Self-riveting microstructure metal composite plate die forming method

Abstract

The present application relates to the technical field of metal composite plate preparation, and particularly relates to a self-riveting microstructure metal composite plate mold pressing forming method. The method comprises the following steps: step S1: preparing a self-riveting microgroove structure on the riveting surface of a hard metal plate; step S2: preparing a self-riveting microconvex structure on the riveting surface of a soft metal plate; step S3: annealing the soft metal plate; step S4: pretreating the riveting surfaces of the soft and hard metal plates; step S5: fixing the riveting surfaces of the soft and hard metal plates face to face, so that the self-riveting microconvex structure and the self-riveting microgroove structure are one-to-one correspondingly inserted to form a laminated plate; step S6: preheating the laminated plate by copper foil cladding; step S7: mold pressing the laminated plate to obtain a composite plate; and step S8: annealing the composite plate. The present application realizes high-strength mechanical riveting and metallurgical bonding dual reinforcement interface of the soft and hard metal composite plate, and improves the comprehensive performance and reliability of the composite plate.

Description

Technical Field

[0001] This invention relates to the field of metal composite plate preparation technology, and in particular to a method for molding self-riveting microstructure metal composite plates. Background Technology

[0002] With the rapid development of industries such as aviation, aerospace, marine, and transportation, the requirements for the performance of metal structural materials are also increasing. In complex and harsh service environments, single metals are no longer sufficient to meet the comprehensive performance requirements of high strength, high stiffness, lightweight, corrosion resistance, and high temperature resistance. Therefore, layered heterogeneous metal composite plates have become an important way to solve this problem.

[0003] The molding and riveting process for dissimilar metal composite plates involves pre-drilling holes in a hard metal substrate and pre-drilling protrusions in a soft metal substrate. This molding process achieves a dual mechanical and metallurgical combination, resulting in a large-area, high-performance connection between the substrate and the cladding. However, current methods suffer from limited hole types, leading to poor metal flow, low filling rate, and significant stress concentration during molding. This results in poor fatigue resistance at the interface of the dissimilar metal composite plate, low hole filling rate, small bonding area, low bonding strength, and susceptibility to interface cracking, hindering the achievement of high-performance and effective bonding. Specifically, existing molding and riveting technologies suffer from the following key problems:

[0004] Pre-formed hole design defects: Existing technologies mostly mold regularly distributed microchannel structures on the surface of hard metal plates (such as steel plates). This type of structure is simple and cannot provide a wedge-shaped bonding force in the normal direction of the bonding surface. Under temperature change and stress load, the interface is prone to cracking, resulting in poor fatigue resistance of the composite plate.

[0005] Processing limitations: When using molding to prepare microchannels on hard metal sheets, there is a "soft friction hard" phenomenon, the molding cutting edge wears severely, the dimensional stability is poor, and the processing cost is high.

[0006] Deformation coordination and interface bonding issues: The thermal deformation coefficients of hard metal plates (steel plates) and soft metals (tin bronze) differ significantly. Existing technologies do not design compensation structures for the difference in thermal expansion coefficients between the two materials, which can easily lead to interface cracking under alternating temperature and stress loads. Some technologies coordinate deformation by introducing an intermediate interlayer (such as an aluminum layer), but this increases the process steps and production costs, and the interface is prone to forming a multi-element diffusion layer, resulting in unstable bonding performance. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a self-riveting microstructure metal composite plate molding method to solve the problems of poor metal flow, low filling rate, easy interface cracking, and low bonding strength during the molding process of hard metal plates and soft metals, thereby achieving high-performance composite of the two materials.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for molding self-riveting microstructured metal composite plates, comprising the following steps:

[0010] Step S1: Prepare a self-riveting microgroove structure on the riveting surface of the hard metal plate;

[0011] Step S2: Prepare a self-riveting micro-protrusion structure on the riveting surface of the soft metal plate;

[0012] Step S3: Anneal the soft metal sheet;

[0013] Step S4: Pre-treat the riveting surfaces of the hard metal plate and the soft metal plate;

[0014] Step S5: The riveting surfaces of the soft metal plate and the hard metal plate are overlapped and fixed face to face, so that the self-riveting micro-protrusion structure of the soft metal plate and the self-riveting micro-groove structure of the hard metal plate are inserted one by one to form a composite plate.

[0015] Step S6: After covering the laminated sheet with copper foil, preheating treatment is performed to enable the self-riveting micro-convex structure of the soft metal sheet to flow plastically.

