Linear friction welding reinforcement process method for deep cavity curved surface of complex uniform-section titanium alloy profile

Abstract

The invention relates to the technical field of titanium alloy solid-phase pressure friction welding, in particular to a complex uniform-section titanium alloy profile deep cavity curved surface linear friction welding reinforcement process method which comprises the following steps: S1, equipment preparation: a titanium alloy Y profile and a rib plate are respectively clamped in an upsetting cylinder and a vibration cylinder of a hydraulic linear friction welding platform; the alignment precision is controlled to be smaller than or equal to 0.05 mm and the hydraulic clamping force is controlled to be smaller than or equal to 40 kN through a fine adjustment S2, parameter setting: based on finite element simulation, setting the amplitude of + / -5mm, the frequency of 50Hz, the friction pressure of 70kN, the upsetting pressure of 75kN, the upsetting time of 30s and the axial shortening amount of 5mm, and adopting a displacement control mode; according to the method, the reserved sectional area of the blank is reduced, the load and energy consumption of extrusion equipment are reduced, the manufacturing period is shortened, the material utilization rate is increased, the joint structure uniformity is improved through thermal-mechanical coupling regulation and dynamic recrystallization, the forming precision is improved, cutting waste liquid and dust emission is avoided, and the technological process is low-carbon and energy-saving.

Description

Technical Field

[0001] This invention relates to the field of solid-state pressure friction welding technology for titanium alloys, specifically a method for reinforcing complex uniform cross-section titanium alloy profiles with deep cavity curved surface linear friction welding. Background Technology

[0002] To achieve high performance, significant weight reduction, and long service life, the new generation of large aircraft extensively utilizes carbon fiber reinforced resin matrix composite (CFRP) integral structures (such as the Boeing 787 and Airbus A360XWB, where composite materials account for over 50% of the airframe structural weight). Due to the galvanic corrosion inherent in aluminum alloys and carbon fiber composites, titanium alloys, with their high specific strength, corrosion resistance, and compatibility with composite materials, have become the preferred material for locally reinforcing irregularly shaped curved components (such as…). Figure 1 (used to support composite skin panels).

[0003] The aforementioned locally reinforced irregular titanium alloy components have characteristics of deep cavities, complex cross-sections, thin walls, and high ribs. Traditional CNC milling processes present the following problems:

[0004] 1. High manufacturing cost: Rib processing requires a lot of milling, the blank reserved cross-sectional area is large (extrusion equipment load is high and energy consumption increases dramatically), the material removal rate exceeds 60% (utilization rate is less than 40%), the processing cycle is long (single rib milling ≥ 20 seconds), and the overall cost is 30%-50% higher than that of this invention.

[0005] 2. Poor forming quality: Extrusion of large cross-sectional area blanks can easily lead to incomplete filling and uneven metal flow, resulting in uneven profile density and low dimensional accuracy (surface roughness ≥ Ra3.2μm).

[0006] 3. Poor environmental performance: The discharge of cutting waste fluid and dust causes pollution.

[0007] To address this, we propose a linear friction welding reinforcement process for deep-cavity curved surfaces of complex uniform cross-section titanium alloy profiles. Summary of the Invention

[0008] The purpose of this invention is to provide a linear friction welding reinforcement process for deep cavity curved surfaces of complex uniform cross-section titanium alloy profiles. This process has the advantages of low manufacturing cost, good forming quality, and good environmental performance. It solves the problems of traditional CNC milling processes for locally reinforced irregular titanium alloy components with deep cavities, complex cross-sections, thin walls, and high ribs.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for linear friction welding reinforcement of deep cavity curved surfaces in complex uniform cross-section titanium alloy profiles, comprising the following steps:

[0010] S1. Equipment preparation: Clamp the titanium alloy Y-profile and the stiffening plate respectively in the upsetting cylinder and vibration cylinder of the hydraulic linear friction welding platform, and control the alignment accuracy ≤0.05mm and the hydraulic clamping force ≤40kN through the fine adjustment mechanism.

[0011] S2. Parameter settings: Based on finite element simulation, the amplitude is set to ±5mm, the frequency to 50Hz, the friction pressure to 70kN, the upsetting pressure to 75kN, the upsetting time to 30s, and the axial shortening to 5mm. The displacement control mode is adopted.

[0012] S3. Processing and forming: The process sequentially goes through the initial stage, transition stage, equilibrium stage, and upsetting stage to achieve interface deoxidation, viscoplastic flow, dynamic recrystallization, and martensitic phase transformation.

