Symmetric balanced modular parallel welding system and method with common rail scheduling

Abstract

The present application relates to a kind of symmetrical balanced modular parallel welding systems and methods of common rail scheduling, involve robot welding field.The technical scheme of the present application can reduce the overall welding deformation of workpiece by more than 70% by symmetrical force heat cancellation design, while effectively reducing residual stress, ensuring welding accuracy and workpiece structure stability, fundamentally solving the welding deformation problem of long size thin-walled parts.And, using multi-modular parallel operation mode, long weld welding time is greatly shortened, for multiple weld joint workpiece, near-synchronous welding can be realized, production efficiency is significantly improved, and production cost is reduced;Relying on modular and software-defined working mode, it can quickly adapt to multi-variety, variable-batch production demand, reduce special tooling investment, shorten production changeover time, and improve production flexibility.In addition, by integrating multi-sensor closed-loop feedback mechanism, real-time sensing of welding process dynamic changes can be realized, intelligent real-time matching of process parameters is realized, and process window is effectively widened.

Description

Technical Field

[0001] This invention relates to the field of robotic welding technology, and in particular to a symmetrical balanced modular parallel welding system and method with common track scheduling. Background Technology

[0002] In the field of automated welding of long, thin-walled parts (such as metal bipolar plates for hydrogen fuel cells), controlling welding thermal stress and deformation is a pressing technical challenge. This invention addresses the existing technological background, primarily focusing on conventional solutions adopted by the industry to address this challenge and their inherent limitations. Currently, common technical solutions for controlling welding deformation in long welds include process parameter optimization, rigid fixture restraint, and pre-deformation or post-correction methods. In a few applications requiring high welding precision, attempts have been made to use two fixed-station welding robots to simultaneously weld the same weld from both sides of the workpiece, aiming to achieve partial heat input balance.

[0003] Each of the aforementioned existing technologies has distinct advantages and disadvantages in practical applications: the process parameter optimization method is simple to implement and has a low cost, but for parts with high thermal conductivity or thin walls, the space for reducing heat input is limited, and it often comes at the cost of sacrificing weld penetration and connection strength; the rigid fixture restraint method can effectively control instantaneous deformation during the welding process and ensure the dimensional accuracy of the parts, but its fixture design is complex and costly, and the restraint force will generate residual stress inside the workpiece. After the fixture is released, it is easy to cause new deformation or affect the fatigue life of the workpiece. At the same time, the fixtures are mostly dedicated to specific parts and have poor flexibility; the pre-deformation or post-correction method can ultimately ensure the shape accuracy of the parts, but it requires a precise process database and adds extra processing steps, which is not only inefficient but may also damage the material properties.

[0004] Furthermore, while existing dual-machine symmetrical welding attempts can theoretically offset some thermal stress and mechanical force, they have fundamental flaws: welding robots are mostly stationary or use independent guide rails, and their collaborative accuracy depends on the high-precision absolute positioning and clock synchronization of the two independent devices, resulting in complex system structure, difficult calibration, and high cost; more importantly, the architecture lacks flexibility, cannot dynamically adapt to workpieces of different lengths and weld seam layouts, and is difficult to expand and coordinate the scheduling of more than two welding units.

[0005] In summary, existing technologies may not be able to fundamentally solve the welding deformation problem of long, thin-walled parts, or although they may have some effect, they generally suffer from drawbacks such as high cost, poor flexibility, system complexity, or easy introduction of new defects. Summary of the Invention

[0006] The purpose of this invention is to provide a symmetrical balanced modular parallel welding system and method with common track scheduling to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a symmetrical balanced modular parallel welding system with common-track scheduling, comprising:

[0009] A gantry-type machine tool protective frame is provided with an X-axis linear guide rail, which can move parallel up and down along the columns of the gantry-type machine tool protective frame. At least two pairs of identical modular welding units are provided on the X-axis linear guide rail, each modular welding unit being located on both sides of the X-axis linear guide rail and capable of independent movement along the X-axis linear guide rail. Each modular welding unit includes a slide, a three-axis fine-tuning platform, a welding torch, and a six-dimensional force sensor. The slide is slidably connected to the X-axis linear guide rail, the welding torch is mounted on the slide, and the torch head is mounted on the torch body via the three-axis fine-tuning platform for adjusting the torch head's posture. The six-dimensional force sensor is mounted on the top of the welding torch for real-time acquisition of the contact pressure and torque data applied by the welding torch during the welding process.

[0010] A collaborative scheduling controller, which is communicatively connected to all modular welding units, is configured to control the paired modular welding units to operate in a mirror mode. In the mirror mode, the collaborative scheduling controller drives two symmetrically arranged modular welding units to move synchronously towards or away from each other at symmetrical positions on the workpiece to be welded. It synchronously controls the welding parameters and applied contact forces of the two modular welding units, so that the heat input and mechanical force on the workpiece to be welded are equal in magnitude and opposite in direction, thereby achieving dynamic force-thermal balance in the welding process.

[0011] In some embodiments, Z-axis linear guides are provided on both sides of the gantry machine tool protective frame, and the two ends of the X-axis linear guides are slidably engaged with the Z-axis linear guides of the two sides of the gantry machine tool protective frame to realize the parallel displacement adjustment of the X-axis linear guides in the vertical direction to adapt to workpieces of different thicknesses to be welded; the workpiece to be welded is placed on the Y-axis linear guide, which is located at the bottom inner side of the gantry machine tool protective frame.

[0012] In some embodiments, the X-axis linear guide rail is specifically deployed with two pairs of four identical modular welding units. The four modular welding units are evenly distributed on the left and right sides of the X-axis linear guide rail. The two modular welding units on each side can move independently along the X-axis linear guide rail and form a mirror pair with the corresponding modular welding unit on the opposite side.

