Thin-wall aluminum alloy pipeline fillet weld TIG welding structure and method

Abstract

The invention discloses a thin-wall aluminum alloy pipeline fillet weld TIG welding structure and method, and belongs to the technical field of welding.The method comprises the steps that a boss is machined at the joint position of a fillet weld, so that a pipeline and the boss have similar heat dissipation conditions, in the TIG welding process, metal of the boss and metal of the pipeline can be molten at the same time, heat input of the weld is reduced, and welding quality is improved; the defects of air holes, cracks and the like caused by overburning of the pipeline are avoided, and the sealing performance of welding seams can be greatly improved. The method is not limited by the welding angle and the arc starting and stopping times, the compactness of the welding seam is high, and welding of the fillet welding seam of the thin-wall aluminum alloy thin pipe with the wall thickness of 0.8 mm-2. 0mm and the outer diameter of 6 mm-18 mm on the pressure-bearing container can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of welding, and relates to an aluminum alloy pipeline welding method, and in particular to a thin-walled aluminum alloy pipeline corner weld TIG welding structure and method. Background Art

[0002] Aluminum alloy welded structures have excellent comprehensive properties such as light weight, good corrosion resistance, high specific strength, fatigue strength, and easy processing. They are widely used in products in the fields of aerospace, national defense, and military. With the continuous development of model products, the requirements for aluminum alloy welded structures are becoming increasingly stringent, especially the sealing of the oil and gas pipelines inside the product is the most critical. The working pressure of the pipeline weld joint has become one of the main concerns of the design. After welding, it is necessary to ensure that the oil and gas pressure holding strength and duration in the pipe meet the design requirements. Therefore, higher and higher requirements are also put forward for the welding process of aluminum alloy pipelines.

[0003] "Overburning" means that the weld metal is heated for too long during the welding process, resulting in coarse grains, intense oxidation of the grain boundaries, slag, pores, and even peeling on the weld surface. This defect is especially caused by manual welding of all-position pipeline welds, especially when welding aluminum alloy pipelines with thin wall thickness and small diameter. This defect greatly weakens the density of the weld, resulting in micro-leakage in the weld when the product is subjected to air tightness test and oil penetration test under long-term pressure maintenance, affecting product quality.

[0004] With the continuous development of aerospace equipment, in order to meet the requirements of miniaturization and lightweight of products, the application of thin-walled aluminum alloy thin tubes is also increasing. The high-pressure and long-term working requirements of the closed cavity structure of the pipeline are becoming more and more urgent, and the requirements for the sealing type of the pipeline welds are becoming more and more stringent. CN103182590A A method for controlling the back-transmission of aluminum alloy pipeline welding is to study the butt welds with larger diameters (22mm~40mm). The method is not suitable for the welding of small-diameter angle pipes. During the argon arc welding of the angle welds of thin-tube thin-walled aluminum alloy pipelines, the welds are prone to overburning and pores, which makes it difficult to meet the requirements of airtightness tests and oil penetration tests. The use of local repair welding methods for the leakage position will increase the degree of "overburning", resulting in a situation where the more repairs, the more leaks, and the quality of pipeline welding cannot be guaranteed. Usually, the pipeline needs to be replaced. This problem limits the application of thin-walled small-diameter aluminum alloy pipeline structure products in welding production. Summary of the invention

[0005] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and provide a TIG welding structure and method for thin-walled aluminum alloy pipeline corner welds, which effectively reduces the heat input of thin-walled pipeline welds and avoids overburning of pipeline welds to form defects such as pores and cracks.

[0006] The technical solutions provided by this application are as follows:

[0007] In the first aspect, a thin-walled aluminum alloy pipeline corner weld TIG welding structure is provided, which is used for welding between the pipeline and the pressure-bearing cabin. The pressure-bearing cabin is connected with a boss, and the boss is provided with a boss hole for the pipeline to pass through. The pipeline is located in the boss hole, and a fillet is provided between the boss and the pressure-bearing cabin. The pipeline and the boss end are welded to form a corner weld joint.

[0008] The height of the boss is 3 mm to 5 mm.

[0009] The fillet R3 between the boss and the pressure-bearing cabin is 0.5-1 times the height of the boss.

[0010] The wall thickness of the boss end face is δ1=2δ0, where δ0 is the wall thickness of the pipeline.

