A method for controlling deformation of aluminum alloy thin plate friction stir welding

Abstract

The present invention belongs to the technical field of stir friction welding deformation control, and discloses a method for stir friction welding deformation control of aluminum alloy thin plates. The present invention performs preliminary setting of suitable parameters by constructing a thickness-suitable parameter mapping relationship, and then corrects the suitable parameters according to the angular deformation and arch height of the actual welding process, thereby improving the adaptability of the parameters to the actual welding conditions, timely suppressing deformation fluctuations, ensuring accurate matching of welding parameters, and improving deformation control accuracy. The present invention reduces the lag of path control and improves the response speed to lateral offset of the weld by dynamically setting the position of the welding path control point and generating the path adjustment direction in real time. It can also accurately correct the welding trajectory based on real-time offset data, ensure that the weld direction is consistent with the theory, and improve the welding forming accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of friction stir welding deformation control and relates to a method for controlling deformation of aluminum alloy thin plate friction stir welding. Background Art

[0002] Friction stir welding, as a solid-state joining technology, offers advantages in aluminum alloy welding, such as low heat input and minimal residual stress. However, for thin sheets, such as aluminum alloys, the welding process is prone to angular distortion, arching, and weld offset, leading to dimensional deviations. Therefore, monitoring and controlling distortion during friction stir welding of aluminum alloy sheets is of great significance.

[0003] There are also technical solutions for controlling stir friction welding deformation in the existing technology. For example, the Chinese invention patent application for a predictive control method and system for stir friction welding deformation with publication number CN119282354A includes: inputting the diameter of the stirring needle and the shaft shoulder into the thermal deformation function to obtain the shrinkage difference value, and determining the welding warpage amount based on this and the thickness and length of the part, and predicting the weld deformation amount in combination with the dimension chain. By adjusting the pad height and the pre-deformation of the fixture, the cooling deformation and the pre-deformation are offset, thereby improving the part flatness, production efficiency and welding quality.

[0004] Another Chinese invention patent application, publication number CN107414281A, for a device and method for reducing friction stir welding deformation, includes: a device comprising a workbench, a water-cooling circulation device, a stirring head, a machine head, and a gas cooling device. The water-cooling circulation device cools the back of the workpiece, while the gas cooling device cools the weld area on the front of the workpiece. This dual cooling method accelerates workpiece cooling, solves post-weld deformation problems, and reduces residual stress. The device has a simple structure and is easy to operate.

[0005] Although the above two schemes have proposed some solutions for stir friction welding deformation control, they still have certain limitations. For example: on the one hand, the existing technical solutions lack the analysis and control of the stirring head parameters during friction welding, ignore the mapping construction between thickness and appropriate parameters and the dynamic correction mechanism, resulting in the inability to control the rotation speed and movement speed in real time according to the angular deformation, thereby reducing the deformation control effect.

[0006] On the other hand, the existing technical solutions lack real-time path adjustment function and ignore the dynamic monitoring of the lateral offset of the weld and the absolute lateral offset on both sides. The lack of this path adjustment mechanism makes it impossible to generate accurate adjustment directions based on real-time offset data, and it is impossible to dynamically set the control point position, which ultimately causes the welding path to deviate from the theoretical trajectory and reduces the weld forming accuracy. Summary of the Invention

[0007] In view of this, in order to solve the problems raised in the above background technology, a method for controlling deformation of aluminum alloy thin plate friction stir welding is proposed.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A method for controlling deformation of aluminum alloy thin plate stir friction welding, comprising: obtaining the target thin plate thickness, and then matching it with a preset thickness-appropriate parameter mapping relationship to obtain an appropriate rotation speed and an appropriate movement speed.

[0009] Laser displacement sensors and three-dimensional scanning devices are used to monitor the angular deformation and arch height of the welding process, and appropriate parameters are corrected to obtain the corrected rotation speed and corrected moving speed.

[0010] Locate the current welding position and delineate the welded monitoring area and the to-be-welded monitoring area based on the preset monitoring length.

[0011] A three-dimensional scanning device is used to monitor the lateral offset of the weld in the welded monitoring area in real time, and then the position of the welding path control point is dynamically set.