[0013] In some embodiments, the three-axis fine-tuning platform is an XYZ three-axis servo fine-tuning platform, used to realize the displacement adjustment and angle attitude adjustment of the welding torch head in three orthogonal directions;

[0014] The signal output terminal of the six-dimensional force sensor is communicatively connected to the collaborative scheduling controller, and is used to feed back the real-time collected contact pressure and torque data to the collaborative scheduling controller.

[0015] In some implementations, the cooperative scheduling controller is configured to execute multi-level mirror cooperative control logic, which includes a global cooperative layer, a motion synchronization layer, a force-thermal coupling control layer, an adaptive adjustment layer, and a safety monitoring and fault tolerance layer that interact sequentially.

[0016] The global collaboration layer is used to receive the CAD model of the workpiece to be welded and the welding process library data, complete the welding task planning and the generation of symmetrical welding paths, and send welding paths and synchronization control commands to the motion synchronization layer.

[0017] The motion synchronization layer is used to complete spatial mirror coordinate mapping and multi-axis motion time synchronization control according to the received symmetrical welding path. Based on the EtherCAT distributed clock synchronization mechanism and electronic gear synchronization strategy, it drives the paired modular welding units to achieve mirror symmetry of spatial position and microsecond-level synchronization of motion.

[0018] The force-thermal coupling control layer is configured to execute dual closed-loop control logic. The inner loop is a contact force closed-loop control, which uses a PID control algorithm with speed feedforward compensation. Based on the real-time feedback data of the six-dimensional force sensor, the contact force of the modular welding unit is adjusted so that the contact forces of the two paired modular welding units are equal in magnitude and opposite in direction. The outer loop is a heat input closed-loop control, which uses an incremental PID control algorithm to synchronously adjust the welding process parameters of the two paired modular welding units so that the heat input of the two units to be welded is consistent. At the same time, the coupling interference between force control and heat control is eliminated through a feedforward decoupling strategy.

[0019] The adaptive adjustment layer is used to dynamically adjust the control parameters of the paired modular welding units based on real-time sensing data during the welding process. The control parameters include contact force, welding process parameters, and movement speed to suppress disturbances during the welding process. The local stiffness of the workpiece to be welded is detected online using a least squares stiffness identification model. When a difference in the local stiffness of the workpiece to be welded is detected, the force or heat input ratio of the symmetrical modular welding units is automatically adjusted according to the stiffness matching strategy to maintain the dynamic force and heat balance of the welding process.

[0020] The safety monitoring and fault tolerance layer is used to monitor the operating status, welding parameters and sensor data of each modular welding unit in the system in real time. When abnormal data or equipment failure is detected, the abnormal alarm process and the preset fault tolerance process are executed to ensure the safe operation of the system.

[0021] In some implementations, the collaborative scheduling controller is a distributed motion control system based on EtherCAT real-time industrial Ethernet, including an industrial PC as the master station and a motion control core. The industrial PC is connected to the servo driver slave station of each modular welding unit via a single EtherCAT bus. The servo motor and six-dimensional force sensor of the three-axis fine-tuning platform of each modular welding unit are connected to the local servo driver of the corresponding modular welding unit to realize the synchronous periodic command issuance and real-time feedback data acquisition of multiple modular welding units.

[0022] In some embodiments, the motion control core includes:

[0023] The core control unit, which uses a high-performance motion control chip or motion control board, is used to carry the motion control algorithm, and is responsible for parsing the synchronous control commands issued by the industrial PC and generating control signals.

[0024] The real-time communication interface module is adapted to the EtherCAT real-time industrial Ethernet and is responsible for receiving the overall command of the industrial PC, simultaneously sending control signals to each servo driver, and receiving sensor data and motor operating status data fed back by the servo drivers.

[0025] The data processing module is used to quickly process real-time data fed back from each modular welding unit, including contact pressure and torque data collected by the six-dimensional force sensor, as well as the operating parameters of the servo motor of the three-axis fine-tuning platform. After filtering and analyzing the data, it feeds it back to the industrial PC, providing data support for the industrial PC to adjust the control strategy and maintain force and heat balance. At the same time, it works with the core control unit to complete the real-time adjustment of closed-loop control.

[0026] In some embodiments, the collaborative scheduling controller is further configured to, during the welding process, control the three-axis fine-tuning platform of each modular welding unit to adaptively adjust the posture of the welding torch head according to the real-time direction of the weld seam, so that the welding torch head angles of the paired modular welding units remain consistent.

[0027] Secondly, the present invention provides a symmetric balanced modular parallel welding method with common track scheduling, the method being applied to the aforementioned symmetric balanced modular parallel welding system with common track scheduling, the method comprising:

[0028] S1. The collaborative scheduling controller loads the CAD model and welding process library of the workpiece to be welded, and generates a symmetrical welding path and welding process parameters.

[0029] S2. The collaborative scheduling controller starts the mirror welding mode and controls the two paired modular welding units to move to the symmetrical starting position of the weld seam of the workpiece to be welded.

[0030] S3. The collaborative scheduling controller drives the paired modular welding units to move synchronously towards or away from each other along the symmetrical welding path, and synchronously controls the welding parameters and applied contact force of the two modular welding units, so that the heat input and mechanical force of the two units to be welded are equal in magnitude and opposite in direction.

[0031] S4. During the welding process, the contact pressure and torque data of each modular welding unit are collected in real time by a six-dimensional force sensor, and the dynamic force and heat balance of the paired modular welding units is maintained through closed-loop regulation.

[0032] In some embodiments, the method further includes:

[0033] S5. During the welding process, the weld direction and local stiffness changes of the workpiece to be welded are detected in real time, and the welding torch head posture, contact force and heat input parameters of the paired modular welding unit are adaptively adjusted to maintain the symmetrical balance of the welding process.

