Handheld cold wire assisted swing laser-electric arc hybrid welding method

Abstract

The invention relates to the technical field of laser-electric arc hybrid welding, in particular to a handheld cold wire auxiliary swing laser-electric arc hybrid welding method which comprises the following steps: preparing before welding; setting welding parameters; and a cold wire auxiliary welding step. The cold wire auxiliary welding specifically comprises the steps that under the argon atmosphere, a handheld swing laser-electric arc composite welding gun is used, a cold wire is placed at the position to be welded, and the cold wire is located between laser and an electric arc welding wire for welding. Cold wires are used for assisting in welding, the auxiliary cold wires are inserted into the molten pool in the welding process, molten pool liquid metal is promoted to flow, molten pool air hole defects are discharged, and the aluminum alloy welding air hole problem is greatly solved. According to cold wire auxiliary welding, heat lost by laser and electric arc is utilized for melting an auxiliary welding wire, the energy loss is effectively reduced, meanwhile, the energy utilization rate is greatly improved, and under the same heat input, the higher metal melting amount is achieved, and the welding material cladding efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser-arc hybrid welding, in particular to a handheld cold wire assisted swinging laser-arc hybrid welding method. Background Art

[0002] At present, the automobile manufacturing industry is increasingly increasing its efforts in energy conservation and environmental protection, and reducing the weight of automobiles to achieve lightweight is one of the important means. Using aluminum alloy materials instead of traditional steel materials is a major weight reduction method for major automobile manufacturers, especially in the field of new energy vehicles. The weight of the car seriously affects the cruising range. Compared with traditional fuel vehicles, new energy vehicles are more urgently in need of lightweight development. At present, aluminum alloy materials have been basically used in automobile chassis, frames, wheels, anti-collision beams, battery shells, etc., which is bound to involve the welding process of aluminum alloys. However, aluminum alloys are prone to defects such as pores during the welding process, which reduces the effective cross-sectional area of ​​the weld, causes stress concentration, and reduces the strength of the weld.

[0003] Traditional aluminum alloy welding methods include laser welding, MIG welding (Melt Inert Gas Welding), TIG welding (Tungsten Inert Gas Welding), laser-arc hybrid welding, etc. When single laser welding aluminum alloy, there is a problem of weld collapse due to the use of no filler wire, and the deep keyhole also leads to poor fluidity of the molten pool, which is easy to be unstable, resulting in gas cannot be discharged and porosity defects. When ordinary arc welding is used to weld aluminum alloy, there is a problem of small penetration depth, and it cannot meet the process requirements when welding thick-walled structures of car bodies. Laser-arc hybrid welding has the synergistic effect of laser and arc, and has the advantages of laser and arc, and has good stability. However, in the cast aluminum alloy material of the welded car body, there is still a problem of porosity defects caused by the molten pool gas not being discharged in time, and the heat loss of hybrid welding is serious, and there is a problem of low energy utilization.

[0004] In addition, during daily use of an automobile, the body structure is often damaged due to some reasons, such as collisions, etc. This will inevitably involve the welding repair of the aluminum alloy structure, and the welding repair will involve the selection of repair methods and repair processes. For the welding repair method, the structural damage of equipment such as automobiles often has the characteristics of special damage positions and irregular damage morphologies, which puts higher requirements on structural repair. Automatic repair cannot achieve the repair of defects with complex shapes and narrow spaces, while the repair with a hand-held welding torch has the advantages of light equipment and strong space adaptability, and is an ideal welding repair method for repairing complex structures and narrow spaces. For the repair process, welding repair not only requires a high welding efficiency, but also needs to change the original structural organization as little as possible. When traditional arc welding and laser-arc welding repair larger defects, due to insufficient wire filling amount, it is impossible to achieve one-time repair forming, and the wire feeding speed of the welding machine is often related to the current and voltage. Increasing the wire feeding amount will lead to a large heat input, thus changing the tissue properties of the original structure. If multiple repairs are used, not only will the workload be increased, but the work efficiency will also be reduced, and due to multiple weldings, the tissue properties of the original structure will also be changed. When using laser wire filling welding for repair, due to the low absorption rate of aluminum alloy to laser, when laser wire filling repairs larger defects, the laser power will be greatly increased to melt the welding wire, resulting in a large energy loss and wasting resources.

[0005] Existing patents such as CN106475684A, a laser-arc hybrid welding method for reducing aluminum alloy welding pores, and CN105904117A, a forged and twisted gynostemma pentaphyllum welding wire, etc. provide an idea for solving the above problems, that is, by using a welding wire with a special structure to achieve a stirring effect on the fluid in the molten pool, helping the gas in the molten metal to overflow, inhibiting the generation of welding pores, thereby reducing weld defects and improving welding quality, etc. However, the above patents obviously have the problem of high cost of the special welding wire, which is not conducive to practical popularization and application. In addition, some technologies also use agents to inhibit the generation of pores, but ultimately due to defects such as cumbersome processes and easy inclusion, it is still difficult to popularize and apply.