[0016] Step S7: The preheated laminated plates are molded together. During the molding process, the self-riveting micro-convex structure of the soft metal plate undergoes passive plastic deformation and flows into the self-riveting micro-groove structure of the hard metal plate, thereby achieving a strong mechanical riveting connection at the interface and obtaining a composite plate.

[0017] Step S8: Anneal the composite board.

[0018] In one possible implementation, the self-riveting microgroove structure includes a plurality of grooves spaced apart on the riveting surface of the hard metal plate, wherein the bottom of the grooves is symmetrically provided with oblique grooves I and II on both sides, and the junction between oblique grooves I and oblique grooves II forms a triangular chamfer.

[0019] In one possible implementation, the upper port of the groove is a rectangular structure with rounded corners at the edges of the long side; the bottoms of the inclined grooves I and II are provided with rounded corners.

[0020] In one possible implementation, the upper port of the groove has a length of 2-5 mm and a width of 1.5-3 mm, and the vertical depth of the groove is 2-5 mm; the widths of the inclined groove I and the inclined groove II are 0.6-1.2 mm.

[0021] In one possible implementation, the self-riveting micro-protrusion structure includes a plurality of protrusions spaced apart on the riveting surface of the soft metal plate. The two sides of the protrusion are parallel facade I and facade II. The bottom of the protrusion has a concave arc surface. The concave arc surface smoothly transitions to facade I and facade II through top rounded corner I and top rounded corner II, respectively. When the concave arc surface is molded, it is split open by the cleaving edge of the self-riveting micro-groove structure, so that the protrusion is evenly filled into the inclined groove I and the inclined groove II.

[0022] In one possible implementation, after the protrusion fills into the inclined grooves I and II, thermal deformation compensation joints are left on both sides.

[0023] In one possible implementation, in step S1, the self-riveting microgroove structure on the hard metal plate is electrolytically processed by a forming cathode with vibratory feed; the bottom of the forming cathode is provided with a forming planar stretching body for penetrating into the hard metal plate; the forming cathode has three-dimensional translational and rotational degrees of freedom about the Z-axis.

[0024] In one possible implementation, in step S2, the soft metal sheet is molded on a press using a mold with a microgroove structure, so that a uniformly distributed self-riveting micro-protrusion structure is formed on the riveting surface of the soft metal sheet.

[0025] In step S3, the soft metal plate with the self-riveting micro-protrusion structure is annealed at 650-700°C for 3 hours to eliminate residual stress from the molding process.

[0026] In one possible implementation, in step S4, surface pretreatment is performed by using a steel brush to polish the riveting surfaces of the soft metal plate and the hard metal plate to remove surface oxides and impurities; subsequently, the polished soft metal plate and the hard metal plate are placed in water, hydrochloric acid and acetone in sequence for ultrasonic cleaning to remove surface oil and residual impurities.

[0027] In one possible implementation, in step S6, the copper foil-covered laminated plate is preheated to a temperature of 650–750°C and held at that temperature for 30 seconds; the preheating enables the self-riveting micro-convex structure of the soft metal plate to be shaped and flow.

[0028] In step S7, during the molding process of the preheated laminated sheet, the molding pressure is 105-147 MPa and the holding time is 120-370 seconds.

[0029] In step S8, the composite plate is annealed at a temperature of 550–650°C (the recrystallization temperature of soft metals) for 1 hour.

[0030] The advantages and beneficial effects of this invention are:

[0031] Innovation in self-riveting microstructure design: The outer wedge surface, inner wedge surface, and guide rounded corner of the self-riveting microstructure of hard metal plate work together to solve the problems of wear, deformation incoordination, and interface cracking in the "soft-hard" processing. The top arc surface design of the soft metal microstructure ensures uniform filling.

[0032] Process optimization: Vibration feed electrolytic machining is adopted. Compared with mechanical machining, the microstructure size is small (0.6-1.2mm) and there are no defects. Furthermore, it can be mass-produced by a special electrolytic machine with multi-axis motion of multiple electrolytic cathode heads. Compared with intermediate sandwich technology, no additional process steps are required, thus reducing costs.

[0033] Enhanced performance: Through a dual connection of "mechanical riveting (microstructure interlocking) + metallurgical bonding (subsequent annealing diffusion)," the interfacial bonding strength and fatigue resistance are significantly improved. Furthermore, the length of the tin bronze microstructure is less than the width of the steel plate microstructure, which can compensate for differences in thermal deformation and further suppress cracking.