[0034] The beneficial effects of the technical solution provided by this invention include at least the following:

[0035] This technical solution, through a source-based symmetrical force-heat offsetting design, can reduce the overall welding deformation of the workpiece by more than 70%, while effectively reducing residual stress, ensuring welding accuracy and workpiece structural stability, and fundamentally solving the welding deformation problem of long, thin-walled parts. Furthermore, the adoption of a multi-modal parallel operation mode significantly shortens the welding time for long welds, enabling near-synchronous welding of multi-weld workpieces, significantly improving production efficiency and reducing production costs. Relying on modular and software-defined operating modes, it can quickly adapt to the needs of multi-variety, variable-batch production, reducing investment in specialized tooling, shortening production changeover time, and improving production flexibility. In addition, by integrating a multi-sensor closed-loop feedback mechanism, it can perceive dynamic changes in the welding process in real time, achieving intelligent real-time matching of process parameters and effectively broadening the process window. Attached Figure Description

[0036] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0037] Figure 1 The diagram shows a structural schematic of a symmetric balanced modular parallel welding system with common track scheduling, provided by an exemplary embodiment of the present invention.

[0038] Figure 2 The diagram shows a structural schematic of a modular welding unit in a symmetric balanced modular parallel welding system with common-track scheduling, provided by an exemplary embodiment of the present invention.

[0039] Figure 3 The diagram illustrates the control principle of a collaborative scheduling controller for a symmetrical balanced modular parallel welding system with common-track scheduling, provided by an exemplary embodiment of the present invention.

[0040] Figure 4 The diagram illustrates a mirrored collaborative control logic block diagram of a collaborative scheduling controller for a symmetric balanced modular parallel welding system with common-track scheduling, provided by an exemplary embodiment of the present invention.

[0041] Figure 5 The diagram illustrates a flow chart of a symmetric balanced modular parallel welding method with common track scheduling, provided by an exemplary embodiment of the present invention.

[0042] In the diagram: 1. Gantry machine tool protective frame; 2. Collaborative scheduling controller; 3. Workpiece to be welded; 4. X-axis linear guide; 5. Column; 6. Modular welding unit; 7. Z-axis linear guide; 8. Y-axis linear guide. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] Figure 1 This diagram illustrates a structural schematic of a symmetric balanced modular parallel welding system with common-track scheduling, provided by an exemplary embodiment of the present invention. Figure 2This diagram illustrates the structure of a modular welding unit in a symmetrically balanced, modular, parallel welding system with shared-track scheduling, according to an exemplary embodiment of the present invention. The system includes: a gantry-type machine tool protective frame 1, on which an X-axis linear guide rail 4 is mounted, capable of moving vertically parallel to the column 5 of the gantry-type machine tool protective frame 1; at least two pairs of structurally identical modular welding units 6 are mounted on the X-axis linear guide rail 4, each modular welding unit 6 being disposed on both sides of the X-axis linear guide rail 4 and capable of moving independently along the X-axis linear guide rail 4; each modular welding unit 6 includes a slide 61, a three-axis fine-tuning platform 62, a welding torch 63, and a six-dimensional force sensor 64. The slide 61 is slidably connected to the X-axis linear guide rail 4, and the welding torch 63 is mounted on the slide 61. 1. The welding torch 63 has its torch head mounted on its body via a three-axis fine-tuning platform 62 for adjusting the torch head's posture. A six-dimensional force sensor 64 is mounted on the top of the welding torch 63 to collect real-time data on the contact pressure and torque applied by the welding torch 63 during the welding process. A collaborative scheduling controller 2 is connected to all modular welding units 6 and is configured to control the paired modular welding units 6 to operate in mirror mode. In mirror mode, the collaborative scheduling controller 2 drives two symmetrically arranged modular welding units 6 to move synchronously towards or away from each other at symmetrical positions on the workpiece 3 to be welded. It synchronously controls the welding parameters and applied contact forces of the two modular welding units 6, ensuring that the heat input and mechanical force of the two units on the workpiece 3 to be welded are equal in magnitude and opposite in direction, thereby achieving dynamic force-thermal balance in the welding process.

[0046] In this embodiment, the column 5 of the gantry machine tool protective frame 1, in conjunction with the vertically movable X-axis linear guide 4, adapts to the welding requirements of workpieces 3 of different thicknesses. Modular welding units 6 arranged on both sides of the X-axis linear guide 4 achieve parallel operation of multiple units through independent movement design, significantly improving welding efficiency. The modular structure facilitates later maintenance, replacement, and expansion, reducing equipment operation and maintenance costs. The three-axis fine-tuning platform 62 in each modular welding unit 6 can correct the posture of the welding torch 63 head, ensuring precise welding position. The six-dimensional force sensor 64 collects force and torque data in real time, providing data support for dynamic adjustment. The collaborative scheduling controller 2 controls the synchronous movement and parameter adjustment of paired modular welding units 6 at symmetrical positions on the workpieces 3 through mirror mode. Utilizing the principle of force-thermal counteraction, it suppresses welding deformation and residual stress from the source. Its communication connection with each modular welding unit 6 enables intelligent collaboration throughout the entire process.

[0047] In some embodiments, see Figure 1The gantry machine tool protective frame 1 has Z-axis linear guides 7 on both sides of the uprights 5. The two ends of the X-axis linear guide 4 are slidably engaged with the Z-axis linear guides 7 on both sides of the uprights 5 to achieve parallel displacement adjustment of the X-axis linear guide 4 in the vertical direction, adapting to workpieces 3 of different thicknesses to be welded. The workpiece 3 to be welded is placed on the Y-axis linear guide 8, which is located at the bottom inner side of the gantry machine tool protective frame 1. The X-axis linear guide 4 has two pairs of modular welding units 6 with four identical structures. The four modular welding units 6 are evenly distributed on the left and right sides of the X-axis linear guide 4. The two modular welding units 6 on each side can move independently along the X-axis linear guide 4 and form a mirror pair with the corresponding modular welding units 6 on the opposite side.

