A method, system and apparatus for residual stress relief of metal pipe

Abstract

The application discloses a kind of metal pipe residual stress elimination method, system and device, method includes: S1 obtains residual stress data and judges high stress area;S2 is sequentially carried out local stress elimination processing to each high stress area, calculates local stress release rate until switching area after reaching standard;S3 carries out overall collaborative stress processing, applies stepwise hydraulic overload and synchronously applies adaptive rotary vibration;S4 real-time monitoring overall processing index, judge whether to meet three termination conditions;S5 pressure relief and low-temperature heat treatment are carried out.The system includes stress mapping module, local processing module, overall processing module, monitoring control module and post-processing module.The device includes clamping and rotating mechanism, hydraulic loading mechanism, exciter, excitation ring, distributed optical fiber sensor and controller.The application can identify high stress area one by one, and adaptively make processing parameters always match the real-time state of pipe, ensure that stress is uniformly released, and effectively eliminate pipe residual stress.

Description

Technical Field

[0001] This invention relates to the field of metallic materials, and in particular to a method, system, and apparatus for eliminating residual stress in metal pipes. Background Technology

[0002] Hydraulic pipes for large-scale engineering machinery require extremely high dimensional and shape precision, and are currently primarily produced using cold-drawn pipes. The production of cold-drawn pipes for hydraulic supports in my country is gradually increasing. During the cold-forming process, uneven plastic deformation generates significant residual stress within the pipe. This residual stress not only affects the dimensional stability of the pipe but can also lead to stress corrosion cracking, reduced fatigue life, and other problems, severely impacting the pipe's performance and reliability. Traditional methods for eliminating residual stress mainly include heat treatment annealing, mechanical vibration aging, and hydraulic bulging. However, these methods have the following shortcomings:

[0003] Heat treatment annealing: High energy consumption, long cycle, and high temperature treatment may change the microstructure and mechanical properties of the pipe. It is not suitable for pipes with special performance requirements (such as high-strength steel pipes and precision alloy pipes).

[0004] Mechanical vibration aging: It has poor adaptability to complex stress distribution, makes it difficult to accurately treat local high stress areas, and the vibration parameters are usually fixed, making it impossible to respond to dynamic adjustments in real time, resulting in unstable treatment effects.

[0005] Hydraulic bulging: Although it can release some stress through plastic deformation, single hydraulic loading cannot eliminate the unevenness of axial and circumferential stress, and lacks control over the deformation of the pipe, which can easily lead to pipe bending or instability. Summary of the Invention

[0006] In view of this, the present invention provides a residual stress elimination method and system capable of accurately identifying high-stress areas, adaptively adjusting processing parameters, considering both local and overall stress elimination, and monitoring the processing effect in real time, thereby overcoming the shortcomings of the prior art. This application adopts the following technical solution: A method for eliminating residual stress in metal pipes includes the following steps: S1: Obtain the residual stress data of the pipe to be tested, and determine whether there is a high stress area based on the preset threshold. If there is, proceed to step S2; if not, proceed directly to step S3. S2: Perform local stress relief treatment on each high-stress area sequentially until all high-stress areas have been treated. The local stress relief treatment includes: S20: Local adaptive pre-relaxation treatment is applied to high-stress areas; S21: Apply initial hydraulic pressure With initial rotation; S22: Real-time monitoring of mechanical response signals, and adaptive adjustment of loading strategies and vibration parameters based on mechanical response signals; S23: Calculate the local stress release rate of this area until the first target value is reached, then switch to the next high-stress area; S3: Perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall coordinated stress treatment includes applying stepped hydraulic overload and simultaneously applying adaptive rotational vibration. S4: Monitor the overall processing indicators in real time and determine whether the three preset termination conditions are met simultaneously; if they are met, proceed to step S5; if not, continue to step S3. S5: Stop loading, depressurize and drain the liquid, and perform low-temperature heat treatment on the pipe to complete stress relief.

