded welding is used for capping, ensuring the strength and formation quality of the final weld. The combination of these two methods effectively reduces the adverse effects of welding heat input on the base material, improving welding quality and efficiency. Attached Figure Description

[0036] Figure 1 This is a flowchart of a preferred embodiment of the construction method for welding T-joints according to the present invention.

[0037] Figure 2 This is a schematic diagram (I) illustrating the construction method of welding a T-joint according to a preferred embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram (II) illustrating the construction method of welding a T-joint according to a preferred embodiment of the present invention.

[0039] Figure 4 This is a schematic diagram (III) illustrating the construction method of welding T-joints according to a preferred embodiment of the present invention.

[0040] Figure 5 This is a cross-sectional schematic diagram of a handheld laser positioning weld seam according to a preferred embodiment of the present invention.

[0041] Figure 6This is a cross-sectional schematic diagram of the weld seam of a handheld laser positioning weld combined with FCAW capping according to a preferred embodiment of the present invention.

[0042] Figure 7 This is a schematic diagram of the weld structure of a handheld laser positioning welder with FCAW cover welder according to a preferred embodiment of the present invention.

[0043] Figure 8 This is a schematic diagram of the weld structure of an FCAW tack weld and an FCAW cap weld according to a preferred embodiment of the present invention.

[0044] Explanation of reference numerals in the attached figures

[0045] 1. Tack weld; 2. Cover weld; 3. Vertically placed steel plate; 4. Horizontally placed steel plate; 5. Laser welding gun. Detailed Implementation

[0046] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0047] like Figure 1 As shown, this embodiment provides a construction method for welding T-joints. The construction method includes the following steps: S1: Install the hull structure steel plate in the form of a T-joint; S2: Perform pre-welding preparation treatment on the hull structure steel plate; S3: Use a laser welding gun 5 to perform tack welding on the joint of the hull structure steel plate; S4: Use flux-cored gas shielded welding to perform cover welding on the weld 1 of the tack weld.

[0048] In this embodiment, after completing the pre-welding preparations for the T-corner joint, a laser welding torch 5 is used to precisely position the root. Leveraging the advantages of laser-positioned welding—micro-weld points, narrow hot zones, and low heat input—it effectively avoids the interference of traditional weld point protrusions on the subsequent FCAW (Fluid-cored Wire Gas Shielded Welding) capping weld weld formation, and completely eliminates the need for grinding. Combined with gas-shielded welding capping, this process significantly reduces the negative impact of welding heat input on the base material while effectively ensuring the strength and appearance of the final weld, thereby greatly improving welding quality and overall work efficiency.

[0049] Specifically, such as Figure 1As shown, in this embodiment, S2 further includes preheating and dehumidifying the hull structure steel plate. The diameter of the welding wire in the laser welding gun 5 ranges from 1.2 to 1.6 mm; in this embodiment, the diameter of the welding wire in the laser welding gun 5 is 1.2 mm. The welding wire used in the gas-shielded welding gun of S4 is a flux-cored wire, and the diameter of the flux-cored wire ranges from 1.2 to 1.6 mm; in this embodiment, the diameter of the flux-cored wire used in the gas-shielded welding gun of S4 is 1.2 mm. In this embodiment, the welding wire diameter is precisely matched with the energy density and molten pool size of laser welding, which not only fully ensures the complete melting of the welding wire and its uniform filling in the weld, but also effectively avoids process defects such as insufficient filling caused by excessively thin welding wire and incomplete melting caused by excessively thick welding wire.

[0050] In addition, such as Figures 1-4 As shown, S3 also includes: the laser power of the laser welding gun 5 is between 30% and 60%, the wire feeding speed is between 40 and 60 mm / min, the laser swing amplitude is between 3 and 5 mm, and the gun head oscillation frequency is between 20 and 40 Hz; in this embodiment, the laser power of the laser welding gun 5 is 50%, the wire feeding speed is 50 mm / min, the laser swing amplitude is 4 mm, and the gun head oscillation frequency is 30 Hz. Controlling the above operating data of the laser welding gun 5 ensures that the laser energy is sufficient to melt the welding wire and the base material to form a positioning weld. Since complete penetration of the joint is not required in the positioning welding stage, a lower power is sufficient to meet the positioning welding requirements, avoiding over-melting and excessive heat input caused by excessive power, and effectively controlling the weld leg size of the positioning weld. The angle between the laser welding gun 5 and the vertically placed steel plate 3 during the movement (e.g., the angle between the laser welding gun 5 and the vertically placed steel plate 3) is... Figure 4 The angle α is shown in the figure. The angle range is 40°~50°, and the included angle between the included angle and the horizontally placed steel plate 4 is shown in the figure. Figure 4 The angle β (as shown) ranges from 70° to 80°. Specifically, in this embodiment, the angle between the laser welding torch 5 and the vertically placed steel plate 3 during movement is 45°, and the angle with the horizontally placed steel plate 4 is 75°. This embodiment strictly limits the angle between the laser welding torch 5 and the horizontal steel plate to between 70° and 80°, so that the laser beam is projected onto the upper surface of the horizontal plate at a nearly vertical angle, achieving ideal penetration depth under low heat input conditions. At the same time, combined with the angle setting of the welding torch and the vertical steel plate at 40° to 50°, the comprehensive synergistic optimization of the incident angles in two directions is achieved, thereby effectively ensuring the fusion quality and uniformity of the forming in both sides of the T-shaped corner joint. The laser welding torch 5 injects argon gas into the weld, with an argon gas flow rate of 15 to 20 L / min. In this application, the gas flow rate is 17 L / min.

