Ultra-light tactical back frame based on magnesium-lithium alloy and method of manufacturing thereof

Abstract

The application belongs to the technical field of back frame manufacturing, and discloses an ultralight tactical back frame based on a magnesium-lithium alloy and a manufacturing method thereof. The manufacturing method of the ultralight tactical back frame based on the magnesium-lithium alloy comprises the following steps: extruding or granulating a magnesium-lithium alloy ingot to obtain magnesium-lithium alloy extruded pipes and magnesium-lithium alloy particles; after straightening and post-processing of the magnesium-lithium alloy extruded pipes, ultralight back frame pipes are obtained; after semi-solid die casting forming and reinforcing coating of the magnesium-lithium alloy particles, ultralight back frame joints are obtained; and the ultralight back frame pipes and joints are spliced to obtain the ultralight back frame. The application realizes the demand of the back frame for light weight and high strength, and can be quickly combined and spliced into different geometric sizes according to the service scene, the manufacturing process is simple, the jointing strength is high, the cost is low, and the service life of the ultralight back frame is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of backpack frame manufacturing technology, and particularly relates to an ultralight backpack frame based on magnesium-lithium alloy and its manufacturing method. Background Technology

[0002] The carrying system's heavy-duty frame is the main structural component, serving to provide structural support and transfer load, thereby increasing stability and comfort. Carrying weight is closely related to individual posture control, battlefield awareness, and tactical mobility; a lightweight frame can evenly and effectively distribute the overall weight to the body's load-bearing areas. The quick-release assembly design allows for rapid adjustment of geometry to suit various wartime deployment scenarios, accommodating multi-sized and multi-functional carrying systems.

[0003] Currently, the main materials used in backpack frames include alloy steel, engineering plastics, aluminum alloys, and carbon fiber. Magnesium-lithium alloy, as the world's lightest structural metal material, combines high specific strength and high specific modulus, good damping properties, and shock absorption and noise reduction. Material replacement demonstrates outstanding performance in shock absorption, formability, and functionality. Under the same structure, the backpack frame's weight can be significantly reduced, thereby reducing the burden on the user's joints and muscles and increasing mobility during combat. Due to its good material plasticity, it can act as a buffer when subjected to impact, further protecting the user's safety; due to its good damping properties, it helps reduce the vibration generated by the backpack frame during carrying, reducing the transmission of vibration to the spine and shoulders, and improving carrying comfort.

[0004] Current manufacturing methods for ultralight back frames primarily involve bending followed by welding, or pressure casting. Bending carries a high risk of cracking, is difficult to control, and the thickness of the bending surface inevitably changes during deformation. While literature reports that butt welding of magnesium-lithium alloys can achieve equally strong joints, the spatial structure of the back frame cannot be altered after welding, hindering rapid adaptation in complex battlefield environments. Traditional pressure casting allows for one-piece molding of ultralight back frames, but the high-speed filling technology used in pressure casting makes multi-structure back frames prone to defects such as air entrapment, turbulence, and shrinkage cavities. Furthermore, production cycle time and cost are affected by the pressure casting molds, and the spatial structure cannot be easily modified. These manufacturing technologies fail to meet the requirements of ultralight back frames for lightweight, high-strength, rapid tactical assembly, and low processing costs. Summary of the Invention

[0005] The purpose of this invention is to provide an ultralight tactical back frame based on magnesium-lithium alloy and its manufacturing method, so as to solve the problems of heavy weight, difficult spatial assembly, high cost and insufficient strength of ultralight back frames.

