A pneumatic skin correction device and method

Abstract

This application provides a pneumatic skin shaping device and method. The die and base of the shaping device have an interlocking function in their natural state. When the coil is energized, it provides ultra-high pressure side weight and releases ignition sparks via magnetic force transmission. Explosives are placed inside the shaping device. When the coil is energized, the device is energized, and the magnetic force induces a magnetic induction switch to discharge and detonate the explosive, instantly generating high-temperature, ultra-high-pressure gas that impacts the inner surface of the semi-finished product. After the explosion, the coil is continuously energized, and the magnetization between the die and base generates ultra-high pressure side weight, sealing the heat energy of the explosion and prolonging the high-pressure residence time. This causes the inner surface material of the semi-finished product to be thermally compacted, resulting in microscopic shrinkage of the grain area and the formation of surface tension to counteract rebound. This application has significant advantages such as high load capacity, low energy consumption, and high speed, and can overcome the problem of poor molding accuracy in large aluminum alloy pneumatic skins due to factors such as solution incubation period, equipment platform size, and tonnage.

Description

Technical Field

[0001] This application belongs to the field of plastic processing technology, specifically relating to a pneumatic skin shaping device and method. Background Technology

[0002] To meet the requirements of forming complex thin-walled components while extending service life, most aluminum alloys require rapid heating at approximately 500°C after forming, followed by rapid cooling in water at room temperature. The severe deformation caused by rapid heating and cooling has become a major challenge restricting the improvement of molding accuracy and yield of thin-walled components. This is because the incubation period for maintaining excellent plasticity after solution treatment is generally 0.5 hours. Exceeding the specified time results in age hardening and a sharp decrease in plasticity, which multiplies the difficulty of shaping and makes cracking more likely.

[0003] Currently, the main operation method for sheet metal heat treatment straightening is as follows: first, use a rubber sheet to quickly strike areas of severe internal stress concentration in the part immediately after solution treatment; then, use a metal hammer to further even out the stress distribution. Common problems with this method are as follows: First, rubber striking or hammering involves point-by-point, area-by-area straightening. Defects such as loosening and bulging in thin-walled parts alternate between different straightening zones, resulting in low efficiency. Second, it relies heavily on skill and experience. For the same product, the straightening sequence and force vary significantly depending on the operator's skill and the degree of solution deformation. This is especially true for large, complex, thin-walled parts where solution deformation straightening and molding are more difficult, easily leading to improper straightening or even worsening of the molding effect.

[0004] The essence of shaping is to utilize the uniform distribution of internal stress to disperse a severe macroscopic defect into multiple extremely small, approximate microscopic defects, making the finished part as close as possible to the theoretical surface under reasonable stress maintenance. However, the formation mechanism of macroscopic loosening, bulging, and twisting defects after shaping is mainly due to uneven wall thickness distribution caused by forming. To solve the challenges of shaping thin-walled parts, a rigid shaping method is used to achieve uniform wall thickness. This essentially involves using a fully matched punch and die to rigidly shape the part, minimizing the wall thickness difference in the heat-treated semi-finished product. However, the common problems with these techniques are as follows: First, high-precision matching of the punch and die is required, resulting in high equipment costs; second, the forming and thickness extrusion require extremely high equipment tonnage, which is often insufficient for large-sized parts due to limited equipment table space or tonnage, making it difficult to achieve the desired results. Summary of the Invention

[0005] Purpose of the invention: To provide a pneumatic skin high-energy shaping device and its usage method, which uses the high energy of the explosion to refine the grains of the inner surface material of the semi-finished product under thermal and high pressure, and the inner surface shrinkage offsets the deformation strengthening and solid solution treatment to achieve the purpose of springback; at the same time, the device is energized by magnetic material, and the close contact of the device components provides ultra-high tonnage edge pressing force, overcoming the problem that ultra-large thin-walled parts cannot be mechanically shaped due to the limitations of equipment table size and tonnage.

[0006] In a first aspect, this application provides a pneumatic skin straightening device, which includes a concave mold, a base, a self-locking shaft pin, and a clamping arm;

[0007] The die has a double-step structure. The first step is larger than the second step. Guide holes are provided on the left and right sides of the first step. The lower surface of the second step is an annular pressing surface, which matches the upper surface of the semi-finished flange. The inner side of the annular pressing surface is the effective working surface, which matches the outer surface of the pneumatic skin.