[0012] A three-dimensional scanning device is used to monitor the absolute lateral offset on both sides of the weld in the monitoring area to be welded in real time, and the path adjustment direction is further generated. The path adjustment action is performed based on the dynamically set welding path control point position and path adjustment direction.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention preliminarily sets the appropriate parameters by constructing a thickness-appropriate parameter mapping relationship, and then corrects the appropriate parameters according to the angular deformation and arch height of the actual welding process, thereby improving the adaptability of the parameters to the actual welding conditions, timely suppressing deformation fluctuations, ensuring accurate matching of welding parameters, and improving deformation control accuracy.

[0014] (2) The present invention reduces the lag of path control and improves the response speed to the lateral offset of the weld by dynamically setting the position of the welding path control point and generating the path adjustment direction in real time. It can accurately correct the welding trajectory based on the real-time offset data, ensure that the weld direction is consistent with the theory, and improve the welding forming accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 Schematic diagram of the implementation of the method steps of the present invention.

[0017] Figure 2 A schematic diagram of a division method of a welded monitoring area and a to-be-welded monitoring area corresponding to an embodiment provided by the present invention.

[0018] Reference numerals: 1-monitoring length, 2-target thin plate, 3-welded monitoring area, 4-to-be-welded monitoring area, 5-current welding position. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 efforts are within the scope of protection of the present invention.

[0020] See also Figure 1 As shown, the present invention provides a deformation control method for stir friction welding of aluminum alloy thin plates, including: obtaining the target thin plate thickness, and then matching it with a preset thickness-appropriate parameter mapping relationship to obtain an appropriate rotation speed and an appropriate moving speed of the welding equipment.

[0021] In a preferred embodiment of the present invention, the thickness-suitable parameter mapping relationship is specifically constructed as follows: a large number of friction stir welding tests are performed on thin plates of the same type and any thickness, and the rotation speed and movement speed corresponding to each friction stir welding test are recorded.

[0022] Several deformation monitoring points are set along the weld, and the angular deformation and arch height of each deformation monitoring point are obtained. The angular deformation and arch height of each deformation monitoring point are averaged and calculated to obtain the angular deformation and arch height corresponding to each friction stir welding test.

[0023] The friction stir welding tests were grouped according to the rotation speed and moving speed, and the angular deformation and arch height corresponding to the friction stir welding tests at the same rotation speed and moving speed were averaged to obtain the angular deformation and arch height corresponding to each rotation speed and moving speed.

[0024] The angular deformation and arch height corresponding to each rotational speed and moving speed are sorted from small to large to obtain the angular deformation sorting and arch height sorting, and sorting numbers are generated respectively. Then, the corresponding sorting numbers are used as the adaptation coefficients, and the angular deformation adaptation coefficients and arch height adaptation coefficients corresponding to each rotational speed and moving speed are summed and calculated. The summation results are compared, and the rotational speed and moving speed corresponding to the minimum value are selected as the appropriate rotational speed and appropriate moving speed corresponding to the thin plate of this thickness.

[0025] According to the above steps, a large number of friction stir welding tests are carried out on thin plates of the same type with different thicknesses, and then the appropriate rotation speed and appropriate moving speed corresponding to thin plates of different thicknesses are generated.

[0026] A thickness-appropriate parameter mapping relationship is established based on the appropriate rotation speeds and appropriate moving speeds corresponding to the thin plates of different thicknesses.

[0027] It should be noted that the advantages of constructing the above mapping relationship in the present invention are: 1. Through preliminary experiments, the optimal rotation speed and moving speed are matched for aluminum alloy sheets of different thicknesses, so that the initial appropriate parameters can be directly obtained according to the thickness of the sheet during actual welding, avoiding blind parameter setting.

[0028] 2. Determine appropriate parameters based on a large amount of test data and systematic calculation and analysis, accurately correlate the parameters with the thickness of the thin plate, and improve the adaptability of the initial parameters to the welding conditions.

[0029] 3. Provide reliable initial values ​​for subsequent correction parameters based on real-time data such as angular deformation and arch height during welding, making the entire deformation control process more scientific and effective, thereby more accurately controlling welding deformation and improving welding quality.

[0030] In a preferred embodiment of the present invention, the specific analysis method of the suitable rotation speed and the suitable moving speed is as follows: the target thin plate thickness and each thickness corresponding to the thickness-suitable parameter mapping relationship are subjected to relative difference analysis to obtain a difference index between the target thin plate thickness and each thickness.

