Electron beam annular welding method for thin-wall shell aluminum alloy gas cylinder

Abstract

The invention relates to the technical field of welding processes, and discloses an electron beam annular welding method for a thin-wall shell aluminum alloy gas cylinder, which comprises the steps of cleaning, manual scale scraping, drying, assembling, circumferential seal welding, central position adjustment, annular welding, cooling, cylinder taking and the like. The elastic adjustable fastening tool is used for fastening the hemispherical shell-shaped components on the two sides, it is guaranteed that the gap between the two hemispherical shell-shaped components is uniform, therefore, welding deformation of the two thin-wall shells is reduced, the welding seam quality is guaranteed, electron beam welding process parameters are adjusted through the method, and nail point air holes generated in electron beam welding seams are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of welding technology, and in particular to an electron beam annular welding method for a thin-wall shell aluminum alloy gas cylinder. Background Art

[0002] Vacuum electron beam welding (EBM for short) technology is widely used in important industries and defense fields such as aerospace, automobile manufacturing, etc. Vacuum electron beam welding technology has the advantages of fast welding speed, small deformation, and small heat-affected zone. Welding in a vacuum eliminates the influence of N2, O2, etc. in the atmosphere on welding, which is beneficial to improve the purity of the weld and improve the mechanical properties of the weld.

[0003] Electron beam welding is a welding process that uses an electron beam as a heat source. When the cathode in the electron beam generator is heated to a certain temperature, electrons escape. The electrons are accelerated in a high-voltage electric field and focused by an electromagnetic lens to form an electron beam with extremely high energy density. When the electron beam bombards the welding surface, most of the kinetic energy of the electrons is converted into heat energy, causing the metal at the joint of the weld to melt. When the weld moves, a continuous weld is formed at the joint of the weld. For a vacuum electron beam welder, the workpiece to be welded is placed in a vacuum chamber and is generally clamped on a workbench that can move linearly or rotate.

[0004] The ultra-thin-wall aluminum alloy gas cylinder is made of two hemispherical shell-shaped parts for circular welding. Since the material of the gas cylinder is aluminum alloy 5A06, the magnesium content is between 5.8-6.8; the thickness of the two hemispherical shells is 0.8mm and the thickness of the lock bottom is 1.5mm. During welding, the back of the weld cannot be welded through because the welding material is too thin and the penetration is too small. There are two technical problems: First, due to the properties of the material, nail tip pore welding defects are prone to occur during electron beam welding; Second, the weld after the two hemispherical thin-walled shells are synthesized is uneven or the width is too large, which may cause local overheating on the back of the weld and produce weld bead ablation. Based on the technical defects of the prior art, the inventor has developed an electron beam circular welding method for ultra-thin-wall aluminum alloy gas cylinders, which can well solve the problems of the above-mentioned prior art. Summary of the invention

[0005] The purpose of the present invention is to provide an electron beam annular welding method for a thin-walled shell aluminum alloy gas cylinder to solve the technical problems in the prior art.

[0006] In order to achieve the above object, the present invention provides an electron beam annular welding method for a thin-walled shell aluminum alloy gas cylinder, comprising the following steps:

[0007] Using an elastically adjustable fastening tool, two hemispherical shell-shaped components are butt-jointed and assembled with a lock bottom to obtain an assembly;

[0008] Placing the assembly in a vacuum electron beam welding device and performing circumferential sealing welding;

[0009] Re-adjusting the electron beam position to the center of the weld, and performing annular welding on the sealed assembly;

[0010] The annularly welded assembly is vacuum cooled in the vacuum chamber, and after cooling, the hatch is opened and taken out to obtain the thin-walled aluminum alloy gas cylinder.

[0011] Preferably, the elastically adjustable fastening tool comprises two relatively arranged U-shaped clamping members and an elastic member arranged between the two U-shaped clamping members.

[0012] Preferably, the vacuum degree in the vacuum electron beam welding equipment is 3×10 -4 mbar.

[0013] Preferably, the welding process parameters of the circumferential sealing welding are electron beam current 3-5mA, circular wave or triangular wave, acceleration voltage 30-60kv, welding speed 800-1200mm / min, electron beam scanning frequency 100-300HZ, and electron beam scanning amplitude 2-5mA.

[0014] Preferably, re-adjusting the electron beam position to the center position of the weld includes:

[0015] The assembly is rotated one circle using the turntable of the vacuum electron beam welding equipment, and the electron beam is readjusted to the center position of the weld to find the center position of the cross-line weld.

