An online residual stress regulation method and device based on laser-ultrasonic coupling

Abstract

The present application belongs to the technical field of stress relief, and particularly relates to an online residual stress regulation method and device based on laser-ultrasonic coupling. The residual stress value of each residual stress regulation unit is obtained after the workpiece to be processed is divided into a plurality of residual stress regulation units; the residual stress regulation unit with the maximum residual stress value is taken as the residual stress regulation unit to be processed; ultrasonic vibration is performed on the entire workpiece to be processed, and laser scanning is performed on the residual stress regulation unit to be processed according to a preset scanning path; after the scanning is completed, the laser and ultrasonic loading are paused, and then the residual stress value of each residual stress regulation unit is reacquired; the above steps are repeated until the residual stress value of each residual stress regulation unit is within a preset residual stress threshold. The present application can dynamically update the laser processing position according to the real-time change of the residual stress in the processing process, avoid local over-processing or under-processing caused by the fixed processing sequence, and realize online closed-loop regulation of the residual stress.

Description

Technical Field

[0001] This invention belongs to the field of stress relief technology, specifically relating to an online residual stress control method and device based on laser-ultrasound coupling. Background Technology

[0002] With the rapid development of the national economy and high-end equipment manufacturing industry, aerospace, shipbuilding and marine engineering, nuclear power pressure vessels, wind turbine towers, rail transportation, and heavy chemical equipment are placing increasingly stringent requirements on the service performance of metal components. Key components in these fields are generally formed using processes such as welding, casting, additive manufacturing, and large-scale machining. During processing, due to uneven plastic deformation, temperature gradients, and differences in phase transformation volume, significant residual tensile stress is inevitably introduced into the components, especially in welds and their heat-affected zones. Residual tensile stress is one of the main factors inducing stress corrosion cracking, fatigue crack initiation, and early component failure, seriously threatening the service life and structural safety of equipment.

[0003] Currently, the main methods used in industry to eliminate or control residual stress include integral annealing heat treatment, vibration aging, mechanical shot peening, and laser shock blasting. Among these, integral annealing heat treatment is a mature and stable process, but it requires the entire component to be placed in a heating furnace for a long period of high-temperature holding. For large welded structures, this presents significant problems such as limited furnace size, huge energy consumption, long holding period, and the risk of overall thermal deformation and degradation of material mechanical properties. Vibration aging equipment is simple, but its efficiency in releasing local high-stress areas of large-rigidity, large-size components is relatively low. Mechanical shot peening and laser shock blasting mainly act on the surface layer and have limited ability to control deep residual stress. Although single continuous laser local annealing scanning can achieve local heating, it relies solely on thermal effects to release stress, which is insufficient for driving dislocation movement, and its control depth and efficiency are limited. In addition, existing local stress control technologies mostly adopt fixed process parameters and open-loop control methods, usually only applying a one-time load based on empirical parameters before treatment, making it difficult to implement zoned control based on differences in residual stress amplitude in different areas. Summary of the Invention

[0004] The purpose of this invention is to provide an online residual stress control device and method based on laser-ultrasound coupling, which achieves efficient control of residual stress and high energy utilization through continuous ultrasonic vibration and single-point laser scanning.

[0005] To achieve the above objectives, this invention provides an online residual stress control method based on laser-ultrasound coupling, comprising the following steps: S1, after dividing the workpiece to be processed into several residual stress control units, obtain the residual stress value of each residual stress control unit; S2, select the residual stress control unit with the largest residual stress value as the current residual stress control unit to be processed; S3, ultrasonic vibration is performed on the entire workpiece to be processed, and laser scanning is performed on the residual stress control unit to be processed according to the preset scanning path; S4. After the scan is completed, pause the laser and ultrasonic loading, and then reacquire the residual stress value of each residual stress control unit. S5. Repeat steps S2 to S4 until the residual stress value of each residual stress control unit is within the preset residual stress threshold.

[0006] Furthermore, in step S3, the workpiece to be processed is fixed on an ultrasonic vibration platform, and then ultrasonic vibration is turned on so that the entire workpiece to be processed is subjected to ultrasonic vibration. After the ultrasonic vibration state stabilizes, the laser scanning is then performed.

