A method for controlling deformation prevention during machining of titanium alloy thick-walled profiles

Abstract

The present invention belongs to the technical field of machining titanium alloy profiles, and discloses a method for controlling deformation prevention during machining of titanium alloy thick-walled profiles. A combination of rough machining and fine machining is adopted during the machining of titanium alloy thick-walled profiles. Rough machining adopts a symmetrical machining method to evenly remove the excess on both sides of the titanium alloy profile, ensuring that the parts release stress evenly to both sides along the symmetry line. Fine machining includes semi-finishing and fine machining, and a symmetrical machining method is adopted to evenly remove the excess on both sides of the titanium alloy profile, ensuring that the parts release stress evenly to both sides along the symmetry line. Vacuum annealing heat treatment is added between rough machining and fine machining. When the profile is severely deformed after rough machining, vacuum annealing heat treatment is carried out simultaneously with mold thermal correction. The method of the present invention effectively solves the difficult problems of severe deformation and inability to guarantee wall thickness dimensional tolerance during machining of titanium alloy thick-walled profiles due to their long longitudinal dimensions, thin wall thickness, and residual stress inside.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy profile machining, and particularly relates to a titanium alloy thick-wall profile machining anti-deformation control method. Background Art

[0002] Foreign civil aircraft are continuously increasing the use of titanium alloys in consideration of the comprehensive balance between weight reduction, cost, performance and maintenance. As the application of titanium and titanium alloys in aircraft becomes increasingly widespread, the scope and amount of use of titanium profiles are also beginning to expand. Titanium alloy profiles produced in Russia and European and American countries have been widely used in aircraft. The seat slides of European Airbus series aircraft use large-section profiles of Ti-6Al-4V (domestic brand TC4) titanium alloy (cross-sectional area 15000mm 2 ), the United States also selected Ti-6Al-4V titanium alloy profiles for B787 frames and seat rails, wing and outer wing connection edge strips, etc. The titanium alloy profiles produced by RTI, the largest titanium alloy manufacturer in the United States, were successfully used in the "T"-shaped horizontal stabilizer reinforcement ribs and "L"-shaped wing beams on the B-777, and the " "-shaped flap rails, etc. A certain type of military aircraft in my country uses a large number of TA15 and TC2 titanium alloy thin-walled precision profiles, which are mainly used in various parts of the aircraft such as the engine compartment, landing gear compartment, tail boom, tail cover, air conditioning system, fire protection system, etc., and are concentrated in the rear fuselage, including the upper and lower longitudinal profile beams of the tail boom, the upper and lower wall plate reinforcement ribs of the tail boom, the engine compartment 21 long stringers, T-shaped connecting joints and other load-bearing components, as well as 45A frames and longitudinal partitions of the tail cover. Ti-6Al-4V titanium alloy profiles are also used on my country's domestically produced large passenger aircraft C919.

[0003] Ti-6Al-4V titanium alloy belongs to +β-type titanium alloy is mainly characterized by medium strength, excellent comprehensive performance and good processing characteristics. The global output of Ti-6Al-4V titanium alloy semi-finished products accounts for more than half of the total output of various titanium alloy semi-finished products. In the aerospace industry, more than 80% of titanium alloys are Ti-6Al-4V. Ti-6Al-4V titanium alloy treated with β can obtain a very low fatigue crack growth rate (da / dN), while obtaining a good matching relationship between toughness, plasticity and strength, which is more in line with damage tolerance design requirements. Over the years, my country has conducted in-depth research on the composition, process, microstructure and properties of Ti-6Al-4V alloy, and has produced a variety of specifications of bars, sheets, thick plates, pipes, wires and profiles. The forming technology of this alloy is becoming more and more mature.

