Manufacturing clamp and process for titanium alloy front fuselage joint frame of unmanned aerial vehicle

Abstract

The invention discloses a manufacturing clamp and process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle. The manufacturing clamp comprises a base, a pipe base used for fixing a connecting pipe is arranged on the base, and the fixing degree of the connecting pipe can be adjusted through the pipe base; the base is further provided with fixed seats and sliding seats, the fixed seats and the sliding seats are used for containing connectors, each fixed seat and each sliding seat correspond to one connector, the fixed seats are fixedly arranged on the base, the sliding seats can be switched between the state of being fixedly arranged on the base or the state of being arranged on the base in a sliding mode, and the fixed seats and the sliding seats are provided with downward pressing assemblies. When stress is removed after welding, fixed constraint of the sliding seat and the base is detached, so that the sliding seat can freely slide in the length direction, fixation of the pipe seat and the connecting pipe is released, and a tiny movable gap is reserved between the pipe seat and the connecting pipe; the whole device is put into a vacuum furnace, the part is heated along with the furnace, the part expands in the heating process of heat treatment and drives the sliding seat to move, and meanwhile the connecting pipe extends in the pipe seat; the cooling is contrary.

Description

Technical Field

[0001] The invention relates to a manufacturing fixture and process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle (UAV), belonging to the technical field of mechanical processing. Background Art

[0002] In the field of drone manufacturing, both military and civilian drones have experienced rapid development since the 2020s. Aircraft fuselage load-bearing components often utilize titanium alloy frames and beams to ensure both lightweight and strength. This joint assembly, a key component connecting the composite front fuselage and the metal mid-fuselage structure, consists of two symmetrical pieces welded from TA2 titanium tubes and machined parts, with specific external dimensions.

[0003] However, there are many difficulties in its manufacturing: titanium alloys easily absorb hydrogen at 400°C and above, and over-temperature welding and heat treatment will cause the hydrogen content to increase, causing hydrogen embrittlement and product failure; the product structure has poor rigidity, and processing stress can easily cause deformation, making it difficult to ensure size; TA2 post-weld stress relief annealing requires a 480-750°C vacuum environment, and the cost of using high-temperature alloys and titanium alloys for heat treatment tooling is high. If 304 stainless steel is used, the linear expansion coefficient is large different from TA2, and traditional tooling is prone to pulling the parts in the length direction of deformation during heating and cooling. These difficulties restrict the reliable manufacturing of the joint assembly and urgently need targeted technological breakthroughs. Summary of the Invention

[0004] The purpose of the present invention is to provide a manufacturing fixture and process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle in response to the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: a manufacturing fixture for a titanium alloy front fuselage joint frame of a UAV, wherein the titanium alloy front fuselage joint frame of the UAV comprises a connecting pipe, wherein the outer wall of the connecting pipe is connected to a plurality of joints along the axial direction; The manufacturing fixture includes a base, on which is provided a tube seat for fixing the connecting tube, and the tube seat can adjust the degree of fixation of the connecting tube; the base is also provided with a fixed seat and a sliding seat for placing the joint, each of the fixed seat and the sliding seat corresponds to a joint respectively, the fixed seat is fixedly set on the base, and the sliding seat can be switched between a fixed or sliding state on the base, and the fixed seat and the sliding seat have a downward pressing component.

[0006] Optionally, the pipe seat includes a support platform, which is fixed on the base. A clamp is provided on the support platform, and the clamp fixes the connecting pipe to the support platform.

[0007] Optionally, two limit columns are further provided on the base, and the two limit columns are respectively inserted into the two ends of the connecting pipe. A limit step is provided on the side of the limit column facing the connecting pipe, one of the limit columns is fixed on the base through a connecting piece, and the other limit column is provided on the base through a pipe seat.

[0008] Optionally, a slot is provided on the base, and a plug is provided at the bottom of the sliding seat. The length of the slot along the axial direction of the connecting tube is greater than the length of the plug. The plug is arranged in the slot, and a fixed block is also inserted between the plug and the slot in the length direction.

[0009] Optionally, the fixing block is in an inverted L-shape, the upper portion of the fixing block is located on the base via support bolts, and the bottom of the fixing block is wedge-shaped.

[0010] Optionally, both the fixed seat and the sliding seat have a placement table for placing the joint, and a pressure block for pressing the joint is provided above the placement table. The pressure block is fixed to the base through a first pressing component; or fixed to the placement table through a second pressing component.