[0013] S4. Unloading and finishing: After welding is completed, depressurize and release the hydraulic clamps, remove the workpiece, save the welding process data, and shut down the equipment.

[0014] Preferably, in step S1, after the hydraulic linear friction welding platform is started, it is necessary to wait for the oil pump to store energy for 10 minutes to ensure that the accumulator pressure reaches 25MPa.

[0015] Preferably, in step S2, the finite element simulation is constructed using Simufact Forming, and the weld area uses 0.6mm thermo-mechanically coupled hexahedral elements, combined with ALE mesh adaptive technology to optimize mesh quality.

[0016] Preferably, in the initial stage, the stiffener plate undergoes horizontal vibration with an amplitude of ±5mm and a frequency of 50Hz. The Y-shaped profile gradually approaches the stiffener plate until it makes contact, and the oxide layer is removed by friction from the microscopic protrusions at the interface, without any visible flash.

[0017] Preferably, during the transition stage, the forging cylinder advances to the position before the weld, the friction pressure rises to 70kN, the interface temperature rises to 1200℃, the plastic material is extruded with initial flash, the β grains are elongated and dynamic recrystallization is initiated at the grain boundaries.

[0018] Preferably, during the equilibrium stage, the interface temperature is stabilized at 972°C, the flash is continuously and uniformly extruded, dynamic recrystallization is completed, equiaxed β grains are formed, and the residual interface oxide is ≤5%.

[0019] Preferably, during the upsetting stage, the rib vibration stops within 100ms, a 75kN upsetting pressure is applied simultaneously and held for 30s, a large amount of thermoplastic material is extruded, and the β phase rapidly cools and transforms into... Martensitic structure, weld compaction and shaping.

[0020] Preferably, in step S4, before unloading, the pressure relief knob of the proportional relief valve must be closed to release the pressure, and the hydraulic clamp should be released to remove the part after the cylinder pressure drops to ≤5kN.

[0021] Preferably, in step S2, the finite element simulation needs to calculate parameters such as axial shortening and flash volume, using the following formula:

[0022] , ,

[0023] Total extrusion volume Verify the rationality of the parameters.

[0024] In the formula, The thickness of the stiffening rib (unit: mm). The angle between the inclined plane of the Y-shaped section and the horizontal plane (unit: , ), Axial shortening (unit: mm) ), The length of the base of the hypotenuse on both sides of the Y-shaped cross-section (unit: mm). ), The included angle of the polyhedrons corresponding to the center fillet (unit: , ,Depend on (Derivation) Center fillet radius (unit: mm) ), The extruded volume of material on both inclined sides (unit: mm³); Extruded volume of material for the central rounded corner area (unit: mm³); Total extrusion amount (unit: mm³ / mm²).

[0025] A method for reinforcing complex uniform cross-section titanium alloy profiles by deep cavity curved surface linear friction welding is provided. The process is applied to TC4 titanium alloy Y-shaped cross-section profiles, which are prepared by induction heating at 1050℃ for 1.5 hours, extrusion, annealing at 750℃ for 2 hours, and furnace cooling.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention reduces the reserved cross-sectional area of ​​the billet, reduces the load and energy consumption of the extrusion equipment, shortens the manufacturing cycle, and improves the material utilization rate.

[0028] 2. This invention improves the uniformity of joint structure and enhances molding accuracy through thermo-mechanical coupling control and dynamic recrystallization.

[0029] 3. This invention produces no cutting waste fluid or dust emissions, and the process is low-carbon and energy-saving. Attached Figure Description

[0030] Figure 1This is a schematic diagram illustrating the application of the locally reinforced irregularly shaped titanium alloy curved surface component of the present invention in the body structure;

[0031] Figure 2 The extrusion-annealing process curve and Widmanstätten microstructure of the TC4 titanium alloy of this invention are shown below.

[0032] Figure 3 This invention relates to a high-temperature compression experimental apparatus and a temperature-time curve.

[0033] Figure 4 The figures show the actual stress-strain curves of TC4 at different temperatures according to this invention.

[0034] Figure 5 This is a finite element simulation model of the Y-shaped cross-section linear friction welding of the present invention;

[0035] Figure 6 This is a curve showing the upsetting force versus axial shortening during the welding process of this invention.