[0034] Wide applicability: Applicable to tin bronze-steel composite plates, and can be extended to the preparation of other heterogeneous metal composite plates to meet the needs of high-performance composite materials in aerospace and other fields.

[0035] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is an isometric view of the hard metal plate and the soft metal plate before riveting in an embodiment of the present invention;

[0039] Figure 2 This is a cross-sectional view of the hard metal plate and the soft metal plate before riveting in an embodiment of the present invention;

[0040] Figure 3 for Figure 2 Enlarged view of a portion of point A in the middle;

[0041] Figure 4 for Figure 2 Enlarged view of a section at point B in the middle;

[0042] Figure 5This is a schematic diagram of the initial state of the self-riveting microstructure of a hard metal plate and a soft metal plate in an embodiment of the present invention.

[0043] Figure 6 for Figure 5 Enlarged view of a section at point C;

[0044] Figure 7 This is a schematic diagram showing the complete fit between the self-riveting microstructure of the hard metal plate and the soft metal plate in an embodiment of the present invention.

[0045] Figure 8 for Figure 7 AA section view;

[0046] Figure 9 This is an isometric view of the self-riveting microgroove structure for machining hard metal plates in an embodiment of the present invention;

[0047] Figure 10 This is a cross-sectional view of the self-riveting microgroove structure for processing hard metal plates in an embodiment of the present invention;

[0048] Figure 11 This is an isometric view of a rigid metal plate with a self-riveting microgroove structure in an embodiment of the present invention.

[0049] In the diagram: 1. Soft metal plate; 11. Protrusion; 101. Soft riveting surface; 102. Vertical surface I; 103. Vertical surface II; 104. Concave arc surface; 105. Top rounded corner II; 106. Top rounded corner I; 2. Hard metal plate; 21. Groove; 201. Hard riveting surface; 202. Guide rounded corner I; 203. Outer wedge surface I; 204. Bottom rounded corner I; 205. Inner wedge surface I; 206. Cleaver; 207. Inner wedge surface II; 208. Bottom rounded corner II; 209. Outer wedge surface II; 210. Guide rounded corner II; 22. Long side; 23. Wide side; 24. Thickness; 3. Heat deformation compensation joint; 5. Formed cathode; 51. Formed planar tensile body; 501. Inclined surface I; 502. Inclined surface II; 503. Arc surface; 504. Plane. Detailed Implementation

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0052] See Figures 1 to 11 As shown, the present invention provides a method for molding a self-riveting microstructured metal composite plate, comprising the following steps:

[0053] Step S1: Prepare a self-riveting microgroove structure on the riveting surface of the hard metal plate 2;

[0054] Step S2: Prepare a self-riveting micro-protrusion structure on the riveting surface of the soft metal plate 1;

[0055] Step S3: Anneal the soft metal plate 1;

[0056] Step S4: Pre-treat the riveting surfaces of the hard metal plate 2 and the soft metal plate 1;

[0057] Step S5: The riveting surfaces of the soft metal plate 1 and the hard metal plate 2 are overlapped face to face and fixed with iron wire, so that the self-riveting micro-protrusion structure of the soft metal plate 1 and the self-riveting micro-groove structure of the hard metal plate 2 are inserted one by one to form a composite plate.

[0058] Step S6: Wrap the laminated sheet with copper foil to avoid oxidation during the high-temperature treatment, and then perform preheating treatment to enable the self-riveting micro-convex structure of the soft metal sheet to flow plastically.

[0059] Step S7: The preheated laminated plates are molded together. During the molding process, the self-riveting micro-convex structure of the soft metal plate undergoes passive plastic deformation and flows into the self-riveting micro-groove structure of the hard metal plate, thereby achieving a strong mechanical riveting connection at the interface and obtaining a composite plate.

[0060] Step S8: Anneal the composite plate to achieve a metallurgical bond between the soft and hard metals at the joint of the riveted surfaces.

[0061] See Figure 2 and Figure 3 As shown, in an embodiment of the present invention, the self-riveting microgroove structure includes a plurality of grooves 21 spaced apart on the hard riveting surface 201 of the hard metal plate 2. The bottom of the grooves 21 is symmetrically provided with oblique grooves I and II on both sides, and a triangular chamfer 206 is formed at the junction between oblique grooves I and oblique grooves II.

