Method and apparatus for forming a compartment section with internal bosses

Abstract

This invention provides a method and apparatus for forming a compartment section with internal bosses, belonging to the field of metal plastic processing technology. The forming method includes the following steps: preparing a compartment section substrate; forming multiple internal bosses on the inner wall surface of the prepared compartment section substrate using arc wire additive manufacturing; and radially extruding each of the internal bosses from the inside to the outside along the radial direction of the compartment section substrate at a first preset forming temperature to form a compartment section with the internal bosses. This invention uses arc wire additive manufacturing to additively form multiple internal bosses at designated locations on the inner wall surface of the compartment section substrate. Then, radial hot extrusion is applied to each internal boss to improve the metallurgical bonding quality of the substrate-additive interface, eliminate uneven solidification structure and voids in the additive region, and compared with traditional riveting or welding processes for internal bosses, avoids the problem of decreased load-bearing performance caused by the introduction of weak connection areas and stress concentration.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing technology, specifically relating to a forming method and forming device for a compartment section with an internal boss. Background Technology

[0002] As a key load-bearing structural component of a missile, the missile hull is characterized by complex load environments, high specific strength requirements, and high structural efficiency requirements. Therefore, it is generally manufactured using high-strength aluminum alloy materials. Currently, most rocket hulls are custom-made, resulting in low structural versatility and poor process interchangeability, making it difficult to meet the needs of modern combat readiness. Therefore, manufacturing a basic aluminum alloy hull first, and then customizing local functions through internal bosses, has become an effective way to overcome the bottlenecks of low structural versatility and poor process interchangeability.

[0003] Currently, internal bosses in the cabin are mainly manufactured through mechanical riveting or fusion welding. However, these methods introduce microstructural abrupt changes, residual stress concentration, and weak mechanical properties in the joint area, restricting the load-bearing reliability and service safety of the cabin. Wire arc welding (WAAM) additive manufacturing has advantages such as high deposition efficiency, low cost, applicability to large-size components, and a wide range of material applications, making it an effective path for flexible forming of complex internal bosses. However, when additively manufacturing bosses on a substrate cabin, metallurgical defects are prone to exist at the substrate-additive interface. Furthermore, the additive bosses often contain uneven solidification structures and porosity, all of which contribute to the difficulty in meeting design requirements for the load-bearing capacity of the bosses. Summary of the Invention

[0004] Therefore, the present invention provides a method and apparatus for forming a compartment section with an internal boss, which can overcome the problems in the related art where metallurgical defects are easily present at the substrate-additive interface after the internal boss is formed, and the boss contains uneven solidification structure and pores, which together lead to the insufficient load-bearing performance of the boss to meet the design requirements.

[0005] To address the aforementioned problems, the present invention provides a method for forming a compartment section with an internal boss, comprising the following steps:

[0006] Preparation of the module substrate;

[0007] Multiple internal bosses are formed on the inner wall of the prepared compartment substrate using an electric arc wire additive manufacturing method.

[0008] At a first preset forming temperature, the internal bosses of each compartment are radially extruded from the inside to the outside along the radial direction of the compartment base to form a compartment having the internal bosses.

[0009] In some embodiments, at the first preset forming temperature, the rheological stress of the material of the boss inside the cabin is greater than the rheological stress of the material of the cabin segment substrate.

[0010] In some embodiments, the material of the boss inside the cabin is 5356 aluminum alloy, the material of the cabin segment base is 7055 aluminum alloy, the first preset forming temperature is 400℃±30℃, and the radial extrusion speed for the boss inside the cabin is 0.1mm / s -1mm / s.

[0011] In some embodiments, the module substrate is prepared by the following steps:

[0012] Upsetting matrix bar stock;

[0013] The upset matrix bar is reverse extruded to form a cylinder with a bottom wall;

[0014] The bottom wall of the cylinder is removed to form the compartment base.

[0015] In some embodiments, upsetting and back-extrusion of the matrix bar are performed at a second preset forming temperature, and the second preset forming temperature is higher than the first preset forming temperature; and / or, the material of the compartment matrix is ​​7055 aluminum alloy, and the extrusion speed of upsetting and back-extrusion of the matrix bar is 0.5mm / s-1.5mm / s.

[0016] In some embodiments, the protrusions inside the cabin are made of 5356 aluminum alloy, and the arc-fused wire additive manufacturing is carried out using the following process parameters:

[0017] The wire feed speed is 8 mm / s, the welding speed is 20 mm / s, the welding voltage is 20 V, and the welding current is 130 A; and / or, after depositing additive material to the target height on the boss in each of the compartments, a transition fillet is added at the junction of the boss in each compartment and the inner wall surface of the compartment substrate.

[0018] The present invention also provides a forming apparatus for performing the above-described forming method for a compartment section having internal bosses, comprising a radial extrusion die, the radial extrusion die comprising a radial extrusion die, a radial extrusion punch, and a radial displacement drive, the radial extrusion die comprising a first forming cavity, the radial extrusion punch comprising a plurality of radial extrusion petals arranged in a circumferential manner, the number of the radial extrusion petals being equal to the number of internal bosses, wherein when the radial extrusion die is in use, each of the radial extrusion petals corresponds one-to-one with each of the internal bosses, and the radial displacement drive can be driven to rise and fall to drive each of the radial extrusion petals to extrude each internal boss of the compartment from the inside out along the radial direction of the first forming cavity.

