A circulating variable-diameter high-performance outer gradient structure aluminum-magnesium alloy pipe blank preparation die

Abstract

This invention discloses a high-performance aluminum-magnesium alloy tube blank preparation mold with cyclic diameter variation and external gradient structure, belonging to the field of metal plastic processing technology. The mold includes an upper mold assembly, a punch slide, a support box, a sliding assembly, a fixed push rod, and a lower template. The punch slide has left and right inner inclined surfaces of different heights, driving the sliding assembly to reciprocate horizontally. The sliding assembly includes left / right thrust sliders, upper / lower die boxes, a mold core, and left / right thrust rings. The mold core and the engaged die box form a coarse-diameter cavity and a fine-diameter cavity. The multi-lobed columnar strip at the end of the fixed push rod abuts against the thrust rings. This invention achieves multiple "diameter expansion-necking" cycles of the tube blank through a single downward movement of the punch slide, simultaneously completing geometric forming and external gradient structure construction in a single processing pass. It boasts high forming accuracy and strong gradient controllability. The prepared tube has a fine-grained, wear-resistant exterior and a coarse-grained, tough interior, making it suitable for high-end fields such as aerospace. The mold exhibits excellent versatility and maintainability, significantly improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing technology, specifically relating to a high-performance aluminum-magnesium alloy tube blank preparation mold with cyclic diameter variation and external gradient structure. It is suitable for one-time forming preparation of aluminum-magnesium alloy tube blanks and can simultaneously realize the geometric forming of the tube blank and the construction of the external gradient fine grain structure, thus producing a high-performance aluminum-magnesium alloy tube blank with fine external grains and coarse internal grains. Background Technology

[0002] High-performance lightweight aluminum-magnesium alloy tube blanks are increasingly in demand in aerospace, transportation, and high-end equipment manufacturing due to their light weight and high specific strength. In practical engineering applications, tube blanks are often subjected to combined loads such as bending, torsion, and wear, requiring the tube blank to have high wear resistance, high strength, and high fatigue performance on the outside, while maintaining good toughness on the inside. This means that an external gradient microstructure with fine grains on the outside and coarse grains on the inside is required.

[0003] Traditional aluminum-magnesium alloy tube blank manufacturing processes, such as extrusion and drawing, can only obtain a uniform microstructure, but cannot achieve a gradient distribution of the microstructure. Existing methods for preparing gradient microstructure tube blanks often rely on subsequent heat treatment, surface modification, or complex composite processes, which suffer from problems such as long process flows, high manufacturing costs, weak interfacial bonding strength, and poor controllability of the gradient microstructure. Some gradient microstructure tube blanks prepared by rotary reverse extrusion can only achieve an internal gradient structure with fine internal grains and coarse external grains, which contradicts the external gradient performance requirements of practical engineering.

[0004] Currently, there is a lack of a mold that can integrate the geometric shaping of tube blanks with the preparation of external gradient structures. This makes it impossible to simultaneously construct the cyclic diameter change and external gradient structure of the tube blank in a single-pass plastic processing, thus failing to meet the demand for efficient and short-process preparation of high-performance aluminum-magnesium alloy tube blanks with external gradient structures. To address this, this invention designs a cyclic diameter change high-performance aluminum-magnesium alloy tube blank preparation mold with external gradient structures. This mold achieves multiple "diameter expansion-necking" cycles of the tube blank through a single pressure stroke, utilizing the intense plastic deformation during the necking stage to construct the external gradient structure, thus overcoming the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems in existing aluminum-magnesium alloy tube blank preparation processes, such as the inability to simultaneously achieve geometric forming and external gradient microstructure construction, cumbersome preparation processes, and poor gradient controllability. This invention provides a high-performance aluminum-magnesium alloy tube blank preparation mold with cyclic diameter variation and external gradient microstructure. The mold uses a customized contoured punch slide to drive a sliding component in horizontal reciprocating motion, causing the tube blank to undergo multiple "diameter expansion-necking" cyclic deformations. Utilizing the radial compression and directional metal flow during the necking stage, large plastic strain accumulates on the outer side of the tube wall, achieving a gradient grain size distribution from the surface inwards. This ultimately produces a high-performance aluminum-magnesium alloy tube blank with fine outer grains and coarse inner grains. Furthermore, the mold structure has a high degree of integration, high forming accuracy, and strong controllability of the gradient microstructure.