[0011] A manufacturing process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle, comprising: When welding, fix the sliding seat on the base, fix the connecting pipe on the pipe seat, fix the joint on the fixed seat and the sliding seat respectively, and adjust the relative position of the connecting pipe and the joint; When relieving stress after welding, remove the fixed constraints of the sliding seat and the base so that the sliding seat can slide freely along the length direction, and loosen the fixation of the tube seat and the connecting pipe to maintain a small movable gap between it and the connecting pipe; put the entire device into a vacuum furnace, and the parts will heat up with the furnace. During the heat treatment heating process, the parts will expand, driving the sliding seat to move, and at the same time the connecting pipe will extend on the tube seat; the opposite will happen when the temperature is lowered.

[0012] Optionally, during welding, a first pressing assembly is used to fix the joint and the sliding seat to the base; during stress relief after welding, a second pressing assembly is used to fix the joint to the sliding seat.

[0013] Alternatively, a manufacturing process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle comprises the following stages: Pickling: Pickle the prefabricated connecting pipes and all joints separately to thoroughly remove surface oxides and contaminants; Dehydrogenation: After pickling, the connecting pipes and all joints are subjected to dehydrogenation treatment respectively, placed in a special oven, and heated and kept warm according to regulations to remove the hydrogen elements that may be introduced during the pickling process; Assembly: Fix the sliding seat on the base, fix the connecting pipe on the pipe seat, fix the joint on the fixed seat and sliding seat respectively, and adjust the relative position of the connecting pipe and joint; Position welding: After confirming that the positions of all components are adjusted correctly, perform symmetrical and uniform spot welding in the circumferential direction of the connecting pipe and each joint to initially fix the connecting pipe and each joint together; Argon arc welding: After completing the positioning welding, continuous argon arc welding is performed along the entire circumferential seam where the connecting pipe and each joint are connected, so that the connecting pipe and each joint are completely welded into an integral frame structure; Fitter: After welding is completed, perform fitter finishing; Post-weld stress relief: Remove the fixed constraints of the sliding seat and the base to allow the sliding seat to slide freely along the length direction, and loosen the fixation of the support platform and the connecting pipe to leave a small movable gap between it and the connecting pipe; put the entire device into a vacuum furnace, and the parts will heat up with the furnace. During the heat treatment process, the parts will expand, driving the sliding seat to move, and at the same time the connecting pipe will extend on the pipe seat; the opposite will happen when the temperature is lowered; Cleaning: After the heat treatment is completed, wait for the parts to cool to a safe operating temperature and remove them from the heat treatment tooling; perform a final cleaning on the removed frame parts to thoroughly remove any oil and dust that may have remained during the heat treatment process.

[0014] Optionally, when removing hydrogen, heat up to 120-150℃ in stages and keep warm for 60-120min; hydrogen content test is carried out on the accompanying test piece (when the pickling thickness is 0.025 on each side, the amount of hydrogen added shall not exceed 0.003%; When welding, use dust-free paper or white silk cloth dipped in alcohol or acetone to wipe the area to be welded until there is no dirt, and do a good job of gas protection on the back or inside the tube; When tack welding, use argon arc welding to evenly weld 4-8 points around the joint and the connecting pipe on the tooling; When stress relieving, the vacuum pressure of the vacuum chamber should be evacuated to no more than 6.7×10-2Pa before heating the parts; the parts are heated with the furnace, and the timing starts when the control instrument reaches the set temperature of 580℃, and the holding time is 60-90 minutes; after the holding period, the parts are cooled with the furnace to ≤400±10℃, and then cooled to ≤100℃ by 2bar argon gas, and then air-cooled after being taken out of the furnace.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention provides a manufacturing fixture and process for the titanium alloy front fuselage joint frame of an unmanned aerial vehicle, which provides rigid constraints during welding to ensure component assembly accuracy and welding stability. During the stress relief stage after welding, the sliding seat slides freely, and the tube seat retains a movable gap. This allows the parts to deform freely with thermal expansion and contraction during heat treatment, effectively releasing residual stress and solving the deformation problem caused by tooling constraints.

[0016] 2. The present invention provides a manufacturing process for the titanium alloy front fuselage joint frame of a UAV. Pickling and staged dehydrogenation treatments effectively remove surface impurities and hydrogen elements, strictly control the amount of hydrogen addition, and reduce the risk of hydrogen embrittlement of titanium alloys from the source. The process of deep cleaning and gas protection before welding, positioning welding and argon arc welding are combined to ensure the quality of the weld and reduce defects such as porosity and oxidation. In the heat treatment process, high vacuum environment control and precise heating, insulation and cooling systems avoid oxidation of titanium alloys while ensuring that stress is fully released and no secondary stress is generated. The entire technical solution systematically solves the core problems of hydrogen embrittlement, deformation, tooling adaptation, etc. in the manufacture of titanium alloy joint frames, improves product dimensional accuracy and mechanical properties, reduces production costs, meets the high-quality manufacturing needs of UAVs, and has significant engineering application value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The diagram is a structural diagram of a manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV.