[0019] In some embodiments, the bottom wall of the first forming cavity is slidably connected to the bottom end of each of the radial extrusion valves; and / or, each of the radial extrusion valves includes a valve body and an outer boss on the outer circular wall surface of the valve body, the outer boss being detachably connected to the valve body, and the radial force-applying surface of the outer boss matching the shape of the force-bearing surface of the inner boss of the chamber.

[0020] In some embodiments, the bottom wall of the first forming cavity is provided with a groove extending radially from the inside to the outside, each groove having a top constriction in its cross-section, each extrusion flap having a limiting post at its bottom end, and each limiting post having a limiting portion at its bottom end that slides and limits the groove.

[0021] In some embodiments, the radial displacement drive is a regular N-shaped pyramid with a cross-section, where N is the number of radial extrusion petals and N≥3. The side of each radial extrusion petal away from the boss inside the cabin is an inclined surface that gradually moves away from the corresponding side of the boss inside the cabin from top to bottom. The inclined surface of each radial extrusion petal is respectively fitted and matched with each side surface of the regular N-shaped pyramid.

[0022] The forming method and forming apparatus for a compartment section with an internal boss provided by the present invention have the following beneficial effects:

[0023] Multiple internal bosses are additively formed at designated locations on the inner wall of the compartment substrate using arc wire additive manufacturing. Then, radial hot extrusion is applied to each internal boss to improve the metallurgical bonding quality of the substrate (i.e., compartment substrate)-additive (i.e., internal boss) interface (i.e., overcome metallurgical defects), eliminate uneven solidification structure and voids in the additive area. Compared with traditional riveting or welding internal boss processes, this not only avoids the problem of reduced load-bearing performance caused by the introduction of weak connection areas and stress concentration, but also, relying on the digital flexibility of the arc wire additive manufacturing process, the size, position and morphology of the internal bosses can be easily adjusted to meet the differentiated internal structure requirements of various types of compartments. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the steps of the method for forming a compartment section with an internal boss in an embodiment of the present invention.

[0026] Figure 2This is a schematic diagram of the forming process of a forming method for a compartment section with an internal boss in an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram (cross-sectional view) of the state of the upsetting reverse extrusion die in the forming device of the compartment section with the internal boss in the embodiment of the present invention during the upsetting process.

[0028] Figure 4 yes Figure 3 A top view of the flat-bottomed conical punch;

[0029] Figure 5 yes Figure 3 A top view of the upsetting reverse extrusion die;

[0030] Figure 6 This is a schematic diagram (cross-sectional view) of the state of the upsetting reverse extrusion die in the forming device of the compartment section with the internal boss in the embodiment of the present invention during the reverse extrusion process.

[0031] Figure 7 This is a schematic diagram of the state during the process of forming the internal boss of the compartment substrate by means of electric arc wire additive manufacturing on the inner wall of the compartment substrate in this invention.

[0032] Figure 8 This is a schematic diagram (cross-sectional view) of the radial extrusion die in the forming device for a compartment section with an internal boss in an embodiment of the present invention.

[0033] Figure 9 yes Figure 8 A cross-sectional view of the radial extrusion punch in the process;

[0034] Figure 10 yes Figure 9 Top view;

[0035] Figure 11 yes Figure 8 A top view of the radial extrusion die in the middle;

[0036] Figure 12 In this invention, the additive 5356 aluminum alloy and the base material 7055 aluminum alloy are processed in 0.1s. -1 True stress-strain curves at strain rates (when the first preset forming temperature is 400℃), where (a) corresponds to a radial extrusion speed of 1 mm / s and (b) corresponds to a radial extrusion speed of 0.1 mm / s;

[0037] Figure 13 In this invention, the additive 5356 aluminum alloy (i.e., the boss inside the cabin) and the base material 7055 aluminum alloy (i.e., the cabin section substrate) are processed in 0.1 seconds. -1Comparison of electron backscatter diffraction (EBSD) images before and after hot extrusion (compression) at the strain rate, where (a) is the microstructure before hot extrusion and (b) is the microstructure after hot extrusion (when the first preset forming temperature is 400℃).

