Electron beam welding method for ZL114A cast aluminum alloy fuel tank products

Abstract

The invention provides an electron beam welding method for a ZL114A cast aluminum alloy oil tank product. The method comprises a pre-welding preparation step and a welding step. Wherein the welding part comprises the steps of spot fixed position welding and sealing welding of formal welding. According to the electron beam welding method provided by the invention, the defects of air holes, inclusions and the like in electron beam welding of ZL114A cast aluminum alloy fuel tank products are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of high-energy beam welding, and specifically relates to an electron beam welding method for oil tank products with a lock bottom structure made of ZL114A cast aluminum alloy, which solves the defects of pores, inclusions, etc. in ZL114A metal electron beam welding. Background Art

[0002] ZL114A aluminum alloy is a high-strength cast aluminum alloy of Al-Si-Mg series, which has both high mechanical properties and excellent casting process performance and welding performance. In the field of aerospace, this alloy can be used to manufacture complex thin-walled structural parts with large load-bearing capacity, especially shell and fuel tank parts. Most fuel tanks are formed by two or more compartments through electron beam welding, which places high demands on welding quality.

[0003] As a high-energy-density precision welding method performed in a vacuum environment, electron beam welding has many advantages, such as high welding power density, large aspect ratio, small deformation of the welding area, low energy consumption, and easy control and automation. At present, electron beam welding has been widely used in the fields of aerospace, weapons and equipment manufacturing, and the electronics industry. Although compared with conventional fusion welding methods, electron beam welding technology can greatly improve the tensile strength of welded joints, reduce residual deformation, and improve the quality of welded joints, for the welding of ZL114A cast aluminum alloy materials, due to the active chemical properties of cast aluminum alloys, defects such as pores and inclusions are easily generated during electron beam welding, which is still the biggest obstacle to its application.

[0004] In addition, with the improvement of product research and development efficiency, the welding technology level is required to be continuously improved, and a high requirement is put forward for the first-time qualified rate of welding. Therefore, the art needs an electron beam welding method that can improve the first-time qualified rate of welding. Summary of the invention

[0005] In the ZL114A cast aluminum alloy fuel tank products, the fuel tank products are composed of two compartments, and the two compartments are respectively cast, machined, and welded by tungsten inert gas arc welding, and then the two compartments are closed and formed by electron beam welding, and finally the airtightness and oil pressure oil penetration test are carried out. The first-time pass rate of vacuum electron beam welding determines the first-time pass rate of the fuel tank. The main defects of the vacuum electron beam welding process for ZL114A cast aluminum alloy are pores and inclusions. To this end, the present invention provides an electron beam welding method for ZL114A cast aluminum alloy fuel tank products, which effectively solves the problems of welding pores and inclusions of the shell fuel tank products of ZL114A cast aluminum alloy, thereby obtaining an electron beam weld with a uniform and beautiful appearance, greatly improving the first-time pass rate of the mailbox.

[0006] Specifically, the present invention adopts the following technical solution to solve the above technical problem: an electron beam welding method for ZL114A cast aluminum alloy fuel tank products, which is divided into two parts: pre-welding preparation and welding, and specifically includes:

[0007] Preparation before welding:

[0008] Step 1: Wipe clean the oil stains on the surface of the front and rear cabins within a range of at least 20mm to be welded with alcohol.

[0009] Step 2: Use a scraper to scrape the surface of the front and rear cabins within a range of at least 20 mm until the metallic luster is revealed.

[0010] Step 3: Use tooling and callipers to assemble the front and rear cabins of the product together; preferably, the assembly gap is no more than 0.2 mm.

[0011] Step 4: Use a three-jaw chuck to place the assembled product (fuel tank) in the vacuum chamber.

[0012] The welding process is divided into two steps: spot-fixed welding and formal welding:

[0013] Step 5: Evacuate the electron beam welder to a vacuum degree of 5X10 -3 mbar.

[0014] Step 6: Raise the high voltage of the electron beam welder to the corresponding acceleration voltage, use a small beam current to find the position and focusing current corresponding to the focus of the electron beam surface, and input the obtained focusing current into the welding program.