[0007] Furthermore, the preset scanning path is a loop path covering the entire area of ​​the residual stress control unit to be processed, and when there is a weld on the workpiece to be processed, the preset scanning path is a loop path perpendicular to the weld direction.

[0008] Furthermore, the laser scanning power is 500-1000 W, the scanning speed is 10-30 mm / s, the scanning interval is 2-4 mm, the ultrasonic vibration frequency is 10-30 kHz, and the ultrasonic vibration power is 50-100 W.

[0009] Furthermore, in step S3, the time for laser scanning of the current wheel for each of the currently processed residual stress control units satisfies the following condition: the maximum attenuation of the residual stress of the current wheel residual stress control unit is less than the difference between its current residual stress value and the preset residual stress threshold.

[0010] Furthermore, the maximum attenuation of the residual stress in the current wheel is 80%-90% of the difference.

[0011] Furthermore, the preset residual stress threshold is 80-120 MPa. In step S2, it is also necessary to determine whether the maximum residual stress value is greater than the preset residual stress threshold. In step S4, before re-acquiring the residual stress value of each residual stress control unit, the temperature of the workpiece to be processed is reduced to meet the residual stress measurement conditions before residual stress detection is performed.

[0012] The present invention also provides an online residual stress control device based on laser-ultrasound coupling, comprising: a continuous laser heating system, an ultrasonic vibration system, an X-ray residual stress online monitoring system, and a path planning module; The ultrasonic vibration system includes an ultrasonic vibration platform, a clamp disposed on the ultrasonic vibration platform, an ultrasonic exciter, and an amplitude transformer. The clamp is used to fix the workpiece to be processed on the ultrasonic vibration platform, and the ultrasonic exciter is used to continuously transmit ultrasonic vibration to the workpiece to be processed on the ultrasonic vibration platform through the amplitude transformer, so as to perform ultrasonic vibration processing on the entire workpiece. The X-ray residual stress online monitoring system is used to monitor the residual stress value of the workpiece to be processed; The path planning module is used to divide the workpiece to be processed into several residual stress control units, select the residual stress control unit with the largest residual stress value, and then plan the laser scanning path of the residual stress control unit with the largest residual stress value. The continuous laser heating system includes a continuous laser and a focusing scanning galvanometer, which emits continuous laser light and, after being modulated by the focusing scanning galvanometer, performs laser scanning on the residual stress control unit with the largest residual stress value according to the laser scanning path.

[0013] Furthermore, the online residual stress control device also includes a temperature monitoring system for monitoring the temperature of the workpiece to be processed, so as to adjust the power of the continuous laser and to allow the online X-ray residual stress monitoring system to determine whether the measurement temperature conditions are met. The X-ray residual stress online monitoring system is also used to monitor the residual stress distribution of the workpiece after each residual stress control unit has been processed.

[0014] Furthermore, the online residual stress control device also includes a control and feedback system for controlling the working status of the continuous laser heating system and the ultrasonic vibration system based on the monitoring results of the online X-ray residual stress monitoring system and the temperature monitoring system.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. This invention utilizes a combined laser and ultrasonic treatment. Continuous laser heating locally heats the control unit with the highest residual stress, reducing the resistance to dislocation movement within the material. Simultaneously, ultrasonic vibration acts on the workpiece, promoting dislocation movement, rearrangement, and the release of residual elastic strain energy within a corresponding temperature window. This synergistic effect of laser and ultrasound enhances the efficiency and depth of residual stress release. As the treatment progresses, the location of the highest residual stress can dynamically change between different control units, avoiding local over- or under-treatment caused by processing in a fixed sequence. Furthermore, starting treatment from the unit with the highest stress, the continuous ultrasonic vibration throughout the process allows units with relatively low residual stress to gradually decrease below the threshold during vibration, thus avoiding further laser heating, reducing energy consumption, and improving the utilization rate of vibration energy.

[0016] 2. This invention divides the area to be treated into multiple control units, and applies laser thermal field and ultrasonic dynamic stress field synergistic treatment only to the local control units where residual stress exceeds the standard, without requiring overall high-temperature annealing of the entire workpiece. It can precisely reduce stress at the location of local residual stress concentration, while other areas are unaffected by high temperatures, effectively avoiding problems such as deformation, grain coarsening, and performance degradation caused by overall workpiece heating, preserving the original mechanical properties of the matrix, and saving energy.