[0006] It can be seen that there is an urgent need for a welding method with higher flexibility, stronger welding stability, higher energy utilization rate, and more effective control of welding defects. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a hand-held cold wire assisted oscillating laser-arc hybrid welding method.

[0008] The purpose of the present invention is achieved through the following technical solutions: A hand-held cold wire assisted oscillating laser-arc hybrid welding method, comprising the following steps:

[0009] S1. Preparation before welding: Pretreat the area to be welded on the surface of the specimen, and then assemble and fix the workpiece to be welded;

[0010] S2. Set welding parameters;

[0011] S3. Cold wire assisted welding: In an argon gas atmosphere, use a handheld oscillating laser-arc hybrid welding torch. Place the cold wire at the position to be welded and between the laser and the arc welding wire. Press and hold the welding torch switch, and then move the welding torch along the position to be welded. During this period, keep the cold wire at the position to be welded and between the laser and the arc welding wire. The wire feeding speed of the cold wire ranges from 1 m / min to 6 m / min.

[0012] Further, in step S1, the steps of the pretreatment include: successively grinding, cleaning, and drying the surface of the specimen.

[0013] Further, in step S1, the joint formed at the position to be welded of the workpiece to be welded is a butt joint, a T-joint, a lap joint, or a surfacing joint.

[0014] Further, in step S2, the welding parameters include laser parameters, specifically including a laser power of 1200 w to 3000 w, a swing amplitude of 1 mm to 3 mm, a swing frequency of 1 to 200 Hz, a swing mode of left-right swing, an incident angle of 0° to 30°, and a defocus amount of 0 mm.

[0015] Further, in step S2, the welding parameters include arc parameters, specifically including a welding current of 150 A to 230 A, a welding voltage of 20.1 V to 24.1 V, a wire dry elongation of 16 mm to 18 mm, an arc welding wire feeding speed of 7.5 m / min to 11.5 m / min, a distance between the arc welding wire and the laser of 3 mm to 5 mm, and a welding torch angle of 0° to 30°.

[0016] Further, in step S3, the gas flow rate of the argon is 25 to 30 L / min.

[0017] Further, in step S3, a wire feeding nozzle is provided between the laser emitting head and the arc welding torch head of the handheld oscillating laser-arc hybrid welding torch. The wire feeding nozzle is connected to an automatic wire feeder. Through the setting of the wire feeding nozzle, the cold wire is continuously placed at the position to be welded and between the laser and the arc welding wire, and the deflection angle of the cold wire is 0° to 15°.

[0018] Further, in step S3, the handheld oscillating laser-arc hybrid welding torch includes a handheld part, a laser emitting head, an arc welding torch, and an auxiliary wire feeder. They are combined into one by a fixture and connected to the control switch of the handheld part to realize the synchronous connection of the switch to the system.

[0019] Further, in step S3, the welding speed is controlled manually, and the speed range is 0.5 m / min to 5 m / min.

[0020] The beneficial effects of the present invention are as follows: By placing the cold wire at the position to be welded and between the laser and the arc welding wire, and using the cold wire to assist in welding, during the welding process, the cold wire is inserted into the molten pool, promoting the flow of the molten metal in the molten pool, enabling the discharge of the porosity defects in the molten pool, and significantly improving the porosity problem in aluminum alloy welding. The cold wire assisted welding utilizes the heat lost by the laser and the arc to melt the auxiliary welding wire, effectively reducing the energy loss while significantly improving the energy utilization rate. Under the same heat input, there is a higher metal melting amount, and the cladding efficiency of the welding material is significantly improved. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the structure of the welding torch;

[0022] Figure 2 It is a schematic diagram of the molten pool state;

[0023] Figure 3 It is a comparison diagram of the welding effect;

[0024] In the figure, 1 - material to be welded; 2 - arc welding torch head; 3 - wire feeding nozzle; 4 - laser emitting head; 5 - molten pool; 6 - backing plate; 7 - handheld part; 8 - switch; 9 - arc welding wire; 10 - molten droplet; 11 - weld seam; 12 - cold wire; 13 - laser; 14 - molten metal. Detailed Description of the Embodiment

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0026] Embodiment 1

[0027] Referring to Figure 1 , the present invention provides a laser-arc hybrid welding torch for use in a handheld cold wire assisted oscillating laser-arc hybrid welding method, including a laser-arc hybrid welding torch. The feature is that a wire feeding nozzle 3 is arranged between the laser emitting head 4 and the arc welding torch head 2 of the laser-arc hybrid welding torch. During the welding process, the wire feeding nozzle 3 can continuously feed out the cold wire 12. In addition, the present invention can also directly use a traditional laser-arc hybrid welding torch, and continuously place the cold wire at the position to be welded and between the laser 13 and the arc welding wire 9 in a handheld manner at a certain wire feeding speed.