[0008] The base is a rigid flat plate structure. Guide posts matching the guide holes of the die are provided on the left and right sides of the base. Concentric through holes are provided on the positioning bosses on the front and rear sides of the base. Anti-rotation lock groove is provided on one side of the concentric through holes.

[0009] The self-locking pin is matched with the diameter of the concentric through hole of the base. The length of the self-locking pin is greater than the distance between the two sides of the base boss. One end of the self-locking pin is provided with an annular groove, in which an annular ring is suspended. The inner diameter of the annular ring is greater than the diameter of the self-locking pin. The other end of the self-locking pin is provided with an anti-rotation boss, which matches the anti-rotation locking groove of the rigid base.

[0010] The clamping arm has a hook-shaped structure, with a positioning hole at the straight end that matches the diameter of the self-locking pin, and the other end suspended on the top surface of the first step of the die. The self-locking pin passes through the concentric through hole of the clamping arm and the base, fixing the clamping arm on the base. Rotating the clamping arm along the self-locking pin allows for arbitrary interlocking and unlocking of the die and the base.

[0011] Preferably, the top surface of the first step of the die and the free end of the clamping arm are respectively provided with a rectangular avoidance groove and a rectangular boss, the depth of the rectangular avoidance groove being greater than that of the rectangular boss; when the die and the base are in a locked state, the rectangular boss of the clamping arm is embedded in the rectangular avoidance groove of the die; the top surface of the first step of the die is also provided with a number of vent holes connecting the effective working surfaces.

[0012] Preferably, the die and the base are made of magnetic material. The outer side of the second step of the die is provided with an annular groove, and several low-resistance coils are wound in the annular groove. When the coils are connected to a DC power supply, the die is magnetized and pressed onto the base. The upper surface of the base is provided with a profile larger than the lower limit surface of the semi-finished flange edge. The depth of the lower limit surface is equal to the theoretical wall thickness of the pneumatic skin. The matching gap between the outer plane area of ​​the lower limit surface and the annular pressing surface of the die is zero.

[0013] Preferably, the base is further provided with a central hole in the lower limit surface, a U-shaped groove is provided at the bottom edge of the central hole, a battery slot connecting the central hole is provided next to the central hole, and a rigid connecting bridge is installed above the central hole. The connecting bridge is made of non-magnetic material and a magnetic induction switch is fixed on the connecting bridge.

[0014] Preferably, the magnetic induction switch consists of a spring and an I-shaped iron rod; when the current is lower than a specified value, the magnetic induction switch is in a de-energized state, and adjusting the current coil generates a changing magnetic field to preheat the pneumatic skin semi-finished product; when the current is higher than a specified value, the powerfully magnetized die-shaped iron rod descends through magnetic compression of the spring, forming a closed circuit with the battery to release an electric spark; when the coil is in a de-energized state, the base demagnetizing spring returns, and the I-shaped iron rod rising circuit is automatically cut off.

[0015] Secondly, this application also provides a pneumatic skin shaping method, the method comprising:

[0016] Semi-finished product manufacturing: Cut the flange edge of the pneumatic skin semi-finished product according to the outline of the lower limit surface of the base, and then perform solution heat treatment on the cut semi-finished product.

[0017] Correction device and installation and debugging: First, place a small amount of explosive in the center hole of the base. Position the die on the base by the guide hole of the die and the guide post of the base. Rotate the clamping arm inward to make the die and the base automatically interlock. Then, turn the coil to magnetize the die, so that the die presses the base. The magnetic force of the base attracts the I-shaped iron rod to form a closed circuit and releases electric sparks to complete the magnetic induction sensitivity test of the magnetic induction switch.

[0018] Explosion correction: Explosives are placed in the center hole of the base. The semi-finished product is fixed between the concave mold and the base and the flange edge is pressed. Then, the coil is energized to magnetize the concave mold and press the base. At the same time, the magnetic induction switch discharges to detonate the explosives, so that the inner surface material of the semi-finished product is instantly subjected to a thermal high pressure environment to make the grains ultra-fine. The inner surface shrinkage offsets the deformation strengthening and solid solution treatment rebound.