[0017] 3. By limiting the maximum residual stress reduction achievable in a single collaborative processing step to less than the difference between the current stress and the target threshold, each processing step only achieves a limited stress reduction and will not directly reduce the residual stress below the target threshold. Relying on a closed-loop logic of multiple measurement-iteration processing steps to gradually reduce residual stress avoids overprocessing problems caused by excessive processing time / energy in a single step, thus improving the accuracy of residual stress control.

[0018] 4. By limiting the maximum attenuation of the residual stress of the current residual stress control unit to 80%-90% of the difference, the ultrasonic vibration effect when controlling other residual stress control units can be reasonably utilized to continue to eliminate the remaining residual stress exceeding the threshold. Finally, if it is still higher than the residual stress threshold, laser scanning can be used again according to the detection results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an online residual stress control device based on laser-ultrasound coupling according to Embodiment 1 of the present invention; Figure 2 This is the ultrasonic vibration system of Embodiment 1 of the present invention; Figure 3 This invention relates to an online monitoring system for residual X-ray stress in the device. Figure 4 This is a schematic diagram of the control and feedback system of the device of the present invention; Figure 5 This is a process flow diagram of the online residual stress control method of the present invention; Figure 6 This is a schematic diagram of residual stress measurement, processing area division, and laser scanning path in Embodiment 1 of the present invention; Figure 7 This illustrates the influence of different treatment methods on the residual stress distribution and amplitude of titanium alloy welds in Embodiment 1 of the present invention. Figure 8 This is a comparison of the residual stress elimination rate of titanium alloy welds under different treatment methods in Example 1 of the present invention.

[0020] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Control and feedback system, 2-Continuous laser, 3-Focusing scanning galvanometer, 4-Online X-ray residual stress monitoring system, 41-Robotic arm, 42-X-ray stress measuring instrument, 5-Metal workpiece, 6-Ultrasonic vibration system, 61-Ultrasonic exciter, 62-Amplitude bar, 63-Ultrasonic vibration platform, 64-Clamp. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] For combined laser and ultrasound treatment, the energy input, spatial range of action, and optimal loading sequence of the two methods are not the same: excessive laser energy may cause local overheating, tissue softening, or new thermal stress, while excessive ultrasound amplitude may lead to clamping instability or local dynamic damage. Therefore, simply combining the two treatment methods side by side is insufficient to guarantee the efficiency of residual stress release and the uniformity of the stress field after treatment.

[0023] Based on this, the present invention forms a dynamic iterative closed loop through "control unit division, full-area residual stress detection, identification of the unit with the largest residual stress, laser-ultrasonic collaborative processing, full-area residual stress re-measurement, and re-identification of the unit with the largest residual stress". Continuous laser treatment locally heats the control unit with the largest residual stress to reduce the resistance to dislocation movement within the material; ultrasonic vibration acts on the metal workpiece, promoting dislocation movement, rearrangement, and the release of residual elastic strain energy. After each local laser treatment, residual stress is re-detected in all control units, and the next priority unit is determined based on the latest detection results. As the processing progresses, the location of the largest residual stress can dynamically change between different control units, thus avoiding local over- or under-processing caused by processing in a fixed order. Simultaneously, starting processing from the largest control unit, since ultrasonic vibration continues throughout the process, units with relatively small residual stress may gradually decrease below the threshold during vibration, thus avoiding further laser heating treatment, reducing energy consumption, and improving the utilization rate of vibration energy.

[0024] This invention provides an online residual stress control method based on laser-ultrasound coupling, comprising the following steps: S1, after dividing the workpiece to be processed into several residual stress control units, obtain the residual stress value of each residual stress control unit; S2, select the residual stress control unit with the largest residual stress value as the current residual stress control unit to be processed; S3, ultrasonic vibration is performed on the entire workpiece to be processed, and laser scanning is performed on the residual stress control unit to be processed according to the preset scanning path; S4. After the scan is completed, pause the laser scan and ultrasonic vibration, and then reacquire the residual stress value of each residual stress control unit. S5. Repeat steps S2 to S4 until the residual stress value of each residual stress control unit is within the preset residual stress threshold.

