Welding experiment table for aviation metal component welding performance test and welding stress compliance regulation and control method

Abstract

The invention relates to a welding experiment table for aviation metal component welding performance testing and a welding stress compliance regulation and control method. The welding experiment table comprises a bottom platform, a right side fixed clamping system, a welding clamp and a left side active compliance clamping system. The right side fixed clamping system is integrated with a six-dimensional force sensor, and the left side active compliant clamping system comprises a lower layer compliant driving module and an upper layer workpiece clamping module; the welding experiment table comprises two working modes of a rigid clamping mode and a compliant clamping regulation and control mode, welding stress is collected in real time through a six-dimensional force sensor, a welding stress compliant regulation and control method is designed in combination with the PD controller principle, and the displacement compensation amount is calculated according to the welding force collected in real time; axial displacement adjustment is applied to the clamping end in a servo driving mode, flexible control over welding stress is achieved, the fatigue performance and service reliability of a welded component are fundamentally improved, and a standardized precision guarantee solution independent of experience is provided for aeronautical manufacturing.

Description

Technical Field

[0001] This invention relates to the field of welding fixture technology, and in particular to a welding test bench for testing the welding performance of aerospace metal components and a method for controlling welding stress compliance. Background Technology

[0002] In the aerospace manufacturing field, critical components such as fuselage structures, load-bearing frames, and thin-walled skins typically require welding processes to achieve high-strength connections. As aircraft structures evolve towards lightweighting, high integration, and high reliability, welding quality has become one of the key factors affecting the service performance and safety of aerospace structures.

[0003] Various metallic materials, including aluminum alloys, titanium alloys, high-strength steel, and other aerospace-grade metals, are widely used as load-bearing components in aerospace structures. These aerospace metal components commonly face common problems during welding, such as concentrated heat input, steep temperature gradients, and difficulty in effectively controlling residual stress after welding. Under the influence of localized high-temperature heat sources during welding, metal components inevitably undergo complex thermo-elastic-plastic deformation processes. After cooling, residual deformation and residual stress concentration easily form, leading to engineering problems such as component warping, decreased assembly accuracy, weld performance degradation, and even reduced service life.

[0004] Among the various aerospace metallic materials mentioned above, aerospace aluminum alloy components are the most widely used, and their stress and deformation problems during welding are particularly prominent and representative. Aluminum alloys typically have high thermal conductivity and a high coefficient of linear expansion, while their strength decreases significantly at high temperatures, making them more prone to severe and uneven thermal deformation during welding. This results in more typical post-weld residual stress and deformation problems. Therefore, studying the welding process of aerospace aluminum alloys can effectively reflect the common challenges faced by aerospace metallic welded components in terms of welding stress evolution and deformation control.

[0005] To control the deformation of metal components during welding, large, high-rigidity welding fixtures and test bench systems are commonly used in current engineering practices. These systems typically use mechanical or hydraulic methods to rigidly constrain the workpiece in a preset position, sometimes supplemented by anti-deformation or pre-deformation methods to compensate for welding deformation. However, this type of completely rigid constraint welding strategy has significant limitations. On the one hand, rigid clamping does not fundamentally eliminate welding thermal stress, but rather forcibly suppresses and accumulates it inside the workpiece, easily leading to high residual stress concentration in the heat-affected zone of the weld and the clamping area, thereby reducing the fatigue performance of the welded structure and increasing the risk of stress corrosion cracking. On the other hand, the large welding stress generated during welding will continuously act on the fixture and test bench body, and long-term operation may cause elastic deformation or even creep of the fixture structure, resulting in decreased positioning accuracy and affecting welding consistency and assembly accuracy.

[0006] Furthermore, aerospace metal welded components often exhibit characteristics such as thin walls, low stiffness, and complex structural forms, resulting in significantly nonlinear and condition-sensitive welding deformation behavior. Traditional welding fixtures rely heavily on the experience of process engineers for setting the anti-deformation amount and clamping force, typically requiring multiple trials and adjustments to achieve the desired effect. They lack adaptability to different welding conditions and struggle to meet the high efficiency, high consistency, and high reliability requirements of modern aerospace manufacturing.

[0007] Therefore, with the ever-increasing demands for high precision, high reliability, and high consistency in aerospace manufacturing, the existing welding technology system, which is based on passive rigid constraints, has gradually revealed its technological bottlenecks. The aerospace industry urgently needs a new type of welding process equipment and methods that can break through the traditional passive constraint paradigm and possess active sensing, intelligent decision-making, and precise control capabilities. This would allow for effective control of the macroscopic morphology accuracy of components while improving the internal stress state of welded components from the source, thereby enhancing the overall performance and manufacturing consistency of aerospace metal welded components. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a welding test bench and a method for welding stress compliance control for testing the welding performance of aerospace metal components. During the welding process, the welding test bench can maintain the high rigidity and stability of the component clamping boundary to ensure macroscopic morphology and positioning accuracy. In the post-weld cooling stage after welding, the welding shrinkage stress is released in a controlled compliance manner, realizing active control of welding stress and quantifiable characterization of post-weld deformation. This solves the problems of residual stress concentration, welding shrinkage force overflow damaging tooling, and positioning accuracy failure caused by existing rigid constraint technology, and improves the repeatability and adaptability of the process.

[0009] To achieve the above technical objectives, the present invention provides the following technical solution: a welding test bench for testing the welding performance of aerospace metal components, comprising: The right-side fixed clamping system and the left-side active compliant clamping system are used to clamp the right and left ends of the metal weldment, respectively, constituting a workpiece clamping system, and are located at the right and left ends of the bottom platform; the right-side fixed clamping system includes: Force sensor mounting base: It is an inverted T-shaped base, with the lower horizontal surface used for fixed connection with the bottom platform and the upper vertical surface fixed connection with the lower mounting plate of the force sensor. Fixed end clamp: The bottom is fixedly connected to the mounting plate on the force sensor and is used to rigidly clamp the right end of the metal welded part; Six-dimensional force sensor: fixed between the upper mounting plate and the lower mounting plate of the force sensor, used to collect force signals of metal welded parts in real time; The left-side active compliant clamping system includes: a lower compliant drive module and an upper workpiece clamping module; the lower compliant drive module includes: Drive base: Fixed to the bottom platform, with two linear guide rails equipped with guide rail sliders installed parallel to each other along the long axis. Fixed end bearing support is installed on the left short axis side, and support end bearing support is installed on the right short axis side. Ball screw: Equipped with a screw nut, one end is connected to the support end bearing support, and the other end is connected to the output shaft of the servo motor to the fixed end bearing support via a coupling; Sliding platform: It is fixedly connected to the lead screw nut via a nut mounting flange, and also fixedly connected to the guide rail slider; Servo motor: used to drive the ball screw to rotate, which is converted into linear motion of the screw nut along the guide direction of the linear guide, thereby driving the sliding platform to perform linear reciprocating motion along the linear guide; The upper workpiece clamping module is fixedly connected to the sliding platform of the lower compliant drive module and is used to rigidly clamp the left end of the metal weldment. The welding fixture is located at the weld seam of the metal weldment and is used to clamp the metal weldment before welding.

