An asymmetric ring electrode cap and its matching welding device

Abstract

The application discloses an asymmetric ring electrode cap, discards the traditional two-side uniform spherical electrode design, and adopts an asymmetric ring electrode structure, specifically, the welding end face diameter of a thin plate side electrode cap is 6-14 mm, the curvature radius is 40-100 mm, three rings are arranged, the inner ring is provided with a conical pit, and the middle ring is in the shape of an isosceles trapezoid; the welding end face diameter of a thick plate side electrode cap is not less than that of the thin plate side and not more than 14 mm, the curvature radius is not less than that of the thin plate side and not more than 100 mm, three rings are also arranged, the inner ring is provided with a conical pit, and the middle ring is in the shape of an equilateral triangle. The ring structure parameters of the two electrode caps are accurately designed to adapt to the welding requirements of plates with different thicknesses, and the welding quality and efficiency are improved. The application is particularly suitable for resistance spot welding of materials such as aluminum workpieces with large thickness ratios.

Description

Technical Field

[0001] The present invention relates to the field of resistance spot welding, and in particular to an asymmetric ring electrode cap and a matching welding device thereof, which can effectively control the deviation of the resistance spot welding nugget of an aluminum workpiece. Background Art

[0002] Resistance spot welding, a complex process involving multiple variables, plays a crucial role in the automotive manufacturing industry, particularly in the field of steel joining. However, with the increasing global emphasis on energy conservation and emission reduction, coupled with the booming new energy vehicle industry, lightweighting vehicles has become a key approach to alleviating energy shortages and environmental pollution. The use of aluminum alloys is one effective way to reduce vehicle weight. Among the many aluminum alloy joining technologies, resistance spot welding, due to its unique advantages such as high efficiency, low cost, high flexibility, and no weight increase, has become the preferred method for achieving large-scale mass production of aluminum alloy components.

[0003] However, the types and thicknesses of aluminum alloy sheets used in different parts of a vehicle often vary significantly. In some cases, even large thickness ratios (such as 3:1 to 4:1) are required. Resistance spot welding under these high thickness ratios presents a significant challenge: the nugget is often excessively concentrated on the thicker side, while the thinner side barely forms a nugget. This directly reduces the strength of the weld joint, posing a potential threat to the overall safety of the vehicle.

[0004] Patent CN109014535A discloses a method for spot welding aluminum plates of unequal thickness. By varying the curvature of the electrode cap end face, the effective contact area between the electrode cap and the plate is altered, thereby varying the current density and penetration depth. This effectively balances the heat distribution in the plates of unequal thickness, thereby alleviating the problem of nugget shift. However, a significant side effect is that the higher current density accelerates pitting corrosion of the electrode, requiring frequent electrode grinding and thus affecting the overall efficiency of resistance spot welding.

[0005] Patent CN111014923A discloses a device and method for resistance spot welding of plates of unequal thickness. This method uses a small-section annular electrode on the thin plate side and adds ceramic material inside the electrode ring, while using a circular-section copper electrode on the thick plate side. During welding, because the welding end surface of the small-section annular electrode is much smaller than that of the circular-section copper electrode, the current density on the thin plate side is much greater than that on the thick plate side, increasing heat dissipation on the thin plate side. The addition of ceramic material can also reduce heat loss on the thin plate, thereby causing the resistance spot welding nugget to shift toward the thin plate side. Although this method also improves nugget shift by increasing the current density on the thin plate side, it also faces the problem of premature pitting of the electrode, which has a potential impact on welding efficiency. Summary of the Invention

[0006] The purpose of the present application is to provide an asymmetric ring electrode cap and its matching welding device, which can effectively weld aluminum alloy pieces with different thicknesses, make the nugget deviate to the thin plate side, increase the penetration of the thin plate side, and make the nugget meet the requirements of the aluminum alloy resistance spot welding standard.