[0018] Figure 2 It is a structural diagram of the titanium alloy front fuselage joint frame of the UAV.

[0019] Figure 3 It is a schematic diagram of the connection between the base and the sliding seat.

[0020] Figure 4 It is a schematic diagram of the connection between the sliding seat and the base.

[0021] Figure 5 It is a schematic diagram of the first clamping assembly fixing the sliding seat.

[0022] Figure 6 It is a schematic diagram of the second pressing assembly fixing the sliding seat.

[0023] Figure 7 This is a schematic diagram of the titanium alloy front fuselage joint frame of the UAV and its manufacturing fixture.

[0024] Markings in the figure: 1-base, 101-slot, 2-tube seat, 201-support platform, 202-clamp, 3-fixed seat, 4-sliding seat, 401-insert block, 402-placement table, 5-downward pressure assembly, 501-pressure block, 502-first clamping assembly, 503-second clamping assembly, 6-limiting column, 7-connecting piece, 8-fixed block. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings.

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] A manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV, such as Figure 1-7 As shown, the titanium alloy front fuselage joint frame of the UAV includes a connecting pipe, and the outer wall of the connecting pipe is axially connected with a plurality of joints; The manufacturing fixture includes a base 1, on which is provided a tube seat 2 for fixing the connecting pipe, and the tube seat 2 can adjust the degree of fixation of the connecting pipe; the base 1 is also provided with a fixed seat 3 and a sliding seat 4 for placing the joint, each of the fixed seat 3 and the sliding seat 4 corresponds to a joint, the fixed seat 3 is fixedly set on the base 1, and the sliding seat 4 can be switched between a fixed or sliding state on the base 1, and the fixed seat 3 and the sliding seat 4 have a pressing component 5.

[0028] The pipe seat 2 is used to securely clamp the connecting pipe during the processing phase by adjusting the degree of fixation to ensure processing accuracy. Secondly, during stress relief after welding, the fixation is loosened, leaving a small gap to provide room for the connecting pipe to expand and contract due to heat and cold, thereby avoiding deformation due to tooling constraints and the generation of additional stress. During welding and conventional processing, the fixed seat 3 secures and supports the corresponding joint, while the press-down assembly 5 cooperates to constrain the joint from above to prevent displacement and deformation during processing. During heat treatment, it serves as an anchor point and cooperates with the slidable sliding seat 4 to adapt to overall thermal deformation of the workpiece. The sliding seat 4 can be switched to a fixed state during the processing phase to assist in constraining the joint. During stress relief after welding, the fixed constraint with the base 1 is released, and the workpiece slides along the length direction as it expands thermally, releasing thermal stress and avoiding stress concentration caused by deformation of the workpiece due to tooling constraints. Whether it is the fixed seat 3 or the sliding seat 4, the press-down assembly 5 constrains the joint in the vertical direction to prevent the joint from detaching from the tooling due to vibration, thermal deformation, etc. during processing and heat treatment, ensuring the stability of the relative position of the joint and the connecting pipe. During machining, multi-dimensional constraints are applied to the tube holder 2, fixed seat 3, sliding seat 4, and press-down assembly 5 to control deformation caused by welding and machining stress. During heat treatment, the gap between the tube holder 2 and the sliding design of the sliding seat 4 allow the flexible structure to freely adjust with thermal expansion and contraction of the workpiece, reducing the forced stress caused by the thermal expansion difference between the tooling and the workpiece, and ensuring dimensional accuracy. A set of fixtures covers multiple processes, simplifying the process and reducing costs. Abandoning the idea of ​​relying on special materials to match thermal expansion, the structural design allows conventional tooling to adapt to TA2 titanium alloy heat treatment, solving the problem of linear expansion differences in 304 stainless steel tooling, while avoiding dependence on high-cost materials such as high-temperature alloys, and balancing economy and reliability.

[0029] As another specific embodiment, the tube base 2 includes a support platform 201, which is fixedly mounted on the base 1. A clamp 202 is provided on the support platform 201, which secures the connecting tube to the support platform 201. The support platform 201 is fixed to the base 1, providing a rigid support surface for the connecting tube, ensuring a stable support at the bottom during processing, and preventing uneven stress on the connecting tube itself due to suspension or unstable support, which could cause deformation. During welding, in particular, the clamp 202 can transmit and disperse welding thermal stress, reducing the risk of localized stress concentration. Compared to rigid clamping methods, the clamp 202 provides sufficient clamping force to ensure stable processing while also buffering the stress impact generated during processing to a certain extent. Furthermore, during post-weld stress relief heat treatment, loosening the clamp 202 can quickly release the strong constraint on the connecting tube. Combined with the slight clearance retained by the support platform 201, this allows the connecting tube to expand and contract more freely, further relieving thermal stress. During the machining phase, the support platform 201 and clamp 202 provide a stable restraint on the connecting pipe, ensuring welding and machining accuracy. During the heat treatment phase, the clamp 202 quickly releases, allowing the connecting pipe to move slightly on the support platform 201 to accommodate thermal deformation. This single structure covers multiple process steps, simplifies fixture switching, and improves production efficiency.