[0010] Optionally, the force sensor mounting base has a reinforcing rib structure; Optionally, the six-dimensional force sensor is used to detect welding stress and torque in the X, Y, and Z directions, and is connected to the lower mounting plate and the upper mounting plate of the force sensor by bolts respectively. Optionally, the right-side fixing clamping system has bolt holes at the bottom of the base and at the top of the base on the lower horizontal surface and the upper vertical surface, respectively, which are connected to the bottom platform and the lower mounting plate of the force sensor by bolts. Optionally, the lower mounting plate of the force sensor is provided with base connection bolt holes and force sensor connection bolt holes, and the force sensor mounting base and the six-dimensional force sensor are respectively connected by bolts; Optionally, the mounting plate on the force sensor is provided with a six-dimensional force sensor connection hole and a fixed end clamp connection hole, and the six-dimensional force sensor and the fixed end clamp are respectively connected by bolts.

[0011] Optionally, the fixed end clamp includes a first fixed end clamp base, a first screw, a first clamp slider, and a first clamping block; Optionally, the first fixed end clamp base: the right side is fixedly connected to the mounting plate on the force sensor by bolts, the left side is a groove structure with front and rear through, a first screw rod with front and rear through is fixed in the groove, and two first clamp sliders are fixed on the left side of the groove wall; Optionally, the first clamping slider: a first clamping block is fixedly connected to the left side of each of the two first clamping sliders; Optionally, the first clamping block is designed according to the shape of the metal welded part and is used to clamp the right end of the metal welded part while ensuring that the contact surfaces are tightly fitted. Optionally, the first fixed end clamp base is connected to the upper mounting plate of the force sensor.

[0012] Optionally, the upper workpiece clamping module includes a second fixed end clamping base, a second screw, a second clamping slider, and a second clamping block; Optionally, the second fixed end clamp base: the lower side is fixedly connected to the sliding platform by bolts, the upper side is a groove structure with front and rear through, a second screw with front and rear through is fixed in the groove, and two second clamp sliders are fixed on the upper side of the groove wall; Optionally, the second clamping slider: a second clamping block is fixedly connected to the upper side of each of the two second clamping sliders; Optionally, the second clamping block is designed according to the shape of the metal welded part and is used to clamp the left end of the metal welded part while ensuring that the contact surfaces fit tightly.

[0013] Optionally, the welding fixture includes an upper welding fixture, a lower welding fixture, a fixture tightening bolt, a fixture tightening nut, and a fixture guide sleeve; the inner surface shape of the lower welding fixture is adapted to the rear profile of the metal weldment; the upper welding fixture is arranged opposite to the lower welding fixture, and its inner surface shape is adapted to the front profile of the metal weldment; the fixture guide sleeve is fixedly installed in the lower welding fixture to provide guidance for the fixture tightening bolt; the fixture tightening bolt causes the upper and lower welding fixtures to clamp the metal weldment together; both the upper and lower welding fixtures are integral components with reinforcing ribs on their outer surfaces.

[0014] Optionally, the welding test bench for testing the welding performance of aerospace metal components further includes a human-computer interaction software system; The human-machine interface software system communicates with the PLC controller to operate and monitor the welding stress compliance control process, display welding stress information during the welding process and the post-weld control stage, and display and record displacement compensation information formed during the post-weld compliance control process. It also provides the function of setting welding stress compliance control parameters. The human-computer interaction software system includes at least a data display module, a parameter setting module, and a status monitoring module, wherein: the data display module is used to display real-time changes in welding stress and displacement compensation data formed during the post-weld adjustment stage; the parameter setting module is used to set the target safety force value and welding stress compliance adjustment parameters; and the status monitoring module is used to display the operating status of the welding test bench and the control system, and send the corresponding set parameters and control commands to the PLC controller.

[0015] Optionally, the welding test bench has at least two working modes: a rigid clamping force measurement mode and a compliant clamping control mode. In the rigid clamping force measurement mode, the left active compliant clamping system maintains a locked position, and both ends of the metal weldment are in a rigid clamping state. The six-dimensional force sensor is used to collect welding stress generated during the welding process and the post-weld cooling stage in real time. In the compliant clamping control mode, the left active compliant clamping system allows axial displacement adjustment while maintaining the clamping constraint without abrupt changes, so as to reduce welding shrinkage force and achieve controlled release of welding stress. In the compliant clamping control mode, the axial displacement generated by the left active compliant clamping system forms a cumulative axial displacement during the post-weld control stage.

[0016] The present invention also provides a method for controlling welding stress compliance according to the welding test bench for testing the welding performance of aerospace metal components, comprising: S1. In the rigid clamping force measurement mode, the six-dimensional force sensor integrated into the right-side fixed clamping system collects the dynamic force signal of the metal welded part that changes rapidly due to cooling and contraction in real time, and filters and processes it to obtain the real-time force value. F ( t ),in t Indicates time; S2. In compliant clamping control mode, a target safety force value between the metal weldment and the welding fixture is preset in the control software. F target Simultaneously, the Ziegler-Nichols empirical tuning method was used to determine a set of optimal proportional gains. K p With differential gain K d , which are input to the PLC controller as fixed control parameters; S3, Calculate real-time force value F ( t ) and target safety force value F target The difference is taken as the instantaneous force error between the two. e ( t ), for time t Differentiation yields the rate of change of instantaneous force error within the current control cycle; S4. Based on the proportional-derivative control law, according to the required instantaneous force error... e ( t ) and its rate of change, combined with the optimal proportional gain K p With differential gain K d The control signal is calculated. u ( t), as the required displacement compensation amount u ( t ); S5, Displacement compensation amount u ( t Amplitude limiting is performed to obtain the final displacement compensation amount. u final ( t ), and convert them into pulse commands; S6, PLC controller generates displacement compensation amount u final ( t The pulse control command is sent to the servo driver, which drives the servo motor to rotate the ball screw, which in turn converts the ball screw nut into linear motion along the guide direction of the linear guide, thereby pushing the sliding platform to generate a slight compensation displacement along the linear guide. After the displacement, the six-dimensional force sensor captures the welding stress change of the metal weldment again, as the input for the next control cycle. S7. Repeat steps S2-S6 to form a continuous closed-loop compliant control of welding stress until the welding stress captured by the six-dimensional force sensor stabilizes at the preset target safety force value. F target Within ±5%, or after reaching the preset adjustment time, the welding stress compliance adjustment process is completed; S8. After completing the welding stress compliance adjustment, record the cumulative axial displacement generated by the left active compliance clamping system during the post-weld adjustment stage, and store, display or analyze the cumulative axial displacement as the equivalent deformation caused by welding shrinkage.

[0017] Optionally, in step S1, the dynamic force signal of the metal welded part that changes drastically due to cooling and contraction is collected and filtered to obtain the real-time force value. F ( t ),include: Acquire raw dynamic welding force signals F raw ( t ); For the original dynamic welding force signal F raw ( t The force value is obtained by filtering. F ( t The formula is expressed as follows: ; in, α These are the filter coefficients.

[0018] Optionally, in step S5, the displacement compensation amount u ( tAmplitude limiting is performed to obtain the final displacement compensation amount. u final ( t ),include: Set the minimum and maximum allowable displacement compensation amounts within a single control cycle. u min , u max ; By constraining the displacement compensation amount within this range, the final displacement compensation amount is obtained. u final ( t The formula is expressed as follows: .