[0016] Preferably, the process parameters of the annular welding are electron beam current 8-15mA, circular wave or triangular wave, welding distance 300-400cm, acceleration voltage 30-60kv, welding speed 800-1200mm / min, electron beam scanning frequency 100-300HZ, and electron beam scanning amplitude 2-5mA.

[0017] Preferably, before the two hemispherical shell-shaped components with lock bottoms are butt-jointed and assembled, the method further comprises:

[0018] The two hemispherical shell-shaped components are subjected to surface treatment.

[0019] Preferably, performing surface treatment on the two hemispherical shell-shaped components comprises:

[0020] Cleaning the two hemispherical shell-shaped components;

[0021] The scale is scraped off by hand and then dried.

[0022] Preferably, the cleaning step comprises:

[0023] Wipe the two hemispherical shell-shaped components with an organic solvent to remove the oil stains on the surface. The manual scraping of the oxide scale includes:

[0024] Preferably, use a copper wire brush or stainless steel wire with a diameter of 0.15 mm - 0.2 mm for grinding until the metallic luster is exposed.

[0025] The beneficial effects of the present invention are as follows:

[0026] Use an elastic adjustable fastening tooling to fasten the two hemispherical shell-shaped components on both sides, ensure the uniform gap between the two hemispherical shell-shaped components, thereby reducing the welding deformation of the two thin-walled shells and ensuring the weld quality. By adjusting the electron beam welding process parameters through this method, the nail tip pores in the electron beam weld can be avoided.

[0027] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 Shows the assembly schematic diagram of the thin-walled shell aluminum alloy gas cylinder and the elastic adjustable fastening tooling of an embodiment of the present invention;

[0030] Figure 2 Shows the surface schematic diagram of the weld of the thin-walled shell aluminum alloy gas cylinder of an embodiment of the present invention.

[0031] Description of the reference numerals in the drawings:

[0032] 1 C-shaped clamping member, 2 elastic member. Specific Embodiments

[0033] The following will describe in detail the specific embodiments of the present invention with reference to the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0034] Please refer to Figure 1 and Figure 2 , this embodiment discloses an electron beam circular welding method for a thin-walled shell aluminum alloy gas cylinder, including steps such as cleaning, manually scraping the oxide scale, drying, assembling, circumferential sealing welding, adjusting the center position, circular welding, and cooling and taking out the cylinder.

[0035] The specific steps are as follows:

[0036] S1: Cleaning: Clean the two hemispherical shell components. Specifically, organic solvents can be used to wipe the two hemispherical shell components to remove surface oil stains. The organic solvents can be acetone, gasoline, etc.

[0037] S2: Manually scrape off the oxide scale: Use a copper wire brush or stainless steel wire with a diameter of 0.15 mm - 0.2 mm to polish until a metallic luster appears, preventing the oxide scale on the surface of the hemispherical shell component from affecting the welding quality.

[0038] S3: Drying: Specifically, natural air drying or low-temperature drying can be carried out for drying.

[0039] S4: Assembly: Use an elastic adjustable fastening tooling to butt-join and assemble the two hemispherical shell components with a locked bottom to obtain an assembly. The elastic adjustable fastening tooling can enable the two hemispherical shell components to achieve efficient and reliable connection, keep the gap between the two hemispherical shell components consistent, thereby reducing the welding deformation of the two thin-walled shells and ensuring the weld quality. Specifically, the elastic adjustable fastening tooling includes two oppositely arranged U-shaped clamping members 1 and an elastic member 2 arranged between the two U-shaped clamping members 1. When in use, the two hemispherical shell components can be butted through the two U-shaped clamping members 1 against the docking ears on the sides of the two hemispherical shell components, and the elastic member 2 provides a clamping force for the two U-shaped clamping members 1, thereby fastening the two hemispherical shell components. Further, the elastic member 2 can be a spring.

[0040] S5: Peripheral seal welding: Place the assembly in a vacuum electron beam welding equipment and perform peripheral seal welding. The vacuum electron beam welding equipment evacuates to 3×10 -4 mbar. The welding process parameters for peripheral seal welding are an electron beam current of 3 - 5 mA, using a circular wave or a triangular wave, an accelerating voltage of 30 - 60 kv, a welding speed of 800 - 1200 mm / min, an electron beam scanning frequency of 100 - 300 HZ, and an electron beam scanning amplitude value of 2 - 5 mA.

[0041] S6: Adjust the center position: Readjust the electron beam position to the center position of the weld. Specifically, use the turntable of the vacuum electron beam welding equipment to rotate the assembly one week, readjust the electron beam to the center position of the weld, and find back the center position of the crosshair weld. Since the material is thin-walled, during peripheral seal welding, the thin-walled shell material is prone to thermal expansion. Therefore, it is necessary to readjust the electron beam to the center position of the weld to ensure the accuracy of subsequent welding.

