A precision forming mold and method for spatial arc-shaped thin-walled structures

Abstract

A precision forming manufacturing method for spatial arc-shaped thin-walled structures, relating to the field of high-precision arc-shaped thin-walled structure precision forming, includes an upper die, a lower die, a left punch, a right punch, and locating pins. The upper and lower dies have identical structures and are symmetrical about the XOY plane, while the left and right punches have identical structures and are symmetrical about the YOZ plane. Dedicated holes for locating pins are located on the lines of symmetry of the upper and lower dies. The thin-walled forming structure blank is installed between the upper and lower dies. The locating pins pass through the dedicated locating pin holes and the locating pin holes. The upper and lower dies are fixed by a fixing assembly. The inner arc surfaces of the upper and lower dies are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure, respectively. The left and right punches are connected to both sides of the upper die by fixing assemblies and to the lower die by fixing assemblies. The inner arc surfaces of the left and right punches are designed according to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure, respectively. This method achieves high-precision manufacturing of unit arc-shaped thin-walled structures.

Description

Technical Field

[0001] This invention relates to the field of precision forming and manufacturing of high-precision arc-shaped thin-walled structures, and more particularly to a precision forming mold and method for a novel high-precision self-deploying arc-shaped thin-walled structural unit in space. Background Technology

[0002] Currently, space reconnaissance and surveillance methods are constrained by factors such as electromagnetic wave attenuation in the atmosphere, multi-regional radar coordination, and the limited swath width of high-orbit systems. This severely restricts the loiter time of early warning aircraft, the revisit time of low-orbit constellations, and the surveillance of controlled areas, exacerbating the prominent problems of existing information sensing methods, such as "unclear visibility, inaccurate identification, limited range, and inability to maintain close surveillance." Since the aperture of space optical remote sensors directly determines observation resolution, the future development of high-orbit reconnaissance satellites towards higher resolution inevitably requires the system's equivalent aperture to reach a swath width of hundreds of meters or more. Simultaneously, future microwave reconnaissance satellites are developing towards a new direction of ultra-large aperture and distributed array combinations. Through payload arrays or formations, they aim to achieve reconnaissance functions such as ultra-large virtual apertures on the order of hundreds of meters, ultra-long baseline interferometry on the order of kilometers, large-area moving target detection and imaging, and high-capacity communication. This also creates an urgent need for ultra-large structural support platforms with apertures exceeding hundreds of meters.

[0003] Currently, space deployment mechanisms are the most practical and effective means of constructing large-scale functional support platform structures in orbit. Commonly used deployment mechanisms are mainly classified into six types according to their structural forms: thin-walled tube type, sleeve type, coiled type, articulated type, inflatable deployment type, and tension integrated system type. However, due to the limited internal space envelope size of launch vehicles, the maximum engineering-producible deployment size limit of these commonly used deployment mechanisms is difficult to reach the hundred-meter level, which cannot meet the needs of large-scale space support platforms of hundreds or even thousands of meters for future medium- and high-orbit microwave reconnaissance, space solar power stations, and on-orbit service platforms. The new high-precision self-deploying space mechanism, as a lightweight, high-capacity, passively driven, and highly environmentally adaptable new configuration, and with good system scalability in space, can not only adapt to the requirements of the launch vehicle envelope but also be expanded into different configurations according to the different structural requirements of spacecraft, realizing the construction of the entire structural platform. This can effectively solve the current problem of on-orbit construction of space support platforms of hundreds of meters or more.

[0004] The arc-shaped thin-walled structure involved in this invention is the core functional execution unit module of a novel high-precision self-deploying space mechanism. It mainly consists of two Ω-shaped, ultra-thin arc-shaped plates connected back-to-back, forming an overall X-shape to store elastic potential energy. Simultaneously, numerous parallel micro-grooves of equal width and length are designed at the connection point of the two Ω-shaped arc plates, forming a grid structure to achieve elastic compressibility and geometric coordination of deformation. When the arc-shaped thin-walled structure unit is compressed by an external force, it will have a small envelope size and exhibit a state of elastic potential energy storage in buckling instability. At the same time, the micro-groove configuration of the structure undergoes geometric deformation. When the pre-tightening force in the contracted state is released, the elastic potential energy is converted into kinetic energy, resulting in an unfolded state while maintaining high stiffness. Since the new high-performance self-extension structure is composed of multiple arc-shaped thin-walled structural units arranged in parallel or through each other, the shape and size errors and mechanical properties of a single arc-shaped thin-walled structural unit during the manufacturing process will directly affect the comprehensive performance of the new high-precision self-extension mechanism, such as the deployment orientation accuracy, deployment displacement accuracy, holding stiffness, and storage ratio, through error accumulation. Therefore, higher requirements are placed on the forming and manufacturing of a single arc-shaped thin-walled structure. Summary of the Invention

[0005] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a precision forming mold and method for spatial arc-shaped thin-walled structures, so as to meet the high-precision manufacturing requirements of the arc-shaped thin-walled structure of the core functional execution unit in the above-mentioned novel spatial high-precision self-deploying mechanism.

[0006] Based on the principle of mold forming, a high-precision arc-shaped thin-walled structure mold with positioning and high-temperature shape retention functions is proposed. On this basis, a manufacturing process method for the high-precision arc-shaped thin-walled structure is proposed.

