Incremental forming heterogeneous material thin-wall part and connection interface strengthening method thereof

Abstract

The invention relates to an incremental forming heterogeneous material thin-wall part and a connection interface strengthening method thereof.The method comprises the following steps that S1, a rotating hemispherical tool head is adopted to move along a set track, a corrugated structure is machined on the surface of an upper-layer plate, and grain fragmentation is formed on the surface of the upper-layer plate; s2, a solder resist layer is arranged on the upper surface of the lower auxiliary plate, and additive manufacturing powder is laid on the solder resist layer; s3, the corrugated surface is downwards placed on the additive manufacturing powder, so that the corrugated surface and the lower auxiliary plate jointly form a sandwich structure; s4, a rotating flat-bottom tool head is adopted for conducting stirring friction machining on the upper surface of the upper-layer plate, an additive manufacturing sintering curing structure is formed and connected with the corrugated face of the upper-layer plate, and meanwhile the sandwich structure is subjected to plastic deformation through axial feeding of the flat-bottom tool head; and S5, the heterogeneous material thin-wall part is obtained. Compared with the prior art, the method has the advantages that the interface bonding strength is improved, the load transmission efficiency and the cooperative deformation capacity are improved, high flexibility is achieved, and a high-quality interface is obtained.

Description

Technical Field

[0001] This invention relates to the field of interface strengthening technology for thin-walled heterogeneous materials, and in particular to a progressively formed thin-walled heterogeneous material and a method for strengthening the interface of its connection. Background Technology

[0002] New-generation multi-metal composite structures possess excellent properties such as lightweight, high strength, high toughness, and corrosion resistance, not only meeting the stringent requirements of modern industrial development but also demonstrating significant advantages in structural lightweighting and functionalization in transportation, aerospace, defense, and advanced equipment manufacturing. However, due to the significant differences in thermophysical properties between different metals, achieving high-quality bonding and forming between dissimilar metals remains a major challenge. To better meet the bonding quality requirements of thin-walled dissimilar materials, Kannan et al. pioneered a powder blowing directional energy deposition method to fabricate thin-walled dissimilar iron-aluminum materials. While this method can achieve the forming of thin-walled iron-aluminum dissimilar materials, the formation of a thick intermetallic compound at the iron-aluminum interface results in low interfacial bonding strength. To avoid the harmful effects of an excessively thick intermetallic compound layer, Zhang et al. used a friction stir additive manufacturing method to prepare a highly stable nanoscale amorphous structure at the iron-aluminum interface, improving the bonding strength of the iron-aluminum interface. However, these methods are still in the early stages of research and cannot yet be scaled up for the industrial production of critical thin-walled dissimilar materials. Moreover, due to the inherent characteristics of additive manufacturing, the strength and plasticity of the formed parts are somewhat inferior to those of thin-walled parts formed by rolling, and there are few cases of forming thin-walled parts of heterogeneous materials.

[0003] CN201310641847.3 discloses a sheet metal dual-point progressive forming device and forming method. The forming device includes: a pair of pressure heads disposed on both sides of the sheet metal; a pair of forming units respectively connected to the pressure heads; a pair of motion drive units respectively connected to the forming units, driving the forming units to perform orthogonal three-axis motion; a motion control system connected to the pair of motion drive units, controlling the motion drive units to move; a forming unit pressure adjustment system respectively connected to the forming units, controlling the pressure applied by the forming units to the pressure heads, so that the pressure heads are in different functional states: when the pressure heads are completely fixed, the pressure heads become forming pressure heads; when the pressure heads are flexibly pressed, the pressure heads become supporting pressure heads; and a sheet metal clamping assembly system for fixing the sheet metal and realizing the rotation of the sheet metal in the vertical and horizontal directions. However, the constraint method passively adapts to the deformation of the sheet metal and cannot actively guide the forming of curved surfaces, and cannot adapt to the forming requirements of complex curved surface contours. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a progressively formed thin-walled heterogeneous material part and a method for strengthening the interface of the part. The method features macroscopic mechanical interlocking to improve the interface bonding strength; microscopic grain gradient and fragmentation to enhance the physical and chemical bonding; improved load transfer efficiency and synergistic deformation capability; strong process controllability and high flexibility; and effective suppression of harmful phases to obtain a high-quality interface.