[0031] It should be noted that by calculating the difference index of each thickness in the mapping relationship between the target thin plate thickness and the thickness-appropriate parameter, the reference thickness closest to the target thin plate thickness is determined, and then the appropriate welding parameters corresponding to the reference thickness are selected as the initial parameters for welding the target thin plate to ensure the accuracy of the initial parameters.

[0032] It should be noted that the specific method of the relative difference analysis is: the target thin plate thickness and each thickness in the thickness-suitable parameter mapping relationship are difference calculated and then the absolute value is taken, and then the ratio with the target thin plate thickness is calculated to obtain the corresponding difference index.

[0033] The difference indexes are compared, and appropriate parameters corresponding to the thickness mapping of the minimum difference index are selected as the appropriate rotation speed and appropriate moving speed of the current friction stir welding.

[0034] It is important to further explain that the smaller the difference index, the closer the target sheet thickness matches the reference thickness. Therefore, the reference thickness with the smallest difference index is selected, and its corresponding appropriate parameters are used as the initial welding parameters for the target sheet, reducing the blindness of parameter setting.

[0035] Laser displacement sensors and three-dimensional scanning devices are used to monitor the angular deformation and arch height of the welding process, and appropriate parameters are corrected to obtain the corrected rotation speed and corrected moving speed.

[0036] In a preferred embodiment of the present invention, the specific analysis method of the angular deformation and the arch height is as follows: locate the current welding position, and then locate the welding parameter correction influence area based on the preset parameter correction influence distance.

[0037] Based on the equal interval length, several welding reference points are evenly distributed in the area affected by the welding parameter correction to obtain the angular deformation and arch height of the welding end points on both sides corresponding to each welding reference point.

[0038] It is important to explain that within the area affected by the corrected welding parameters, evenly spaced reference points ensure regularity and coverage of data collection. By distributing these points at equal intervals, the continuous weld deformation area is discretized into multiple measurable reference points, making it easier to accurately capture deformation differences at different locations.

[0039] The angular deformation and arch height of the welding end points on both sides corresponding to each welding reference point are averaged to obtain the angular deformation and arch height corresponding to each welding reference point, and the distance from each welding reference point to the current welding position is obtained.

[0040] The distance from each welding reference point to the current welding position and the preset parameter correction influence distance are analyzed for influence degree to obtain the influence weight factor corresponding to each welding reference point.

[0041] It's important to explain that the influence weight factor quantifies the degree of influence of each welding reference point on the deformation of the current welding position. The closer the point is to the current position, the larger the weight factor, and vice versa. The influence of welding deformation generally decreases with distance, so the weight factor is calculated based on the principle that the closer the distance, the higher the influence weight. The weight factor quantifies the difference in the distance's effect on deformation, preventing interference from distant point data on the deformation calculation of the current position. The weight factor directly influences the subsequent weighted fusion of angular deformation and arch height, thereby determining the direction and magnitude of welding parameter corrections.

[0042] The angular deformation and arch height corresponding to each welding reference point are weightedly fused with the corresponding influencing weight factor to obtain the angular deformation and arch height corresponding to the current welding position.

[0043] In a preferred embodiment of the present invention, the specific analysis method of the corrected rotation speed and the corrected moving speed is as follows: the angular deformation and arch height corresponding to the current welding position are respectively compared with the preset angular deformation threshold and arch height threshold to obtain the angular deformation deviation and arch height deviation, and then the mean is calculated to obtain the welding parameter correction coefficient.

[0044] It should be noted that the reasons for choosing angular deformation and arch height as the basis for correction are:

[0045] 1. Both are the most typical deformation forms in friction stir welding of aluminum alloy thin plates. Angular deformation reflects the angular deviation of the plate around the weld axis, while arch height reflects the degree of vertical bulge in the weld area, directly affecting the dimensional accuracy and structural stability of the weld.

[0046] 2. Changes in rotational speed and travel speed directly affect welding heat generation, which is the core factor causing angular deformation and arch height. By monitoring these two indicators in real time, the deformation trend under the current parameters can be accurately reflected, providing a direct basis for parameter correction.

[0047] 3. With the help of laser displacement sensors and three-dimensional scanning devices, both can be measured in real time with high precision, forming a closed-loop control of monitoring, analysis and correction.