[0007] The technical solution provided in this application is as follows:

[0008] A precision forming mold for spatial arc-shaped thin-walled structures is disclosed, used to form a thin-walled structure blank to obtain an arc-shaped thin-walled structure. The thin-walled structure blank includes two thin plate blanks, which are fixed at the middle by a central weld. Separation welds are located on both sides of the central weld. The surfaces of the two thin plate blanks have microgrooves and locating pin holes. The length direction of the microgrooves is perpendicular to the length direction of the central weld. The locating pin holes are located at the central weld position of the thin plate blanks. The mold includes an upper die, a lower die, a left punch, a right punch, and locating pins. The upper and lower dies have identical structures, and their spatial relative installation positions are symmetrical about the XOY plane (horizontal plane). The left and right punches... The molds have identical structures, and their spatial relative installation positions are symmetrical about the YOZ plane (vertical plane). There are multiple dedicated locating pin holes on the symmetry lines of the upper and lower dies. The thin-walled forming structure blank is installed between the upper and lower dies. The locating pins pass through the dedicated locating pin holes and the locating pin holes. The upper and lower dies are fixed together by a fixing component. The inner arc surfaces of the upper and lower dies are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure, respectively. The left and right punches are connected to both sides of the upper die by fixing components, and the left and right punches are connected to the lower die by fixing components. The inner arc surfaces of the left and right punches are designed according to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure, respectively.

[0009] After the left and right punches are connected to the upper and lower dies by twelve sets of fixing components, their internal curved space perfectly fits the upper, lower, left, and right curved surfaces of the arc-shaped thin-walled structure, thereby achieving high-precision shape control of the arc-shaped thin-walled structure. Applicable molding materials include titanium alloys, stainless steel, and other high-strength metal materials.

[0010] Preferably, the upper die includes an upper connecting structure and an upper curved surface structure. The upper connecting structure is connected to the side of the upper curved surface structure opposite to the lower die, and is also connected to the two ends of the upper curved surface structure facing the left punch and the right punch, respectively. The lower die includes a lower connecting structure and a lower curved surface structure. The lower connecting structure is connected to the side of the lower curved surface structure opposite to the upper die, and is also connected to the two ends of the lower curved surface structure facing the left punch and the right punch, respectively. The upper connecting structure and the lower connecting structure are used to connect the left punch and the right punch through a fixing component. The upper curved surface structure and the lower curved surface structure have the same thickness.

[0011] Preferably, the left punch includes a left mounting plate and a left forming structure. The left mounting plate is connected to the left forming structure on the side away from the blank of the thin-walled forming structure. The left mounting plate is connected to the upper die and the lower die on the side away from the right punch via a fixing component. The right punch includes a right mounting plate and a right forming structure. The right mounting plate is connected to the right forming structure on the side away from the blank of the thin-walled forming structure. The right mounting plate is connected to the upper die and the lower die on the side away from the left punch via a fixing component.

[0012] Preferably, the microgroove structure on the arc-shaped thin-walled structure is processed by femtosecond laser cutting. By controlling the process parameters such as femtosecond laser pulse energy, pulse width, scanning speed, focal length and spot diameter, the microgroove is processed on two rectangular planar thin-walled metal plates of the same size with a thickness of 0.1-1mm. The relative position between the spot and the planar thin-walled plate is adjusted by a precision motion clamp, so as to realize the cold processing of the microgroove features and positioning pin holes of the arc-shaped thin-walled structure, avoid the formation of heat-affected zone, reduce thermal stress and damage to the base material, and suppress the deformation of the planar thin-walled plate blank.

[0013] Preferably, a pulsed laser is used to weld two planar thin-walled plates that have already undergone microgroove processing. The welding position is 1.5-2.5 mm inside the separation line of the arc-shaped curved surfaces at both ends of the theoretical arc-shaped thin-walled structure and along the symmetrical line of the separation line at both ends of the planar thin-walled plate. By adjusting the galvanometer, the laser spot is controlled to move along the weld direction on the planar thin-walled plate and oscillate around both sides of the weld at a certain frequency. By adjusting the process parameters such as welding speed, laser power, oscillation frequency, oscillation radius, and beam attitude, a laser oscillation lap welding process window for low-stiffness ultra-thin structures is established to obtain a well-formed welded joint with a wide macroscopic microstructure of 0.1-0.8 mm, thereby achieving the purpose of suppressing weld defects and controlling the microstructure.

[0014] Preferably, the spatial arc-shaped thin-walled structure is formed using a combination mold. The curved surfaces at both ends of the upper and lower concave molds are offset outward relative to the upper and lower theoretical arc surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin plate blank. Similarly, the curved surfaces on the left and right punches are offset outward relative to the left and right theoretical arc surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin plate blank. This ensures that the internal curved surface space after the punch and die combination is perfectly fitted with the upper, lower, left, and right arc surfaces of the arc-shaped thin-walled structure, achieving precise form preservation of the arc-shaped thin-walled structure.

[0015] Preferably, the precision forming mold for the arc-shaped thin-walled structure is connected as a whole using bolts and nuts. Specifically, the upper and lower dies are connected by 4 pairs of bolts and nuts (fixing components); the left punch and upper die are connected by 3 pairs of bolts and nuts (fixing components); the left punch and lower die are connected by 3 pairs of bolts and nuts (fixing components); the right punch and upper die are connected by 3 pairs of bolts and nuts (fixing components); and the right punch and upper die are connected by 3 pairs of bolts and nuts (fixing components), totaling 16 connection points. All bolts and nuts are of the same specification and can be interchanged, offering advantages such as convenient assembly and disassembly and high connection reliability. Thermal expansion washers expand upon heating to offset the axial expansion of the fixing bolts when heated.