[0006] To achieve the above objectives, the solution of the present invention is as follows:

[0007] A die for preparing high-performance aluminum-magnesium alloy tube blanks with cyclic variable diameter and external gradient structure includes an upper die assembly, a punch slide, a support box, a sliding assembly, a left fixed push rod, a right fixed push rod, and a lower template. The upper die assembly is connected to the upper slide of a press. The punch slide is fixedly connected to the upper die assembly. The punch slide has a downwardly extending left support rod and a right support rod. The left support rod has a left inner upper inclined surface and a left inner lower inclined surface, and the right support rod has a right inner upper inclined surface and a right inner lower inclined surface. The heights of the left inner upper inclined surface and the left inner lower inclined surface are both lower than the heights of the right inner upper inclined surface and the right inner lower inclined surface. The support box serves as the main support frame and is fixed to the lower template. The lower template is connected to the press worktable. The top of the support box has an insertion port for the left and right support rods to be inserted downwards. The sliding assembly includes a left thrust slider, a right thrust slider, an upper die box, a lower die box, a die core, a left thrust ring, and a right thrust ring. The upper die box and the lower die box are fastened together. The radius of the left half of the die core is larger than the radius of the right half of the die core, forming a shaft-like structure with a variable diameter in the middle. The die core is placed inside the upper die box and the lower die box. After fastening, the upper die box and the lower die box form a coarse-diameter cavity in the left half of the die core and a fine-diameter cavity in the right half of the die core. Since the radius of the left half of the die core is larger than the radius of the right half of the die core, the radius of the coarse-diameter cavity is larger than the radius of the fine-diameter cavity. There is a gap between the die core and the fine-diameter cavity and the coarse-diameter cavity for the tube blank, the left thrust ring, and the right thrust ring to be fitted on the die core. The left thrust ring and the right thrust ring are used to abut against the tube blank when pushing it. The left and right thrust sliders are respectively clamped to both sides of the upper and lower die housings. A left fixed push rod passes through the middle of the left thrust slider. One end of the left fixed push rod is fixed to the inner wall of the support housing, and the other end extends into the large-diameter cavity and abuts against the left thrust ring. A right fixed push rod passes through the middle of the right thrust slider. One end of the right fixed push rod is fixed to the inner wall of the support housing, and the other end extends into the small-diameter cavity and abuts against the right thrust ring. The left thrust slider has a left outer upper inclined surface for engaging with the left inner lower inclined surface of the punch slide, and a left outer lower inclined surface for engaging with the left inner upper inclined surface of the punch slide. The right thrust slider has a right outer upper inclined surface for engaging with the right inner lower inclined surface of the punch slide, and a right outer lower inclined surface for engaging with the right inner upper inclined surface of the punch slide. Through the engagement of the inclined surfaces, the vertical pressure of the punch slide is converted into a horizontal thrust that pushes the left and right thrust sliders to move horizontally.

[0008] Furthermore, the narrow-diameter cavity and the coarse-diameter cavity are each provided with a semi-circular groove on the upper and lower die boxes. After the upper and lower die boxes are fastened together, the upper and lower semi-circular grooves are combined to form the narrow-diameter cavity and the coarse-diameter cavity.

[0009] Furthermore, the outer walls of the upper and lower die boxes are provided with guide grooves at the positions corresponding to the left and right thrust sliders, respectively. The left and right thrust sliders are each provided with guide blocks. The direction of the guide grooves is perpendicular to the movement path of the upper and lower die boxes. Through the cooperation of the guide grooves and guide blocks, the left and right thrust sliders slide and are respectively clamped to both sides of the upper and lower die boxes.

[0010] Furthermore, the support box is provided with a placement platform for placing the lower mold box, and the placement platform is provided with guide rails for the lower mold box to slide horizontally.

[0011] Furthermore, the left fixed push rod and the right fixed push rod are coaxially arranged.

[0012] Furthermore, one end of the left fixed push rod is fixed to the inner wall of the support box by fasteners, and the other end of the left fixed push rod extends axially into a multi-lobed columnar strip. The multi-lobed columnar strips are arranged in a ring at intervals and extend into the coarse-diameter cavity, directly acting on the left thrust ring. The right fixed push rod has the same structural design as the left fixed push rod, but the radius of the right fixed push rod is smaller than that of the left fixed push rod.

[0013] Furthermore, the two ends of the mold core extend beyond the upper and lower mold box bodies. The left and right push sliders each have a central groove and a multi-lobed hole surrounding the edge of the central groove. The shape and number of the multi-lobed holes correspond to the shape and number of the columnar strips. The mold core is embedded in the central groove through the protruding parts at both ends, and the columnar strips of the left and right fixed push rods are embedded in the multi-lobed holes.

[0014] Furthermore, the upper mold assembly is detachably connected to the upper slide of the press by bolts, and the lower mold plate is detachably connected to the press worktable by bolts.

[0015] Furthermore, the mold also includes an ejection mechanism integrated into the support box, which is used to eject the sliding component after molding is completed.