[0006] To achieve this objective, the present invention adopts the following technical solution: A method for manufacturing an ultralight back frame based on magnesium-lithium alloy includes the following steps: S1, Fabrication of ultralight back frame tube, including: S1-1, Magnesium-lithium alloy ingots are extruded to obtain several magnesium-lithium alloy tubular profiles; S1-2, The magnesium-lithium alloy tube profile is straightened to obtain an ultralight back frame pre-profile; S1-3, Post-process the end face of the ultralight back frame pre-profile to obtain the ultralight back frame tube; S2, Fabrication of ultralight back frame joint, including: S2-1, granulation of magnesium-lithium alloy ingots to obtain magnesium-lithium alloy particles. S2-2, The magnesium-lithium alloy particles are semi-solid molded to obtain an ultralight back frame pre-joint. S2-3, reinforce and cover the ultralight back frame pre-joint to obtain the ultralight back frame joint; S3, the ultralight back frame tube and the ultralight back frame connector are spliced ​​together to obtain an ultralight back frame based on magnesium-lithium alloy.

[0007] In some embodiments, the magnesium-lithium alloy ingot refers to an ingot with a lithium content of 8-15 wt% and a density of 1.35-1.55 kg / m³. 3 Magnesium-based alloys.

[0008] In some embodiments, in step S1-1, the magnesium-lithium alloy ingot is preheated before extrusion molding at a temperature of 200-255°C. The extrusion die is a reverse extrusion die with a heating temperature of 295-360°C. The extrusion temperature is 250-295°C, and the extrusion speed is 0.8-1.2 m / min.

[0009] In some embodiments, in steps S1-2, the straightening process uses a straightening mold with a matching concave surface to straighten the magnesium-lithium alloy tube profile.

[0010] It should be noted that the aforementioned correction mold helps to reduce the gap and curvature of the extruded profile, improve the surface flatness of the profile, and facilitate the rapid and smooth assembly of the ultralight tactical back frame.

[0011] In some embodiments, in steps S1-3, the post-processing includes chamfering and smoothing the outer and / or inner sidewalls of the end faces of the ultralight back frame preform to facilitate the splicing of the ultralight back frame tubes.

[0012] In some embodiments, in step S2-1, the granulation process specifically involves: heating the magnesium-lithium alloy ingot to 400-600°C in an inert gas protected furnace, stirring at a speed of 100-300 r / min for 8-14 min to obtain a homogeneous alloy liquid, and injecting it into a high-speed rotating atomizing crucible to break it into homogeneous alloy droplets, which are then cooled by inert gas at a rate of 9-20°C / min to obtain the magnesium-lithium alloy particles.

[0013] In some embodiments, in step S2-2, the semi-solid molding includes heating the magnesium-lithium alloy particles to 400-600°C, stirring the particles at a constant temperature and force of 100-300 r / min for 5-13 min until a semi-solid magnesium-lithium alloy slurry with no macroscopic segregation and uniform structure is obtained, and injecting it into a semi-solid molding die at a temperature of 530-620°C, a screw speed of 100-130 r / min, and a solid fraction maintained at 30-45%.

[0014] In some embodiments, in steps S2-3, the reinforcing coating includes three processes: primer spraying, epoxy prepreg wrapping in an "X" shape, and vacuum curing; before the reinforcing coating, the ultralight back frame pre-joint needs to be acid-washed, degreased, alkali-washed, reverse osmosis water-washed, and vacuum-dried.

[0015] In some embodiments, the primer spraying is performed by mixing the primer and anhydrous ethanol at a volume ratio of 6.5:1.5 and then spraying it using a low-pressure spray gun at 0.3-1.2 MPa.

[0016] An ultralight back frame based on magnesium-lithium alloy is manufactured using the manufacturing method of the ultralight tactical back frame based on magnesium-lithium alloy provided by the present invention.

[0017] The beneficial effects of this invention are: The present invention provides a method for manufacturing an ultralight tactical backpack frame based on magnesium-lithium alloy. Using magnesium-lithium alloy ingots as raw materials, it fulfills the requirements of lightweight and high strength for ultralight backpack frames. Leveraging the excellent damping, shock absorption, and noise reduction properties of magnesium-lithium alloy, it achieves the integrated structural and functional requirements of the ultralight backpack frame, effectively reducing the user's carrying weight and improving tactical mobility and carrying comfort. The magnesium-lithium alloy profile is obtained through extrusion molding and matched with a semi-solid forming joint. Compared to traditional welding or die casting, this method allows for rapid acquisition of the required structure through direct splicing, resulting in lower production costs, higher bonding strength, and fewer internal defects in the material structure. The semi-solid forming joint is coated with a carbon fiber prepreg layer, further improving the load limit, impact resistance, energy absorption performance, and wear resistance of the ultralight backpack frame joint, thus facilitating its adaptation to complex battlefield environments under high loads and extending the service life of the ultralight backpack frame. Attached Figure Description