[0019] By means of the above technical solution, the present invention provides a welding test bench and a method for welding stress compliance control for testing the welding performance of aerospace metal components, which has at least the following beneficial effects: (1) The welding test bench and welding stress compliance control method proposed in this invention for testing the welding performance of aerospace metal components are aimed at the common needs of welding aerospace metal components. They solve the problems of residual stress concentration, post-weld shrinkage force overflow damage to tooling, easy failure of product positioning accuracy and high dependence on experience in process debugging of existing rigid welding fixtures in the welding of aerospace aluminum alloy components, and improve the quality and performance of welding products of aerospace aluminum alloy components. (2) The left active compliant clamping system of the present invention consists of a lower compliant drive module and an upper workpiece clamping module, which serve as the actuator for compliant control. The right fixed clamping system is rigidly fixed to the bottom platform and integrates a six-dimensional force sensor, which can collect the dynamic welding stress value of the fixed end in real time after the welding starts, in order to support the compliant control of welding stress. (3) By integrating real-time force sensing and active compliance control, this invention constructs a closed-loop system that can accurately sense and intelligently regulate welding stress, realizing a technological leap from "passive rigid constraint" to "active stress release". The closed-loop system maintains rigidity during the welding process to ensure morphological accuracy, and actively and smoothly releases shrinkage stress during the critical cooling period after welding through micro-displacement compensation based on proportional-differential algorithm. This effectively suppresses welding deformation while significantly reducing residual stress concentration, fundamentally improving the fatigue performance and service reliability of welded components, and providing a standardized precision assurance solution for aerospace manufacturing that does not rely on experience. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a main structural view of a welding test bench for testing the welding performance of aerospace metal components constructed according to the present invention. Figure 2 This is a structural view of the right-side fixing and clamping system of the present invention; Figure 3 This is a structural view of the fixed-end clamp of the present invention; Figure 4 This is a structural view of the active compliant clamping system on the left side of the present invention; Figure 5 This is a structural view of the welding fixture of the present invention; Figure 6 This is a schematic diagram of the human-computer interaction software system of the present invention; Figure 7 This is a schematic diagram of the overall welding test bench constructed by the present invention for testing the welding performance of aerospace metal components.

[0021] In the diagram: 1- Bottom platform; 2- Right-side fixing and clamping system; 3- Metal welded parts; 4- Welding fixture; 5- Left-side active compliant clamping system; 6- Force sensor mounting base; 7- Bottom bolt holes of the base; 8- Base reinforcing rib; 9- Upper bolt holes of the base; 10- Lower mounting plate of the force sensor; 11- Force sensor connecting bolt holes; 12- Base connecting bolt holes; 13- Six-dimensional force sensor; 14- Upper mounting plate of the force sensor; 15- Six-dimensional force sensor connecting hole; 16- Fixed end fixture connecting hole; 17- Fixed end fixture; 18- First fixed end fixture base; 19- First screw; 20 21-First clamping block; 22-Drive base; 23-Linear guide rail; 24-Guide rail slider; 25-Support end bearing support; 26-Sliding platform; 27-Second fixed end clamping base; 28-Second screw; 29-Second clamping block; 30-Second clamping block; 31-Fixed end bearing support; 32-Servo motor; 33-Coupling; 34-Ball screw; 35-Screw nut; 36-Nut mounting flange; 37-Upper welding clamp; 38-Clamping bolt; 39-Lower welding clamp; 40-Clamping guide sleeve; 41-Clamping nut. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding of how the present application uses technical means to solve technical problems and achieve technical effects, and to facilitate its implementation.

[0023] The following specific embodiments use aerospace aluminum alloy welded parts as preferred examples to illustrate the welding test bench and welding stress compliance control method for testing the welding performance of aerospace metal components described in this invention. However, this invention is not limited to this material system.

[0024] Those skilled in the art will understand that all or part of the steps in the implementation of the methods of the embodiments can be implemented by a program instructing related hardware. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0025] Please refer to Figures 1-7 This illustration shows a specific implementation of the present embodiment. This embodiment integrates a six-dimensional force sensor for real-time monitoring of welding stress into the right-side fixed clamping system, and sets up a precision displacement mechanism based on a servo motor in the left-side active compliant clamping system. This constitutes a welding test bench for testing the welding performance of aerospace metal components, with two working modes: a rigid clamping mode and a compliant clamping control mode. Simultaneously, based on a preset target safety force value and combined with the principle of a PD controller, a welding stress compliant control method is designed to acquire welding stress in real time, calculate displacement compensation, and cyclically perform welding stress compliant control, thereby achieving control of welding stress during the welding process and post-weld cooling stage. By receiving the controlled release of compressive stress, a closed-loop system is formed that can accurately sense and intelligently regulate welding stress. Through a control and interaction platform composed of a PLC controller and a human-machine interface software system, the welding force state, regulation process, and post-weld equivalent deformation displacement are uniformly displayed and recorded. Thus, while ensuring the macroscopic morphological accuracy of the welded component, the system achieves active regulation of welding stress and quantifiable testing of post-weld deformation. It effectively suppresses welding deformation and significantly reduces residual stress concentration, fundamentally improving the fatigue performance and service reliability of the welded component, and providing a standardized precision assurance solution for aerospace manufacturing that does not rely on experience.

[0026] Please refer to Figure 1 This embodiment proposes a welding test bench for testing the welding performance of aerospace metal components, including: a bottom platform 1, a right-side fixed clamping system 2, a welding fixture 4, and a left-side active compliant clamping system 5.

[0027] The right-side fixed clamping system 2 and the left-side active compliant clamping system 5 are respectively used to clamp the right and left ends of the metal welded parts 3 (including but not limited to aviation aluminum alloy components, titanium alloy components and other commonly used aviation metal components), forming a workpiece clamping system, which is set on the right and left ends of the bottom platform 1. The welding fixture 4 is positioned at the weld seam of the metal weldment 3 and is used to clamp the metal weldment 3 before welding.

[0028] Please refer to Figure 2 The right-side fixed clamping system 2 integrates a six-dimensional force sensor 13, which is used to collect force signals (including welding stress and torque) of the metal welded parts 3 in real time. Specifically, the six-dimensional force sensor 13 is used to detect welding stress and torque in the X, Y and Z directions, and is connected to the lower mounting plate 12 and the upper mounting plate 14 of the force sensor by bolts.

[0029] The right-side fixed clamping system 2 further includes: a force sensor mounting base 6, a lower force sensor mounting plate 10, an upper force sensor mounting plate 14, and a fixed end clamp 17; the force sensor mounting base 6 is an inverted T-shape with a reinforcing rib structure 8, and the lower horizontal surface and upper vertical surface are respectively provided with base bottom bolt holes 7 and base upper bolt holes 9, which are fixedly connected to the bottom platform 1 and the lower force sensor mounting plate 10 by bolts; the lower force sensor mounting plate 10 is provided with base connecting bolt holes 12 and force sensor connecting bolt holes 11, which are fixedly connected to the force sensor mounting base 6 and the six-dimensional force sensor 13 by bolts; the upper force sensor mounting plate 14 is provided with a six-dimensional force sensor connecting hole 15 and a fixed end clamp connecting hole 16, which are connected to the six-dimensional force sensor 13 and the fixed end clamp 17 by bolts; the fixed end clamp 17 is used to rigidly clamp the right end of the metal welded part 3.

