A double-sided indirect electric arc welding method

Abstract

This invention discloses a double-sided indirect arc welding method, belonging to the field of metal welding technology, suitable for welding scenarios involving single-sided welding of plates with double-sided forming, low deformation, and high efficiency. A TIG electrode is placed on the back of the plate, and a single / double-wire MIG / MAG electrode is placed on the front. The base material is not connected to a power source, and an indirect arc is formed between the two electrodes. After the root pass is completed, the front MIG / MAG welding wire fills the cover pass. This invention achieves high-speed, low-heat-input welding by controlling the bevel angle, butt joint gap, blunt edge size, and matching welding parameters, significantly reducing plate deformation. The TIG arc on the back ensures a smooth weld formation, eliminating the need for secondary grinding; the MIG / MAG arc on the front improves deposition efficiency. This method provides stable welding quality, with no defects such as incomplete penetration, and is suitable for various plates such as carbon steel, stainless steel, and aluminum alloys. It meets the needs of industrial mass production and effectively solves the problems of high heat input, poor weld formation, and low efficiency associated with traditional welding.

Description

Technical Field

[0001] This invention belongs to the field of metal welding technology, specifically relating to a double-sided indirect arc welding method, which is particularly suitable for plate welding scenarios that require single-sided welding with double-sided forming, low deformation, and high efficiency. Background Technology

[0002] In plate welding, traditional direct arc welding technology, due to the direct action of the arc on the base material, results in a large heat input, which easily leads to significant workpiece deformation, affecting the dimensional accuracy and mechanical properties of the welded parts. Simultaneously, conventional single-sided welding with double-sided forming often results in irregular back-side forming and surface roughness, requiring subsequent secondary grinding, increasing process costs and time, and reducing production efficiency. For welding medium and thick plates, tungsten inert gas (TIG) welding is mainly used for the root pass, but its welding speed is slow and efficiency is low.

[0003] Indirect arc welding refers to an arc where the arc burns independently between two welding torch electrodes, the workpiece does not participate in the conductive circuit, and heat is mainly transferred through radiation. Current indirect arc welding methods include dual-arc and multi-arc methods, with arrangements including parallel side-by-side, V-angle, front-and-back tandem, and staggered arrangements. Existing indirect arc welding technology uses a single-sided electrode arrangement, primarily to reduce heat input by ensuring the base material is not connected to the circuit, thus improving the filling groove or surfacing performance.

[0004] Existing indirect arc welding processes cannot simultaneously achieve high-quality double-sided forming, primarily because the welding torch is positioned on only one side of the sheet metal, lacking arc force directed towards the back of the sheet, resulting in insufficient penetration and making it difficult to achieve single-sided welding with double-sided forming. To address these technical shortcomings, there is an urgent need for a welding method that integrates the advantages of low heat input from indirect arc welding with the requirements of double-sided forming, achieving low heat input welding, single-sided root pass welding with double-sided forming, and high speed and efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-sided indirect arc welding method, specifically achieving the following three core objectives:

[0006] (1) By adopting indirect arc welding, the heat input during the welding process is reduced, the welding deformation of the plate is reduced, and the mechanical properties of the welded joint are improved; (2) Achieve single-sided welding and double-sided forming of the plate, especially the back side is smoothly formed by TIG electric arc, eliminating the need for subsequent secondary grinding process and reducing production costs; (3) The front side is filled with a single-wire or double-wire MIG / MAG arc, which greatly improves welding efficiency and meets the needs of industrial mass production.

[0007] Therefore, the present invention adopts the following technical solution: A double-sided indirect arc welding method is disclosed. During welding, an indirect arc welding mode is employed. A tungsten inert gas (TIG) electrode is placed on the back side of the plate, while a single-wire or dual-wire gas metal arc welding (MIG / MAG) electrode is placed on the front side. The base material is not connected to the welding power source. An indirect arc is formed between the front-side MIG / MAG electrode and the back-side TIG electrode. The root pass is completed using this indirect arc, and the fill pass is completed using the front-side MIG / MAG welding wire. The method includes the following steps: S1. Beveling the edges of the plates to be welded, using a single-sided beveling structure, with the beveling angle controlled between 10° and 90°; at the same time, adjusting the butt joint gap of the plates to be welded, controlling the gap to be 0.5 to 2 mm, and the blunt edge size to be controlled between 0.2 and 3 mm. S2. Set up the welding equipment: Fix the TIG welding gun on the back of the plate, and align the TIG electrode with the center of the back of the plate butt groove; fix the single-wire or double-wire MIG / MAG welding gun on the front of the plate, and align the MIG / MAG electrode with the center of the front of the plate butt groove, ensuring that the axes of the front MIG / MAG electrode and the back TIG electrode are in the same vertical plane and directly facing the plate butt groove. S3. An indirect arc welding mode is adopted, which only supplies power to the front MIG / MAG electrode and the back TIG electrode, and the base material is not connected to the power. S4. Turn on the power supply to simultaneously ignite the TIG arc on the back and the MIG / MAG arc on the front, so that a stable indirect arc is formed between the front MIG / MAG electrode and the back TIG electrode, and the arc energy is concentrated between the two electrodes. S5. The heat generated by the indirect arc melts the MIG / MAG welding material on the front side. Under the action of arc force and gravity, the molten droplets transfer to the back side of the plate through the gap between the plates. The heat generated by the TIG arc on the back side works together with the heat generated by the TIG arc on the back side to form a uniform root pass weld at the plate joint. The TIG arc on the back side plays a role in assisting melting and controlling the back side forming, ensuring a smooth surface of the back side weld. S6. During the root pass welding process, control the welding speed to 5~20cm / min, adjust the indirect arc current to 80~250A and the voltage to 18~32V according to the plate thickness, and maintain a continuous supply of shielding gas. The shielding gas should be argon or a mixture of argon and carbon dioxide, and the flow rate should be controlled at 15~30L / min.

