An ultrasonic agitation narrow gap welding system and method

Abstract

The application discloses an ultrasonic stirring narrow-gap welding system and a welding method. The ultrasonic stirring narrow-gap welding system comprises a welding machine power supply, a wire feeder, a narrow-gap welding torch and an ultrasonic stirring subsystem. The welding wire is sent into the narrow gap by the narrow-gap welding torch arranged above the groove to generate an arc for welding. The ultrasonic stirring subsystem comprises a stirrer and an ultrasonic device. The stirring rod is connected to the ultrasonic device and is inserted into the molten pool at a preset angle with the welding wire to perform stirring, thereby realizing the ultrasonic stirring narrow-gap welding mode. In the welding method, the stirring rod is inserted into the molten pool to perform stirring during the welding process, so that the arc heat is effectively transmitted to the sidewall. Meanwhile, the welding molten pool is stirred by ultrasonic agitation. On the basis of the original mechanical stirring, the effect of grain refinement is greatly strengthened, the finger-shaped penetration at the bottom of the weld is avoided, the sidewall cladding efficiency is improved, the joint organization of the narrow-gap welding is homogenized, and the strength and toughness of the welding joint are improved.

Description

Technical Field

[0001] This invention relates to the field of narrow gap welding, and in particular to an ultrasonic stirring narrow gap welding system and welding method. Background Technology

[0002] Narrow-gap GMAW has high deposition efficiency and does not require interpass slag removal. It has a wide range of heat input adjustment. Under conditions where no special techniques such as preheating before welding, interpass temperature control, or post-weld heat treatment are required, the overheating embrittlement and weakening of the weld joint are greatly reduced. Its lower heat input is very beneficial for softening the welding HAZ and helps to improve the load-bearing capacity of the weld joint and improve the dimensional accuracy of the weldment.

[0003] However, because the arc is almost parallel to the bevel sidewall in narrow-gap welding, the arc cannot directly heat the sidewall under lower heat input, easily leading to sidewall incomplete fusion defects, which seriously affects the service safety of large high-strength steel structures. To improve the welding efficiency of narrow-gap GMAW welding while maintaining its advantages of good weld formation and high welding quality, many efficient welding methods have emerged. For example, a strong mechanical stirring method for narrow-gap GMAW weld pool welding can improve sidewall fusion quality. However, this technique has the following drawbacks: the rotational stirring force generated during mechanical stirring causes uneven temperature distribution within the weld pool, resulting in high surface stress, difficulty in controlling the welding process, difficulty in achieving welding precision requirements, and uneven weld microstructure. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide an ultrasonic stirring narrow gap welding system and welding method that solves the problems of uneven weld structure, severe weld porosity, and insufficient sidewall fusion in narrow gap arc welding, thereby achieving uniform weld structure, improving welding efficiency, and realizing high-efficiency and high-quality narrow gap arc welding.

[0005] The technical solution of the present invention is as follows:

[0006] An ultrasonic stirring narrow gap welding system includes a welding machine power supply, a wire feeder, and a narrow gap welding torch. The system further includes an ultrasonic stirring subsystem, comprising an ultrasonic device and a stirrer. The ultrasonic device includes an ultrasonic vibration power supply, a transducer, an amplitude transformer, and a converter connected in sequence. The converter is fixed to the upper part of the stirrer. The narrow gap welding torch is vertically positioned above the U-shaped bevel of the workpiece to be welded. Welding wire from the wire feeder is fed into the bevel through the narrow gap welding torch. The positive terminal of the welding machine power supply is connected to the welding wire in the narrow gap welding torch, and the negative terminal is connected to the workpiece to be welded. The stirrer is positioned on one side of the narrow gap welding torch, with its stirring rod inserted into the bevel at an angle relative to the welding wire. During operation, the end of the stirring rod can extend into the molten pool within the bevel and stir the weld.