[0016] This invention, through an innovative structural design that converts vertical pressure into horizontal reciprocating thrust, achieves the integration of geometric forming and external gradient microstructure construction of aluminum-magnesium alloy tubing. Compared with existing technologies, it has the following significant advantages: 1. Integrated shaping and tissue construction, highly efficient process. This mold can drive the sliding component to complete multiple "diameter expansion-neck reduction" cycles by moving the punch slide vertically downwards in a single pass. It can simultaneously achieve tube geometry forming and external gradient structure construction in a single plastic forming process, without the need for subsequent heat treatment or surface modification, which greatly reduces the production cycle and preparation cost.

[0017] 2. The external gradient structure offers strong controllability and precise, adjustable performance. By adjusting the height difference and contour design of the left and right inner lower inclined surfaces of the punch slide, the number of "expansion-necking" cycles can be precisely controlled; by changing the radius difference between the coarse-diameter cavity and the fine-diameter cavity and optimizing the distribution of the multi-lobed columnar strips of the fixed push rod, the direction of metal flow and the amount of strain accumulation on the outside of the tube wall can be flexibly adjusted, thereby achieving precise control of the depth of the external gradient structure layer (0.8-1.2mm) and the performance gradient, meeting the performance requirements of different application scenarios.

[0018] 3. High forming precision and good product consistency The guide grooves of the upper and lower inner mold boxes are precisely matched with the guide blocks of the thrust slider, which effectively restricts the movement direction of the sliding components; the left and right fixed push rods are set coaxially to ensure that the tube blank is subjected to uniform force and avoid bending deformation; the lower concave mold box slides along the linear guide rail, which further improves the motion accuracy and significantly improves product consistency.

[0019] 4. Excellent mold versatility and maintainability Key components such as the upper mold assembly, lower mold plate, and fixed push rod are all connected by detachable bolts, facilitating installation, debugging, and maintenance. The upper / lower die box, mold core, and thrust ring can be quickly replaced according to the forming requirements of different sized tube blanks, eliminating the need to redesign the entire mold and significantly improving its versatility and reusability. The central groove and multi-lobed hole design of the thrust slider achieves precise positioning of the mold core and fixed push rod, reducing assembly difficulty.

[0020] 5. The prepared pipes have excellent performance and wide adaptability. The prepared aluminum-magnesium alloy pipes form a fine-grained gradient structure on the outside while maintaining a coarse-grained structure and good toughness inside. They can withstand combined loads such as bending and torsion, and are fully adapted to the stringent requirements for high-performance lightweight pipes in aerospace, transportation, and high-end equipment manufacturing.

[0021] 6. Stable and reliable operation, high production efficiency. The left and right support rods of the punch slide extend precisely into the socket at the top of the support box, and cooperate stably with the inclined surface of the thrust slider, resulting in efficient power transmission. The hydraulic ejection mechanism integrated into the support box can quickly eject the sliding component after forming, making it easy to remove the tube, which greatly improves production efficiency and reduces the labor intensity of operators. Attached Figure Description

[0022] Figure 1 This is an exploded view of the mold of the present invention; Figure 2 This is a schematic diagram of the mold assembly of the present invention; Figure 3 This is a schematic diagram of the interior of the mold of the present invention (the front cover plate is omitted). Figure 4This is a structural schematic diagram of the upper / lower concave mold box of the present invention; Figure 5 for Figure 4 Enlarged view of point A in the middle; Figure 6 This is a schematic diagram of the structure of the mold core of the present invention; Figure 7 This is a schematic diagram of the right thrust slider of the present invention; Figure 8 This is a schematic diagram of the structure of the left thrust ring and the right thrust ring of the present invention; Figure 9 This is a schematic diagram of the structure of the left fixed push rod / right fixed push rod of the present invention; Figure 10 This is a schematic diagram of the support box of the present invention; Figure 11 This is a schematic diagram of the working process of the present invention.

[0023] Labeling Explanation: 1. Upper mold assembly; 2. Punch slide plate; 3. Support box; 4. Left fixed push rod; 5. Right fixed push rod; 6. Left support rod; 7. Right support rod; 8. Right thrust ring; 9. Left inner lower inclined surface; 10. Right inner lower inclined surface; 11. Left thrust slider; 12. Right thrust slider; 13. Central groove; 14. Multi-lobed hole; 17. Upper die box; 18. Lower die box; 19. Back pressure chamber; 20. Columnar strip; 21. Insert; 2 3. Push rod fixing hole; 82. Left thrust ring; 25. Mold core; 26. Lower template; 27. Large diameter cavity; 28. Small diameter cavity; 29. ​​Gap; 30. Tube blank; 31. Left outer upper inclined surface; 32. Right outer upper inclined surface; 33. Semi-circular groove; 34. Guide block; 35. Guide groove; 36. Placement platform; 37. Square groove; 38. Front cover plate; 39. Left inner upper inclined surface; 40. Right inner upper inclined surface; 41. Left outer lower inclined surface; 42. Right outer lower inclined surface. Detailed Implementation

