A manual TIG welding method for longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components

Abstract

The present invention discloses a manual TIG welding method for longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components, which relates to an aluminum alloy TIG welding method. The main steps of the present invention are: cone forming of the workpiece to be welded; cleaning; positioning welding of the workpiece to be welded; welding of longitudinal butt joints of the workpiece to be welded; assembly; preheating; positioning welding; welding; post-weld annealing; and testing. The present invention achieves reliable welding between 5A06 aluminum alloys, reasonably selects a small linear energy input, and adopts symmetrical staggered back-welding welding to control the welding temperature and the overall temperature of the workpiece to be uniform, so that the workpiece is free of deformation and a high-quality weld is obtained. The welding method of the present invention is used for manual TIG welding of longitudinal circumferential seams of thin-walled cylindrical aluminum alloy cylinders and cylinders and flanges, and manual TIG welding of longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy cylinders and cylinders and flanges, and has a reference and promotion role.

Description

Technical Field

[0001] The invention relates to a TIG welding method for an aluminum alloy, in particular to a manual TIG welding method for butting longitudinal circumferential seams of a thin-walled frustum-shaped aluminum alloy component. Background Art

[0002] As a material joining technology for aluminum and aluminum alloys, welding is increasingly demanding advancements in welding processes for these materials, driven by the increasing demands for larger, more complex, lighter, and more cost-effective product structures. 5A06 aluminum alloy, a non-heat-treatable aluminum alloy in the aluminum-magnesium family, offers excellent corrosion resistance, fracture toughness, and weldability. It boasts excellent overall performance and is widely used in aerospace, containers, and other fields, making it an ideal lightweight material. Achieving high-quality and reliable aluminum alloy welding processes, particularly in military applications, has long been a major focus of research. In the design of frustum-shaped aluminum alloy components, 5A06 aluminum alloy with a thickness of approximately 4.0 mm is typically used, with longitudinal welds of varying diameters and circumferential welds between the cylinder and flange. However, in actual production, the components are relatively long, the cylinder is thin-walled, and has poor rigidity. Without a locking bottom butt joint, the interaction between the multiple longitudinal and circumferential welds makes it difficult to control overall deformation, leading to deformation in the welded component and failing to meet the product's design requirements.

[0003] With the development of welding technology, more and more effective welding methods, such as laser welding and pulsed gas metal arc welding, are gradually being applied to aluminum alloy welding. However, for enterprises, production costs are usually the primary consideration. The controllable pulse current of pulsed TIG welding heats the workpiece, and the entire welding process is an intermittent heating process. This can reduce the effective value of the welding current, effectively control the heat input of the weldment, and reduce welding deformation, making it suitable for thin-walled shell welding. In addition, the use of pulsed current also helps stir the aluminum alloy weld pool, promotes molten pool flow, and allows gas to escape faster, thereby reducing weld porosity defects.

[0004] Therefore, it is necessary and practical to invent a manual pulse TIG welding method for the longitudinal circumferential seam of thin-walled frustum-shaped aluminum alloy components by utilizing the characteristics of pulse TIG welding and combining the structural characteristics of the product. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a manual TIG welding method for the longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components, so as to solve the welding technical difficulties of a large number of pores and even welding deformation in the longitudinal circumferential seams of thin-walled frustum-shaped 5A06 aluminum alloy components, so as to ensure that the welded joints are well-formed, free of welding defects, have good mechanical properties, and meet product design requirements.

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is: a manual TIG welding method for butt-jointing longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components, which adopts the method of spot welding, bottom welding, and cover welding from the middle to the two ends of the longitudinal seam and combines the segmented back-welding method for welding and the symmetrical segmented back-welding method for staggered welding of each circumferential seam, and performs manual TIG welding, including the following steps:

[0007] (1) Cone forming of parts A and B with 5A06 as the material to be welded: the parts A and B to be welded are processed into a single V-shaped groove with no blunt edge and a groove angle of 30°, and then parts A and B are rolled into a cone shape by a plate rolling machine;

[0008] (2) Cleaning: After the cone is formed, use a wire brush to clean all the surfaces within the groove of the welded parts, the surface within 30mm on both sides of the groove, and the welding wire to remove oil and rust. Grind to remove oil, rust, burrs, moisture, oxide scale and other debris until the metallic luster is exposed. Confirm that there are no defects in the welding part and within 30mm on both sides.