[0016] Preferably, the installation sequence of the punch, die, and welded thin plate blank is controlled. Utilizing the deformation characteristics of the weld seam of the thin plate blank under stress, the upper and lower dies and the welded thin plate blank are first positioned and installed using locating pins. Then, four pairs of fixing bolts, thermal expansion washers, and fixing nuts are installed in sequence. By pre-setting the torque wrench threshold, it is ensured that the distance between the upper and lower die plane areas is exactly twice the wall thickness of the thin plate blank after the fixing nuts are tightened. Since the average thickness of the weld seam area after high-speed oscillating laser welding is slightly greater than twice the wall thickness of the thin plate blank, the upper and lower sides of the thin plate blank at both ends will warp and separate by 1-3mm after the weld seam in the upper and lower die plane areas is compressed, facilitating the insertion of the left and right punches. Finally, 12 pairs of fixing bolts, expansion washers, and fixing nuts are installed to connect and fix the left and right punches and the upper and lower dies. This precision mold features a highly reliable and easily disassembled connection design.

[0017] Preferably, the arc-shaped thin-walled structure is processed using an integrated thermoforming process combining the arc-shaped thin-walled structure and the conformal mold. The conformal mold and the flat thin-plate blank installed inside it are first annealed together to eliminate thermal stress and defects such as porosity and cracks in the weld after continuous laser pulse welding. After annealing, they are subjected to high-temperature thermoplastic molding to achieve precision forming of the arc-shaped thin-walled structure. Finally, they are subjected to low-temperature annealing to eliminate thermal stress inside the arc-shaped thin-walled structure material after thermoplastic molding and improve the resilience of the arc-shaped thin-walled structure.

[0018] Preferably, the punch, die, and locating pin are made of carbon fiber reinforced ceramic matrix composites such as C / C composites, C / SiC composites, and C / ZrC composites, which have low coefficients of thermal expansion, high thermal conductivity, high temperature resistance, and high rigidity. This controls the amount of upward expansion of the punch and die surfaces along the normal direction during the thermoforming of the arc-shaped thin-walled structure, avoiding large compressive forces on the arc-shaped thin-walled structure inside the mold, thereby ensuring the wall thickness and shape accuracy of the arc-shaped thin-walled structure.

[0019] Preferably, the junction of the two symmetrical arc surfaces on the punch is provided with a radius of R0.3 to 0.6. On the one hand, this avoids the junction of the arc surfaces being too sharp, preventing the punch from scratching the arc-shaped thin-walled structure during assembly. At the same time, the radius, which is 1-3mm lower than the separation distance of the upper and lower thin-walled plates, helps the left and right punches to be smoothly inserted between the upper and lower thin-walled plates. On the other hand, the radius of R0.3 to 0.6 ensures that the junction of the arc surfaces maintains a certain distance from the weld at the separation point of the upper and lower thin-walled arc surfaces in the arc-shaped thin-walled structure. This provides an expansion gap for the arc-shaped thin-walled structure during thermoforming, and can prevent the weld from tearing due to the pressure of the punch after the arc-shaped thin-walled structure expands.

[0020] Preferably, the cross-section of the double-sided curved surface structure of the die is designed to be of equal thickness. This ensures that during the integrated thermoforming process of the arc-shaped thin-walled structure, the small expansion caused by heat at the curved surface of the die is consistent along the normal direction of the curved surface. This directly controls the magnitude and direction of the compressive stress exerted by the die on each position of the arc-shaped thin-walled surface during the thermoforming process to remain consistent. This ensures the shape and position accuracy of the curved surface of the formed arc-shaped thin-walled structure and avoids the weld tearing problem caused by excessive deformation at the weld seam 1.5-2.5mm inside the separation line of the arc-shaped curved surfaces at both ends of the arc-shaped thin-walled structure.

[0021] Preferably, since the fixing bolts connecting the die and punch expand and elongate along the bolt axis during thermoforming, the preload of the fixing bolts on the die and punch decreases. This directly leads to uneven compressive stress on the arc-shaped thin-walled structure during thermoforming. On the one hand, it cannot guarantee the uniformity of the cross-sectional thickness of the arc-shaped thin-walled structure. On the other hand, it will cause unevenness of the internal metal structure after thermoforming, seriously affecting the mechanical properties of the arc-shaped thin-walled structure and the consistency and stability of its elastic potential energy storage and release during use. It cannot guarantee the comprehensive performance of the new high-performance self-stretching structure composed of multiple parallel or intersecting arc-shaped thin-walled structural units, such as the unfolding direction accuracy, unfolding displacement accuracy, maintaining stiffness, and packing ratio. Therefore, elastic washers are designed and installed on the fixing bolts to ensure that the bolts maintain a certain preload during thermoforming and control the compressive stress on the arc-shaped thin-walled structure by the die and punch to remain constant.

[0022] Preferably, conventional mechanical elastic washers suffer from thermal failure under long-term high-temperature conditions. Their released elastic force gradually decreases with increasing temperature and time. This means that during the thermoforming process of curved thin-walled structures, conventional mechanical elastic washers cannot guarantee a constant preload on the fixing bolts, and consequently, cannot control the uniform and constant compressive stress exerted by the die and punch on the curved thin-walled structure. Therefore, based on the relationship between the expansion of the fixing bolts and temperature, a thermally expanding elastic washer is designed to replace the conventional mechanical elastic washer structure. The washer material is selected from nickel-based alloys, molybdenum alloys, and chromium... Special heat-resistant materials such as alloys, which possess certain rigidity, stable coefficients of thermal expansion, and a wide linear expansion temperature range, are used to rationally plan and design the inner diameter, outer diameter, and thickness of the thermal expansion elastic washer. This ensures that during the thermoforming process, the expansion elongation of the thermal expansion elastic washer along the axial direction of the fixing bolt can offset the expansion elongation of the fixing bolt along its own axial direction, guaranteeing that the bolt maintains a constant preload during thermoforming. This controls the compressive stress of the die and punch on the arc-shaped thin-walled structure to remain constant, ensuring the consistency and stability of the mechanical properties of the formed arc-shaped thin-walled structure and its own elastic potential energy storage and release.

