Aluminum alloy small-gap duct welding method

Abstract

The invention provides an aluminum alloy small-gap duct welding method. The aluminum alloy small-gap duct welding method comprises the steps that S1, a stainless steel wire brush is adopted for removing oxidation films on the to-be-welded faces of a duct and a plate; s2, a first hole channel is assembled in the plate in a spot welding mode through argon arc welding; s3, preheating the surface to be welded; s4, the whole circle of the first hole channel is welded through a common welding gun; s5, a second hole channel is assembled in the plate in a spot welding mode through argon arc welding; s6, the surface to be welded is preheated; s7, a lengthened elbow welding gun is adopted for welding the whole circle of the second hole channel; and S8, the staggered hole channel welding sequence is adopted, the steps S5-S7 are repeated, and welding of all hole channels is completed. The mode that the circular step is reserved on the plate is adopted, the situation that heat is rapidly dissipated to large-thickness base metal in the welding process is relieved, the current needed by welding is reduced, and then welding deformation is reduced. A single-pass welding forming process is adopted, welding deformation is reduced, and welding efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of welding methods, and more specifically, to a welding method for small-gap channels in aluminum alloys. Background Technology

[0002] Argon arc welding (argon arc welding) is a widely used welding method characterized by stable welding process and minimal welding deformation, making it suitable for welding materials such as stainless steel and aluminum alloys. The aluminum alloys described in this application (such as 5052 and 6061) are commonly used in the manufacture of products such as aircraft, automobiles, and nuclear power plants.

[0003] The heavy water tank of an isotope reactor in nuclear power plants has a complex structure with numerous welds. Its densely packed channels and the upper and lower plates of the heavy water tank require argon arc welding. These channels are often slender straight pipes welded onto thick plates. The welds on the pipes are fillet welds, and liquid penetration testing is required after welding. The weld quality requirements are high.

[0004] Because aluminum alloys have high thermal conductivity and rapid heat dissipation, high currents are required for welding thick plates, which causes significant damage to the welding torch and tungsten electrode, necessitating frequent replacements and making it difficult to guarantee weld quality. The channels in heavy water tanks are long and densely distributed with small gaps, typically 20-40mm. Traditional argon arc welding offers poor weldability and fails to meet the requirements for channel welding. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for welding small-gap channels in aluminum alloys.

[0006] A method for welding small-gap channels in aluminum alloys according to the present invention includes the following steps:

[0007] Step S1: Use a stainless steel wire brush to remove the oxide film from the holes and the plate to be welded, and wipe the surface to be welded with acetone to clean it.

[0008] Step S2: The first hole is assembled by spot welding on the plate using argon arc welding;

[0009] Step S3: Preheat the surface to be welded using an oxyacetylene flame;

[0010] Step S4: Use a conventional welding torch and argon arc welding machine to weld the entire circle of the first channel;

[0011] Step S5: Use argon arc welding to spot weld the second channel onto the plate.

[0012] Step S6: Preheat the surface to be welded using an oxyacetylene flame;

[0013] Step S7: Use an extended elbow welding gun and an argon arc welding machine to weld the second duct around its entire circumference.

[0014] Step S8: Select the welding sequence of the channels using the staggered welding method and weld them. Repeat steps S5-S7 to complete the welding of all channels.

[0015] Preferably, in step S1, welding should be performed within 4 hours after removing the oxide film from the surface to be welded.

[0016] Preferably, in step S1, the plate has a step pre-reserved for fusion with the channel.

[0017] Preferably, the step is configured as an annular shape, and the inner diameter of the step is adapted to the outer diameter of the channel.

[0018] Preferably, in steps S2 and S5, the duct to be welded is fixed by uniform double-sided spot welding using argon arc welding.

[0019] Preferably, in steps S3 and S6, the preheating temperature is 100-150°C.

[0020] Preferably, in step S4, the ordinary welding torch of the ordinary welding torch argon arc welding machine includes: a first hand-held section, a first flow guide nozzle, and a first tungsten rod;

[0021] One end of the first hand-held segment is fitted with a first tungsten rod via a first guide nozzle.

[0022] Preferably, in step S7, the extended elbow welding torch of the extended elbow welding torch argon arc welding machine includes: a second hand-held section, a second guide nozzle, a second tungsten rod, an extended tube, and a bend.