[0009] (3) Position welding of parts A and B: Place the cleaned parts to be welded horizontally on the roller bracket. Use manual TIG welding. First, determine the center point for positioning welding along the axial direction in the groove at the contact point of the cone parts A and B. Then, divide the weld point into two parts symmetrically around the center point for spot welding. The weld points are evenly distributed. The weld length is 3mm to 4mm. The welding direction is from the middle to the two ends. Confirm that there are no cracks in the weld and no deformation defects in the workpiece after welding.

[0010] (4) Welding the longitudinal butt joint of parts A and B: Use the left welding method, place the blank of the workpiece to be welded on the roller bracket, always keep the welding part in a horizontal position, and weld the two sides of the weld seam bisected by the center point in a segmented symmetrical alternating back-welding method. When performing the bottom welding, the arc should be raised before welding to preheat the groove to 100℃±10℃. When the preheating temperature drops to 60℃, start the segmented symmetrical alternating back-welding, that is, divide the weld joint to be welded into several sections of the same length, and keep each section of the joint at the center. With the center point as the symmetrical center, perform symmetrical and alternating back-welding in sections towards the center point. After each section is welded, wait for a while before welding the next section, and repeat the process to ensure that the temperature of the blank to be welded is not higher than 60°C. Then perform the cover welding. The welding sequence and method are the same as the base welding. The tungsten electrode should be cerium tungsten electrode with a diameter of 2.4mm. The welding should be cold at the beginning, with the current at the upper limit and the welding gun not swinging. Each section should be welded continuously without stopping. After each section is welded, ensure that the temperature of the next section is not higher than 60°C before welding.

[0011] (5) Assembly: Assemble the flange parts C, D and E with the material to be welded being 5A06 with the welded parts A and B through welding fixtures to ensure that the workpieces are not deformed;

[0012] (6) Preheating: Preheat the assembled flange parts C, D and E to be welded and the welded parts A and B as a whole before welding. The preheating temperature is 100℃±10℃ and the preheating time is 30min~40min. After preheating, the oxide scale and debris on the welding parts should be cleaned;

[0013] (7) Position welding: Spot weld the circumferential butt joints of the flange parts C, D and E to be welded and the parts A and B to be welded evenly along the circumferential direction with the center of the circle as the symmetric center. The weld length is 3mm to 4mm. Confirm that there are no cracks in the weld and no deformation defects in the workpiece after welding.

[0014] (8) Welding: Weld the circumferential butt joints between the flange parts C, D and E to be welded and the parts A and B to be welded: Use the left welding method, place the assembly of parts to be welded on the roller frame, and evenly divide the butt joint into several sections of equal length with the circle as the center of symmetry. Use the segmented symmetrical alternating back-welding method for welding, that is, weld one section first, and then weld a symmetrical section with the center of the circle as the center of symmetry. The starting point of each welding section is the end point of the previous section weld. After each section is welded, there is a gap before welding the next section weld. Repeat the welding process to ensure that the temperature of the blank of the parts to be welded is not higher than 60℃; then perform the filling welding. The welding sequence and welding method are the same as the bottom welding; according to the welding of parts B and E , C and A, D and B, D and A, carry out the bottom welding between the four parts of the workpiece in this order. Carry out half of the bottom welding of each part first, and then complete the bottom welding of the remaining parts in the order of each part after all the welding is completed. Pay attention to the heat preservation of the local workpiece during the whole process, and then carry out the cover welding. The welding sequence and welding method are the same as the bottom welding. The tungsten electrode should be cerium tungsten electrode with a diameter of 2.4mm. The welding gun does not swing, and each section is welded continuously without stopping. After each section is welded, ensure that the temperature of the next section before welding is not higher than 60℃; the welding environment temperature is not lower than 10℃, the relative humidity is not more than 75%, and the air flow is not more than 2m / s;