[0024] 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 preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a high-performance aluminum-magnesium alloy tube blank preparation mold with cyclic diameter variation and external gradient structure. The high-performance aluminum-magnesium alloy tube preparation mold with cyclic diameter variation and external gradient structure described in this invention can realize the synchronous construction of the geometric forming and external gradient structure of the aluminum-magnesium alloy tube. By driving the sliding component to move horizontally back and forth through the vertical movement of the punch slide, the tube blank is completed in multiple expansion-neck cycles, and finally a high-performance aluminum-magnesium alloy tube with fine external grains and coarse internal grains is prepared.

[0026] like Figure 1 , Figure 2 and Figure 3 As shown, the mold includes an upper mold assembly 1, a punch slide plate 2, a support box 3, a sliding assembly, a left fixed push rod 4, a right fixed push rod 5, and a lower template 26. The upper mold assembly 1 is connected to the upper slide block of the press, and the punch slide plate 2 is fixedly connected to the upper mold assembly 1. The punch slide plate 2 is provided with a downwardly extending left support rod 6 and a right support rod 7. The left support rod 6 is provided with a left inner upper inclined surface 39 and a left inner lower inclined surface 9, and the right support rod 7 is provided with a right inner upper inclined surface 40 and a right inner lower inclined surface 10. The heights of the left inner upper inclined surface 39 and the left inner lower inclined surface 9 are both lower than the heights of the right inner upper inclined surface 40 and the right inner lower inclined surface 10. The support box 3 is fixed to the lower template 26 as the main support frame. The lower template 26 is connected to the press worktable. The top of the support box 3 is provided with a socket 21 for the left support rod 6 and the right support rod 7 to be inserted downwards. When the punch slide 2 moves vertically with the upper mold assembly 1, the left support rod 6 and the right support rod 7 can be precisely inserted downwards into the support box 3 through the socket 21 to achieve precise cooperation with the sliding assembly and ensure the stability of power transmission. The contour of the punch slide 2 is specially designed to control the reciprocating motion of the sliding assembly to achieve multiple "diameter expansion-neck reduction" cycles in a specific area of ​​the tube blank 30.

[0027] The sliding assembly includes a left thrust slider 11, a right thrust slider 12, an upper die housing 17, a lower die housing 18, a mold core 25, a left thrust ring 82, and a right thrust ring 8. The upper die housing 17 and the lower die housing 18 are fastened together, as shown below. Figure 6 As shown, the radius of the left half of the mold core 25 is larger than that of the right half of the mold core 25, forming a shaft-like structure with a variable diameter in the middle. The mold core 25 is placed inside the upper mold box 17 and the lower mold box 18, as shown. Figure 11 As shown, after the upper die box 17 and lower die box 18 are engaged, a coarse-diameter cavity 27 is formed in the left half of the die core 25, and a fine-diameter cavity 28 is formed in the right half of the die core 25. Since the radius of the left half of the die core 25 is larger than the radius of the right half of the die core 25, the radius of the coarse-diameter cavity 27 is larger than the radius of the fine-diameter cavity 28. A gap 29 is provided between the die core 25 and the fine-diameter cavity 28 and the coarse-diameter cavity 27 for the tube blank 30, the left thrust ring 82 and the right thrust ring 8 to be fitted onto the die core 25 (the radius of the left thrust ring 82 is larger than the radius of the right thrust ring 8, such as...). Figure 8As shown), the left thrust ring 82 and the right thrust ring 8 are used to abut against the tube blank 30 when pushing the tube blank 30, and the radial deformation of the tube blank 30 is achieved by the abutment of the thrust rings when the sliding assembly moves. The left thrust slider 11 and the right thrust slider 12 are respectively clamped to both sides of the upper die box 17 and the lower die box 18, realizing the fixed connection between the upper die box 17 and the lower die box 18 and ensuring the synchronicity of movement. The left fixed push rod 4 passes through the middle of the left thrust slider 11, and one end of the left fixed push rod 4 is fixed to the inner wall of the support box 3 (e.g., Figure 10 As shown, a square groove 37 is provided on the inner wall of the support box 3, and a push rod fixing hole 23 is opened in the groove. The other end extends into the large diameter cavity 27 and abuts against the left thrust ring 82. The right fixed push rod 5 passes through the middle of the right thrust slider 12. One end of the right fixed push rod 5 is fixed to the inner wall of the support box 3, and the other end extends into the small diameter cavity 28 and abuts against the right thrust ring 8. The left thrust slider 11 is provided with a left outer upper inclined surface 31 for cooperating with the left inner lower inclined surface 9 of the punch slide plate 2 and a left outer lower inclined surface 41 for cooperating with the left inner upper inclined surface 39 of the punch slide plate 2. The right thrust... The slider 12 has a right outer upper inclined surface 32 for engaging with the right inner lower inclined surface 10 of the punch slide 2, and a right outer lower inclined surface 42 for engaging with the right inner upper inclined surface 40 of the punch slide 2. Through the engagement of the inclined surfaces, the vertical pressure of the punch slide 2 is converted into a horizontal thrust that pushes the left thrust slider 11 and the right thrust slider 12 to move horizontally, thereby driving the die box and the die core 25 to move horizontally synchronously. In this embodiment, the tilt angle is set to 40°, which can be flexibly adjusted according to the actual required thrust transmission efficiency and the moving speed of the sliding components. The outer walls of the upper die box 17 and the lower die box 18 are respectively provided with guide grooves 35 at the positions corresponding to the left thrust slider 11 and the right thrust slider 12, combined with Figure 1 and 7 As shown, the left thrust slider 11 and the right thrust slider 12 are each provided with a guide block 34. The direction of the guide groove 35 is perpendicular to the movement path of the upper die box 17 and the lower die box 18. Through the cooperation of the guide groove 35 and the guide block 34, the left thrust slider 11 and the right thrust slider 12 slide and are respectively clamped on both sides of the upper die box 17 and the lower die box 18.