[0025] like Figure 1-4 As shown, the present invention provides an online residual stress control device based on laser-ultrasound coupling, including a continuous laser heating system, an ultrasonic vibration system 6, a control and feedback system 1, an X-ray residual stress online monitoring system 4, and a path planning module.

[0026] The ultrasonic vibration system includes an ultrasonic vibration platform, a clamp disposed on the ultrasonic vibration platform, an ultrasonic exciter, and an amplitude transformer. The clamp is used to fix the workpiece to be processed on the ultrasonic vibration platform, and the ultrasonic exciter is used to continuously transmit ultrasonic vibration to the workpiece to be processed on the ultrasonic vibration platform through the amplitude transformer, so as to perform ultrasonic vibration processing on the entire workpiece. The X-ray residual stress online monitoring system is used to monitor the residual stress value of the workpiece to be processed; The path planning module is used to divide the workpiece to be processed into several residual stress control units, select the residual stress control unit with the largest residual stress value, and then plan the laser scanning path of the residual stress control unit with the largest residual stress value. The continuous laser heating system includes a continuous laser and a focusing scanning galvanometer, which emits continuous laser light and, after being modulated by the focusing scanning galvanometer, performs laser scanning on the residual stress control unit with the largest residual stress value according to the laser scanning path.

[0027] The online residual stress control device also includes a temperature monitoring system for monitoring the temperature of the workpiece to be processed, so as to adjust the power of the continuous laser and to allow the online X-ray residual stress monitoring system to determine whether the measurement temperature conditions are met. The X-ray residual stress online monitoring system is also used to monitor the residual stress distribution of the workpiece after each residual stress control unit has been processed.

[0028] The online residual stress control device also includes a control and feedback system 1, comprising a laser control unit, an ultrasonic control unit, a robotic arm control unit, a data acquisition and processing module, and a path planning module. This system controls the operating status of the continuous laser heating system and the ultrasonic vibration system based on the monitoring results from the online X-ray residual stress monitoring system and the temperature monitoring system. The data acquisition and processing module correlates the detection results obtained by the X-ray residual stress measuring instrument with the corresponding control units, compares the residual stress values ​​of each control unit, identifies the control unit with the highest current residual stress value, and determines it as the target for the next round of laser processing.

[0029] Specifically, the ultrasonic vibration system 6 includes an ultrasonic exciter 61, an amplitude transformer 62, an ultrasonic vibration platform 63, and a clamp 64; the continuous laser heating system includes a continuous laser 2 and a focusing scanning galvanometer 3; the metal workpiece 5 is fixed to the upper surface of the ultrasonic vibration platform 63 by the clamp 64; the online X-ray residual stress detection system 4 includes an X-ray residual stress measuring instrument 42 and a robotic arm 41, with the X-ray residual stress measuring instrument 42 located at the end of the robotic arm 41; the continuous laser is emitted by the continuous laser 61, modulated by the focusing scanning galvanometer 3, and incident on the area to be processed of the metal workpiece 5; the ultrasonic vibration system 6 is generated by the ultrasonic exciter 61, transmitted to the ultrasonic vibration platform 63 via the amplitude transformer 61, and then coupled to the metal workpiece 5; By integrating an X-ray residual stress measuring instrument into a robotic arm, the residual stress in the target area can be rapidly measured after laser-ultrasonic processing, achieving closed-loop control of "measurement-control-remeasurement" during the processing and overcoming the limitations of existing technologies.