[0028] Figure 2It is a schematic diagram of a molten pool. The arc welding torch and the laser have a certain deflection angle, ranging from 0° to 30°. There is a certain space between the arc welding torch and the laser, enabling the auxiliary welding wire (cold wire) to be located between the laser and the arc. The auxiliary welding wire also has a certain deflection angle, ranging from 0° to 15°.

[0029] The principle of the present invention is as follows: Referring to Figure 2 , the addition of the cold wire 12 will change the stress state inside the molten pool 5. During the process of feeding into the molten pool 5, the cold wire 12 occupies a certain space, squeezing the liquid molten metal 14 in the molten pool 5 and causing it to flow. When the cold wire 12 is added to the relatively high-temperature molten pool 5, it will cause thermal convection. The temperature of the cold wire 12 is much lower than that of the molten pool 5. After being inserted into the molten pool 5, the surrounding high-temperature liquid metal will quickly transfer heat to the cold wire, resulting in the temperature of this part of the metal decreasing and the density increasing, thus sinking.

[0030] Example 2

[0031] The handheld cold wire-assisted oscillating laser-arc hybrid welding method is specifically carried out according to the following process steps:

[0032] (1) Pretreatment of the workpiece to be welded

[0033] In this experiment, butt welding was performed on 3-mm-thick AlSi20 aluminum alloy. The surface of the workpiece was polished with a angle grinder, and then cleaned, dried with anhydrous ethanol. The purpose was to remove the surface oxide film and prevent defects such as pores and slag inclusions during the welding process.

[0034] (2) Assembling and fixing the workpiece to be welded

[0035] The specimen to be welded was placed stably on a copper backing plate for surfacing welding, and the specimen and the copper backing plate were fixed on the workbench with a fixing fixture to prevent the specimen from deforming due to uneven temperature distribution during the welding process, which would ultimately lead to welding failure.

[0036] (3) Setting welding parameters

[0037] Welding current: 180 A, voltage: 22.6 V, wire feeding speed of the arc welding wire: 9 m / min, wire dry elongation: 16 mm, laser power: 2400 w, laser oscillation amplitude: 1 mm, oscillation shape: left-right oscillation, oscillation frequency: 120 Hz, defocus amount: 0 mm, shielding gas: 99.9% high-purity argon, flow rate: 25 L / min, wire feeding speed of the auxiliary welding wire: 3 m / min, distance between the laser and the wire: 4 mm, the auxiliary welding wire is located between the arc and the laser, welding speed: 1 m / min.

[0038] (4) Inspection before welding

[0039] Check whether the instrument setting parameters are consistent with the process book. Click the gas detection button of the welding machine and introduce high-purity argon in advance. The purpose is to detect whether the protection device is operating normally. Secondly, discharge the air in the equipment ventilation pipeline to ensure that high-purity argon is introduced during welding, prevent impurity gases from contaminating the weld, and cause defects.

[0040] (5) Welding of test plate

[0041] Wear professional welding goggles, hold the composite welding torch, align it with the position to be welded, with the laser in the front, the auxiliary welding wire in the middle, and the arc in the back. Adjust the welding angle, press and hold the switch on the hand-held part of the welding torch. After starting the arc, observe the weld position and move the welding torch along the welding direction at an appropriate speed according to the welding situation.

[0042] (6) Post-weld treatment

[0043] When welding is completed, release the switch, remove the specimen, remove the surface impurities, observe the weld, preliminarily evaluate the weld forming quality, and conduct X-ray non-destructive testing, metallographic observation, and microscopic observation on the welded joint.

[0044] The results are as follows: The weld surface has no cracks or spatter, is white, and the weld quality is good. Conduct X-ray non-destructive testing, metallographic observation, and microscopic observation on the welded joint. As Figure 3 shown in a), it can be seen that there are no cracks or inclusion defects in the joint, and there are small pores at the weld root and the upper part of the weld. The cross-sectional area of the weld is 36.34 mm 2 .

[0045] Example 3

[0046] Adjust the feeding speed of the auxiliary welding wire in Example 2 to 6 m / min, with the same experimental parameters for other parameters, and use the same welding speed.

[0047] After welding, observe the weld surface. It can be seen that the weld surface with the auxiliary welding wire feeding speed of 6 m / min has no cracks or spatter, is white, and the weld quality is good. Conduct X-ray non-destructive testing, metallographic observation, and microscopic observation on the welded joint. As Figure 3 shown in c), it can be seen that there are no cracks or inclusion defects in the joint. For the weld with the auxiliary welding wire feeding speed of 6 m / min, due to the addition of the auxiliary welding wire, the molten pool flow is promoted, so that the weld pores overflow fully, and no obvious pores appear. Only a small amount of small pores exist at the weld root and the upper part of the weld. The cross-sectional area of the weld is 42.53 mm 2 , compared with the 3 m / min wire feeding in Example 1, the cladding efficiency increases by 17.3%, and compared with the 0 m / min wire feeding, the cladding efficiency increases by 31.1%, and the cladding efficiency is greatly improved.