[0036] Figure 7 This is a three-dimensional structural diagram of the self-developed hydraulic linear friction welding experimental platform of this invention;

[0037] Figure 8 This is a diagram showing the cross-sectional parameters of the Y-shaped profile of the present invention and the positional relationship between the Y-shaped profile and the stiffening plate during welding. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0039] (I) Design Basis

[0040] 1. Preparation and Properties of TC4 Titanium Alloy

[0041] Preparation process: Titanium ingots are induction heated to 1050℃ (held for 1.5h) → extruded → annealed at 750℃ (held for 2h) → furnace cooled to form Widmanstätten structure (α phase lamellar layers + β phase bundles). Figure 2 ).

[0042] High-temperature deformation window: determined by high-temperature compression test ( Figure 3 The reasonable range for linear friction welding is determined as follows: deformation temperature 500-1000℃, strain rate 0.001-1s. - ¹(The flow stress is highest at 700℃, and the yield strength drops to 46MPa at 1000℃.) Figure 4 ).

[0043] 2. Deep cavity surface simulation modeling

[0044] Model construction: For Y-shaped cross-sections ( Figure 8With a cross-sectional area of ​​5.32 in², an included angle of 36°, and a fillet radius of R.250±0.062 mm, and a stiffener thickness of 10 mm, a thermo-mechanical coupling model is constructed. Figure 5 ).

[0045] Key parameters:

[0046] Unit: The weld zone uses 0.6mm hexahedral units (characterizing high-temperature large plastic deformation), and the clamps / profiles are discrete rigid bodies;

[0047] Mesh: ALE adaptive + gradient meshing to avoid mesh distortion on deep cavity surfaces;

[0048] Boundary: Initial temperature 25℃, 70kN friction pressure applied in the Z direction, and clamp amplitude ±5mm and frequency 50Hz reciprocating motion set in the X direction;

[0049] Optimization results: With an axial shortening of 5mm, an upsetting pressure of 75kN, and a holding pressure of 30s, the optimal temperature rise rate, equilibrium temperature (972℃), and extrusion rate are achieved. Figure 6 Simulation curve).

[0050] 3. Mechanism of the welding stage

[0051]

[0052] (II) Process Steps

[0053] 1. Equipment preparation (self-developed hydraulic linear friction welding platform) Figure 7 )

[0054] Equipment structure analysis:

[0055] like Figure 7 As shown: 1 is the shock-absorbing pad, 2 is the horizontal bed, 3 is the upsetting servo system, 4 is the upsetting column, 5 is the top crossbeam, 6 is the upsetting worktable, 7 is the hydrostatic guide rail, 8 is the vertical bed, 9 is the vibration servo system, 10 is the hydraulic clamp, and 11 is the profile to be pressed (1m-3m).

[0056] The platform adopts a symmetrical layout of "2 horizontal bed frames + 8 vertical bed frames":

[0057] Upsetting system: Upsetting servo system 2 is fixed to horizontal bed 2 through upsetting column 4, and drives upsetting worktable 6 to perform axial upsetting movement along hydrostatic guide rail 7 (positioning accuracy ±0.01mm).

[0058] Vibration system: Vibration servo system 9 is integrated into vertical bed 8, driving hydraulic clamp 10 to carry stiffener plate to perform linear reciprocating vibration (amplitude ±5mm, frequency 50Hz, motion accuracy ±0.05mm).

[0059] Auxiliary modules: Top beam 5 enhances equipment rigidity, and shock-absorbing pad 1 attenuates vibration interference (natural frequency ≤10Hz) to ensure stable welding process.

[0060] Clamping and verification:

[0061] Y-shaped profile ( Figure 8 A custom clamping block is held in place on the upsetting worktable 6, and the stiffener is fixed to the hydraulic clamp on the vibrating side. A clamping force of 40kN is applied (closed-loop control of pressure sensor, error ≤1kN). The alignment is finely adjusted by a coordinate measuring machine: axial deviation ≤0.05mm, radial deviation ≤0.10mm, to ensure interface contact uniformity ≥95%.

[0062] Start-up and energy storage:

[0063] Start oil pump motors 1-3 in sequence and wait 10 minutes for energy storage (accumulator pressure reaches 25MPa, pump source operation indicator light is all green); start the hydrostatic guide rail oil pump (oil film thickness ≥0.02mm, operation indicator light is on).