[0028] like Figure 4 and Figure 5As shown, the narrow-diameter cavity 28 and the coarse-diameter cavity 27 are each provided with a semi-circular groove 33 on the upper die box 17 and the lower die box 18. After the upper die box 17 and the lower die box 18 are fastened together, the upper and lower semi-circular grooves 33 merge to form a complete circular narrow-diameter cavity 28 and a coarse-diameter cavity 27. This structure facilitates the placement of the mold core 25 and the clamping of the tube blank 30, while ensuring the smoothness of the inner walls of the narrow-diameter cavity 28 and the coarse-diameter cavity 27, avoiding problems such as scratches and uneven wall thickness during the forming process of the tube blank 30. In this embodiment, the inner diameter of the narrow-diameter cavity 28 is adapted to the target inner diameter of the tube blank 30 after forming, and the inner diameter of the coarse-diameter cavity 27 is 8-10 mm larger than that of the narrow-diameter cavity 28, providing sufficient space for the metal flow of the tube blank 30. A back pressure chamber 19 with a diameter transition is formed between the coarse diameter cavity 27 and the fine diameter cavity 28. The back pressure chamber 19 has several annular grooves in the radial direction to provide radial flow space for the tube blank.

[0029] The support box 3 has a placement platform 36 inside for placing the lower die box 18. The placement platform 36 is provided with a guide rail (not shown in the figure) for the lower die box 18 to slide horizontally. The guide rail is a linear guide rail that fits against the bottom of the lower die box 18. After the upper die box 17 and the lower die box 18 are engaged, they can slide horizontally back and forth along the guide rail. The setting of the guide rail further improves the accuracy of the movement of the lower die box 18, while reducing the frictional resistance between the lower die box 18 and the placement platform 36, reducing the wear of the mold components, and extending the service life of the mold.

[0030] The left fixed push rod 4 and the right fixed push rod 5 are coaxially arranged, with the coaxiality error controlled within 0.02mm. This ensures that the contact force between the left thrust ring 82 and the right thrust ring 8 and the tube blank 30 is on the same straight line, preventing the tube blank 30 from bending or deforming due to force offset, and ensuring the straightness and coaxiality of the tube blank 30 after forming. The dimensions of the left thrust ring 82 and the right thrust ring 8 are adapted to the radial dimension of the tube blank 30, and the thrust rings at both ends are placed within the gap 29. Through the cooperation of the fixed push rods and thrust rings, the tube blank 30 is axially fixed, preventing axial movement of the tube blank 30 during the forming process.