[0023] One end of the second hand-held section is connected to an extension tube, the extension tube is connected to a bend tube, and one end of the bend tube is fitted with a second tungsten rod through a second guide nozzle.

[0024] Preferably, the first tungsten rod and the second tungsten rod are made of lanthanum tungsten or zirconium tungsten.

[0025] Preferably, a single-pass forming process is used in the welding process of steps S4, S7, and S8;

[0026] The single-pass forming process includes the following steps:

[0027] Step A1: Match the inner diameter of the step with the outer diameter of the channel;

[0028] Step A2: Let the width of the step be b = K(0, +0.5), where K is the fillet weld leg size;

[0029] Step A3: Set the step thickness a ≥ 5 mm;

[0030] Step A4, Select welding wire specifications:

[0031] When K≤2mm, the welding wire diameter should be φ0.9-φ2.0mm;

[0032] When 2 < K ≤ 4 mm, the welding wire diameter should be φ2.0-φ4.0 mm;

[0033] When 4 < K ≤ 6 mm, the welding wire diameter should be φ3.2-φ5.0 mm;

[0034] Step A5: Weld using parameters where the weld leg size of a single fillet weld is ≥ K, forming a single pass.

[0035] Preferably, in step S8, the misalignment welding method includes the following steps:

[0036] Step B1: Draw the interference area of ​​the welding process based on the position of the multiple channels.

[0037] Step B2: Weld each hole one by one in order of decreasing interference area.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. This application adopts the method of reserving a circular step on the plate, which helps to alleviate the rapid heat loss to the thick base material during the welding process, reduce the welding current required, and thus reduce welding deformation;

[0040] 2. This application adopts an improved extended elbow welding torch, which is beneficial for operating the welding torch in small gaps in the channel, improving welding accessibility, and solving the problem that some welding positions are inaccessible in small gap channel welding.

[0041] 3. This application adopts a single-pass forming process, which can achieve fillet weld formation with a single pass, greatly improving welding efficiency;

[0042] 4. This application adopts the staggered welding method, which improves the accessibility of welding and solves the problem that the welding part of the small gap dense channel is inaccessible. Attached Figure Description

[0043] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0044] Figure 1 A schematic diagram showing the location of the reserved steps;

[0045] Figure 2 A schematic diagram of densely packed pores with small gaps;

[0046] Figure 3 This is a schematic diagram of a typical welding torch.

[0047] Figure 4 Schematic diagram of the extended elbow welding torch structure;

[0048] As shown in the figure:

[0049] Detailed Implementation

[0050] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0051] Example 1

[0052] This embodiment includes the following steps:

[0053] The first step is to use a stainless steel wire brush to remove the oxide film from the surface of the plate 2 with the pre-drilled hole 1 and the reserved circular step 21, and then wipe the surface of the plate 2 with acetone to clean it.

[0054] The second step is to use argon arc welding to spot weld and assemble the first channel 1;

[0055] The third step is to preheat the surface to be welded in the second step with an oxyacetylene flame, requiring a preheating temperature of 100-150℃.

[0056] The fourth step is to use a regular welding torch and argon arc welding machine to weld the entire circle of the first channel 1.

[0057] The fifth step is to use argon arc welding to spot weld and assemble the second channel;

[0058] Step 6: Preheat the surface to be welded in step 5 with an oxyacetylene flame, requiring a preheating temperature of 100-150℃;

[0059] Step 7: Use an extended elbow welding gun and an argon arc welding machine to weld the second duct around its entire circumference.

[0060] Step 8: Select the welding sequence of channel 1 using the optimized staggered welding method, and repeat steps 5 to 7 to complete the welding of all channels 1. Staggered welding method: Draw the interference area of ​​the welding process according to the position of the multiple channels 1; weld each channel 1 one by one in order of decreasing interference area.

[0061] More specifically:

[0062] In the first step, a stainless steel wire brush is required to remove the oxide film from the area to be welded beforehand, and assembly welding and subsequent welding should be carried out within 4 hours.

[0063] like Figure 1As shown, a circular step 21 is pre-installed on plate 2. The inner diameter of step 21 matches the outer diameter of channel 1. The step 21 is ring-shaped and integral with plate 2, and can be machined using the thickness allowance of plate 2. Single-pass forming process: The height and width of step 21 need to be determined in conjunction with the fillet weld leg size requirements. That is, under applicable welding parameters, single-pass welding can be achieved to form a weld leg that meets the requirements. No grinding is required after welding, resulting in high welding efficiency. Applicable welding parameters can be obtained through preliminary simulation tests.