[0030] As another specific embodiment, two limiting columns 6 are further provided on the base 1, and the two limiting columns 6 are respectively inserted into the two ends of the connecting pipe. A limiting step is provided on the side of the limiting column 6 facing the connecting pipe, one of the limiting columns 6 is fixedly provided on the base 1 through a connector 7, and the other limiting column 6 is provided on the base 1 through a pipe seat 2. The limiting columns 6 are inserted into the two ends of the connecting pipe, and the limiting step cooperates with the port of the connecting pipe to form an axial position, accurately limiting the axial position of the connecting pipe on the base 1, avoiding axial movement of the connecting pipe due to force during processing, and ensuring the axial dimensional accuracy of the welding and assembly of the joint and the connecting pipe. The fixed end limiting column 6 serves as an axial anchor point, providing an absolutely fixed axial reference, ensuring the stable position of one end of the connecting pipe, providing a reliable positioning reference for welding and assembly, ensuring the consistency of the relative position of the joint and the connecting pipe, and serving as a reference end in the process to control the overall dimensional chain. The stoppers 6 at the ends of the tube sockets 2 flexibly fit within the tube sockets 2, ensuring support and positioning of the connecting tubes during the machining phase. During the heat treatment phase, as the tube sockets 2 adjust their flexibility, the stoppers 6 adapt to longitudinal deformation of the connecting tubes, preventing the concentration of tensile and compressive stresses in the connecting tubes caused by rigid fixation at both ends and further relieving thermal deformation stresses. Precise axial positioning by the stopper steps and radial support by the columns control deformation of the connecting tubes during machining and heat treatment from multiple dimensions, enhancing dimensional accuracy. In another specific embodiment, the base 1 is provided with a slot 101, and the bottom of the sliding seat 4 has an insert 401. The length of the slot 101 along the axial direction of the connecting tube is greater than the length of the insert 401. The insert 401 is positioned within the slot 101, and a fixing block 8 is interposed between the insert 401 and the slot 101 along its length. The slot 101 provides guidance and a mounting base for the sliding seat 4, limiting its axial movement along the connecting tube and ensuring that it can only slide along a predetermined trajectory. This prevents the sliding seat 4 from drifting or becoming stuck during heat treatment, and ensures stable release of thermal deformation. The insert 401 engages the slot 101 to provide initial positioning of the sliding seat 4 and simultaneously communicates the relative position between the sliding seat 4 and the base 1. During the machining phase, the fixed block 8 is inserted into the gap between the insert block 401 and the slot 101, filling the axial space and locking the sliding seat 4 within the slot 101. This, in conjunction with the fixed seat 3, provides a stable and rigid constraint for the joint, ensuring machining accuracy. During the heat treatment phase, the fixed block 8 is removed, releasing the axial constraint between the slot 101 and the insert block 401, allowing the sliding seat 4 to slide freely along the slot 101 to accommodate the thermal expansion of the workpiece. This simple operation and high reliability reduce equipment costs and maintenance difficulties.

[0031] As another specific embodiment, the fixed block 8 is in an inverted L-shape, with the upper portion of the fixed block 8 positioned on the base 1 via support bolts, and the bottom portion of the fixed block 8 being wedge-shaped. The horizontal arm of the fixed block 8 is fixed to the base 1 via support bolts, forming a stable fulcrum and providing a vertical mounting foundation for the fixed block 8. The bottom portion of the lower vertical arm is designed to be wedge-shaped and inserted into the gap between the slot 101 and the insert block 401 to achieve axial constraint on the sliding seat 4. When the wedge-shaped inclined surface is inserted into the gap between the insert block 401 and the slot 101, as the insertion depth increases, the inclined surface will generate a horizontal thrust on the insert block 401, causing the insert block 401 to fit tightly against the inner wall of the slot 101, forming a self-locking effect, preventing the fixed block 8 from loosening due to vibration, welding thermal stress, etc. during processing, and ensuring the rigid fixation of the sliding seat 4.