[0007] Preferably, in step S1, the residual stress data is obtained mainly by using a distributed fiber optic sensor to perform full-domain stress mapping on the cold-drawn tube, and based on the Brillouin frequency shift variation. Calculate the strain values ​​at each test point Then calculate the stress value according to Hooke's Law. ,in The elastic modulus of the pipe is used to identify continuous areas where the stress value exceeds a preset threshold as high-stress areas.

[0008] Preferably, in the local adaptive pre-relaxation process of step S20, the processing parameters are based on the initial stress gradient of the high-stress region. Set the initial vibration frequency. With initial stress gradient satisfy:

[0009] in: This is a preset proportional coefficient. It is defined as the difference between the maximum and minimum stresses within the region divided by the length of the region.

[0010] Preferably, the mechanical response signal in step S22 includes at least stress-strain signals and vibration spectrum signals. The adaptive adjustment of loading strategy and vibration parameters is based on the real-time monitored mechanical response signal and dynamically optimized through a closed-loop control algorithm to adjust hydraulic pressure P, rotational speed ω, vibration frequency f, and amplitude a, so as to reduce the local stress fluctuation amplitude. Maintain within the preset range.

[0011] Preferably, the stepped hydraulic overload in step S3 refers to the hydraulic pressure gradually increasing to the target overload pressure value in a predetermined stepped manner. Each pressure step has a preset holding time, and the adaptive rotational vibration includes adaptive adjustment of rotational speed and adaptive adjustment of excitation frequency, and synchronous frequency sweep vibration is performed within each pressure step.

[0012] Preferably, the target overload pressure value The following formula is used to calculate the yield strength of the pipe based on its geometric dimensions and material yield strength:

[0013] in: For the material's yield strength, For pipe wall thickness, This refers to the outer diameter of the pipe.

[0014] Preferably, the three termination conditions in step S4 include: Overall stress uniformity index: ,in: , This represents the maximum stress across the entire pipe. This represents the average stress across the entire pipe. The target value; Peak residual stress: ,in: This represents the maximum residual stress at various points on the pipe after treatment. The target stress value; Pipe deformation control indicators: ,in: This represents the maximum deflection of the pipe during the overall processing. The target deflection.

[0015] Preferably, the present invention also provides a residual stress relief system for metal pipes, comprising: The stress mapping module is used to acquire the global residual stress data of the pipe under test and identify whether there are high stress areas. A local processing module is used to perform local stress relief processing on each identified high-stress area in sequence. The local processing module includes: a pre-relaxation unit for performing local adaptive pre-relaxation processing on the high-stress area; a loading unit for applying initial hydraulic pressure and initial rotation; a local control unit for monitoring the mechanical response signal in real time and adaptively adjusting the loading strategy and vibration parameters; and a release rate judgment unit for calculating the local stress release rate and controlling the switch to the next high-stress area. The overall processing module is used to perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall processing module includes: a hydraulic loading unit for applying stepped hydraulic overload; and a rotary vibration unit for synchronously applying adaptive rotary vibration. The monitoring and control module is used to monitor the overall processing indicators in real time and determine whether the three preset termination conditions and the post-processing module are met simultaneously. It is used to stop loading, depressurize and drain the liquid, and perform low-temperature heat treatment on the pipe.

[0016] Preferably, the stress mapping module includes a distributed optical fiber sensor, which is deployed on the surface of the pipe to collect Brillouin frequency shift signals.

[0017] Preferably, the present invention also provides a residual stress relief device for metal pipes, including a guide rail and a support frame. Two support frames are mounted on the guide rail, and a clamping and rotating mechanism is provided on one side of one of the support frames. The pipe to be tested is placed between the two support frames. A hydraulic loading mechanism is also provided on one side of the guide rail. The hydraulic loading mechanism is in communication with the inside of the pipe and is used to apply hydraulic pressure. A vibrator is also provided on the guide rail. The vibrator is also connected to a vibration ring through a connecting rod. The vibration ring is used to wrap the pipe and to apply vibration. A controller is also provided at the front end of the hydraulic loading mechanism.