[0018] Figure 1This is a flowchart of the manufacturing method of an ultralight back frame based on magnesium-lithium alloy provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the magnesium-lithium alloy tubular profile of the ultralight back frame based on magnesium-lithium alloy provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the ultralight back frame based on magnesium-lithium alloy provided in an embodiment of the present invention; Figure 4 This is an exploded structural diagram of the ultralight back frame based on magnesium-lithium alloy provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the sub-plate mounted on the ultralight back frame based on magnesium-lithium alloy provided in an embodiment of the present invention; Figure 6 A schematic diagram of the structure of the T-joint in the ultralight back frame based on magnesium-lithium alloy provided in this embodiment of the invention; Figure 7 A schematic diagram of the four-way connector in an ultralight back frame based on magnesium-lithium alloy provided in this embodiment of the invention.

[0019] In the picture: 1. Back frame unit; 11. Back frame main body; 12. Back frame joint retraction; 2. Connector; 21. T-connector; 22. Four-way connector; 31. Sub-plate; 32. Screws; Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0021] This invention first provides a method for manufacturing an ultralight back frame based on a magnesium-lithium alloy, combined with... Figure 1 The flowchart shown includes the following steps: S1, Fabrication of ultralight back frame tube, including: S1-1, Magnesium-lithium alloy ingots are extruded to obtain magnesium-lithium alloy tubular profiles; S1-2, The magnesium-lithium alloy tube profile is straightened to obtain an ultralight back frame pre-profile; S1-3, Post-process the end face of the ultralight back frame pre-profile to obtain the ultralight back frame tube; S2, Fabrication of ultralight back frame joint, including: S2-1, granulation of magnesium-lithium alloy ingots to obtain magnesium-lithium alloy particles. S2-2, The magnesium-lithium alloy particles are semi-solid molded to obtain an ultralight back frame pre-joint. S2-3, reinforce and cover the ultralight back frame pre-joint to obtain the ultralight back frame joint; S3. The ultralight back frame tube and ultralight back frame connector are spliced ​​together and can be used directly.

[0022] The present invention provides a method for manufacturing an ultralight tactical backpack frame based on magnesium-lithium alloy, which uses magnesium-lithium alloy ingots as raw materials to meet the requirements of lightweight and high strength for ultralight backpack frames. Based on the advantages of magnesium-lithium alloy in terms of good damping, shock absorption and noise reduction, the method achieves the requirement of integrated structure and function of ultralight backpack frames, effectively reducing the user's carrying weight and improving tactical mobility and carrying comfort.

[0023] In the same back frame structure, the present invention uses ultra-light magnesium-lithium alloy as the raw material for the back frame structure, which is about 80.9% lighter than steel, about 44.4% lighter than aluminum alloy, about 16.7% lighter than magnesium alloy, and about 3.2% lighter than carbon fiber.

[0024] This invention uses extrusion molding to obtain magnesium-lithium alloy profiles and matches them with semi-solid forming joints, combining... Figure 3 and Figure 4 As shown, compared to traditional welding or die casting, this method allows for the rapid acquisition of the required structure through direct splicing, resulting in lower production costs, higher bonding strength, and fewer internal defects in the material structure. The splicing joints feature recessed slot structures, combined with a cage-like spatial structure design, ensuring stable splicing of the back frame and preventing the individual components from easily separating.