[0032] As another specific embodiment, both the fixed seat 3 and the sliding seat 4 have a placement table 402 for placing the joint, and a pressure block 501 for pressing the joint is provided above the placement table 402, and the pressure block 501 is fixed to the base 1 through a first pressing component 502; or fixed to the placement table 402 through a second pressing component 503. The placement table 402 provides a horizontal support surface for the joint to ensure the accuracy of the relative position of the joint and the connecting pipe before welding. The pressure block 501 covers the top of the joint and evenly transfers the pressing force to the joint surface, and cooperates with the placement table 402 to form upper and lower constraints to prevent the joint from warping or vibration displacement due to thermal stress during welding, and at the same time limits the relative displacement of the joint and the sliding seat 4 during heat treatment to ensure consistency of thermal deformation. In the welding mode, the first pressing component 502 is rigidly fixed, and the pressing force is transmitted to the entire fixture system through the base 1 to avoid local deformation caused by the sliding seat 4 bearing the welding stress alone. During post-weld stress relief, the pressing block 501 is secured to the placement platform 402 via a second assembly. As the part expands with furnace temperature, the sliding seat 4 drives the placement platform 402 and the pressing block 501 to slide axially. This creates a dynamic constraint between the pressing block 501 and the joint, limiting joint warping and deformation while allowing it to move freely with the sliding seat 4, thus avoiding the thermal stress concentration caused by traditional rigid clamping. The pressing block 501, first clamping assembly 502, and second clamping assembly 503 together constitute the lower-holding assembly 5.

[0033] A manufacturing process for a titanium alloy front fuselage joint frame of an unmanned aerial vehicle, comprising: During welding, secure the sliding seat 4 to the base 1, the connecting tube to the tube seat 2, and the joints to the fixed seat 3 and sliding seat 4, respectively. Adjust the relative positions of the connecting tubes and joints. Securely attach the sliding seat 4 to the base 1 to ensure it remains stable during welding. Secure the connecting tubes securely to the tube seat 2, providing a reference for subsequent assembly. Secure the joints to the fixed seat 3 and sliding seat 4, respectively, to ensure the relative positional accuracy of the joints and connecting tubes. On this basis, fine-tune the positions of the connecting tubes and joints to ensure their assembly relationship meets design requirements, laying the foundation for high-quality welding and guaranteeing weld strength and dimensional accuracy.

[0034] To relieve stress after welding, the constraints between the sliding seat 4 and the base 1 are removed, allowing the sliding seat 4 to slide freely along its length. The tube base 2 is then loosened from its attachment to the connecting tube, leaving a slight clearance between the two. The entire assembly is then placed in a vacuum furnace, where the component heats up. During the heat treatment process, the component expands, driving the sliding seat 4 to move, while the connecting tube extends within the tube base 2. The reverse occurs during cooling. To avoid new stresses caused by tooling constraints during the heat treatment process, the fixture must be adjusted. First, the constraints between the sliding seat 4 and the base 1 are removed, allowing the sliding seat 4 to slide freely along the length of the connecting tube. Next, the tube base 2 is loosened from its attachment to the connecting tube, leaving a slight clearance between the connecting tube and the tube base 2. After these adjustments are complete, the entire assembly is placed in a vacuum furnace, where the component heats up slowly. During this heating process, the titanium alloy component expands, driving the sliding seat 4 axially. The connecting tube also extends within the tube base 2, effectively relieving the stresses generated by thermal expansion. During the cooling process, the parts shrink, and the sliding seat 4 and the connecting pipe are reset accordingly. This process effectively eliminates welding residual stress and improves product performance and dimensional stability.

[0035] As another specific embodiment, during welding, a first clamping assembly 502 is used to secure the joint and the sliding seat 4 to the base 1. During post-weld stress relief, a second clamping assembly 503 is used to secure the joint to the sliding seat 4. During the welding process, the first clamping assembly 502 is used to achieve a stable connection. The first clamping assembly 502 is mounted on the base 1, applying pressure to the joint on the fixed seat 3 and the sliding seat 4, tightly securing the joint and the sliding seat 4 to the base 1. This rigid connection effectively resists the thermal and mechanical stresses generated during welding, preventing displacement or deformation of the joint and the sliding seat 4. This ensures the accuracy of the relative positions of the components during welding, thereby improving welding quality and reducing welding defects caused by positional deviation. During the post-weld stress relief process, the second clamping assembly 503 must be switched. After removing the first clamping assembly 502, the second clamping assembly 503 is mounted on the placement table 402, securing the joint to the sliding seat 4. Compared to the rigid fixation provided by the first clamping assembly 502, the second clamping assembly 503 provides a more flexible constraint. When the entire device enters the vacuum furnace for heat treatment, as the parts heat up and expand, the sliding seat 4 can move freely, driving the joint to move together. The second clamping assembly 503 allows the joint and the sliding seat 4 to remain relatively fixed while freely changing in the length direction with the sliding seat 4, ensuring that the stress of the parts can be fully released during the process of thermal expansion and contraction, avoiding new stress caused by excessive constraints of the tooling, and effectively ensuring the product dimensional accuracy and performance stability.