[0023] In summary, this application includes at least the following beneficial technical effects:

[0024] 1. A precision forming mold structure for a highly elastic spatial arc-shaped thin-walled structure is provided, comprising an upper die, a lower die, a left punch, a right punch, positioning pins, fixing bolts, fixing nuts, and thermal expansion washers. The arc surfaces at both ends of the upper and lower dies are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure, respectively, and are offset outward relative to the upper and lower theoretical arc surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin-walled blank. The arc surfaces on the left and right punches are designed according to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure, respectively, and are offset outward relative to the left and right theoretical arc surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin-walled blank. This allows for high-precision shape control of the arc-shaped thin-walled structure and is suitable for forming arc-shaped thin-walled structures made of various high-strength metal materials such as titanium alloys and stainless steel. The mold is connected by bolts and nuts, with consistent bolt and nut specifications throughout, allowing for interchangeability and offering advantages such as convenient assembly and disassembly and high connection reliability.

[0025] 2. The microgroove structure on the arc-shaped thin-walled structure is processed by femtosecond laser cutting. By controlling the process parameters, the microgroove is processed on the rectangular planar thin-walled metal sheet. With the characteristics of femtosecond laser cutting cold processing, the formation of the heat-affected zone is reduced, the thermal stress and thermal damage of the base material are reduced, and the deformation of the planar thin sheet blank is suppressed.

[0026] 3. Two planar thin-walled plates with microgrooves already processed are welded using pulsed laser. By adjusting process parameters such as welding speed, laser power, oscillation frequency, oscillation radius, and beam attitude, a laser oscillation lap welding process window for low-stiffness ultra-thin structures is established to obtain a well-formed welded joint with a wide macroscopic microstructure of 0.1-0.8mm, thereby suppressing weld defects and controlling the microstructure.

[0027] 4. Based on the structural characteristics of the punch and die, a method for using a precision forming mold is provided. Taking advantage of the fact that the average thickness of the weld seam area after high-speed oscillating laser welding is slightly greater than twice the wall thickness of the thin plate blank, when the upper and lower dies are installed, the weld seam of the thin plate in the mold plane area will be subjected to pressure and will cause 1-3mm of edge separation. At the same time, it is convenient to insert the left and right punches, which is beneficial to the installation of the mold and the thin plate blank.

[0028] 5. A precision forming manufacturing process for a highly elastic spatial arc-shaped thin-walled structure is provided. The mold and the flat thin plate blank installed inside it are subjected to low-temperature annealing to eliminate the thermal stress inside the weld after continuous laser pulse welding, as well as defects such as pores and cracks. After annealing, they are subjected to high-temperature thermoplastic molding to achieve precision forming of the arc-shaped thin-walled structure. Finally, they are subjected to low-temperature annealing to eliminate the thermal stress inside the arc-shaped thin-walled structure material after thermoplastic molding. This can improve the resilience of the spatial arc-shaped thin-walled structure and ensure its dimensional accuracy, shape accuracy, mechanical properties, microstructure and other mechanical properties.

[0029] 6. Carbon fiber reinforced ceramic matrix composites such as C / C composites, C / SiC composites, and C / ZrC composites, which have low coefficients of thermal expansion, high thermal conductivity, high temperature resistance, and high rigidity, are selected as the manufacturing materials for punches, dies, and locating pins. This reduces the amount of upward expansion of the punch and die surfaces along the normal direction during the thermoforming of the arc-shaped thin-walled structure, avoids large compressive forces on the arc-shaped thin-walled structure inside the mold, and ensures the dimensional accuracy of the wall thickness and shape of the arc-shaped thin-walled structure.

[0030] 7. The junction of the two symmetrical arc surfaces on both sides of the punch is designed with a radius of R0.3 to 0.6. This avoids the junction being too sharp and prevents the punch from scratching the arc-shaped thin-walled structure during assembly. At the same time, the radius, which is 1-3mm lower than the upper and lower thin-walled plates, helps the left and right punches to be smoothly inserted between the upper and lower thin-walled plates. In addition, the radius of R0.3 to 0.6mm ensures that the junction of the arc surfaces is kept at a certain distance from the weld at the junction of the upper and lower thin-walled arc surfaces of the arc-shaped thin-walled structure. This provides an expansion gap for the arc-shaped thin-walled structure during thermoforming and prevents the weld from tearing due to the punch's pressure after the arc-shaped thin-walled structure expands.

[0031] 8. The double-sided equal-thickness cross-section structure of the die ensures that the small thermal expansion of the die surface during thermoforming is consistent along the normal direction of the surface. This directly controls the magnitude and direction of the compressive stress of the die on the arc-shaped thin-walled surface during thermoforming, ensuring the shape and position accuracy of the arc-shaped thin-walled structure after forming. It also avoids the weld tearing problem caused by excessive deformation at the weld seam 1.5-2.5mm inside the separation line of the arc-shaped surface at both ends of the arc-shaped thin-walled structure.