[0007] Furthermore, the angle of inclination of the stirring rod relative to the welding wire is 15° to 60°, and the horizontal distance between the end of the stirring rod and the end of the welding wire is 10mm.

[0008] Furthermore, the distance from the end of the welding wire to the bevel surface of the workpiece is 5–8 mm.

[0009] Furthermore, the stirring end of the stirring rod is a propeller type, a cylindrical type, or a rotary wheel type.

[0010] Furthermore, the stirring rod is made of tungsten, vanadium, or ceramic, all of which are high-temperature resistant materials. This prevents the electric arc temperature from being too high and melting the rod, thus preventing impurities from appearing in the weld.

[0011] Ideally, the stirring rod should rotate at a speed of 0–1200 rpm, and the ultrasonic vibration power supply should have an ultrasonic vibration frequency of 30–50 kHz.

[0012] Ideally, the welding current of the welding machine power supply should be 50–400A, and the gas flow rate inside the narrow-gap welding torch should be 30L / min.

[0013] The welding method based on the ultrasonic stirring narrow gap welding system includes the following steps:

[0014] Step 1: Select the welding current mode as DC reverse polarity;

[0015] Step 2: Take the workpiece to be welded, grind or clean its surface, fix the ground or cleaned workpiece on the welding fixture of the welding platform, make a U-shaped bevel on the workpiece to be welded, press the four corners of the workpiece to be welded, and turn on the water, electricity and gas.

[0016] Step 3: Turn on the ultrasonic stirrer and adjust its position so that the stirring rod can be tilted and fixed inside the bevel.

[0017] Step 4: Set the stirring parameters and welding power parameters; the stirring parameters include stirring speed, stirring excitation voltage, stirring rod radius and ultrasonic frequency, and install the stirring rod of the selected radius type on the stirrer; the welding parameters include welding current, welding speed, nozzle height and shielding gas flow rate, wherein the welding speed is controlled by controlling the moving speed of the welding platform;

[0018] Step 5: Adjust the position of the narrow gap welding torch so that the welding wire is in the center of the bevel. After setting other parameters, start the joint control switch, start the welding platform, start welding, start the narrow gap welding torch to generate a welding arc, and feed the welding wire to the arc by the wire feeder to start welding. A molten pool is formed on the surface of the workpiece to be welded.

[0019] Step 6: Readjust the stirrer to ensure the stirring rod is inserted into the molten pool to the required depth, and adjust the angle between the stirring rod and the welding wire. Arrange the narrow-gap welding torch and the stirring rod in a staggered manner along the welding direction. Adjust the rotation speed of the stirring rod and the ultrasonic frequency of the ultrasonic device. The generated ultrasonic waves are transmitted to the molten pool through the stirring rod. At the same time, the stirring rod begins to stir the molten pool.

[0020] Step 7: After the entire weld seam is completed, turn off all power supplies, allow it to air cool to room temperature, remove the workpiece to be welded, wipe the surface of the workpiece clean, and the welding is complete.

[0021] Ideally, the welding speed is 140–400 mm / min, the radius of the stirring rod is 1.5–2 mm, and the stirring excitation voltage is 5 VDC.

[0022] Ideally, the stirring rod should be inserted into the molten pool to a depth of 1–3 mm.

[0023] This invention connects a stirring rod to an ultrasonic device, and then inserts the stirring rod into the molten pool for stirring, thereby realizing a narrow-gap ultrasonic stirring welding method, which simultaneously increases the ultrasonic stirring and mechanical stirring effects in the welding system.

[0024] The ultrasonic stirring subsystem performs two main functions. First, it mechanically stirs the molten pool, creating vortices that accelerate heat exchange and effectively transfer the arc heat to the sidewalls. This results in a more uniform temperature distribution, increased sidewall penetration, prevention of finger-like penetration at the weld bottom, reduced cracking tendency, and improved weld quality. The thorough stirring also causes gases to escape from the molten metal, reducing porosity and ensuring a more uniform distribution of beneficial elements within the pool. Second, the ultrasonic stirring significantly enhances grain refinement compared to mechanical stirring, preventing finger-like penetration at the weld bottom, improving sidewall cladding efficiency, achieving homogenized microstructure in narrow-gap weld joints, and ultimately increasing the strength and toughness of the weld joint.