[0019] Pressure holding and unloading: The coil is continuously energized, and the die and base seal the semi-finished product and the heat energy of the explosion, allowing the semi-finished product to cool naturally under high temperature and high pressure and shape preservation. The die is raised by rotating the clamping arm outward, and the semi-finished product is separated from the base.

[0020] Preferably, the magnetic induction test method of the magnetic induction switch is as follows: a small amount of low ignition point explosive is placed between the base and the I-shaped iron rod, the coil current is gradually increased to make the magnetic induction switch close and discharge to ignite the explosive, smoke is observed to be discharged from the exhaust hole of the concave mold, and the extreme current of the coil when the explosive is ignited is recorded.

[0021] Preferably, a lead block is placed in the rectangular avoidance groove on the top surface of the concave mold, and the thickness of the lead block matches the distance between the rectangular boss of the clamping arm and the bottom surface of the rectangular avoidance groove.

[0022] Preferably, a small amount of low-ignition-point explosive is placed in the center of the central hole of the base, and a high-ignition-point explosive is placed in the U-shaped groove of the central hole of the base; before the explosive is detonated, a changing current significantly lower than the explosive detonation limit is passed through the coil to generate a changing magnetic field to preheat the pneumatic skin semi-finished product; when the explosive is detonated, a current significantly greater than the explosive ignition limit is passed through the coil.

[0023] Preferably, the calculation method for the amount of high explosive is: M = 850 * K * V ÷ Q, 1 ≤ k ≤ 2;

[0024] Where M is the mass of the explosive in kilograms; V is the volume of the die in cubic meters; Q is the calorific value of the explosive per unit weight; and K is a coefficient related to the wall thickness, surface area, and shape of the part.

[0025] This application has the following technical effects:

[0026] This application utilizes the high temperature and high pressure of an explosion to impact the surface of the part, which is equivalent to a giant rubber sheet simultaneously striking multiple shaping areas, resulting in significant advantages such as uniform force and large load.

[0027] This application's shaping method utilizes the energy released from a very small amount of explosives to instantly shape the part, avoiding the hardening and cracking defects caused by the solution aging of aluminum alloys. It has significant advantages such as low energy consumption and high speed. This application utilizes the instantaneous high temperature and high pressure environment to facilitate the ultra-fine microstructure of the heated surface material, achieving a microscopic reduction in the inner surface area, which both counteracts unloading springback and improves material performance.

[0028] This application utilizes the immense attraction generated by zero-gap contact of magnetized materials to overcome the limitations of existing equipment in terms of table size and tonnage, which prevents the rapid shaping of large parts. Therefore, the shaping device and method of this application have the advantages of high speed, large force, and uniform force; they are not limited by equipment tonnage, have strong versatility, and are easy to promote; and they can also improve the mechanical properties of the shaped products. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a semi-finished product of a typical pneumatic skin to which this application applies;

[0030] Figure 2 This is a schematic diagram of the assembly structure of the calibration device in this application;

[0031] Figure 3 This is a schematic diagram of the rigid die structure of the forming device of this application;

[0032] Figure 4 This is a schematic diagram of the rigid base structure of the alignment device in this application;

[0033] Figure 5 This is a schematic diagram of the assembly principle of the rigid base and clamping arm of the alignment device in this application;

[0034] Figure 6 This is an enlarged schematic diagram of the working principle of the magnetic induction switch of the calibration device of this application;

[0035] Figure 7This is an enlarged schematic diagram of the self-locking shaft pin and clamping arm assembly of the alignment device of this application;

[0036] Figure 8 This is a schematic diagram of the principle of the cross-section of the correction device in this application;

[0037] The numbers in the diagram are explained as follows: 1. Pneumatic skin, 2. Flange edge, 3. Semi-finished product, 4. Die, 5. Base, 6. Self-locking pin, 7. Clamping arm, 8. First step, 9. Second step, 10. Guide hole, 11. Pressure surface, 12. Working surface, 13. Guide post, 14. Concentric through hole, 15. Anti-rotation lock groove, 16. Annular ring, 17. Anti-rotation boss, 18. Rectangular avoidance groove, 19. Rectangular boss, 20. Vent hole, 21. Annular groove, 22. Coil, 23. Lower limit surface, 24. Center hole, 25. Battery slot, 26. Connecting bridge, 27. Magnetic induction switch, 28. Spring, 29. I-shaped iron rod, 30. Battery, 31. Electric spark, 32. Lead sheet block, 33. Low flash point explosive, 34. High explosive. Detailed Implementation