[0007] The technical solution of the present application is as follows:

[0008] An asymmetric ring electrode cap, characterized in that it is composed of a thin plate side electrode cap (11) and a thick plate side electrode cap (12) used in matching,

[0009] The thin plate side electrode cap comprises an electrode cap body, a thin plate side surface (3), and a thin plate welding end surface (4), the diameter of the thin plate welding end surface (4) is d2, and the curvature radius is R1, wherein 6mm≤d2≤14mm and 40mm≤R1≤100mm;

[0010] The thick plate side electrode cap comprises an electrode cap body, a thick plate side surface (8), and a thick plate welding end surface (5), the diameter of the thick plate welding end surface (5) is d3, and the curvature radius is R2, wherein d2≤d3≤14mm and R1≤R2≤100mm;

[0011] The thin plate welding end surface (4) is a welding end surface corresponding to the thin plate side, and the thick plate welding end surface (5) is a welding end surface corresponding to the thick plate side;

[0012] The thin plate welding end surface (4) has three rings, wherein the inner ring has a structure in the form of a conical pit in the middle, the depth of the conical pit is h1, the diameter is d6, the diameter to the inner ring is d7, and 0.05mm≤h1≤1mm, 0.05mm≤d6≤d7≤14mm are satisfied; the height of the middle ring is h3, the ring width is d4, the ring spacing is d5, the cross-sectional dimensions of each ring are equal, the cross-sectional shape is isosceles trapezoidal, the oblique side is 45°, and 0.05mm≤h3≤1mm, 0.05mm≤d4≤d5≤1mm are satisfied;

[0013] The thick plate welding end surface (5) has three rings, wherein the inner ring has a structure in the form of a conical pit in the middle, the depth of the conical pit is h2, the diameter is d10, the diameter to the inner ring is d11, and 0.05mm≤h2≤1mm, 0.05mm≤d10≤d11≤14mm are satisfied; the height of the middle ring is h4, the ring width is d8, the ring spacing is d9, the cross-sectional dimensions of each ring are equal, the cross-sectional shape is equilateral triangle, and 0.05mm≤h4≤1mm, 0.05mm≤d8≤d9≤1mm are satisfied.

[0014] Further, the diameter of the thin plate welding end surface (4) is d2, the diameter of the thick plate welding end surface (5) is d3, and 6mm≤d2≤d3≤14mm are satisfied.

[0015] Further, the thin plate welding end face (4) has a radius of curvature R1, and the thick plate welding end face (5) has a radius of curvature R2, and 40mm≤R1≤R2≤100mm.

[0016] In another aspect, the present application also provides a welding device for welding thin plate aluminum workpieces (15) and thick plate aluminum workpieces (14) using the above-mentioned asymmetric ring electrode cap, characterized in that it comprises:

[0017] a first welding gun arm (9) and a second welding gun arm (10);

[0018] a thin plate side electrode cap (11) mounted on the first welding gun arm (9);

[0019] a thick plate side electrode cap (12) mounted on the second welding gun arm (10);

[0020] wherein the thin plate aluminum workpieces (15) are deformed aluminum alloys with a thickness of 0.5-2.5mm, and the thick plate aluminum workpieces (14) are composed of cast aluminum or deformed aluminum alloys with a thickness of 2.5-6mm.

[0021] During welding, the welding gun arms are operated to make the thin plate side electrode cap (11) and the thick plate side electrode cap (12) tightly adhere to the thin plate aluminum workpieces (15) and the thick plate aluminum workpieces (14), and apply pressure clamping, so that the two aluminum workpiece adhesion parts are melted to form a nugget (16).

[0022] The present application also provides a resistance spot welding method, which comprises:

[0023] (a) providing a pair of the above-mentioned electrode caps, with the electrode cap of the welding end face 4 placed on the thin plate side and the electrode cap of the welding end face 5 placed on the thick plate side.

[0024] (b) pre-pressing stage: placing the electrode caps on the two sides of the stacked aluminum workpieces with different thicknesses, without constraining the positive and negative electrodes, performing pre-pressing, the positive electrode approaching the aluminum alloy plate until the welding end face tightly adheres to the plate, applying a pressure of 2500-6000N, and the pre-pressing duration being 200-2000ms;

[0025] (c) current welding stage: passing a welding current, the effective value of the welding current being 15-60kA, and the current welding time being 80-200ms.

[0026] (d) cooling stage: after the welding current is stopped, the electrode caps remain pressed on the two sides of the plate for 30-400ms, and the melted metal solidifies to form a welding spot.