[0048] In this embodiment, the Z-axis linear guide 7 on the two side columns 5 of the gantry machine tool protective frame 1 slides with the X-axis linear guide 4, which can drive the X-axis linear guide 4 to achieve vertical parallel displacement, flexibly adapting to the welding height requirements of workpieces 3 of different thicknesses. The Y-axis linear guide 8 is located at the bottom inner side of the gantry machine tool protective frame 1 and is used to support the workpiece 3 to be welded. It can drive the workpiece 3 to be welded to move along the Y-axis, and cooperate with the modular welding unit 6 to achieve comprehensive welding of long or multi-weld workpieces, improving the work coverage. The two pairs of four modular welding units 6 deployed on the X-axis linear guide 4 are symmetrically distributed and can move independently along the X-axis linear guide 4. Their mirror pairing design can enhance the force and heat balance effect and reduce welding deformation; the parallel operation of the four modular welding units 6 can greatly improve the welding efficiency of multi-weld workpieces, and the independent movement characteristic can flexibly adapt to different weld layouts, further enhancing the production flexibility of the system.

[0049] In some embodiments, see Figure 1 and Figure 2 The three-axis fine-tuning platform 62 is an XYZ three-axis servo fine-tuning platform used to realize the displacement adjustment and angle attitude adjustment of the welding torch 63 head in three orthogonal directions; the signal output end of the six-dimensional force sensor 64 is connected to the collaborative scheduling controller 2 for feeding back the real-time collected contact pressure and torque data to the collaborative scheduling controller 2.

[0050] In this embodiment, the three-axis fine-tuning platform 62 adopts an XYZ three-axis servo control design, which can realize fine-tuning of the displacement and angle attitude of the welding torch 63 head in three orthogonal directions. It can compensate for assembly deviations of the workpiece 3 to be welded and positional offsets during the welding process, and ensure that the attitudes of the paired mirror-image welding torch 63 heads are completely synchronized, effectively avoiding welding defects caused by welding torch head attitude deviations. The six-dimensional force sensor 64 establishes a communication connection with the collaborative scheduling controller 2 to build a real-time feedback channel for the welding process. It transmits the pressure and torque data of the welding torch 63 in contact with the workpiece to the collaborative scheduling controller 2 in real time, ensuring that the force and heat input of the paired modular welding unit 6 remains balanced at all times, while avoiding excessive pressure on the welding torch 63 that could damage the workpiece 3 to be welded or insufficient pressure that could affect the welding quality.

[0051] In some embodiments, Figure 3 The diagram illustrates the control principle of a collaborative scheduling controller for a symmetrical balanced modular parallel welding system with shared track scheduling, provided by an exemplary embodiment of the present invention. The collaborative scheduling controller 2 is a distributed motion control system based on EtherCAT real-time industrial Ethernet, including an industrial PC as the master station and a motion control core. The industrial PC is connected to the servo driver slave station of each modular welding unit 6 via a single EtherCAT bus. The servo motor of the three-axis fine-tuning platform 62 and the six-dimensional force sensor 64 of each modular welding unit 6 are connected to the local servo driver of the corresponding modular welding unit 6 to realize the synchronous periodic command issuance and real-time feedback data acquisition of multiple modular welding units 6. The motion control core includes: a core control unit, which uses a high-performance motion control chip or motion control board to carry the motion control algorithm, parse the synchronous control commands issued by the industrial PC, and generate control signals; a real-time communication interface module, which is adapted to EtherCAT real-time industrial Ethernet, and is responsible for receiving the overall commands from the industrial PC, synchronously sending control signals to each servo drive, and receiving sensor data and motor operating status data fed back by the servo drives; and a data processing module, which is used to quickly process the real-time data fed back by each modular welding unit 6, including the contact pressure and torque data collected by the six-dimensional force sensor 64, and the operating parameters of the servo motor of the three-axis fine-tuning platform 62. After filtering and analyzing the data, it is fed back to the industrial PC to provide data support for the industrial PC to adjust the control strategy and maintain force and heat balance, and at the same time, it works with the core control unit to complete the real-time adjustment of closed-loop control.

[0052] In this embodiment, the collaborative scheduling controller 2 adopts a distributed architecture based on EtherCAT real-time industrial Ethernet. A single bus connects the industrial PC (master station) and the servo drive slave stations of each modular welding unit 6, significantly reducing communication latency and ensuring the synchronization of command issuance and data acquisition. The modules of the motion control core work collaboratively. The core control unit uses high-performance chips or boards to carry algorithms, parses industrial PC commands, and generates control signals. The real-time communication interface module adapts to the EtherCAT bus, establishing an efficient communication bridge between the master station and slave stations. The data processing module quickly processes real-time data from the six-dimensional force sensor 64 and the servo motor of the three-axis fine-tuning platform 62, filters and analyzes it, and feeds it back to the industrial PC. Simultaneously, it works with the core control unit to complete closed-loop regulation, ensuring the stability and accuracy of the welding process.