[0015] (9) Post-weld annealing: After welding, the welded components are cooled naturally to room temperature. The post-weld annealing temperature is 280℃±5℃, the holding time is 0.5h, and then the components are cooled to 60℃ and then air-cooled to room temperature.

[0016] (10) Inspection: Use X-ray flaw detection to inspect welds. No cracks or pores are allowed on the weld surface. Visual inspection should be conducted to ensure that there are no pits or undercut defects.

[0017] In step (1), the thickness of 5A06 parts A and B is 4 mm to 5 mm, the diameter of the small end of the frustum is 300 mm to 600 mm, the diameter of the large end of the frustum is 500 mm to 800 mm, the length of the frustum is 650 mm to 1100 mm, and the total length of the assembly is 1800 mm to 2000 mm.

[0018] In the step (3), a cerium tungsten electrode should be used for welding, the tungsten electrode diameter is 2.4 mm, the pulse peak current is 130A to 140A, the pulse base current is 20A, the pulse frequency is 5 Hz, the duty cycle is 50%, the welding wire diameter is 2.0 mm, the welding wire grade is ER5356, the gas flow rate is 10 L / min to 12 L / min; and the argon purity is not less than 99.99%.

[0019] In the step (4), the base welding is performed by manual TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, and the argon purity is 99.99%; the pulse peak current is 120 A to 130 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, and the welding speed is 7 cm / min; the cap welding is performed by pulse TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, the argon purity is 99.99%, the pulse peak current is 130 A to 140 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, the welding speed is 7 cm / min, and the weld height after welding is 0.5 mm.

[0020] In step (7), the tungsten electrode should be a cerium tungsten electrode with a diameter of 2.4 mm, a welding current of 130 A to 140 A, a welding wire diameter of 2.0 mm, a welding wire grade of ER5356, a gas flow rate of 10 L / min to 12 L / min, and an argon purity of not less than 99.99%.

[0021] The advantages of the welding method of the present invention are:

[0022] By giving full play to the advantages of manual pulse TIG welding, it can ensure that the welds between 5A06 aluminum alloys are well fused. After radiographic inspection, no pores or cracks were found in the welds and heat-affected zones, and the welds are well formed.

[0023] Reasonable selection of small linear energy input, the use of center-symmetrical staggered back-welding to control the welding temperature and the overall temperature of the workpiece to uniformize the workpiece without deformation and obtain high-quality welds.

[0024] The welding method of the present invention is suitable for the manual TIG welding method of the longitudinal circumferential seam of thin-walled frustum-shaped aluminum alloy components, and can be extended to the manual TIG welding method of the longitudinal circumferential seam of thin-walled cylindrical aluminum alloy cylinders and the cylinder and flange butt joints, the manual TIG welding of the longitudinal circumferential seam of thin-walled frustum-shaped aluminum alloy cylinders and the cylinder and flange butt joints, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram showing the welding of 5A06 parts A, B, C, D, and E of the present invention.

[0026] In the figure: 1-piece A, 2-piece B, 3-piece C, 4-piece D, 5-piece E, 6-weld I, 7-weld II, 8-weld III, 9-weld IV, 10-weld V, 11-weld VI. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is described clearly and completely below with reference to the accompanying drawings and specific embodiments.