[0005] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for strengthening the interface of progressively formed heterogeneous thin-walled parts, comprising the following steps: S1: Fix the upper plate on the progressive forming fixture, use a rotating hemispherical tool head to move along the set trajectory, process the corrugated structure on the surface of the upper plate, and make the upper plate form a grain gradient along the thickness direction, and form grain fragmentation on the surface. S2: A solder resist layer is provided on the upper surface of the lower auxiliary plate, and additive manufacturing powder is laid on the solder resist layer; S3: Flip the upper plate with the corrugated structure so that the corrugated side is facing down and place it on the additive manufacturing powder, thereby forming a sandwich structure together with the lower auxiliary plate. S4: Fix the sandwich structure onto the progressive forming fixture, and use a rotating flat-bottomed tool head to perform stirring friction processing on the upper surface of the upper plate. The rotation of the flat-bottomed tool head generates dynamic local heating, which causes the additive manufacturing powder to sinter and solidify, forming an additive manufacturing sintered and solidified structure, which is connected to the corrugated surface of the upper plate. At the same time, the axial feed of the flat-bottomed tool head causes the sandwich structure to undergo plastic deformation. S5: After processing, remove the lower auxiliary plate to obtain a thin-walled heterogeneous material part with a grain gradient corrugated interface.

[0006] Furthermore, in S4, the sandwich structure is fixed to the progressive forming fixture and secured by a clamping device.

[0007] Furthermore, the shape of the corrugated structure on the surface of the upper plate is controlled by the size of the hemispherical tool head and the horizontal spacing in the motion trajectory; the thickness-oriented grain gradient of the upper plate is controlled by the rotational speed and axial machining passes of the hemispherical tool head.

[0008] Furthermore, in S1, when processing the corrugated structure, a pad is provided on the lower side of the upper plate to prevent the plate from concave and deforming.

[0009] Furthermore, the motion trajectory of the hemispherical tool head is a planar motion trajectory, and the axial feed is less than or equal to 0.1 mm.

[0010] Furthermore, the upper plate is made of a high-strength or high-hardness sheet material, such as high-strength steel plate.

[0011] Furthermore, the lower auxiliary plate is made of a sheet material with lower strength than the upper plate. For example, an aluminum plate.

[0012] Furthermore, in S4, before machining with a flat-bottomed tool head, a high-temperature lubricating oil is coated on the upper surface of the upper plate.

[0013] Furthermore, the movement trajectory of the flat-bottomed tool head is designed to ensure complete coverage of the processing area of ​​the upper plate within each processing height layer.

[0014] The present invention also provides a heterogeneous material thin-walled part, which is prepared by the above-mentioned progressive forming heterogeneous material thin-walled part connection interface strengthening method, wherein the heterogeneous material interface has a macroscopic corrugated interlocking structure and a microscopic grain gradient structure.

[0015] Compared with the prior art, the present invention has the following advantages: (1) Macroscopic mechanical interlocking enhances interfacial bonding strength. A macroscopic corrugated interlocking structure is created at the interface of heterogeneous materials. When the corrugated surface of the upper plate is pressed into and connected to the additively manufactured powder sintered body, this undulating structure forms a highly efficient mechanical interlocking effect. This increases the effective connection area between heterogeneous materials, thereby overcoming the problem of weak bonding force caused by differences in material physical properties and improving the interfacial bonding strength.

[0016] (2) Microscopic grain gradient and fragmentation enhance physical and chemical bonding. Based on the macroscopic corrugated structure, this invention induces grain gradient and grain fragmentation on the surface of the upper plate through a progressive forming process. This microstructure has the following effects: First, the refined grains themselves can improve the mechanical properties of the material surface; second, the large number of grain boundaries generated provide high-speed channels for element diffusion between heterogeneous materials, which greatly promotes the physical (diffusion) bonding and chemical (metallurgical) bonding effect at the interface, making the interface bonding more robust and stable.