[0038] It should be noted that this application provides a straightening device and method for solid solution deformation of pneumatic skin, which is particularly suitable for improving the molding accuracy and straightening efficiency of large aluminum alloy skin parts that are difficult to straighten after solid solution under magnetic, thermal and electric field coupling environment.

[0039] See attached document Figure 1 The pneumatic skin 1 is one of the typical objects to which this application applies. The semi-finished pneumatic skin 1 3 is a three-dimensional thin-shell structure with annular flange edges 2 around its perimeter. In order to meet the purpose of forming while improving service strength, complex thin-walled aluminum alloy components are all formed in the annealed state and then subjected to solution heat treatment. However, the correction of deformation caused by solution heat treatment of aluminum alloy is a common problem faced by all sheet metal parts. The existing correction method first uses a rubber plate to quickly beat the area of ​​severe internal stress accumulation in the newly quenched part, and then uses a metal hammer to further make the stress distribution uniform. The problems are as follows: rubber beating or hammering is a region-by-region, point-by-point correction. Defects such as loosening and bulging of thin-walled parts always alternate between different correction intervals, which is inefficient. After solution treatment, aluminum alloy needs to be corrected within the incubation period of maintaining plasticity. If the specified time is exceeded, the difficulty of correction increases exponentially due to age hardening, and even cracking and scrapping may occur. Especially for large and complex thin-walled parts, the material solution incubation period is limited, and relying on experience can easily lead to improper correction, and even the effect of molding will become worse with each correction.

[0040] To address the aforementioned challenges in the solution heat treatment and shaping of large pneumatic skin 1, this application proposes a method that utilizes the enormous energy released during an explosion to simultaneously bombard the inner surface of the semi-finished product 3. This method aims to refine the grains of the inner surface material of the semi-finished product 3 under high-pressure and thermal conditions, thereby achieving the goals of inner surface shrinkage offsetting deformation strengthening and solution treatment rebound. The technical solution of the high-energy shaping device for pneumatic skin in this application is as follows:

[0041] See attached document Figure 2 -Appendix Figure 8 The forming device includes a rigid die 4, a base 5, a self-locking pin 6, and a clamping arm 7. The die 4 has a double-step structure, with the first step 8 being larger than the second step 9. Guide holes 10 are provided on both sides of the first step 8. The lower surface of the second step 9 is an annular pressing surface 11, which is aligned with the upper surface of the semi-finished flange edge 2. The inner side of the annular pressing surface 11 is an effective working surface 12, which matches the outer surface of the pneumatic skin 1. The base 5 has a rigid flat plate structure. Guide posts 13 that match the guide holes 10 of the die are provided on both sides of the base 5. Concentric through holes 14 are provided on the positioning bosses on the front and rear sides of the base. An anti-rotation locking groove 15 is provided on one side of the concentric through hole 14. The self-locking pin 6 matches the diameter of the concentric through hole 14 of the base. The length of the self-locking pin 6 is greater than the distance between the two sides of the boss on the base 5. One end of the self-locking pin 6 has an annular groove, in which an annular ring 16 is suspended. The inner diameter of the annular ring 16 is greater than the diameter of the self-locking pin 6. The other end of the self-locking pin 6 has an anti-rotation boss 17, which matches the anti-rotation locking groove 15 of the rigid base. The clamping arm 7 has a hook-shaped structure. The straight end of the arm has a positioning hole that matches the diameter of the self-locking pin 6, and the other end is suspended on the top surface of the first step 8 of the die. The self-locking pin 6 passes through the clamping arm 7 and the concentric through hole 14 of the base, fixing the clamping arm 7 to the base 5. Rotating the clamping arm 7 along the self-locking pin 6 allows for arbitrary interlocking and unlocking of the die 4 and the base 5. To ensure the safety of the explosion, the main components of the straightening device must meet the requirements of rigidity, interlocking during an explosion, and rapid unlocking and disassembly after straightening.