[0008] Key parameter limitations: (1) Butt gap: 0.5~2mm. Unlike traditional double-sided arc welding, there must be a specific width of gap between the plates of indirect arc welding, otherwise the arc cannot penetrate the plate. If the gap is too small, the droplet transfer will be poor and a continuous weld will not be formed. If the gap is too large, the droplet will be lost, the back side forming will be difficult to control, and the risk of welding deformation will increase. (2) Bevel angle: The bevel angle is controlled between 10° and 90°. If the angle is too small, it will be difficult to fill the welding material and easy to produce incomplete penetration defects; if the angle is too large, it will increase the amount of welding material, increase the welding cost, and increase the heat input, which is not conducive to controlling the deformation of the plate. (3) Blunt edge size: 0.2~3mm. If the blunt edge is too small, it will easily lead to burn-through. If it is too large, it will affect the weld penetration depth and lead to incomplete penetration. We must take into account both welding quality and forming stability.

[0009] Compared with the prior art, the present invention has the following significant advantages: (1) Controllable heat input and small plate deformation: The present invention adopts an indirect arc welding mode, where the arc burns only between the front MIG / MAG electrode and the back TIG electrode, and the base material is not connected to the power supply, thus avoiding direct impact of the arc on the base material, greatly reducing the welding heat input, effectively reducing the welding deformation of the plate, and improving the dimensional accuracy and mechanical properties of the welded joint. (2) Achieve single-sided welding and double-sided forming without secondary grinding: The back side is formed by TIG arc-assisted control. Taking advantage of the concentrated heat and regular forming of TIG arc, the surface of the back weld is smooth and uniform, eliminating the need for subsequent secondary grinding, reducing the number of processes, lowering production costs, and improving production efficiency. (3) High welding efficiency and suitable for mass production: The front side is filled and covered by single-wire or double-wire MIG / MAG arc. Compared with traditional TIG welding or single-wire MIG welding, the deposition efficiency is greatly improved. In particular, the double-wire MIG / MAG mode can further shorten the welding time and meet the needs of industrial mass production. (4) Stable welding quality and wide applicability: By precisely controlling the bevel angle, butt gap, blunt edge size and welding parameters, the weld formation is ensured to be good and free from defects such as incomplete penetration, porosity and cracks. It is applicable to the welding of various materials such as carbon steel, stainless steel and aluminum alloy, and has a wide range of applications. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the welding process of the present invention; Figure 2 This is the cross-section of the welded joint of the present invention; In the diagram: 1. TIG welding torch; 2. MIG / MAG welding torch; 3. Base material; 4. Weld seam; 5. Welding machine. Detailed Implementation

[0012] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0013] Example 1: Indirect arc welding of stainless steel sheet with single-wire MIG + TIG back side.

[0014] like Figure 1 As shown, a double-sided indirect arc welding method includes the following steps: S1. Welding preparation; The plates to be welded are 304 stainless steel plates, 2mm thick, and the two plates are butt-welded. Welding preparation includes: removing oil and oxide scale from the plate surface, machining a single-sided bevel with a bevel angle of 20°, a butt joint gap of 0.5mm, and a blunt edge of 1mm. S2. Fix the TIG welding gun 1 to the back of the plate and align the electrode with the center of the back of the bevel. Fix the single-wire or double-wire MIG / MAG welding gun 2 to the front of the plate and align the electrode with the center of the front of the bevel, ensuring that the axes of the two electrodes are in the same vertical plane and directly facing the bevel. S3: Only the front MIG / MAG electrode and the back TIG electrode are powered; the base material 3 is not connected to power. S4. Start the power supply of welding machine 5, and ignite the TIG arc on the back and the MIG / MAG arc on the front at the same time, so that a stable indirect arc is formed between the two electrodes. S5. The heat generated by the indirect arc melts the front MIG / MAG welding material. Under the action of arc force and gravity, the molten droplets transition to the back of the plate through the gap between the plates. The heat generated by the back TIG arc works together with the heat generated by the back TIG arc to form a uniform root pass weld at the plate joint. The back TIG arc plays a role in assisting melting and controlling the back form, ensuring a smooth back weld surface.