[0017] (3) Improved load transfer efficiency and synergistic deformation capability. Due to the higher roughness and stronger mechanical interlocking of the corrugated interface, stress can be transferred more effectively between different materials when the thin-walled part of the heterogeneous material is subjected to external load. This avoids the sharp concentration of stress at the interface, so that the prepared thin-walled part of the heterogeneous material has better synergistic deformation capability, effectively reducing the risk of interface peeling or cracking during the forming or use of the component, and improving the reliability and life of the product.

[0018] (4) The process is highly controllable and flexible. The key interface features of this invention (such as corrugation shape and grain gradient) can be flexibly and precisely controlled through process parameters. The corrugation shape can be adjusted by the tool head size and the distance between the motion paths, and the grain gradient can be controlled by the tool head speed and the number of processing passes. This high degree of flexibility enables the technology to adapt to different material combinations and diverse performance requirements.

[0019] (5) Effectively suppressing harmful phases and obtaining high-quality interfaces. Unlike some fusion welding techniques that easily produce thick and brittle intermetallic compound layers (such as iron-aluminum interfaces), this invention mainly relies on the solid-state thermo-mechanical effect generated by stirring friction to achieve the connection. This relatively low heat input and strong plastic deformation help suppress the excessive growth of brittle intermetallic compounds and make it easier to obtain high-performance interface microstructures such as nanoscale amorphous materials, thereby ensuring the quality of interface connection. Attached Figure Description

[0020] Figure 1 A schematic diagram illustrating the process for strengthening the interface of a progressively formed thin-walled heterogeneous material component; Figure 2 A schematic diagram of a sandwich structure for thin-walled components made of heterogeneous materials; Figure 3 This is a schematic diagram of the friction stir progressive forming process. Figure 4 A schematic diagram of a heterogeneous thin-walled part obtained by a progressive forming heterogeneous thin-walled part interface strengthening method.

[0021] Reference numerals: 1. Flat-bottomed tool head, 2. Upper plate, 3. Additive manufacturing powder, 4. Lower auxiliary plate, 5. Clamping device, 6. Solder resist layer, 7. Additive manufacturing sintered and cured structure, 8. Hemispherical tool head, 9. Spacer block. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0023] Example 1 This embodiment provides a method for strengthening the interface of progressively formed heterogeneous thin-walled parts, such as... Figure 1-4 As shown, it includes the following steps: S1: Fix the upper plate 2 on the progressive forming fixture, and use the rotating hemispherical tool head 8 to move along the set trajectory to process the corrugated structure on the surface of the upper plate 2, and make the upper plate 2 form a grain gradient along the thickness direction, and the surface form grain fragmentation. S2: A solder resist layer 6 is provided on the upper surface of the lower auxiliary plate 4, and additive manufacturing powder 3 is laid on the solder resist layer 6; S3: Flip the upper plate 2 with the corrugated structure so that the corrugated side is facing down and placed on the additive manufacturing powder 3, thereby forming a sandwich structure together with the lower auxiliary plate 4. S4: Fix the sandwich structure onto the progressive forming fixture, and use a rotating flat-bottomed tool head 1 to perform stirring friction processing on the upper surface of the upper plate 2. The rotation of the flat-bottomed tool head 1 generates dynamic local heating, which causes the additive manufacturing powder 3 to sinter and solidify, forming an additive manufacturing sintered and solidified structure 7, which is connected to the corrugated surface of the upper plate 2. At the same time, the axial feed of the flat-bottomed tool head 1 causes the sandwich structure to undergo plastic deformation. S5: After processing, remove the lower auxiliary plate 4 to obtain a thin-walled heterogeneous material part with a grain gradient corrugated interface.