[0018] The beneficial effects of this invention are as follows: First, through the logical steps provided by this invention, high-stress areas can be identified one by one, and local stress relief treatment can be performed sequentially. After relief, the pipe is subjected to overall coordinated stress treatment. During this process, the overall treatment indicators are monitored in real time to determine whether the three preset termination conditions are met simultaneously. Finally, pressure relief and liquid drainage and low-temperature heat treatment are performed. This method not only ensures the priority release of high-stress areas, but also takes into account the uniformity of stress throughout the entire area. The treatment effect is significantly better than the traditional single method.

[0019] Secondly, in the local stress relief stage, the initial vibration frequency is adaptively set according to the stress gradient of the high-stress area, and the hydraulic pressure P, rotation speed ω, vibration frequency f and amplitude a are optimized in real time through a closed-loop control algorithm, so that the local stress fluctuation amplitude is maintained within the preset range, realizing dynamic matching and significantly improving the efficiency and uniformity of local stress relief.

[0020] Third, the overall treatment stage adopts a combination of stepped hydraulic overload and adaptive rotational vibration. Stepped pressurization causes the pipe to gradually enter the plastic state, while synchronous frequency sweeping vibration excites multiple modes to promote dislocation movement. The two work together to achieve stress uniformity across the entire domain. At the same time, the overall stress uniformity, residual stress peak value, and pipe deformation are used as termination conditions. The treatment ends only when all three conditions are met, ensuring that the treated pipe meets high standards in terms of stress level, uniformity, and geometric accuracy. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of the method of the present invention; Figure 2This is a schematic diagram of the logical flow of the method of the present invention; Figure 3 This is a schematic diagram of the system architecture of the present invention; Figure 4 This is a three-dimensional structural schematic diagram of the device of the present invention; In the diagram: 1. Guide rail; 2. Support frame; 3. Clamping and rotating mechanism; 4. Hydraulic loading mechanism; 5. Exciter; 6. Connecting rod; 7. Excitation ring; 8. Distributed fiber optic sensor; 9. Controller; 10. Stress mapping module; 11. Local processing module; 11. Pre-relaxation unit; 110. Loading unit; 111. Local control unit; 112. Release rate judgment unit; 113. Overall processing module; 12. Hydraulic loading unit; 120. Rotary vibration unit; 121. Monitoring and control module; 13. Post-processing module; and 14. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0023] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Example 1: See Figures 1-2 A method for eliminating residual stress in metal pipes includes the following steps: S1: Obtain the residual stress data of the pipe to be tested, and determine whether there is a high stress area based on the preset threshold. If there is, proceed to step S2; if not, proceed directly to step S3. S2: Perform local stress relief treatment on each high-stress area sequentially until all high-stress areas have been treated. The local stress relief treatment includes: S20: Local adaptive pre-relaxation treatment is applied to high-stress areas; S21: Apply initial hydraulic pressure With initial rotation; S22: Real-time monitoring of mechanical response signals, and adaptive adjustment of loading strategies and vibration parameters based on mechanical response signals; S23: Calculate the local stress release rate of this area until the first target value is reached, then switch to the next high-stress area; S3: Perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall coordinated stress treatment includes applying stepped hydraulic overload and simultaneously applying adaptive rotational vibration. S4: Monitor the overall processing indicators in real time and determine whether the three preset termination conditions are met simultaneously; if they are met, proceed to step S5; if not, continue to step S3. S5: Stop loading, depressurize and drain the liquid, and perform low-temperature heat treatment on the pipe to complete stress relief.