[0048] 4. When constructing the thickness-appropriate parameter mapping relationship, a large number of experiments have been conducted to verify the matching of angular deformation and arch height with welding parameters. Its analysis methods such as mean calculation and weight fusion ensure the reliability of the data and make the correction process more scientific.

[0049] The speed correction amount is calculated by multiplying the welding parameter correction coefficient by the preset unit speed adjustment amount, and then the corrected speed is obtained by calculating the difference between the appropriate speed and the speed correction amount.

[0050] The welding parameter correction coefficient is multiplied by the preset unit moving speed adjustment amount to obtain the moving speed correction amount, and then the correction moving speed is obtained by summing the result with the appropriate moving speed.

[0051] It should be noted that the setting basis of the preset unit speed adjustment amount and the preset unit moving speed adjustment amount is: the preset unit speed and moving speed adjustment amount are set based on preliminary experiments, and the benchmark value is determined through a large number of tests and analyses on the impact of unit parameter adjustment on deformation; to match the thermophysical properties of aluminum alloy, the adjustment range is determined according to thermal conductivity, melting point, etc.; considering the thickness gradient of the thin plate, the heat conduction and rigidity differences of different thicknesses affect the adjustment amount; subject to the performance constraints of the welding equipment, the value is set within the adjustment accuracy and range; based on the deformation control accuracy target, the deformation threshold is reversed according to industry standards or product requirements to ensure that the parameter correction is scientific and effective.

[0052] It is necessary to explain the influence of the rotation speed and moving speed on deformation: in the friction stir welding of aluminum alloy thin plates, the rotation speed and moving speed directly affect the deformation by affecting the heat generation. When the rotation speed increases, the friction between the stirring head and the material intensifies, the heat generation increases, and the heat affected zone expands, and the angular deformation and the arch height increase accordingly; conversely, the deformation decreases. Increasing the moving speed will shorten the thermal action time, reduce heat generation, and suppress deformation, but too fast will lead to insufficient welding. The two need to be adjusted in coordination: combining the reduction of the rotation speed with the increase of the moving speed can ensure efficiency while reducing heat generation, achieve precise control of deformation, and improve welding quality.

[0053] It should be noted that the present invention preliminarily sets the appropriate parameters by constructing a thickness-appropriate parameter mapping relationship, and then corrects the appropriate parameters according to the angular deformation and arch height of the actual welding process, thereby improving the adaptability of the parameters to the actual welding conditions, timely suppressing deformation fluctuations, ensuring accurate matching of welding parameters, and improving deformation control accuracy.

[0054] Locate the current welding position, see Figure 2 As shown, the welded monitoring area and the to-be-welded monitoring area are delineated based on the preset monitoring length.

[0055] It should be noted that the welded monitoring area is used to monitor the lateral offset of completed welds and analyze historical deformation trends; the unwelded monitoring area is used to predict the offset of subsequent welds on both sides and plan path adjustments in advance. By dynamically dividing the areas, a closed-loop control system is implemented, combining historical deformation analysis, current parameter correction, and future path prediction. This ensures continuous deformation monitoring and forward-looking path adjustments during the welding process, thereby improving welding accuracy.

[0056] A three-dimensional scanning device is used to monitor the lateral offset of the weld in the welded monitoring area in real time, and then the position of the welding path control point is dynamically set.

[0057] In a preferred embodiment of the present invention, the specific analysis method of the weld lateral offset is as follows: use a three-dimensional scanning device to obtain the weld contour of the welded monitoring area, locate the weld direction, set a number of weld direction monitoring points based on equal intervals, and simultaneously obtain the theoretical weld centerline position.

[0058] The distance between each weld trend monitoring point and the theoretical weld centerline position is obtained, the distance is compared with a preset weld lateral offset threshold, and the weld trend monitoring point whose distance is greater than the preset weld lateral offset threshold is recorded as an abnormal point.

[0059] It should be noted that the threshold for lateral weld offset is set based on the product design accuracy requirements, industry standards, and preliminary experiments conducted on the material properties and thickness of aluminum alloy sheet and friction stir welding process parameters. Extensive testing analyzed the impact of different offsets on weld strength and quality, and a reasonable threshold was set based on equipment accuracy and control capabilities to ensure weld accuracy.