[0032] 9. A thermal expansion elastic washer, specifically designed for thermoforming applications, is installed at the end of the fixing bolt head. The washer material is selected from heat-resistant special alloy materials such as nickel-based alloys, molybdenum alloys, and chromium alloys, which have certain rigidity, stable coefficients of thermal expansion, and wide linear expansion temperature ranges. Utilizing the principle of thermal expansion, the expansion elongation of the thermal expansion elastic washer along the axial direction of the fixing bolt during thermoforming can offset the expansion elongation of the fixing bolt along its own axial direction, ensuring that the bolt maintains a constant preload during thermoforming. This solves the problem of unstable bolt preload caused by the thermal failure of conventional mechanical elastic washers in long-term high-temperature environments. It also controls the compressive stress of the die and punch on the arc-shaped thin-walled structure to remain constant, ensuring the consistency and stability of the mechanical properties of the arc-shaped thin-walled structure after forming, as well as the storage and release of its own elastic potential energy. This improves the overall performance of the new high-performance self-extending structure composed of multiple parallel or intersecting arc-shaped thin-walled structural units, including the accuracy of deployment direction, deployment displacement, stiffness retention, and packing ratio. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the arc-shaped thin-walled structure of the core functional execution unit in the novel high-precision self-deploying space mechanism;

[0034] Figure 2 This is a schematic diagram of a high-precision arc-shaped thin-walled structure manufacturing mold with positioning and high-temperature shape retention functions;

[0035] Figure 3 This is an exploded schematic diagram of the mold installation method during the thermoforming process of a spatial arc-shaped thin-walled structure.

[0036] Explanation of reference numerals: 1. Arc-shaped thin-walled structure; 1-1. Upper Ω-shaped arc-shaped thin plate; 1-2. Lower Ω-shaped arc-shaped thin plate; 1-3. Middle weld; 1-4. Arc-shaped structure separation weld; 1-5. Microgroove structure; 1-6. Locating pin hole;

[0037] 2. High-precision arc-shaped thin-walled structure manufacturing mold; 2-1. Upper concave mold; 2-2. Lower concave mold; 2-3. Left punch; 2-4. Right punch; 2-5. Positioning pin; 2-6. Fixing bolt; 2-7. Thermal expansion washer; 2-8. Fixing nut. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0039] refer to Figure 1 The core functional execution unit of the novel high-precision self-deploying space mechanism, the arc-shaped thin-walled structure 1, consists of an upper Ω-shaped arc-shaped thin plate 1-1 and a lower Ω-shaped arc-shaped thin plate 1-2. The two Ω-shaped arc-shaped thin plates are connected back-to-back by a central weld 1-3 distributed along the axis of symmetry of the Ω-shaped arc-shaped thin plates and two linear arc-shaped separation welds 1-4 distributed 5-10 mm inside the separation line of the arc-shaped curved surfaces of the two Ω-shaped thin plates. The arc-shaped thin-walled structure 1 is X-shaped overall, enabling the storage of elastic potential energy. Two parallel columns of microgroove matrices (micro-grooves) with the same width and length are distributed in the planar area where the two Ω-shaped arc-shaped plates are in contact back-to-back. The length and width of the groove are designed according to the actual requirements for storing and releasing elastic potential energy, forming a microgroove structure 1-5. This structure can achieve elastic compressibility and geometric coordination of deformation. When the arc-shaped thin-walled structure 1 is compressed by an external force, it will have a small envelope size and exhibit a state of elastic potential energy storage in buckling instability. At the same time, the configuration of the microgroove structure 1-5 exhibits geometric deformation. When the pre-tightening force is released in the contracted state, the elastic potential energy is converted into kinetic energy, exhibiting an unfolded state while maintaining high stiffness. The positioning pin holes 1-6 located on the axis of symmetry of the two Ω-shaped arc-shaped thin plates are process holes. Combined with the positioning pins, they constrain the arc-shaped thin-walled structure 1. Figure 2 The internal spatial position of the high-precision arc-shaped thin-walled structure manufacturing mold 2.

[0040] The origin O is defined as the midpoint of the upper middle weld 1-3 of the arc-shaped thin-walled structure 1. The length direction of the middle weld 1-3 is defined as the Y direction. The X direction is parallel to the middle plane of the arc-shaped thin-walled structure 1 and perpendicular to the Y direction. The Z direction is perpendicular to both the X and Y directions.

[0041] refer to Figure 2 and Figure 3 This application discloses a precision forming mold 2 for a spatial arc-shaped thin-walled structure, which consists of an upper concave mold 2-1, a lower concave mold 2-2, a left convex mold 2-3, and a right convex mold 2-4. The upper die 2-1 and the lower die 2-2 have the same structure and are symmetrical about the XOY (horizontal plane). The inner arc surfaces of the upper and lower dies are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure 1, respectively. At the same time, the cross-section of the curved surface structure on both sides of the die is designed to be of equal thickness. This controls the compressive stress of the die on the arc surface of the arc-shaped thin-walled structure 1 at each position during the thermoforming process to keep the magnitude and direction consistent, ensuring the surface shape and position accuracy of the arc-shaped thin-walled structure 1 after forming, and avoiding the weld tearing problem caused by excessive deformation of the arc-shaped structure separation weld at both ends of the arc-shaped thin-walled structure 1. There are four special holes for positioning pins on the axis of symmetry of the two dies. The spatial positional relationship between the upper and lower dies and the arc-shaped thin-walled structure 1 is ensured by positioning pins 2-5. They are connected by four sets of fixing components, including fixing bolts 2-6, thermal expansion washers 2-7 and fixing nuts 2-8. The left punch 2-3 and the right punch 2-4 have the same structure and are symmetrical about the YOZ (vertical plane). The inner arc surfaces of the left and right punches are designed according to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure, respectively. At the junction of the arc surfaces symmetrical about the horizontal plane on both sides of the punch, a radius of R0.3 to 0.6 is provided to prevent the punch from scratching the arc-shaped thin-walled structure during assembly. This also ensures that a certain distance is maintained between the punch and the upper and lower thin-walled arc surfaces of the arc-shaped thin-walled structure 1, thus protecting the arc-shaped thin-walled structure 1. An expansion gap is reserved during the thermoforming process to prevent weld tearing caused by the extrusion of the arc-shaped thin-walled structure 1 by the punch after its own expansion. When the left and right punches are installed, they are each connected to the upper die through 3 sets of fixing components, and the left and right punches are each connected to the lower die through 3 sets of fixing components. This ensures that the internal curved space of the high-precision arc-shaped thin-walled structure manufacturing mold 2 fits perfectly with the upper, lower, left, and right arc surfaces of the arc-shaped thin-walled structure 1 after assembly, achieving precise shape control of the arc-shaped thin-walled structure 1 during the thermoforming process.