[0030] Please refer to Figure 3 Specifically, the fixed end clamp 17 includes a first fixed end clamp base 18, a first screw 19, a first clamp slider 20, and a first clamping block 21.

[0031] The first fixed end clamp base 18: the right side is fixedly connected to the mounting plate 14 of the force sensor by bolts, the left side is a groove structure with front and back passage, the first screw 19 with front and back passage is fixed in the groove, and two first clamp sliders 20 are fixed on the left side of the groove wall. The first clamping slider 20: The left side of each of the two first clamping sliders 20 is fixedly connected to a first clamping block 21; The first clamping block 21 is designed according to the shape of the metal welded part 3 and is used to clamp the right end of the metal welded part 3 while ensuring that the contact surfaces are tightly fitted. The first fixed end clamp base 18 is connected to the upper mounting plate 14 of the force sensor below it.

[0032] The left-side active compliant clamping system 5 and the right-side fixed clamping system 2 are positioned opposite each other. Please refer to [the relevant documentation]. Figure 4 It includes a lower-level compliant drive module and an upper-level workpiece clamping module.

[0033] The lower compliant drive module includes a drive base 22, a servo motor 32, a coupling 33, a fixed-end bearing support 31, a supporting-end bearing support 25, a linear guide rail 23, a guide rail slider 24, a ball screw 34, a screw nut 35, a nut mounting flange 36, and a sliding platform 26. The drive base 22 is fixed to the bottom platform 1. Two linear guide rails 23 equipped with guide rail sliders 24 are installed parallel to each other along the long axis of the drive base 22. The fixed-end bearing support 31 is installed on the left short axis side, and the supporting-end bearing support 25 is installed on the right short axis side. The ball screw 34 is equipped with a screw nut 35. One end is connected to the supporting-end bearing support 25, and the other end is connected to the output shaft of the servo motor 32 via a coupling 33 to the fixed-end bearing support 31. The sliding platform 26 is fixedly connected to the screw nut 35 via the nut mounting flange 36, and also fixedly connected to the guide rail slider 24.

[0034] When the welding test bench is working, the servo motor 32 drives the ball screw 34 to rotate. The axis of the ball screw 34 is parallel to the guiding direction of the linear guide rail 23. Under the constraint of the guide rail slider 24, the linear motion direction of the screw nut 35 is consistent with the motion direction of the sliding platform 26, thereby pushing the sliding platform 26 to perform linear reciprocating motion along the linear guide rail 23. When performing welding stress compliance control, the sliding platform 26 can be slightly compensated for displacement in the above manner.

[0035] In addition to driving the sliding platform 26 to generate precise linear displacement, this lower compliant drive module, together with the upper workpiece clamping module, constitutes a controllable clamping boundary adjustment structure, enabling the metal weldment to gradually transition from a completely rigid constraint to a controlled compliant constraint during the post-weld cooling stage. Through servo-driven micro- and continuous displacement adjustment, the smooth release of welding shrinkage stress is achieved, avoiding the stress release and secondary deformation problems caused by the one-time release of traditional clamps. Furthermore, the welding stress release process is transformed from an experience-dependent operation into a repeatable and quantifiable process.

[0036] The upper workpiece clamping module and the sliding platform 26 of the lower compliant drive module are connected by bolts; the upper workpiece clamping module is identical in form to the fixed end clamp 17 of the right fixed clamping system 2, and is used to rigidly clamp the left end of the metal welded part 3. Specifically, the upper workpiece clamping module includes a second fixed end clamping base 27, a second screw 28, a second clamping slider 29, and a second clamping block 30; The second fixed end clamp base 27: the lower side is fixedly connected to the sliding platform 26 by bolts, the upper side is a groove structure with front and back passage, the groove is fixed with a second screw 28 with front and back passage, and two second clamp sliders 29 are fixed on the upper side of the groove wall; The second clamping slider 29: The upper sides of the two second clamping sliders 29 are respectively fixedly connected with second clamping blocks 30; The second clamping block 30 is designed according to the shape of the metal welded part 3 and is used to clamp the left end of the metal welded part 3 while ensuring that the contact surfaces are tightly fitted.

[0037] Specifically, please refer to Figure 5 The welding fixture 4 includes an upper welding fixture 37, a lower welding fixture 39, a fixture tightening bolt 38, a fixture tightening nut 41, and a fixture guide sleeve 40, all of which are made of 45 steel.

[0038] The inner surface shape of the lower welding fixture 39 is adapted to the rear shape of the metal welded part 3; the upper welding fixture 37 is arranged opposite to the lower welding fixture 39, and its inner surface shape is adapted to the front shape of the metal welded part 3. The clamp guide sleeve 40 is fixedly installed on the lower welding clamp 39 to provide guidance for the clamp tightening bolt 38; the clamp tightening bolt 38 can enable the upper welding clamp 37 and the lower welding clamp 39 to clamp the metal weldment 3 together. Both the upper welding fixture 37 and the lower welding fixture 39 are integral components with reinforcing ribs on their outer surfaces.

[0039] The active compliant clamping system on the left side of this invention consists of a lower compliant drive module and an upper workpiece clamping module, serving as the actuator for compliant control. The fixed clamping system on the right side is rigidly fixed to the bottom platform and integrates a six-dimensional force sensor, which can collect the dynamic welding stress value at the fixed end in real time after welding begins, supporting compliant control of welding stress. The welding fixture is loaded at the weld seam of the weldment before welding to resist post-weld shrinkage and post-weld deformation overflow.

[0040] like Figure 7 As shown, the welding test bench for testing the welding performance of aerospace metal components also includes a human-computer interaction software system.

[0041] The human-machine interface software system communicates with the PLC controller to operate and monitor the welding stress compliance control process, display welding stress information during the welding process and the post-weld control stage, and display and record displacement compensation information formed during the post-weld compliance control process. It also provides the function of setting welding stress compliance control parameters. The human-computer interaction software system includes at least a data display module, a parameter setting module, and a status monitoring module, wherein: the data display module is used to display real-time changes in welding stress and displacement compensation data formed during the post-weld adjustment stage; the parameter setting module is used to set the target safety force value and welding stress compliance adjustment parameters; and the status monitoring module is used to display the operating status of the welding test bench and the control system, and send the corresponding set parameters and control commands to the PLC controller.

[0042] The welding test bench has at least two working modes: rigid clamping force measurement mode and compliant clamping control mode. In the rigid clamping force measurement mode, the left active compliant clamping system 5 maintains a locked position, and both ends of the metal weldment 3 are in a rigid clamping state. The six-dimensional force sensor 13 is used to collect welding stress generated during the welding process and the post-weld cooling stage in real time. In the compliant clamping control mode, the left active compliant clamping system 5 allows axial displacement adjustment while maintaining the clamping constraint without abrupt changes, so as to reduce welding shrinkage force and achieve controlled release of welding stress. In the compliant clamping control mode, the axial displacement generated by the left active compliant clamping system 5 forms a cumulative axial displacement during the post-weld control stage. The cumulative displacement is used to characterize the equivalent deformation caused by welding shrinkage, and the equivalent deformation corresponds to the reduction of the overall effective length of the metal weldment 3.