[0015] Step 7: Move the product and move the weld seam to be welded to the focus of the electron beam.

[0016] Step 8: Spot fixed position welding: perform spot fixed position welding of selected points symmetrically in sections; preferably, the process parameters of spot fixed position welding are: voltage 50-60kv, welding current 12-16mA, focusing current 2100-2150mA, welding speed 800-1200mm / min, frequency 600-1000HZ, amplitude 0.3-0.7.

[0017] Step 9: After the spot welding is completed, vacuum cool for 10 minutes, remove the vacuum and remove the callan.

[0018] Step 10: Repeat steps 5 to 7.

[0019] Step 11: Start the welding procedure to seal the entire weld seam, complete the welding of the entire weld seam, and then perform surface modification welding to complete the welding. Preferably, the process parameters of the formal welding are: voltage 50-60kV, welding current 25-35mA, welding speed 800-1200mm / min, focusing current 2100-2150mA, frequency 600-900HZ, amplitude 0.3-0.6; preferably, the electron beam focus is not aimed at the center of the weld seam but at the rear cabin 0.1mm for the entire welding work. The process parameters of the modification welding are the same as those of the formal welding.

[0020] The advantages of the electron beam welding method for ZL114A cast aluminum alloy fuel tank products provided by the present invention are:

[0021] 1) The assembly gap between the front and rear compartments is no more than 0.2mm, thereby reducing the welding deformation of the fuel tank and ensuring the quality of the weld.

[0022] 2) Utilize the penetrating ability of the electron beam to adjust the electron beam welding process parameters to avoid the generation of pores and inclusions in the electron beam weld.

[0023] 3) The electron beam flow is biased towards the rear cabin by 0.1 mm to avoid unqualified welding joint quality due to misalignment, thereby avoiding the generation of pores and inclusions in the electron beam weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 The present invention discloses an exemplary structure of a welded joint in an electron beam welding method for a ZL114A cast aluminum alloy fuel tank product.

[0026] Figure 2 The electron beam focusing position diagram of the electron beam welding method of the ZL114A cast aluminum alloy oil tank product of the present invention.

[0027] Figure 3 The present invention provides a radiographic negative film of a product obtained by the electron beam welding method for a ZL114A cast aluminum alloy fuel tank product and a product obtained by a comparative process. DETAILED DESCRIPTION

[0028] The following is a detailed description of "an electron beam welding method for ZL114A cast aluminum alloy fuel tank products" of the present invention in conjunction with the accompanying drawings.

[0029] An electron beam welding method for ZL114A cast aluminum alloy fuel tank products, including two parts: pre-welding preparation and welding:

[0030] The preparation steps before welding are as follows:

[0031] Step 1: Wipe clean the oil stains on the surface within 20mm of the front and rear compartments of the fuel tank to be welded with alcohol.

[0032] Step 2: Use a scraper to scrape the surface within 20mm of the front and rear cabins to be welded until the metallic luster is revealed.

[0033] Step 3: Use the tooling and callipers to assemble the front and rear cabins together, with the assembly gap no greater than 0.2mm.

[0034] Step 4: Place the assembled oil tank in the vacuum chamber using a three-jaw chuck. Figure 1 The preferred example dimensions (unit: mm) for this weld joint structure, in which the penetration depth must be determined to be 4 mm, the lock bottom can generally be greater than or equal to 3 mm, and similarly, the lock bottom width can be greater than or equal to 7 mm.

[0035] The welding process steps are as follows:

[0036] Step 1: Evacuate the electron beam welder to a vacuum degree of 5X10 -3 mbar.

[0037] Step 2: Raise the high voltage of the electron beam welder to the corresponding acceleration voltage, use a small beam current to find the position and focusing current corresponding to the focus of the electron beam surface, and input the obtained focusing current into the welding program.

[0038] Step 3: Move the workpiece and move the weld seam to be welded to the focus of the electron beam.