[0064] 2. Process parameter settings (host computer interface)

[0065] Basic parameters:

[0066] The pre-welding position is set to "slide table compaction displacement x-10mm", and the pre-weld position is "x+2mm" (x is the measured compaction displacement; in this example, x=85.2mm, so the pre-welding position is 75.2mm and the pre-weld position is 87.2mm). Friction stop control is displacement control.

[0067] Welding parameters:

[0068] Amplitude ±5mm (closed-loop control and verification via the built-in electronic scale of the machine tool vibration cylinder, error ≤0.05mm), frequency 50Hz (encoder feedback), friction pressure 70kN, upsetting pressure 75kN, upsetting time 30s, axial shortening 5mm (displacement sensor closed-loop control).

[0069] Simulation verification:

[0070] Verify the rationality of the parameters by calculating the extrusion amount using the formula:

[0071] Let the angle between the inclined planes be... Center fillet radius Length of the sloping base rib thickness Axial shortening :

[0072] ,

[0073] ,

[0074] ,

[0075] ,

[0076] The simulation results deviate from the formula calculation by ≤5%, confirming the validity of the parameters.

[0077] Hollow vibration verification:

[0078] The vibrating cylinder was left to vibrate for 1 second to confirm that the amplitude and frequency were correct (RMCTOOL recorded the curve).

[0079] 3. Processing and forming stage

[0080] Initial phase (0-1.5s):

[0081] The forging cylinder moves to 75.2 mm at 5 mm / s, and the vibration cylinder starts to vibrate; the interface shows microscopic convex peak friction (noise ≥85dB, vibration acceleration ≥10g), the oxide layer is broken (SEM observation: residual oxide at the interface ≤10%), and there are no visible flash.

[0082] Transition phase (1.5-2.5s): The upsetting cylinder moves to 87.2mm at a speed of 3mm / s, and the friction pressure increases linearly to 70kN (pressure increase rate 10kN / s).

[0083] The interface temperature rises to 1200℃ (TC4 single-phase β region) at a rate of 100℃ / s, strain rate (Meets the viscoplastic flow conditions, and the strain rate is the result of theoretical derivation → simulation quantification → experimental verification), extruding the initial flash (width 2mm, color light yellow / blue).

[0084] EBSD analysis: β grains are elongated, and the dynamic recrystallization nucleation rate at grain boundaries is ≥30%.

[0085] Equilibrium phase (2.5-6.0s):

[0086] Temperature stabilized at 972℃ (measured non-contactly by a laser temperature sensor, error ≤5℃), flash was continuously extruded at a rate of 0.5mm / s; EBSD analysis: average size of equiaxed β grains ≤10μm, interface oxide residue ≤5% (self-cleaning completed).

[0087] Upsetting stage (6.0-6.3s):

[0088] The vibration cylinder stops vibrating within 100ms (servo system response time ≤ 50ms), the upsetting pressure is raised to 75kN and held for 30s; thermoplastic TC4 is extruded in large quantities (total flash width 8-10mm), the β phase is rapidly cooled (cooling rate ≥ 100℃ / s), and transforms into... Martensite (TEM observation: needle-like martensite bundles ≤5μm).

[0089] 4. Uninstallation and Detection

[0090] Depressurization and part retrieval:

[0091] Close the proportional relief valve pressure boosting knob. After the cylinder pressure drops to ≤5kN, release the hydraulic clamp to remove the part.

[0092] Detection:

[0093] Appearance: Uniform flash, no cracks (visual inspection + fluorescence penetration test);

[0094] Flaw detection: Ultrasonic testing for defects ≤ φ0.5mm (focused probe, frequency 5MHz).

[0095] The following examples, along with attached diagrams, illustrate the process (TC4 titanium alloy Y-section profile, stiffener thickness 10mm, section parameters as follows). Figure 8 The present invention will be described in detail below.

[0096] I. Material Preparation and Pretreatment

[0097] 1. Preparation of TC4 titanium alloy:

[0098] Induction heating: The titanium ingot is heated to 1050℃ at a rate of 15℃ / s and held for 1.5h (temperature uniformity within the furnace ±5℃).

[0099] Extrusion molding: Die temperature 350℃, extrusion ratio 8:1, to ensure profile dimensional accuracy (tolerance ±0.05mm).

[0100] Annealing treatment: Heat to 750℃ at 10℃ / min, hold for 2 hours, and then furnace cool to room temperature at 5℃ / min to obtain Widmanstätten structure (α phase lamellar layer thickness ≤ 5μm).