[0043] This application also provides a welding stress compliance control method for a welding test bench for testing the welding performance of aerospace metal components. The following describes the welding test bench and welding stress compliance control method for testing the welding performance of aerospace metal components according to the present invention, using an aerospace 6061 aluminum alloy welded part as the welding test object.

[0044] The aluminum alloy welded parts are made of 6061 series aluminum alloy sheets commonly used in aerospace structures. The welded parts are butt-welded V-shaped structures, with each sheet approximately 300mm long, 80mm wide, and 2mm thick. The sheet material is locally thickened in the weld area, with a thickened zone of approximately 6mm, and a V-shaped bevel is machined at the butt joint. The weld is positioned in the middle along the length of the sample. Robotic metallic inert gas (MIG) welding is used. During welding and post-weld cooling, these 6061 aluminum alloy butt welded parts exhibit significant axial welding shrinkage and welding stress accumulation, displaying typical post-weld stress and deformation characteristics of aerospace aluminum alloys. This makes them suitable as a specific embodiment of a method for regulating welding stress compliance and quantifying post-weld equivalent deformation.

[0045] The method for controlling welding stress compliance in the welding test bench used for testing the welding performance of aerospace metal components includes the following steps: First, clamp the welded parts and initialize the system: Before welding, the aerospace 6061 aluminum alloy weldment is clamped onto the welding test bench of the present invention. One end of the weldment is rigidly clamped by the right-side fixed clamping system and rigidly connected to the six-dimensional force sensor; the other end is clamped by the left-side active compliant clamping system. The left clamping end is clamped by the upper workpiece clamping module, and the lower compliant drive module consists of a servo motor, a ball screw, and a linear guide rail, which is used to realize the micro-displacement adjustment of the weldment in the axial direction under the action of control commands.

[0046] Welding fixtures are installed at the weld location to locally constrain the thickened area near the weld, thereby limiting the warping deformation of the weld area during welding and ensuring the quality of the weld formation.

[0047] After clamping, the welding test bench is initialized: the current position of the left active compliant clamping system is set as the displacement zero point through the human-machine interaction software system, the six-dimensional force sensor is zeroed and calibrated, and the servo driver, PLC controller and communication status are checked to see if they are normal.

[0048] The interface of the aforementioned human-computer interaction software system can be referred to as follows. Figure 6 It is used to display welding stress data collected by a six-dimensional force sensor in real time, including the curve of welding stress changing over time, the current real-time force value, the target safe force value, and the real-time welding force deviation ((real-time force value - target safe force value) / target safe force value × 100%). At the same time, the human-computer interaction software system provides the setting function of welding stress compliance control parameters, including the setting of target safe force value, proportional gain parameter, differential gain parameter, and displacement compensation limit parameter.

[0049] The human-computer interaction software system is also used to display and record displacement compensation information formed during the post-weld compliance control stage, including the displacement compensation amount in the current control cycle, the total amount of axial welding deformation accumulated during the control process, and the control start time and real-time control time, thereby realizing the visualization monitoring and data retention of the welding stress control process and post-weld deformation results.

[0050] In addition, the interface of the human-computer interaction software system also displays the system operating status, PLC communication status, and whether the servo motion status is normal.

[0051] Next, we will perform oscillating MIG welding under rigid clamping force measurement mode: Before welding begins, the welding test bench is set to rigid clamping force measurement mode. In this mode, the left-side active compliant clamping system remains locked, and high-rigidity clamping boundaries are formed at both ends of the weldment, preventing axial displacement of the weldment during welding.

[0052] The robotic MIG welding program is then initiated, and the welding torch continuously welds the V-groove along the weld centerline. In this embodiment, the welding process employs a single-oscillation welding method. The welding torch advances along the weld centerline while simultaneously oscillating laterally, allowing the molten welding wire to fully fuse with the base material and gradually fill the V-groove, thereby obtaining a continuous weld structure with a full cross-section in a single welding process. As an example, the lateral oscillation amplitude of the welding torch during the oscillation welding process is set to 2-3 mm, the oscillation frequency to 1.5-2.5 Hz, the welding current to the range of 90-130 A, and the welding voltage to the range of 18-22 V. These parameters can be adjusted according to the thickness of the weldment and the welding process requirements.

[0053] As the weld area undergoes heating, melting, and subsequent cooling and solidification during the oscillating welding process, the aerospace 6061 aluminum alloy welded parts exhibit a significant welding shrinkage trend in the axial direction. Since the two ends of the welded parts are in a rigid clamping state during the welding stage, this shrinkage trend is constrained and transformed into welding stress, which gradually accumulates during the welding completion and post-weld cooling stages.

[0054] S1. Perform welding stress acquisition and filtering: During the current control cycle, the six-dimensional force sensor 13, integrated into the right-side fixed clamping system 2, acquires the dynamic force signal of the aerospace 6061 aluminum alloy welded part, which changes rapidly due to cooling and contraction, at a sampling frequency of 100Hz, and performs filtering processing to obtain the real-time force value. F ( t ),in t The time is indicated. The dynamic force signal contains high-frequency transient disturbance components introduced by factors such as welding arc instability, molten pool fluctuations, and rapid changes in temperature gradient. These disturbances do not reflect the true welding shrinkage stress state of the aluminum alloy weldment.

[0055] As a preferred embodiment of step S1, the specific process includes: Acquire raw dynamic welding force signals F raw ( t ); For the original dynamic welding force signal F raw ( t Filtering is performed to eliminate high-frequency noise and prevent it from interfering with the differential term, resulting in a real-time force value that can be used for control. F ( t The mathematical formula is as follows: ; in, α These are the filter coefficients.

[0056] During this process, the PLC controller runs the control cycle at a high frequency of no less than 1kHz, reads the latest available data from the sensor in each control cycle, ensures that the dynamic changes in welding stress can be captured in a timely manner, and controls the total delay to within 1ms, thereby ensuring the speed and stability of the closed-loop control.

[0057] Through the above filtering process, not only can the amplification effect of high-frequency noise on the differential control term during welding be suppressed, but the overall evolution trend of welding shrinkage stress during the post-weld cooling stage can also be effectively extracted, avoiding excessive response of the control system to instantaneous disturbances. This prevents the actuator from frequently reversing during subsequent stress compliance control, ensuring the continuity and smoothness of the clamping boundary adjustment process.

[0058] During the experiment, it was observed that the welding stress rose rapidly during the cooling phase after welding, then changed slowly, eventually maintaining a high level with a peak force of approximately 1800-2000 N. The welding stress data during this phase was transmitted in real-time to the PLC controller and simultaneously displayed on the interface of the human-machine interface software system, such as... Figure 6 As shown, this provides a basis for setting parameters for subsequent compliance control modes.

[0059] S2. Switching between compliant clamping control modes and setting parameters: Specifically, after the robot's MIG welding program is completed, the welding test bench switches from a rigid clamping force measurement mode to a compliant clamping control mode. During the switching process, the right-side fixed clamping system remains locked, while the left-side active compliant clamping system maintains continuous clamping of the weldment, only switching from a position-locked state to a compliant state that allows controlled axial displacement. The entire switching process does not cause a sudden change in clamping stiffness, thereby avoiding the instantaneous release of welding stress.