[0004] To reduce structural weight, large aircraft commonly utilize integrally machined titanium alloy components for complex, thin-walled structures, such as panels, frames, and joints. However, due to their thin walls and low rigidity, excessive deformation after machining can affect the aircraft's proper assembly. Stress-induced assembly can also affect the fatigue life and load-bearing capacity of the assembled structure, significantly negatively impacting the aircraft's overall lifespan, performance, and quality. Titanium alloys are chemically active and have poor thermal conductivity, resulting in significant springback and distortion during machining. The main difficulties in machining titanium alloy profiles are severe tool wear, high cutting temperatures, high cutting forces per unit area, and severe chilling. Due to their relatively low rigidity, springback is easily generated during machining, leading to friction between the tool flank and the machined surface, increasing tool wear. Furthermore, these parts typically have complex shapes and demand high machining and positioning accuracy, making machining precision difficult to guarantee. Localized surface blackening may occur after machining, making machining efficiency difficult to guarantee. At the same time, when processing thin-walled structural parts, the amount of material removed is relatively large, and there is residual stress inside. Due to the reduction in part stiffness and the release of stress after material removal, large processing deformation is caused. Titanium alloy profile parts are characterized by long longitudinal dimensions, thin side walls, and thin webs. They are difficult to clamp during processing, and the tool overhang is large, which makes cutting chatter prone to occur, resulting in excessive surface roughness of the parts and increasing the subsequent grinding workload. This poses serious hidden dangers to the application of titanium alloy profile parts. If a single-sided processing process is used, although positioning is simple, the local stress concentration is large and deformation is easy. If processing is started from both sides to reduce stress concentration, it is necessary to change the surface multiple times to find the reference, positioning is difficult, and part accuracy is difficult to guarantee.

[0005] Therefore, anti-deformation control is crucial during the machining of titanium alloy profiles, and it is urgent to improve the machining process of titanium alloy profiles according to the structural characteristics of titanium alloy parts. Summary of the Invention

[0006] The purpose of the present invention is to propose a method for controlling deformation prevention during machining of thick-walled titanium alloy profiles, so as to solve the problems that the current domestic titanium alloy profiles (especially those with a wall thickness of 6mm to 20mm) have large internal residual stress, uneven thickness and large warping deformation, and that complex parts with long longitudinal dimensions, thin side walls, thin webs and multiple steps suffer from severe deformation and poor dimensional accuracy after machining.

[0007] To solve this technical problem, the technical solution of the present invention is:

[0008] A method for controlling deformation prevention during machining of titanium alloy thick-walled profiles, the method comprising the following steps:

[0009] Step 1: Prepare a titanium alloy thick-wall profile of a fixed length ≥ 2000mm, and ensure that the profile straightness meets the following requirements: the torsion angle around the longitudinal axis in any 300mm length should not be greater than 1°, the transverse curvature in any 25mm width should not be greater than 0.25mm, and the longitudinal curvature in any 300mm length should not be greater than 0.65mm;

[0010] Step 2: Rough machining according to the shape of the part:

[0011] Rough milling of the titanium alloy profile blank surface, the surface thickness allowance should be greater than 5mm; rough machining is performed according to the part shape, excess material is removed, and process bosses are set as needed; during the rough machining process, the milling speed is controlled between 20m / min and 45m / min, the feed rate is controlled between 0.06mm / z and 0.12mm / z, the milling width is controlled between 1mm and 4mm, and the milling depth is controlled between 0.5mm and 1mm;

[0012] Step 3: Vacuum stress relief annealing:

[0013] The rough-machined titanium alloy profile is subjected to vacuum stress relief annealing. The vacuum heat treatment furnace is preheated at 450°C for 30 minutes. The stress relief annealing temperature is set between 650°C and 760°C. After reaching the temperature, the profile obtained in step 2 is loaded and kept at this temperature for 30 minutes to 60 minutes. The profile is cooled with the furnace to below 280°C, then taken out of the furnace and air-cooled to room temperature.