[0025] This embodiment 1 provides a method for eliminating residual stress in metal pipes, which involves, as follows: Figure 4 The device shown is implemented, and employs, as... Figure 3 The system architecture shown below. (The following is combined with...) Figures 1 to 4 The specific implementation process will be explained in detail: First, prepare the pipes to be processed: select Q345B cold-drawn seamless hollow steel pipes (yield strength...). =345 MPa), the specific geometric dimensions are: outer diameter D=50mm, wall thickness T=5mm, length L=2000mm.

[0026] Place the pipe to be tested in such a position as Figure 4 In the device shown: the pipe is mounted between two support frames 2 on the guide rail 1 and clamped and fixed by the clamping and rotating mechanism 3 (including a chuck and a servo motor) on the left support frame 2, while the right support frame 2 is freely supported. A hydraulic loading mechanism 4 is fixed to the left side of the guide rail 1 and communicates with the inside of the pipe through a rotary joint for applying hydraulic pressure. A vibrator 5 (electromagnetic vibrator) is mounted on the guide rail 1 and can move along it. Its front end is connected to a vibration ring 7 via a connecting rod 6, and the vibration ring 7 can open and close to wrap around the pipe. Distributed fiber optic sensors 8 are tightly attached along the pipe's axial direction at 10 mm intervals and connected to a Brillouin optical time domain reflectometer (BOTDR). The controller 9 is an industrial control computer internally configured with the system described in this invention (including a stress mapping module 10, a local processing module 11, an overall processing module 12, a monitoring and control module 13, and a post-processing module 14), and is connected to each actuator and sensor via signal lines.

[0027] Step S1: Acquire residual stress data and identify high-stress areas. Activate controller 9 and stress mapping module 10 to control distributed fiber optic sensor 8 and BOTDR to perform full-area stress mapping on the pipe. Collect the Brillouin frequency shift variation at each measuring point. Converted to strain based on calibration curve Then according to Hooke's Law Calculate the stress value (E = 206 GPa). Generate a global stress distribution map, setting a preset threshold of 0.6. = 207 MPa. Assume two high-stress regions are identified: Region A: 300~450 mm from the left end, 150 mm in length, maximum stress 280 MPa, minimum stress 150 MPa; Region B: 1200~1300 mm from the left end, 100 mm in length, maximum stress 260 MPa, minimum stress 140 MPa; Due to the presence of high-stress areas, proceed to step S2, where local stress relief treatment is performed on areas A and B in sequence.

[0028] Step S2: Local stress relief treatment, first treating area A. Controller 9 controls the vibrator 5 to move along the guide rail 1, causing the excitation ring 7 to move to the position of area A and hug and wrap the pipe. At the same time, the clamping and rotating mechanism 3 drives the pipe to rotate at a low speed (initial speed ω=10rpm).

[0029] In some embodiments, during the local adaptive pre-relaxation process in step S20, the processing parameters are based on the initial stress gradient of the high-stress region. Set the initial vibration frequency. With initial stress gradient satisfy:

[0030] in: This is a preset proportional coefficient. It is defined as the difference between the maximum and minimum stresses within the region divided by the length of the region.

[0031] Specifically, the pre-relaxation unit 110 of the local processing module 11 sets the initial vibration frequency according to the stress gradient of region A, and region A is processed as follows: Calculate the stress gradient: =(280-150) / 0.15 = 867 MPa / m, take the proportionality coefficient K = 0.5 Hz·m / MPa, and set the initial vibration frequency. =433 Hz. The pre-relaxation unit 110 controls the exciter 5 to vibrate region A at 433 Hz and 0.05 mm amplitude for 30 seconds to achieve pre-relaxation; S21: Applying initial hydraulic pressure and initial rotation: Loading unit 111 controls hydraulic loading mechanism 4 to apply initial hydraulic pressure to the inside of the pipe. = 10 MPa, while the clamping and rotating mechanism 3 maintains the pipe at 10 rpm rotation, the rotation speed ω = 10 rpm.

