Precise forming manufacturing die and method for space arc-shaped thin-wall structure

Abstract

A precise forming and manufacturing method for a spatial arc-shaped thin-wall structure relates to the field of precise forming of high-precision arc-shaped thin-wall structures, and comprises an upper female die, a lower female die, a left male die, a right male die and a positioning pin, the upper female die and the lower female die are consistent in structure and are symmetrical about an XOY plane, and the left male die and the right male die are consistent in structure and are symmetrical about a YOZ plane. A locating pin special hole is formed in the symmetric line of the upper female die and the lower female die, a thin-wall forming structure blank is installed between the upper female die and the lower female die, a locating pin penetrates through the locating pin special hole and a locating pin hole, and the upper female die and the lower female die are fixed through a fixing assembly. The inner arc surfaces of the upper female die and the lower female die are respectively designed according to upper and lower theoretical curved surfaces of the arc-shaped thin-wall structure; the left male die and the right male die are connected to the two sides of the upper female die through fixing assemblies, the left male die and the right male die are connected with the lower female die through fixing assemblies, and the die inner cambered surfaces of the left male die and the right male die are designed according to the left theoretical curved surface and the right theoretical curved surface of the arc-shaped thin-wall structure respectively. And high-precision manufacturing of the unit arc-shaped thin-wall structure is achieved.

Description

Technical Field

[0001] The present invention relates to the field of precision forming manufacturing of high-precision arc-shaped thin-wall structures, and in particular to a precision forming manufacturing mold and method for a novel arc-shaped thin-wall structure unit of a spatial high-precision self-expanding mechanism. Background Art

[0002] At present, space reconnaissance and surveillance means are restricted by the attenuation of electromagnetic waves in the atmosphere, radar multi-region coordination, and high-orbit width, which makes the time for early warning aircraft to stay in the air, the revisit time of low-orbit constellations, and the monitoring of the controlled area extremely limited, exacerbating the prominent problems of the current existing information perception means such as "not seeing clearly, not recognizing accurately, not seeing far, and not keeping an eye on". Since the aperture of the space optical remote sensor will directly determine the observation resolution, the future high-orbit reconnaissance satellite will develop towards a higher order of resolution, which will inevitably require the system equivalent aperture to reach a width of more than 100 meters. At the same time, future microwave reconnaissance satellites are developing in a new direction of ultra-large aperture and distributed array combination. Through payload arrays or formations, they can realize ultra-large virtual apertures of hundreds of meters, kilometer-level space ultra-long baseline interferometry, large-scale moving target detection and imaging, large-capacity communications and other reconnaissance functions, which also puts forward an urgent demand for ultra-large structural support platforms above 100 meters.

[0003] At present, the space extension mechanism is the most effective means to construct a large-scale functional support platform structure in orbit. Commonly used extension mechanisms are mainly divided into 6 types according to the structural form, including thin-walled tube type, sleeve type, coiled type, hinged type, inflatable extension type and tension integrated system type. However, due to the limited size of the internal space envelope of the launch vehicle, the maximum engineering extension size limit of the above commonly used deployment mechanisms is difficult to reach the order of 100 meters, which cannot meet the needs of large-scale space support platforms of 100 meters or even kilometers for large space facilities such as future medium and high orbit microwave reconnaissance, space solar power stations, and on-orbit service platforms. The new space high-precision self-deployment mechanism is a new configuration with lightweight, large storage ratio, passive drive and high environmental adaptability, and has good system scalability in space. It can not only meet the requirements of the launch vehicle envelope, but also can be combined with different structural requirements of spacecraft to carry out different configuration expansions to realize the construction of the entire structural platform, which can effectively solve the current problem of on-orbit construction of space support platforms above 100 meters.

[0004] The arc-shaped thin-walled structure involved in the present invention is the core functional execution unit module of the new spatial high-precision self-expanding mechanism. It is mainly composed of two Ω-shaped high-precision ultra-thin arc-shaped plates and shells connected back to back, and the whole is in an X shape to realize elastic potential energy storage. At the same time, many micro grooves parallel to each other and with the same width and length are designed at the connection position of the two Ω-shaped arc plates to form a grid structure to achieve elastic compressibility and deformation geometric coordination. When the arc-shaped thin-walled structural unit is compressed by an external force as a whole, it will have a smaller envelope size and present a buckling unstable elastic potential energy storage state. At the same time, the micro-groove configuration of the structural member presents geometric deformation. When the preload force in the folded state is released, the elastic potential energy is converted into kinetic energy, presenting an expanded state and maintaining a high stiffness. Since the new high-performance self-expanding structure is composed of multiple arc-shaped thin-walled structural units in parallel or in series, the shape and size errors and the mechanical properties of a single arc-shaped thin-walled structural unit generated during the manufacturing process will directly affect the comprehensive performance of the new spatial high-precision self-deployment mechanism such as the deployment directivity accuracy, deployment displacement accuracy, retention stiffness, and storage ratio through error accumulation. Therefore, higher requirements are put forward for the forming and manufacturing of single arc-shaped thin-walled structures. Summary of the invention

[0005] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and to provide a spatial arc-shaped thin-walled structure precision forming manufacturing mold and method to meet the high-precision manufacturing requirements of the arc-shaped thin-walled structure of the core functional execution unit in the above-mentioned new spatial high-precision self-expanding mechanism.