[0038] The attached figures are labeled as follows:

[0039] 1. Radial extrusion die; 11. Radial extrusion die; 111. First forming cavity; 1111. Slide groove; 12. Radial extrusion punch; 121. Outer boss; 122. Limiting post; 1221. Limiting part; 13. Radial displacement drive; 141. First upper template; 142. First lower template; 2. Upsetting reverse extrusion die; 21. Upsetting reverse extrusion die; 22. Flat bottom conical punch; 23. Pressure plate; 24. Baffle plate; 241. Connecting rod; 251. Second upper template; 252. Second lower template; 261. Top plate; 262. Push rod; 31. Fixture; 32. Welding torch nozzle; 100. Cabin section base; 101. Cabin internal boss; 200. Base bar stock; 201. Cylinder. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0042] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0043] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0044] See also Figures 1 to 13 As shown, according to an embodiment of the present invention, a method for forming a compartment section having an internal boss is provided, comprising the following steps:

[0045] Prepare the module substrate 100;

[0046] Multiple internal protrusions 101 are formed on the inner wall of the prepared compartment base 100 by arc wire additive manufacturing. In a specific embodiment, four internal protrusions 101 are evenly spaced along the circumferential direction on the inner wall of the compartment base 100. The number, spacing and specific dimensions (e.g., length, width and height) of the aforementioned internal protrusions 101 can be reasonably selected according to the actual working conditions.

[0047] At a first preset forming temperature, each of the internal bosses 101 of the compartment is radially extruded from the inside to the outside along the radial direction of the compartment base 100 to form a compartment having the internal bosses 101. Preferably, after radially extruding each internal boss 101 of the compartment and cooling to room temperature, the compartment with the internal bosses 101 is machined to remove flash, so that the compartment size matches the design size.

[0048] In this technical solution, multiple internal bosses 101 are formed at designated locations on the inner wall of the compartment substrate 100 using arc wire additive manufacturing. Then, radial hot extrusion is applied to each internal boss 101 to improve the metallurgical bonding quality of the substrate (i.e., compartment substrate 100) - additive manufacturing (i.e., internal boss 101) interface (i.e., overcome metallurgical defects), eliminate uneven solidification structure and voids in the additive manufacturing area. Compared with the traditional riveting or welding internal boss process, this not only avoids the problem of reduced load-bearing performance caused by the introduction of weak connection areas and stress concentration, but also, relying on the digital flexibility of the arc wire additive manufacturing process, the size, position and morphology of the internal bosses can be easily adjusted to meet the differentiated internal structure requirements of various types of compartments.

[0049] In some embodiments, at the first preset forming temperature, the rheological stress of the material of the boss 101 inside the compartment is greater than that of the material of the compartment substrate 100. That is, at the first preset forming temperature, the hardness of the boss 101 inside the compartment should be greater than that of the compartment substrate 100. This ensures that when radial extrusion force is applied to each boss 101 inside the compartment, the additive part can be smoothly pressed into the substrate, and in this process, the additive part itself undergoes significant plastic deformation. This achieves the core objective of strengthening the additive body itself through grain refinement, achieving densification by welding internal pores through material flow, and forming a strong metallurgical bonding interface with the substrate through coordinated deformation, thereby improving the overall performance and reliability of the structure.

[0050] In some embodiments, the protrusion 101 inside the cabin is made of 5356 aluminum alloy, and the cabin base 100 is made of 7055 aluminum alloy. The first preset forming temperature is 400℃±30℃, and the radial extrusion speed for the protrusion 101 inside the cabin is 0.1mm / s - 1mm / s. See details... Figure 12 As shown, it can be clearly seen that at radial extrusion speeds of 1 mm / s (12a) and 0.1 mm / s ( Figure 12 b) When the first preset forming temperature is 400°C, the 5356 aluminum alloy exhibits higher rheological stress and hardness than the 7055 aluminum alloy, which is beneficial to the effective elimination of metallurgical defects at the substrate-additive bonding interface and defects in the additive region in this invention.

[0051] It should be noted that the compartment substrate 100 in this invention is made of 7055 aluminum alloy, which is an ultra-high strength aluminum alloy with extremely high specific strength and stiffness, and can meet the core requirements of the compartment as the main load-bearing structure for load-bearing capacity and lightweight. The internal boss 101 of the compartment is made of 5356 aluminum alloy, which is an Al-Mg alloy with excellent plasticity, corrosion resistance and welding / additive manufacturing performance. This ensures that when the internal boss is additively manufactured on the compartment, good formability, low crack sensitivity and a more reliable metallurgical bonding interface with the 7055 substrate can be obtained.

[0052] In some embodiments, the compartment substrate 100 is prepared using an upsetting reverse extrusion die 2 according to the following steps:

[0053] Upsetting the base bar 200, specifically, the base bar 200 is placed in the upsetting reverse extrusion die 21 and a pressure plate 23 is placed on the top surface of the base bar 200. Then, the flat-bottomed conical punch 22 is controlled to press the base bar 200 downward, thereby achieving the upsetting purpose of the base bar 200.

[0054] Then, the aforementioned pressure plate 23 is removed from the top surface of the upset base bar 200, and the aforementioned flat-bottomed conical punch 22 is used to press the base bar 200 downward again. Under the constraint of the upset reverse extrusion die 21, the upset base bar 200 will be reverse extruded to form a cylinder 201 with a bottom wall.

[0055] The bottom wall of the cylinder 201 is then cut off (e.g., sawed) to form the compartment base 100.