[0011] The assembly clearance between the pipeline and the inner wall of the boss hole is less than δ0 / 4 or 0.3, whichever is smaller.

[0012] The wall thickness of the pipeline is 0.8mm-2.0mm, and the outer diameter is 6mm-18mm.

[0013] In a second aspect, a welding method for a thin-walled aluminum alloy pipeline fillet weld TIG welding structure is provided, comprising:

[0014] A boss is processed at the pipe welding position of the pressure cabin, and the boss is processed with a boss hole for the pipe to pass through;

[0015] Assemble, position and weld the pipe and boss.

[0016] The assembling, positioning and welding of the pipeline and the boss include: inserting the pipeline into the boss hole and positioning it, passing argon gas in the pipeline, and then welding.

[0017] The argon gas flow rate is (10-15) L / min.

[0018] Before assembling, positioning and welding the pipeline and the boss, the weld area of ​​the boss and the pipeline is polished and cleaned to remove the surface oxide layer, and then wiped with alcohol.

[0019] In summary, this application at least includes the following beneficial technical effects:

[0020] (1) The present invention enables the pipeline and the boss to have similar heat dissipation conditions, which can quickly form a molten pool at the weld position, reduce the heat input of the weld, avoid the formation of overburned structure in the weld, and improve the density of the weld.

[0021] (2) The present invention adopts a boss form. When the weld is melted, the boss metal can be used as the weld filler metal. When welding, no welding wire or a small amount of welding wire can be filled to complete the welding. Compared with fillet welds without bosses, when welding small-diameter pipelines, the welding gun needs to move quickly at a large angle and is combined with the filling wire, which makes the operation more difficult. The present invention does not fill the welding wire or fills a small amount of welding wire, which can greatly reduce the difficulty of operation.

[0022] (3) The present invention introduces inert gas argon into the pipeline, which helps to improve the heat dissipation conditions of the pipeline. At the same time, the internal argon environment isolates the weld from oxygen, which is beneficial to the formation of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A cross-sectional view of a weld position in one embodiment;

[0024] Figure 2 is a schematic diagram of a wall panel boss structure in one embodiment;

[0025] Figure 3 A schematic diagram of a sealed tank pipe weld in one embodiment;

[0026] The symbols in the figure represent:

[0027] 1—pressure cabin; 2—pipeline; 3—corner weld joint; 4—argon gas entering the pipeline; 5—boss; 6—oil inlet pipeline, 7—exhaust pipeline. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] In specific implementation, a Miller dynasty 700 AC / DC argon arc welding machine can be used, and argon gas uses 99.99% high-purity argon gas. The present invention is aimed at welding between a pipeline with a wall thickness of 0.8mm to 2.0mm and an outer diameter of 6mm to 18mm and a pressure container 1.

[0030] like Figure 1 and Figure 2 As shown, the present invention provides a thin-walled aluminum alloy pipeline corner weld TIG welding structure, including a structure for welding between a pipeline 2 and a pressure-bearing cabin 1, wherein the pressure-bearing cabin 1 is connected with a boss 5, the boss 5 is provided with a boss hole for the pipeline 2 to pass through, the pipeline 2 is located in the boss hole, a fillet is provided between the boss 5 and the pressure-bearing cabin 1, and the pipeline 2 and the boss 5 ends are welded to form a corner weld joint 3.

[0031] like Figure 1 and Figure 2As shown, the present invention provides a TIG welding method for a thin-walled aluminum alloy pipeline fillet weld, a TIG welding method for a thin-walled aluminum alloy pipeline fillet weld, comprising the following steps:

[0032] Step 1: Processing a boss 5 at the pipe welding position of the pressure cabin 1, wherein the boss 5 is processed with a boss hole;

[0033] When the boss 5 is processed, the boss height D is 3 mm to 5 mm, and a fillet R3 is performed between the boss heel and the pressure chamber 1, and R3 is 0.5-1 times the boss height;

[0034] When the boss is processed, the wall thickness of the boss end face is δ1=2δ0, where δ0 is the wall thickness of the pipe 2.

[0035] When processing the boss, the aperture A of the boss hole matches the outer diameter of the pipeline, and the assembly clearance is less than δ0 / 4 or 0.3mm, taking the minimum value.