[0060] After entering the compliant clamping control mode, the welding stress compliance control parameters are set through the human-machine interface software system. A target safety force value between the aluminum alloy weldment 3 and the welding fixture 4 is preset through the human-machine interface system. F target Meanwhile, considering the characteristics of aluminum alloy weldments during welding, especially in the post-weld cooling stage, such as rapid changes in internal stress, significant temperature variations in system dynamics, and difficulty in establishing accurate mathematical models, the Ziegler-Nichols empirical tuning method was used to determine an optimal set of proportional gains. K p With differential gain K d It is used as a fixed control parameter input to the PLC controller.

[0061] The Ziegler-Nichols empirical tuning method, specifically, first involves adjusting the differential gain... Kd Setting it to 0 temporarily puts the PD controller into pure proportional P mode, from a smaller proportional gain. K p Initially, operate the system in stress-controlled mode. Gradually increase... K p The numerical value was determined, and the force response of the stress modulation process to small perturbations was observed. When a sustained, constant-amplitude critical oscillation occurred, the critical proportional gain at this point was recorded. K u And measure the critical period of the oscillation. T u The operator or process engineer sets the PLC controller parameters according to the empirical formula of the PD controller to determine an optimal set of proportional gain. K p With differential gain K d The calculation method is as follows: ; In this embodiment, the target safety force value F target Set to 1200N, proportional gain K p The differential gain is set to 0.002 mm / N. K d The control time is set to 0.0005 mm / (N·s), and the control cycle is set to 1 ms. Simultaneously, the displacement compensation within a single control cycle is limited, with the maximum displacement compensation set to ±0.02 mm. These parameters are determined comprehensively based on the geometric dimensions, welding process conditions, and post-weld shrinkage characteristics of the aerospace 6061 aluminum alloy welded parts. This ensures that the compliant control process guarantees a smooth release of welding stress while avoiding secondary vibrations or local instability caused by excessively rapid displacement adjustment.

[0062] S3. Perform welding stress compliance control and displacement compensation: In compliant clamping control mode, the PLC controller continuously runs the welding stress compliance control algorithm according to a preset control cycle. Within each control cycle, the PLC controller reads the real-time force value. F ( t ), calculate real-time force value F ( t ) and target safety force value F target The difference is taken as the instantaneous force error between the two. e ( t ), for time t The rate of change of instantaneous force error within the current control cycle is obtained by taking the derivative.

[0063] Specifically, instantaneous force errore ( t The calculation method is as follows: ; e ( t A value greater than 0 indicates that the force applied is too great and needs to be released. e ( t A value less than 0 indicates that the force is too small, and the clamping force can be adjusted appropriately.

[0064] The rate of change of instantaneous force error is calculated as follows: ; in, ∆t To control the cycle: express e ( t )right t The derivative is the rate of change, which is used to characterize the dynamic trend of welding stress.

[0065] S4. Based on the proportional-derivative (PD) control law, the welding stress generated during the welding process and post-weld cooling stage is taken as the control object, and the instantaneous force error is calculated accordingly. e ( t ) and its rate of change, combined with the optimal proportional gain K p With differential gain K d The control signal is calculated. u ( t ), as the required displacement compensation amount u ( t This allows for direct control of the welding stress state.

[0066] Unlike existing control methods that directly apply control output to processing equipment or motion trajectory, this invention transforms the control quantity calculated by the PD control law into a micro-displacement compensation at the clamping end, which is used to actively adjust the clamping boundary conditions of the workpiece, so that the welding shrinkage stress is gradually released under controlled conditions, rather than being forcibly suppressed by rigid constraints.

[0067] Specifically, the control signal is calculated based on the proportional-derivative (PD) control law. u ( t The formula for ) is: ; The proportional term is used to adjust the degree to which the welding stress deviates from the target safe force value, while the differential term is used to reflect the trend of welding stress change.

[0068] The faster the welding stress increases, the more the differential term... This will generate a correspondingly larger reverse displacement to suppress the tendency of the stress to rise, reduce overshoot and system oscillation, and improve the smoothness and stability of the compliant control process.

[0069] S5. To prevent excessive movement of the actuator, the displacement compensation amount... u ( t Amplitude limiting is performed to obtain the final displacement compensation amount. u final ( t ), and convert them into pulse commands.

[0070] As a preferred embodiment of step S5, the displacement compensation amount u ( t Amplitude limiting is performed to obtain the final displacement compensation amount. u final ( t The specific process includes: Set the minimum and maximum allowable displacement compensation amounts within a single control cycle. u min , u max ; By constraining the displacement compensation amount within this range, the final displacement compensation amount is obtained. u final ( t The mathematical formula is as follows: .

[0071] S6, PLC controller generates displacement compensation amount u final ( t The pulse control command is sent to the servo driver, which drives the left-side active compliant clamping system 5 to generate a slight compensation displacement. Specifically, the servo driver drives the servo motor 32 to rotate the ball screw 34, which in turn translates into linear motion of the screw nut 35 along the guide direction of the linear guide rail 23, thereby pushing the sliding platform 26 along the linear guide rail 23. This displacement actively changes the clamping boundary conditions of the aerospace 6061 aluminum alloy welded part, thereby effectively releasing the accumulated welding stress inside it. After the displacement, the six-dimensional force sensor 13 captures the change in welding stress of the aerospace 6061 aluminum alloy welded part again, as the input for the next control cycle.

[0072] By employing the displacement limiting process, excessive displacement of the actuator due to abnormal force signals or transient disturbances can be prevented, thus ensuring the structural safety of the welding test bench. Unlike existing control methods that directly apply control output to the processing equipment or motion trajectory, this invention transforms the control quantity calculated by the proportional-derivative control law into a minute displacement compensation at the clamping end. This is used to actively adjust the workpiece's clamping boundary conditions, allowing welding shrinkage stress to be gradually released under controlled conditions, rather than being forcibly suppressed by rigid constraints. Compared to directly applying control commands to the welding equipment, stress release through adjusting clamping boundary conditions enables stress control without changing welding process parameters, making it more suitable for welding performance testing scenarios.

[0073] By using the aforementioned micro-displacement compensation method, the constraint state of the workpiece clamping end is changed from a completely rigid constraint to a controlled compliant constraint. This allows for the active release of shrinkage stress accumulated during the welding process and the post-weld cooling stage without compromising the macroscopic morphological accuracy of the welded component. This avoids the problems of stress release, secondary deformation, or local instability of the weld caused by traditional clamps during one-time clamping.

[0074] S7. Repeat steps S2-S6 to form a continuous closed-loop compliant control of welding stress.

[0075] As the control process progresses, the equivalent clamping lengths at both ends of the 6061 aluminum alloy welded part gradually shorten, resulting in a continuous and smooth release of welding shrinkage stress. In this embodiment, the compliance control process lasts approximately 200-250 seconds, during which the welding stress gradually decreases from approximately 1800-2000 N initially after welding, and stabilizes within the 1150-1250 N range at the end of the control process, reaching the preset target safety force value. F targee Within ±5%, it indicates that the welding stress has been effectively suppressed and stabilized within a safe range.