[0062] Preferably, the upper end of the groove 21 has a rectangular structure, and guide fillets I 202 and II 210 are respectively provided at the edges of the two long sides. Guide fillets I 202 and II 210 facilitate the introduction of soft metal during the molding process. Inclined grooves I and II are inclined to both sides in the width direction of the groove 21. The bottom of the inclined groove I is provided with a bottom fillet I 204. The two sides of the bottom fillet I 204 are parallel outer wedge surfaces I 203 and inner wedge surfaces I 205. The upper end of the outer wedge surface I 203 smoothly transitions to the guide fillet I 202. The bottom of the inclined groove II is provided with a bottom fillet II 208. The two sides of the bottom fillet II 208 are parallel outer wedge surfaces II 209 and inner wedge surfaces II 207. The outer wedge surface II 209 smoothly transitions to the guide fillet II 210. An acute-angled chamfer 206 is formed between the inner wedge surface I 205 and the inner wedge surface II 207. Bottom fillet I204 and bottom fillet II208 prevent stress concentration.

[0063] In this embodiment, the upper end of the groove 21 has a length of 2-5 mm, a width of 1.5-3 mm, and a vertical depth of 2-5 mm. The widths of the inclined grooves I and II are 0.6-1.2 mm, meaning the width of inclined groove I is the vertical distance between the outer wedge surface I 203 and the inner wedge surface I 205, and the width of inclined groove II is the vertical distance between the outer wedge surface II 209 and the inner wedge surface II 207. The outer wedge surface I 203 and the outer wedge surface II 209 effectively improve the normal bonding mechanical properties of the joint surface, preventing cracking caused by temperature and stress loads. The cleft 206 formed by the inner wedge surface I 205 and the inner wedge surface II 207 can uniformly distribute plastic deformation during the plastic flow process of the self-riveting micro-convex structure of the soft metal plate 1.

[0064] See Figure 2 , Figures 4 to 7 As shown, in an embodiment of the present invention, the self-riveting micro-protrusion structure includes a plurality of protrusions 11 spaced apart on the soft riveting surface 101 of the soft metal plate 1. The two sides of each protrusion 11 are parallel to each other and perpendicular to the soft riveting surface 101, forming surfaces I 102 and II 103. The bottom of each protrusion 11 has a concave arc surface 104, which smoothly transitions to surfaces I 102 and II 103 via top rounded corners I 106 and II 105, respectively. The concave arc surface 104 helps the self-riveting micro-protrusion structure to be evenly divided into two parts during the joining process. That is, during the molding process, the concave arc surface 104 is split into two parts by the chopping edge 206 of the self-riveting microgroove structure, allowing the protrusions 11 to evenly fill the inclined grooves I and II.

[0065] See Figure 7As shown, in the embodiment of the present invention, the protrusion 11 fills into the inclined groove I and inclined groove II, that is, the vertical surface I 102 and the vertical surface II 103 enter the inclined groove I and inclined groove II respectively, and after the vertical surface I 102 and the vertical surface II 103 are deformed, they fit tightly with the outer wedge surface I 203 and the outer wedge surface II 209 respectively, thereby improving the interlocking stability.

[0066] See Figure 8 As shown, furthermore, thermal deformation compensation joints 3 are left between the two sides of facade I 102 and facade II 103 and the inclined groove, that is, the width of the protrusion 11 is less than the length of the groove 21. The thermal deformation compensation joints 3 can compensate for the stress generated by the two materials under different temperature loads, and avoid fatigue cracks caused by temperature loads and alternating loads.

[0067] Specifically, in step S1, the self-riveting microgroove structure on the hard metal plate 2 is electrolytically processed by the vibrating feed of the forming cathode 5. The forming cathode 5 has three-dimensional translation and rotation around the Z-axis. The axis of the Z-axis is perpendicular to the hard riveting surface 201.

[0068] In step S2, the soft metal plate 1 is molded on a press using a mold with a micro-groove structure, so that a uniformly distributed self-riveting micro-protrusion structure is formed on the soft riveting surface 101 of the soft metal plate 1.

[0069] In step S3, the soft metal plate 1 with the self-riveting micro-protrusion structure is annealed at 650-700°C for 3 hours to eliminate residual stress during the molding process.

[0070] In step S4, surface pretreatment: the riveting surfaces of the soft metal plate 1 and the hard metal plate 2 are polished with a steel brush to remove surface oxides and impurities; then the polished soft metal plate 1 and hard metal plate 2 are placed in water, hydrochloric acid and acetone in sequence for ultrasonic cleaning to remove surface oil and residual impurities.