[0056] In this technical solution, the cylindrical body 201 with a bottom wall is formed by upsetting and reverse extrusion, which can significantly improve the microstructure integrity, load-bearing efficiency, and bonding quality of the subsequent additive manufacturing interface. Specifically, the cylindrical body 201 in this invention objectively achieves microstructure optimization and performance foundation simultaneously through one-time forming: microstructure-wise, it directly obtains a high-quality forged microstructure with fine grains and continuous streamlines along the cylindrical shape, eliminating the streamline interruption and weak connection areas caused by split manufacturing; mechanically, based on this uniform and dense matrix, the overall strength, toughness, and fatigue resistance of the cylindrical body are fundamentally improved, and an ideal foundation is provided for achieving high-performance interface metallurgical bonding in subsequent additive manufacturing and hot extrusion processes.

[0057] In some embodiments, upsetting and reverse extrusion of the matrix bar 200 are performed at a second preset forming temperature, and the second preset forming temperature is higher than the first preset forming temperature. In a specific embodiment, when the material of the compartment matrix 100 is 7055 aluminum alloy, the second preset forming temperature is 470°C.

[0058] In this technical solution, the second preset forming temperature, i.e. the forming temperature of the upsetting reverse extrusion for the substrate, is higher than the first preset forming temperature, i.e. the forming temperature of the radial hot extrusion for additive manufacturing, to form a temperature gradient. This temperature gradient design follows the basic principles of hot deformation and microstructure evolution of high-strength aluminum alloys. Specifically, the upsetting reverse extrusion is carried out at 470°C, which aims to take advantage of the material's characteristic that the flow stress is significantly reduced at higher temperatures to achieve large plastic strain integral forming while avoiding cracking. The subsequent radial extrusion is reduced to 400°C, which is to effectively suppress excessive grain growth while ensuring that the interfacial atomic diffusion and dynamic recrystallization are fully carried out to eliminate defects and achieve metallurgical bonding. This synergistically optimizes the interfacial bonding quality and the overall mechanical properties of the component. This design reflects the synergistic concept of "forming-property integration" process chain.

[0059] In addition, it is worth emphasizing that the composite process of preparing cylindrical base sections by upsetting and reverse extrusion, flexible manufacturing of inner bosses by electric arc wire additive manufacturing, and radial hot extrusion to strengthen the interface has achieved integrated forming of complex-shaped inner boss sections, effectively improving the load-bearing performance of the final formed sections.

[0060] See details Figure 13 As shown, Figure 13 Image a shows the electron backscatter diffraction (EBSD) image of the initial interface between the additive 5356 aluminum alloy and the substrate 7055 aluminum alloy. It can be seen that the interface region contains Al-Mg phase enrichment and porosity defects. Furthermore, the interface clearly separates the plate-like structure of the substrate from the solidified structure of the additive, resulting in poor interfacial bonding performance. Figure 13 b is an EBSD image of the same interface position after radial extrusion hot deformation. It can be seen that the radial extrusion hot deformation treatment eliminates the microstructure separation phenomenon of the initial interface and forms a three-level continuous heterogeneous microstructure. At the same time, radial extrusion hot deformation effectively closes the pores in the additive region and transforms the solidified microstructure into a uniform deformed microstructure.

[0061] In some embodiments, the substrate 100 is made of 7055 aluminum alloy, and the upsetting and reverse extrusion speed of the substrate bar 200 is 0.5 mm / s-1.5 mm / s. This prevents excessively high upsetting / reverse extrusion speeds, which could lead to concentrated deformation heat, rapid material temperature rise, coarse grains, and incomplete dynamic recrystallization. Simultaneously, excessively rapid material flow may cause uneven filling, surface cracking or folding, and affect the bonding quality of subsequent additive manufacturing interfaces. Insufficiently high speeds result in excessively long forging times, causing the billet and die temperatures to fall below the forming temperature. In some preferred embodiments, the outer wall of the upsetting and reverse extrusion die 21 can be wrapped with insulating cloth.

[0062] In some embodiments, the material of the boss 101 inside the chamber is 5356 aluminum alloy. The arc welding wire additive manufacturing adopts the following process parameters: wire feed speed of 8 mm / s, welding speed of 20 mm / s, welding voltage of 20 V, and welding current of 130 A. This can match the heat input, forming speed (i.e. welding blank) with the material feed, ensure arc stability and better molten pool fluidity, thereby eliminating welding defects such as arc spatter and lack of fusion, and improving the surface forming quality and internal density of the boss 101 inside the chamber.

[0063] In some embodiments, after the boss 101 in each compartment is deposited with additive material to the target height (the target height is specifically determined according to actual needs), a transition fillet is added at the junction of the boss 101 in each compartment and the inner wall surface of the compartment substrate 100.

[0064] In this technical solution, a transition fillet is formed at the junction of the boss 101 inside the compartment and the compartment base 100 by additive manufacturing. This can reconstruct the right-angle edge connection structure into a smooth transition curved surface connection, thereby optimizing the geometric continuity at this point, significantly reducing stress concentration caused by geometric abrupt changes, and fundamentally improving fatigue life and load-bearing reliability. At the same time, it is worth emphasizing that this transition fillet (i.e., the chamfer structure) is not only more conducive to the stability of the molten pool and layer-by-layer deposition, reducing process defects, but the extra material reserved therein can also effectively compensate for the volume deficiency in the transition zone that may occur due to the difficulty of metal flow during the subsequent radial extrusion process, thereby ensuring that this critical area can achieve a full and dense metallurgical bond after plastic deformation.