[0053] In some embodiments, Figure 4This diagram illustrates a mirror-coordinated control logic block diagram of a coordinating controller for a symmetrical balanced modular parallel welding system with shared-track scheduling, provided by an exemplary embodiment of the present invention. The coordinating controller 2 is configured to execute multi-level mirror-coordinated control logic, which includes a global coordination layer, a motion synchronization layer, a force-thermal coupling control layer, an adaptive adjustment layer, and a safety monitoring and fault tolerance layer that interact sequentially. The global coordination layer receives the CAD model and welding process library data of the workpiece 3 to be welded, completes welding task planning and symmetrical welding path generation, and issues welding path and synchronization control commands to the motion synchronization layer. The motion synchronization layer, based on the received symmetrical welding path, completes spatial mirror coordinate mapping and multi-axis motion time synchronization control. Based on the EtherCAT distributed clock synchronization mechanism and electronic gear synchronization strategy, it drives the paired modular welding units 6 to achieve mirror symmetry of spatial position and microsecond-level synchronization of motion. The force-thermal coupling control layer is configured to execute dual closed-loop control logic, with the inner loop being contact force closed-loop control, employing a PID and speed feedforward compensation control algorithm, and a real-time feedback data adjustment module based on a six-dimensional force sensor 64. The contact force of the two paired modular welding units 6 is adjusted to ensure that the contact forces of the two units are equal in magnitude and opposite in direction. The outer loop is a closed-loop control for heat input, using an incremental PID control algorithm to synchronously adjust the welding process parameters of the two paired modular welding units 6, ensuring that the heat input of the two units to be welded is consistent. At the same time, a feedforward decoupling strategy is used to eliminate the coupling interference between force control and heat control. The adaptive adjustment layer is used to dynamically adjust the control parameters of the paired modular welding units 6 based on real-time sensor data during the welding process. The control parameters include contact force, welding process parameters, and motion parameters. The system employs a dynamic speed control mechanism to suppress disturbances during the welding process. A least-squares stiffness identification model is used to detect the local stiffness of the workpiece to be welded online. When a difference in local stiffness is detected in the workpiece 3, the force or heat input ratio of the symmetrical modular welding unit 6 is automatically adjusted according to a stiffness matching strategy to maintain dynamic force-thermal balance during the welding process. A safety monitoring and fault-tolerant layer is used to monitor the operating status, welding parameters, and sensor data of each modular welding unit 6 in real time. When abnormal data or equipment failure is detected, an abnormal alarm process and a preset fault-tolerant processing process are executed to ensure system operational safety.

[0054] In this embodiment, the global collaboration layer receives the CAD model and process library data of the workpiece 3 to be welded, completes task planning and symmetrical path generation, and avoids welding path deviation. The motion synchronization layer achieves microsecond-level time synchronization and spatial mirror mapping, ensuring that the motion posture and position of the paired modular welding units 6 are completely symmetrical. The force-thermal coupling control layer uses dual closed-loop control, combined with feedback from the six-dimensional force sensor 64, to adjust the contact force and heat input, suppressing welding deformation from the source. The adaptive adjustment layer can cope with welding disturbances and local stiffness differences of the workpiece 3 to be welded, dynamically optimize control parameters, and maintain force-thermal balance stability. The safety monitoring and fault tolerance layer monitors the system operation status in real time, handles anomalies and faults in a timely manner, and avoids equipment damage or welding defects.

[0055] In some embodiments, the collaborative scheduling controller 2 is further configured to, during the welding process, control the three-axis fine-tuning platform 62 of each modular welding unit 6 to adaptively adjust the posture of the welding torch 63 head according to the real-time direction of the weld seam, so that the welding torch 63 head angles of the paired modular welding units 6 remain consistent.

[0056] In this embodiment, the collaborative scheduling controller 2 senses the weld seam direction in real time during the welding process. By adjusting the three-axis fine-tuning platform 62 of each modular welding unit 6, it achieves adaptive correction of the welding torch 63's head posture, ensuring that the welding torch 63's head angles of the paired modular welding units 6 are always consistent. This avoids posture deviations caused by weld seam direction offsets, thereby ensuring that the heat input and mechanical force of the welding on both sides are always symmetrical, consolidating the force-thermal balance effect. At the same time, this setting can compensate for workpiece assembly deviations or positional disturbances during the welding process, reducing defects such as weld seam offset and incomplete penetration, and improving the consistency of welding quality.

[0057] In one example, in the multi-level mirror collaborative control logic executed by the collaborative scheduling controller 2, the microsecond-level synchronization of the motion synchronization layer is achieved by adopting a distributed clock DC synchronization mechanism based on EtherCAT real-time industrial Ethernet to realize the microsecond-level motion synchronization of the paired modular welding units 6. The specific steps are as follows:

[0058] Clock reference calibration: The industrial PC acts as the EtherCAT master station. First, it performs initial clock offset compensation on all servo drive slave stations on the bus. Then, it measures the transmission delay between the master station and each slave station through ARP frames and compensates the system clock of each slave station.

[0059] Mirror coordinate transformation: A mirror coordinate system is established with the workpiece's center of symmetry as the origin. The welding path trajectory points generated by the global collaboration layer are transformed into the corresponding trajectory points of the paired modular welding unit 6 through coordinate mirror transformation, ensuring that the motion trajectories of the two are completely symmetrical about the workpiece's center of symmetry.

[0060] Synchronous motion control adopts a fixed interpolation cycle of 125 motion control. The master station sends the interpolated position command to the servo driver of the paired modular welding unit 6 through the EtherCAT bus. The paired modular welding unit 6 adopts a master-slave electronic gear synchronization mode. The position command of the slave axis is completely mirrored and synchronized with the master axis. At the same time, speed feedforward and acceleration feedforward compensation are introduced to eliminate motion lag of the servo system.

[0061] In one example, the multi-level mirrored cooperative control logic executed by the cooperative scheduling controller 2 uses force-thermal coupling dual closed-loop control. The inner loop is a contact force closed loop, and the outer loop is a thermal input closed loop. The specific control algorithm is as follows:

[0062] The inner-loop contact force closed-loop control adopts a PID control algorithm with velocity feedforward compensation, and the control law is as follows:

[0063] ;

[0064] Where e(t) is the target contact force F ref The actual contact force F collected in real time by the six-dimensional force sensor fb The difference; K p is a proportionality constant, ranging from 0.8 to 2.5 N / μm; K i is the integral coefficient, with a value ranging from 0.1 to 0.5 N / (μm·ms); K d is the differential coefficient, with a value range of 0.05~0.2 N·ms / μm; F ff For the velocity feedforward compensation, F ff =K v ·v(t), K v The velocity feedforward coefficient ranges from 0.3 to 1 N·s / mm, and v(t) is the real-time movement speed of the welding torch. The two paired modular welding units 6 have preset target contact forces that are equal in magnitude and opposite in direction. The Z-axis displacement of the three-axis fine-tuning platform 62 is adjusted in real time through the above control law to achieve closed-loop control of the contact force.