[0030] The present invention also provides an online residual stress control method based on laser-ultrasonic coupling of the above-mentioned online residual stress control device. Step S1 is implemented by A1 and A2 as described below, step S2 is implemented by A3, step S3 is implemented by A4 and A5, step S4 is implemented by A6, and step S5 is implemented by A7 to A9, as detailed below: A1. Fix the metal workpiece 5 onto the ultrasonic vibration platform using a clamp. Pre-set the size of the control unit according to the size of the area to be treated and the actual processing requirements, and divide the area to be treated into several residual stress control units. A2, the robotic arm drives the X-ray residual stress measuring instrument to detect the set measuring points of all control units in sequence, obtain the initial residual stress value of each control unit, and associate the detection results with the corresponding control unit; A3, the control and feedback system compares the residual stress values ​​of each control unit, determines the control unit with the largest current residual stress value, and takes it as the priority processing unit for this round; A4. Determine the continuous laser scanning path, laser power, scanning speed, scanning interval, number of scans, ultrasonic frequency, ultrasonic amplitude or power, and synergistic action time based on the residual stress value of the current priority processing unit. A5. Start the temperature monitoring system and ultrasonic vibration system. After the metal workpiece reaches a stable ultrasonic vibration state, start the continuous laser heating system to perform laser scanning on the current priority processing unit. Use the local thermal effect of the laser to reduce the resistance to dislocation movement inside the material, and at the same time use the alternating effect of ultrasound to promote dislocation movement and rearrangement, so as to achieve coordinated control of residual stress in the current control unit. A6. After the current priority processing unit completes this round of laser processing, the laser and ultrasonic loading are paused. After the workpiece temperature reaches the X-ray residual stress measurement conditions, the robotic arm drives the X-ray residual stress measuring instrument to re-detect the residual stress of all control units and obtain the latest residual stress value after processing of each control unit. A7. The control and feedback system compares the latest residual stress value of each control unit obtained in step S6 with the set target value: if all control units meet the set requirements, the residual stress control ends; if there are still control units that do not meet the set requirements, the latest residual stress value of each control unit is compared, and the control unit with the largest current residual stress value is re-determined. A8, the maximum residual stress control unit re-determined in step S7 is taken as the next priority processing unit, the ultrasonic vibration is restarted, and the control unit is locally scanned by continuous laser; during this process, the area that has been treated by laser continues to be subjected to ultrasonic vibration along with the metal workpiece. A9. Repeat steps S6 to S8, dynamically updating the laser treatment position through a cyclical process of "full-area residual stress detection - maximum residual stress unit identification - local laser treatment and ultrasonic synergy - full-area re-detection" until the residual stress of all control units reaches the set requirements. Finally, shut down the relevant system, release the clamps, and remove the metal workpiece.

[0031] This invention can solve the problem that in the existing residual stress control process, the treatment position and sequence are fixed in advance, making it difficult to adjust the next treatment position in a timely manner according to the changes in residual stress in each area during the treatment process, thus causing local over-treatment or under-treatment.

[0032] The laser scanning power is 500-1000 W, the scanning speed is 10-30 mm / s, the scanning interval is 2-4 mm, the ultrasonic vibration frequency is 10-30 kHz, and the ultrasonic vibration power is 50-100 W. In step S3, the laser scanning time for each of the currently processed residual stress control units satisfies the following condition: the maximum attenuation of the residual stress in the current wheel is less than the difference between the current residual stress value of the residual stress control unit and the preset residual stress threshold. Thus, a single processing step achieves only a limited stress reduction, preventing the residual stress from directly attenuating below the target threshold. By relying on a closed-loop logic of multiple measurement-iteration processing to gradually reduce residual stress, the overprocessing problem caused by excessive single processing time / energy is avoided, improving the accuracy of residual stress control while fully utilizing vibration energy.

[0033] Specifically, such as Figure 2 As shown, during operation, the metal workpiece 5 is first placed on the ultrasonic vibration platform 63 and clamped and fixed by the fixture 64. The dimensions of the control units are preset according to the size of the area to be processed and the actual processing requirements, and the area to be processed is divided into several control units according to the preset dimensions. Each control unit can use the same size. For the portion of the edge of the area to be processed that is less than a complete control unit, it can be used as an independent control unit or combined with an adjacent control unit.

[0034] Then the online X-ray residual stress detection system 4 is activated, such as... Figure 3 As shown, the robotic arm 41 drives the X-ray residual stress measuring instrument 42 to sequentially detect residual stress in all control units according to pre-set measuring points, and associates the detection results of each measuring point with the corresponding control unit. Each control unit can be set with one or more measuring points; when multiple measuring points are set, the maximum residual tensile stress value detected in the control unit is used as the residual stress evaluation value of the control unit.

[0035] The control and feedback system 1 compares the residual stress evaluation values ​​of all control units, determines the control unit with the highest current residual stress value, and prioritizes it for processing in this round. Based on the location, size, and residual stress level of this control unit, a continuous laser scanning path is planned, and the corresponding laser power, scanning speed, scanning interval, number of scans, ultrasonic frequency, ultrasonic amplitude or power, and collaborative processing time are determined.