[0032] S22: Real-time monitoring and adaptive control: The local control unit 112 acquires stress-strain signals and vibration spectrum signals in real time through distributed fiber optic sensors 8 and vibration accelerometers (which can be integrated into the excitation ring 7). A PID closed-loop control algorithm is adopted, based on the local stress fluctuation amplitude... The goal was to maintain the hydraulic pressure P, rotational speed ω, vibration frequency f, and amplitude a within a preset range of ±5 MPa. The control process data are shown in Table 1. Table 1. Data on the regulation process

[0033] S23: Stress Release Rate Judgment: The stress release rate judgment unit 113 calculates the local stress release rate in real time. The local stress release rate is calculated as (initial σmax - current σmax) / initial σmax. When the release rate reaches the first target value of 80%, the processing of the current area is stopped. After about 5 minutes, the stress at the center point of area A drops to 52 MPa, with a release rate of 81.4%, satisfying the condition; switch to area B. Area B: = (260-140) / 0.1 = 1200 MPa / m, = 600 Hz. The treatment steps for region B are the same as for region A. Repeat steps S20-S23 above until region B is completely treated (release rate meets the standard). At this point, all high-stress regions have been treated.

[0034] In some embodiments, the stepped hydraulic overload in step S3 refers to the hydraulic pressure gradually increasing to the target overload pressure value in a predetermined stepped manner. Each pressure step has a preset holding time, and the adaptive rotational vibration includes adaptive adjustment of rotational speed and adaptive adjustment of excitation frequency, and synchronous frequency sweep vibration is performed within each pressure step.

[0035] In some embodiments, the target overload pressure value The following formula is used to calculate the yield strength of the pipe based on its geometric dimensions and material yield strength:

[0036] in: For the material's yield strength, For pipe wall thickness, This refers to the outer diameter of the pipe.

[0037] Specific implementation process: Overall coordinated stress treatment: After all high-stress areas have been treated, the excitation ring 7 is moved to the middle of the pipe to enter the overall treatment stage.

[0038] Target overload pressure calculation: according to the formula =σ s·2T / D=345×2×5 / 50=69MPa.

[0039] Stepped hydraulic loading: The hydraulic pressure starts from 0 and gradually increases to 69 MPa in 10 MPa steps, holding each step for 2 minutes, with the final step of 69 MPa held for 5 minutes, at a pressure increase rate of 5 MPa / s; Synchronous adaptive rotary vibration: The rotary vibration unit 121 synchronously controls the clamping rotary mechanism 3 and the vibrator 5 to perform adaptive rotary vibration. Within each pressure holding step, the vibrator 5 performs frequency sweep vibration (frequency linearly increases from 20 Hz to 200 Hz, sweep time 2 minutes), while adaptively adjusting the rotation speed (10~60 rpm) according to the real-time spectrum response to excite the optimal vibration mode of the pipe.

[0040] During the overall processing, the monitoring and control module 13 collects full-area stress data and pipe deflection in real time through distributed fiber optic sensors 8 and laser displacement sensors (which can be installed on guide rail 1, not shown in the figure).

[0041] In some embodiments, the three termination conditions in step S4 include: The overall stress uniformity index is: ,in: , This represents the maximum stress across the entire pipe. This represents the average stress across the entire pipe. The target value; The peak residual stress is: ,in: This represents the maximum residual stress at various points on the pipe after treatment. The target stress value; The pipe deformation control index is as follows: ,in: This represents the maximum deflection of the pipe during the overall processing. The target deflection.

[0042] Specifically, preset target value It is 1.2. 0.2σ s =69MPa, It is 0.5mm / m (corresponding to a total deflection of ≤1.0mm for a 2m pipe).

[0043] At the 16-minute mark (69MPa holding pressure stage), the measured data were as follows: =28MPa =27MPa, CU=1.04≤1.2; σre,max=28MPa ; δ=0.30mm≤1.0mm; When all three conditions are met, the monitoring and control module 13 triggers step S5 to stop loading: shutting down the hydraulic pump station, stopping the vibrator, and stopping the rotating mechanism.