[0048] Comparative Example 1

[0049] Adjust the wire feeding speed of the auxiliary wire in Example 2 to 0 m / min, that is, do not use the auxiliary wire, and keep other experimental parameters the same, and use the same welding speed.

[0050] After welding, observe the weld surface. It can be seen that the weld surface without the auxiliary wire has no cracks and spatter, and is white, indicating good weld quality. Perform X-ray non-destructive testing, metallographic observation, and microscopic observation on the welded joint. As Figure 3 shown in b), it can be seen that there are no cracks and inclusion defects in the joint. However, for the weld without the auxiliary wire, due to the poor fluidity of the molten pool and the gas not having enough time to escape, obvious pores exist at the root of the weld. The cross-sectional area of the weld is 32.43 mm 2 , and the cladding efficiency is reduced by 12% compared to the wire feeding speed of 3 m / min.

[0051] Comparative Example 2

[0052] Change the wire feeding speed of the arc wire in Comparative Example 1 to 10 m / min, keep other experimental parameters the same, and use the same welding speed.

[0053] After welding, observe the weld surface. It can be seen that the weld surface without the auxiliary wire has no cracks and spatter, and is white, indicating good weld quality. Perform X-ray non-destructive testing, metallographic observation, and microscopic observation on the welded joint. As Figure 3 shown in d), it can be seen that there are no cracks and inclusion defects in the joint. However, for the weld without the auxiliary wire, due to the poor fluidity of the molten pool and the gas not having enough time to escape, obvious pores exist at the root of the weld. The cross-sectional area of the weld is 34.12 mm 2 , and the cladding efficiency is reduced by 6% compared to the wire feeding speed of 3 m / min.

[0054] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments. Instead, it can be used in various other combinations, modifications, and environments, and can be changed within the scope of the concept described herein through the above teachings or the techniques or knowledge in related fields. Any changes and variations made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A handheld cold wire assisted swing laser-arc hybrid welding method, characterized in that: The following steps are involved: S1. Preparation before welding: pre-treat the area to be welded on the surface of the sample, and then assemble and fix the parts to be welded; S2, set welding parameters; S3. Cold wire assisted welding: In an argon gas atmosphere, use a handheld oscillating laser-arc hybrid welding gun, place the cold wire at the position to be welded and between the laser and arc welding wires, press and hold the welding gun switch, and then move the welding gun along the position to be welded. During this period, keep the cold wire at the position to be welded and between the laser and arc welding wires. The wire feeding speed range of the cold wire is 1m / min to 6m / min.

2. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S1, the pretreatment step includes: polishing, cleaning and drying the surface of the specimen in sequence.

3. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S1, the joint formed at the welded portion of the welded parts is a butt joint, a T-joint, a lap joint or a cladding joint.

4. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S2, the welding parameters include laser parameters, specifically including laser power of 1200w~3000w, swing amplitude of 1mm~3mm, swing frequency of 1~200Hz, swing mode of left and right swing, incident angle of 0°~30°, and defocus amount of 0mm.

5. The handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S2, the welding parameters include arc parameters, specifically including a welding current of 150A to 230A, a welding voltage of 20.1V to 24.1V, a welding wire dry extension of 16mm to 18mm, an arc welding wire feeding speed of 7.5m / min to 11.5m / min, a distance between the arc welding wire and the laser of 3mm to 5mm, and a welding gun angle of 0° to 30°.

6. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S3, the gas flow rate of the argon gas is 25 to 30 L / min.

7. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S3, a wire feeding nozzle is arranged between the laser emission head and the arc welding gun head of the handheld oscillating laser-arc composite welding gun, and the wire feeding nozzle is connected to an automatic wire feeder. Through the setting of the wire feeding nozzle, the cold wire is continuously placed in the position to be welded and located between the laser and the arc welding wire, and the deflection angle of the cold wire is 0° to 15°.

8. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 7, characterized in that: In step S3, the handheld oscillating laser-arc hybrid welding gun includes a handheld part, a laser emission head, an arc welding gun, and an auxiliary welding wire feeder, which are combined into one by a clamp and connected to the control switch of the handheld part to achieve synchronous connection of the switch to the system.

9. A handheld cold wire assisted oscillating laser-arc hybrid welding method according to claim 1, characterized in that: In step S3, the welding speed is manually controlled in a speed range of 0.5 m / min to 5 m / min.

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