[0065] In one specific embodiment, the radius of the aforementioned rounded corner structure is 20mm (R20), which can effectively reduce stress concentration and improve fatigue strength; its gentle curvature provides an ideal melt channel spreading path for WAAM, which is conducive to reducing internal defects; at the same time, it reserves sufficient compensation material for radial extrusion, ensuring that the transition zone is full and dense, thereby fully guaranteeing the reliability of the bond.

[0066] In some embodiments, before placing the base bar 200 into the upsetting reverse extrusion die 21, an oil-based lubricant is applied along the outer surface of the base bar 200, the top surface of the top plate 261 inside the upsetting reverse extrusion die 21, and the inner wall surface of the upsetting reverse extrusion die 21 to improve the smoothness of extrusion deformation.

[0067] It is understandable that before upsetting and radial extrusion of the boss 101 in the chamber, the corresponding mold components need to be heated to the corresponding preset forming temperature (such as the first preset forming temperature and the second preset forming temperature mentioned above) and kept warm.

[0068] According to an embodiment of the present invention, a forming apparatus for performing the above-described forming method for a compartment section having an internal boss is also provided, comprising a radial extrusion die 1, wherein the radial extrusion die 1 is specifically used for radial extrusion of the internal boss 101 within the aforementioned compartment section base 100, as detailed in the attached diagram. Figures 8 to 11 As shown, the radial extrusion die 1 includes a radial extrusion die 11, a radial extrusion punch 12, and a radial displacement drive 13. The radial extrusion die 11 includes a first forming cavity 111. It is understood that the shape and size of the inner annular cavity wall of the aforementioned first forming cavity 111 should be consistent with the shape and size of the outer cylinder wall of the compartment. The radial extrusion punch 12 includes a plurality of radial extrusion petals (not labeled in the figure) arranged in a ring, and the number of radial extrusion petals is equal to the number of protrusions 101 in the compartment. In the illustrated embodiment, the number of protrusions 101 in the compartment and the number of radial extrusion petals are both four. When the radial extrusion die 1 is used, each radial extrusion petal corresponds one-to-one with each protrusion 101 in the compartment. The radial displacement drive 13 can be driven to rise and fall to drive each radial extrusion petal to extrude each protrusion 101 in the compartment from the inside to the outside along the radial direction of the first forming cavity 111, thereby causing each protrusion 101 in the compartment to move toward the compartment base 100 and deform.

[0069] In this technical solution, the radial displacement drive 13 is used to achieve the synchronous outward sliding of each radial extrusion petal, thereby achieving the radial extrusion of the protrusion 101 in each chamber. The structure is simple and the operation is convenient.

[0070] In some embodiments, the bottom wall of the first forming cavity 111 is slidably connected to the bottom end of each of the radial extrusion flaps. It is understood that the sliding direction of the aforementioned slidable connection is the diameter direction of the first forming cavity 111.

[0071] In this technical solution, by slidingly connecting each radial extrusion flap with the bottom wall of the first forming cavity 111, the sliding of each radial extrusion flap can be guided, ensuring the smooth sliding of each radial extrusion flap, thereby ensuring the effective radial extrusion of each radial extrusion flap on the protrusion 101 in each chamber.

[0072] In some embodiments, each of the radial extrusion valves includes a valve body and an outer boss 121 located on the outer circular wall surface of the valve body (not indicated in the figure). The outer boss 121 is detachably connected to the valve body, and the radial force-applying surface of the outer boss 121 matches the shape of the force-bearing surface of the inner boss 101 of the chamber. It is understood that the area of ​​each of the aforementioned radial force-applying surfaces should be larger than the area of ​​the corresponding force-bearing surface of each inner boss 101 of the chamber, so as to ensure that the force-bearing surface of each inner boss 101 of the chamber is radially supported by the corresponding radial force-applying surface during the entire radial extrusion deformation process.

[0073] In this technical solution, each external protrusion 121 is detachably assembled onto the outer circular wall of each petal body. The external protrusion 121 with a more suitable hardness can be selected according to the specific material of the aforementioned compartment base 100, making the radial extrusion of the internal protrusion 101 more reliable, ensuring that the internal protrusion 101 is fully deformed after being extruded, thereby improving the quality of the metallurgical interface between the internal protrusion 101 and the compartment base 100 and optimizing the material properties within the internal protrusion 101.

[0074] In some embodiments, the bottom wall of the first forming cavity 111 is provided with a groove 1111 extending radially from the inside to the outside. The cross-section of each groove 1111 has a top constriction. The bottom end of each extrusion petal has a limiting post 122. The bottom end of each limiting post 122 has a limiting part 1221 that slides and limits the groove 1111.