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

[0007] The technical solutions provided by this application are as follows:

[0008] A spatial arc-shaped thin-walled structure precision forming manufacturing mold is used to form a thin-walled forming structure blank to obtain an arc-shaped thin-walled structure. The thin-walled forming structure blank includes two thin plate blanks. The middle parts of the two thin plate blanks are fixed by a middle weld. The two thin plate blanks have separation welds on both sides of the middle weld. The surfaces of the two thin plate blanks have micro-groove structures and positioning pin holes. The length direction of the micro-groove structure is perpendicular to the length direction of the middle weld. The positioning pin hole is located at the middle weld position of the thin plate blank. The mold includes an upper concave mold, a lower concave mold, a left punch, a right punch and a positioning pin. The structures of the upper concave mold and the lower concave mold are consistent. The spatial relative installation positions of the two are symmetrical about the XOY plane (horizontal plane). The left punch and the right punch are symmetrical about the XOY plane (horizontal plane). The structures of the molds are consistent, and the relative installation positions of the two in space are symmetrical about the YOZ plane (vertical plane). There are multiple special holes for locating pins on the symmetry lines of the upper die and the lower die. The thin-walled forming structure blank is installed between the upper die and the lower die, and the locating pins pass through the special holes for locating pins and the locating pin holes. The upper die and the lower die are fixed by a fixing component, and the inner arc surfaces of the upper die and the lower die are designed according to the upper and lower theoretical surfaces of the arc-shaped thin-walled structure respectively; the left punch and the right punch are respectively connected to the two sides of the upper die through the fixing components, and the left punch and the right punch are connected to the lower die through the fixing components, and the inner arc surfaces of the left punch and the right punch are respectively designed according to the left and right theoretical surfaces of the arc-shaped thin-walled structure.

[0009] After the left and right punches are connected as a whole with the upper and lower dies through twelve sets of fixing components, their internal curved surface space just fits perfectly with 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 alloy, 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 away from the lower die, and the upper connecting structure is 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 away from the upper die, and the lower connecting structure is 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 assembly, and the upper curved surface structure and the lower curved surface structure are of equal thickness.

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

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

[0013] Preferably, a pulsed laser is used to weld two plane thin-walled plates that have been microgrooved. The welding position is 1.5-2.5 mm inside the arc surface separation line at both ends of the theoretical arc thin-walled structure and the symmetry line of the separation line at both ends of the plane thin-walled plate. The laser spot is controlled by adjusting the galvanometer to move along the weld direction of the plane thin-walled plate and swing around the two sides of the weld at a certain frequency. By adjusting the welding speed, laser power, swing frequency, swing radius, beam posture and other process parameters, a low-rigidity ultra-thin structure laser swing lap welding process window is established to obtain a 0.1-0.8 mm wide macro and micro-well formed welded joint, thereby achieving the purpose of suppressing weld defects and regulating the microstructure.

[0014] Preferably, a combined mold is used to maintain the shape of the spatial arc-shaped thin-walled structure. The curved surfaces at both ends of the upper die and the lower die are offset outwardly relative to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin plate blank. The curved surfaces on the left punch and the right punch are also offset outwardly relative to the left and right theoretical curved 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 the die are combined is exactly in fit with the upper, lower, left and right curved surfaces of the arc-shaped thin-walled structure, thereby achieving precise shape maintenance of the arc-shaped thin-walled structure.

[0015] Preferably, the arc-shaped thin-walled structure precision forming manufacturing mold is connected as a whole in the form of bolts and nuts, wherein the upper die and the lower die are connected by 4 pairs of bolts and nuts (fixed components), the left punch and the upper die are connected by 3 pairs of bolts and nuts (fixed components), the left punch and the lower die are connected by 3 pairs of bolts and nuts (fixed components), the right punch and the upper die are connected by 3 pairs of bolts and nuts (fixed components), and the right punch and the upper die are connected by 3 pairs of bolts and nuts (fixed components), for a total of 16 connection positions, the above bolts and nuts have the same specifications and can be used interchangeably, with the advantages of convenient disassembly and assembly, high connection reliability, etc. The thermal expansion washer expands when heated to offset the axial expansion and elongation of the fixing bolt when heated.