[0036] As another specific implementation method, the following stages are included: Pickling: Pickle the prefabricated connecting pipes and all joints to thoroughly remove surface oxides and contaminants. This process primarily targets the prefabricated connecting pipes and all joints, effectively removing surface oxides and contaminants. Failure to remove these impurities can affect subsequent welding quality and even degrade material performance. Pickling provides a clean foundation for subsequent processes.

[0037] Hydrogen Removal: After pickling, the connecting pipes and all joints are subjected to a dehydrogenation treatment. They are placed in a dedicated oven and heated and insulated according to established procedures to remove any hydrogen that may have been introduced during the pickling process. Because the pickling process can allow hydrogen to penetrate the material and create a risk of hydrogen embrittlement for titanium alloys, the connecting pipes and joints are placed in a dedicated oven and heated and insulated according to established procedures. This step fully removes any adsorbed hydrogen from the material, reducing the risk of hydrogen embrittlement and ensuring product safety.

[0038] Assembly: Secure the sliding base 4 to the base 1, the connecting pipe to the pipe base 2, and the connectors to the fixed base 3 and sliding base 4, respectively. Adjust the relative positions of the connecting pipes and connectors. First, secure the sliding base 4 firmly to the base 1, precisely secure the connecting pipe to the pipe base 2, and secure the connectors to the fixed base 3 and sliding base 4, respectively. Next, finely adjust the relative positions of the connecting pipes and connectors to ensure assembly accuracy between components and provide optimal conditions for welding.

[0039] Tack Welding: After confirming that all components are correctly positioned, perform symmetrical and even spot welding around the circumference of the connecting pipe and each joint to initially secure them together. After confirming that the components are correctly positioned, perform symmetrical and even spot welding around the circumference of the connecting pipe and joint. This initial fixation of the connecting pipe and joint not only stabilizes the relative positions of the components but also distributes welding stress to a certain extent, providing a stable foundation for subsequent welding.

[0040] Argon arc welding: After tack welding, continuous argon arc welding is performed along the entire circumference of the joints connecting the pipe and each joint, completely welding the pipe and joints into a single, integrated framework. Continuous welding is performed along the entire circumference of the joints connecting the pipe and joints. The process characteristics of argon arc welding ensure a stable welding process, completely integrating the pipes and joints into a single, integrated framework, and guaranteeing weld strength and sealing.

[0041] Benchwork: After welding is completed, benchwork is performed. Benchwork can correct the welded frame manually or with the help of tools, remove excess weld bumps and burrs, and smooth out uneven areas to make the appearance and size of the frame more in line with the design requirements.

[0042] Post-weld stress relief: Remove the fixed constraints of the sliding seat 4 and the base 1, allowing the sliding seat 4 to slide freely along the length direction, and loosen the fixation of the support platform 201 to the connecting tube, so that a small movable gap is left between the sliding seat 4 and the connecting tube; place the entire device in a vacuum furnace, and the parts will heat up with the furnace. During the heat treatment, the parts will expand, driving the sliding seat 4 to move, and at the same time, the connecting tube will extend in the tube base 2; the opposite will happen when the temperature is lowered. First, release the fixed constraints of the sliding seat 4 and the base 1, loosen the fixation of the supporting platform 201 on the connecting tube, and leave a small movable gap. Then place the entire device in a vacuum furnace, and the parts will expand with the furnace, driving the sliding seat 4 to move, and the connecting tube will extend in the tube base 2; when the temperature is lowered, the parts will shrink and reset. This process effectively releases welding residual stress and improves the dimensional stability and mechanical properties of the frame.

[0043] Cleaning: After heat treatment is complete, wait for the components to cool to a safe operating temperature and remove them from the heat treatment fixture. The removed frame components undergo a final cleaning to thoroughly remove any oil and dust that may have remained during the heat treatment process. As the final step, wait for the heat-treated components to cool to a safe temperature and remove them from the fixture. This thorough cleaning of the frame components removes any impurities such as oil, dust, and other impurities left during the heat treatment process, ensuring the frame is clean enough for assembly and use.