[0025] Compared with traditional narrow-gap arc welding, this invention essentially does not change the heat input of the traditional narrow-gap arc welding process, thus effectively avoiding the adverse effects of additional heat input on grain refinement. Meanwhile, the ultrasonic mechanical stirring method has advantages such as simple equipment, low cost, and convenient operation. It can achieve a high shear rate and strong adaptability. It can achieve high efficiency and low cost in welding production and processing, and has broad prospects for industrial application. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0027] Figure 2 This is a flowchart of the working method of the present invention;

[0028] Figure 3(a) is a metallographic diagram of an unstirred narrow-gap welded workpiece, and (b) is a metallographic diagram of a narrow-gap welded workpiece welded by the welding method described in this invention.

[0029] In the diagram: 1. Welding machine power supply, 2. Wire feeder, 21. Welding wire, 3. Narrow gap welding torch, 31. Stirring rod, 4. Ultrasonic vibration power supply for signal connection, 5. Transducer, 6. Amplifier, 61. Molten pool, 7. Converter, 8. Stirrer, 9. Stirrer power supply, 10. Workpiece to be welded. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] The ultrasonic stirring narrow gap welding system of the present invention, such as Figure 1 As shown, the system includes a welding power supply 1, a wire feeder 2, a narrow gap welding torch 3, and an ultrasonic stirring subsystem. The ultrasonic stirring subsystem includes an ultrasonic device and a stirrer 8. The ultrasonic device includes an ultrasonic vibration power supply 4, a transducer 5, an amplitude converter 6, and a converter 7 connected in sequence. The converter 7 is fixed to the upper part of the stirrer 8. A U-shaped groove is provided on the workpiece 10 to be welded. The narrow gap welding torch 3 is vertically arranged on the U-shaped groove. The welding wire 21 in the wire feeder 2 is fed into the U-shaped groove through the narrow gap welding torch 3. The positive terminal of the welding power supply 1 is connected to the welding wire 21 in the narrow gap welding torch 3, and the negative terminal is connected to the workpiece 10 to be welded. The stirrer 8 is arranged on one side of the narrow gap welding torch 3 and is connected to the stirrer power supply (9). The stirring rod 31 of the stirrer 8 is inserted into the U-shaped groove at an angle relative to the welding wire 21. During operation, the end of the stirring rod 31 extends into the molten pool 61 in the U-shaped groove and stirs.

[0032] The tilt angle of the stirring rod 31 relative to the welding wire 21 is 15°–60°, and the horizontal distance between the end of the stirring rod 31 and the end of the welding wire 21 is 10 mm; the distance from the end of the welding wire 21 to the bevel surface of the workpiece 10 to be welded is 5–8 mm. The stirring end of the stirring rod 31 is a propeller type, a cylindrical type, or a rotary wheel type; the material of the stirring rod 31 is a high-temperature resistant material, such as tungsten, vanadium, or ceramic. The rotational speed of the stirring rod 31 is 0–1200 rpm, and the ultrasonic vibration frequency of the ultrasonic vibration power supply 4 is 30–50 kHz. The welding current of the welding machine power supply 1 is 50–400 A, and the gas flow rate inside the narrow gap welding torch 3 is 30 L / min.

[0033] The welding method of the above-mentioned ultrasonic stirring narrow gap welding system, such as Figure 2 As shown, it includes the following steps:

[0034] Step 1: Select the welding current mode as DC reverse polarity, connect the positive terminal of the welding machine power supply 1 to the welding wire 21 in the narrow gap welding torch 3, and connect the negative terminal to the workpiece 10.