[0016] Preferably, the installation sequence of the punch, die and the flat thin plate blank after welding is controlled, and the deformation characteristics of the flat thin plate blank weld after stress are utilized. First, the upper and lower die and the flat thin plate blank after welding are positioned and installed by the locating pins, and 4 pairs of fixing bolts, thermal expansion washers and fixing nuts are installed in sequence. By setting the torque wrench threshold in advance, 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; because the average thickness of the weld area after high-speed swing laser welding is slightly larger than twice the wall thickness of the thin plate blank, the upper and lower side plane sheets at both ends of the flat thin plate blank will be warped and separated by 1-3mm after the weld in the upper and lower die plane areas is compressed, which is convenient for the insertion of the left and right punches, and finally 12 pairs of fixing bolts, expansion washers and fixing nuts for connecting and fixing the left and right punches and the upper and lower die are installed. The precision mold has a highly reliable and easy-to-disassemble connection design.

[0017] Preferably, the arc surface area of ​​the arc-shaped thin-walled structure is processed by an integrated thermoforming process method of an arc-shaped thin-walled structure and a conformal mold, and the conformal mold and the flat thin plate blank installed inside are first annealed together to eliminate the thermal stress inside the weld after continuous laser pulse welding and defects such as pores and cracks; after annealing, high-temperature thermoplastic forming is carried out together to achieve precision forming of the arc-shaped thin-walled structure; finally, low-temperature annealing is carried out together to eliminate the thermal stress inside the arc-shaped thin-walled structure material after thermoplastic forming, thereby improving the resilience of the arc-shaped thin-walled structure.

[0018] Preferably, the materials of the punch, die and locating pin are carbon fiber reinforced ceramic-based composite materials such as C / C composite materials, C / SiC composite materials, C / ZrC composite materials, etc., which have a low thermal expansion coefficient, high thermal conductivity coefficient, high temperature resistance and strong rigidity. The expansion of the punch and die surfaces along the normal direction during the hot forming process of the arc-shaped thin-walled structure is controlled to avoid a large compression force on the arc-shaped thin-walled structure inside the mold, thereby ensuring the wall thickness dimensional accuracy and shape accuracy of the arc-shaped thin-walled structure.

[0019] Preferably, R0.3-0.6 fillets are provided at the intersection of the arc surfaces symmetrical about the horizontal plane on both sides of the punch. On the one hand, this avoids the arc intersection being too sharp, preventing the punch from scratching the arc-shaped thin-walled structure during assembly. At the same time, the fillet that is 1-3mm lower than the warping separation distance of the upper and lower side plane thin plates helps the left and right punches to be smoothly inserted between the upper and lower side plane thin plates. On the other hand, the R0.3-0.6 size can ensure that a certain distance is maintained between the arc intersection and the weld at the separation point of the upper and lower thin-wall arc surfaces in the arc-shaped thin-walled structure, reserving an expansion gap during the hot forming process of the arc-shaped thin-walled structure, and avoiding the arc-shaped thin-walled structure from being squeezed by the punch after its own expansion, causing the weld to tear.

[0020] Preferably, the cross-section of the curved surface structure on both sides of the die is designed to be of equal thickness to ensure that during the integrated hot forming process of the arc-shaped thin-walled structure, the tiny expansion of the curved surface structure of the die due to heat is consistent along the normal direction of the curved surface, and the compressive stress of the die on each position of the arc-shaped thin-walled surface during the hot forming process is directly controlled to remain consistent in magnitude and direction, thereby ensuring the shape and position accuracy of the curved surface of the arc-shaped thin-walled structure after forming, and avoiding the problem of weld tearing caused by excessive deformation of the welds 1.5-2.5mm inside the separation line of the arc-shaped surfaces at both ends of the arc-shaped thin-walled structure.

[0021] Preferably, since the fixing bolts connecting the die and the punch will expand and elongate along the axial direction of the bolts during the hot forming process, the connection preload force of the fixing bolts on the die and the punch will be reduced, which will directly lead to uneven compressive stress of the die and the punch on the arc-shaped thin-walled structure during the hot forming process. On the one hand, the uniformity of the cross-sectional thickness of the arc-shaped thin-walled structure cannot be guaranteed. On the other hand, it will cause unevenness of the internal metal structure of the arc-shaped thin-walled structure after hot forming, which seriously affects the mechanical properties of the arc-shaped thin-walled structure and the consistency and stability of its storage and release of elastic potential energy during use. It is impossible to guarantee the comprehensive performance of the new high-performance self-stretching structure composed of multiple arc-shaped thin-walled structural units in parallel or in series, such as the deployment directional accuracy, deployment displacement accuracy, stiffness retention, and storage ratio. Therefore, an elastic gasket is designed and installed on the fixing bolt to ensure that the bolt maintains a certain preload during the hot forming process and controls the compressive stress of the die and the punch on the arc-shaped thin-walled structure to remain constant.