[0044] Step S5: Depressurization and low-temperature heat treatment. Open the drain valve to drain the hydraulic oil inside the pipe back into the oil tank. Drainage time is 30 seconds.

[0045] Specifically, the post-processing module 14 controls the hydraulic loading mechanism 4 to stop pressurizing and open the drain valve to drain the hydraulic oil inside the pipe back to the oil tank (drainage time 30 seconds). The vibrator 5 and the clamping rotation mechanism 3 stop operating. Subsequently, the pipe is transferred to a low-temperature oven (not shown in the figure) and held at 120°C for 2 hours for low-temperature heat treatment. It is then cooled to room temperature with the oven to complete stress relief.

[0046] Low-temperature heat treatment: Transfer the pipe to a low-temperature oven, keep it at 120°C for 2 hours, and then cool it to room temperature with the oven.

[0047] Comparative experimental data: To verify the effectiveness of the method of this invention, a comparative experiment was conducted using Q345B cold-drawn seamless steel pipes (outer diameter 50 mm, wall thickness 5 mm, length 2000 mm) from the same batch. The pipes were randomly divided into three groups of 10 pipes each, and different residual stress relief methods were applied to each group. Control group A: The conventional heat treatment annealing process was used, which involved heating to 550℃ and holding for 2 hours, followed by furnace cooling.

[0048] Control group B: The conventional hydraulic bulging process was used, pressurizing to 60 MPa in one go, holding the pressure for 5 minutes, and then depressurizing.

[0049] Experimental Group C: The method and system described in Example 1 of this invention were used, with the same parameters as in Example 1.

[0050] After processing, various indicators were tested, and the average values ​​of each group were taken. The results are shown in Table 2. Table 2. Data from the control experiment

[0051] Results analysis: 1. Residual stress elimination effect: The average residual stress in experimental group C after treatment was only 42 MPa, significantly lower than that in control group A (65 MPa) and control group B (96 MPa), and CU=1.12, indicating a more uniform stress distribution and no local stress concentration. This invention achieves more thorough stress elimination through synergistic treatment of local and overall stress.

[0052] 2. Deformation control: The maximum deflection of experimental group C was 1.2 mm, which was much smaller than that of the control group (2.8 mm and 3.6 mm). This indicates that the deformation index among the three termination conditions effectively controlled the deformation of the pipe under high pressure and vibration, and ensured dimensional accuracy.

[0053] 3. Other performance indicators are shown in Table 2 and will not be analyzed here. It can be seen that the method of the present invention is superior to traditional heat treatment and hydraulic bulging methods in terms of residual stress elimination effect, stress uniformity, deformation control, mechanical property retention and pass rate.

[0054] See Figure 3 In some embodiments, the present invention also provides a residual stress relief system for metal pipes, comprising: The stress mapping module 10 is used to acquire the global residual stress data of the pipe to be tested and to identify whether there are high stress areas. The local processing module 11 is used to sequentially perform local stress relief processing on each identified high-stress area. The local processing module 11 includes: a pre-relaxation unit 110, used to perform local adaptive pre-relaxation processing on the high-stress area; a loading unit 111, used to apply initial hydraulic pressure and initial rotation; a local control unit 112, used to monitor the mechanical response signal in real time and adaptively adjust the loading strategy and vibration parameters; and a release rate judgment unit 113, used to calculate the local stress release rate and control the switching to the next high-stress area. The overall processing module 12 is used to perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall processing module 12 includes: a hydraulic loading unit 120 for applying stepped hydraulic overload; and a rotational vibration unit 121 for synchronously applying adaptive rotational vibration. The monitoring and control module 13 is used to monitor the overall processing indicators in real time and determine whether the three preset termination conditions are met simultaneously. The post-processing module 14 is used to stop loading, depressurize and drain liquid, and perform low-temperature heat treatment on the pipe.