[0065] The outer loop heat input closed-loop control adopts an incremental PID control algorithm, with the welding heat input as the control objective. The formula for calculating the welding heat input is as follows:

[0066] ;

[0067] Where η is the welding thermal efficiency (0.7~0.85 for MIG / MAG welding), U is the welding voltage, I is the welding current, and v is the welding speed. During the control process, the difference in heat input ΔQ=Q1-Q2 between the paired modular welding units 6 is used as the control object. The welding current, voltage or welding speed is adjusted in real time through an incremental PID algorithm to ensure that |ΔQ|≤5J / mm, so that the heat input on both sides is completely consistent.

[0068] The force-heat coupling decoupling strategy adopts a feedforward decoupling method to establish a correlation model between the change of welding torch contact force and the torch extension length and welding heat input. When the closed-loop adjustment of the contact force causes the welding torch extension length to change, the current and voltage compensation commands are sent to the welding power source in advance to eliminate the interference of the extension length change on the heat input, thereby achieving complete decoupling of contact force control and heat input control and avoiding mutual influence between the two closed-loop controls.

[0069] In one example, in the multi-level mirrored cooperative control logic executed by the cooperative scheduling controller 2, the local stiffness of the workpiece to be welded is detected online through a least-squares stiffness identification model in the adaptive adjustment layer, including:

[0070] The workpiece local stiffness detection method is based on real-time feedback data from a six-dimensional force sensor 64 and a three-axis fine-tuning platform 62. It employs a least-squares stiffness identification model to achieve online detection of local stiffness. The local stiffness calculation formula is as follows:

[0071] ;

[0072] Wherein, ΔF is the change in contact force collected by the six-dimensional force sensor 64, and Δx is the change in displacement of the three-axis fine-tuning platform 62 in the direction of contact force; during the welding process, ΔF and Δx data for 5 consecutive cycles are collected with a sampling period of 1ms, and the local stiffness k value of the current welding position is obtained by fitting with the least squares method, thus completing the online real-time detection of the local stiffness of the workpiece.

[0073] In one example, in the multi-level mirrored collaborative control logic executed by the collaborative scheduling controller 2, when a difference in local stiffness of the workpiece 3 to be welded is detected in the adaptive adjustment layer, the force or heat input ratio of the symmetrical modular welding unit 6 is automatically adjusted according to the stiffness matching strategy, including:

[0074] When the local stiffness ratio k1 / k2 of the two paired welding positions is detected to exceed the preset range of 0.8~1.2, it is determined that there is a difference in the local stiffness of the workpiece. At this time, the heat input of the side with lower stiffness is used as the reference, and the heat input of the side with higher stiffness is linearly adjusted according to the stiffness ratio, with the adjustment ratio being k1 / k2. At the same time, the contact force on both sides is adjusted accordingly to make the contact force positively correlated with the local stiffness, ensuring that the welding deformation on both sides of the workpiece is consistent, and always maintaining the dynamic force-thermal balance in the welding process.

[0075] Figure 5 The diagram illustrates a flowchart of a common-track scheduling symmetric balanced modular parallel welding method according to an exemplary embodiment of the present invention. This common-track scheduling symmetric balanced modular parallel welding method is applied to the aforementioned common-track scheduling symmetric balanced modular parallel welding system. The method includes:

[0076] Step S1: The collaborative scheduling controller 2 loads the CAD model and welding process library of the workpiece 3 to be welded, and generates a symmetrical welding path and welding process parameters.

[0077] In this embodiment, this step integrates design data and process data. The symmetrical welding path generated based on the integrated data can accurately match the weld layout characteristics of the workpiece. The customized welding process parameters take into account the characteristics of the workpiece material and thickness, ensuring the technical requirements of symmetrical welding and improving the rationality and feasibility of the welding scheme.

[0078] Step S2: The collaborative scheduling controller 2 starts the mirror welding mode and controls the two paired modular welding units 6 to move to the symmetrical starting position of the weld seam of the workpiece 3 to be welded.

[0079] In this embodiment, this step ensures that the starting points of the welding units on both sides are completely symmetrical, avoiding the problem of force and heat imbalance caused by the asymmetry of the initial position.

[0080] Step S3: The collaborative scheduling controller 2 drives the paired modular welding units 6 to move synchronously towards or away from each other along the symmetrical welding path, and synchronously controls the welding parameters and applied contact force of the two modular welding units 6 so that the heat input and mechanical force of the workpiece 3 to be welded are equal in magnitude and opposite in direction.

[0081] In the embodiments of this application, this step achieves coordination of welding actions and can suppress welding deformation.

[0082] Step S4: During the welding process, the contact pressure and torque data of each modular welding unit 6 are collected in real time by the six-dimensional force sensor 64, and the dynamic force and heat balance of the paired modular welding units 6 is maintained by closed-loop regulation.

[0083] In this embodiment, this step effectively addresses real-time fluctuations during the welding process, ensuring a stable force-thermal balance of the paired modular welding units 6, thereby guaranteeing the controllability of the welding process and the consistency of welding quality.

[0084] Step S5: During the welding process, the weld direction and local stiffness changes of the workpiece 3 to be welded are detected in real time, and the welding torch 63 of the paired modular welding unit 6 is adaptively adjusted in terms of torch tip posture, contact force and heat input parameters to maintain the symmetrical balance of the welding process.

[0085] In the embodiments of this application, this step significantly improves the system's adaptability to complex welding conditions, ensuring the welding stability and quality of long-sized, complex welds and workpieces with local differences.

[0086] To verify the effectiveness of the technical solution of this invention in controlling welding deformation of long, thin-walled parts, and to quantitatively compare the differences in welding deformation and residual stress between this invention and existing technologies, the following experiments were conducted to demonstrate this:

[0087] Test workpiece: Hydrogen fuel cell metal bipolar plate, made of 316L austenitic stainless steel, with a plate thickness of 0.1mm, a total length of 800mm, and two parallel long straight welds with an effective length of 750mm for each weld.