[0076] During the compliant clamping control process, the axial displacement generated by the left-side active compliant clamping system during the post-weld cooling and control phase accumulates continuously over multiple control cycles. After control is completed, the system automatically reads and records the cumulative axial displacement formed during this phase. In this embodiment, the measured cumulative displacement is 0.82 mm. This displacement is not the free springback displacement after the welded part is completely released from clamping, but rather the equivalent shrinkage displacement allowed to be released when the welding stress is controlled from a high-stress state to within the target safe force range. Therefore, this cumulative displacement is defined as the equivalent deformation caused by welding shrinkage, and its physical meaning corresponds to the reduction in the overall effective length of the aerospace 6061 aluminum alloy welded part during the post-weld cooling phase. By recording and analyzing this equivalent deformation, a quantitative comparison of welding stress and post-weld deformation characteristics under different welding process conditions can be achieved, providing a basis for welding performance testing and process parameter optimization.

[0077] After achieving the aforementioned compliant clamping adjustment and stabilizing the welding force within the target safe range, post-weld aging treatment can be implemented on the welded parts in this embodiment to further reduce post-weld residual stress and improve the stress state of the welded joint. Specifically, while maintaining the clamping state of the welded parts without drastic changes, a ceramic electric heating blanket is laid on the outer surface of the weld area of ​​the welded parts, and the welded parts are subjected to controlled heating and slow cooling treatment using a temperature control device. In this embodiment, the heating temperature for aging treatment is set to 160–180℃, and the heating rate is controlled to be no more than 20℃ / h; after the welded parts reach the set aging temperature, the holding time is set to 2–4h to promote further relaxation of residual stress in the weld and its adjacent areas; then heating is stopped and natural slow cooling is performed, with the cooling rate controlled to be no more than 15℃ / h, thereby avoiding the introduction of new thermal stress due to excessive temperature gradient. Through the above-mentioned post-weld aging treatment process, the level of post-weld residual stress can be further reduced without damaging the macroscopic morphology and clamping stability of the welded parts, thereby improving the overall stability and service reliability of the welded structure.

[0078] S8. After completing the welding stress compliance adjustment, record the cumulative axial displacement generated by the left active compliance clamping system (5) during the post-weld adjustment stage, and store, display or analyze the cumulative axial displacement as the equivalent deformation caused by welding shrinkage.

[0079] After completing the welding stress compliance control and post-weld aging treatment to slowly lower the overall temperature of the weldment to room temperature, all active control and heating processes were stopped. Subsequently, ensuring the weldment was in a stable state, the welding fixture, the left active compliance clamping system, and the right fixed clamping system were sequentially released, and the aerospace 6061 aluminum alloy weldment was removed from the welding test table. After the test, the appearance and geometric condition of the aerospace 6061 aluminum alloy weldment were inspected, and no obvious warping, sudden springback, or secondary deformation was found, indicating that the welding stress release process was stable and controllable.

[0080] As can be seen from the above implementation process, the present invention maintains rigid clamping during the welding stage to ensure the weld formation quality and macroscopic dimensional accuracy. In the post-weld stage, through the synergistic effect of compliant clamping control and aging treatment, the welding stress is gradually released and the residual stress after welding is further reduced. At the same time, by recording the cumulative axial displacement formed during the post-weld control stage, the welding shrinkage deformation can be quantitatively characterized.

[0081] The welding stress compliance control method of this invention involves a force sensor monitoring the changes in post-weld shrinkage force of the workpiece in real time during the welding process and feeding this data back to the control system. The control system compares and calculates the force data with a preset threshold, generates control commands, and precisely drives the servo motor on the left side. This causes the workpiece clamping end on the left side (upper workpiece clamping module) to generate a corresponding micro-compensation displacement along the linear guide rail. This displacement actively releases the accumulated stress inside the workpiece, thereby achieving closed-loop compliance control based on real-time force feedback.

[0082] This invention integrates real-time force sensing and active compliance control to construct a closed-loop system capable of accurately sensing and intelligently regulating welding stress, achieving a technological leap from "passive rigid constraint" to "active stress release." This closed-loop system maintains rigidity during welding to ensure morphological accuracy, and actively and smoothly releases shrinkage stress during the critical cooling period after welding through micro-displacement compensation based on a proportional-differential algorithm. This effectively suppresses welding deformation while significantly reducing residual stress concentration, fundamentally improving the fatigue performance and service reliability of welded components, and providing a standardized precision assurance solution for aerospace manufacturing that does not rely on experience.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0084] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0085] The above embodiments provide a detailed description of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A welding test bench for testing the welding performance of aerospace metal components, characterized in that, include: The right-side fixed clamping system (2) and the left-side active compliant clamping system (5) are used to clamp the right and left ends of the metal welded parts (3), respectively, forming a workpiece clamping system, which is set on the right and left ends of the bottom platform (1); the right-side fixed clamping system (2) includes: Force sensor mounting base (6): It is an inverted T-shaped base. The lower horizontal surface is used to fix it to the bottom platform (1), and the upper vertical surface is fixedly connected to the lower mounting plate (10) of the force sensor. Fixed end clamp (17): The bottom is fixedly connected to the mounting plate (14) on the force sensor, and is used to rigidly clamp the right end of the metal welded part (3); Six-dimensional force sensor (13): fixed between the upper mounting plate (14) and the lower mounting plate (10) of the force sensor, used to collect force signals of metal welded parts in real time; The left-side active compliant clamping system (5) includes: a lower compliant drive module and an upper workpiece clamping module; the lower compliant drive module includes: Drive base (22): Fixed to the bottom platform (1), with two linear guide rails (23) equipped with guide rail sliders (24) installed parallel to each other along the long axis. Fixed end bearing support (31) is installed on the left short axis side, and support end bearing support (25) is installed on the right short axis side. Ball screw (34): It is equipped with a screw nut (35), one end of which is connected to the support end bearing support (25), and the other end is connected to the output shaft of the servo motor (32) via a coupling (33) on the fixed end bearing support (31); Sliding platform (26): It is fixedly connected to the lead screw nut (35) by the nut mounting flange (36) and at the same time fixedly connected to the guide rail slider (24); Servo motor (32): used to drive the ball screw (34) to rotate, which is converted into linear motion of the screw nut (35) along the guide direction of the linear guide (23), thereby pushing the sliding platform (26) to perform linear reciprocating motion along the linear guide (23); The upper workpiece clamping module is fixedly connected to the sliding platform (26) of the lower compliant drive module and is used to rigidly clamp the left end of the metal welded part (3). The welding fixture (4) is set at the weld position of the metal weldment (3) and is used to clamp the metal weldment (3) before welding.

2. The welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: The force sensor mounting base (6) has a reinforcing rib structure (8); The six-dimensional force sensor (13) is used to detect welding stress and torque in the X, Y and Z directions. It is connected to the lower mounting plate (12) and the upper mounting plate (14) of the force sensor by bolts. The right-side fixing clamping system (2) has a base bottom bolt hole (7) and a base upper bolt hole (9) respectively on its lower horizontal surface and upper vertical surface, which are connected to the bottom platform (1) and the force sensor lower mounting plate (10) respectively by bolts; The lower mounting plate (10) of the force sensor is provided with a base connection bolt hole (12) and a force sensor connection bolt hole (11), and the force sensor mounting base (6) and the six-dimensional force sensor (13) are respectively connected by bolts. The mounting plate (14) of the force sensor is provided with a six-dimensional force sensor connection hole (15) and a fixed end clamp connection hole (16), and the six-dimensional force sensor (13) and the fixed end clamp (17) are respectively connected by bolts.