[0101] 2. Y-shaped profile and stiffening plate processing:

[0102] Y-profile: Milled 4 clamping surfaces, straightness error ≤0.05mm (measured with dial indicator);

[0103] Rib plate: 10mm thick, surface roughness Ra≤1.6μm (grinding with a grinding wheel), pickling to remove oxide scale (formula: HF:HNO3:H2O=1:3:10, soak for 30s, rinse with water).

[0104] II. Finite Element Simulation Modeling

[0105] 1. Model Construction: Import Y-shaped section drawing ( Figure 8 Define the stiffener thickness as 10mm, the multi-faceted included angle as 36°, and the transition fillet radius as R.250mm;

[0106] The weld zone (contact interface ±2mm) is divided into 0.6mm hexahedral elements (thermal-mechanical coupling), and the clamps and profiles are set as discrete rigid bodies (reducing the amount of calculation by more than 30%).

[0107] 2. Parameter settings:

[0108] Boundary conditions: initial temperature 25℃, Y profile is subjected to 70kN friction pressure in the Z direction, stiffener is set to reciprocate with amplitude ±5mm and frequency 50Hz in the X direction (constraining Y and Z direction displacements).

[0109] Material model: Embedded TC4 high-temperature stress-strain curve ( Figure 4 Temperature-friction coefficient fitting formula:

[0110] 3. Simulation Analysis:

[0111] When the axial shortening is 5mm, the total extrusion amount reaches 12.5mm³ / mm² (uniform flash, no folds).

[0112] Temperature field: The interface center reaches 1200℃ (β phase region) during the transition stage and is stable at 972℃ (near the β phase transition point of 995℃) during the equilibrium stage, which meets the dynamic recrystallization thermodynamic conditions (recrystallization activation energy ≤200kJ / mol).

[0113] III. Process Implementation (Self-developed hydraulic linear friction welding platform) Figure 7 )

[0114] 1. Equipment startup and commissioning:

[0115] Clamping verification: After the Y-profile and the stiffening plate are aligned, use a feeler gauge to check that the gap is ≤0.05mm;

[0116] Energy storage and no-load vibration: After the oil pump is started, wait 10 minutes (the accumulator pressure reaches 25MPa), then let the vibration cylinder vibrate for 1 second. Verify the amplitude of 5mm (error ≤0.05mm) using the electronic scale built into the machine tool vibration cylinder.

[0117] 2. Input of process parameters (host computer interface):

[0118] Enter the pre-weld position as 75.2mm and the pre-weld position as 87.2mm, and check "Displacement Control";

[0119] Enter the welding parameters: amplitude 5mm, frequency 50Hz, friction pressure 70kN, upsetting pressure 75kN, upsetting time 30s, axial shortening 5mm (the system will automatically verify the rationality).

[0120] 3. Welding process control:

[0121] Initial phase (0-1.5s):

[0122] The upsetting cylinder moves to 75.2 mm at a speed of 5 mm / s, and the vibration cylinder starts to vibrate; the interface friction noise is ≥85 dB, and the vibration acceleration is ≥10 g (monitored by the acceleration sensor).

[0123] Transition phase (1.5-2.5s):

[0124] The forging cylinder moves to 87.2 mm at a speed of 3 mm / s, and the friction pressure rises to 70 kN; the laser temperature sensor displays that the center of the interface reaches 1200℃, and the initial flash (2 mm wide, light yellow in color) is extruded.

[0125] Equilibrium phase (2.5-6.0s):

[0126] Temperature stabilized at 972℃ (measured non-contactly via laser temperature sensor, error ≤5℃), flash was continuously extruded at a rate of 0.5mm / s, and the force-displacement curve recorded by RMCTOOL was stable.

[0127] Upsetting stage (6.0-6.3s):

[0128] The vibration cylinder stops vibrating within 100ms (servo system response time ≤ 50ms), the upsetting pressure rises to 75kN and is held for 30s; the total width of the flash reaches 8mm, and the weld area cools rapidly (cooling rate ≥ 100℃ / s).

[0129] 4. Uninstallation and Detection:

[0130] Depressurization: Rotate the pressure boosting knob to the "stop" position until the cylinder pressure drops to ≤5kN;

[0131] Detection:

[0132] Appearance: Uniform flash, no cracks (visual inspection + fluorescence penetration test);

[0133] Flaw detection: Ultrasonic testing for defects ≤ φ0.5mm (focused probe, frequency 5MHz).