[0044] As another specific implementation method, when removing hydrogen, the temperature is raised to 120-150°C in stages and kept warm for 60-120 minutes; the hydrogen content is tested on the test pieces accompanying the furnace (when the pickling thickness reaches 0.025 on each side, the hydrogen increase shall not exceed 0.003%. A staged heating strategy is adopted, gradually raising the temperature to 120-150°C and keeping it in this temperature range for 60-120 minutes. The stepped heating method avoids the internal stress of the material caused by sudden temperature changes, and the long-term heat preservation ensures that the hydrogen element fully diffuses and escapes. At the same time, the test pieces are placed in the furnace for accurate testing of the hydrogen content. When the pickling thickness reaches 0.025 on each side, the hydrogen increase shall be strictly controlled not to exceed 0.003%, eliminating the hidden danger of hydrogen embrittlement at the source and ensuring the stable performance of the titanium alloy material.

[0045] During welding, wipe the area to be welded with dust-free paper or white silk cloth dipped in alcohol or acetone until it is free of dirt. Ensure that gas shielding is applied to the back or inside the pipe. Use dust-free paper or white silk cloth dipped in an organic solvent such as alcohol or acetone to repeatedly wipe the connecting pipe and joint to be welded until the surface is free of oil and impurities. Furthermore, to prevent metal oxidation during welding, ensure gas shielding is applied to the back or inside the pipe. High-purity argon is introduced to form an inert gas barrier to ensure weld quality and avoid defects such as porosity and oxidation.

[0046] During tack welding, argon arc welding is performed on the fixture to evenly weld the joint and connecting pipe at 4-8 tack points along the circumference. The components are precisely secured on a dedicated fixture. Using argon arc welding, 4-8 tack welds are evenly welded around the circumference of the joint and connecting pipe. The number and distribution of tack welds are optimized to quickly secure the relative position of the components while distributing welding stress and preventing localized deformation. The welds must be well-fused and uniform in size to provide a stable foundation for subsequent continuous welding.

[0047] To relieve stress, the vacuum chamber pressure is reduced to no more than 6.7×10-2Pa before heating the part. The part is heated in the furnace, and the timer begins when the control instrument reaches the set temperature of 580°C. The holding time is 60-90 minutes. After the holding period, the part is cooled in the furnace to ≤400±10°C, then cooled to ≤100°C with 2 bar of argon gas. The part is then removed from the furnace and air-cooled. Before entering the furnace, the vacuum chamber pressure is reduced to no more than 6.7×10⁻²Pa to create a high vacuum, oxygen-free environment to prevent high-temperature oxidation of the titanium alloy. The part is heated slowly in the furnace, and the timer begins when the control instrument displays the set temperature of 580°C. The part is then held at this temperature for 60-90 minutes to fully release residual stress. After the holding period, the part is first cooled in the furnace to 400±10°C, then forced to cool to below 100°C with 2 bar of argon gas. The part is then removed from the furnace and air-cooled. This staged cooling effectively avoids the generation of secondary stresses caused by large temperature differences, ensuring that the frame meets dimensional accuracy and mechanical performance standards.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The present invention extends to any new features or any new combinations disclosed in this specification, and any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the detailed technical features not disclosed in this embodiment, such as the specific structure, are all prior art, and those skilled in the art can obtain them from the prior art; the connection method can be a fixed connection, a detachable connection, or an integrated connection; it can be a fixed connection, a movable connection or a hinged connection, and can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific manner of the above terms in the embodiments of the present invention can be understood according to the specific circumstances, and the embodiments disclosed herein do not make specific limitations on this.

Claims

1. A fixture for manufacturing a titanium alloy front fuselage joint frame for a drone, the titanium alloy front fuselage joint frame comprising a connecting tube, the outer wall of which is axially connected to a plurality of joints; characterized in that: The manufacturing fixture includes a base, on which is provided a tube seat for fixing the connecting tube, and the tube seat can adjust the degree of fixation of the connecting tube; the base is also provided with a fixed seat and a sliding seat for placing the joint, each of the fixed seat and the sliding seat corresponds to a joint respectively, the fixed seat is fixedly set on the base, and the sliding seat can be switched between a fixed or sliding state on the base, and the fixed seat and the sliding seat have a downward pressing component.

2. The manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV as claimed in claim 1, characterized in that: The pipe seat includes a support platform, which is fixed on the base. A clamp is provided on the support platform, and the clamp fixes the connecting pipe on the support platform.

3. The manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV as claimed in claim 1, characterized in that: The base is also provided with two limit columns, which are respectively inserted into the two ends of the connecting pipe. A limit step is provided on the side of the limit column facing the connecting pipe. One of the limit columns is fixed on the base through a connecting piece, and the other limit column is provided on the base through a pipe seat.

4. The manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV as claimed in claim 1, characterized in that: A slot is provided on the base, and an insert block is provided at the bottom of the sliding seat. The length of the slot along the axial direction of the connecting pipe is greater than the length of the insert block. The insert block is arranged in the slot, and a fixed block is also inserted between the insert block and the slot in the length direction.