[0075] In this technical solution, the bottom limiting part 1221 of the limiting post 122 slides and is engaged in the sliding groove 1111 with the top constriction. This not only enables the radial smooth sliding of each extrusion petal, but also enables the reliable limiting of each extrusion petal in the height direction (that is, in the axial direction of the first forming cavity 111), further ensuring that each extrusion petal reliably and accurately extrudes the position of the protrusion 101 in each chamber.

[0076] In some embodiments, the radial displacement drive 13 is a regular N-shaped pyramid with a cross-section, where N is the number of radial extrusion petals and N≥3. The side of each radial extrusion petal away from the boss 101 inside the cabin is an inclined surface that gradually moves away from the corresponding side of the boss 101 inside the cabin from top to bottom. The inclined surface of each radial extrusion petal is respectively fitted and matched with each side of the regular N-shaped pyramid. In a specific embodiment, N=4, that is, the corresponding radial displacement drive 13 is a square pyramid.

[0077] In this technical solution, on the one hand, the sides of the regular N-shaped pyramid are fitted with the inner inclined surfaces of the radial extrusion petals to form a wedge-shaped fit. The radial displacement drive 13 can be used to drive the radial extrusion petals radially outward to complete the radial extrusion of the bosses 101 in each chamber. The structure is simple and the force application is reliable. On the other hand, the sides of the regular N-shaped pyramid can also be used to position the radial extrusion petals, ensuring that the radial extrusion petals deflect in the circumferential direction of the first forming cavity 111 during the radial extrusion process, further ensuring the efficient extrusion of the bosses 101 in each chamber by the radial extrusion petals.

[0078] In some embodiments, each of the regular N-shaped pyramids has a guide groove (not shown in the figure) extending from bottom to top on each side surface, with the top end of each guide groove being a sealing end and the bottom end being a through end. Each radial extrusion petal has a guide block (not shown in the figure) extending from bottom to top on its inclined surface. The guide block is slidably connected in each guide groove, and the cross-section of each guide block and the guide groove is a T-shape that matches each other. The guide block is slidably inserted into each guide groove through the through end of the guide groove, and the T-shape cooperation forms an anti-detachment limit for each guide block at the groove opening. In this way, on the one hand, the position of each radial extrusion petal in the height direction is more stable, ensuring efficient and reliable transmission of radial force. On the other hand, through the cooperation of the guide block and the guide groove with the top end being a sealing end, each radial extrusion petal can be gathered towards the center of the first forming cavity 111 during the rising of the regular N-shaped pyramid, and follow the rising of the regular N-shaped pyramid to realize the automatic demolding of each radial extrusion petal from the chamber, improving the work efficiency.

[0079] See details Figure 8 As shown, the top end of the radial displacement drive 13 is connected to the first upper template 141, and the lower end of the radial extrusion die 11 is connected to the first lower template 142. In actual use, the radial extrusion die 1 is connected to the lifting and force-applying end of the press via the aforementioned first upper template 141, and is fixedly connected to the working platform (which can be part of the press) via the aforementioned first lower template 142.

[0080] See also Figures 3 to 6 As shown, the forming device further includes an upsetting reverse extrusion die 2, comprising an upsetting reverse extrusion die 21 and a flat-bottomed conical punch 22 used in conjunction with it. The top end of the flat-bottomed conical punch 22 is connected to a second upper template 251, and the bottom end of the upsetting reverse extrusion die 21 is connected to a second lower template 252. The upsetting reverse extrusion die 2 is connected to the press and the working platform via the aforementioned second upper template 251 and second lower template 252. The upsetting reverse extrusion die 2 also includes a pressure plate 23, which is placed on top of the base bar stock 200 during upsetting to ensure reliable and uniform extrusion of the base bar stock 200. See details... Figure 6As shown, the upsetting reverse extrusion die 2 also includes a baffle plate 24 and multiple connecting rods 241 used in conjunction with it. When the upsetting base bar 200 is reverse extruded, the baffle plate 24 is connected to the opening of the second forming cavity (i.e., the top opening) of the upsetting reverse extrusion die 21 via the aforementioned connecting rods 241. After the reverse extrusion is completed, the baffle plate 24 can be used to demold the cylinder 201 from the flat-bottomed conical punch 22.

[0081] The aforementioned forming device also includes a fixture 31 and an arc welding gun. The arc welding gun includes a welding gun nozzle 32. During arc wire additive manufacturing, the prepared compartment substrate 100 is clamped and positioned on the fixture 31, and the welding gun nozzle 32 is inserted into the compartment substrate 100 to perform additive manufacturing on the corresponding inner wall area to form the corresponding inner boss 101. The aforementioned fixture 31 can be controlled to rotate a certain angle in a preset direction (e.g., clockwise or counterclockwise) (e.g., when there are four inner bosses 101, the rotation is 90°) and move in coordination with the welding gun nozzle to achieve segmented forming of inner bosses at different positions.

[0082] The forming process of the long and short inner bosses of the present invention is further described below in conjunction with the aforementioned molds:

[0083] (1) Specific steps for preparing the compartment substrate 100 using upsetting reverse extrusion die 2:

[0084] S11: Assemble the corresponding components such as the upsetting reverse extrusion die 21 and the flat-bottomed conical punch 22 on the press. Then, the flat-bottomed conical punch moves upward and is hoisted into the ejector rod 262 and the top plate 261 in sequence. Place the base bar 200 in the working cavity (i.e., the aforementioned second forming cavity) formed by the top plate 261 and the upsetting reverse extrusion die 21.