[0028] Reference Figure 1 As shown, a manual TIG welding method for butt-jointing longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components is provided. The method includes spot welding, bottom welding, and cover welding from the middle to both ends of the longitudinal seam, combined with a segmented back-welding method, and staggered welding of each circumferential seam using a symmetrical segmented back-welding method. The manual TIG welding includes the following steps:

[0029] (1) Cone forming of parts A1 and B2 made of 5A06 to be welded: the parts A1 and B2 to be welded are processed into a single V-shaped groove with no blunt edge and a groove angle of 30°, and then parts A1 and B2 are rolled into a cone shape by a plate rolling machine;

[0030] (2) Cleaning: After the cone is formed, use a wire brush to clean all the surfaces within the groove of the welded parts, the surface within 30mm on both sides of the groove, and the welding wire to remove oil and rust. Grind away oil, rust, burrs, moisture, oxide scale and other debris until the metallic luster is exposed. Confirm that there are no defects in the welding part and within 30mm on both sides.

[0031] (3). Positioning welding of parts A1 and B2: The cleaned parts to be welded are always placed horizontally on the roller bracket, and manual TIG welding is adopted. The center point is first determined for positioning welding along the axial direction in the groove of the contact between the cone parts A1 and B2. Then the weld point is symmetrically divided into two parts with the center point for spot welding. The weld points are evenly distributed. The longitudinal positioning spot welding length of weld I 6 and weld II 7 is 3mm to 4mm. The welds are formed by rolling cones on parts A1 and B2. For the longitudinal fixed spot welds of 7, the welding direction is from the middle to the two ends. The tungsten electrode should be a cerium tungsten electrode with a diameter of 2.4mm, a pulse peak current of 130A to 140A, a pulse base current of 20A, a pulse frequency of 5Hz, a duty cycle of 50%, a welding wire diameter of 2.0mm, a welding wire grade of ER5356, and a gas flow rate of 10L / min to 12L / min. The purity of argon gas should be no less than 99.99%. After welding, confirm that the longitudinal fixed spot welds of welds I 6 and II 7 are free of cracks and workpiece deformation.

[0032] (4). Welding of the longitudinal butt joint of parts A1 and B2: adopt the left welding method; place the blank of the workpiece to be welded on the roller bracket, always keep the welding part in a horizontal position, and make weld seams Ⅰ6 or Ⅱ7 on both sides of the center point. The weld seams are longitudinal positioning spot welding, and then the base weld and cover weld are made. They are welded by segmented symmetrical alternating back-welding. When performing the base welding, the arc should be raised before welding to preheat the groove to 100℃±10℃. When the preheating temperature drops to 60℃, the segmented symmetrical alternating back-welding is started, that is, the weld joint to be welded is divided into several sections of the same length. Each section of the joint is kept symmetrical with the center point as the center and is welded in a segmented symmetrical alternating back-welding direction towards the center point. After each section is welded, there is a gap and the next section of the base weld is welded. This weld is weld seam Ⅰ6 or weld seam Ⅱ. 7. For the base weld, perform reciprocating welding in sequence to ensure that the temperature of the blank to be welded is not higher than 60°C; then perform the cover welding, and the welding sequence and method are the same as the base welding; the tungsten electrode should be a cerium tungsten electrode with a tungsten electrode diameter of 2.4mm; the welding starts with cold welding, the current is at the upper limit, the welding gun does not swing, and each section is welded continuously without stopping. After each section is welded, ensure that the temperature of the next section before welding is not higher than 60°C;

[0033] (5) Assembly: Assemble flange parts C 3, D 4 and E 5, whose material is 5A06, with parts A 1 and B 2 after welding, through welding fixtures to ensure that the workpieces are not deformed;

[0034] (6) Preheating: Preheat the assembled flange parts C3, D4 and E5 and the welded parts A1 and B2 as a whole before welding. The preheating temperature is 100℃±10℃ and the preheating time is 30min~40min. After preheating, clean the welded parts of ...