[0035] Step 2: Take the workpiece 10 to be welded, grind or clean its surface, fix the ground or cleaned workpiece 10 on the welding fixture of the welding platform, make a U-shaped bevel on the workpiece 10 to be welded, press the four corners of the workpiece 10 to be welded, and turn on the water, electricity and gas; connect the welding wire, welding power source and arc ignition control line in the narrow gap welding torch according to the connection method of the welding system described above.

[0036] Step 3: Turn on the ultrasonic vibration power supply 4 and the stirrer power supply 9, and adjust the position of the stirrer 8 so that its stirring rod can be tilted and fixed in the U-shaped bevel.

[0037] Step 4: Set the ultrasonic and stirring parameters and welding power parameters; the ultrasonic and stirring parameters include stirring speed, stirring excitation voltage, stirring rod radius, and ultrasonic frequency. The stirring rod of the selected model is installed at an angle on the stirrer, the stirring excitation voltage is 5VDS, and the stirring rod radius is 1.5-2mm; the welding parameters include welding current, welding speed, nozzle height, and shielding gas flow rate. The welding speed is controlled by controlling the moving speed of the welding platform, and the welding speed is 140-400mm / min.

[0038] Step 5: Adjust the position of the narrow gap welding torch so that the welding wire is in the center of the bevel, and the distance from the end of the welding wire (21) to the U-shaped bevel surface of the workpiece 10 to be welded is 5-8 mm. Start the joint control switch, start the welding platform, start welding, start the narrow gap welding torch to generate a welding arc, feed the welding wire to the arc by the wire feeder and start welding, and a molten pool is formed on the surface of the workpiece 10 to be welded.

[0039] Step 6: Gradually insert the stirring rod 31 into the molten pool 61 by 1-3 mm. Adjust the angle between the stirring rod 31 and the welding wire 21 to 15°-60°, so that the narrow-gap welding torch 3 and the stirring rod 31 are staggered back and forth along the welding direction, and the horizontal distance between the end of the stirring rod 31 and the end of the welding wire 21 is 10 mm. Adjust the rotation speed of the stirring rod 31 and the ultrasonic frequency of the ultrasonic vibration power supply 4. The generated ultrasonic waves are transmitted to the molten pool 61 through the stirring rod 31, and at the same time, the stirring rod 31 begins to stir the molten pool 61.

[0040] Step 7: After the entire weld seam is completed, turn off the welding system, ultrasonic vibration power supply 4 and stirrer power supply 9, air cool to room temperature, remove the workpiece 10 to be welded, wipe the surface of the workpiece 10 clean, and the welding is completed.

[0041] Figure 3 (a) and (b) are metallographic images of narrow-gap welded workpieces without stirring and with stirring assistance, respectively. By comparison, the welding method described in this invention can effectively reduce bubbles, refine grains, and produce a uniform microstructure at the weld joint.

[0042] In specific embodiments, in order to protect the heating zone during the welding process, ensure the stability of the welding, and prevent the weld from deforming due to air entering the weld, the present invention fills the protective gas area with an inert protective gas, such as argon. The present invention does not limit or fix this and can select according to the actual situation.

[0043] This invention has wide applicability and is applicable to the welding of metal materials such as steel. It is applicable not only to consumable electrode arc welding but also to non-consumable electrode arc welding.