[0060] The distance from each abnormal point to the theoretical weld centerline is averaged to obtain the weld lateral offset.

[0061] In a preferred embodiment of the present invention, the specific analysis method for dynamically setting the welding path control point position is as follows: the weld lateral offset is calculated by ratioing the weld lateral offset with a preset weld lateral offset threshold to obtain the weld lateral offset abnormality.

[0062] The weld lateral offset abnormality is multiplied by the preset welding path control spacing to obtain the welding path control spacing correction amount, and the welding path control spacing and the welding path control spacing correction amount are difference calculated to obtain the corrected welding path control spacing.

[0063] It should be noted that the preset welding path control spacing is determined based on the thickness and material properties of the aluminum alloy sheet and the friction stir welding process parameters. Preliminary experiments analyzed the effect of monitoring the lateral offset of the weld at different spacings, and a baseline value was determined based on the motion accuracy and control response speed of the welding equipment. Furthermore, the industry's requirements for weld formation accuracy were taken into consideration to ensure that the control spacing can both capture offset trends and avoid overcrowding of control points, which can affect welding efficiency, thus achieving a balance between monitoring accuracy and production efficiency.

[0064] The next welding path control point position is located based on the current welding position and the corrected welding path control distance.

[0065] It's important to note that the advantages of dynamically setting the position of welding path control points include: dynamically adjusting the control spacing based on the real-time lateral offset of the weld seam. When the offset is abnormal, the control spacing is automatically reduced, and the control points are denser to increase the frequency of path corrections and accurately respond to weld seam offset trends. Conversely, when the offset is abnormal, the spacing is increased to avoid excessive control that affects efficiency. This mechanism achieves a balance between monitoring accuracy and welding efficiency. By driving the control point layout with real-time data, it enhances adaptability to dynamic deformation during aluminum alloy sheet welding, ensuring that the welding trajectory always adheres to the theoretical path and improving weld formation accuracy.

[0066] A three-dimensional scanning device is used to monitor the absolute lateral offset on both sides of the weld in the monitoring area to be welded in real time, and the path adjustment direction is further generated. The path adjustment action is performed based on the dynamically set welding path control point position and path adjustment direction.

[0067] In a preferred embodiment of the present invention, the specific analysis method of the absolute lateral offset on both sides of the weld is as follows: a three-dimensional scanning device is used to obtain the contours of the target thin plates on both sides of the unwelded monitoring area, the direction of the weld to be welded is located, and a number of lateral offset monitoring points are set based on equal interval lengths.

[0068] Obtain the edge positions of the thin plates on both sides perpendicular to the direction of the weld to be welded corresponding to each lateral offset monitoring point, and at the same time obtain the corresponding theoretical edge positions, obtain the distances between the edge positions of the thin plates on both sides and the corresponding theoretical edge positions, and then perform average calculation to obtain the absolute lateral offsets on both sides of the weld corresponding to each lateral offset monitoring point.

[0069] The absolute lateral offsets on both sides of the weld corresponding to each lateral offset monitoring point are averaged to obtain the absolute lateral offsets on both sides of the weld corresponding to the current welding position.

[0070] In a preferred embodiment of the present invention, the specific analysis method of the generated path adjustment direction is as follows: locating the welding center point corresponding to the current welding position, and locating the theoretical welding center point corresponding to the next direction adjustment point based on the preset direction adjustment distance.

[0071] It should be noted that the setting basis of the preset direction adjustment distance is: the preset direction adjustment distance is set according to the aluminum alloy material and thickness, stir friction welding process parameters, combined with the equipment movement accuracy and response capability, according to the weld design accuracy requirements, and the deviation rate under different adjustment distances is determined through preliminary experiments. The deformation law of similar plates in historical welding data is also referred to to balance accuracy and efficiency.

[0072] The direction in which the welding center point corresponding to the current welding position points to the theoretical welding center point corresponding to the next direction adjustment point is recorded as the path adjustment direction.

[0073] In a preferred embodiment of the present invention, the specific logic of executing the path adjustment action is: performing the path adjustment action based on the current welding position and the path adjustment direction.

[0074] When the welding head performs the friction stir welding operation to the next welding path control point position, it continues to analyze the path adjustment direction corresponding to the next welding path control point position, and performs the path adjustment action, while dynamically setting the welding path control point position analysis until the welding is completed.