[0014] Step 4: Finishing according to the shape of the part:

[0015] Each surface of the titanium alloy profile is finish milled to the theoretical size. The total material removal distribution value of each surface is determined according to the deformation of the part. Semi-finishing is performed according to the basic structure of the part, and the process boss is removed. The allowance after semi-finishing is controlled at 0.5mm~1mm. After semi-finishing is completed, finish machining is performed to the theoretical shape. During semi-finishing and finishing, the milling speed is controlled between 20m / min~40m / min, the feed rate is controlled between 0.04mm / z~0.08mm / z, the milling width is controlled between 1mm~4mm, and the milling depth is controlled between 0.1mm~0.5mm.

[0016] In step 2, rough machining uses a symmetrical machining method to evenly remove the excess on both sides of the titanium alloy profile to ensure that the part releases stress evenly to both sides along the symmetry line, and the single-side allowance is controlled between 1.5mm and 2.5mm.

[0017] If the titanium alloy profile is severely deformed after rough machining (severe deformation means that it does not meet the straightness requirements of step 1), step 3, vacuum stress relief annealing, is performed simultaneously with vacuum straightening. The rough-machined titanium alloy profile is fixed to the straightening die, ensuring that the die's reference surface is parallel to the bottom surface of the titanium alloy profile. After vacuum straightening, the profile is cooled in the furnace to below 280°C and then removed from the furnace after air cooling to below 50°C.

[0018] Step 4: During the semi-finishing and finishing processes, a symmetrical processing method is used to evenly remove the excess on both sides of the titanium alloy profile to ensure that the part releases stress evenly on both sides along the symmetry line.

[0019] The method for controlling deformation during machining of titanium alloy profiles is applicable to thick-walled titanium alloy profiles with L-, T-, or U-shaped cross-sections and wall thicknesses of 6 mm to 20 mm. The method is also applicable to medium- and low-strength titanium alloys, particularly TC1, TC2, TC4, TA15, and TA21.

[0020] The profiles processed by the present invention are thick-walled titanium alloy profiles. The target parts are L-, T-, or U-shaped channel components used in aircraft. These are characterized by long longitudinal dimensions, thin sidewalls, thin webs, and complex, multi-step structures. Although the present method imposes strict requirements on the straightness of thick-walled profiles before processing in step 1, the initial profiles inevitably bend and twist during extrusion or roll forming due to their long longitudinal dimensions. This results in significant residual stress within the profile during subsequent self-heating or roll straightening. Therefore, whether in the rough machining or fine machining process, it will lead to serious problems such as internal residual stress release, local warping deformation, springback, and poor dimensional accuracy. Therefore, it is necessary to control the deformation of the entire machining process of thick-walled profiles according to the process parameters of steps 2, 3, and 4 of the present invention. When the titanium alloy profile is severely deformed after rough machining, the vacuum stress relief annealing in step 3 is carried out simultaneously with the vacuum shaping. The rough-machined titanium alloy profile is fixed on a special shaping mold to ensure that the reference surface of the special shaping mold is parallel to the bottom surface of the titanium alloy profile. After vacuum shaping, the profile is cooled to below 280°C in the furnace and then removed from the furnace. After air cooling to below 50°C, the special shaping mold is disassembled.

[0021] The beneficial effects of the present invention are:

[0022] The present invention is mainly aimed at the U-shaped slot parts of the flap section of titanium alloy profiles widely used on aircraft in my country, and adopts a combination of rough machining and fine machining. Rough machining adopts a symmetrical machining method to evenly remove the excess on both sides of the titanium alloy profile, ensuring that the stress of the part is evenly released to both sides along the symmetry line. Rough machining adopts milling method, with the milling speed controlled between 20m / min and 45m / min, the feed rate controlled between 0.06mm / z and 0.12mm / z, the milling width controlled between 1mm and 4mm, and the milling depth controlled between 0.5mm and 1mm, ensuring that the thickness allowance of the profile blank surface after rough machining is greater than 5mm. Fine machining includes semi-finishing and fine machining, and adopts a symmetrical machining method to evenly remove the excess on both sides of the titanium alloy profile, ensuring that the stress of the part is evenly released to both sides along the symmetry line. Semi-finishing is carried out according to the basic structure and reinforcement structure of the part. The excess after semi-finishing is controlled to 0.5mm to 1mm, and finally fine machining is carried out to the theoretical shape. During semi-finishing and finishing, the milling speed is controlled between 20m / min and 40m / min, the feed rate is controlled between 0.04mm / z and 0.08mm / z, the milling width is controlled between 1mm and 4mm, and the milling depth is controlled between 0.1mm and 0.5mm. Vacuum annealing heat treatment is added between roughing and finishing. If the profile is severely deformed after roughing, vacuum annealing heat treatment is performed simultaneously with mold thermal alignment. The vacuum thermal alignment temperature is set between 650℃ and 760℃. Once the temperature reaches temperature, the titanium alloy profile is installed in a special alignment mold and held at this temperature for 30 to 60 minutes.

