A method for manufacturing a corner code component

Abstract

This invention discloses a manufacturing method for corner code components, aiming to solve the problem of springback deformation caused by residual stress release during welding and assembly of corner code components. The method includes: providing a base plate and a bent support component with internal residual stress; remelting the mating end faces of the support component using a high-energy beam heat source to form a micro-surface texture containing micro-channels and wedge-shaped micro-protrusions; abutting the support component against the base plate and providing solder, heating to austenitize the matrix and locally soften the base plate; rapid cooling to induce a martensitic phase transformation, utilizing phase transformation expansion to allow high-hardness micro-protrusions to penetrate the base plate, forming mechanical anchoring, while the micro-channels contract and compress the liquid solder, building compressive stress within the matrix; subsequent heating for carbon distribution, and finally cooling to solidify the weld. This invention, through the synergy of phase transformation expansion and micro-texture, generates in-situ compressive stress to resist springback deformation, achieving high-precision, high-strength welding of corner codes without the need for external rigid clamps.

Description

Technical Field

[0001] This invention relates to the field of metal component forming and connection technology, and specifically to a method for manufacturing a corner bracket assembly. Background Technology

[0002] Corner brackets, as typical load-bearing and connecting components, occupy an important position in high-end equipment manufacturing and precision mechanical structures. In the existing manufacturing process, corner bracket components are mostly formed from metal sheets through stamping or bending processes to create support components with a certain geometric structure, and then the end faces of the support components are welded to the base plate.

[0003] However, existing manufacturing methods face two main technical challenges. First, the bending process during the forming stage of the support component causes severe lattice slippage within the material, resulting in the accumulation of high-intensity residual stress at the bending corners. When the support component is subsequently thermally connected to the base plate, the residual stress is thermally activated and released, causing uncontrollable warping and springback deformation in the macroscopic morphology of the support component. Due to this limitation, engineering applications often necessitate the use of complex external rigid clamps for forced pressure holding and positioning of the support component, leading to complex processes, high costs, and difficulty in eliminating residual deformation deviations after clamp removal. Second, limited by the machining accuracy of the stamped part's end face, the assembly gap between the supporting component's mating end face and the base plate often fails to meet ideal flatness requirements, exhibiting disordered fluctuations. This irregular assembly gap, during capillary brazing, easily leads to uneven solder penetration, porosity, and localized incomplete welds within the weld, severely restricting the fatigue strength and structural reliability of the connection interface. Summary of the Invention

[0004] This invention proposes a manufacturing method for corner bracket components, which aims to solve the problem of springback deformation caused by residual stress release in the support component, while eliminating welding defects caused by irregular assembly gaps between the support component and the base plate, and achieving high-precision assembly and high-strength metallurgical connection without the need for complex external fixture constraints.

[0005] The method for manufacturing corner code components provided by the present invention includes the following steps: S1. Provide a heat-treatable carbon-containing metal sheet, cut into a base plate and bent into a support with butt joints and residual stress in the bent part. S2. Use a high-energy beam heat source to perform surface remelting on the docking end face to form a surface texture with micro-roughness. S3. Place the support on the base plate so that the mating end face abuts against the base plate, and use the surface texture to define the assembly gap between the mating end face and the base plate. S4. Solder is provided and heated at the assembly gap, so that the solder melts into liquid solder and seeps into the assembly gap under capillary action, and the base area of ​​the support near the mating end face is heated and transformed into austenite. S5. Stop heating to cool the base region to within the martensitic phase transformation temperature range, causing some of the austenite in the base region to transform into martensite and generate volume expansion, causing the assembly gap to shrink and extruding the liquid solder inside, and generating compressive stress in the base region. S6. Before the liquid solder in the assembly gap solidifies, it is heated again to raise the temperature of the base region to and maintain it at the distribution temperature, so that the carbon element in the martensite can be distributed and diffused into the untransformed austenite to form carbon-rich austenite. S7. Stop heating and cool the base region to room temperature so that the carbon-rich austenite in the base region transforms into a high-toughness structure; and allow the liquid solder to solidify and form a weld connecting the support and the base plate; and use the compressive stress in the base region to constrain the support to resist the springback deformation of the support caused by the internal residual stress.