[0042] S7: Perform circular welding on the sealed assembly. The process parameters for circular welding are an electron beam current of 8 - 15 mA, using a circular wave or a triangular wave, a welding distance of 300 - 400 cm, an accelerating voltage of 30 - 60 kv, a welding speed of 800 - 1200 mm / min, an electron beam scanning frequency of 100 - 300 HZ, and an electron beam scanning amplitude value of 2 - 5 mA.

[0043] S8: Cooling and taking out the bottle: The assembly after the annular welding is vacuum cooled in a vacuum chamber. After cooling, the hatch is opened and taken out to obtain a thin-walled aluminum alloy gas cylinder.

[0044] The invention adopts the welding process of circumferential sealing welding and annular welding, which improves the stability of welding quality and welding efficiency, and adjusts the welding parameters of circumferential sealing welding and annular welding, thereby avoiding the generation of nail tip pores in the electron beam weld.

[0045] Visual inspection of thin-walled aluminum alloy gas cylinders shows that the surface of the welding position of the thin-walled aluminum alloy gas cylinder is bright, the weld shape is uniform, the transition between the welds and the welds and the shell is smooth, and the weld surface quality requirements are met (such as Figure 2 As shown); using non-destructive testing methods, the thin-walled shell aluminum alloy welds were subjected to radiographic testing and penetration testing. There were no defects such as pores, undercuts, cracks, weld bumps, burn-throughs, etc. on the weld surface, and the weld quality met the requirements of GJB178A-2005I level.

[0046] In summary, the present invention adopts the welding process of circumferential sealing welding and annular welding, which improves the stability of welding quality and welding efficiency, adjusts the welding parameters of circumferential sealing welding and annular welding, thereby avoiding the generation of nail tip pores in electron beam welds.

[0047] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0048] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An electron beam annular welding method for thin-walled aluminum alloy gas cylinders, characterized in that: The following steps are involved: Using an elastically adjustable fastening tool, two hemispherical shell-shaped parts are butt-jointed and assembled with a lock bottom to obtain an assembly; Placing the assembly in a vacuum electron beam welding device and performing circumferential sealing welding; Re-adjusting the electron beam position to the center of the weld, and performing annular welding on the sealed assembly; The annularly welded assembly is vacuum cooled in the vacuum chamber, and after cooling, the hatch is opened and taken out to obtain the thin-walled aluminum alloy gas cylinder.

2. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 1 is characterized in that: The elastically adjustable fastening tool comprises two relatively arranged U-shaped clamping parts and an elastic part arranged between the two U-shaped clamping parts.

3. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 2 is characterized in that: The vacuum degree in the vacuum electron beam welding equipment is 3×10 -4 mbar.

4. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 3 is characterized in that: The welding process parameters of the circumferential sealing welding are: electron beam current 3-5mA, circular wave or triangular wave, acceleration voltage 30-60kv, welding speed 800-1200mm / min, electron beam scanning frequency 100-300HZ, and electron beam scanning amplitude value 2-5mA.

5. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 4 is characterized in that: Repositioning the electron beam to the center of the weld includes: The assembly is rotated one circle using the turntable of the vacuum electron beam welding equipment, and the electron beam is readjusted to the center position of the weld to find the center position of the cross-line weld.

6. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 5, characterized in that: The process parameters of the annular welding are: electron beam current 8-15mA, circular wave or triangular wave, welding distance 300-400cm, acceleration voltage 30-60kv, welding speed 800-1200mm / min, electron beam scanning frequency 100-300HZ, and electron beam scanning amplitude 2-5mA.

7. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to any one of claims 1 to 6, characterized in that: Before assembling the two hemispherical shell-shaped parts with the lock bottom, the following is also included: The two hemispherical shell-shaped components are subjected to surface treatment.

8. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 7, characterized in that: The surface treatment of the two hemispherical shell-shaped components comprises: Cleaning the two hemispherical shell-shaped components; The scale is scraped off by hand and then dried.

9. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 8, characterized in that: The cleaning step comprises: The two hemispherical shell-shaped components are wiped with an organic solvent to remove surface oil stains.

10. The electron beam annular welding method for thin-walled aluminum alloy gas cylinders according to claim 9, characterized in that: The manual scraping of oxide scale comprises: Use a copper wire brush or stainless steel wire with a diameter of 0.15mm-0.2mm to polish until the metallic luster is exposed.

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