[0022] Preferably, since conventional mechanical elastic washers have thermal failure problems in long-term high-temperature environments, the elastic force released to the outside will gradually decrease with the increase of temperature and time, resulting in the inability of conventional mechanical elastic washers to ensure that the preload force of the fixing bolts remains constant during the thermoforming process of the arc-shaped thin-walled structure, and thus the compressive stress of the concave and convex dies on the arc-shaped thin-walled structure remains uniform and constant; therefore, according to the relationship between the expansion amount of the fixing bolts and the temperature change curve, a thermal expansion elastic washer is designed to replace the conventional mechanical elastic washer structure, and the washer material is selected from nickel-based alloys, molybdenum alloys, and chromium-based alloys. Alloys and other heat-resistant materials with certain rigidity, stable thermal expansion coefficient and wide linear expansion temperature range are made of special alloys. The inner ring diameter, outer ring diameter and thickness of the thermal expansion elastic gasket are reasonably planned and designed so that during the hot forming process, the expansion and elongation of the thermal expansion elastic gasket along the axial direction of the fixing bolt can offset the expansion and elongation of the fixing bolt along its own axial direction, ensuring that the preload force is always constant during the hot forming process of the bolt, controlling the compressive stress of the die and the punch on the arc-shaped thin-walled structure to remain constant, ensuring the mechanical properties of the arc-shaped thin-walled structure after forming and the consistency and stability of its own elastic potential energy storage and release.

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

[0024] 1. Provide a precision forming manufacturing mold structure of a highly elastic space arc-shaped thin-walled structure, which consists of an upper concave die, a lower concave die, a left punch, a right punch, a positioning pin, a fixing bolt, a fixing nut, and a thermal expansion washer; the arc surfaces at both ends of the upper and lower concave dies are designed according to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure, respectively, and are offset outwardly relative to the upper and lower theoretical curved surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin plate 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 outwardly relative to the left and right theoretical curved surfaces of the arc-shaped thin-walled structure by a distance equal to the wall thickness of the thin plate blank, which can realize high-precision shape control of the arc-shaped thin-walled structure, and is suitable for the forming of arc-shaped thin-walled structures of various high-strength metal materials such as titanium alloy and stainless steel; the mold is connected as a whole in the form of a bolt nut, and the bolts and nuts at various locations have the same specifications and can be used interchangeably, and have the advantages of convenient disassembly and assembly, high connection reliability, etc.

[0025] 2. Femtosecond laser cutting is used to process the micro-groove structure on the arc-shaped thin-walled structure. The micro-groove is processed on the rectangular flat thin-walled metal sheet by controlling the process parameters. The cold processing characteristics of femtosecond laser cutting can reduce the formation of the heat-affected zone, reduce the thermal stress and thermal damage of the base material, and inhibit the deformation of the flat thin plate blank.

[0026] 3. Pulsed laser is used to weld two flat thin-walled plates that have been processed with microgrooves. By adjusting the process parameters such as welding speed, laser power, oscillation frequency, oscillation radius, and beam posture, a low-rigidity ultra-thin structure laser oscillation lap welding process window is established to obtain a 0.1-0.8mm wide and well-formed welded joint, thereby achieving the purpose of suppressing weld defects and regulating the microstructure.

[0027] 4. According to the structural characteristics of the punch and the die, a method for using a precision forming manufacturing die is provided. The method utilizes the characteristic that the average thickness of the weld area after high-speed swing laser welding is slightly greater than twice the wall thickness of the thin plate blank. When the upper and lower dies are installed, the thin plate weld in the plane area of ​​the die will be warped and separated by 1-3 mm after being compressed. At the same time, it is convenient to insert the left and right punches, which is beneficial to the installation of the die and the thin plate blank.

[0028] 5. Provide a precision forming manufacturing process method for a highly elastic spatial arc-shaped thin-walled structure, perform a low-temperature annealing treatment together with the mold and the flat thin plate blank installed inside it, eliminate the thermal stress inside the weld after continuous laser pulse welding and defects such as pores and cracks, and perform high-temperature thermoplastic molding together after annealing to achieve precision forming of the arc-shaped thin-walled structure. Finally, perform a low-temperature annealing treatment together to eliminate the thermal stress inside the arc-shaped thin-walled structure material after thermoplastic molding, which 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. Use C / C composite materials, C / SiC composite materials, C / ZrC composite materials and other carbon fiber reinforced ceramic matrix composite materials with low thermal expansion coefficient, high thermal conductivity coefficient, high temperature resistance and strong rigidity as the manufacturing materials of punches, die and locating pins, reduce the expansion of the punch and die surfaces along the normal direction during the hot forming process of the arc-shaped thin-walled structure, avoid the mold inside the mold to produce a large compression force on the arc-shaped thin-walled structure, and ensure the wall thickness size accuracy and shape accuracy of the arc-shaped thin-walled structure.

[0030] 7. The arc surfaces on both sides of the punch are symmetrical about the horizontal plane and are designed with R0.3-0.6 fillets to avoid the arc surface intersection being too sharp, which can prevent the punch from scratching the arc-shaped thin-walled structure during assembly. At the same time, the fillet that is 1-3mm lower than the warping separation distance of the upper and lower flat thin plates helps the left and right punches to be smoothly inserted between the upper and lower flat thin plates; in addition, the R0.3-0.6mm fillet structure can ensure that the arc surface intersection is kept at a certain distance from the weld at the separation of the upper and lower thin-wall arc surfaces in the arc-shaped thin-walled structure, and reserve an expansion gap for the arc-shaped thin-walled structure during hot forming, which can avoid the arc-shaped thin-walled structure itself expanding and being squeezed by the punch and causing the weld to tear.