[0027] The mechanism of the present invention is as follows: Taking the welding of two aluminum alloy workpieces of unequal thickness as an example, for symmetrical electrodes without the aforementioned special design, during welding, due to the thinner thickness of the thin plate, the electrode dissipates heat better at the thin plate than at the thick plate. Furthermore, the bulk resistance of the thick plate is much greater than that of the thin plate. Therefore, the thin plate generates resistive heat due to the contact resistance between the two plates, while the thick plate generates resistive heat due to both bulk resistance and contact resistance. Overall, the thick plate generates much more heat than the thin plate, while dissipating much less heat than the thin plate. This results in uneven heat distribution between the thin and thick plates, causing the weld nugget to shift toward the thick plate after welding. However, when the specially designed electrode cap is used during welding, the asymmetric ring design on both sides means that the area of ​​the thin plate that initially contacts the electrode is smaller than that of the thick plate. This increases heat generation on the thin plate during welding, maintaining a higher temperature and causing the weld nugget to shift toward that side. This controls the weld nugget's shift toward the thin plate, increasing the depth of penetration on the thin plate.

[0028] Technical effect: Since the contact area between the contact surface 4 and the thin plate 6 is smaller than the contact area between the contact surface 5 and the thick plate 7 during welding, the heat generation at the thin plate can be increased, thereby extending the weld nugget to a certain depth at the thin plate, so that the weld nugget depth at the thin plate meets the resistance spot welding standard.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) The present invention utilizes a pair of asymmetric ring electrode caps to weld thin and thick aluminum workpieces, respectively. This design allows the electrode caps to better adapt to aluminum workpieces of varying thicknesses, ensuring stability and reliability during welding.

[0031] 2) The difference in shape and size between the thin plate welding end face and the thick plate welding end face helps to control the offset of the molten core during the welding process, which can optimize the performance of the weld joint, improve the welding quality and reduce welding defects.

[0032] 3) By providing ring structures of different shapes and sizes, as well as features such as conical pits on the welding end face of the electrode cap, welding current and heat can be transferred more effectively, thereby improving welding efficiency and quality. At the same time, it helps to reduce defects such as spatter and cracks during the welding process.

[0033] 4) A device for welding aluminum workpieces using asymmetric ring electrode caps. The first and second welding gun arms are equipped with asymmetric electrode caps for thin and thick plates, respectively, enabling stable welding of aluminum workpieces of varying thicknesses. The device also features standard electrode caps, allowing for flexible switching between them as needed, enhancing its flexibility and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other alternative implementation methods can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 An embodiment using an asymmetric ring electrode cap is shown.

[0036] Figure 2 express Figure 1 One embodiment of a partial elevation view cross section.

[0037] Figure 3 express Figure 1 Outline dimensions of middle contact surface 4 and contact surface 5

[0038] Figure 4 A partial side view showing an aluminum alloy workpiece during resistance spot welding.

[0039] Figure 5 A schematic diagram illustrating actual current output during a resistance spot welding process according to one embodiment.

[0040] Figure 6 Represents the cross-sectional view of the weld nugget with a plate thickness ratio of 1:2.5 for a symmetrical spherical ring electrode.

[0041] Figure 7 Represents the cross-sectional view of the weld nugget with a plate thickness ratio of 1:3 for a symmetrical spherical ring electrode.

[0042] Figure 8 A cross-sectional diagram of the weld nugget with a plate thickness ratio of 1:2.5 for the new asymmetric spherical ring electrode.

[0043] Figure 9 A cross-sectional diagram of the weld nugget with a plate thickness ratio of 1:2.5 for the new asymmetric spherical ring electrode.

[0044] Figure 10 A cross-sectional diagram of the weld nugget with a plate thickness ratio of 1:2.5 for the new asymmetric spherical ring electrode.

[0045] Figure 11 A cross-sectional view of the weld nugget with a plate thickness ratio of 1:3 for the new asymmetric spherical ring electrode.