[0015] Welding parameters include: indirect arc current 120A, voltage 25V, welding speed 20cm / min, shielding gas is pure argon with a flow rate of 20L / min, MIG welding material for the front side is ER308L, and wire feed speed is 3m / min.

[0016] The welding results are as follows: the deformation of the plate is ≤0.5mm, the surface of the back weld is smooth, without burrs or dents, the front cover weld is well formed and without defects, no secondary grinding is required, and the tensile strength of the welded joint reaches more than 380MPa, which meets the stainless steel welding standard.

[0017] Example 2: Double-wire MAG + TIG double-sided indirect arc welding of carbon steel plates.

[0018] S1. Welding preparation; The plates to be welded are Q235 carbon steel plates, 6mm thick, and the two plates are butt-welded. The welding preparation includes: removing rust and oil from the plate surface, machining a single-sided bevel with a bevel angle of 30°, a butt gap of 1mm, and a blunt edge of 2mm; S2. Fix the TIG welding gun 1 to the back of the plate and align the electrode with the center of the back of the bevel. Fix the single-wire or double-wire MIG / MAG welding gun 2 to the front of the plate and align the electrode with the center of the front of the bevel, ensuring that the axes of the two electrodes are in the same vertical plane and directly facing the bevel. S3: Only the front MIG / MAG electrode and the back TIG electrode are powered; the base material 3 is not connected to power. S4. Start the power supply of welding machine 5, and ignite the TIG arc on the back and the MIG / MAG arc on the front at the same time, so that a stable indirect arc is formed between the two electrodes. S5. The heat generated by the indirect arc melts the front MIG / MAG welding material. Under the action of arc force and gravity, the molten droplets transition to the back of the plate through the gap between the plates. The heat generated by the back TIG arc works together with the heat generated by the back TIG arc to form a uniform root pass weld at the plate joint. The back TIG arc plays a role in assisting melting and controlling the back form, ensuring a smooth back weld surface.

[0019] The welding parameters for the root pass welding include: indirect arc current 200A, voltage 30V, welding speed 15cm / min, shielding gas is argon + carbon dioxide mixture (volume ratio 8:2) with a flow rate of 25L / min, the MAG welding material for the front pass is H08Mn2SiA, and the wire feed speed is 7m / min.

[0020] The welding result is as follows: the cross-section of the joint after welding is as shown. Figure 2 As shown. The deformation of the plate is ≤0.8mm, the weld on the back is smooth, the weld on the front cover is full, and there are no defects such as incomplete penetration or porosity. No secondary grinding is required. The welding efficiency is more than 60% higher than that of single-wire welding, and the mechanical properties of the welded joint meet the requirements for carbon steel welding.

[0021] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-sided indirect arc welding method, characterized in that, TIG (Tungsten Inert Gas) electrodes are positioned on the back of the substrate, while MIG / MAG (Metal Inert Gas) electrodes (single-wire or dual-wire) are positioned on the front of the substrate; including: S1. Process a single-sided bevel on the edge of the plate to be welded; S2. Fix the TIG welding gun to the back of the plate and align the electrode with the center of the back of the bevel. Fix the single-wire or double-wire MIG / MAG welding gun to the front of the plate and align the electrode with the center of the front of the bevel, ensuring that the axes of the two electrodes are in the same vertical plane and directly facing the bevel. S3: Only the front MIG / MAG electrode and the back TIG electrode are powered; the base material is not connected to power. S4. Turn on the power supply to simultaneously ignite the TIG arc on the back and the MIG / MAG arc on the front, so that a stable indirect arc is formed between the two electrodes. S5. While completing the root pass welding through the indirect arc, the fill pass welding is completed through the front MIG / MAG welding wire, and the forming is controlled by the back TIG arc.

2. The double-sided indirect arc welding method according to claim 1, characterized in that, Adjust the gap between the plates to 0.5~2mm.

3. The double-sided indirect arc welding method according to claim 1, characterized in that, The bevel angle is 10°~90°.

4. The double-sided indirect arc welding method according to claim 3, characterized in that, Adjust the blunt edge size to 0.2~3mm.

5. The double-sided indirect arc welding method according to claim 1, characterized in that, During the root pass welding, control the welding speed to 5~20cm / min, the indirect arc current to 80~250A, the voltage to 18~32V, and continuously supply the shielding gas, which is argon or a mixture of argon and carbon dioxide, with a flow rate of 15~30L / min.

6. The double-sided indirect arc welding method according to claim 5, characterized in that, When the protective gas is a mixture of argon and carbon dioxide, the mixing ratio is adjusted according to the material of the welding plate.

7. The double-sided indirect arc welding method according to claim 1, characterized in that, The method is applicable to welding plates made of carbon steel, stainless steel, and aluminum alloy.

8. The double-sided indirect arc welding method according to claim 1, characterized in that, Before welding, it is also necessary to remove impurities from the surface of the plate to be welded.

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