[0051] In other embodiments, the angle between the laser welding gun 5 and the horizontal and vertical steel plates can be other values. The laser power, wire feed speed, and laser swing amplitude can all be adaptively adjusted according to the actual welding object and construction needs, which will not be elaborated here.

[0052] In addition, such as Figures 1-4 As shown in Figure S4, the gas shielded welding torch is suitable for FCAW (gas-shielded flux-cored wire welding). The gas used in the gas shielded welding torch is carbon dioxide, with a flow rate of 15-25 L / min. Specifically, in this embodiment, the carbon dioxide flow rate is 17 L / min. The moving speed of the gas shielded welding torch is 270-370 mm / min, and the moving speed is 300 mm / min. The current range of the gas shielded welding torch is 210-220 A, and the welding voltage range is 24-25 V. This embodiment uses a current of 220 A and a voltage of 24 V. Within this welding speed range, the flowability of the weld pool and the heat input control of the gas shielded welding achieve an ideal balance. A moderate travel speed allows sufficient time for the molten pool metal to spread and wet, ensuring that the liquid deposited metal tightly covers and fills the tiny gaps in the tack weld, forming a dense metallurgical bond between it and the tack weld and the base metal. This effectively avoids the risk of slag inclusions or porosity caused by insufficient coverage. At the same time, a stable and uniform welding process ensures that the cover layer has a uniform thickness, a smooth and flat surface, and no appearance defects such as undercut or poor build-up, significantly improving the overall mechanical properties of the weld.

[0053] In other embodiments, the gas flow rate, torch moving speed, and current and voltage values ​​of the gas shielded welding torch can be adaptively adjusted according to actual construction needs, which will not be elaborated here.

[0054] like Figure 5 As shown, Figure 5 This is a cross-sectional view of the weld seam in a handheld laser positioning weld. This embodiment uses handheld laser welding for positioning welds, resulting in a small weld seam size. Figure 6 As shown, Figure 6 This is a weld cross-section diagram showing the weld seam after FCAW (Front-Cut Aperture Welding) is used for locating welding with handheld laser welding. This ensures that the FCAW capping operation is largely unaffected, which helps improve the forming quality and structural strength of the capping weld.

[0055] like Figures 7-8 As shown, Figure 7 This image shows the weld appearance after FCAW cap welding following tack welding with a handheld laser welding gun. Figure 8The image shows the weld appearance after FCAW tack welding and FCAW cap welding. As can be seen, tack welding using a handheld laser welding gun results in a smoother and more aesthetically pleasing weld compared to direct FCAW tack welding. The former requires no grinding, while the latter necessitates grinding; otherwise, the weld will bulge noticeably, affecting the appearance of the sheet metal. Furthermore, handheld laser welding consumes less welding material and produces less welding fumes, making it more environmentally friendly.

[0056] like Figure 2 As shown, this embodiment also provides a laser welding torch 5, which is applied in the above-mentioned construction method for welding T-joints. The laser welding torch 5 includes a welding torch body and a wire feed tube, and the wire feed tube is hinged to the welding torch body through a double-link structure. In actual welding operations, the laser welding torch 5 is first used for positioning welding, controlling the welding torch to form an acute angle with the horizontal steel plate, and the positioning welding is completed in accordance with the above-mentioned welding parameters; then, a carbon dioxide gas shielded welding torch is used to perform capping welding on the positioning weld to obtain a complete weld formation.

[0057] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A construction method for welding T-joints, characterized in that, The construction method includes the following steps: S1: Install the hull structure steel plates using T-shaped corner joints; S2: Perform pre-welding preparation treatment on the hull structure steel plates; S3: Use a laser welding gun to perform positioning welding on the joints of the hull structure steel plates; S4: Use flux-cored gas shielded welding to perform cover welding on the weld seam of the tack weld.

2. The construction method for welding T-joints as described in claim 1, characterized in that, S2 also includes preheating and dehumidifying the hull structure steel plate.

3. The construction method for welding T-joints as described in claim 1, characterized in that, The diameter of the welding wire in the laser welding gun ranges from 1.2 to 1.6 mm; And / or, the diameter of the flux-cored welding wire used in the flux-cored gas shielded welding is in the range of 1.2~1.6mm.

4. The construction method for welding T-joints as described in claim 1, characterized in that, The S3 also includes a laser power of 30% to 60% for the laser welding gun.

5. The construction method for welding T-joints as described in claim 1, characterized in that, The S3 further includes a laser welding gun with a wire feeding speed range of 40~60mm / min.

6. The construction method for welding T-joints as described in claim 1, characterized in that, The S3 also includes that the laser swing range of the laser welding gun is 3~5mm; And / or, S3 further includes that the oscillation frequency range of the laser welding gun head is 20~40Hz.

7. The construction method for welding T-joints as described in claim 1, characterized in that, The S3 further includes that the angle between the laser welding gun and the vertically placed steel plate during the movement is in the range of 40°~50°. And / or, S3 further includes that the angle between the laser welding gun and the horizontally placed steel plate during the movement is in the range of 70°~80°; And / or, S3 further includes the laser welding gun spraying gas into the weld seam during the welding process, the gas being argon, and the argon gas flow rate being 15~20L / min.

8. The construction method for welding T-joints as described in claim 1, characterized in that, The gas shielded welding torch used in S4 uses carbon dioxide as the gas, with a gas flow rate of 15~25L / min.

9. The construction method for welding T-joints as described in claim 1, characterized in that, In step S4, the moving speed of the gas shielded welding torch is 270~370 mm / min.

10. A laser welding torch, characterized in that, The laser welding torch is used in the construction method for welding T-joints as described in any one of claims 1-9. The laser welding torch includes a welding torch body and a wire feed tube, and the wire feed tube is hinged to the welding torch body through a double-link structure.

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