[0046] In the accompanying drawings, the following are marked:

[0047] 1-Electrode cap cylinder

[0048] 2-Cooling water return tank

[0049] 3-Side of thin plate electrode cap

[0050] 4-Welding end face of thin plate

[0051] 5-Welding end face of thick plate side

[0052] 6-Thin sheet aluminum workpiece

[0053] 7-Thick plate aluminum workpiece

[0054] 8-Thick plate side electrode cap side

[0055] 9, 10- welding gun arm

[0056] 11-Thin plate side electrode cap

[0057] 12-Thick Plate Side Electrode Cap

[0058] 13-Ordinary electrode cap

[0059] 14-Welding thick aluminum workpieces

[0060] 15-Welding thin aluminum workpieces

[0061] 16-Welding nugget DETAILED DESCRIPTION

[0062] The present invention will be further described below with reference to the examples and accompanying drawings. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. In addition, the accompanying drawings are schematic diagrams, and therefore the devices and apparatuses of the present invention are not limited by the dimensions or proportions of the schematic diagrams.

[0063] Example 1: Asymmetric Ring Electrode Cap

[0064] This embodiment provides a pair of asymmetric ring electrode caps, which are particularly suitable for resistance spot welding of aluminum workpieces with large thickness ratios. Figure 1 As shown, it includes an electrode cap designed for the thin plate side and an electrode cap designed for the thick plate side. The thin plate side electrode cap is composed of a thin plate electrode cap body, a thin plate side surface 3 and a thin plate welding end face 4, wherein the diameter of the thin plate welding end face 4 is d2 and the radius of curvature is R1. Correspondingly, the thick plate side electrode cap includes a thick plate electrode cap body, a thick plate side surface 8 and a thick plate welding end face 5, wherein the diameter of the thick plate welding end face 5 is d3 and the radius of curvature is R2. The thin plate welding electrode cap end face 4 corresponds to the thin plate 6 side welding end face, and the thick plate welding electrode end face 5 corresponds to the thick plate 7 side welding end face. The thin plate side welding end face 4 and the thick plate side welding end face 5 are different in shape and size to accommodate aluminum workpieces of different thicknesses and to achieve offset control of the weld core, as shown in FIG. Figure 3As shown, the diameter of the thin plate welding end face 4 is d2, and the diameter of the thick plate welding end face 5 is d3, and they satisfy 6mm≤d2≤d3≤14mm. The curved radius of the thin plate welding end face 4 is R1, and the curved radius of the thick plate welding end face 5 is R2, and they satisfy 40mm≤R1≤R2≤100mm.

[0065] The thin plate welding end face 4 and the thick plate welding end face 5 are different in shape and size to accommodate aluminum workpieces of different thicknesses and to achieve offset control of the weld nugget. Three rings are machined on both welding end faces, with a conical pit in the middle of the inner ring. For the thin plate welding end face 4, the depth of the conical pit is h1, the diameter is d6, and the diameter to the inner ring is d7, and it satisfies 0.05mm≤h1≤1mm, 0.05mm≤d6≤d7≤14mm. The height of the ring in the thin plate welding end face 4 is h3, the ring width is d4, and the ring spacing is d5. The cross-sectional dimensions of each ring are equal, the cross-sectional shape is an isosceles trapezoid, the hypotenuse is 45°, and it satisfies 0.05mm≤h3≤1mm, 0.05mm≤d4≤d5≤1mm. For the thick plate weld end face 5, the conical pit has a depth of h2, a diameter of d10, and a diameter to the inner ring of d11, satisfying the following conditions: 0.05mm≤h2≤1mm, 0.05mm≤d10≤d11≤14mm. The ring height in the thick plate weld end face 5 is h4, the ring width is d8, and the ring spacing is d9. The cross-sectional dimensions of each ring are equal, forming an equilateral triangle, and satisfying the following conditions: 0.05mm≤h4≤1mm, 0.05mm≤d8≤d9≤1mm.

[0066] In a preferred embodiment, the diameter d2 of the thin plate side welding end surface is 8-12 mm, the diameter d3 of the thick plate side welding end surface is 8-12 mm, the curvature radius of the thin plate side welding end surface is 40 mm, and the curvature radius of the thick plate side welding end surface is 50 mm.

[0067] Example 2: Welding device and welding process

[0068] like Figure 4 As shown in Figure 2b, this embodiment also provides an apparatus and welding process for welding aluminum workpieces using an asymmetric ring electrode cap. The apparatus includes a first welding gun arm 9, a second welding gun arm 10, a thin plate electrode cap 11, a thick plate electrode cap 12, and a standard electrode cap 13 (spare). The welded objects include a thick plate aluminum workpiece 14 and a thin plate aluminum workpiece 15. The thin plate aluminum workpiece 15 is made of a deformed aluminum alloy with a thickness of 0.5-2.5 mm, while the thick plate aluminum workpiece 14 is made of cast aluminum or a deformed aluminum alloy with a thickness of 2.5-6 mm.