[0042] See attached document Figure 2 Appendix Figure 3To avoid violent vibrations during an explosion, the clamping arm 7 rotates outward, causing the interlock between the die 4 and the base 5 to fail. The top surface of the first step 8 of the die and the free end of the clamping arm 7 are respectively provided with a rectangular avoidance groove 18 and a rectangular boss 19, with the depth of the rectangular avoidance groove 18 being greater than that of the rectangular boss 19. When the die 4 and the base 5 are locked, the rectangular boss 19 of the clamping arm is embedded in the rectangular avoidance groove 18 of the die. The purpose is that during an explosion, under the action of the guide hole 10 and the guide post 13, the die 4 will only vibrate vertically; upward movement of the die 4 will only tighten the lock further. To prevent heat treatment deformation from causing the semi-finished product 3 to not fit properly with the working surface 12 of the die 4, the top surface of the first step 8 of the die is also provided with several vent holes 20 connecting the effective working surfaces; the purpose is to facilitate the smooth discharge of gas from the non-fitting area.

[0043] See attached document Figure 2 Appendix Figure 3 Appendix Figure 8 To reduce the attenuation of explosion energy, the die 4 and the base 5 are made of magnetic material. An annular groove 21 is provided on the outer side of the second step 9 of the die, and several low-resistance coils 22 are wound within this groove. When the coils 22 are connected to a DC power supply, the die 4 is magnetized and pressed firmly onto the base 5. To maximize the pressing force of the die 4 on the base 5, the upper surface of the base 5 has a profile larger than the lower limit surface 23 of the semi-finished flange edge. The depth of this lower limit surface 23 is equal to the theoretical wall thickness of the pneumatic skin 1, and the matching gap between the outer planar area of ​​the lower limit surface 23 and the annular pressing surface 11 of the die is zero. The purpose is to use the energized coils 22 to magnetize the die 4 and the base 5, and to generate ultra-high pressure edge force through zero-gap contact between the die 4 and the base 5, thereby extending the high-temperature and ultra-high-pressure residence time and improving the shaping and molding effect.

[0044] See attached document Figure 4 Appendix Figure 5 Appendix Figure 8 In order to facilitate the ignition of explosives in a completely sealed state, the base is provided with a central hole 24 in the lower limit surface 23. A U-shaped groove is provided at the bottom edge of the central hole. A battery slot 25 connecting the central hole is provided next to the central hole 24. A rigid connecting bridge 26 is installed above the central hole. The connecting bridge 26 is made of non-magnetic material. A magnetic induction switch 27 is fixed on the connecting bridge. Its purpose is to isolate the detonation switch from the outside world and slow down the energy decay.

[0045] See attached document Figure 4 -Appendix Figure 6To further ensure a completely sealed ignition of the explosive, the magnetic induction switch 27 consists of a spring 28 and an I-shaped iron rod 29. The power supply current connected to the coil 22 is adjustable. When the current is below a specified value, the magnetic induction switch 27 is de-energized. Adjusting the current generates a changing magnetic field that preheats the pneumatic skin semi-finished product 3. When the current is above a specified value, the die 4 strongly magnetizes the I-shaped iron rod 29, causing it to descend through the magnetic compression spring 28, forming a closed circuit with the battery 30 to release an electric spark 31. When the coil 22 is de-energized, the base demagnetizing spring 28 returns to its original position, and the rising circuit of the I-shaped iron rod 29 is automatically cut off. The purpose is to utilize the magnetized magnetic force of the device to ignite the explosive, achieving simultaneous flange edge 2 clamping and explosion, maximizing the utilization rate of explosion energy, reducing the amount of explosive used, and ensuring operational safety.

[0046] See attached document Figure 1 -Appendix Figure 8 The main operating steps and key points of implementation of the calibration device in this application are as follows:

[0047] 1) Semi-finished product manufacturing: Cut the flange edge 2 of the pneumatic skin semi-finished product according to the outline of the lower limit surface 23 of the base, and then perform solution heat treatment on the cut semi-finished product 3.