[0039] Step 4: Spot fixed position welding. Spot fixed position welding is performed symmetrically in sections. Preferably, fixed point welding is performed in sections on the circumference. One section is selected every 30° on the circumference, with a total of 12 sections, each section is about 40 mm long. The welding process parameters are: voltage 50-60 kV, welding current 12-16 mA, focusing current 2100-2150 mA, welding speed 800-1200 mm / min, frequency 600-1000 Hz, and amplitude 0.3-0.7.

[0040] Step 5: After the spot welding is completed, vacuum cool for 10 minutes, remove the vacuum and remove the calliper.

[0041] Step 6: Repeat step 1, step 2, and step 3.

[0042] Step 7: Start the welding procedure and perform surface modification welding as appropriate after sealing welding. The welding process parameters are: voltage 50-60kV, welding current 25-35mA, welding speed 800-1200mm / min, focusing current 2100-2150mA, frequency 600-900HZ, amplitude 0.3-0.6, and the electron beam focus is 0.1mm behind the cabin for the entire welding process (see Figure 2 ).

[0043] On this basis, see Figure 3 , which provides internal quality under different process parameters and quality judgment based on radiographic inspection. Figure 3 In the middle a figure, when the whole weld is conventionally welded at a current of 25mA and a speed of 600mm / min, a defective product with a single pore is likely to appear; when the speed is too low, a single pore is likely to appear. Figure 3 In the middle b figure, when the whole weld is conventionally welded at a current of 25 mA and a welding speed of 1300 mm / min, chain-like pores are likely to appear; when the welding speed is too high, chain-like pores are likely to appear. However, the internal quality of the product obtained by the above method of the present invention is tested by radiographic inspection and there is no pore defect.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An electron beam welding method for ZL114A cast aluminum alloy fuel tank products, characterized in that: The method comprises the following steps: 1) Wipe clean the oil stains on the surface of the front and rear cabins within a range of at least 20mm to be welded with alcohol; 2) Use a scraper to scrape the surface of the front and rear cabins within a range of at least 20 mm until the metallic luster is revealed; 3) Use tooling and callipers to dock and assemble the front and rear cabins of the product; 4) placing the product assembled in step 3) in a vacuum chamber using a three-jaw chuck; 5) The electron beam welding machine is vacuumed, and the vacuum degree reaches 5X10 -3 mbar; 6) Raise the high voltage of the electron beam welder to the corresponding acceleration voltage, use a small beam current to find the position and focusing current corresponding to the focus of the electron beam surface, and input the obtained focusing current into the welding program; 7) Move the product and move the weld seam of the product to be welded to the focus of the electron beam; 8) Spot fixed position welding: perform fixed position welding of selected points symmetrically in sections; 9) After the spot welding is completed, vacuum cool for 10 minutes, remove the vacuum and remove the calliper; 10) Repeat step 5), step 6) and step 7); 11) Start the welding procedure and perform formal welding to seal the entire weld, followed by touch-up welding to complete the welding.

2. The electron beam welding method for ZL114A cast aluminum alloy fuel tank products according to claim 1 is characterized in that: In the step 3), the assembly gap between the front compartment and the rear compartment is no greater than 0.2 mm.

3. The electron beam welding method for ZL114A cast aluminum alloy fuel tank products according to claim 1 is characterized in that: In the step 8), the spot fixed position welding process parameters are: voltage 50-60kv, welding current 12-16mA, focusing current 2100-2150mA, welding speed 800-1200mm / min, frequency 600-1000HZ, amplitude 0.3-0.

7.

4. The electron beam welding method for ZL114A cast aluminum alloy fuel tank products according to claim 1 is characterized in that: In the step 11), the formal welding process parameters are: voltage 50-60 kV, welding current 25-35 mA, welding speed 800-1200 mm / min, focusing current 2100-2150 mA, frequency 600-900 Hz, amplitude 0.3-0.

6.

5. The electron beam welding method for ZL114A cast aluminum alloy fuel tank products according to claim 1 is characterized in that: In the step 11), the electron beam focus is offset from the rear cabin by 0.1 mm.

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