[0006] Preferably, in step S2, the surface texture includes micro-channels extending along the thickness direction of the mating end face, and micro-protrusions distributed on both sides of the micro-channels. In step S4, the liquid solder undergoes directional capillary penetration along the micro-channels; In step S5, when the substrate region expands in volume, the micro-protrusions are displaced toward the base plate and penetrate into the base plate; and the cross-section of the micro-channel contracts to squeeze the liquid solder inside it.

[0007] Preferably, the carbon mass fraction of the carbon-containing metal sheet is 0.18% to 0.45%.

[0008] Preferably, in steps S4 and S6, high-frequency induction heating is used as the heat source, and the heating area is limited to a local area of ​​the support member adjacent to the mating end face.

[0009] Preferably, in step S5, the martensitic transformation temperature range is between the martensitic transformation start temperature and the martensitic transformation end temperature of the carbon-containing metal plate. In step S6, the distribution temperature is higher than the martensitic transformation start temperature and lower than the bainitic transformation start temperature of the carbon-containing metal plate.

[0010] Preferably, in step S2, a laser beam or electron beam is used to continuously scan the mating end face, causing the surface metal of the mating end face to melt rapidly and solidify extremely quickly, so as to form the surface texture.

[0011] Preferably, the support member includes an integrally formed middle plate, two side plates, and two end plates; The two side plates are respectively vertically connected to opposite sides of the middle plate and are arranged symmetrically. The two end plates are respectively vertically connected to the sides of the two side plates that are perpendicular to the middle plate, and extend from the two side plates in opposite directions. There are three mating end faces in total. One of the mating end faces is located on the side of the middle plate and is used to abut against the side of the bottom plate. The other two mating end faces are located on the bottom edges of the two end plates respectively and are used to abut against the surface of the bottom plate.

[0012] Preferably, both side plates and both end plates are provided with mounting holes for external connectors to pass through.

[0013] One or more technical solutions provided in this invention have at least the following technical effects or advantages: After the initial heating causes the molten solder to penetrate the assembly gap and induce austenitization in the base region near the mating surface of the support component, controlled cooling brings the base region into the martensitic transformation temperature range. The significant volume expansion accompanying the martensitic transformation rapidly forms a strong interference fit between the constrained base region and the base plate. This expansion effect actively contracts the assembly gap, applying direct physical compression to the still molten solder inside, forcibly expelling air bubbles and impurities from the weld, fundamentally eliminating incomplete weld defects and significantly improving the interfacial density of the formed weld.

[0014] The volume expansion generated by this phase transition process creates high-density compressive stress within the matrix region. This stress, combined with the cured weld seam, firmly anchors the connecting ends of the support component to the base plate, constructing a strong rigid constraint within the macroscopic structural system. This constraint effectively counteracts and resists the springback tendency of the support component caused by the release of residual stress at bending points. It achieves a spontaneous balance between microscopic phase transition compressive stress and macroscopic residual stress, eliminating the reliance on external rigid alignment fixtures in traditional processes while maintaining the three-dimensional assembly accuracy of the components.

[0015] A second heating process is introduced before the liquid solder solidifies, and the temperature is maintained at the partitioning temperature. This drives the supersaturated carbon atoms inside the martensite to partition and diffuse into the untransformed residual austenite. The carbon-rich austenite transforms into a high-toughness structure upon final cooling to room temperature, effectively eliminating the localized brittle bands that are prone to occur in high-strength carbon steel under conventional welding thermal cycles. This allows the root of the corner bracket connection to maintain ultra-high yield strength while also possessing excellent plastic impact resistance.