[0088] Welding process: MAG pulse welding is adopted, the shielding gas is 98% Ar and 2% O2, and the unified welding standard parameters are welding current 120A, welding voltage 18V, welding speed 800mm / min, and wire feed speed 5m / min.

[0089] Testing equipment: coordinate measuring machine (measurement accuracy 0.5μm), X-ray residual stress meter, high-precision six-dimensional force sensor.

[0090] Option 1 (existing conventional technology): continuous welding with a single robot and a single welding gun, using rigid clamps to fix both ends of the workpiece, without symmetrical balance control;

[0091] Option 2 (existing dual-machine welding technology): Two welding robots with independent guide rails perform symmetrical welding, move synchronously towards each other, without shared rail coordination and force-thermal closed-loop control;

[0092] Scheme 3 (Technical Solution of the Invention): The common-track scheduling symmetrical balanced modular parallel welding system of this application is adopted. Two pairs of modular welding units are mirror-paired and weld synchronously in opposite directions, executing the force-heat dual closed-loop control and dynamic force-heat balance strategy of this application.

[0093] After all the welding was completed, the clamps were loosened and the samples were placed in an environment with a room temperature of 25°C and a humidity of 50% for 24 hours before testing.

[0094] Welding deformation test: A coordinate measuring machine is used to scan the entire plane of the workpiece, and the height data of 100×20 measuring points on the workpiece surface are collected. The maximum warping height (flatness deformation) of the workpiece and the total longitudinal shrinkage of the weld are calculated.

[0095] Residual stress test: The residual stress value in the central area of ​​the weld was tested using an X-ray stress meter. Five points were tested for each weld and the average value was taken.

[0096] The experimental results are shown in the table below:

[0097] Test Project Option 1 Option 2 Option 3 The reduction in deformation compared to Scheme 1 Maximum flatness warpage of the workpiece 2.36mm 0.98mm 0.68mm 71.2% Total longitudinal shrinkage of weld 0.82mm 0.35mm 0.22mm 73.2% Maximum residual stress in weld area 328MPa 186MPa 92MPa 71.9%

[0098] The above test data clearly demonstrate that, compared with existing conventional single-robot welding technology, the technical solution of the present invention reduces the overall welding deformation of the workpiece by more than 70%, while significantly reducing residual stress.

[0099] In summary, this technical solution, through a source-based symmetrical force-heat offsetting design, can reduce the overall welding deformation of the workpiece by more than 70%, while effectively reducing residual stress, ensuring welding accuracy and workpiece structural stability, and fundamentally solving the welding deformation problem of long, thin-walled parts. Furthermore, the adoption of a multi-modal parallel operation mode significantly shortens the welding time for long welds, enabling near-synchronous welding of multi-weld workpieces, significantly improving production efficiency and reducing production costs. Relying on modular and software-defined operating modes, it can quickly adapt to the needs of multi-variety and variable-batch production, reducing investment in specialized tooling, shortening production changeover time, and improving production flexibility. In addition, by integrating a multi-sensor closed-loop feedback mechanism, it can perceive dynamic changes in the welding process in real time, achieving intelligent real-time matching of process parameters and effectively broadening the process window.

[0100] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand this disclosure, and are not intended to limit the scope of the invention.

[0101] It is understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this disclosure.

[0102] It is understood that the various implementation methods described in this specification can be implemented individually or in combination, and this disclosure does not limit them.

[0103] Unless otherwise stated, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this specification. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0104] In the several embodiments provided in this specification, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the embodiments of the systems described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between systems or units may be electrical, mechanical, or other forms.

[0105] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0106] In addition, the functional units in the various embodiments of this specification can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0107] The above description is merely a specific embodiment of this specification, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this specification should be included within the scope of protection of this specification. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A symmetrical balanced modular parallel welding system with common-track scheduling, characterized in that, include: A gantry-type machine tool protective frame is provided with an X-axis linear guide rail, which can move parallel up and down along the columns of the gantry-type machine tool protective frame. At least two pairs of identical modular welding units are provided on the X-axis linear guide rail, each modular welding unit being located on both sides of the X-axis linear guide rail and capable of independent movement along the X-axis linear guide rail. Each modular welding unit includes a slide, a three-axis fine-tuning platform, a welding torch, and a six-dimensional force sensor. The slide is slidably connected to the X-axis linear guide rail, the welding torch is mounted on the slide, and the torch head is mounted on the torch body via the three-axis fine-tuning platform for adjusting the torch head's posture. The six-dimensional force sensor is mounted on the top of the welding torch for real-time acquisition of the contact pressure and torque data applied by the welding torch during the welding process. A collaborative scheduling controller, which is communicatively connected to all modular welding units, is configured to control the paired modular welding units to operate in a mirror mode. In the mirror mode, the collaborative scheduling controller drives two symmetrically arranged modular welding units to move synchronously towards or away from each other at symmetrical positions on the workpiece to be welded. It synchronously controls the welding parameters and applied contact forces of the two modular welding units, so that the heat input and mechanical force on the workpiece to be welded are equal in magnitude and opposite in direction, thereby achieving dynamic force-thermal balance in the welding process. The collaborative scheduling controller is configured to execute multi-level mirror collaborative control logic, which includes a global collaborative layer, a motion synchronization layer, a force-thermal coupling control layer, an adaptive adjustment layer, and a safety monitoring and fault tolerance layer that interact sequentially. The global collaboration layer is used to receive the CAD model of the workpiece to be welded and the welding process library data, complete the welding task planning and the generation of symmetrical welding paths, and send welding paths and synchronization control commands to the motion synchronization layer. The motion synchronization layer is used to complete spatial mirror coordinate mapping and multi-axis motion time synchronization control according to the received symmetrical welding path. Based on the EtherCAT distributed clock synchronization mechanism and electronic gear synchronization strategy, it drives the paired modular welding units to achieve mirror symmetry of spatial position and microsecond-level synchronization of motion. The force-thermal coupling control layer is configured to execute dual closed-loop control logic. The inner loop is a contact force closed-loop control, which uses a PID control algorithm with speed feedforward compensation. Based on the real-time feedback data of the six-dimensional force sensor, the contact force of the modular welding unit is adjusted so that the contact forces of the two paired modular welding units are equal in magnitude and opposite in direction. The outer loop is a heat input closed-loop control, which uses an incremental PID control algorithm to synchronously adjust the welding process parameters of the two paired modular welding units so that the heat input of the two units to be welded is consistent. At the same time, the coupling interference between force control and heat control is eliminated through a feedforward decoupling strategy. The adaptive adjustment layer is used to dynamically adjust the control parameters of the paired modular welding units based on real-time sensing data during the welding process. The control parameters include contact force, welding process parameters, and movement speed to suppress disturbances during the welding process. The local stiffness of the workpiece to be welded is detected online using a least squares stiffness identification model. When a difference in the local stiffness of the workpiece to be welded is detected, the force or heat input ratio of the symmetrical modular welding units is automatically adjusted according to the stiffness matching strategy to maintain the dynamic force and heat balance of the welding process. The safety monitoring and fault tolerance layer is used to monitor the operating status, welding parameters and sensor data of each modular welding unit in the system in real time. When abnormal data or equipment failure is detected, the abnormal alarm process and the preset fault tolerance process are executed to ensure the safe operation of the system.