[0069] The welding process is as follows:

[0070] ① Before welding, the electrode cap does not touch the aluminum workpiece;

[0071] ② During welding, operate the welding gun arm so that the two electrodes are closely attached to the thin plate aluminum workpiece 14 and the thick plate aluminum workpiece 15, and apply pressure to clamp them so that the attached parts of the two aluminum workpieces melt to form a molten core 16.

[0072] ③ Welding parameters can be adjusted according to actual conditions, including the pre-pressing stage (duration 200-2000ms), the power-on welding stage (welding current effective value 15-60kA, power-on time 80-200ms) and the cooling stage (duration 30-400ms).

[0073] Example 3

[0074] like Figure 6 Shown is the use of common symmetrical electrodes and the Figure 4 The welding device in a Figure 5 Cross-sectional morphology of the weld nugget after resistance spot welding of 0.95 mm thick 5754 wrought aluminum alloy and 4.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, there is almost no weld nugget on the thinner side.

[0075] like Figure 7 Shown is the use of common symmetrical electrodes and the Figure 4 The welding device in a Figure 5 Cross-sectional morphology of the weld nugget after resistance spot welding of 0.95 mm thick 5754 wrought aluminum alloy and 4.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, there is almost no weld nugget on the thinner side.

[0076] Example 4

[0077] like Figure 8 The figure shows a symmetrical ring electrode cap with both upper and lower welding end faces being welding end faces 5 and using Figure 4 The welding device in b and Figure 5 Cross-sectional morphology of the weld nugget after resistance spot welding of 2.0 mm thick 5754 wrought aluminum alloy and 5.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, there is almost no weld nugget on the thinner side.

[0078] like Figure 9 The figure shows a symmetrical ring electrode cap with both upper and lower welding end faces being welding end faces 5 and using Figure 4 The welding device in b and Figure 5 Cross-sectional morphology of the weld nugget after resistance spot welding of a 2.0 mm thick 5754 wrought aluminum alloy and a 6.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, there is almost no weld nugget on the thinner side.

[0079] Example 5

[0080] like Figure 10 The figure shows an asymmetric ring electrode cap with the thin plate side welding end face as welding end face 4 and the thick plate side welding end face as welding end face 5. Figure 4 The welding device in b and Figure 5 The cross-sectional morphology of the weld nugget after resistance spot welding of a 2.0 mm thick 5754 wrought aluminum alloy and a 5.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, a larger amount of weld nugget melted toward the thinner sheet.

[0081] like Figure 11 The figure shows an asymmetric ring electrode cap with the thin plate side welding end face as welding end face 4 and the thick plate side welding end face as welding end face 5. Figure 4 The welding device in b and Figure 5 Cross-sectional morphology of the weld nugget after resistance spot welding of a 2.0 mm thick 5754 wrought aluminum alloy and a 6.0 mm thick AlSi10MnMg cast aluminum alloy using the welding parameters shown. As can be seen, a larger amount of weld nugget melts toward the thinner sheet.

[0082] The present invention also provides a resistance spot welding method, comprising the following steps:

[0083] (a) providing a pair of the above-mentioned asymmetric ring electrode caps placed on both sides of the thin plate and the thick plate, with the two welding end faces having different curvatures and the specially designed ring electrode caps;

[0084] (b) Pre-pressing stage: The electrode caps are placed on both sides of two stacked aluminum workpieces of unequal thickness. The positive and negative electrodes are not constrained. Pre-pressing is performed, with the positive electrode moving closer to the aluminum alloy sheet until the weld end face is tightly fitted to the sheet. A pressure of 2500-6000 N is applied, and the pre-pressing duration is 200-2000 ms.

[0085] (c) Power-on welding stage: a welding current is applied, the effective value of the welding current is 15-60 kA, and the power-on time is 80-200 ms.

[0086] (d) Cooling stage: After the welding current stops, the electrode caps remain pressed against both sides of the plate for 30-400ms, and the molten metal solidifies to form a weld.