[0064] Step 21 helps to mitigate the rapid heat loss to the thick base material during welding, thereby reducing the welding current at that fillet weld and decreasing welding stress and deformation. Thick base materials dissipate heat much faster than thin base materials. Welding itself requires sufficient heat to achieve metallurgical fusion between the base material and the welding material. When the base material thickness at the weld is large, a larger current is needed for welding due to the rapid heat dissipation of the aluminum alloy. Step 21 effectively thins the base material on one side of the weld, allowing direct fusion of step 21 without needing to fuse the thick plate.

[0065] In the second and fifth steps, argon arc welding is used to evenly distribute double-sided spot welding to fix the channel to be welded;

[0066] In steps three and six, the welding position needs to be repeatedly heated with an oxyacetylene flame to ensure that the preheating temperature is 100-150℃. The preheating temperature should be as high as possible to prevent the local temperature from dropping too quickly during the welding process. Oxyacetylene preheating can effectively remove moisture from the surface of the workpiece and prevent the formation of hydrogen-induced porosity.

[0067] In the fourth step, a regular welding torch is used to weld the full circle of the first duct 1 fillet weld. A single-pass forming process is used. After the front side is welded, the back side is welded. The back side welding position is overhead welding.

[0068] like Figure 3 As shown, a conventional welding torch includes a first handpiece 301, a first flow guide nozzle 302, and a first tungsten rod 303. The first tungsten rod 303 is made of lanthanum tungsten or zirconium tungsten, which has a higher melting point and helps to prevent tungsten inclusion defects in the weld during the aluminum alloy welding process.

[0069] In the seventh step, an extended elbow welding gun is used to weld the full circle fillet weld of the second duct 1. A single-pass forming process is used. After the front side is welded, the back side is welded. The back side welding position is overhead welding.

[0070] like Figure 4 As shown, the extended elbow welding torch includes a second handpiece 401, a second guide nozzle 402, a second tungsten rod 403, an extended tube 404, and a bend 405. The second tungsten rod 403 is made of lanthanum tungsten or zirconium tungsten, which has a higher melting point and helps prevent tungsten inclusion defects in the weld seam during the aluminum alloy welding process.

[0071] Compared to ordinary welding torches, the extended elbow welding torch has an extended 404 stainless steel pipe and a 405 stainless steel bend, which is beneficial for welding operations in small gap spaces and provides better accessibility.

[0072] In step eight, the welding sequence of channel 1 should be planned as accurately as possible to ensure that the interference of the channel 1 welded in the previous step is minimal and facilitates subsequent welding operations.

[0073] In the welding processes of steps four, seven, and eight, a single-pass forming process is used. The single-pass forming process is as follows:

[0074] This process is applicable to the welding of fillet welds between channel 1 and plate 2. The fillet weld leg size K≤6mm (according to the welding standard, K≤t1, generally close to the value of t1), the wall thickness of channel 1 t1≤6mm, and the thickness of plate 2 t2≥30mm.

[0075] The specific implementation steps are as follows:

[0076] 1. The inner diameter of the circular step 21 matches the outer diameter of the channel 1;

[0077] 2. The width of step 21, b, is K(0, +0.5);

[0078] 3. The thickness a of step 21 is ≥ 5mm;

[0079] 4. Select welding wire specifications:

[0080] For K≤2mm, the preferred welding wire diameter is φ0.9-φ2.0mm;

[0081] For 2 < K ≤ 4 mm, the preferred welding wire diameter is φ2.0-φ4.0 mm;

[0082] For 4 < K ≤ 6 mm, the preferred welding wire diameter is φ3.2-φ5.0 mm.

[0083] 5. Welding parameters are adopted for single-pass fillet welds with a weld leg size ≥ K, and the weld is formed in a single pass.

[0084] Specific welding parameters mainly include current, voltage, and welding speed, which can be obtained through single-pass deposition tests.

[0085] Method 1: Fabricate a single-channel 1 with wall thickness t1 and a plate 2 with thickness t2 as a simulation part, conduct a single-pass fillet weld test, optimize the welding parameters, and ensure that the weld leg size of the single-pass fillet weld is ≥K.