[0023] The invention has been used to complete the machining of multiple batches of domestic titanium alloy profiles. The processed profile parts have good surface finish and high dimensional accuracy. After fine machining, the internal residual stress of the profile is low, there is no machining deformation, the batch stability is high, and the repeatability is good. In addition, the method of the present invention has few process steps, simple process parameter setting, convenient operation, controllable process flow, and high machining qualification rate. By combining rough machining and fine machining, and adding vacuum annealing heat treatment after rough machining, on the one hand, it avoids the serious local deformation of the profile caused by the large internal residual stress brought about by one-time machining, and on the other hand, it can avoid the poor machining dimensional accuracy caused by uneven thickness and warping deformation of the profile blank, and effectively solves the problem of serious deformation and inability to guarantee wall thickness dimensional tolerance during machining of titanium alloy thick-walled profiles due to long longitudinal dimensions, thin wall thickness, and residual stress inside. When the rough machining deformation is serious, vacuum stress relief annealing is carried out simultaneously with vacuum shaping, which further ensures that the profile is not deformed after machining, and the machining qualification rate and machining efficiency are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic cross-sectional view of a TC4 titanium alloy U-shaped profile according to Example 1;

[0025] Figure 2 This is a schematic diagram of a typical load-bearing component of a TC4 titanium alloy U-shaped groove in Example 1;

[0026] Figure 3 Schematic diagram of the U-profile vacuum heat treatment shaping die in Example 1;

[0027] Figure 4 This is a schematic cross-sectional view of the TC4 titanium alloy T-section material of Example 2;

[0028] Figure 5 This is a schematic diagram of a typical T-shaped part of TC4 titanium alloy in Example 2;

[0029] Figure 6 Schematic diagram of the T-profile vacuum heat treatment shaping die in Example 2;

[0030] Figure 7 This is a schematic cross-sectional view of the TC2 titanium alloy L-profile of Example 3;

[0031] Figure 8 This is a schematic diagram of a typical L-shaped TC2 titanium alloy part in Example 3. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The features of various aspects of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to facilitate a comprehensive understanding of the present invention. In the description below, well-known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0033] The specific steps and processes of the present invention are described below in conjunction with titanium alloy profiles of different cross-sectional specifications.

[0034] Example 1:

[0035] The target typical part material grade is TC4, and the cross-section shape is "U". The wall thickness of the typical TC4 titanium alloy U-shaped part is 5mm±0.5mm on both sides and 11.5mm±0.5mm on the bottom edge. The specific machining steps are as follows:

[0036] Step 1: Prepare a thick-walled TC4 titanium alloy U-shaped profile with a U-shaped cross section (the wall thickness of the vertical edges of the TC4 titanium alloy U-shaped profile blank is 10 mm ± 0.5 mm, the bottom edge is 16.5 mm ± 0.5 mm, the angle between the inner side of the vertical edge and the bottom edge is 93°, and the profile length is 2100 mm). The torsion angle around the longitudinal axis over any 300 mm length is less than 1°, the transverse curvature over any 25 mm width is less than 0.25 mm, and the longitudinal curvature over any 300 mm length is less than 0.65 mm. Proceed to Step 2.