[0024] In a specific embodiment, in step S4, the sandwich structure is fixed to the progressive forming fixture and secured by the clamping device 5.

[0025] In a specific embodiment, the shape of the corrugated structure on the surface of the upper plate 2 is controlled by the size of the hemispherical tool head 8 and the horizontal spacing in the movement trajectory; the thickness-oriented grain gradient of the upper plate 2 is controlled by the rotational speed and axial machining passes of the hemispherical tool head 8.

[0026] In a specific embodiment, during the processing of the corrugated structure in S1, a pad 9 is provided on the lower side of the upper plate 2 to prevent the plate from concave and deforming.

[0027] In a specific implementation, the motion trajectory of the hemispherical tool head 8 is a planar motion trajectory, and the axial feed is less than or equal to 0.1 mm.

[0028] In a specific embodiment, the upper plate 2 is a high-strength or high-hardness plate material.

[0029] In a specific embodiment, the lower auxiliary plate 4 is a plate material with lower strength than the upper plate 2.

[0030] In a specific implementation, in step S4, before processing with the flat-bottomed tool head 1, high-temperature lubricating oil is coated on the upper surface of the upper plate 2.

[0031] In a specific implementation, the movement trajectory of the flat-bottomed tool head 1 is designed to ensure that the processing area of ​​the upper plate 2 is completely covered within each processing height layer.

[0032] This embodiment also provides a heterogeneous material thin-walled part, which is prepared by the above-described progressive forming heterogeneous material thin-walled part connection interface strengthening method. The heterogeneous material interface has a macroscopic corrugated interlocking structure and a microscopic grain gradient structure.

[0033] Example 2 This embodiment provides a method for strengthening the interface of progressively formed heterogeneous thin-walled parts, such as... Figure 1-4 As shown, it includes the following steps: S1: Fix the upper plate 2 on the progressive forming fixture, and use the rotating hemispherical tool head 8 to move along the set trajectory to process the corrugated structure on the surface of the upper plate 2, and make the upper plate 2 form a grain gradient along the thickness direction, and the surface form grain fragmentation. S2: A solder resist layer 6 is provided on the upper surface of the lower auxiliary plate 4, and additive manufacturing powder 3 is laid on the solder resist layer 6; S3: Flip the upper plate 2 with the corrugated structure so that the corrugated side is facing down and placed on the additive manufacturing powder 3, thereby forming a sandwich structure together with the lower auxiliary plate 4. S4: Fix the sandwich structure onto the progressive forming fixture, and use a rotating flat-bottomed tool head 1 to perform stirring friction processing on the upper surface of the upper plate 2. The rotation of the flat-bottomed tool head 1 generates dynamic local heating, which causes the additive manufacturing powder 3 to sinter and solidify, forming an additive manufacturing sintered and solidified structure 7, which is connected to the corrugated surface of the upper plate 2. At the same time, the axial feed of the flat-bottomed tool head 1 causes the sandwich structure to undergo plastic deformation. S5: After processing, remove the lower auxiliary plate 4 to obtain a thin-walled heterogeneous material part with a grain gradient corrugated interface.

[0034] In a specific embodiment, in step S4, the sandwich structure is fixed to the progressive forming fixture and secured by the clamping device 5.

[0035] In a specific embodiment, the shape of the corrugated structure on the surface of the upper plate 2 is controlled by the size of the hemispherical tool head 8 and the horizontal spacing in the movement trajectory; the thickness-oriented grain gradient of the upper plate 2 is controlled by the rotational speed and axial machining passes of the hemispherical tool head 8.

[0036] In a specific embodiment, during the processing of the corrugated structure in S1, a pad 9 is provided on the lower side of the upper plate 2 to prevent the plate from concave and deforming.

[0037] In a specific embodiment, the motion trajectory of the hemispherical tool head 8 is a planar motion trajectory, with a trajectory spacing of 2mm in the plane, an axial trajectory spacing of 0.1mm, and an axial motion distance of 0.3mm.

[0038] In a specific embodiment, the upper plate 2 is a high-strength steel plate.