[0042] The high-precision arc-shaped thin-walled structure manufacturing mold is applicable to molding materials including titanium alloy, stainless steel and other high-strength metal materials.

[0043] refer to Figure 3This invention provides a detailed description of a precision forming and manufacturing method for a spatial arc-shaped thin-walled structure, using specific examples of precision forming and manufacturing of TA15 titanium alloy arc-shaped thin-walled structures. It should be noted that this process is not only applicable to titanium alloys, but also to various high-strength metals such as aluminum alloys and stainless steel. Therefore, based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0044] (1) The microgroove structure 1-5 and the positioning pin hole 1-6 on the TA15 titanium alloy arc-shaped thin-walled structure 1 are processed by femtosecond laser cutting. By controlling the process parameters such as femtosecond laser pulse energy, pulse width, scanning speed, focal length and spot diameter, the relative position between the spot and the planar thin-walled plate is adjusted. The microgroove and positioning pin hole processing are carried out on two TA15 titanium alloy planar thin-walled metal plates with the same size in the thickness range of 0.1-1mm. With the characteristics of femtosecond laser cutting cold processing, the formation of heat-affected zone is reduced, the thermal stress and thermal damage of the base material are reduced, the deformation of the planar thin plate blank is suppressed, and the cold processing of the microgroove structure 1-5 and the positioning pin hole 1-6 of the TA15 titanium alloy arc-shaped thin-walled structure 1 is realized.

[0045] (2) Two TA15 titanium alloy planar thin-walled plates with microgroove structure 1-5 and positioning pin hole 1-6 already processed are welded using pulsed laser to form a central weld 1-3 and two arc-shaped separation welds 1-4, thus obtaining a TA15 titanium alloy thin-walled forming structure blank. By adjusting the galvanometer, the laser spot is controlled to move along the weld direction on the planar thin-walled plate and oscillate around the weld at a certain frequency on both sides. By adjusting the process parameters such as welding speed, laser power, oscillation frequency, oscillation radius, and beam attitude, a low-stiffness ultra-thin structure laser oscillation lap welding process window is established to obtain a 0.1-0.8mm wide macroscopic micro-forming welded joint, thereby suppressing weld defects and controlling the weld microstructure.

[0046] (3) First, the upper die 2-1, lower die 2-2, and the welded TA15 titanium alloy thin-walled forming structure blank are positioned and installed using four positioning pins 2-5. Then, four sets of fixing bolts 2-6, thermal expansion washers 2-7, and fixing nuts 2-8 are installed sequentially. By pre-setting the torque wrench threshold, it is ensured that after tightening the fixing nuts 2-6, the distance between the upper and lower die plane areas is exactly twice the wall thickness of the thin-walled blank. Utilizing the stress deformation characteristics of the weld seam of the TA15 titanium alloy thin-walled blank, the... The average thickness of the weld seam area after high-speed oscillating laser welding is slightly greater than twice the wall thickness of the thin plate blank. This causes the upper and lower sides of the thin plate blank at both ends to warp and separate by 1-3mm after the weld seam in the upper and lower die plane area is compressed. This facilitates the insertion of the left and right punches. Finally, 12 sets of fixing bolts 2-6, thermal expansion washers 2-7 and fixing screws 2-8 are installed to connect and fix the left and right punches and the upper and lower dies. The fixing nuts 2-6 are tightened as required.