5. The manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV as claimed in claim 4, characterized in that: The fixing block is in an inverted L-shape, the upper portion of the fixing block is located on the base via support bolts, and the bottom of the fixing block is wedge-shaped.

6. The manufacturing fixture for the titanium alloy front fuselage joint frame of a UAV as claimed in claim 1, characterized in that: The fixed seat and the sliding seat are both provided with a placement platform for placing the joint, and a pressure block for pressing the joint is provided above the placement platform. The pressure block is fixed to the base through a first pressing component; or fixed to the placement platform through a second pressing component.

7. A manufacturing process for a titanium alloy front fuselage joint frame for an unmanned aerial vehicle, characterized by: When welding, fix the sliding seat on the base, fix the connecting pipe on the pipe seat, fix the joint on the fixed seat and the sliding seat respectively, and adjust the relative position of the connecting pipe and the joint; When relieving stress after welding, remove the fixed constraints of the sliding seat and the base so that the sliding seat can slide freely along the length direction, and loosen the fixation of the tube seat and the connecting pipe to maintain a small movable gap between it and the connecting pipe; put the entire device into a vacuum furnace, and the parts will heat up with the furnace. During the heat treatment heating process, the parts will expand, driving the sliding seat to move, and at the same time the connecting pipe will extend on the tube seat; the opposite will happen when the temperature is lowered.

8. The manufacturing process of the titanium alloy front fuselage joint frame of the UAV according to claim 7, characterized in that: During welding, the first pressing assembly is used to fix the joint and the sliding seat on the base; during stress relief after welding, the second pressing assembly is used to fix the joint on the sliding seat.

9. The manufacturing process of the titanium alloy front fuselage joint frame of the UAV as claimed in claim 8 comprises the following stages: Pickling: Pickle the prefabricated connecting pipes and all joints separately to thoroughly remove surface oxides and contaminants; Dehydrogenation: After pickling, the connecting pipes and all joints are subjected to dehydrogenation treatment respectively, placed in a special oven, and heated and kept warm according to regulations to remove the hydrogen elements that may be introduced during the pickling process; Assembly: Fix the sliding seat on the base, fix the connecting pipe on the pipe seat, fix the joint on the fixed seat and sliding seat respectively, and adjust the relative position of the connecting pipe and joint; Positioning welding: After confirming that the positions of all components are adjusted correctly, perform symmetrical and uniform spot welding in the circumferential direction of the connecting pipe and each joint to initially fix the connecting pipe and each joint together; Argon arc welding: After completing the positioning welding, continuous argon arc welding is performed along the entire circumferential seam where the connecting pipe and each joint are connected, so that the connecting pipe and each joint are completely welded into an integral frame structure; Fitter: After welding is completed, perform fitter finishing; Post-weld stress relief: Remove the fixed constraints of the sliding seat and the base to allow the sliding seat to slide freely along the length direction, and loosen the fixation of the support platform and the connecting pipe to leave a small movable gap between it and the connecting pipe; put the entire device into a vacuum furnace, and the parts will heat up with the furnace. During the heat treatment process, the parts will expand, driving the sliding seat to move, and at the same time the connecting pipe will extend on the pipe seat; the opposite will happen when the temperature is lowered; Cleaning: After the heat treatment is completed, wait for the parts to cool to a safe operating temperature and remove them from the heat treatment tooling; perform a final cleaning on the removed frame parts to thoroughly remove any oil and dust that may have remained during the heat treatment process.

10. The manufacturing process of the titanium alloy front fuselage joint frame of the UAV as claimed in claim 9 comprises the following stages: When removing hydrogen, heat up to 120-150℃ in stages and keep warm for 60-120min; carry out hydrogen content test on the accompanying test piece (when the pickling thickness of each side is 0.025, the amount of hydrogen added shall not exceed 0.003%; When welding, use dust-free paper or white silk cloth dipped in alcohol or acetone to wipe the area to be welded until there is no dirt, and do a good job of gas protection on the back or inside the tube; When tack welding, use argon arc welding to evenly weld 4-8 points around the joint and the connecting pipe on the tooling; When stress relieving, the vacuum pressure of the vacuum chamber should be evacuated to no more than 6.7×10-2Pa before heating the parts; the parts are heated with the furnace, and the timing starts when the control instrument reaches the set temperature of 580℃, and the holding time is 60-90 minutes; after the holding period, the parts are cooled with the furnace to ≤400±10℃, and then cooled to ≤100℃ by 2bar argon gas, and then air-cooled after being taken out of the furnace.

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