[0087] The asymmetric ring electrode cap and its welding device and method provided in the embodiment of the present invention abandon the traditional design of uniform spherical electrodes on both sides and instead adopt an asymmetric ring electrode structure, which realizes effective offset control of the molten core during the resistance spot welding process of aluminum workpieces, significantly improving the welding quality and efficiency.

[0088] Although embodiments of the present invention have been shown and described above, these embodiments are illustrative and should not be construed as limiting the present invention. Within the scope of the claims, adjustments to various embodiments, provided they do not conflict, fall within the scope of the present invention. Within the scope of the present invention, the above-described technical features of the present invention and those described in detail below (e.g., in the Examples) may be combined to form new or preferred technical solutions. Due to space limitations, these are not detailed here.

Claims

1. An asymmetric ring electrode cap, characterized in that: It is composed of a thin plate side electrode cap (11) and a thick plate side electrode cap (12) used in conjunction with each other. The thin plate side electrode cap comprises an electrode cap body, a thin plate side surface (3) and a thin plate welding end surface (4), wherein the diameter of the thin plate welding end surface (4) is d2 and the curvature radius is R1, wherein 6mm≤d2≤14mm, 40mm≤R1≤100mm; The thick plate side electrode cap comprises an electrode cap body, a thick plate side surface (8) and a thick plate welding end surface (5), wherein the diameter of the thick plate welding end surface (5) is d3 and the curvature radius is R2, wherein d2≤d3≤14mm, R1≤R2≤100mm; Wherein, the thin plate welding end face (4) is the welding end face corresponding to the thin plate side, and the thick plate welding end face (5) is the welding end face corresponding to the thick plate side; The thin plate welding end face (4) has three rings, wherein the inner ring has a structure in the shape of a conical pit in the middle, the depth of the conical pit is h1, the diameter is d6, the diameter to the inner ring is d7, and the conditions are 0.05mm≤h1≤1mm, 0.05mm≤d6≤d7≤14mm; the height of the middle ring is h3, the ring width is d4, the ring spacing is d5, the cross-sectional dimensions of each ring are equal, the cross-sectional shape is an isosceles trapezoid, the hypotenuse is 45 degrees, and the conditions are 0.05mm≤h3≤1mm, 0.05mm≤d4≤d5≤1mm; The thick plate welding end face (5) has three rings, wherein the middle of the inner ring has a structure in the shape of a conical pit, the depth of the conical pit is h2, the diameter is d10, the diameter to the inner ring is d11, and it satisfies 0.05mm≤h2≤1mm, 0.05mm≤d10≤d11≤14mm; the height of the middle ring is h4, the ring width is d8, the ring spacing is d9, the cross-sectional dimensions of each ring are equal, the cross-sectional shape is an equilateral triangle, and 0.05mm≤h4≤1mm, 0.05mm≤d8≤d9≤1mm.

2. The asymmetric ring electrode cap according to claim 1, characterized in that: The diameter of the thin plate welding end surface (4) is d2, the diameter of the thick plate welding end surface (5) is d3, and 6mm≤d2≤d3≤14mm.

3. The asymmetric ring electrode cap according to claim 1, characterized in that: The curved surface radius of the thin plate welding end surface (4) is R1, the curved surface radius of the thick plate welding end surface (5) is R2, and 40mm≤R1≤R2≤100mm.

4. A welding device for welding aluminum workpieces using an asymmetric ring electrode cap according to any one of claims 1 to 3, used for welding thin aluminum workpieces (15) and thick aluminum workpieces (14), characterized in that: include: A first welding gun arm (9) and a second welding gun arm (10); a thin plate side electrode cap (11) mounted on the first welding gun arm (9); A thick plate side electrode cap (12) mounted on the second welding gun arm (10); The thin-plate aluminum workpiece (15) is made of deformed aluminum alloy and has a thickness of 0.5-2.5 mm; the thick-plate aluminum workpiece (14) is made of cast aluminum or deformed aluminum alloy and has a thickness of 2.5-6 mm.

5. The welding device according to claim 4, characterized in that During welding, the welding gun arm is operated to make the thin plate side electrode cap (11) and the thick plate side electrode cap (12) closely fit the thin plate aluminum workpiece (15) and the thick plate aluminum workpiece (14), and pressure is applied to clamp them so that the fitting parts of the two aluminum workpieces are melted to form a molten core (16).

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