[0025] Combination Figure 5 As shown, a sub-plate 31 can be added to the back frame structure through splicing and assembly, facilitating space partitioning. Figure 6 , Figure 7 As shown, the semi-solid-formed ultralight back frame joint 2 includes two spatial structures: a three-way joint 21 and a four-way joint 22. By covering it with carbon fiber prepreg layers, the load limit, impact resistance, energy absorption performance and wear resistance of the ultralight back frame joint are further improved, which helps it adapt to the complex battlefield environment with high load and extend the service life of the ultralight back frame.

[0026] In some embodiments, magnesium-lithium alloy ingots refer to ingots with a lithium content of 8-15 wt% and a density of 1.35-1.55 kg / m³. 3 Magnesium-based alloys.

[0027] Specifically, magnesium-lithium alloys can be made of multiple grades, including LA91, LA103, LA113E, and LA141. Using LA91 magnesium-lithium alloy as the back frame material combines the characteristics of being lightweight, high-strength, and having good machinability, resulting in excellent service performance.

[0028] In step S1-1, the magnesium-lithium alloy ingot is preheated before extrusion molding at a temperature of 200-255℃. The extrusion die is a reverse extrusion die. During the extrusion molding process, the heating temperature of the reverse extrusion die is 295-360℃; the extrusion temperature is 250-295℃; and the extrusion speed is 0.8-1.2m / min, which can further improve the finished product quality of the magnesium-lithium alloy profile.

[0029] In the extrusion molding process, magnesium-lithium alloy ingots (including cast bars or ingots) are extruded into profiles (such as those required for producing back frames) through extrusion molding. Figure 2 (As shown). The reverse extrusion die can be used in either cold or hot extrusion mode. When using hot extrusion, the reverse extrusion die is equipped with a controllable heating device, which can adjust the temperature according to the extrusion performance requirements of the profile, to assist in the forming of magnesium-lithium alloy profiles under constant or variable temperature heating conditions. In some embodiments, the magnesium-lithium alloy tube profile can be in the form of a rectangular tube or a round tube.

[0030] In steps S1-2, the straightening process uses a straightening mold with a concave profile. The straightening mold consists of a base plate, a mold handle, an outer fixed mold, a sliding universal mandrel, and anti-displacement baffles. The base plate serves as the foundation of the straightening mold. The outer fixed mold is securely mounted in the center of the base plate, and the mold handle is assembled on the top of the outer fixed mold. The sliding universal mandrel passes through the straightening mold hole of the outer fixed mold. Two anti-displacement baffles are fixed to the base and respectively positioned on the inlet and outlet sides. During straightening, the magnesium-lithium alloy tube profile is inserted into the straightening mold hole, and axial or radial pressure is applied by external force to improve the regularity of the cross-section and axis of the magnesium-lithium alloy tube profile, thereby improving the forming quality and achieving the straightening effect.

[0031] It should be noted that by correcting the mold, the magnesium-lithium alloy tubular profile can reduce the gap and curvature of the extruded profile, improve the surface flatness of the profile, and facilitate the rapid and smooth assembly of the ultralight tactical back frame.

[0032] In some embodiments, steps S1-3 include chamfering and smoothing the outer and / or inner sidewalls of the end faces of the ultralight back frame preform to facilitate the splicing of the ultralight back frame tubes. The post-processing process employs a post-processing fixture with a matching dedicated port, which consists of an inner cutting cylinder and an outer sleeve.

[0033] It should be further explained that the post-processing tooling allows for uniform cutting and chamfering of the end faces and joints of the ultra-lightweight back frame pre-profiles, facilitating rapid assembly and preventing unavoidable surface shapes such as right-angled edges and burrs, or scratches from excess material, from injuring users. Specifically, the joint portion of the ultra-lightweight back frame pre-profile is first shaped using an outer sleeve, creating a recessed section at the joint to improve assembly stability. Then, the outer edge of the ultra-lightweight back frame pre-profile is cut using a chamfering tooling to create a smooth transition at the right-angled interface edge.