[0086] Note: When welding with smaller parameters, the thickness of a single weld bead can be increased by reducing the welding speed.

[0087] Example 2

[0088] Example 2 is a preferred example of Example 1.

[0089] like Figure 2 As shown, taking the welding of channel 1 and upper plate (i.e., plate 2) in the heavy water tank project as an example, plate 2 is made of aluminum alloy, grade 5052, channel 1 has a specification of φ60mm x φ50mm, upper plate thickness is 85mm, reserved circular step 21 has a height of 5mm and a width of 5.5mm, channel 1 gap is 20mm, and the welding process is as follows:

[0090] The first step is to use a stainless steel wire brush to remove the oxide film from the surface of the plate 2 with the pre-drilled hole 1 and the reserved circular step 21, and then wipe the surface of the plate 2 with acetone to clean it.

[0091] The second step is to use argon arc welding to spot weld and assemble the third channel 103;

[0092] The third step is to preheat the surface to be welded using an oxyacetylene flame, with a required preheating temperature of 100-150℃.

[0093] The fourth step is to use a regular welding torch and argon arc welding machine to weld the entire circle of the third channel 103.

[0094] The fifth step is to use argon arc welding to spot weld and assemble the second channel 102;

[0095] Step 6: Preheat the surface to be welded using an oxyacetylene flame, with a required preheating temperature of 100-150℃;

[0096] Step 7: Use an extended elbow welding gun and an argon arc welding machine to weld the entire circle of the second duct 102.

[0097] Step 8: Then, in the order of fourth channel 104, first channel 101, and fifth channel 105, repeat steps 5 to 7 to complete the welding of all channels 1, and perform visual inspection and liquid penetration inspection.

[0098] More specifically:

[0099] In the second and fifth steps, argon arc welding is used to evenly distribute double-sided spot welding with a welding current of 100-150A and a welding voltage of 10-25V to fix the channel to be welded 1.

[0100] In the fourth step, a standard welding torch is used to weld the full circle fillet weld of the third channel 103. A single-pass forming process is employed, and the single-pass forming parameters matching the reserved step 21 in the first step are as follows: (Single-pass forming process: These matching parameters were obtained through preliminary simulation tests and can ensure that the fillet weld is formed in a single pass. In the actual product welding process, due to the large number and density of channels 1, single-pass welding can significantly improve welding efficiency, reduce welding difficulty, and ensure product welding quality.)

[0101] Welding current 200-280A, welding voltage 10-25V. After welding the front side, weld the back side. The back side welding position is overhead welding.

[0102] In the seventh step, an extended elbow welding torch is used to weld the full circle fillet weld of the second duct 102. A single-pass forming process is used, with a welding current of 200-280A and a welding voltage of 10-25V. After the front side is welded, the back side is welded. The back side welding position is overhead welding.

[0103] The extension tube 404 is 10mm long, and the bend tube 405 is 1.5mm long. The extension tube 404 and the bend tube 405 are connected by threads or by welding.

[0104] The custom-designed extended elbow welding torch facilitates the welding of small gap channels and provides good accessibility.

[0105] In the eighth step, following the order of the fourth channel 104, the first channel 101, and the fifth channel 105, it can be ensured that the channel 1 welded in the previous step has minimal interference with the subsequent welding, thus facilitating the welding operation.

[0106] In steps seven and eight, select either a standard welding torch or an extended elbow welding torch based on the actual situation. A standard welding torch is suitable for locations with good accessibility, while an extended elbow welding torch is suitable for locations with poor accessibility.

[0107] The effects of using the above welding method:

[0108] 1. By using a pre-reserved circular step 21 on plate 2, the welding current required between the channel 1 and plate 2 is reduced from 320-350A to about 250A, which significantly reduces the welding current and reduces welding deformation. In addition, the reduction in welding current helps to improve the problem of tungsten inclusion caused by high current in aluminum alloy welding process and improves the quality of the weld.

[0109] 2. The customized extended elbow welding torch effectively solves the problem of poor accessibility in some positions during the welding of 5 small gap channels 1;

[0110] 3. The liquid penetration test of the weld in the five channels is qualified, the weld formation is good, and there are no defects such as cracks or slag inclusions.