[0039] In a specific embodiment, the lower auxiliary plate 4 is an aluminum plate.

[0040] In a specific implementation, in step S4, before processing with the flat-bottomed tool head 1, high-temperature lubricating oil is coated on the upper surface of the upper plate 2.

[0041] In a specific embodiment, the movement trajectory of the flat-bottomed tool head 1 is designed to ensure complete coverage of the processing area of ​​the upper plate 2 within each processing height layer. The in-plane trajectory spacing of the flat-bottomed tool head 1 is 2 mm, and the axial trajectory spacing is 0.5 mm.

[0042] This embodiment also provides a heterogeneous material thin-walled part, which is prepared by the above-described progressive forming heterogeneous material thin-walled part connection interface strengthening method. The heterogeneous material interface has a macroscopic corrugated interlocking structure and a microscopic grain gradient structure.

[0043] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0044] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method of strengthening the interface of a connection of a thin-walled component of heterogeneous material by incremental forming, characterized in that The method comprises the following steps: S1: fixing the upper plate (2) on a progressive forming tool, using a rotating hemispherical tool head (8) to move along a set trajectory to process a corrugated structure on the surface of the upper plate (2) and form a grain gradient in the thickness direction of the upper plate (2) and grain fragmentation on the surface; S2: setting a solder resist layer (6) on the upper surface of the lower auxiliary plate (4) and laying additive manufacturing powder (3) on the solder resist layer (6); S3: turning over the upper plate (2) processed with the corrugated structure and placing it with the corrugated surface downward on the additive manufacturing powder (3) to form a sandwich structure together with the lower auxiliary plate (4); S4: fixing the sandwich structure on a progressive forming tool, using a rotating flat-bottom tool head (1) to perform friction stir processing on the upper surface of the upper plate (2), the rotation of the flat-bottom tool head (1) generates dynamic local heating, the additive manufacturing powder (3) is sintered and solidified to form an additive manufacturing sintered and solidified structure (7) connected with the corrugated surface of the upper plate (2), and the sandwich structure is plastically deformed through the axial feeding of the flat-bottom tool head (1); S5: after processing, removing the lower auxiliary plate (4) to obtain a heterogeneous material thin-walled part with a grain gradient corrugated interface.

2. The method of claim 1, wherein the method is characterized by: In S4, the sandwich structure is fixed on the progressive forming tool through a clamping device (5).

3. The method of claim 1, wherein the method further comprises: The shape of the corrugated structure on the surface of the upper plate (2) is controlled by the size of the hemispherical tool head (8) and the horizontal spacing in the movement trajectory; the thickness grain gradient of the upper plate (2) is controlled by the rotational speed of the hemispherical tool head (8) and the axial processing pass.

4. The method of claim 1, wherein the method further comprises: In S1, a pad (9) is arranged on the lower side of the upper plate (2) to prevent the plate from being deformed downward.

5. The method of claim 1, wherein the method further comprises: The movement trajectory of the hemispherical tool head (8) is a planar movement trajectory, and the axial feeding amount is less than or equal to 0.1 mm.

6. The method of claim 1, wherein the method is characterized by: The upper plate (2) is a high-strength or high-hardness plate.

7. The method of claim 1, wherein the method further comprises: The lower auxiliary plate (4) is a plate with lower strength than the upper plate (2).

8. The method of claim 1, wherein the method is characterized by: In S4, before processing with the flat-bottom tool head (1), high-temperature lubricating oil is applied to the upper surface of the upper plate (2).

9. The method of claim 1, wherein the method further comprises, The movement trajectory of the flat-bottom tool head (1) is designed to ensure that the to-be-processed area of the upper plate (2) can be completely covered in each processing height layer.

10. A thin-walled heterogeneous material part, characterized in that, The progressive forming heterogeneous material thin-walled part connection interface strengthening method is prepared by any one of claims 1-9, and the heterogeneous material interface has a macro corrugated interlocking structure and a micro grain gradient structure.

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