[0031] 8. The double-sided equal-thickness cross-section structure of the die can ensure that the small thermal expansion of the die surface structure during the hot forming process is consistent along the normal direction of the surface, and directly control the size and direction of the compressive stress of the die on the arc-shaped thin-walled surface at various positions during the hot forming process to ensure the shape and position accuracy of the arc-shaped thin-walled structure after forming, and avoid the weld tearing problem caused by excessive deformation of the weld 1.5-2.5mm inside the arc surface separation line at both ends of the arc-shaped thin-walled structure.

[0032] 9. A heat expansion elastic gasket specially used in hot forming occasions of the present invention is designed and installed at the end of the nail head of the fixing bolt. The gasket material is selected from heat-resistant special alloy materials such as nickel-based alloy, molybdenum alloy, chromium alloy, etc., which have a certain rigidity, stable thermal expansion coefficient, and a wide linear expansion temperature range. The principle of thermal expansion is utilized so that during the hot forming process, the expansion and elongation of the heat expansion elastic gasket along the axial direction of the fixing bolt can offset the expansion and elongation of the fixing bolt along its own axial direction, thereby ensuring that a constant preload is maintained during the hot forming process of the bolt, solving the problem of unstable bolt preload caused by thermal failure of conventional mechanical elastic gaskets in a long-term high-temperature environment, controlling the compressive stress of the arc-shaped thin-walled structure by the die and the punch to remain constant, ensuring the mechanical properties of the arc-shaped thin-walled structure after forming and the consistency and stability of its own elastic potential energy storage and release, thereby improving the comprehensive performance of the new high-performance self-stretching structure formed by parallel or interlaced combination of multiple arc-shaped thin-walled structural units, such as the deployment directivity accuracy, deployment displacement accuracy, rigidity retention, and storage ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1It is a schematic diagram of the arc-shaped thin-walled structure of the core functional execution unit in the new spatial high-precision self-deployment mechanism;

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

[0035] Figure 3 It is a schematic diagram of the decomposition of the mold installation form during the spatial arc thin-wall thermoforming process.

[0036] Description of the accompanying drawings: 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. Micro-groove structure; 1-6. Positioning pin hole;

[0037] 2. High-precision arc-shaped thin-wall structure manufacturing mold; 2-1. Upper concave die; 2-2. Lower concave die; 2-3. Left punch; 2-4. Right punch; 2-5. Locating pin; 2-6. Fixing bolt; 2-7. Thermal expansion washer; 2-8. Fixing nut. DETAILED DESCRIPTION

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

[0039] refer to Figure 1 The arc-shaped thin-walled structure 1, a core functional execution unit in the novel space high-precision self-deployment mechanism, is composed 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 through a middle weld 1-3 distributed on the axial symmetry line of the Ω-shaped arc-shaped thin plates and two arc-shaped structure separation welds 1-4 distributed 5-10 mm inside the arc-shaped surface separation line of the two Ω-shaped thin plates. The arc-shaped thin-walled structure 1 is X-shaped as a whole, which can realize elastic potential energy storage; in the plane area where the two Ω-shaped arc plates are in back-to-back contact, two rows of micro-groove matrices (micro-grooves) parallel to each other and having the same width and length are distributed. The length and width of the groove are designed according to the actual storage and release requirements of elastic potential energy), forming micro-groove structures 1-5, which can achieve elastic compressibility and deformation geometric coordination. When the arc-shaped thin-walled structure 1 is compressed by an external force as a whole, it will have a smaller envelope size and present an elastic potential energy storage state of buckling instability. At the same time, the micro-groove structure 1-5 configuration presents geometric deformation. When the preload force in the collapsed state is released, the elastic potential energy is converted into kinetic energy, presenting an expanded state and maintaining a high stiffness; the positioning pin holes 1-6 located on the axial symmetry line of the two Ω-shaped arc-shaped thin plates are process holes, which are used in combination with the positioning pins to constrain the arc-shaped thin-walled structure 1 in Figure 2 The spatial position inside the mold 2 for manufacturing the medium and high precision arc thin-wall structure.