[0035] (7). Positioning welding: The circumferential butt joints of the flange parts C3, D4 and E5 to be welded and the welded parts A1 and B2 are evenly spot welded along the circumferential direction with the center of the circle as the symmetric center. The length of the circumferential positioning spot welds of weld III 8, weld IV 9, weld V 10 and weld VI 11 is 3mm to 4mm. These welds are weld III 8, weld VI 9, weld V 10 and weld VI of flange parts C3, D4 and E5 and the welded parts A1 and B2 respectively. For the circumferential positioning spot weld of 11, the tungsten electrode should be a cerium tungsten electrode with a tungsten electrode diameter of 2.4mm, a welding current of 130A to 140A, a welding wire diameter of 2.0mm, a welding wire grade of ER5356, and a gas flow rate of 10L / min to 12L / min; the argon purity should be no less than 99.99%; after welding, confirm that the circumferential positioning spot welds of weld III 8, weld IV 9, weld V 10, and weld VI 11 are free of cracks and workpiece deformation.

[0036] (8) Welding: Weld the circumferential butt joints between the flange parts C3, D4 and E5 to be welded and the parts A1 and B2 to be welded: adopt the left welding method; place the assembly of parts to be welded on the roller frame, divide the butt joint into several sections of equal length with the circle as the center of symmetry, and weld them in a segmented symmetrical alternating welding method, that is, weld one section first, and then weld a symmetrical section with the center of the circle as the center of symmetry. The starting point of each welding section is the end point of the previous section's base weld, which is the base weld of weld III 8, weld IV 9, weld V 10, and weld VI 11. After each section is welded, there is an interval before welding the next section's base weld, which is weld III 8, weld IV 9, weld V 10, and weld VI. 11, the backing weld is welded back and forth in sequence to ensure that the temperature of the blank to be welded is not higher than 60℃; then filler welding is carried out, and the welding sequence and welding method are the same as the backing welding; in the order of piece B 2 and piece E 5, piece C 3 and piece A 1, piece D 4 and piece B 2, piece D 4 and piece A 1, the backing welding is carried out between the four parts of the workpiece. For each part, half of the sections are welded first. After all the welding is completed, the backing welding of the remaining sections is completed in the order of each section. During the whole process, pay attention to the heat preservation of the local workpiece, and then carry out the cover welding. The welding sequence and welding method are the same as the backing welding; the tungsten electrode should be cerium tungsten electrode with a tungsten electrode diameter of 2.4mm; the welding gun does not swing, and each section is welded continuously without stopping. After each section is welded, ensure that the temperature of the next section before welding is not higher than 60℃; the welding environment temperature is not lower than 10℃, the relative humidity is not more than 75%, and the air flow is not more than 2m / s;

[0037] (9) Post-weld annealing: After welding, the welded components are cooled naturally to room temperature. The post-weld annealing temperature is 280℃±5℃, the holding time is 0.5h, and then the components are cooled to 60℃ and then air-cooled to room temperature.

[0038] (10): Inspection: X-ray flaw detection method is used to inspect the welds. The welds are the cover welds of welds I 6, welds II 7, welds III 8, welds IV 9, welds V 10, and welds VI 11. The cover welds of welds I 6, welds II 7, welds III 8, welds IV 9, welds V 10, and welds VI 11 are not allowed to have cracks or pores. Visual inspection shows that there are no defects such as pits and undercuts.

[0039] According to one embodiment of the present invention, in step (1), the thickness of the 5A06 piece A1 and piece B2 is 4mm to 5mm, the diameter of the small end of the frustum is 300mm to 600mm, the diameter of the large end of the frustum is 500mm to 800mm, the length of the frustum is 650mm to 1100mm, and the total length of the assembly is 1800mm to 2000mm.

[0040] According to one embodiment of the present invention, in step (4), the base welding is performed by manual TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, and the argon purity is 99.99%; the pulse peak current is 120 A to 130 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, and the welding speed is 7 cm / min; the cap welding is performed by pulse TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, and the argon purity is 99.99%; the pulse peak current is 130 A to 140 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, and the welding speed is 7 cm / min; after welding, the cap welding seam height is 0.5 mm, and the weld is the weld after the cap welding of weld I6 and weld II7.