[0048] 2) Correction device and installation and debugging: First, place a small amount of explosive in the center hole 24 of the base. Position the die 4 on the base 5 using the guide hole 12 of the die and the guide post 13 of the base. Rotate the clamping arm 7 inward to make the die 4 and the base 5 automatically interlock. Then, energize the die 4 by passing the coil 22, so that the die 4 presses the base 5. The magnetic force of the base 5 attracts the I-shaped iron rod 29 to form a closed circuit and release the electric spark 30, thus completing the magnetic induction sensitivity test of the magnetic induction switch 27.

[0049] 3) Explosion correction: Explosives are placed in the center hole 24 of the base. The semi-finished product is fixed between the concave mold 4 and the base 5 and the flange edge 2 is pressed. The coil 22 is energized to magnetize the concave mold 4 and press the base 5. At the same time, the magnetic induction switch 27 discharges to detonate the explosives, so that the inner surface material of the semi-finished product 3 is instantly refined in a hot and high pressure environment. The inner surface shrinks to offset deformation strengthening and solid solution treatment rebound.

[0050] 4) Pressure holding and unloading: Continuously energize the coil 22, and the die 4 and the base 5 seal the semi-finished product 3 and the heat energy of the explosion, so that the semi-finished product 3 cools naturally under high temperature and high pressure and shape preservation. Rotate the clamping arm 7 outward to raise the die 4 and separate the semi-finished product 3 from the base 5.

[0051] See attached document Figure 1 Appendix Figure 3To mitigate the hardening caused by solution treatment and aging of semi-finished product 3, during the manufacturing of semi-finished product 3, the profile of the flange edge 2 of the semi-finished product is at least 5mm smaller than the profile of the lower limit surface 23 of the base. After solution heat treatment and drying, the semi-finished product is rapidly cooled in an environment below -21℃. Reducing the width of the flange edge 2 aims to avoid the impact of solution deformation on positioning, and low-temperature refrigeration aims to delay aging and ensure that the semi-finished product 3 is in its most plastic state during explosion-proofing.

[0052] See attached document Figure 2 Appendix Figure 8 During the installation and debugging of the alignment device, a lead sheet block 31 is placed in the rectangular avoidance groove 18 on the top surface of the concave mold 4. The thickness of the lead sheet block 31 matches the distance between the rectangular boss 19 of the clamping arm and the bottom surface of the rectangular avoidance groove 18. The purpose is to utilize the soft but difficult-to-compress characteristics of lead sheet to buffer the impact of explosion energy on the alignment device.

[0053] See attached document Figure 2 Appendix Figure 8 During the calibration and debugging of the device, the magnetic induction sensitivity test method for the magnetic induction switch 27 is as follows: place low-ignition-point explosive between the base 4 and the I-shaped iron rod 29, gradually increase the current of the coil 22 to close the magnetic induction switch and ignite the explosive, and observe the smoke discharge from the concave mold exhaust hole 20. It should be noted that the purpose of the debugging is to ensure that the device does not detonate the explosive during installation. That is, the spring force of the spring 28 cannot be too small, but the spring force cannot be too large to avoid insufficient magnetic force of the base 5 to form a closed circuit for discharge. Therefore, only a very small amount of explosive needs to be placed, and the coil 22 only needs to be ignited by a small current.

[0054] See attached document Figure 6 Appendix Figure 8 It should be noted that, to ensure the safety of explosive transportation and storage, the greater the explosive power, the higher the ignition point; some high explosives can reach 500 degrees Celsius or even higher. A small amount of low-ignition-point explosive 33 is placed in the center of the base's central hole 24, while high-ignition-point explosive 34 is placed in the U-shaped groove of the base's central hole. Before detonation, a changing current significantly lower than the explosive's detonation limit is passed through the coil 22, causing the coil 22 to generate a changing magnetic field that preheats the pneumatic skin semi-finished product 3. During detonation, a current significantly greater than the explosive's ignition limit is passed through the coil 22. The beneficial effects are as follows: First, it facilitates the smooth ignition of high-ignition-point, high-power explosives, improving operational reliability; second, preheating the semi-finished product helps slow down the cooling rate, improving the shaping and molding effect; third, it facilitates the generation of higher pressure side tonnage in the device, improving the sealing effect and mitigating energy attenuation; and fourth, it minimizes the amount of explosive used, ensuring operational safety.