[0031] One end of the left fixed push rod 4 is fixed to the inner wall of the support box 3 by fasteners. The fasteners are bolts, which fit into the screw holes on the push rod, ensuring a secure fixation and facilitating disassembly and adjustment. Figure 9As shown, the other end of the left fixed push rod 4 extends axially into a multi-lobed columnar strip 20. The multi-lobed columnar strip 20 is arranged in a ring with intervals. The multi-lobed columnar strip 20 extends into the coarse-diameter cavity 27. In this embodiment, the columnar strip 20 is set to four lobes, which are arranged in a cross-shaped ring with intervals. This can achieve stable contact with the left thrust ring 82 and reserve clearance space for metal flow. The radius of the columnar strip 20 of the left fixed push rod 4 is adapted to the radius of the coarse-diameter cavity 27 and directly acts on the left thrust ring 82. The right fixed push rod 5 has the same structural design as the left fixed push rod 4. Its end is also provided with a four-lobed ring with intervals. It extends into the fine-diameter cavity 28 and abuts against the right thrust ring 8. However, the radius of the right fixed push rod 5 is smaller than the radius of the left fixed push rod 4 and is adapted to the radius of the fine-diameter cavity 28 to ensure precise contact between the fixed push rod and the thrust ring.

[0032] The two ends of the mold core 25 extend beyond the upper mold box 17 and the lower mold box 18. The left and right push sliders 11 and 12 each have a central groove 13 and a multi-lobed hole 14 surrounding the edge of the central groove 13. The multi-lobed hole 14 corresponds to the shape and number of the columnar strips 20. In this embodiment, the multi-lobed hole 14 is a four-lobed hole adapted to the four-lobed columnar strips 20. The mold core 25 is embedded in the central groove 13 through the protruding parts at both ends, so as to achieve precise positioning of the mold core 25 with the left and right push sliders 11 and 12, and ensure the synchronous movement of the mold core 25 and the push sliders. The columnar strips 20 of the left fixed push rod 4 and the right fixed push rod 5 are embedded in the multi-lobed hole 14. The columnar strips 20 can slide relative to each other along the multi-lobed hole 14, which does not affect the horizontal movement of the push slider, and can further restrict the circumferential rotation of the push slider through the cooperation of the columnar strips 20 and the multi-lobed hole 14, thereby improving the stability of the movement.

[0033] The upper mold assembly 1 is detachably connected to the upper slide of the press by bolts, and the lower template 26 is detachably connected to the press worktable by bolts. All connection parts are fastened with high-strength bolts, which are firm and easy to disassemble, facilitating the installation, debugging, maintenance and replacement of parts of the mold. The mold can be quickly replaced with a suitable cavity box, mold core 25 and thrust ring according to the forming requirements of different specifications of tube blank 30, thereby improving the versatility of the mold.

[0034] The mold also includes an ejection mechanism (not shown in the figure), which is integrated on the support box 3. It is used to eject the sliding component after the forming is completed, so that the operator can take out the formed tube and greatly improve production efficiency.

[0035] The mold also includes a front cover plate 38, which can be detachably covered on the front of the support box 3 to facilitate maintenance of the interior of the support box 3.

[0036] Combination Figures 1 to 11 Please refer to the following: Figure 11The specific operating procedure for preparing high-performance aluminum-magnesium alloy tubing with cyclic diameter variation and external gradient structure using this mold is as follows: S1 Mold Assembly and Blank 30 Preparation: The lower mold plate 26 is fixed to the press workbench with bolts. The support box 3 is fixed to the lower mold plate 26. The lower die box 18 is placed on the guide rail inside the support box 3. The mold core 25 is placed in the semi-circular groove 33 of the lower die box 18. The aluminum-magnesium alloy blank 30 is preheated to 350-450℃ for 30-60 minutes. The preheated blank 30 is placed on the smaller right half of the mold core 25. The left thrust ring 82 and right thrust ring 8 are respectively fitted onto both ends of the blank 30. The upper die box 17 is fastened onto the lower die box 18, forming a complete fine-diameter cavity 28 and a coarse-diameter cavity 27. Then, the left thrust slider 11 and right thrust slider 12 are successively tightened onto... After the die box is snapped together, the two protruding parts of the die core 25 are embedded in the central groove 13 of the two thrust sliders, thus completing the assembly of the sliding components. After the upper die assembly 1 is fixedly connected to the punch slide 2, it is installed on the upper slide of the press with bolts. The position of the press is adjusted so that the left support rod 6 and the right support rod 7 of the punch slide 2 are aligned with the insertion port 21 at the top of the support box 3. One end of the left fixed push rod 4 and one end of the right fixed push rod 5 are fixed to the corresponding positions on the inner wall of the support box 3 with fasteners. The columnar strip 20 of the other end is inserted into the multi-lobed hole 14 of the left thrust slider 11 and the right thrust slider 12 respectively. The left thrust ring 82 abuts against the columnar strip 20 of the left fixed push rod 4 and the right thrust ring 8 abuts against the columnar strip 20 of the right fixed push rod 5. S2 Expansion Stage: The press is started, and the press drives the upper mold assembly 1 to move the punch slide 2 vertically downward. The left support rod 6 of the punch slide 2 extends into the support box 3 along the insertion port 21. The left inner lower slope 9 of the left support rod 6 first fits with the left outer upper slope 31 of the left thrust slider 11, converting the vertical pressure into a horizontal rightward thrust, which pushes the left thrust slider 11 to drive the upper die box 17, the lower die box 18 and the mold core 25 to slide horizontally to the right along the guide rail. At this time, the tube blank 30 is kept in a fixed position under the axial limit of the left fixed push rod 4, the right fixed push rod 5 and the thrust ring. The stepped shaft structure of the mold core 25 cooperates with the small diameter cavity 28 and the large diameter cavity 27 of the die box. Under the action of pressure, the metal flows in a direction towards the large diameter cavity 27, realizing radial expansion deformation of the tube blank 30. The outer diameter of the tube blank 30 gradually expands with the movement of the die box, completing the first expansion.