3. The welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: The fixed end clamp (17) includes a first fixed end clamp base (18), a first screw (19), a first clamp slider (20), and a first clamping block (21). The first fixed end clamp base (18): the right side is fixedly connected to the mounting plate (14) on the force sensor by bolts, the left side is a groove structure with front and back passage, the groove is fixed with a first screw rod (19) with front and back passage, and two first clamp sliders (20) are fixed on the left side of the groove wall. The first clamping slider (20): The left side of each of the two first clamping sliders (20) is fixedly connected to a first clamping block (21); The first clamping block (21): designed according to the shape of the metal welded part (3), is used to clamp the right end of the metal welded part (3) and at the same time ensure that the contact surfaces are tightly fitted; The first fixed end clamp base (18) is connected to the upper mounting plate (14) of the force sensor below it.

4. The welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: The upper workpiece clamping module includes a second fixed end clamp base (27), a second screw (28), a second clamp slider (29), and a second clamping block (30). The second fixed end clamp base (27): the lower side is fixedly connected to the sliding platform (26) by bolts, the upper side is a groove structure with front and back passage, the groove is fixed with a second screw (28) with front and back passage, and two second clamp sliders (29) are fixed on the upper side of the groove wall. The second clamping slider (29): The upper sides of the two second clamping sliders (29) are respectively fixedly connected with second clamping blocks (30); The second clamping block (30) is designed according to the shape of the metal welded part (3) and is used to clamp the left end of the metal welded part (3) while ensuring that the contact surfaces are tightly fitted.

5. A welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: The welding fixture (4) includes an upper welding fixture (37), a lower welding fixture (39), a fixture tightening bolt (38), a fixture tightening nut (41), and a fixture guide sleeve (40). The inner surface shape of the lower welding fixture (39) is adapted to the rear side shape of the metal welded part (3); the upper welding fixture (37) is arranged opposite to the lower welding fixture (39), and its inner surface shape is adapted to the front side shape of the metal welded part (3). The clamp guide sleeve (40) is fixedly installed on the lower welding clamp (39) to provide guidance for the clamp tightening bolt (38); the clamp tightening bolt (38) causes the upper welding clamp (37) and the lower welding clamp (39) to clamp the metal weldment (3) together. Both the upper welding fixture (37) and the lower welding fixture (39) are integral components with reinforcing ribs on their outer surfaces.

6. A welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: This also includes human-computer interaction software systems; The human-machine interface software system communicates with the PLC controller to operate and monitor the welding stress compliance control process, display welding stress information during the welding process and the post-weld control stage, and display and record displacement compensation information formed during the post-weld compliance control process. It also provides the function of setting welding stress compliance control parameters. The human-computer interaction software system includes at least a data display module, a parameter setting module, and a status monitoring module, wherein: the data display module is used to display real-time changes in welding stress and displacement compensation data formed during the post-weld adjustment stage; the parameter setting module is used to set the target safety force value and welding stress compliance adjustment parameters; and the status monitoring module is used to display the operating status of the welding test bench and the control system, and send the corresponding set parameters and control commands to the PLC controller.

7. A welding test bench for testing the welding performance of aerospace metal components according to claim 1, characterized in that: The welding test bench has at least two working modes: rigid clamping force measurement mode and compliant clamping control mode. In the rigid clamping force measurement mode, the left active compliant clamping system (5) maintains a locked position, and both ends of the metal weldment (3) are in a rigid clamping state. The six-dimensional force sensor (13) is used to collect the welding stress generated during the welding process and the cooling stage after welding in real time. In the compliant clamping control mode, the left active compliant clamping system (5) allows axial displacement adjustment under the condition of maintaining the clamping constraint without sudden change, so as to reduce the welding shrinkage force and realize the controlled release of welding stress. In the compliant clamping control mode, the axial displacement generated by the left active compliant clamping system (5) forms a cumulative axial displacement during the post-weld control stage.

8. The method for controlling welding stress compliance in a welding test bench for testing the welding performance of aerospace metal components according to any one of claims 1-7, characterized in that, include: S1. In the rigid clamping force measurement mode, the six-dimensional force sensor (13) integrated into the right-side fixed clamping system (2) collects the dynamic force signal of the metal welded part (3) that changes rapidly due to cooling and contraction in real time and filters it to obtain the real-time force value. F ( t ),in t Indicates time; S2. In the compliant clamping control mode, a target safety force value between the metal weldment (3) and the welding fixture (4) is preset in the control software. F target Simultaneously, the Ziegler-Nichols empirical tuning method was used to determine a set of optimal proportional gains. K p With differential gain K d , which are input to the PLC controller as fixed control parameters; S3, Calculate real-time force value F ( t ) and target safety force value F target The difference is taken as the instantaneous force error between the two. e ( t ), for time t Differentiation yields the rate of change of instantaneous force error within the current control cycle; S4. Based on the proportional-derivative control law, according to the required instantaneous force error... e ( t ) and its rate of change, combined with the optimal proportional gain K p With differential gain K d The control signal is calculated. u ( t ), as the required displacement compensation amount u ( t ); S5, Displacement compensation amount u ( t Amplitude limiting is performed to obtain the final displacement compensation amount. u final ( t ), and convert them into pulse commands; S6, PLC controller generates displacement compensation amount u final ( t The pulse control command is sent to the servo driver, which drives the servo motor (32) to drive the ball screw (34) to rotate, which is then converted into linear motion of the screw nut (35) along the guide direction of the linear guide (23), thereby pushing the sliding platform (26) to generate a small compensation displacement along the linear guide (23); after the displacement, the six-dimensional force sensor (13) captures the welding stress change of the metal weldment (3) again, as the input for the next control cycle; S7. Repeat steps S2-S6 to form a continuous closed-loop compliant control of welding stress until the welding stress captured by the six-dimensional force sensor (13) stabilizes at the preset target safety force value. F targe Within ±5%, the welding stress compliance control process is completed; S8. After completing the welding stress compliance adjustment, record the cumulative axial displacement generated by the left active compliance clamping system (5) during the post-weld adjustment stage, and store, display or analyze the cumulative axial displacement as the equivalent deformation caused by welding shrinkage.

9. The welding stress compliance control method according to claim 8, characterized in that: In step S1, the dynamic force signal of the metal welded part (3) that changes drastically due to cooling and contraction is collected and filtered to obtain the real-time force value. F ( t ),include: Acquire raw dynamic welding force signals F raw ( t ); For the original dynamic welding force signal F raw ( t The force value is obtained by filtering. F ( t The formula is expressed as follows: ； in, α These are the filter coefficients.

10. The welding stress compliance control method according to claim 8, characterized in that: In step S5, the displacement compensation amount u ( t Amplitude limiting is performed to obtain the final displacement compensation amount. u final ( t ),include: Set the minimum and maximum allowable displacement compensation amounts within a single control cycle. u min , u max ; By constraining the displacement compensation amount within this range, the final displacement compensation amount is obtained. u final ( t The formula is expressed as follows: 。

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