[0055] To improve the shaping effect while ensuring safety, the amount of explosive must be controlled. The calculation method for the amount of high explosive 34 during explosive shaping is: M = 850 * K * V ÷ Q (recommended 1 ≤ k ≤ 2), where M is the mass of the explosive in kilograms; V is the volume of the die in cubic meters; Q is the calorific value per unit weight of explosive; and K is a correlation coefficient with the part's wall thickness, surface area, and shape. It should be noted that the energy generated by the explosion theoretically causes the air inside the die to heat up to within a short time, not exceeding the solution temperature of the aluminum alloy. Considering that the high temperature and high pressure generated by the explosion are released within an extremely short time (a fraction of a second), the actual ablation of the aluminum alloy material is negligible. Appropriately increasing the amount of explosive can delay the duration of the high temperature and high pressure of the explosion heat, increase the grain refinement ratio of the inner surface material of the semi-finished product 3, and further reduce the inner surface area of ​​the semi-finished product 3 to offset springback.

[0056] In other embodiments of this application, a pneumatic skin high-energy shaping device and its solution-curing method are provided. The die and base of this shaping device have an interlocking function in their natural state. Under coil energization, it provides ultra-high pressure side weight and releases ignition sparks via magnetic force. Explosives are placed inside the shaping device. When the coil is energized, the magnetic force induces a magnetic induction switch to discharge and detonate the explosive, instantly generating high-temperature, ultra-high-pressure gas that impacts the inner surface of the semi-finished product. After the explosion, the coil is continuously energized, and the magnetization between the die and base generates ultra-high pressure side weight, sealing the explosive heat energy and prolonging the high-pressure residence time. This causes thermal compaction of the inner surface material of the semi-finished product, resulting in microscopic shrinkage of the grain area and the formation of surface tension to counteract rebound. The shaping device and method of this application have significant advantages such as high load capacity, low energy consumption, and high speed. They can overcome the problem of poor molding accuracy in large aluminum alloy pneumatic skins due to factors such as solution incubation period, equipment surface area, and tonnage.

Claims

1. A pneumatic skin straightening device, characterized in that, The straightening device includes a concave mold, a base, a self-locking shaft pin, and a clamping arm; The die has a double-step structure. The first step is larger than the second step. Guide holes are provided on the left and right sides of the first step. The lower surface of the second step is an annular pressing surface, which matches the upper surface of the semi-finished flange. The inner side of the annular pressing surface is the effective working surface, which matches the outer surface of the pneumatic skin. The base is a rigid flat plate structure. Guide posts matching the guide holes of the die are provided on the left and right sides of the base. Concentric through holes are provided on the positioning bosses on the front and rear sides of the base. Anti-rotation lock groove is provided on one side of the concentric through holes. The self-locking pin is matched with the diameter of the concentric through hole of the base. The length of the self-locking pin is greater than the distance between the two sides of the base boss. One end of the self-locking pin is provided with an annular groove, in which an annular ring is suspended. The inner diameter of the annular ring is greater than the diameter of the self-locking pin. The other end of the self-locking pin is provided with an anti-rotation boss, which matches the anti-rotation locking groove of the rigid base. The clamping arm has a hook-shaped structure, with a positioning hole at the straight end that matches the diameter of the self-locking pin, and the other end suspended on the top surface of the first step of the die. The self-locking pin passes through the concentric through hole of the clamping arm and the base, fixing the clamping arm on the base. Rotating the clamping arm along the self-locking pin allows for arbitrary interlocking and unlocking of the die and the base.

2. The alignment device as described in claim 1, characterized in that, The top surface of the first step of the die and the free end of the clamping arm are respectively provided with a rectangular avoidance groove and a rectangular boss, the depth of the rectangular avoidance groove being greater than that of the rectangular boss; when the die and the base are locked, the rectangular boss of the clamping arm is embedded in the rectangular avoidance groove of the die; the top surface of the first step of the die is also provided with several vent holes connecting the effective working surfaces.