[0037] S3 Necking and External Gradient Structure Formation Stage: The punch slide 2 continues to move vertically downwards. Since the height of the left inner lower slope 9 is lower than the height of the right inner lower slope 10, the right support rod 7 of the punch slide 2 moves downwards and extends into the support box 3. The left inner lower slope 9 of the left support rod 6 moves away from the left outer upper slope 31 of the left thrust slider 11. The right inner lower slope 10 of the right support rod 7 is in contact with the right outer upper slope 32 of the right thrust slider 12, pushing the right thrust slider 12 to drive the upper die box 17, lower die box 18, and die core 25 to slide horizontally to the left along the guide rail. The billet 30 enters the necking deformation stage; this stage is the core of the external gradient structure construction. The billet 30 is subjected to radial compression, which increases the wall thickness. Under pressure, the metal flows directionally towards the narrow diameter cavity 28. The metal on the outside of the tube wall is in direct contact with the inner wall of the die box, that is, it is squeezed at the back pressure cavity 19. It undergoes severe shearing and compression deformation, and accumulates large plastic strain to achieve grain refinement. Meanwhile, the strain of the metal on the inside of the tube wall gradually decreases with increasing depth, eventually forming an external gradient structure in which the grain size gradually increases from the surface to the inside. The downward movement of the punch slide 2 stops.

[0038] S4 Cyclic Forming and Demolding: By controlling the height difference and contour design of the left inner lower inclined surface 9 and the right inner lower inclined surface 10 of the punch slide 2, the punch slide 2 is controlled to move vertically upwards and return. The left inner upper inclined surface 39 of the left support rod 6 is in contact with the left outer lower inclined surface 41 of the left thrust slider 11, converting the vertical pressure into a horizontal thrust to the right. This again drives the upper die box 17, the lower die box 18, and the die core 25 to slide horizontally to the right along the guide rail, repeating the same diameter expansion process as in step S2, thus completing one stroke. Multiple horizontal reciprocating motions are performed to achieve multiple "diameter expansion-neck reduction" cycles of the tube blank 30. In this embodiment, the number of cycles is set to 2 to further increase the strain accumulation on the outer side of the tube wall and optimize the layer depth and performance gradient of the external gradient structure. After the tube blank 30 is formed, the ejection mechanism integrated into the support box 3 is activated to eject the sliding component as a whole out of the support box 3. The operator disassembles the upper concave mold box 17 and the lower concave mold box 18, and takes out the formed aluminum-magnesium alloy tube to complete the entire preparation process.

[0039] In this embodiment, the aluminum-magnesium alloy tube prepared by the above-mentioned mold and process has an external fine grain layer depth of 0.8-1.2mm, an external tensile strength increase of more than 30%, a wear resistance increase of more than 40%, and maintains good internal toughness. It can withstand combined loads such as bending and torsion, fully meeting the needs of aerospace, transportation, high-end equipment manufacturing and other fields for high-performance aluminum-magnesium alloy tubes. At the same time, the mold components are precisely matched and have strong motion stability. The dimensional tolerance of the formed tube can be controlled within ±0.1mm. Moreover, the mold is highly versatile and easy to maintain, and can be adapted to the forming and preparation of aluminum-magnesium alloy tubes of different specifications.

[0040] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the design of this case. All equivalent changes made based on the key design features of this case shall fall within the protection scope of this case.