[0036] Step 2: Use a wire brush to polish and clean the weld area to remove the surface oxide layer, and wipe it with alcohol, and assemble, position, and weld the pipeline. Among them, assembling, positioning, and welding the pipeline specifically includes: the pipeline includes an oil inlet pipeline 6 and an exhaust pipeline 7, assembling the oil inlet pipeline 6, the exhaust pipeline 7 and the pressure cabin 1, after argon is introduced into the oil inlet pipeline 6 for a period of time, the inflation time can be adjusted according to the size of the cabin, confirming that argon is flowing out of the exhaust pipeline 7 stably, adjusting the angle and position of the pipeline 2, and welding the end of the pipeline 2 and the boss 5 to form a fillet weld joint 3, such as Figure 3 shown.

[0037] During welding, argon gas is passed through the pipeline with a flow rate of (10-15) L / min.

[0038] A TIG welding method for fillet welds of thin-walled aluminum alloy pipelines comprises processing a boss at the position of the wall plate hole for pipeline welding so that the pipeline and the boss have similar heat dissipation conditions. During the TIG welding process, the boss and the pipeline metal can be melted at the same time to reduce the heat input of the weld. At the same time, the inert gas argon is introduced into the pipe to help the pipeline dissipate heat and isolate oxygen, avoid over-burning of the pipeline to form defects such as pores and cracks, and greatly improve the sealing of the weld.

[0039] On the contrary, if the conventional wall panel has holes without bosses, during welding, the wall panel is thicker and larger in size, and the heat dissipation conditions are much better than those of thin-walled pipes. During TIG welding, the hole position of the wall panel needs long-term arc heating to melt and form a weld pool. At this time, the pipeline is prone to welding leakage and overburning of the structure. At the same time, due to the small diameter of the pipeline, the heat is more concentrated on the pipeline during welding, and the problem of welding heat accumulation is more prominent, resulting in coarse grains, overburned structure, easy formation of pores and cracks, and affecting the quality of the weld.

[0040] The specific embodiments are as follows:

[0041] Example 1: Manual argon arc welding of 5A06 aluminum alloy pipe and ZL114A wall panel corner joint

[0042] In this embodiment, the parent material is a 5A06 aluminum alloy pipeline with a wall thickness of 1mm and an outer diameter of 6mm, the wall plate material is ZL114A aluminum alloy, the boss height is 5mm, the boss root R3 guide fillet, the boss end face wall thickness is 2mm, and the aperture is 6.15mm. The argon flow rate is 10L / min, and argon is passed for 5min before welding. The welding wire is made of 5A06 material and the wire diameter is 1.6mm. The welding current is 38A, and the argon flow rate of the welding gun is 7L / min. The final fillet weld is well formed and the transition is smooth. After X-ray detection, the weld has no defects such as incomplete penetration, incomplete fusion, and pores, and the back is slightly reversed, which can meet the requirements of 4mm diameter steel balls in QJ919A-1998. After 0.1MPa pressure maintenance for 30min airtightness detection, the weld has no leakage. After 0.085MPa pressure maintenance for 16h oil penetration detection, the weld has no leakage.

[0043] Example 2: Manual argon arc welding of 5A06 aluminum alloy pipe and 5A06 wall panel fillet

[0044] In this embodiment, the parent material is a 5A06 aluminum alloy pipeline with a wall thickness of 1.5mm and an outer diameter of 10mm, the wall plate material is 5A06 aluminum alloy, the boss height is 5mm, the boss root R3 guide fillet, the boss end face wall thickness is 3mm, and the aperture is 10.25mm. The argon flow rate is 10L / min, and argon is passed for 5min before welding. The welding wire is made of 5A06 material and the wire diameter is 1.6mm. The welding current is 42A, and the argon flow rate of the welding gun is 8L / min. The final fillet weld is well formed and the transition is smooth. After X-ray detection, the weld has no defects such as incomplete penetration, incomplete fusion, and pores, and the back is slightly reversed, which can meet the requirements of 8mm diameter steel balls in QJ919A-1998. After 0.1MPa pressure maintenance for 30min airtightness detection, the weld has no leakage. After 0.085MPa pressure maintenance for 16h oil penetration detection, the weld has no leakage.