[0037] Step 2: For the fixed-size profile transferred in step 1, perform rough machining process programming according to the part shape. Rough mill the surface of the TC4 titanium alloy profile blank, perform rough machining according to the part shape, set process bosses, and use a symmetrical machining method to evenly remove the excess on both sides of the TC4 titanium alloy profile to ensure that the part releases stress evenly on both sides along the symmetry line, and the single-side allowance is controlled at 1.5mm. During the rough machining process, the milling speed is controlled at 25m / min, the feed rate is controlled at 0.08mm / z, the milling width is controlled at 2mm, and the milling depth is controlled at 0.5mm;

[0038] Step three, vacuum stress relief annealing is performed on the rough-machined TC4 titanium alloy profile, and vacuum stress relief annealing is performed simultaneously with vacuum shaping. Fix the rough-machined TC4 titanium alloy profile obtained in step two on a special shaping mold, and ensure that the reference surface of the special shaping mold is parallel to the bottom surface of the TC4 titanium alloy profile. Preheat the vacuum heat treatment furnace at 450°C for 30 minutes, set the stress relief annealing temperature at 660°C, and load the fixed profile and shaping mold after reaching the temperature. Keep warm for 60 minutes. After vacuum shaping, the profile is cooled with the furnace to below 280°C and then taken out of the furnace. Air-cool it to below 50°C and then remove the special shaping mold.

[0039] Step 4. Program the finishing process according to the shape of the part. Finish mill each surface of the TC4 titanium alloy profile to the theoretical size. Perform semi-finishing according to the basic structure of the part and remove the process boss. The allowance after semi-finishing is controlled at 0.5mm. After semi-finishing is completed, perform finishing to the theoretical shape. During the semi-finishing and finishing process, a symmetrical processing method is used to evenly remove the allowance on both sides of the TC4 titanium alloy profile to ensure that the part releases stress evenly to both sides along the symmetry line. During the semi-finishing and finishing process, the milling speed is controlled at 20m / min, the feed rate is controlled at 0.04mm / z, the milling width is controlled at 1mm, and the milling depth is controlled at 0.2mm.

[0040] Example 2:

[0041] The target typical part material grade is TC4, with a "T"-shaped cross-section. The wall thickness of the vertical side and bottom side of the typical TC4 titanium alloy T-profile part is 4.5mm±0.5mm. The specific machining steps are as follows:

[0042] Step 1: Prepare a TC4 titanium alloy thick-wall T-shaped profile with a T-shaped cross section (the wall thickness of the vertical and bottom sides of the TC4 titanium alloy T-shaped profile blank is 10 mm ± 0.5 mm, and the profile length is 2200 mm). The torsion angle around the longitudinal axis of any 300 mm section of the profile is less than 1°, the transverse curvature within any 25 mm width is less than 0.25 mm, and the longitudinal curvature within any 300 mm length is less than 0.65 mm. Proceed to Step 2.

[0043] Step 2: For the fixed-size profile transferred in step 1, perform rough machining process programming according to the part shape. Rough mill the surface of the TC4 titanium alloy profile blank, perform rough machining according to the part shape, set process bosses, and use a symmetrical machining method to evenly remove the excess on both sides of the TC4 titanium alloy profile to ensure that the part releases stress evenly on both sides along the symmetry line, and the single-side allowance is controlled at 2mm. During the rough machining process, the milling speed is controlled at 35m / min, the feed rate is controlled at 0.10mm / z, the milling width is controlled at 3mm, and the milling depth is controlled at 0.8mm;

[0044] Step three, vacuum stress relief annealing is performed on the rough-machined TC4 titanium alloy profile, and vacuum stress relief annealing is performed simultaneously with vacuum shaping. Fix the rough-machined TC4 titanium alloy profile obtained in step two on a special shaping mold, and ensure that the reference surface of the special shaping mold is parallel to the bottom surface of the TC4 titanium alloy profile. Preheat the vacuum heat treatment furnace at 450°C for 30 minutes, set the stress relief annealing temperature at 700°C, and load the fixed profile and shaping mold after reaching the temperature. Keep warm for 45 minutes. After vacuum shaping, the profile is cooled with the furnace to below 280°C and then taken out of the furnace. Air-cool it to below 50°C and then remove the special shaping mold.