Claims

1. A die for preparing high-performance aluminum-magnesium alloy tube blanks with cyclic variable diameter and external gradient structure, comprising an upper die assembly, a punch slide, a support box, a sliding assembly, a left fixed push rod, a right fixed push rod, and a lower template; the upper die assembly is connected to the upper slide of a press, the punch slide is fixedly connected to the upper die assembly, the punch slide is provided with a downwardly extending left support rod and a right support rod, the left support rod is provided with a left inner upper inclined surface and a left inner lower inclined surface, the right support rod is provided with a right inner upper inclined surface and a right inner lower inclined surface, the height of the left inner upper inclined surface and the left inner lower inclined surface is lower than the height of the right inner upper inclined surface and the right inner lower inclined surface, the support box is fixed to the lower template as the main support frame, the lower template is connected to the press worktable, and the top of the support box is provided with an insertion port for the left and right support rods to be inserted downwards; The sliding assembly includes a left thrust slider, a right thrust slider, an upper die box, a lower die box, a die core, a left thrust ring, and a right thrust ring. The upper die box and the lower die box are fastened together. The radius of the left half of the die core is larger than the radius of the right half of the die core, forming a shaft-like structure with a variable diameter in the middle. The die core is placed inside the upper die box and the lower die box. After fastening, the upper die box and the lower die box form a coarse-diameter cavity in the left half of the die core and a fine-diameter cavity in the right half of the die core. Since the radius of the left half of the die core is larger than the radius of the right half of the die core, the radius of the coarse-diameter cavity is larger than the radius of the fine-diameter cavity. There is a gap between the die core and the fine-diameter cavity and the coarse-diameter cavity for the tube blank, the left thrust ring, and the right thrust ring to be fitted on the die core. The left thrust ring and the right thrust ring are used to abut against the tube blank when pushing it. The left and right thrust sliders are respectively clamped to both sides of the upper and lower die housings. A left fixed push rod passes through the middle of the left thrust slider. One end of the left fixed push rod is fixed to the inner wall of the support housing, and the other end extends into the large-diameter cavity and abuts against the left thrust ring. A right fixed push rod passes through the middle of the right thrust slider. One end of the right fixed push rod is fixed to the inner wall of the support housing, and the other end extends into the small-diameter cavity and abuts against the right thrust ring. The left thrust slider has a left outer upper inclined surface for engaging with the left inner lower inclined surface of the punch slide, and a left outer lower inclined surface for engaging with the left inner upper inclined surface of the punch slide. The right thrust slider has a right outer upper inclined surface for engaging with the right inner lower inclined surface of the punch slide, and a right outer lower inclined surface for engaging with the right inner upper inclined surface of the punch slide. Through the engagement of the inclined surfaces, the vertical pressure of the punch slide is converted into a horizontal thrust that pushes the left and right thrust sliders to move horizontally.

2. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The narrow-diameter cavity and the coarse-diameter cavity are each provided with a semi-circular groove on the upper and lower die boxes. After the upper and lower die boxes are fastened together, the upper and lower semi-circular grooves are combined to form the narrow-diameter cavity and the coarse-diameter cavity.

3. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The outer walls of the upper and lower die boxes are provided with guide grooves at the positions corresponding to the left and right thrust sliders, respectively. The left and right thrust sliders are each provided with guide blocks. The direction of the guide grooves is perpendicular to the movement path of the upper and lower die boxes. Through the cooperation of the guide grooves and guide blocks, the left and right thrust sliders slide and are respectively clamped to both sides of the upper and lower die boxes.

4. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The support box is equipped with a placement platform for placing the lower mold box, and the placement platform is equipped with guide rails for the lower mold box to slide horizontally.

5. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The left fixed push rod and the right fixed push rod are coaxially arranged.

6. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, One end of the left fixed push rod is fixed to the inner wall of the support box by fasteners, and the other end of the left fixed push rod extends axially into a multi-lobed columnar strip. The multi-lobed columnar strips are arranged in a ring at intervals and extend into the coarse-diameter cavity, directly acting on the left thrust ring. The right fixed push rod has the same structural design as the left fixed push rod, but the radius of the right fixed push rod is smaller than that of the left fixed push rod.

7. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 6, characterized in that, The two ends of the mold core extend beyond the upper and lower mold box bodies. The left and right push sliders each have a central groove and a multi-lobed hole surrounding the edge of the central groove. The shape and number of the multi-lobed holes correspond to the shape and number of the columnar strips. The mold core is embedded in the central groove through the protruding parts at both ends, and the columnar strips of the left and right fixed push rods are embedded in the multi-lobed holes.

8. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The upper mold assembly is detachably connected to the upper slide of the press by bolts, and the lower mold plate is detachably connected to the press worktable by bolts.

9. The die for preparing a high-performance aluminum-magnesium alloy tube blank with cyclic diameter variation and external gradient structure according to claim 1, characterized in that, The mold also includes an ejection mechanism, which is integrated into the support box and is used to eject the sliding component after molding is completed.

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