Claims

1. An ultrasonic stirring narrow gap welding system, comprising a welding power supply (1), a wire feeder (2), and a narrow gap welding torch (3), characterized in that: It also includes an ultrasonic stirring subsystem, which includes an ultrasonic device and a stirrer (8). The ultrasonic device includes an ultrasonic vibration power supply (4), a transducer (5), an amplitude transformer (6), and a converter (7) connected in sequence. The converter (7) is fixed to the upper part of the stirrer (8). The narrow gap welding torch (3) is vertically set above the U-shaped groove of the workpiece (10) to be welded. The welding wire (21) in the wire feeder (2) is fed into the U-shaped groove through the narrow gap welding torch (3). The positive terminal of the welding power supply (1) is connected to the welding wire (21) in the narrow gap welding torch (3), and the negative terminal is connected to the workpiece (10) to be welded. The stirrer (8) is set on one side of the narrow gap welding torch (3) and connected to the stirrer power supply (9). The stirring rod (31) of the stirrer (8) is inserted into the U-shaped groove at an angle relative to the welding wire (21). When working, the end of the stirring rod (31) can extend into the molten pool (61) in the groove and stir. The angle of inclination of the stirring rod (31) relative to the welding wire (21) is 15° to 60°, and the horizontal distance between the end of the stirring rod (31) and the end of the welding wire (21) is 10 mm; the material of the stirring rod (31) is tungsten, vanadium or ceramic; The welding method of the ultrasonic stirring narrow gap welding system includes the following steps: Step 1: Select the welding current mode as DC reverse polarity, connect the positive terminal of the welding machine power supply (1) to the welding wire (21) in the narrow gap welding torch (3), and connect the negative terminal to the workpiece (10); Step 2: Take the workpiece to be welded (10), grind or clean its surface, fix the ground or cleaned workpiece to be welded (10) on the welding fixture of the welding platform, make a U-shaped bevel on the workpiece to be welded (10), press the four corners of the workpiece to be welded (10) tightly, and turn on the water, electricity and gas. Step 3: Install the stirring rod (31) on the stirrer, turn on the ultrasonic vibration power supply (4) and the stirrer power supply (9), and adjust the position of the stirrer (8) so that the stirring rod (31) can be tilted and fixed in the bevel. Step 4: Set the ultrasonic and stirring parameters and the welding power parameters; the ultrasonic and stirring parameters include stirring speed, stirring excitation voltage, stirring rod radius and ultrasonic frequency; the welding parameters include welding current, welding speed, nozzle height and shielding gas flow rate, wherein the welding speed is controlled by controlling the moving speed of the welding platform; Step 5: Adjust the position of the narrow gap welding torch (3) so that the welding wire (21) is vertically positioned at the center of the U-shaped groove. Start the joint control switch, start the welding platform, and begin welding. Start the narrow gap welding torch (3) to generate a welding arc. The wire feeder (2) feeds the welding wire (21) to the arc and begins welding. A molten pool (61) is formed on the surface of the workpiece (10) to be welded. Step 6: Adjust the stirrer (8) again to ensure that the depth of the stirring rod (31) into the molten pool (61) meets the requirements, and adjust the angle between the stirring rod (31) and the welding wire (21) so that the narrow gap welding torch (3) and the stirring rod (31) are staggered back and forth along the welding direction. Adjust the rotation speed of the stirring rod (31) and the ultrasonic frequency of the ultrasonic device. The generated ultrasonic waves are transmitted to the molten pool (61) through the stirring rod (31). At the same time, the stirring rod begins to stir the molten pool. Step 7: After the entire weld seam is completed, turn off all power supplies, allow it to air cool to room temperature, remove the workpiece (10) to be welded, wipe the surface of the workpiece (10) clean, and the welding is complete.

2. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The distance from the end of the welding wire (21) to the U-shaped groove surface of the workpiece (10) to be welded is 5 to 8 mm.

3. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The stirring end of the stirring rod (31) is a propeller type, a cylinder type, or a rotary wheel type.

4. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The stirring rod (31) rotates at a speed of 0 to 1200 rpm, and the ultrasonic vibration frequency of the ultrasonic vibration power supply (4) is 30 to 50 kHz.

5. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The welding current of the welding machine power supply (1) is 50-400A, and the gas flow rate in the narrow gap welding torch (3) is 30L / min.

6. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The welding speed is 140-400 mm / min, the radius of the stirring rod is 1.5-2 mm, and the stirring excitation voltage is 5VDC.

7. The ultrasonic stirring narrow gap welding system according to claim 1, characterized in that: The stirring rod should be inserted into the molten pool to a depth of 1–3 mm.

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