[0071] In step S6, the copper foil-covered laminated plate is preheated to 650-750°C and held for 30 seconds; preheating enables the self-riveting micro-convex structure of the soft metal plate 1 to be shaped and flow.

[0072] In step S7, during the molding process of the preheated laminated sheet, the molding pressure is 105-147 MPa and the holding time is 120-370 seconds.

[0073] In step S8, after the composite is completed, the copper foil on the surface of the composite board is removed and the surface is polished and cleaned. The polished composite board is then annealed under the following conditions: the recrystallization temperature is 550-650℃ and the temperature is maintained for 1 hour to improve the interfacial bonding performance and mechanical properties of the composite board.

[0074] In this embodiment, the soft metal plate 1 is made of tin bronze, preferably HSn70-1, with a conventional hot working temperature of 650–750°C. This range is suitable for plastic forming processes such as hot forging and hot extrusion. The hard metal plate 2 is made of steel. By appropriately setting the reduction and temperature conditions during the molding process, and combining this with suitable subsequent heat treatment, the diffusion between atoms at the tin bronze and steel interface is promoted, achieving metallurgical bonding and further improving the strength and reliability of the bonding interface.

[0075] In this embodiment, by combining the self-riveting convex microstructure of molding and the hard concave structure of electrolytic machining with the molding process, the problems of large differences in the physical and chemical properties of tin bronze and steel, difficulty in coordinating molding deformation, and easy cracking of the interface are overcome, and a tin bronze-steel bimetallic composite plate with significantly enhanced interface bonding performance is obtained.

[0076] Specifically, see Figures 9 to 11 As shown, the steel plate has a cuboid structure. The self-riveting microgroove structure on the steel plate is fabricated by vibratory feeding electrolytic machining of the forming cathode 5. The forming cathode 5 has four degrees of freedom: movement relative to the long side 22, wide side 23, and thickness 24 of the steel plate, and rotation relative to the hard riveting surface 201 (Z-axis in this paper). The forming cathode 5 processes the various characteristic parts of the self-riveting microgroove structure of the steel plate through a specific motion trajectory. Compared with wire cutting, there are no through-groove defects, such as corrosive gases entering from the joint gap; there is no limitation on the cutting line length of wire cutting; and the processing flexibility is high.

[0077] See Figure 9 and Figure 10 As shown, in an embodiment of the present invention, a forming planar stretching body 51 is inclined at the bottom of the forming cathode 5, and the forming planar stretching body 51 is the portion that penetrates the steel plate. The forming planar stretching body 51 includes mutually parallel inclined surfaces I 501 and II 502. The lower ends of inclined surfaces I 501 and II 502 are connected by a circular arc surface 503, and inclined surfaces I 501 and II 502 are tangent to the two ends of the circular arc surface 503, respectively. The upper ends of inclined surfaces I 501 and II 502 are connected by a plane 504, and the plane 504 is parallel to the bottom of the forming cathode 5.

[0078] Specifically, electrolytic machining is a special machining process based on the principle of electrolytic anodic dissolution, utilizing a shaped cathode to shape and size conductive metal workpieces. During machining, the workpiece acts as the anode, maintaining a gap of 0.1–1 mm with the cathode, and a current of 10–100 A / cm is generated under a 10–24V DC power supply. 2The high current density, combined with an electrolyte flow rate of 6-30 m / s, removes the dissolved products and heat, enabling layer-by-layer material removal and replication of the tool shape. This process is suitable for difficult-to-machine materials such as cemented carbide and high-temperature alloys, and features no mechanical stress, no tool wear, and the ability to machine complex surfaces and thin-walled parts. The machining accuracy reaches ±0.03~0.20 mm, and the surface roughness Ra1.6~0.4 μm.

[0079] Specifically, the forming cathode 5 is subjected to vibration-feed electrolytic machining of a self-riveting microgroove structure on a steel plate, including the following steps:

[0080] Step M1: The forming cathode 5 performs biaxial coupling motion, and the arc surface 503 at the bottom of the forming plane stretching body 51 is used to process the guide fillet I 202 on the hard riveting surface 201 of the hard metal plate 2.