[0085] S12: The lifting plate 23 is placed above the bar stock, and the flat-bottomed conical punch 22 moves down to complete the upsetting;

[0086] S13: The flat-bottomed conical punch 22 moves upward, the ejector pin 262 lifts the top plate 261, the blank and the pressure plate 23, so that the pressure plate 23 pushes out the upsetting reverse extrusion die 21, and then the pressure plate 23 is lifted and removed, and the baffle plate 24 is installed.

[0087] S14: The flat-bottomed conical punch 22 moves downward to complete the reverse extrusion. Then, the connecting rod 241 is manually installed, and the flat-bottomed conical punch 22 moves upward to complete the demolding.

[0088] S15: Manually remove connecting rod 241, hoist and remove baffle plate 24, and then push rod 262 to push out top plate 261 and cylindrical foundation section (i.e., the aforementioned cylinder 201).

[0089] S16: After cooling to room temperature, the bottom is removed by machining to obtain a compartment without the inner boss (i.e., compartment base 100).

[0090] Before assembling the upsetting reverse extrusion die 21 and the flat-bottomed conical punch 22 of the upsetting reverse extrusion die 2 onto the press in S11, the process further includes: heating the bar stock (i.e., the aforementioned base bar stock 200) to the forming temperature (i.e., the aforementioned second forming temperature) and holding it at that temperature; preheating the flat-bottomed conical punch 22 and the upsetting reverse extrusion die 21 to above the bar stock forming temperature and holding them at that temperature to ensure that the forming temperature of the metal billet is reached, wherein the forming temperature is 470°C. Before placing the bar stock into the working cavity formed by the top plate 261 and the upsetting reverse extrusion die 21 in S11, the process further includes: applying an oil-based lubricant along the outer surface of the bar stock, the upper part of the top plate 261, and the interior of the upsetting reverse extrusion die 21 to achieve a labor-saving effect; the oil-based lubricant can be an oil-based graphite lubricant. The extrusion speed of the billet during upsetting and reverse extrusion is 0.5 mm / s - 1.5 mm / s. To prevent the forging process from being too slow and causing the billet and die temperature to be lower than the forming temperature, heat insulation cloth is used to wrap the outside of the die.

[0091] (2) Specific steps for forming the internal bosses 101 of each compartment using arc-wire additive manufacturing within the compartment substrate 100:

[0092] S21: Assemble the cylindrical compartment (i.e., the aforementioned compartment base 100) onto the fixture 31, and move the welding torch nozzle 32 to the position where the arc wire additive manufacturing inner boss (i.e., the aforementioned inner boss 101 of the compartment) is required.

[0093] S22: The welding torch nozzle 32 adds an inner boss layer by layer along the inner contour of the compartment using electric arc wire additive manufacturing. After being deposited to a set height, a transition fillet is added at the connection position between the inner boss and the compartment substrate 100.

[0094] S23: Fixture 31 rotates 90° counterclockwise to continue depositing the next inner boss until all inner bosses are formed.

[0095] S24: After the arc fuse additive manufacturing is completed, the material is unloaded to obtain a compartment containing four local internal bosses, which is then cooled to room temperature by air.

[0096] Specifically, the material used in the arc-wire additive manufacturing is 5356 aluminum alloy, and the wire feeding speed of the inner boss device in the arc-wire additive manufacturing is 8 mm / s, the welding speed is 20 mm / s, the welding voltage is 20 V, and the welding current is 130 A.

[0097] (3) Specific steps for radial extrusion of the bosses 101 in each compartment:

[0098] S31: Assemble the wedge block (i.e. the aforementioned radial displacement drive 13) and the radial extrusion die 11 on the press, place the section containing the inner boss into the working cavity (i.e. the aforementioned first forming cavity) of the radial extrusion die 11, and the press moves upward.

[0099] S32: The four segmented punches (i.e., the aforementioned radial extrusion segments) are hoisted and placed in sequence, so that the bottom guide rod of the segmented punch (i.e., the aforementioned limiting post 122) is aligned with the groove guide rail of the die (i.e., the aforementioned sliding groove 1111).

[0100] S33: The press slowly drives the wedge block downward, causing the segmented punch to radially extrude a certain distance. Then the punch moves upward. During the radial extrusion process, the amount of deformation of the additive blank and the blank at the interface between the additive and the substrate is relatively large, which can form a good strengthening effect on the blank.

[0101] S34: After radial extrusion is completed, the four segmented punches are hoisted away for unloading, and the material is cooled to room temperature by air.

[0102] S35: The flash is removed by machining to obtain a compartment with an inner boss.