[0055] In some embodiments, the stress mapping module 10 includes a distributed optical fiber sensor 8, which is deployed on the surface of the pipe to collect Brillouin frequency shift signals.

[0056] See Figure 4In some embodiments, a residual stress relief device for metal pipes includes a guide rail 1 and a support frame 2. Two support frames 2 are mounted on the guide rail 1, and a clamping and rotating mechanism 3 is provided on one side of one of the support frames 2. The pipe to be tested is placed between the two support frames 2. A hydraulic loading mechanism 4 is also provided on one side of the guide rail 1. The hydraulic loading mechanism 4 is in communication with the inside of the pipe and is used to apply hydraulic pressure. A vibrator 5 is also provided on the guide rail 1. The vibrator 5 is also connected to a vibration ring 7 through a connecting rod 6. The vibration ring 7 is used to wrap the pipe and to apply vibration. A controller 9 is also provided at the front end of the hydraulic loading mechanism 4. The controller 9 is equipped with a residual stress relief system for metal pipes.

[0057] Specifically: As shown in Figure 4, the support frame 2 can slide along the guide rail 1 to adjust the spacing to support the pipe. The clamping and rotating mechanism 3 is installed on the left support frame 2, such as a chuck and a servo motor (power 2kW, speed adjustable from 0-100rpm), to clamp and drive the pipe to rotate. The hydraulic loading mechanism 4 is fixed to the left side of the guide rail 1 to apply hydraulic pressure to the inside of the pipe. The vibrator 5 is an electromagnetic vibrator (frequency 20-500Hz, amplitude 0-2mm, maximum excitation force 500N), installed on the guide rail 1. One end of the connecting rod 6 is connected to the vibrator 5, and the other end is connected to the excitation ring 7. The excitation ring 7 is divided into upper and lower halves, which can hug and wrap the pipe. The inner wall is embedded with polyurethane pads to uniformly transmit the excitation force to the pipe. Distributed fiber optic sensors 8 are arranged along the surface of the pipe at a spacing of 10mm and fixed with adhesive. They are connected to the Brillouin optical time domain reflectometer (BOTDR). The controller 9 is an industrial control computer, which is equipped with the system described above (including stress mapping module 10, local processing module 11, overall processing module 12, monitoring and control module 13, and post-processing module 14). It is connected to each actuator and sensor through signal lines.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for eliminating residual stress in metal pipes, characterized in that, Includes the following steps: S1: Obtain the residual stress data of the pipe to be tested, and determine whether there is a high stress area based on the preset threshold. If there is, proceed to step S2; if not, proceed directly to step S3. S2: Perform local stress relief treatment on each high-stress area sequentially until all high-stress areas have been treated. The local stress relief treatment includes: S20: Local adaptive pre-relaxation treatment is applied to high-stress areas; S21: Apply initial hydraulic pressure With initial rotation; S22: Real-time monitoring of mechanical response signals, and adaptive adjustment of loading strategies and vibration parameters based on mechanical response signals; S23: Calculate the local stress release rate of this area until the first target value is reached, then switch to the next high-stress area; S3: Perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall coordinated stress treatment includes applying stepped hydraulic overload and simultaneously applying adaptive rotational vibration. S4: Monitor the overall processing indicators in real time and determine whether the three preset termination conditions are met simultaneously; if they are met, proceed to step S5; if not, continue to step S3. S5: Stop loading, depressurize and drain the liquid, and perform low-temperature heat treatment on the pipe to complete stress relief.

2. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, In step S1, the residual stress data is mainly obtained by using distributed fiber optic sensors to perform full-domain stress mapping on the cold-drawn tube, and based on the Brillouin frequency shift variation. Calculate the strain values ​​at each test point Then calculate the stress value according to Hooke's Law. ,in The elastic modulus of the pipe is used to identify continuous areas where the stress value exceeds a preset threshold as high-stress areas.

3. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, In the local adaptive pre-relaxation process of step S20, the processing parameters are based on the initial stress gradient of the high-stress region. Set the initial vibration frequency. With initial stress gradient satisfy: in: This is a preset proportional coefficient. It is defined as the difference between the maximum and minimum stresses within the region divided by the length of the region.

4. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, The mechanical response signal in step S22 includes at least stress-strain signals and vibration spectrum signals. The adaptive adjustment of loading strategy and vibration parameters is based on the real-time monitored mechanical response signal and dynamically optimized through a closed-loop control algorithm to adjust hydraulic pressure P, rotational speed ω, vibration frequency f, and amplitude a, so as to minimize local stress fluctuation amplitude. Maintain within the preset range.

5. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, The stepped hydraulic overload in step S3 refers to the hydraulic pressure being gradually increased to the target overload pressure value in a predetermined stepped manner. Each pressure step has a preset holding time, and the adaptive rotational vibration includes adaptive adjustment of rotational speed and adaptive adjustment of excitation frequency, and synchronous frequency sweep vibration is performed within each pressure step.

6. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, The target overload pressure value The following formula is used to calculate the yield strength of the pipe based on its geometric dimensions and material yield strength: in: For the material's yield strength, For pipe wall thickness, This refers to the outer diameter of the pipe.

7. The method for eliminating residual stress in metal pipes according to claim 1, characterized in that, The three termination conditions in step S4 include: The overall stress uniformity index is: ,in: , This represents the maximum stress across the entire pipe. This represents the average stress across the entire pipe. The target value; The peak residual stress is: ,in: This represents the maximum residual stress at various points on the pipe after treatment. The target stress value; The pipe deformation control index is as follows: ,in: This represents the maximum deflection of the pipe during the overall processing. The target deflection.

8. A residual stress relief system for metal pipes, characterized in that, include: The stress mapping module is used to acquire the global residual stress data of the pipe under test and identify whether there are high stress areas. A local processing module is used to perform local stress relief processing on each identified high-stress area in sequence. The local processing module includes: a pre-relaxation unit for performing local adaptive pre-relaxation processing on the high-stress area; a loading unit for applying initial hydraulic pressure and initial rotation; a local control unit for monitoring the mechanical response signal in real time and adaptively adjusting the loading strategy and vibration parameters; and a release rate judgment unit for calculating the local stress release rate and controlling the switch to the next high-stress area. The overall processing module is used to perform overall coordinated stress treatment on pipes that have completed local stress relief treatment or have no high stress areas. The overall processing module includes: a hydraulic loading unit for applying stepped hydraulic overload; and a rotary vibration unit for synchronously applying adaptive rotary vibration. The monitoring and control module is used to monitor the overall processing indicators in real time and determine whether the three preset termination conditions are met simultaneously. The post-processing module is used to stop loading, depressurize and drain the liquid, and perform low-temperature heat treatment on the pipe.

9. A residual stress relief system for metal pipes according to claim 8, characterized in that, The stress mapping module includes a distributed optical fiber sensor, which is deployed on the surface of the pipe to collect Brillouin frequency shift signals.

10. A device for relieving residual stress in metal pipes, characterized in that, The device includes a guide rail and support frames. Two support frames are mounted on the guide rail, and one of the support frames has a clamping and rotating mechanism on one side. The pipe to be tested is placed between the two support frames. A hydraulic loading mechanism is also provided on one side of the guide rail. The hydraulic loading mechanism is connected to the inside of the pipe and is used to apply hydraulic pressure. A vibrator is also provided on the guide rail. The vibrator is connected to a vibration ring through a connecting rod. The vibration ring is used to wrap the pipe and apply vibration. A controller is also provided at the front end of the hydraulic loading mechanism. The controller is equipped with a residual stress relief system for the metal pipe.

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