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A deep-cavity curved linear friction welding stiffening process method for complex constant cross-section titanium alloy profiles, characterized in that, The method comprises the following steps: S1. Equipment preparation: titanium alloy Y-shaped section and rib plate are respectively clamped on the top forging cylinder and vibration cylinder of the hydraulic linear friction welding platform, the positioning accuracy is controlled to be less than or equal to 0.05 mm through the fine adjustment mechanism, and the hydraulic clamping force is less than or equal to 40 kN; S2. Parameter setting: based on finite element simulation, the amplitude is set to ±5 mm, the frequency is set to 50 Hz, the friction pressure is set to 70 kN, the top forging pressure is set to 75 kN, the top forging time is set to 30 s, the axial shortening amount is set to 5 mm, and the displacement control mode is adopted; S3. Machining forming: sequentially experiencing an initial stage, a transition stage, a balance stage and a top forging stage, interface deoxidation, viscous plastic flow, dynamic recrystallization and martensite phase change are realized; S4. Unloading and finishing: after the welding is completed, the hydraulic clamp is released, the workpiece is taken out, the welding process data is saved, and the equipment is turned off.

2. The process for linear friction welding of stiffener to complex constant cross-section titanium alloy profile deep cavity curved surface according to claim 1, characterized in that: In step S1, after the hydraulic linear friction welding platform is started, the oil pump needs to be energized for 10 minutes to ensure that the accumulator pressure reaches 25 MPa.

3. The process of claim 1, wherein the complex constant cross-section titanium alloy profile deep-cavity curved linear friction welding stiffening process is characterized by: In step S2, the finite element simulation is constructed by Simufact Forming, the 0.6 mm thermal-mechanical coupling hexahedral element is used in the weld area, and the ALE mesh self-adaptive technology is used to optimize the mesh quality.

4. The process of claim 1, wherein the complex constant cross-section titanium alloy profile deep-cavity curved linear friction welding stiffening process is characterized by: In the initial stage, the rib plate is horizontally excited with an amplitude of ±5 mm and a frequency of 50 Hz, the Y-shaped section gradually approaches the rib plate until contact, the interface micro convex peak removes the oxide layer, and no visible flash is generated.

5. The process of claim 1, wherein the process is a linear friction welding process for reinforcing a deep-cavity curved surface of a complex constant cross-section titanium alloy profile. In the transition stage, the top forging cylinder advances to the position in front of the weld, the friction pressure rises to 70 kN, the interface temperature rises to 1200℃, the plastic material extrudes the initial flash, the beta grain is elongated and the dynamic recrystallization is started at the grain boundary.

6. The process of claim 1, wherein the process is a linear friction welding process for reinforcing a deep-cavity curved surface of a complex constant cross-section titanium alloy profile. In the balance stage, the interface temperature is stabilized at 972℃, the flash is continuously and uniformly extruded, the dynamic recrystallization is completed, the equiaxed beta grains are formed, and the interface oxide residue is less than or equal to 5%.

7. The process of claim 1, wherein the process is a linear friction welding process for reinforcing a deep-cavity curved surface of a complex constant cross-section titanium alloy profile. In the top forging stage, the rib plate excitation stops within 100 ms, 75 kN top forging pressure is applied synchronously and pressure is maintained for 30 s, a large amount of thermoplastic material is extruded, and the β phase is rapidly cooled to transform into martensite, and the weld is compacted and shaped.

8. The process of claim 1, wherein the process is a linear friction welding process for reinforcing a deep-cavity curved surface of a complex constant cross-section titanium alloy profile. In step S4, before unloading, the proportional overflow valve pressure increasing knob is closed to release the force, and after the oil cylinder pressure is reduced to less than or equal to 5 kN, the hydraulic clamp is released to take out the workpiece.

9. The process of claim 1, wherein the process is a linear friction welding process for reinforcing a complex constant cross-section titanium alloy profile with a deep cavity and curved surface. In step S2, the finite element simulation needs to calculate the axial shortening amount and the flash volume, and the formula is: ， ， ； Total extrusion , verifying parameter rationality, In the formula, is the thickness of the web, is the included angle between the inclined surface of the Y-shaped cross section and the horizontal plane, is the axial shortening amount, is the length of the base of the two inclined sides of the Y-shaped cross section, is the included angle of the multi-faces corresponding to the center fillet, is the radius of the center fillet, is the material extrusion volume of the two inclined sides; is the material extrusion volume of the center fillet area; is the total extrusion amount.

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