[0016] Furthermore, the surface texture generated by the remelting of the mating ends optimizes the welding hydrodynamic environment. This surface texture not only defines a highly consistent assembly gap in terms of physical structure, but also significantly increases the contact wetting area of ​​the liquid solder from the perspective of surface tension. This drives the solder to achieve deep and uniform directional capillary penetration with the assistance of the micro-texture, laying a solid process foundation for subsequent phase change extrusion and high-strength bonding. Attached Figure Description

[0017] Figure 1 This is a three-dimensional exploded view of the corner bracket assembly provided in an embodiment of the present invention before welding and assembly; Figure 2 This is a three-dimensional assembly diagram of the corner bracket assembly after welding, provided in an embodiment of the present invention. Figure 3 This is a partial microscopic cross-sectional view of the mating end face of the support member provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached drawings: 10, support member; 11, mating end face; 12, middle plate; 13, side plate; 14, end plate; 15, mounting hole; 20, bottom plate; 30, micro-guide channel; 31, micro-protrusion. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Reference Figures 1 to 3 As shown, this embodiment of the invention provides a method for manufacturing corner code components. This method deeply integrates micro-surface texture design with quenching and partitioning heat treatment processes to achieve high-precision and high-strength corner code component assembly and welding without the need for external rigid fixtures. The manufacturing method specifically includes the following processes.

[0021] Combination Figure 1The corner bracket assembly shown is in a three-dimensional disassembled state before welding assembly. Step S1 involves providing a heat-treatable carbon-containing metal sheet, which is then cut into a base plate 20 and bent into a support member 10. In practice, the carbon-containing metal sheet can be made of medium-carbon structural steel such as 45 steel, high-strength low-alloy steel, or duplex steel, materials with phase transformation strengthening potential. The base plate 20 can be an independent flat plate structure or a flange or load-bearing surface of other large foundation components. During the forming process, the support member 10 undergoes cold stamping or CNC bending, inevitably generating and accumulating strong macroscopic residual stress at the inner and outer bending radii of its bent parts. The main structure of the support member 10 is designed as a multi-dimensional spatial bending form, such as... Figure 1 As shown, the support member 10 includes a central plate 12, with side plates 13 perpendicularly connected to opposite sides of the central plate 12. Each side plate 13 has an end plate 14 extending in opposite directions further perpendicularly connected to its outer side. Both the end plate 14 and the side plates 13 have pre-set mounting holes 15 for subsequent assembly. The support member 10 has three mating end faces 11, two of which are located at the bottom edges of the two end plates 14, and the third mating end face 11 is located on the side of the central plate 12.

[0022] Following step S2, a high-energy beam heat source is used to remelt the surfaces of the three mating end faces 11 to create a surface texture with microscopic roughness. The high-energy beam heat source can be a nanosecond or picosecond-level pulsed laser beam or an electron beam. By controlling the energy density and scanning trajectory of the beam, the surface metal of the mating end faces 11 undergoes localized melting and rapid solidification, thereby reconstructing its microstructure. Figure 3 The schematic diagram shows a partial microscopic cross-sectional view of the mating end face 11. This surface texture includes micro-channels 30 extending along the thickness direction of the mating end face 11, and micro-protrusions 31 distributed on both sides of the micro-channels 30. (See attached diagram.) Figure 3 As shown in the geometric profile of the micro-protrusion 31, it is preferably presented as a wedge-shaped or pyramidal structure in order to provide concentrated physical contact stress in subsequent processes.

[0023] After surface remelting is completed, proceed to step S3, where the support 10 is placed on the base plate 20, so that the three mating end faces 11 abut against the upper surface of the base plate 20 respectively. Since the mating end faces 11 have been formed with a surface texture, the tips of the wedge-shaped micro-protrusions 31 will contact the base plate 20 first. This discrete point-line contact feature naturally defines a uniform assembly gap between the mating end faces 11 and the base plate 20.

[0024] In the following step S4, solder is provided and heated at the assembly gap. The solder can be a copper-based, silver-based, or nickel-based high-temperature solder suitable for steel connections. Heating is achieved using high-frequency induction heating or a vacuum furnace. As the temperature rises, the solder melts into a liquid state and, driven by surface tension, undergoes deep and directional capillary penetration along the flow channels provided by the micro-channels 30. During this heating process, not only does the matrix region of the support 10 adjacent to the mating end face 11 cross the phase transformation critical point and transform into austenitic structure, but the local surface region of the base plate 20 in contact with the mating end face 11 also experiences significant thermal softening due to high-temperature heat conduction, resulting in a substantial decrease in the material's yield strength and an exhibiting high-temperature plastic state.