[0034] In some embodiments, in step S2-1, the granulation process specifically involves: heating a magnesium-lithium alloy ingot in an inert gas protected furnace to a temperature of 400-600°C until it is completely melted, stirring at a stirring speed of 100-300 r / min for 8-14 min to obtain a homogeneous alloy liquid, and injecting it into a high-speed rotating atomizing crucible to break it into homogeneous alloy droplets, which are then cooled by inert gas at a rate of 9-20°C / min to obtain magnesium-lithium alloy particles.

[0035] In some embodiments, in step S2-2, the semi-solid forming includes: heating magnesium-lithium alloy particles to the melting temperature, and then stirring the particles at a constant temperature and force of 100-300 r / min for 5-13 min until a semi-solid magnesium-lithium alloy slurry with no macroscopic segregation and uniform structure is obtained, and then injecting it into a semi-solid forming mold under the conditions of an injection temperature of 530-620℃, a screw speed of 100-130 r / min, and a solid fraction maintained at 30-45%.

[0036] It should be noted that the core point of failure and damage to the back frame under stress is the joint area. Through a semi-solid forming process, with slow and stable filling, the magnesium-lithium alloy injection liquid is in a laminar flow state, resulting in significantly lower air entrapment compared to traditional pressure casting processes, and superior density.

[0037] In some embodiments, in steps S2-3, the reinforcing coating includes three processes: primer spraying, epoxy prepreg wrapping in an "X" shape, and vacuum curing; before the reinforcing coating, the ultralight back frame pre-joint needs to be acid-washed, degreased, alkali-washed, reverse osmosis water-washed, and vacuum-dried.

[0038] It should be noted that epoxy prepreg application includes reinforcement using unidirectional or bidirectional carbon fiber through overall wrapping or partial winding. For the pre-joint structure of magnesium-lithium alloy ultralight tactical back frame, the reinforcement effect of using unidirectional carbon fiber in an "X" shaped winding is particularly good.

[0039] In some embodiments, the primer spraying is performed by mixing the primer and anhydrous ethanol at a volume ratio of 6.5:1.5 and then spraying it using a low-pressure spray gun at 0.3-1.2 MPa.

[0040] It should be noted that the core point of failure and damage to the back frame under stress is the joint. The ultralight back frame pre-joint is fabricated using a semi-solid molding process. Low-speed, stable filling ensures the magnesium-lithium alloy injection liquid is in a laminar flow state, resulting in significantly lower air entrainment compared to traditional pressure casting processes, and superior density. Coating with carbon fiber further enhances the strength of the ultralight back frame pre-joint, helping to strengthen its performance, disperse stress concentration, and making it particularly suitable for high-load applications.

[0041] It should be noted that, depending on the performance requirements of the magnesium-lithium alloy back frame, the coating thickness of the base adhesive can be selectively set to obtain a stable and high-strength carbon fiber coating layer.

[0042] After the carbon fiber coating is completed, post-processing is required, which includes steps such as grinding and polishing. In the optional scheme, dry grinding is first performed using 100-200 grit sandpaper; then fine grinding is performed step by step using 200-1500 grit sandpaper, in 3-5 levels; finally, polishing is performed using 5-1μm polishing cloth in 1-3 levels, and then wiped or rinsed with organic solvent and blown dry.

[0043] An ultralight back frame based on magnesium-lithium alloy is manufactured using the manufacturing method of the ultralight tactical back frame based on magnesium-lithium alloy provided by the present invention.

[0044] The manufacturing method of the ultralight back frame based on magnesium-lithium alloy provided by this invention produces an ultralight back frame based on magnesium-lithium alloy that has the advantages of being lightweight, high-strength, having good shock absorption and noise reduction, and excellent damping performance. It can also be directly assembled and spliced ​​without cold and hot processing, making the production process simple, low-cost, and conducive to mass production and use in complex battlefield environments.