[0041] The above implementation method stabilizes the welding quality of the product and avoids the problem of deformation of the welded workpiece caused by the mutual influence of multiple longitudinal and circumferential welds designed, which makes it difficult to control the overall deformation of the workpiece due to the long total length of the product components, the thin-walled cylinder, poor rigidity, and the lack of a locking bottom butt joint. The requirements for dimensional accuracy and shape accuracy are very high.

Claims

1. A manual TIG welding method for butt welding longitudinal circumferential seams of thin-walled frustum-shaped aluminum alloy components, characterized by: The longitudinal seam is welded from the middle to both ends by spot welding, bottom welding, and cover welding, and the welding is carried out in combination with the segmented back-welding method, and each circumferential seam is welded in a staggered manner by the symmetrical segmented back-welding method, and the manual TIG welding is carried out, including the following steps: (1) Cone forming of parts A and B with 5A06 as the material to be welded: the parts A and B to be welded are processed into a single V-shaped groove with no blunt edge and a groove angle of 30°, and then parts A and B are rolled into a cone shape by a plate rolling machine; (2) Cleaning: After the cone is formed, use a wire brush to clean all the surfaces within the groove of the welded parts, the surface within 30mm on both sides of the groove, and the welding wire to remove oil and rust. Grind to remove oil, rust, burrs, moisture, oxide scale and other debris until the metallic luster is exposed. Confirm that there are no defects in the welding part and within 30mm on both sides. (3) Position welding of parts A and B: Place the cleaned parts to be welded horizontally on the roller bracket. Use manual TIG welding. First, determine the center point for positioning welding along the axial direction in the groove at the contact point of the cone parts A and B. Then, divide the weld point into two parts symmetrically around the center point for spot welding. The weld points are evenly distributed. The weld length is 3mm to 4mm. The welding direction is from the middle to the two ends. Confirm that there are no cracks in the weld and no deformation defects in the workpiece after welding. (4) Welding the longitudinal butt joint of parts A and B: Use the left welding method, place the blank of the workpiece to be welded on the roller bracket, always keep the welding part in a horizontal position, and weld the two sides of the weld seam bisected by the center point in a segmented symmetrical alternating back-welding method. When performing the bottom welding, the arc should be raised before welding to preheat the groove to 100℃±10℃. When the preheating temperature drops to 60℃, start the segmented symmetrical alternating back-welding, that is, divide the weld joint to be welded into several sections of the same length, and keep each section of the joint at the center. With the center point as the symmetrical center, perform symmetrical and alternating back-welding in sections towards the center point. After each section is welded, wait for a while before welding the next section, and repeat the process to ensure that the temperature of the blank to be welded is not higher than 60°C. Then perform the cover welding. The welding sequence and method are the same as the base welding. The tungsten electrode should be cerium tungsten electrode with a diameter of 2.4mm. The welding starts with cold welding, the current is at the upper limit, the welding gun does not swing, and each section is welded continuously without stopping. After each section is welded, ensure that the temperature of the next section is not higher than 60°C before welding. (5) Assembly: Assemble the flange parts C, D and E with the material to be welded being 5A06 with the welded parts A and B through welding fixtures to ensure that the workpieces are not deformed; (6) Preheating: Preheat the assembled flange parts C, D and E to be welded and the welded parts A and B as a whole before welding. The preheating temperature is 100℃±10℃ and the preheating time is 30min~40min. After preheating, the oxide scale and debris on the welding parts should be cleaned; (7) Position welding: Spot weld the circumferential butt joints of the flange parts C, D and E to be welded and the parts A and B to be welded evenly along the circumferential direction with the center of the circle as the symmetric center. The weld length is 3mm to 4mm. Confirm that there are no cracks in the weld and no deformation defects in the workpiece after welding. (8) Welding: Weld the circumferential butt joints between the flange parts C, D and E to be welded and the parts A and B to be welded: Use the left welding method, place the assembly of parts to be welded on the roller frame, and evenly divide the butt joint into several sections of equal length with the circle as the center of symmetry. Use the segmented symmetrical alternating back-welding method for welding, that is, weld one section first, and then weld a symmetrical section with the center of the circle as the center of symmetry. The starting point of each welding section is the end point of the previous section weld. After each section is welded, there is a gap before welding the next section weld. Repeat the welding process to ensure that the temperature of the blank of the parts to be welded is not higher than 60℃; then perform the filling welding. The welding sequence and welding method are the same as the bottom welding; according to the welding of parts B and E , C and A, D and B, D and A, carry out the bottom welding between the four parts of the workpiece in this order. Carry out half of the bottom welding of each part first, and then complete the bottom welding of the remaining parts in the order of each part after all the welding is completed. Pay attention to the heat preservation of the local workpiece during the whole process, and then carry out the cover welding. The welding sequence and welding method are the same as the bottom welding. The tungsten electrode should be cerium tungsten electrode with a diameter of 2.4mm. The welding gun does not swing, and each section is welded continuously without stopping. After each section is welded, ensure that the temperature of the next section before welding is not higher than 60℃; the welding environment temperature is not lower than 10℃, the relative humidity is not more than 75%, and the air flow is not more than 2m / s; (9) Post-weld annealing: After welding, the welded components are cooled naturally to room temperature. The post-weld annealing temperature is 280℃±5℃, the holding time is 0.5h, and then the components are cooled to 60℃ and then air-cooled to room temperature. (10) Inspection: Use X-ray flaw detection to inspect welds. No cracks or pores are allowed on the weld surface. Visual inspection should be conducted to ensure there are no pits or undercut defects. In step (1), the thickness of 5A06 parts A and B is 4mm to 5mm, the diameter of the small end of the frustum is 300mm to 600mm, the diameter of the large end of the frustum is 500mm to 800mm, the length of the frustum is 650mm to 1100mm, and the total length of the assembly is 1800mm to 2000mm.