[0047] (4) The TA15 titanium alloy arc-shaped thin-walled structure 1 is processed using an integrated thermoforming process. First, the high-precision arc-shaped thin-walled structure manufacturing mold 2 and the TA15 titanium alloy thin-walled forming structure blank installed inside it are placed in a muffle furnace, and the muffle furnace is evacuated, with the pressure controlled at 10. -1 -10 -7To prevent oxidation and hydrogen embrittlement of the TA15 titanium alloy sheet surface caused by O2, H2, and other components in the air during subsequent hot forming processes, the surface composition and microstructure of the formed TA15 titanium alloy arc-shaped thin-walled structure 1 are controlled to be consistent with the internal structure, ensuring the mechanical properties of the TA15 titanium alloy arc-shaped thin-walled structure 1. Then, the internal temperature of the muffle furnace is set to 550-600℃ for annealing of the TA15 titanium alloy sheet to eliminate continuous excitation. After pulsed welding, residual stress, porosity, cracks, and other defects inside the weld are reduced, improving the mechanical properties and corrosion resistance of the weld area. Annealing time is controlled within the range of 1-1.5 hours. After reaching the annealing time, the muffle furnace temperature is raised to 800-1000℃, and the TA15 titanium alloy sheet in the high-precision arc-shaped thin-walled structure manufacturing mold 2 is subjected to high-temperature thermoplastic forming. The time needs to be precisely controlled within the range of 10-15 minutes to ensure sufficient deformation and uniform distribution of the grain structure inside the TA15 titanium alloy sheet, while avoiding prolonged high-temperature forming of the grains. The growth of TA15 titanium alloy thin plates during thermoforming at high temperatures leads to a series of problems, including decreased mechanical properties, embrittlement tendency, reduced corrosion resistance, poor material microstructure uniformity and consistency, and increased molding difficulty. The temperature is then slowly reduced in the muffle furnace to 250-450℃ over a period of 0.5-1 hour to minimize the accumulation of internal thermal stress caused by rapid temperature changes. Finally, the temperature is maintained at this level for 1.5-2 hours to eliminate internal thermal stress in the thermoformed arc-shaped thin-walled structure through low-temperature annealing, thereby improving the performance of the arc-shaped thin-walled structure. After completing the hot forming process of the TA15 titanium alloy arc-shaped thin-walled structure 1, the muffle furnace is closed, and the high-precision arc-shaped thin-walled structure manufacturing mold 2 and the TA15 titanium alloy arc-shaped thin-walled structure 1 inside are allowed to cool naturally to room temperature. Then, the vacuum environment inside the muffle furnace is restored to the atmospheric environment. Then, the 16 sets of fixing bolts, thermal expansion washers and fixing screws on the high-precision arc-shaped thin-walled structure manufacturing mold 2 are removed in sequence, and the TA15 titanium alloy arc-shaped thin-walled structure 1 that has completed the hot forming process is taken out. Thus, the entire life cycle process of the arc-shaped thin-walled structure 1 is completed. It should be noted that the thermal expansion washer 2-7 installed at the end of the head of the fixing bolt 2-6 is the key to ensuring the successful thermoforming of the TA15 titanium alloy arc-shaped thin-walled structure 1. Utilizing the principle of thermal expansion of the thermal expansion washer 2-7 under heat, its expansion along the axial direction of the fixing bolt 2-6 can offset the expansion along its own axial direction of the fixing bolt 2-6, ensuring that the bolt maintains a constant preload during the thermoforming process. This solves the problem of unstable bolt preload caused by the thermal failure of conventional mechanical elastic washers in long-term high-temperature environments. It also controls the compressive stress of the die and punch on the arc-shaped thin-walled structure to remain constant, ensuring the consistency and stability of the mechanical properties of the TA15 titanium alloy arc-shaped thin-walled structure 1 after forming, as well as its own elastic potential energy storage and release.

[0048] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0049] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

Claims

1. A precision forming mold for a spatial arc-shaped thin-walled structure, characterized in that: This is used to form an arc-shaped thin-walled structure (1) from a thin-walled forming structure blank. The thin-walled forming structure blank includes two thin plate blanks, which are fixed in the middle by a central weld (1-3). The two thin plate blanks have separation welds (1-4) on both sides of the central weld (1-3). The surfaces of the two thin plate blanks have microgrooves (1-5) and positioning pin holes (1-6). The length direction of the microgrooves (1-5) is perpendicular to the central weld (1-3). Along the length direction of the sheet metal, the locating pin hole (1-6) is located at the weld (1-3) in the middle of the sheet metal blank. The mold includes an upper die (2-1), a lower die (2-2), a left punch (2-3), a right punch (2-4), and a locating pin (2-5). The upper die (2-1) and the lower die (2-2) have the same structure, and their spatial relative installation positions are symmetrical about the XOY plane. The left punch (2-3) and the right punch (2-4) have the same structure. The spatial installation positions are symmetrical about the YOZ plane. Multiple locating pin holes are located on the symmetry line of the upper die (2-1) and lower die (2-2). The thin-walled forming blank is installed between the upper die (2-1) and lower die (2-2). Locating pins (2-5) pass through the locating pin holes and locating pin holes (1-6). The upper die (2-1) and lower die (2-2) are fixed together by a fixing assembly. -2) The inner arc surfaces are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure (1); the left punch (2-3) and the right punch (2-4) are connected to the two sides of the upper die (2-1) through fixing components, and the left punch (2-3) and the right punch (2-4) are connected to the lower die (2-2) through fixing components. The inner arc surfaces of the left punch (2-3) and the right punch (2-4) are designed according to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure.

2. The precision forming mold for a spatial arc-shaped thin-walled structure according to claim 1, characterized in that: The upper die (2-1) includes an upper connecting structure and an upper curved surface structure. The upper connecting structure is connected to the side of the upper curved surface structure away from the lower die (2-2), and the upper connecting structure is connected to the two ends of the upper curved surface structure facing the left punch (2-3) and the right punch (2-4), respectively. The lower die (2-2) includes a lower connecting structure and a lower curved surface structure. The lower connecting structure is connected to the side of the lower curved surface structure away from the upper die (2-1), and the lower connecting structure is connected to the two ends of the lower curved surface structure facing the left punch (2-3) and the right punch (2-4), respectively. The upper connecting structure and the lower connecting structure are used to connect the left punch (2-3) and the right punch (2-4) through a fixing component. The upper curved surface structure and the lower curved surface structure are of equal thickness.

3. The precision forming mold for a spatial arc-shaped thin-walled structure according to claim 1, characterized in that: The left punch (2-3) includes a left mounting plate and a left forming structure. The left mounting plate is connected to the left forming structure on the side away from the blank of the thin-walled forming structure. The left mounting plate is connected to the upper die (2-1) and the lower die (2-2) on the side away from the right punch (2-4) by a fixing component. The right punch (2-4) includes a right mounting plate and a right forming structure. The right mounting plate is connected to the right forming structure on the side away from the blank of the thin-walled forming structure. The right mounting plate is connected to the upper die (2-1) and the lower die (2-2) on the side away from the left punch (2-3) by a fixing component.