[0081] Step M2: The forming cathode 5 performs a two-axis coupled linear feed motion along the inclined direction of the forming plane stretching body 51 to process the inclined groove I, which includes the outer wedge surface I203, the inner wedge surface I205 and the bottom fillet I204 located at the bottom of the outer wedge surface I203 and the inner wedge surface I205.

[0082] Step M3: The forming cathode 5 drives the forming planar stretching body 51 out of the steel plate area and rotates 180° relative to the Z-axis of the hard riveting surface 201.

[0083] Step M4: The forming cathode 5 performs biaxial coupling motion. The arc surface 503 at the bottom of the forming planar stretching body 51 is used to process the guide fillet 210, which is symmetrical to the guide fillet Ⅰ202, on the hard riveting surface 201. The guide fillet Ⅰ202 and the guide fillet Ⅱ210 are used to guide the tin bronze protrusion 11. At the same time, the guide fillet Ⅰ202 and the guide fillet Ⅱ210 are also used to support the plastic flow of the two side facades Ⅰ102 and Ⅱ103 of the protrusion 11.

[0084] Step M5: The forming cathode 5 performs a two-axis coupled linear feed motion along the inclined direction of the forming plane stretching body 51 to process the inclined groove II, which includes the outer wedge surface II209, the inner wedge surface II207 and the bottom fillet II208 located at the bottom of the outer wedge surface II209 and the inner wedge surface II207.

[0085] See Figure 11 As shown in the embodiments of the present invention, grooves 21 in different directions are processed on the steel plate, which can avoid the problem of insufficient support stiffness in the support surface direction caused by the temperature compensation seam, and ensure that the composite plate has stable support performance in different stress directions, adapting to the mechanical requirements of complex service environments.

[0086] There are other possible alternatives to the technical solution of this invention, such as directly using rolls with micro-convex structures for rolling to form corresponding microgroove structures on the surface of the rigid sheet. However, using rolls for rolling can easily lead to defects such as significant warping, surface roughening, and even microcracks in the sheet, which is detrimental to achieving ideal bonding performance in the subsequent molding process of the bimetallic composite plate. In contrast, the tin bronze-steel bimetallic sheet prepared by the molding method of this invention has a smoother surface and is less prone to the aforementioned defects. Therefore, it can effectively improve the interfacial bonding ability of the bimetallic composite plate in the subsequent molding process, and better achieve the purpose of this invention.

[0087] This invention provides a method for molding a self-riveting microstructured metal composite plate. The method involves electrolytically machining regularly distributed microscale self-riveting microgrooves on the surface of a hard metal plate 2 (e.g., steel plate). The hard metal plate 2 (e.g., steel plate) with the self-riveting microgrooves is then stacked with a soft metal plate 1 (e.g., tin bronze plate). A molding process causes the soft metal plate 1 (e.g., tin bronze) to undergo plastic flow. Under plastic deformation, the soft metal effectively fills and interlocks with the self-riveting microgrooves of the hard metal plate 2, thereby achieving a high-strength mechanical interlock between the soft and hard metals. This mechanical interlock forms a mechanical riveting connection at the riveting interface. Simultaneously, subsequent heat treatment above an appropriate recrystallization temperature further promotes atomic diffusion and metallurgical bonding at the riveting interface, ultimately obtaining a dual-connection interface of mechanical riveting and metallurgical bonding. Ultimately, this invention effectively solves the technical problems of low bonding strength and easy cracking caused by large differences in physical, chemical and mechanical properties, difficulty in deformation coordination and difficulty in interfacial metallurgical reaction during the preparation of tin bronze-steel bimetallic plates. It realizes a dual-strength interface of high-strength mechanical riveting and metallurgical bonding in tin bronze-steel bimetallic composite plates, which significantly improves the comprehensive performance and reliability of composite plates.

[0088] In summary, this invention provides a method for molding self-riveting microstructured metal composite plates. Through a molding process, a self-riveting microgroove structure is fabricated on the surface of a hard metal plate 2 in a single step, achieving large-area integrated manufacturing of the self-riveting microgroove structure. During subsequent molding, this self-riveting microgroove structure effectively promotes mechanical bonding between tin bronze and steel, forming a strong mechanical connection. Combined with subsequent heat treatment, this further achieves a high-quality metallurgical bond between the two materials, thus solving the problems of large differences in physicochemical properties and difficult metallurgical reactions during the molding process of tin bronze-steel composite plates. This significantly improves the interfacial bonding strength, fatigue resistance, and overall mechanical properties of the tin bronze-steel composite plate, making it suitable for applications in aerospace, marine, and transportation fields that require high-performance metal composite plates.