[0111] 4. The welding sequence of third channel 103, second channel 102, fourth channel 104, first channel 101, and fifth channel 105 effectively ensures minimal interference and high accessibility during the welding process. (The principle of this staggered welding method is as follows: Based on the position of the channel 1, the interference area of ​​the welding process is drawn, and the channels 1 are welded one by one according to the interference area from largest to smallest. In this embodiment, the interference area of ​​the third channel 103 is the largest, followed by the interference areas of the second channel 102 and the fourth channel 104, and the interference areas of the first channel 101 and the fifth channel 105 are the smallest. Therefore, the optimal welding sequence is third channel 103, second channel 102, fourth channel 104, first channel 101, and fifth channel 105, which can ensure the highest accessibility during the welding process.)

[0112] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0113] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for welding small-gap channels in aluminum alloys, characterized in that, Includes the following steps: Step S1: Use a stainless steel wire brush to remove the oxide film from the surface to be welded on the channel (1) and the plate (2), and wipe the surface to be welded with acetone to clean it. Step S2: The first channel (1) is assembled by spot welding on the plate (2) using argon arc welding; Step S3: Preheat the surface to be welded using an oxyacetylene flame; Step S4: Use a regular welding torch argon arc welding machine to weld the entire circle of the first channel (1); Step S5: The second channel (1) is assembled by spot welding on the plate (2) using argon arc welding; Step S6: Preheat the surface to be welded using an oxyacetylene flame; Step S7: Use an extended elbow welding gun and an argon arc welding machine to weld the second duct (1) around its entire circle. Step S8: Select the welding sequence of the channel (1) using the staggered welding method and weld them. Repeat steps S5-S7 to complete the welding of all channels (1).

2. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that: In step S1, welding must be performed within 4 hours after removing the oxide film from the surface to be welded.

3. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that: In step S1, the plate (2) has a step (21) reserved for fusion with the channel (1).

4. The aluminum alloy small-gap channel welding method according to claim 3, characterized in that: The step (21) is set in a ring shape, and the inner diameter of the step (21) is adapted to the outer diameter of the channel (1).

5. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that: In steps S2 and S5, the duct to be welded is fixed by uniform double-sided spot welding using argon arc welding (1).

6. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that: In steps S3 and S6, the preheating temperature is 100-150℃.

7. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that: In step S4, the ordinary welding torch of the ordinary welding torch argon arc welding machine includes: a first hand-held section (301), a first flow guide nozzle (302), and a first tungsten rod (303); One end of the first hand-held segment (301) is fitted with a first tungsten rod (303) via a first guide nozzle (302); In step S7, the extended elbow welding torch of the extended elbow welding torch argon arc welding machine includes: a second hand-held section (401), a second guide nozzle (402), a second tungsten rod (403), an extended tube (404), and an elbow (405); One end of the second hand-held section (401) is connected to an extension tube (404), the extension tube (404) is connected to a bend tube (405), and one end of the bend tube (405) is fitted with a second tungsten rod (403) through a second guide nozzle (402).

8. The aluminum alloy small-gap channel welding method according to claim 7, characterized in that: The first tungsten rod (303) and the second tungsten rod (403) are made of lanthanum tungsten or zirconium tungsten.

9. The aluminum alloy small-gap channel welding method according to claim 3, characterized in that: A single-pass forming process is used in the welding processes of steps S4, S7, and S8. The single-pass forming process includes the following steps: Step A1: Match the inner diameter of the step (21) with the outer diameter of the channel (1); Step A2, let the width b of step (21) be K(0, +0.5), where K is the fillet weld leg size; Step A3, make the thickness a of step (21) ≥ 5mm; Step A4, Select welding wire specifications: When K≤2mm, the welding wire diameter should be φ0.9-φ2.0mm; When 2 < K ≤ 4 mm, the welding wire diameter should be φ2.0-φ4.0 mm; When 4 < K ≤ 6 mm, the welding wire diameter should be φ3.2-φ5.0 mm; Step A5: Weld using parameters where the weld leg size of a single fillet weld is ≥ K, forming a single pass.

10. The aluminum alloy small-gap channel welding method according to claim 1, characterized in that, In step S8, the misalignment welding method includes the following steps: Step B1: Draw the interference area of ​​the welding process according to the position of the multiple channels (1); Step B2: Weld each hole one by one in order of decreasing interference area (1).

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