[0025] Step S5 is the key extrusion and locking stage of this invention. In this step, heating is stopped, and the matrix region is rapidly cooled to within the martensitic transformation temperature range (between the start and end temperatures) by controlling the cooling medium or environment. During this process, some austenite in the matrix region undergoes diffusionless shear transformation into martensite. The formation of martensite is accompanied not only by dramatic volume expansion but also by a sharp increase in the hardness of the micro-protrusions 31. Since the surface of the base plate 20 is still in a thermally softened state, the high-hardness micro-protrusions 31, which are undergoing volume expansion, generate significant stress concentration, forcing the local surface of the base plate 20 to undergo plastic yielding. Therefore, the micro-protrusions 31 do not push the support 10 away from the base plate 20 but instead directly penetrate and embed into the surface of the base plate 20, forming a strong micro-mechanical anchor. Simultaneously, the cross-section of the micro-channel 30 is forced to contract due to the expansion of the matrix, applying direct physical extrusion to the liquid solder retained within it. This physical extrusion process forces out tiny air bubbles and impurities from inside the weld, significantly reducing its porosity. This volumetric expansion and penetration process creates extremely high-density compressive stress within the matrix region, which forms a strong, rigid constraint through the contact interface.

[0026] To further optimize the microstructure, in step S6, a second heating is introduced before the liquid solder in the assembly gap completely solidifies, raising and maintaining the temperature of the matrix region at a specific partitioning temperature, specifically set between 250°C and 400°C. This step provides sufficient kinetic conditions for the supersaturated carbon atoms within the martensite, promoting their partitioning and diffusion into the untransformed retained austenite.

[0027] Finally, in step S7, heating is stopped and the base region is cooled to room temperature. The carbon-rich austenite, which absorbed a large number of carbon atoms during the partitioning process, acquires extremely high thermodynamic stability. Upon cooling to room temperature, it transforms into high-toughness structures such as retained austenite or lower bainite, thereby eliminating the brittleness risk at the joint root at the microscopic level and endowing this region with excellent impact resistance. Simultaneously, the liquid solder completely solidifies as the temperature decreases, forming a dense metallurgical weld, thus achieving the desired weld structure. Figure 2 The corner bracket assembly shown is the overall assembly structure after welding. At this point, the extremely high density of compressive stress built up in the matrix region adjacent to the mating end face 11 due to martensitic phase transformation expansion in step S5 is permanently locked by the thoroughly cured weld. Figure 2 In the macroscopic structural system shown, when the support member 10 is formed by cold stamping or CNC bending, a macroscopic residual stress gradient inevitably exists at the bending part, with the outer layer under tension and the inner layer under compression. Under the induction of conventional welding heat conduction, this macroscopic residual stress tends to be released rapidly, thereby generating a macroscopic springback deformation tendency that causes the bending angle of the support member 10 to expand or twist, that is, generating an outward springback bending moment on the main body of the support member 10. However, the compressive stress generated in the matrix region due to phase transformation expansion in this invention, after being rigidly locked by the solidified weld, is equivalent to constructing a high-rigidity prestressed locking band in situ at the connection boundary between the support member 10 and the base plate 20. Since the matrix region continues to maintain the physical tendency of volume expansion, it applies an inward reverse constraint moment to the main body of the support member 10 through the mating end face 11. This reverse constraint moment can precisely counteract and spontaneously cancel the outward springback bending moment generated by the release of macroscopic residual stress at the bending part in terms of value and direction, so that the two achieve macroscopic mechanical equilibrium at the connection node. Thanks to the ingenious synergy between the aforementioned microscopic thermophysical phase transition and macroscopic mechanical torque, this invention can maintain the three-dimensional dimensional accuracy and structural stability of the corner code assembly before and after welding without the need for any external rigid alignment fixtures.

