Method for Controlling Surface Groove Defects of Three-Layer Hollow Sandwich Structure

Abstract

The invention relates to a method for controlling surface groove defects of a three-layer hollow sandwich structure in the field of welding technology. The method includes: performing high-energy beam modification treatment on both sides of the diffusion connection part of the upper panel and the lower panel of the titanium alloy, obtaining a gradient structure with high temperature deformation resistance, and suppressing local deformation around the connection part during superplastic forming; The surfaces of the upper panel, the lower panel and the core plate of the gradient tissue are all cleaned; an upper cover and a lower cover suitable for the size of the upper panel and the lower panel are prepared, and the upper cover and the lower cover are The deformation resistance of the titanium alloy panel is higher than that of the plastic deformation resistance of the titanium alloy panel; the lower sheath, the lower panel, the core board, the upper panel and the upper sheath are coated with solder stopper and then stacked from bottom to top, and the laminated structure is surrounded. The seal is welded and sealed, and vent holes are reserved; the upper and lower sheaths are removed after the laminated sealed structure is heated and pressurized to realize diffusion connection and superplastic forming.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a method for controlling surface groove defects of a three-layer hollow sandwich structure. Background technique [0002] Superplastic forming / diffusion joining technology has the advantages of near-net shape, good integrity, high rigidity, and large design freedom in the manufacture of hollow structural parts, and is widely used in aviation, aerospace and other fields. According to the number of layers required for the manufacture of the structure, the process structure can be divided into single-layer, two-layer, three-layer and four-layer structures. One of the difficulties in forming the three-layer structure is that surface groove defects are difficult to control. Generally, through Increase the skin thickness to reduce groove defects, therefore, its structural weight increases, limiting its scope of use and structural design margin. In addition to increasing the thickness...

AI Technical Summary

Problems solved by technology

According to the number of layers required for the manufacture of the structure, the process structure can be divided into single-layer, two-layer, three-layer and four-layer structures. One of the difficulties in forming the three-layer structure is that surface groove defects are difficult to control. Generally, through Increase skin thickness to reduce groove defects, therefore, its structural weight increases, limiting its scope of use and structural design margin

In addition to increasing the thickness of the skin to reduce the groove, the groove can also be covered by the outer skin by increasing the number of skin layers. However, the performance of the parts formed by this method is difficult to meet the design requirements

[0003] For the three-layer structure (including the middle core board and the skin panels on both sides), based on engineering experience, usually the thickness of the skin is more than 3 times the thickness of the middle core board to obtain parts without groove defects on the surface, and with the height of the cavity The increase of the skin thickness increases, and then through the surface thinning treatment, the excess thickness of the skin is removed to meet the design requirements. This method is a serious waste of materials, especially for parts with a high cavity height, and the process is complicated and complicated.

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