2. A method for manual TIG welding of longitudinal annular seams of thin-walled frustum-shaped aluminum alloy components according to claim 1, characterized in that In the step (3), the tungsten electrode should be a cerium tungsten electrode with a diameter of 2.4 mm, a pulse peak current of 130 A to 140 A, a pulse base current of 20 A, a pulse frequency of 5 Hz, a duty cycle of 50%, a welding wire diameter of 2.0 mm, a welding wire grade of ER5356, a gas flow rate of 10 L / min to 12 L / min, and an argon purity of not less than 99.99%.

3. A method for manual TIG welding of longitudinal annular seams of thin-walled frustum-shaped aluminum alloy components according to claim 1, characterized in that In the step (4), the base welding is performed by manual TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, and the argon purity is 99.99%; the pulse peak current is 120 A to 130 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, and the welding speed is 7 cm / min; the cap welding is performed by pulse TIG welding, the welding wire is ER5356, the welding wire diameter is 2.0 mm, the gas flow rate is 10 L / min to 11 L / min, the argon purity is 99.99%, the pulse peak current is 130 A to 140 A, the pulse base current is 20 A, the pulse frequency is 5 Hz, the duty cycle is 50%, the welding speed is 7 cm / min, and the weld excess height after welding is 0.5 mm.

4. A method for manual TIG welding of longitudinal annular seams of thin-walled frustum-shaped aluminum alloy components according to claim 1, characterized in that In the step (7), the tungsten electrode should be a cerium tungsten electrode with a diameter of 2.4 mm, a welding current of 130 A to 140 A, a welding wire diameter of 2.0 mm, a welding wire grade of ER5356, a gas flow rate of 10 L / min to 12 L / min, and an argon purity of not less than 99.99%.

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