Claims

1. A method for manufacturing a corner code component, characterized in that, Includes the following steps: S1. Provide a heat-treatable carbon-containing metal sheet, cut into a base plate (20) and bent into a support member (10) with a butt end face (11) and residual stress in the bent part. S2. Use a high-energy beam heat source to perform surface remelting on the docking end face (11) to form a surface texture with micro-roughness. S3. Place the support (10) on the base plate (20) so that the mating end face (11) abuts against the base plate (20) and use the surface texture to define the assembly gap between the mating end face (11) and the base plate (20); S4. Solder is provided and heated at the assembly gap, so that the solder melts into liquid solder and seeps into the assembly gap under capillary action, and the base region of the support (10) adjacent to the mating end face (11) is heated and transformed into austenite. S5. Stop heating to cool the base region to within the martensitic phase transformation temperature range, causing some of the austenite in the base region to transform into martensite and generate volume expansion, causing the assembly gap to shrink and extruding the liquid solder inside, and generating compressive stress in the base region. S6. Before the liquid solder in the assembly gap solidifies, it is heated again to raise the temperature of the base region to and maintain it at the distribution temperature, so that the carbon element in the martensite can be distributed and diffused into the untransformed austenite to form carbon-rich austenite. S7. Stop heating and cool the base region to room temperature so that the carbon-rich austenite in the base region is transformed into a high-toughness structure; and let the liquid solder solidify and form a weld connecting the support (10) and the base plate (20); and use the compressive stress in the base region to constrain the support (10) to resist the springback deformation of the support (10) caused by the internal residual stress.

2. The manufacturing method according to claim 1, characterized in that, In step S2, the surface texture includes micro-channels (30) extending along the thickness direction of the mating end face (11) and micro-protrusions (31) distributed on both sides of the micro-channels (30). In step S4, the liquid solder is directionally capillarily penetrated along the micro-channel (30); In step S5, when the substrate region expands in volume, the micro-protrusion (31) is displaced toward the base plate (20) and pierces into the base plate (20); and the cross-section of the micro-channel (30) contracts to squeeze the liquid solder inside it.

3. The manufacturing method according to claim 1, characterized in that, The carbon mass fraction of the carbon-containing metal sheet is 0.18% to 0.45%.

4. The manufacturing method according to claim 1, characterized in that, In steps S4 and S6, high-frequency induction heating is used as the heat source, and the heating area is limited to a local area of ​​the support (10) adjacent to the mating end face (11).

5. The manufacturing method according to claim 1, characterized in that, In step S5, the martensitic transformation temperature range is between the martensitic transformation start temperature and the martensitic transformation end temperature of the carbon-containing metal plate. In step S6, the distribution temperature is higher than the martensitic transformation start temperature and lower than the bainitic transformation start temperature of the carbon-containing metal plate.

6. The manufacturing method according to claim 1, characterized in that, In step S2, a laser beam or an electron beam is used to continuously scan the mating end face (11), causing the surface metal of the mating end face (11) to melt rapidly and solidify extremely quickly, so as to form the surface texture.

7. The manufacturing method according to claim 1, characterized in that, The support member (10) includes an integrally formed middle plate (12), two side plates (13) and two end plates (14). The two side plates (13) are respectively vertically connected to the opposite sides of the middle plate (12) and are arranged symmetrically. The two end plates (14) are respectively vertically connected to the two side plates (13) on the side that is perpendicular to the middle plate (12), and extend from the two side plates (13) in opposite directions respectively; There are three docking end faces (11). One of the docking end faces (11) is located on the side of the middle plate (12) and is used to abut against the side of the bottom plate (20). The other two docking end faces (11) are located at the bottom edges of the two end plates (14) respectively and are used to abut against the surface of the bottom plate (20).

8. The manufacturing method according to claim 7, characterized in that, The two side plates (13) and the two end plates (14) are provided with mounting holes (15) for external connectors to pass through.

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