[0045] Example 3: Manual argon arc welding of 5083 aluminum alloy pipe and 5A06 wall panel corner joint

[0046] In this embodiment, the parent material is a 5083 aluminum alloy pipeline with a wall thickness of 2.0mm and an outer diameter of 18mm, the wall plate material is 5A06 aluminum alloy, the boss height is 5mm, the boss root R3 guide fillet, the boss end face wall thickness is 4mm, and the aperture is 18.3mm. The argon flow rate is 15L / min, and argon is passed for 5min before welding. The welding wire is made of 5A06 material and the welding wire diameter is 1.6mm. The welding current is 48A, and the argon flow rate of the welding gun is 10L / min. The final fillet weld is well formed and the transition is smooth. After X-ray detection, the weld has no defects such as incomplete penetration, incomplete fusion, and pores, and the back is slightly reversed, which can meet the requirements of 16mm diameter steel balls in QJ919A-1998. After 0.1MPa pressure maintenance for 30min airtightness detection, the weld has no leakage. After 0.085MPa pressure maintenance for 16h oil penetration detection, the weld has no leakage.

[0047] Example 4: Manual argon arc welding of 5A02 aluminum alloy pipe and 6005A wall panel corner joint

[0048] In this embodiment, the parent material is a 5A02 aluminum alloy pipeline with a wall thickness of 1.0mm and an outer diameter of 10mm, the wall plate material is 6005A aluminum alloy, the boss height is 5mm, the boss root R3 guide fillet, the boss end face wall thickness is 2mm, and the aperture is 10.2mm. The argon flow rate is 10L / min, and argon is passed for 5min before welding. The welding wire is made of 5A06 material and the welding wire diameter is 1.6mm. The welding current is 38A, and the argon flow rate of the welding gun is 7L / min. The final fillet weld is well formed and the transition is smooth. After X-ray detection, the weld has no defects such as incomplete penetration, incomplete fusion, and pores, and the back is slightly reversed, which can meet the requirements of 8mm diameter steel balls in QJ919A-1998. After 0.1MPa pressure maintenance for 30min airtightness detection, the weld has no leakage. After 0.085MPa pressure maintenance for 16h oil penetration detection, the weld has no leakage.

[0049] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0050] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A thin-walled aluminum alloy pipeline fillet weld TIG welding structure, used for welding between a pipeline (2) and a pressure cabin (1), characterized in that: The pressure-bearing cabin (1) is connected to a boss (5), the boss (5) is provided with a boss hole for the pipeline (2) to pass through, the pipeline (2) is located in the boss hole, a rounded corner is provided between the boss (5) and the pressure-bearing cabin (1), and the pipeline (2) and the boss (5) are welded at their ends to form a fillet weld joint (3).

2. A thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to claim 1, characterized in that: The height of the boss (5) is 3 mm to 5 mm.

3. A thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to claim 1, characterized in that: The fillet R3 between the boss (5) and the pressure-bearing cabin (1) is 0.5 to 1 times the height of the boss (5).

4. A thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to claim 1, characterized in that: The end face wall thickness of the boss (5) is δ1=2δ0, wherein δ0 is the wall thickness of the pipeline (2).

5. The thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to claim 1, characterized in that: The assembly clearance between the pipeline (2) and the inner wall of the boss hole is less than δ0 / 4 or 0.3, whichever is smaller.

6. The thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to claim 1, characterized in that: The pipe (2) has a wall thickness of 0.8 mm to 2.0 mm and an outer diameter of 6 mm to 18 mm.

7. A welding method for a thin-walled aluminum alloy pipeline fillet weld TIG welding structure according to any one of claims 1 to 6, characterized in that: include: A boss (5) is machined at a welding position of a pipeline (2) of the pressure-bearing cabin (1), and a boss hole for the pipeline (2) to pass through is machined on the boss (5); The pipeline (2) and the boss (5) are assembled, positioned and welded.

8. The welding method according to claim 7, characterized in that: The assembly, positioning and welding of the pipeline (2) and the boss (5) comprises: inserting the pipeline (2) into the boss hole and positioning it, passing argon gas into the pipeline (2), and then welding.

9. The welding method according to claim 8, characterized in that: The argon gas flow rate is (10-15) L / min.

10. The welding method according to claim 7, characterized in that: Before assembling, positioning and welding the pipeline (2) and the boss (5), the weld area of ​​the boss (5) and the pipeline (2) is polished and cleaned to remove the surface oxide layer, and then wiped with alcohol.

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