[0045] like Figures 2-7 As shown, the ultralight back frame based on magnesium-lithium alloy includes several ultralight back frame tubes and several ultralight back frame joints. The ultralight back frame tubes are inserted horizontally and vertically into several ultralight back frame joints, and are assembled into a rectangular frame structure ultralight back frame through plug-in fitting. When the ultralight back frame includes a sub-plate, the sub-plate 31 is connected to the back frame body 11 as a whole by sub-plate screws 32, forming a physical space barrier and also providing the flexibility of disassembly.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing an ultralight back frame based on magnesium-lithium alloy, characterized in that, Includes the following steps: S1, Fabrication of ultralight back frame tube, including: S1-1, Magnesium-lithium alloy ingots are extruded to obtain several magnesium-lithium alloy tubular profiles; S1-2, The magnesium-lithium alloy tube profile is straightened to obtain an ultralight back frame pre-profile; S1-3, Post-process the end face of the ultralight back frame pre-profile to obtain the ultralight back frame tube; S2, Fabrication of ultralight back frame joint, including: S2-1, granulation of magnesium-lithium alloy ingots to obtain magnesium-lithium alloy particles. S2-2, The magnesium-lithium alloy particles are semi-solid molded to obtain an ultralight back frame pre-joint. S2-3, reinforce and cover the ultralight back frame pre-joint to obtain the ultralight back frame joint; S3, the ultralight back frame tube and the ultralight back frame connector are spliced ​​together to obtain an ultralight back frame based on magnesium-lithium alloy.

2. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, The magnesium-lithium alloy ingot refers to one with a lithium content of 8-15 wt% and a density of 1.35-1.55 kg / m³. 3 Magnesium-based alloys.

3. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In step S1-1, the magnesium-lithium alloy ingot is preheated before extrusion molding at a temperature of 200-255°C. The extrusion die is a reverse extrusion die with a heating temperature of 295-360°C. The extrusion temperature is 250-295°C and the extrusion speed is 0.8-1.2 m / min.

4. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In steps S1-2, the straightening process is performed on the magnesium-lithium alloy tube profile by using a straightening mold with a concave surface.

5. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In steps S1-3, the post-processing includes chamfering and smoothing the outer and / or inner sidewalls of the end face of the ultralight back frame preform to facilitate the splicing of the ultralight back frame tubes.

6. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In step S2-1, the granulation process specifically involves heating the magnesium-lithium alloy ingot to 400-600°C in an inert gas protected furnace, stirring it at a speed of 100-300 r / min for 8-14 min to obtain a homogeneous alloy liquid, and then injecting it into a high-speed rotating atomizing crucible to break it into homogeneous alloy droplets. The droplets are then cooled by inert gas at a rate of 9-20°C / min to obtain the magnesium-lithium alloy particles.

7. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In step S2-2, the semi-solid molding includes heating the magnesium-lithium alloy particles to 400-600℃, stirring the magnesium-lithium alloy particles at a constant temperature and force of 100-300 r / min for 5-13 min until a semi-solid magnesium-lithium alloy slurry with no macroscopic segregation and uniform structure is obtained, and injecting it into a semi-solid molding mold at a temperature of 530-620℃, a screw speed of 100-130 r / min, and a solid fraction maintained at 30-45%.

8. The manufacturing method of an ultralight back frame based on magnesium-lithium alloy as described in claim 1, characterized in that, In steps S2-3, the reinforcement coating includes three processes: primer spraying, epoxy prepreg wrapping in an "X" shape, and vacuum curing. Before the reinforcement coating, the ultralight back frame pre-joints need to be acid-washed, degreased, alkali-washed, reverse osmosis water-washed, and vacuum-dried.

9. The method for manufacturing an ultralight back frame based on magnesium-lithium alloy as described in claim 8, characterized in that, The primer spraying is performed by mixing the primer and anhydrous ethanol at a volume ratio of 6.5:1.5, and then spraying it using a low-pressure spray gun at 0.3-1.2 MPa.

10. An ultralight backpack frame based on a magnesium-lithium alloy, characterized in that, It is manufactured using the manufacturing method of the magnesium-lithium alloy-based ultralight back frame according to any one of claims 1-9.

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