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

[0041] refer to Figure 2 and Figure 3 The embodiment of the present application discloses a spatial arc-shaped thin-wall structure precision forming manufacturing mold 2, which is composed of an upper concave mold 2-1, a lower concave mold 2-2, a left punch 2-3, and a right punch 2-4. The upper die 2-1 and the lower die 2-2 have the same structure and are symmetrical about XOY (horizontal plane) as a whole. The inner arc surfaces of the molds at both ends of the upper and lower dies are designed according to the upper and lower theoretical surfaces of the arc-shaped thin-walled structure 1, respectively. At the same time, the cross-sections of the curved surface structures on both sides of the die are designed to be of equal thickness. During the hot forming process, the compressive stress of the die on each position of the arc-shaped thin-walled structure 1 is controlled to be consistent in magnitude and direction, thereby 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 structure separation welds at both ends of the arc-shaped thin-walled structure 1; there are four special holes for locating pins on the axial symmetry lines of the two dies, and the spatial position relationship between the upper and lower dies and the arc-shaped thin-walled structure 1 is ensured by the locating pins 2-5, and they are connected by 4 sets of fixing components, which include 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 YOZ (vertical plane) as a whole. The inner arc surfaces of the molds 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. The arc surfaces on both sides of the punch that are symmetrical about the horizontal plane are provided with R0.3-0.6 fillet structural features to prevent the punch from scratching the arc-shaped thin-walled structure during assembly, and at the same time ensure that a certain distance is maintained between the punch and the upper and lower thin-wall arc surfaces of the arc-shaped thin-walled structure 1, so as to provide the arc-shaped thin-walled structure 1 with a good fit. During the hot forming process, an expansion gap is reserved to prevent the arc-shaped thin-walled structure 1 from being squeezed by the punch and causing the weld to tear. When the left punch and the right punch are installed, they are connected to the upper die through three sets of fixing components, and when the left punch and the right punch are installed, they are connected to the lower die through three sets of fixing components, so that after the high-precision arc-shaped thin-walled structure manufacturing mold 2 is assembled, its internal curved surface space just fits with the upper, lower, left and right curved surfaces of the arc-shaped thin-walled structure 1, thereby achieving precise shape control of the arc-shaped thin-walled structure 1 during the hot forming process.

[0042] The high-precision arc-shaped thin-wall structure manufacturing mold 2 is suitable for molding materials including titanium alloy, stainless steel and other high-strength metal materials.

[0043] refer to Figure 3, a method for precision forming and manufacturing a space arc-shaped thin-walled structure of the present invention is described in detail in combination with a specific TA15 titanium alloy arc-shaped thin-walled structure precision forming and manufacturing embodiment. It should be noted that this process method is not only applicable to titanium alloy materials, but also to various high-strength metal materials such as aluminum alloy and stainless steel. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present invention.

[0044] (1) Femtosecond laser cutting is used to process the microgrooves 1-5 and the positioning pin holes 1-6 on the arc-shaped thin-walled structure 1 of TA15 titanium alloy. By controlling the process parameters such as the femtosecond laser pulse energy, pulse width, scanning speed, focal length and spot diameter, the relative position between the spot and the plane thin-walled plate is adjusted, and the microgrooves and positioning pin holes are processed on two TA15 titanium alloy plane thin-walled metal sheets with the same size in the thickness range of 0.1-1 mm. The cold processing characteristics of femtosecond laser cutting are used to reduce the formation of the heat-affected zone, reduce the thermal stress and thermal damage of the base material, and inhibit the deformation of the plane thin plate blank, so as to realize the cold processing of the microgrooves 1-5 and the positioning pin holes 1-6 of the TA15 titanium alloy arc-shaped thin-walled structure 1;

[0045] (2) Two TA15 titanium alloy flat thin-walled plates that have been processed with microgroove structures 1-5 and locating pin holes 1-6 are welded by pulse laser to form a middle weld 1-3 and two arc-shaped structure separation welds 1-4, and a TA15 titanium alloy thin-walled formed structural blank is obtained. The laser spot is controlled by adjusting the galvanometer to move along the weld direction of the flat thin-walled plate and oscillate around the two 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 posture, a low-rigidity ultra-thin structure laser oscillating lap welding process window is established to obtain a 0.1-0.8mm wide weld joint with good macro and microscopic formation, thereby suppressing weld defects and regulating the weld microstructure.

[0046] (3) First, the upper die 2-1, the lower die 2-2 and the welded TA15 titanium alloy thin-walled forming structure blank are positioned and installed by four positioning pins 2-5, and four sets of fixing bolts 2-6, thermal expansion washers 2-7 and fixing nuts 2-8 are installed in sequence. By setting the torque wrench threshold in advance, 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 2-6 are tightened; the stress deformation characteristics of the weld of the TA15 titanium alloy flat thin plate blank are utilized. The average thickness of the weld area after high-speed oscillating laser welding is slightly greater than twice the wall thickness of the thin plate blank, which causes the upper and lower flat plates at both ends of the flat thin plate blank to be warped and separated by 1-3mm after the weld in the plane area of ​​the upper and lower dies is compressed, making it easier to insert the left and right punches. Finally, 12 sets of fixing bolts 2-6, thermal expansion washers 2-7 and fixing nuts 2-8 for connecting and fixing the left and right punches and the upper and lower dies are installed, and tightening torque is applied to the fixing nuts 2-6 as required.