[0075] It should be noted that this welding path control method has the advantage of real-time dynamic correction. When the welding head reaches the control point, the analysis is triggered, and the adjustment direction is quickly generated and executed to avoid the accumulation of deviations. Through the monitoring-adjustment-re-monitoring closed loop, the control point position is dynamically set, and the path is accurately controlled to return to the theoretical center. The full automation adapts to the deformation of the entire welding process and reduces manual intervention, which not only improves the accuracy of the welding trajectory, but also ensures quality stability and production efficiency.

[0076] It should be noted that the present invention reduces the lag of path control and improves the response speed to the lateral offset of the weld by dynamically setting the position of the welding path control point and generating the path adjustment direction in real time. It can accurately correct the welding trajectory based on real-time offset data, ensure that the weld direction is consistent with the theory, and improve the welding forming accuracy.

[0077] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, they should all fall within the scope of protection of the present invention.

Claims

1. A method for controlling deformation of aluminum alloy thin plate friction stir welding, characterized in that: include: Obtain the target sheet thickness and match it with the preset thickness-appropriate parameter mapping relationship to obtain the appropriate rotation speed and appropriate movement speed of the welding equipment; Laser displacement sensors and 3D scanning devices are used to monitor the angular deformation and arch height of the welding process, and appropriate parameters are corrected to obtain the corrected rotation speed and corrected moving speed. Locate the current welding position and delineate the welded monitoring area and the to-be-welded monitoring area based on the preset monitoring length; Use a 3D scanning device to monitor the lateral offset of the weld in the welded monitoring area in real time, and then dynamically set the position of the welding path control point; The 3D scanning device is used to monitor the absolute lateral offset of the weld on both sides of the weld in the monitoring area to be welded in real time, and the path adjustment direction is generated. The path adjustment action is performed based on the dynamically set welding path control point position and path adjustment direction; The specific analysis method of the angular deformation and the arch height is as follows: Locate the current welding position, and then locate the welding parameter correction influence area based on the preset parameter correction influence distance; A plurality of welding reference points are uniformly distributed in the area affected by the welding parameter correction based on equal interval lengths, and the angular deformation and arch height of the welding end points on both sides corresponding to each welding reference point are obtained; The angular deformation and arch height of the welding end points on both sides corresponding to each welding reference point are averaged to obtain the angular deformation and arch height corresponding to each welding reference point, and the distance from each welding reference point to the current welding position is obtained; An influence weight factor corresponding to each welding reference point is obtained by analyzing the influence degree of the distance from each welding reference point to the current welding position and the influence distance of the preset parameter correction; The angular deformation and arch height corresponding to each welding reference point are respectively fused with the corresponding influencing weight factor to obtain the angular deformation and arch height corresponding to the current welding position; The specific analysis method of the modified rotation speed and the modified movement speed is as follows: Calculating the relative differences between the angular deformation and the arch height corresponding to the current welding position and the preset angular deformation threshold and the arch height threshold to obtain the angular deformation deviation and the arch height deviation, and then performing mean calculation to obtain the welding parameter correction coefficient; The speed correction value is calculated by multiplying the welding parameter correction coefficient by the preset unit speed adjustment value, and then the corrected speed is obtained by calculating the difference between the appropriate speed and the speed correction value; The welding parameter correction coefficient is multiplied by the preset unit moving speed adjustment amount to obtain the moving speed correction amount, and then the correction moving speed is obtained by summing the result with the appropriate moving speed.

2. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 1, wherein: The specific construction method of the thickness-suitable parameter mapping relationship is as follows: Conduct a large number of friction stir welding tests on thin plates of the same type and any thickness, and record the rotation speed and moving speed corresponding to each friction stir welding test; Several deformation monitoring points are set along the weld seam, and the angular deformation and arch height of each deformation monitoring point are obtained. The angular deformation and arch height of each deformation monitoring point are averaged to obtain the angular deformation and arch height corresponding to each friction stir welding test. The friction stir welding tests were grouped according to the rotation speed and moving speed, and the angular deformation and arch height corresponding to the friction stir welding tests at the same rotation speed and moving speed were averaged to obtain the angular deformation and arch height corresponding to each rotation speed and moving speed; The angular deformation and arch height corresponding to each rotational speed and moving speed are sorted from small to large to obtain an angular deformation sort and an arch height sort, and a sort number is generated respectively. Then, the corresponding sort number is used as an adaptation coefficient. The angular deformation adaptation coefficient and the arch height adaptation coefficient corresponding to each rotational speed and moving speed are summed and calculated. The summed results are compared, and the rotational speed and moving speed corresponding to the minimum value are selected as the appropriate rotational speed and appropriate moving speed corresponding to the thin plate of the thickness; According to the above steps, a large number of friction stir welding tests are carried out on thin plates of the same type with different thicknesses, thereby generating the appropriate rotation speed and suitable moving speed corresponding to thin plates of different thicknesses; A thickness-appropriate parameter mapping relationship is established based on the appropriate rotation speeds and appropriate moving speeds corresponding to the thin plates of different thicknesses.

3. The method for controlling deformation of aluminum alloy sheet friction stir welding according to claim 2, wherein: The specific analysis method of the suitable rotation speed and the suitable moving speed is as follows: Performing relative difference analysis on the target thin plate thickness and each thickness corresponding to the thickness-suitable parameter mapping relationship to obtain a difference index between the target thin plate thickness and each thickness; The difference indexes are compared, and appropriate parameters corresponding to the thickness mapping of the minimum difference index are selected as the appropriate rotation speed and appropriate moving speed of the current friction stir welding.

4. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 1, wherein: The specific analysis method of the weld lateral offset is as follows: Use a three-dimensional scanning device to obtain the weld contour of the welded monitoring area, locate the weld direction, set several weld direction monitoring points based on equal intervals, and obtain the theoretical weld centerline position at the same time; Obtaining the distance between each weld trend monitoring point and the theoretical weld centerline position, comparing the distance with a preset weld lateral offset threshold, and marking the weld trend monitoring point whose distance is greater than the preset weld lateral offset threshold as an abnormal point; The distance from each abnormal point to the theoretical weld centerline is averaged to obtain the weld lateral offset.

5. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 4, wherein: The specific analysis method for dynamically setting the welding path control point position is as follows: The weld lateral offset is calculated by comparing the weld lateral offset with a preset weld lateral offset threshold to obtain a weld lateral offset abnormality; The weld lateral offset abnormality is multiplied by the preset welding path control spacing to obtain a welding path control spacing correction value, and the difference between the welding path control spacing and the welding path control spacing correction value is calculated to obtain a corrected welding path control spacing; The next welding path control point position is located based on the current welding position and the corrected welding path control distance.

6. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 5, wherein: The specific analysis method of the absolute lateral offset on both sides of the weld is as follows: Use a three-dimensional scanning device to obtain the contours of the target thin plates on both sides of the unwelded monitoring area, locate the direction of the weld to be welded, and set several lateral offset monitoring points based on equal intervals; Obtain the edge positions of the thin plates on both sides perpendicular to the direction of the weld to be welded corresponding to each lateral offset monitoring point, and simultaneously obtain the corresponding theoretical edge positions, obtain the distances between the edge positions of the thin plates on both sides and the corresponding theoretical edge positions, and then perform average calculation to obtain the absolute lateral offsets on both sides of the weld corresponding to each lateral offset monitoring point; The absolute lateral offsets on both sides of the weld corresponding to each lateral offset monitoring point are averaged to obtain the absolute lateral offsets on both sides of the weld corresponding to the current welding position.

7. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 6, wherein: The specific analysis method of the generated path adjustment direction is as follows: Locate the welding center point corresponding to the current welding position, and locate the theoretical welding center point corresponding to the next direction adjustment point based on the preset direction adjustment distance; The direction in which the welding center point corresponding to the current welding position points to the theoretical welding center point corresponding to the next direction adjustment point is recorded as the path adjustment direction.

8. The method for controlling deformation of aluminum alloy thin plate friction stir welding according to claim 7, wherein: The specific logic of the execution path adjustment action is: Performing a path adjustment action based on the current welding position and the path adjustment direction; When the welding head performs the friction stir welding operation to the next welding path control point position, it continues to analyze the path adjustment direction corresponding to the next welding path control point position, and performs the path adjustment action, while dynamically setting the welding path control point position analysis until the welding is completed.

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