3. The alignment device as described in claim 2, characterized in that, The die and the base are made of magnetic material. The outer side of the second step of the die has an annular groove, in which several low-resistance coils are wound. When the coils are connected to a DC power supply, the die is magnetized and pressed onto the base. The upper surface of the base has a profile larger than the lower limit surface of the semi-finished flange. The depth of the lower limit surface is equal to the theoretical wall thickness of the pneumatic skin. The matching gap between the outer plane area of ​​the lower limit surface and the annular pressing surface of the die is zero.

4. The alignment device as described in claim 3, characterized in that, The base also has a central hole in the lower limit surface, a U-shaped groove at the bottom edge of the central hole, a battery slot connecting the central hole next to the central hole, and a rigid connecting bridge installed above the central hole. The connecting bridge is made of non-magnetic material and a magnetic induction switch is fixed on the connecting bridge.

5. The alignment device as described in claim 4, characterized in that, The magnetic induction switch consists of a spring and an I-shaped iron rod. When the current is lower than the specified value, the magnetic induction switch is in a de-energized state. Adjusting the current coil generates a changing magnetic field to preheat the pneumatic skin semi-finished product. When the current is higher than the specified value, the powerfully magnetized I-shaped iron rod of the concave mold descends through magnetic compression of the spring, forming a closed circuit with the battery to release an electric spark. When the coil is in a de-energized state, the base demagnetizing spring returns, and the I-shaped iron rod rising circuit is automatically cut off.

6. A pneumatic skin shaping method, characterized in that, The method includes: Semi-finished product manufacturing: Cut the flange edge of the pneumatic skin semi-finished product according to the outline of the lower limit surface of the base, and then perform solution heat treatment on the cut semi-finished product. Correction device and installation and debugging: First, place a small amount of explosive in the center hole of the base. Position the die on the base by the guide hole of the die and the guide post of the base. Rotate the clamping arm inward to make the die and the base automatically interlock. Then, turn the coil to magnetize the die, so that the die presses the base. The magnetic force of the base attracts the I-shaped iron rod to form a closed circuit and releases electric sparks to complete the magnetic induction sensitivity test of the magnetic induction switch. Explosion correction: Explosives are placed in the center hole of the base. The semi-finished product is fixed between the concave mold and the base and the flange edge is pressed. Then, the coil is energized to magnetize the concave mold and press the base. At the same time, the magnetic induction switch discharges to detonate the explosives, so that the inner surface material of the semi-finished product is instantly subjected to a thermal high pressure environment to make the grains ultra-fine. The inner surface shrinkage offsets the deformation strengthening and solid solution treatment rebound. Pressure holding and unloading: The coil is continuously energized, and the die and base seal the semi-finished product and the heat energy of the explosion, allowing the semi-finished product to cool naturally under high temperature and high pressure and shape preservation. The die is raised by rotating the clamping arm outward, and the semi-finished product is separated from the base.

7. The method as described in claim 6, characterized in that, The magnetic induction test method of the magnetic induction switch is as follows: a small amount of low ignition point explosive is placed between the base and the I-shaped iron rod, and the coil current is gradually increased to make the magnetic induction switch close and discharge to ignite the explosive. Smoke is observed to be discharged from the exhaust hole of the concave mold, and the extreme current of the coil when the explosive is ignited is recorded.

8. The method as described in claim 6, characterized in that, A lead block is placed in the rectangular avoidance groove on the top surface of the concave mold, and the thickness of the lead block matches the distance between the rectangular boss of the clamping arm and the bottom surface of the rectangular avoidance groove.

9. The method as described in claim 6, characterized in that, A small amount of low-ignition-point explosive is placed in the center of the central hole of the base, and a high-ignition-point explosive is placed in the U-shaped groove of the central hole of the base. Before the explosive is detonated, a changing current significantly lower than the explosive detonation limit is passed through the coil to generate a changing magnetic field to preheat the pneumatic skin semi-finished product. When the explosive is detonated, a current significantly greater than the explosive ignition limit is passed through the coil.

10. The method as described in claim 9, characterized in that, The calculation method for the amount of high explosive is: M=850*K*V÷Q, 1≤k≤2; Where M is the mass of the explosive in kilograms; V is the volume of the die in cubic meters; Q is the calorific value of the explosive per unit weight; and K is a coefficient related to the wall thickness, surface area, and shape of the part.

Images