[0047] (4) The TA15 titanium alloy arc-shaped thin-walled structure 1 is processed by an integrated hot forming process. First, the high-precision arc-shaped thin-walled structure manufacturing mold 2 and the TA15 titanium alloy thin-walled forming structure blank installed therein are placed in a muffle furnace, and the muffle furnace is evacuated and the pressure is controlled at 10 -1 -10 -7Pa, to avoid the oxidation of the surface of the high-precision arc-shaped thin-walled structure manufacturing mold 2 and the TA15 titanium alloy sheet and the hydrogen embrittlement of the surface of the TA15 titanium alloy sheet caused by the O2, H2 and other components in the air during the subsequent hot forming process, to control the surface composition and organization of the formed TA15 titanium alloy arc-shaped thin-walled structure 1 to be consistent with the inside of the thin-walled structure, to ensure the mechanical properties of the TA15 titanium alloy arc-shaped thin-walled structure 1; then set the internal temperature of the muffle furnace to 550-600℃, anneal the TA15 titanium alloy sheet, and eliminate the continuous annealing. After the light pulse welding, the residual stress inside the weld and the defects such as pores and cracks are reduced, the mechanical properties and corrosion resistance of the weld area are improved, and the annealing time is controlled in the range of 1-1.5h; after the annealing time is reached, the temperature of the muffle furnace is set 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 accurately controlled in the range of 10-15min, so that the internal grain structure of the TA15 titanium alloy sheet is fully deformed and evenly distributed, while avoiding long-term high temperature of the grains. The temperature of the muffle furnace is then slowly lowered to 250-450°C, and the cooling process time is controlled within 0.5-1h to reduce the increase in the internal thermal stress accumulation of the TA15 titanium alloy sheet caused by the rapid change in temperature difference; finally, the temperature is maintained for 1.5-2h to eliminate the thermal stress inside the curved thin-walled structure material after thermoplastic forming in the form of low-temperature annealing, thereby improving the curvature of the curved thin-walled structure. Rebound performance; after completing the above hot forming process of TA15 titanium alloy arc-shaped thin-walled structure 1, close the muffle furnace, allow the high-precision arc-shaped thin-walled structure manufacturing mold 2 and the TA15 titanium alloy arc-shaped thin-walled structure 1 inside it to naturally cool to room temperature, restore the vacuum environment in the muffle furnace to the atmospheric environment, and then remove the 16 sets of fixing bolts, thermal expansion washers and fixing screws on the high-precision arc-shaped thin-walled structure manufacturing mold 2 in turn, take out the TA15 titanium alloy arc-shaped thin-walled structure 1 that has completed the hot forming process, and thus complete the full life cycle process of the arc-shaped thin-walled structure 1. It should be noted that the heat expansion washer 2-7 installed at the end of the nail head of the fixing bolt 2-6 is the key to ensure the successful hot forming of the TA15 titanium alloy arc-shaped thin-walled structure 1. By utilizing the principle of thermal expansion of the heat expansion washer 2-7, the expansion and elongation along the axial direction of the fixing bolt 2-6 can offset the expansion and elongation of the fixing bolt 2-6 along its own axial direction, thereby ensuring that the preload force is always constant during the hot forming process of the bolt, and can solve the problem of unstable bolt preload force caused by thermal failure of conventional mechanical elastic washers in long-term high-temperature environments, control the compressive stress of the arc-shaped thin-walled structure by the die and the punch to remain constant, thereby ensuring the mechanical properties of the TA15 titanium alloy arc-shaped thin-walled structure 1 after forming and the consistency and stability of its own elastic potential energy storage and release.

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

[0049] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A spatial arc-shaped thin-wall structure precision forming mold, characterized by: The invention is used for forming a thin-walled forming structure blank to obtain an arc-shaped thin-walled structure (1), wherein the thin-walled forming structure blank comprises two thin plate blanks, the middle parts of the two thin plate blanks are fixed by a middle weld (1-3), the two thin plate blanks have separation welds (1-4) on both sides of the middle weld (1-3), the surfaces of the two thin plate blanks have micro-groove structures (1-5) and positioning pin holes (1-6), the length direction of the micro-groove structures (1-5) is perpendicular to the middle weld (1-3) ), the positioning pin hole (1-6) is located at the middle weld (1-3) of the thin plate blank, the mold comprises an upper concave mold (2-1), a lower concave mold (2-2), a left punch (2-3), a right punch (2-4) and a positioning pin (2-5), the upper concave mold (2-1) and the lower concave mold (2-2) have the same structure, the relative installation positions of the two in space are symmetrical about the XOY plane, the left punch (2-3) and the right punch (2-4) have the same structure, and the two The relative installation position in space is symmetrical about the YOZ plane. There are a plurality of special holes for positioning pins on the symmetry lines of the upper die (2-1) and the lower die (2-2). The thin-walled forming structure blank is installed between the upper die (2-1) and the lower die (2-2). The positioning pins (2-5) pass through the special holes for positioning pins and the positioning pin holes (1-6). The upper die (2-1) and the lower die (2-2) are fixed by a fixing assembly. The upper die (2-1) and the lower die (2-2) are fixed by a fixing assembly. -2) are designed according to the upper and lower theoretical 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 fixed components, and the left punch (2-3) and the right punch (2-4) are connected to the lower die (2-2) through fixed components, and 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 surfaces of the arc-shaped thin-walled structure.

