Micro-zone repair welding method for aluminum alloy defect

Abstract

The repairing welding for aluminum alloy defects starts with deciding defect location, trimming before the welding, degreasing for the repairing area, micro zone weld repairing using pulse energy, inspecting the working piece to make sure the repairing quality, till the nonexistence of leakage of the part. It also relates to the pulse energy micro bonding machine. Without affecting the dimension of the base metal, it can repair the defect, meeting the sealing requirement.

Description

technical field [0001] The invention relates to a micro-area repair welding method capable of performing airtight repair on aluminum alloy base material and aluminum alloy brazing seam defects, and belongs to the technical field of welding methods in forming technology. Background technique [0002] The miniaturization and light weight of radar make the application of aluminum alloy very extensive. Many high-precision and complex workpieces are made of aluminum alloy. Due to the complicated weld seam and high size requirements of the workpiece, only brazing process can be used for sealing connection. However, due to the complex shape of the workpiece and the long brazing seam, there is no 100% guarantee that the brazing seam will not leak; at the same time, although the weld seam has good compactness after welding, due to the unavoidable follow-up process that destroys the weld seam, Such as conductive oxidation, machining, etc. may cause leakage of the original airtight wor...

AI Technical Summary

Problems solved by technology

However, due to the complex shape of the workpiece and the long brazing seam, there is no 100% guarantee that the brazing seam will not leak; at the same time, although the weld seam has good compactness after welding, due to the unavoidable follow-up process that destroys the weld seam, Such as conductive oxidation, machining, etc. may cause leakage of the original airtight workpiece

If secondary brazing is used to repair the weld, the quality of the weld is difficult to be guaranteed, the success rate of welding defects in the local brazing seam is low, and the size of some problematic workpieces is already in place, so it is impossible to perform secondary brazing to repair leaks; the process of repairing glue is used Measures to ensure the airtightness of components have hidden dangers in the quality and reliability of weather resistance and durability. Therefore, it is necessary to study a welding repair process with convenient operation and good accessibility to meet the requirements of sealing performance and improve product quality.

[0003] The low energy density welding methods in the prior art, such as argon tungsten arc welding, have low arc energy density and slow heating speed. When used for brazing seam repair welding, not only the base metal in the welding repair area will be melted, but also the welding repair area will be re-melted There is a risk of introducing new joint defects

For the same reason, when argon tungsten arc welding is welding a workpiece whose wall thickness is less than 1mm, it is difficult to control the size of the weld pool, and it is easy to burn down and burn through the workpiece; In a better area, a large welding current and a long heating time must be used to melt the workpiece; moreover, this method has a large deformation after welding, and the dimensional accuracy of the workpiece will be affected after welding repair. It can be seen that the tungsten plate argon Arc welding cannot meet the requirements of weld repair for local micro-area of ​​brazing seam defects

[0004] The variable polarity plasma welding in the prior art is an improved form of argon tungsten arc welding. It is a compressed arc, and its energy density is much higher than that of a free arc of argon tungsten arc. Deep, small heat-affected zone, but when used for brazing repair, there are still problems such as re-melting the brazing seam outside the welding repair area, and the molten pool is difficult to control.

[0005] In the MIGA welding in the prior art, the arc is generated between the welding wire and the workpiece, and the physical and chemical properties of the aluminum alloy are unique, and the thermal conductivity, specific heat, and melting potential are very large, such as the thermal conductivity is 225.3 W / M.K is more than twice as large as steel. During welding, a large amount of arc energy is quickly transmitted to the inside of the base metal and lost, which is easy to form defects such as lack of fusion, especially when the base metal at the arc ignition is in a cold state. Defects such as pores and brazing seams are generally relatively small, and they are just in the arc starting section when using gas shielded welding. Therefore, gas shielded welding is not suitable for welding defects in brazing seams.

[0006] Both laser welding and electron beam welding in the prior art belong to high-energy beam welding, but the aluminum alloy has a low absorption rate of laser light, and high power is required for welding aluminum alloy, and the high-power laser welding torch has a large volume due to water cooling and other reasons , the accessibility and flexibility of the operation are not good, and the brazing seam defects may occur in any part of the workpiece, so laser welding can only solve part of the brazing defects, and there is nothing that can be done for the embarrassing parts

Electron beam welding is carried out in a vacuum chamber, and its visibility, accessibility and flexibility are worse than laser welding, and it is not suitable for welding repair of aluminum brazing seams

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