[0036] During processing, the ultrasonic vibration system 6 is first activated to bring the metal workpiece 5 into a stable ultrasonic vibration state. Then, the continuous laser heating system is activated to perform a cyclic scan of the currently prioritized processing unit according to a set path. The laser scan time for each currently processed residual stress control unit in the current cycle satisfies the following condition: the maximum attenuation of the residual stress in the currently processed residual stress control unit is less than the difference between the current residual stress value of the currently processed residual stress control unit and the preset residual stress threshold. Specifically, the maximum attenuation of the residual stress in the currently processed residual stress control unit is 80%-90% of the difference.

[0037] After the current priority processing unit completes one laser treatment, it stops continuous laser and ultrasonic vibration loading. Once the workpiece temperature meets the X-ray residual stress measurement conditions, the robotic arm 41 drives the X-ray residual stress measuring instrument 42 to re-detect the residual stress of all control units according to the same measuring points as the initial detection.

[0038] The control and feedback system re-compares the residual stress evaluation values ​​of each control unit based on the results of the full-area retest. If the residual stress of all control units reaches the set target, the processing ends; if there are still control units that have not reached the target, the control unit with the largest residual stress value is re-determined and used as the priority unit for the next round of processing.

[0039] When the newly determined location of the maximum residual stress differs from the previous processing location, the robotic arm 41 and the focusing scanning galvanometer 3 control the continuous laser to transfer to the new control unit for processing. At this time, the ultrasonic vibration system 6 is restarted. During the laser's action on the new control unit, the area that has already undergone laser treatment continues to be subjected to ultrasonic vibration along with the entire metal workpiece 5, allowing for further release of residual stress. Therefore, after a local laser treatment, the relative magnitude of residual stress between control units may continue to change. Thus, this invention updates the next processing location in real time through full-area retesting after each processing round. The theoretical laser processing time can be initially determined based on the residual stress of the current control unit to be processed. During processing, the actual processing time can be set according to a preset proportion of the theoretical laser processing time, allowing the portion exceeding the residual stress threshold to be gradually eliminated in subsequent vibrations.

[0040] If the control unit processed in the previous round still has the largest residual stress value after full-area retesting, then the control unit can continue to be processed by laser-ultrasound synergy in the next round; if the residual stress value of other control units has become the current maximum value, then the process should be transferred to the new control unit with the largest residual stress.

[0041] Repeat the above cycle of "full-area inspection - identification of the maximum residual stress unit - local laser processing and ultrasonic synergy - full-area re-inspection" until the residual stress of all control units meets the set target requirements. Then shut down the relevant system, release the clamp and remove the metal workpiece.

[0042] Furthermore, the upper surface of the ultrasonic vibration platform 63 is provided with a detachable clamp 64, which can be adapted to metal workpieces of different sizes and shapes.

[0043] The focusing scanning galvanometer 3 can realize programmable two-dimensional path scanning of continuous laser in the area to be processed, and adjust the laser scanning position according to the priority processing control unit re-determined in each round.

[0044] The robotic arm 41 can move independently of the laser and ultrasonic system, and within the range allowed by its reachable workspace and X-ray measurement geometry, it can move the X-ray residual stress measuring instrument 42 to the set measuring points and corresponding measuring postures of each control unit.

[0045] Furthermore, the continuous laser scanning area is set within the effective action area of ​​the ultrasonic vibration system to achieve synergistic loading of local laser thermal effect and ultrasonic vibration effect.

[0046] The control and feedback system 1 uses the residual stress evaluation value currently detected by each control unit as the basis for determining the processing priority. After each round of local processing, all control units are re-detected, and the control unit with the largest current residual stress value is selected first for the next round of processing until all control units meet the set target of residual stress.

[0047] The ultrasonic vibration system includes, but is not limited to, a longitudinal wave ultrasonic vibration platform, a flexural wave ultrasonic vibration platform, or a combined longitudinal and flexural ultrasonic vibration platform.

[0048] Example 1 like Figure 5 and 6 Taking a TC4 titanium alloy test plate as an example, the test plate thickness is 3 mm, the weld width is 5 mm, and the weld length is 40 mm. According to the actual processing requirements, the 40 mm long area to be processed is divided into 4 adjacent control units. Each control unit is 10 mm long along the weld length direction and 20 mm wide along the direction perpendicular to the weld.