[0045] Step 4. Program the finishing process according to the shape of the part. Finish mill each surface of the TC4 titanium alloy profile to the theoretical size. Perform semi-finishing according to the basic structure of the part and remove the process boss. The allowance after semi-finishing is controlled at 0.8mm. After semi-finishing is completed, perform finishing to the theoretical shape. During the semi-finishing and finishing process, a symmetrical processing method is used to evenly remove the allowance on both sides of the TC4 titanium alloy profile to ensure that the part releases stress evenly to both sides along the symmetry line. During the semi-finishing and finishing process, the milling speed is controlled at 30m / min, the feed rate is controlled at 0.06mm / z, the milling width is controlled at 2.5mm, and the milling depth is controlled at 0.3mm.

[0046] Example 3:

[0047] The target typical part material grade is TC2, and the cross-section shape is "L"-shaped. The wall thickness of the typical TC2 titanium alloy L-shaped part on both sides is 10.5mm±0.5mm. The specific machining steps are as follows:

[0048] Step 1: Prepare a thick-walled TC2 titanium alloy L-shaped profile with an L-shaped cross-section (the wall thickness of each side of the TC2 titanium alloy L-shaped profile is 16 mm ± 0.5 mm, the angle between the two sides is 104°, and the profile length is 2150 mm). The torsion angle around the longitudinal axis over any 300 mm length is less than 1°, the transverse curvature over any 25 mm width is less than 0.25 mm, and the longitudinal curvature over any 300 mm length is less than 0.65 mm. Proceed to Step 2.

[0049] Step 2: For the fixed-size profile transferred in step 1, perform rough machining process programming according to the shape of the part. Rough mill the surface of the TC2 titanium alloy profile blank, perform rough machining according to the shape of the part, set the process boss, and use a symmetrical machining method to evenly remove the excess on both sides of the TC2 titanium alloy profile to ensure that the part releases stress evenly on both sides along the symmetry line, and the single-side allowance is controlled at 2.5mm. During the rough machining process, the milling speed is controlled at 40m / min, the feed rate is controlled at 0.12mm / z, the milling width is controlled at 4mm, and the milling depth is controlled at 0.8mm;

[0050] Step 3: Perform vacuum stress relief annealing on the rough-processed TC2 titanium alloy profile. Preheat the vacuum heat treatment furnace at 450°C for 30 minutes. Set the stress relief annealing temperature at 750°C. After reaching the temperature, load the profile obtained in step 2 and keep it warm for 60 minutes. After vacuum shaping, cool the profile to below 280°C and then take it out of the furnace and air cool it to room temperature.

[0051] Step 4. Program the finishing process according to the shape of the part. Finish mill each surface of the TC2 titanium alloy profile to the theoretical size. Perform semi-finishing according to the basic structure of the part and remove the process boss. The allowance after semi-finishing is controlled at 1mm. After the semi-finishing is completed, perform finishing to the theoretical shape. During the semi-finishing and finishing process, a symmetrical processing method is used to evenly remove the allowance on both sides of the TC2 titanium alloy profile to ensure that the part releases stress evenly to both sides along the symmetry line. During the semi-finishing and finishing process, the milling speed is controlled at 40m / min, the feed rate is controlled at 0.08mm / z, the milling width is controlled at 3.5mm, and the milling depth is controlled at 0.5mm.

[0052] The above-mentioned embodiment ensures that the internal residual stress of the part is released uniformly and gradually to both sides along the line of symmetry by precisely controlling the milling speed, feed rate, milling width and milling depth during rough machining and fine machining, thereby avoiding the phenomenon of local warping deformation and severe springback caused by the concentrated release of internal residual stress due to improper machining process parameters. For the profiles with "U" and "T" cross sections that do not meet the straightness requirements in step one after rough machining, a shaping mold is used to perform vacuum stress relief annealing + shaping heat treatment. On the one hand, it effectively eliminates the internal residual stress of the profile after rough machining, and on the other hand, it improves the straightness level of the profile before fine machining. After the final fine machining, the profile of the embodiment has low internal residual stress, no machining deformation, small springback, and high part dimensional accuracy.