[0103] Before assembling the punch and die components of the radial extrusion die onto the press in step S31, the process further includes: heating the billet to the forming temperature (i.e., the aforementioned first forming temperature) and holding it at that temperature; preheating the punch and die components to above the metal billet forming temperature and holding them at that temperature, wherein the forming temperature is 400°C. The overall extrusion speed of the section containing the inner boss chamber is 0.1 mm / s to promote full bonding between the additive and substrate interfaces and to ensure that the additive portion undergoes significant plastic deformation.

[0104] In summary, this invention provides a composite forming method and mold for flexible internal boss compartments. This method achieves integrated forming of complex internal boss compartments through composite processes. By leveraging radial extrusion molds and multi-parameter collaborative optimization, it effectively improves the microstructure of the interface between the additive boss and the cylinder wall, eliminating solidification defects. Compared with traditional riveting or welding processes, this invention not only avoids the problem of reduced load-bearing capacity caused by weak connection areas and stress concentration, but also combines the digital flexibility advantages of WAAM (Wire Arc Additive Manufacturing) to flexibly adjust the size, position, and morphology of the internal boss to meet the differentiated internal structure requirements of various missile compartments. This invention is particularly suitable for the composite forming of compartments with complex internal boss shapes and variable positions.

[0105] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method for forming a compartment section with an internal boss, characterized in that, Includes the following steps: Prepare the module substrate (100); Multiple internal bosses (101) are formed on the inner wall of the prepared compartment substrate (100) by means of arc wire additive manufacturing. At a first preset forming temperature, each of the internal bosses (101) of the compartment is radially extruded from the inside to the outside along the radial direction of the compartment base (100) to form a compartment having the internal bosses (101); at the first preset forming temperature, the rheological stress of the material of the internal bosses (101) is greater than the rheological stress of the material of the compartment base (100); the material of the internal bosses (101) is 5356 aluminum alloy, the material of the compartment base (100) is 7055 aluminum alloy, the first preset forming temperature is 400℃±30℃, and the radial extrusion speed for the internal bosses (101) is 0.1mm / s -1mm / s.

2. The forming method according to claim 1, characterized in that, The module substrate (100) is prepared and formed using the following steps: Upsetting matrix bar stock (200); The upset matrix bar (200) is reverse extruded to form a cylinder (201) with a bottom wall. The bottom wall of the cylindrical body (201) is removed to form the compartment base (100).

3. The forming method according to claim 2, characterized in that, The upsetting and reverse extrusion of the base bar (200) are carried out at a second preset forming temperature, and the second preset forming temperature is higher than the first preset forming temperature; and / or, the material of the compartment base (100) is 7055 aluminum alloy, and the extrusion speed of the upsetting and reverse extrusion of the base bar (200) is 0.5mm / s-1.5mm / s.

4. The forming method according to claim 1, characterized in that, The material of the boss (101) inside the cabin is 5356 aluminum alloy, and the arc-fused wire additive manufacturing is carried out using the following process parameters: The wire feed speed is 8 mm / s, the welding speed is 20 mm / s, the welding voltage is 20 V, and the welding current is 130 A; and / or, after depositing additive material to the target height on the boss (101) in each of the compartments, a transition fillet is added at the junction of the boss (101) in each compartment and the inner wall surface of the compartment substrate (100).

5. A forming apparatus for performing the forming method of a compartment section having an internal boss as described in any one of claims 1 to 4, characterized in that, The device includes a radial extrusion die (1), which includes a radial extrusion die (11), a radial extrusion punch (12), and a radial displacement drive (13). The radial extrusion die (11) includes a first forming cavity (111), and the radial extrusion punch (12) includes a plurality of radial extrusion petals arranged in a circle. The number of radial extrusion petals is equal to the number of bosses (101) inside the chamber. When the radial extrusion die (1) is used, each radial extrusion petal corresponds to each boss (101) inside the chamber. The radial displacement drive (13) can be driven to rise and fall to drive each radial extrusion petal to extrude each boss (101) inside the chamber from the inside out along the radial direction of the first forming cavity (111).

6. The forming apparatus according to claim 5, characterized in that, The bottom wall of the first forming cavity (111) is slidably connected to the bottom end of each of the radial extrusion valves; and / or, each of the radial extrusion valves includes a valve body and an outer boss (121) on the outer circular wall of the valve body, the outer boss (121) is detachably connected to the valve body, and the radial force-applying surface of the outer boss (121) matches the shape of the force-bearing surface of the inner boss (101) of the cabin.

7. The forming apparatus according to claim 6, characterized in that, The bottom wall of the first forming cavity (111) is provided with a groove (1111) extending radially from the inside to the outside. The cross-section of each groove (1111) has a top constriction. The bottom end of each extrusion petal has a limiting post (122). The bottom end of each limiting post (122) has a limiting part (1221) that slides and limits the groove (1111).

8. The forming apparatus according to claim 5, characterized in that, The radial displacement drive (13) is a regular N-shaped pyramid with a cross-section, where N is the number of radial extrusion petals and N≥3. The side of each radial extrusion petal away from the boss (101) inside the cabin is an inclined surface that gradually moves away from the corresponding side of the boss (101) inside the cabin from top to bottom. The inclined surface of each radial extrusion petal is respectively fitted and matched with each side of the regular N-shaped pyramid.

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