[0049] A residual stress measurement line perpendicular to the weld length direction is set in the middle of each of the four control units, for a total of four measurement lines; 10 measuring points are set on each measurement line, with an adjacent measuring point spacing of 2 mm, and the measuring points cover the center of the weld and the areas on both sides of the weld, such as... Figure 6 As shown, the robotic arm drives the X-ray residual stress measuring instrument to sequentially complete the residual stress detection at all measuring points, and uses the maximum residual tensile stress value detected by each measuring line as the residual stress evaluation value of the corresponding control unit.

[0050] After the initial test is completed, the control and feedback system compares the residual stress evaluation values ​​of the four control units and selects the control unit with the largest residual tensile stress as the first priority processing unit.

[0051] During processing, the ultrasonic frequency was set to 20 kHz and the ultrasonic power to 80 W. After the ultrasonic vibration stabilized, the continuous laser heating system was started, with the laser power set to 800 W and the scanning speed to 20 mm / s. The laser scanning area of ​​the current priority processing unit is 10 mm × 20 mm, with a scanning length of 10 mm along the weld length direction and a scanning width of 20 mm perpendicular to the weld length direction. The continuous laser scans along the direction perpendicular to the weld length... Figure 6 The laser (indicated by the green arrow) performs a reciprocating scan, moving sequentially along the weld direction at 3 mm scanning intervals, ensuring the laser scanning area covers the weld and its adjacent areas within the control unit. During the laser scanning process, continuous ultrasonic vibration is applied; in this embodiment, the single-round laser-ultrasonic co-processing time is set to 30 minutes.

[0052] After the first round of processing is completed, the continuous laser and ultrasonic vibration systems are turned off. Once the workpiece has cooled to the point where it meets the X-ray residual stress measurement conditions, the residual stress of the four control units is re-measured at all the same measurement points as before processing. Based on the measurement results, the control unit with the highest residual stress is determined and designated as the priority unit for the second round of processing.

[0053] For example, if the residual tensile stress of control unit 1 is the highest before the first round of processing, then control unit 1 will be treated first using a laser-ultrasonic synergistic process. After the first round of processing and re-inspection of the four control units, if the residual tensile stress of control unit 2 becomes the current maximum value, then the laser scanning position will be transferred to control unit 2 in the second round. During the second round of processing, ultrasonic vibration still acts on the entire metal workpiece, so control unit 1, which has already undergone laser treatment, continues to be subjected to ultrasonic vibration, and its residual stress can be further reduced. After the second round is completed, all four control units are inspected again, and the priority processing position for the third round is re-determined based on the new inspection results.

[0054] If, after a full-area retest, the control unit processed in the previous round still has the largest residual tensile stress value, then the control unit will continue to be processed in the next round; if the maximum value is transferred to other control units, then the laser processing position will be changed accordingly.

[0055] In this embodiment, the residual tensile stress evaluation value of each control unit is set to be no higher than 100 MPa as the processing target. After each round of local processing, all four control units are re-tested; if there are still control units with residual tensile stress higher than 100 MPa, the control unit with the highest residual tensile stress is selected to continue the next round of processing; when the residual tensile stress evaluation values ​​of all four control units are no higher than 100 MPa, the entire area to be processed is determined to have reached the residual stress control target and the processing ends.

[0056] Figure 7 The changes in residual stress in the weld were compared under different treatment methods. The parameters for single ultrasonic treatment were: ultrasonic frequency 20 kHz, ultrasonic power 80 W; parameters for single laser heating treatment were: laser power 800 W, scanning speed 20 mm / s, scanning spacing 3 mm; and parameters for laser-ultrasonic coupling treatment were: ultrasonic frequency 20 kHz, ultrasonic power 80 W, laser power 800 W, scanning speed 20 mm / s, and scanning spacing 3 mm. The results show that compared with single ultrasonic or single laser heating treatments, laser-ultrasonic coupling treatment achieves a more significant reduction in residual tensile stress. Figure 8 The residual stress elimination rate shown further indicates that the residual stress control effect of laser-ultrasound coupling treatment is better than that of single laser heating or single ultrasound treatment.