[0089] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for molding self-riveting microstructured metal composite plates, characterized in that, Includes the following steps: Step S1: Prepare a self-riveting microgroove structure on the riveting surface of the hard metal plate; Step S2: Prepare a self-riveting micro-protrusion structure on the riveting surface of the soft metal plate; Step S3: Anneal the soft metal sheet; Step S4: Pre-treat the riveting surfaces of the hard metal plate and the soft metal plate; Step S5: The riveting surfaces of the soft metal plate and the hard metal plate are overlapped and fixed face to face, so that the self-riveting micro-protrusion structure of the soft metal plate and the self-riveting micro-groove structure of the hard metal plate are inserted one by one to form a composite plate. Step S6: After covering the laminated sheet with copper foil, preheating treatment is performed to enable the self-riveting micro-convex structure of the soft metal sheet to flow plastically. Step S7: The preheated laminated plates are molded together. During the molding process, the self-riveting micro-convex structure of the soft metal plate undergoes passive plastic deformation and flows into the self-riveting micro-groove structure of the hard metal plate, thereby achieving a strong mechanical riveting connection at the interface and obtaining a composite plate. Step S8: Anneal the composite board; The self-riveting microgroove structure includes multiple grooves spaced apart on the riveting surface of the hard metal plate. The bottom of the grooves is symmetrically provided with inclined grooves I and II on both sides, and the junction between inclined grooves I and inclined grooves II forms a triangular chamfer. The upper end of the groove is rectangular, and the edge of the long side is provided with a rounded corner; the bottom of the inclined groove I and inclined groove II are provided with a rounded corner. The self-riveting micro-protrusion structure includes multiple protrusions spaced apart on the riveting surface of the soft metal plate. The two sides of the protrusion are parallel facade I and facade II. The bottom of the protrusion has a concave arc surface. The concave arc surface and facade I and facade II are smoothly transitioned to each other by top rounded corner I and top rounded corner II, respectively. During the molding process, the concave arc surface is split open by the cutting edge of the self-riveting microgroove structure, so that the protrusions are evenly filled into the inclined groove I and the inclined groove II.

2. The self-riveting microstructure metal composite plate molding method according to claim 1, characterized in that, The upper end of the groove has a length of 2-5 mm and a width of 1.5-3 mm, and a vertical depth of 2-5 mm; the widths of the inclined groove I and the inclined groove II are 0.6-1.2 mm.

3. The self-riveting microstructure metal composite plate molding method according to claim 1, characterized in that, After the protrusions are filled into the inclined grooves I and II, thermal deformation compensation joints are left on both sides.

4. The self-riveting microstructure metal composite plate molding method according to claim 1, characterized in that, In step S1, the self-riveting microgroove structure on the hard metal plate is electrolytically processed by a forming cathode with vibration feed; the bottom of the forming cathode is inclined and provided with a forming planar stretching body for penetrating into the hard metal plate; the forming cathode has three-dimensional translation and rotation around the Z-axis degrees of freedom.

5. The method for molding self-riveting microstructured metal composite plates according to claim 1, characterized in that, In step S2, the soft metal plate is molded on a molding press using a mold with a micro-groove structure, so that a uniformly distributed self-riveting micro-protrusion structure is formed on the riveting surface of the soft metal plate. In step S3, the soft metal plate with the self-riveting micro-protrusion structure is annealed at 650-700°C for 3 hours to eliminate residual stress from the molding process.

6. The self-riveting microstructure metal composite plate molding method according to claim 1, characterized in that, In step S4, surface pretreatment: the riveting surfaces of the soft metal plate and the hard metal plate are polished with a steel brush to remove surface oxides and impurities; then the polished soft metal plate and the hard metal plate are placed in water, hydrochloric acid and acetone in sequence for ultrasonic cleaning to remove surface oil and residual impurities.

7. The self-riveting microstructure metal composite plate molding method according to claim 1, characterized in that, In step S6, the laminated plate covered with copper foil is preheated to 650-750°C and held for 30 seconds; preheating enables the self-riveting micro-convex structure of the soft metal plate to flow plastically. In step S7, during the molding process of the preheated laminated sheet, the molding pressure is 105-147 MPa and the holding time is 120-370 seconds. In step S8, the composite plate is annealed at a recrystallization temperature of 550–650°C for 1 hour.

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