Claims

1. A method for controlling deformation prevention during machining of titanium alloy thick-walled profiles, characterized in that: The method comprises the following steps: Step 1: Prepare a titanium alloy thick-wall profile of a fixed length ≥ 2000mm, and ensure that the profile straightness meets the following requirements: the torsion angle around the longitudinal axis in any 300mm length should not be greater than 1°, the transverse curvature in any 25mm width should not be greater than 0.25mm, and the longitudinal curvature in any 300mm length should not be greater than 0.65mm; Step 2: Rough machining according to the shape of the part: Rough milling of the titanium alloy profile blank surface, the surface thickness allowance should be greater than 5mm; rough machining is performed according to the part shape, excess material is removed, and process bosses are set as needed; during the rough machining process, the milling speed is controlled between 20m / min and 45m / min, the feed rate is controlled between 0.06mm / z and 0.12mm / z, the milling width is controlled between 1mm and 4mm, and the milling depth is controlled between 0.5mm and 1mm; Step 3: Vacuum stress relief annealing: The rough-machined titanium alloy profile is subjected to vacuum stress relief annealing. The vacuum heat treatment furnace is preheated at 450°C for 30 minutes. The stress relief annealing temperature is set between 650°C and 760°C. After reaching the temperature, the profile obtained in step 2 is loaded and kept at this temperature for 30 minutes to 60 minutes. The profile is cooled with the furnace to below 280°C, then taken out of the furnace and air-cooled to room temperature. Step 4: Finishing according to the shape of the part: Each surface of the titanium alloy profile is finish milled to the theoretical size. The total material removal distribution value of each surface is determined according to the deformation of the part. Semi-finishing is performed according to the basic structure of the part, and the process boss is removed. The allowance after semi-finishing is controlled at 0.5mm~1mm. After semi-finishing is completed, finish machining is performed to the theoretical shape. During semi-finishing and finishing, the milling speed is controlled between 20m / min~40m / min, the feed rate is controlled between 0.04mm / z~0.08mm / z, the milling width is controlled between 1mm~4mm, and the milling depth is controlled between 0.1mm~0.5mm.

2. The method according to claim 1, characterized in that In step 2, rough machining uses a symmetrical machining method to evenly remove the excess on both sides of the titanium alloy profile to ensure that the part releases stress evenly to both sides along the symmetry line, and the single-side allowance is controlled between 1.5mm and 2.5mm.

3. The method according to claim 1, characterized in that When the titanium alloy profile is severely deformed after rough machining, step three vacuum stress relief annealing is carried out simultaneously with vacuum shaping. The rough-machined titanium alloy profile is fixed on the shaping mold to ensure that the reference surface of the shaping mold is parallel to the bottom surface of the titanium alloy profile.

4. The method according to claim 3, characterized in that After vacuum shaping, the profile is cooled to below 280℃ and then taken out of the furnace. After air cooling to below 50℃, the shaping mold is removed.

5. The method according to claim 3, characterized in that Severe deformation means that the straightness requirements of step one are not met.

6. The method according to claim 1, characterized in that Step 4: During the semi-finishing and finishing processes, a symmetrical processing method is used to evenly remove the excess on both sides of the titanium alloy profile to ensure that the part releases stress evenly on both sides along the symmetry line.

7. The method according to claim 1, characterized in that The method is applicable to titanium alloy thick-wall profiles with a wall thickness of 6 mm to 20 mm.

8. The method according to claim 1, characterized in that The method is applicable to medium and low strength titanium alloy profiles.

9. The method according to claim 8, characterized in that The method is applicable to TC1, TC2, TC4, TA15, and TA21.

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