[0057] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for online residual stress control based on laser-ultrasound coupling, characterized in that, Includes the following steps: S1, after dividing the workpiece to be processed into several residual stress control units, obtain the residual stress value of each residual stress control unit; S2, select the residual stress control unit with the largest residual stress value as the current residual stress control unit to be processed; S3, ultrasonic vibration is performed on the entire workpiece to be processed, and laser scanning is performed on the residual stress control unit to be processed according to the preset scanning path; S4. After the scan is completed, pause the laser scan and ultrasonic vibration, and then reacquire the residual stress value of each residual stress control unit. S5. Repeat steps S2 to S4 until the residual stress value of each residual stress control unit is within the preset residual stress threshold.

2. The online residual stress control method based on laser-ultrasound coupling according to claim 1, characterized in that, In step S3, the workpiece to be processed is fixed on an ultrasonic vibration platform, and then ultrasonic vibration is turned on so that the entire workpiece to be processed is subjected to ultrasonic vibration. After the ultrasonic vibration state stabilizes, the laser scanning is performed.

3. The online residual stress control method based on laser-ultrasound coupling according to claim 2, characterized in that, The preset scanning path is a loop path that covers the entire area of ​​the residual stress control unit to be processed. When there is a weld on the workpiece to be processed, the preset scanning path is a loop path perpendicular to the weld direction.

4. The online residual stress control method based on laser-ultrasound coupling according to any one of claims 1-3, characterized in that, In step S3, the time for laser scanning of the current wheel for each of the currently processed residual stress control units satisfies the following condition: the maximum attenuation of the residual stress of the currently processed residual stress control unit is less than the difference between its current residual stress value and the preset residual stress threshold.

5. The online residual stress control method based on laser-ultrasound coupling according to claim 4, characterized in that, The maximum attenuation of the residual stress in the current residual stress control unit is 80%-90% of the difference.

6. The online residual stress control method based on laser-ultrasound coupling according to claim 1, characterized in that, The preset residual stress threshold is 80-120MPa; in step S2, the residual stress control unit with the largest residual stress value greater than the preset residual stress threshold is taken as the current residual stress control unit to be processed.

7. The online residual stress control method based on laser-ultrasound coupling according to claim 1, characterized in that, In step S4, before re-acquiring the residual stress value of each residual stress control unit, the temperature of the workpiece to be processed is reduced to meet the residual stress measurement conditions before residual stress detection is performed.

8. An online residual stress control device based on laser-ultrasonic coupling, characterized in that, include: Continuous laser heating system, ultrasonic vibration system, X-ray residual stress online monitoring system, and path planning module; The ultrasonic vibration system includes an ultrasonic vibration platform, a clamp disposed on the ultrasonic vibration platform, an ultrasonic exciter, and an amplitude transformer. The clamp is used to fix the workpiece to be processed on the ultrasonic vibration platform, and the ultrasonic exciter is used to continuously transmit ultrasonic vibration to the workpiece to be processed on the ultrasonic vibration platform through the amplitude transformer, so as to perform ultrasonic vibration processing on the entire workpiece. The X-ray residual stress online monitoring system is used to monitor the residual stress value of the workpiece to be processed; The path planning module is used to divide the workpiece to be processed into several residual stress control units, select the residual stress control unit with the largest residual stress value, and then plan the laser scanning path of the residual stress control unit with the largest residual stress value. The continuous laser heating system includes a continuous laser and a focusing scanning galvanometer, which emits continuous laser light and, after being modulated by the focusing scanning galvanometer, performs laser scanning on the residual stress control unit with the largest residual stress value according to the laser scanning path.

9. The online residual stress control device based on laser-ultrasonic coupling according to claim 1, characterized in that, The online residual stress control device also includes a temperature monitoring system for monitoring the temperature of the workpiece to be processed, so as to adjust the power of the continuous laser and to allow the online X-ray residual stress monitoring system to determine whether the measurement temperature conditions are met. The X-ray residual stress online monitoring system is also used to monitor the residual stress distribution of the workpiece after each residual stress control unit has been processed.

10. The online residual stress control device based on laser-ultrasonic coupling according to claim 9, characterized in that, The online residual stress control device also includes a control and feedback system, used to control the working status of the continuous laser heating system and the ultrasonic vibration system based on the monitoring results of the online X-ray residual stress monitoring system and the temperature monitoring system.

Images