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

3. A spatial arc-shaped thin-wall structure precision forming mold according to claim 1, characterized in that: The left punch (2-3) comprises a left mounting plate and a left forming structure, the left mounting plate being connected to the side of the left forming structure away from the thin-walled forming structure blank, and the left mounting plate is connected to the side of the upper die (2-1) and the lower die (2-2) away from the right punch (2-4) through a fixing assembly; the right punch (2-4) comprises a right mounting plate and a right forming structure, the right mounting plate being connected to the side of the right forming structure away from the thin-walled forming structure blank, and the right mounting plate is connected to the side of the upper die (2-1) and the lower die (2-2) away from the left punch (2-3) through a fixing assembly.

4. A spatial arc-shaped thin-wall structure precision forming mold according to claim 3, characterized in that: The left forming structure and the right forming structure both have an upper arc surface and a lower arc surface, the upper arc surface and the lower arc surface are symmetrical about the contact surface of the two thin plate blanks, the contact surface is an XOY surface, and a R0.3-0.6 fillet structure is arranged at the intersection of the upper arc surface and the lower arc surface.

5. The spatial arc-shaped thin-wall structure precision forming mold according to claim 1, characterized in that: The fixing assembly comprises a fixing bolt (2-6), a heat expansion washer (2-7) and a fixing nut (2-8); the heat expansion washer (2-7) is sleeved outside the fixing bolt (2-6) and is located on the bolt head side; For the fixing assembly connected between 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, the fixing nut (2-8) is threadedly connected to the end of the fixing bolt (2-6) passing through the upper die (2-1), and the fixing nut (2-8) is located on the side of the lower die (2-2) facing away from the upper die (2-1); For the fixing assembly connected between 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 threadedly connected to the end of the fixing bolt (2-6) passing through the upper die (2-1); For the fixing assembly connected between 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 threadedly connected to the end of the fixing bolt (2-6) passing through the lower die (2-2); For the fixing assembly connected between 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 threadedly connected to the end of the fixing bolt (2-6) passing through the upper die (2-1); For the fixing assembly connected between 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 threadedly connected to the end of the fixing bolt (2-6) passing through the lower die (2-2); The heat expansion washer (2-7) expands axially when heated during the hot forming process to offset the axial expansion and elongation of the fixing bolt (2-6) when heated, so that the pre-tightening force of the bolt remains unchanged during the hot forming process, and the compressive stress of the concave and convex dies on the arc-shaped thin-walled structure is controlled to remain constant, thereby ensuring the mechanical properties of the arc-shaped thin-walled structure after forming and the consistency and stability of its own elastic potential energy storage and release.

6. A spatial arc-shaped thin-wall structure precision forming mold according to claim 5, characterized in that: The thin-wall forming structure blank is made of high-strength metal material.

7. A method for manufacturing a space arc thin-wall structure precision forming using a space arc thin-wall structure precision forming mold according to any one of claims 1 to 6, characterized in that: include: Preparation of thin-walled formed structure blanks; The thin-walled forming structure blank is positioned and installed between the upper die (2-1) and the lower die (2-2) by means of positioning pins (2-5), and then the upper die (2-1) and the lower die (2-2) are fixed by means of a fixing assembly, and after fixing, the distance between the plane areas of the upper die (2-1) and the lower die (2-2) is twice the thickness of the thin plate 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 plate blanks, and the left punch (2-3) and the right punch (2-4) are fixed between the upper die (2-1) and the lower die (2-2) by means of a fixing assembly, and an assembly is obtained; The entire assembly is heat treated.

8. The manufacturing method according to claim 7, characterized in that: The method of preparing a thin-walled formed structure blank comprises: Femtosecond laser cutting is used to process micro-groove structures (1-5) and positioning pin holes (1-6) on two thin plate blanks; A pulsed laser is used to weld two thin plate blanks on which microgroove structures (1-5) and positioning pin holes (1-6) have been processed to form a weld, wherein the weld includes a middle 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 swinging around the two sides of the weld to obtain a weld with a width of 0.1-0.8 mm. The thickness of the separation weld (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 entire assembly comprises: Place the assembly in a muffle furnace and evacuate the muffle furnace to a pressure of 10 -1 -10 -7 Within Pa; Annealing treatment, high-temperature thermoplastic molding and cooling are performed in sequence, the vacuum environment in the muffle furnace is restored to the atmospheric environment, and the assembly is 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 treatment includes setting the internal temperature of the muffle furnace to 550-600° C. and the annealing time to 1-1.5 hours; High temperature thermoplastic forming includes, after reaching the annealing time, the temperature of the muffle furnace is raised to 800-1000℃ for 10-15min; The cooling process includes gradually reducing the temperature of the muffle furnace to 250-450°C over a period of 0.5-1h, and finally maintaining the temperature for 1.5-2h, closing the muffle furnace, and allowing the assembly to cool naturally to room temperature.

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