4. The precision forming mold for a spatial arc-shaped thin-walled structure according to claim 3, characterized in that: Both the left and right forming structures have an upper arc surface and a lower arc surface. The upper and lower arc surfaces are symmetrical about the contact surfaces of the two thin sheet blanks. The contact surfaces are XOY surfaces. A rounded corner structure with R0.3 to 0.6 is provided at the junction of the upper and lower arc surfaces.

5. The precision forming mold for a spatial arc-shaped thin-walled structure according to claim 1, characterized in that: The fixing assembly includes a fixing bolt (2-6), a thermal expansion washer (2-7), and a fixing nut (2-8). The thermal expansion washer (2-7) is sleeved on the outside of the fixing bolt (2-6) and located on the bolt head side. For the fixing assembly connecting the upper die (2-1) and the lower die (2-2), the fixing bolt (2-6) passes through the lower die (2-2) and the upper die (2-1) in sequence, and the fixing nut (2-8) is threaded to the end of the fixing bolt (2-6) that passes through the upper die (2-1). The fixing nut (2-8) is located on the side of the lower die (2-2) away from the upper die (2-1). For the fixing assembly connecting the left punch (2-3) and the upper die (2-1), the fixing bolt (2-6) passes through the left punch (2-3) and the upper die (2-1) in sequence, and the fixing nut (2-8) is threaded to the end of the fixing bolt (2-6) that passes through the upper die (2-1); For the fixing assembly connecting the left punch (2-3) and the lower die (2-2), the fixing bolt (2-6) passes through the left punch (2-3) and the lower die (2-2) in sequence, and the fixing nut (2-8) is threaded to the end of the fixing bolt (2-6) that passes through the lower die (2-2); For the fixing assembly connecting the right punch (2-4) and the upper die (2-1), the fixing bolt (2-6) passes through the right punch (2-4) and the upper die (2-1) in sequence, and the fixing nut (2-8) is threaded to the end of the fixing bolt (2-6) that passes through the upper die (2-1); For the fixing assembly connecting the right punch (2-4) and the lower die (2-2), the fixing bolt (2-6) passes through the right punch (2-4) and the lower die (2-2) in sequence, and the fixing nut (2-8) is threaded to the end of the fixing bolt (2-6) that passes through the lower die (2-2); The thermal expansion washer (2-7) expands axially during the thermoforming process to offset the axial expansion of the fixing bolt (2-6) when it is heated, so that the preload of the bolt remains unchanged during the thermoforming process. This controls the compressive stress of the die and punch on the arc-shaped thin-walled structure to remain constant, ensuring the consistency and stability of the mechanical properties of the arc-shaped thin-walled structure after forming, as well as the storage and release of its own elastic potential energy.

6. The precision forming mold for a spatial arc-shaped thin-walled structure according to claim 5, characterized in that: The blank for the thin-walled forming structure is a high-strength metal material.

7. A method for precision forming and manufacturing of a spatial arc-shaped thin-walled structure using a precision forming mold for a spatial arc-shaped thin-walled structure as described in any one of claims 1-6, characterized in that, include: Preparation of thin-walled shaped structural blanks; The thin-walled forming blank is positioned and installed between the upper die (2-1) and the lower die (2-2) using a positioning pin (2-5). Then, the upper die (2-1) and the lower die (2-2) are fixed together using a fixing assembly. After fixing, the distance between the planar areas of the upper die (2-1) and the lower die (2-2) is twice the thickness of the thin sheet blank. The left punch (2-3) and the right punch (2-4) are inserted between the upper die (2-1) and the lower die (2-2) and between the two thin sheet blanks. The left punch (2-3) and the right punch (2-4) are then fixed together with the upper die (2-1) and the lower die (2-2) using a fixing assembly to obtain the assembled part. The assembly is subjected to overall heat treatment.

8. The manufacturing method according to claim 7, characterized in that, The preparation of the thin-walled shaped structural blank includes: The microgroove structure (1-5) and positioning pin hole (1-6) on the two thin plate blanks are processed by femtosecond laser cutting; Two thin plate blanks with microgroove structures (1-5) and positioning pin holes (1-6) already processed are welded together using a pulsed laser to form a weld. The weld includes a central weld (1-3) and two separation welds (1-4). During welding, the laser spot is controlled to move along the direction of the weld while oscillating around both sides of the weld to obtain a weld with a width of 0.1-0.8 mm. The thickness of the separation welds (1-4) is greater than twice the thickness of the thin plate blank.

9. The manufacturing method according to claim 7, characterized in that, The heat treatment of the assembly as a whole includes: The assembly was placed inside the muffle furnace, and the furnace was evacuated, with the pressure controlled at 10. -1 -10 -7 Within Pa; Annealing, high-temperature thermoplastic molding and cooling are performed in sequence to restore the vacuum environment inside the muffle furnace to the atmospheric environment. The assembled parts are taken out and disassembled to obtain an arc-shaped thin-walled structure (1).

10. The manufacturing method according to claim 9, characterized in that: The annealing process includes setting the internal temperature of the muffle furnace to 550-600℃ and the annealing time to 1-1.5h. High-temperature thermoplastic molding includes, after reaching the annealing time, heating the muffle furnace temperature to 800-1000℃ for 10-15 minutes; Cooling involves gradually reducing the muffle furnace temperature to 250-450℃ over 0.5-1 hour, maintaining this temperature for 1.5-2 hours, then turning off the muffle furnace and allowing the assembled parts to cool naturally to room temperature.

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