2. The symmetrical balanced modular parallel welding system with common track scheduling according to claim 1, characterized in that, The protective frame of the gantry machine tool is equipped with Z-axis linear guides on both sides of the uprights. The two ends of the X-axis linear guides are slidably engaged with the Z-axis linear guides on both sides of the uprights to achieve parallel displacement adjustment of the X-axis linear guides in the vertical direction, which can accommodate workpieces of different thicknesses to be welded. The workpiece to be welded is placed on the Y-axis linear guide, which is located at the bottom inner side of the protective frame of the gantry machine tool.

3. The symmetrical balanced modular parallel welding system with common track scheduling according to claim 1, characterized in that, The X-axis linear guide rail is specifically equipped with two pairs of four identical modular welding units. The four modular welding units are evenly distributed on the left and right sides of the X-axis linear guide rail. The two modular welding units on each side can move independently along the X-axis linear guide rail and form a mirror pair with the corresponding modular welding unit on the opposite side.

4. The symmetrical balanced modular parallel welding system with common track scheduling according to claim 1, characterized in that, The three-axis fine-tuning platform is an XYZ three-axis servo fine-tuning platform, used to realize the displacement adjustment and angle attitude adjustment of the welding torch head in three orthogonal directions; The signal output terminal of the six-dimensional force sensor is communicatively connected to the collaborative scheduling controller, and is used to feed back the real-time collected contact pressure and torque data to the collaborative scheduling controller.

5. The symmetrical balanced modular parallel welding system with common-track scheduling according to any one of claims 1 to 4, characterized in that, The collaborative scheduling controller is a distributed motion control system based on EtherCAT real-time industrial Ethernet, including an industrial PC as the master station and a motion control core. The industrial PC is connected to the servo driver slave station of each modular welding unit through a single EtherCAT bus. The servo motor and six-dimensional force sensor of the three-axis fine-tuning platform of each modular welding unit are connected to the local servo driver of the corresponding modular welding unit to realize the synchronous periodic command issuance and real-time feedback data acquisition of multiple modular welding units.

6. The symmetrical balanced modular parallel welding system with common track scheduling according to claim 5, characterized in that, The motion control core includes: The core control unit, which uses a high-performance motion control chip or motion control board, is used to carry the motion control algorithm, and is responsible for parsing the synchronous control commands issued by the industrial PC and generating control signals. The real-time communication interface module is adapted to the EtherCAT real-time industrial Ethernet and is responsible for receiving the overall command of the industrial PC, while simultaneously sending control signals to each servo driver, and receiving sensor data and motor operating status data fed back by the servo drivers. The data processing module is used to quickly process real-time data fed back from each modular welding unit, including contact pressure and torque data collected by the six-dimensional force sensor, as well as the operating parameters of the servo motor of the three-axis fine-tuning platform. After filtering and analyzing the data, it feeds it back to the industrial PC, providing data support for the industrial PC to adjust the control strategy and maintain force and heat balance. At the same time, it works with the core control unit to complete the real-time adjustment of closed-loop control.

7. The symmetrical balanced modular parallel welding system with common-track scheduling according to any one of claims 1 to 4, characterized in that, The collaborative scheduling controller is also configured to, during the welding process, control the three-axis fine-tuning platform of each modular welding unit to adaptively adjust the posture of the welding torch head according to the real-time direction of the weld seam, so that the welding torch head angles of the paired modular welding units remain consistent.

8. A symmetric balanced modular parallel welding method with common track scheduling, characterized in that, The method is applied to the symmetric balanced modular parallel welding system with common track scheduling as described in claim 1, and the method includes: S1. The collaborative scheduling controller loads the CAD model and welding process library of the workpiece to be welded, and generates a symmetrical welding path and welding process parameters. S2. The collaborative scheduling controller starts the mirror welding mode and controls the two paired modular welding units to move to the symmetrical starting position of the weld seam of the workpiece to be welded. S3. The collaborative scheduling controller drives the paired modular welding units to move synchronously towards or away from each other along the symmetrical welding path, and synchronously controls the welding parameters and applied contact force of the two modular welding units, so that the heat input and mechanical force of the two units to be welded are equal in magnitude and opposite in direction. S4. During the welding process, the contact pressure and torque data of each modular welding unit are collected in real time by a six-dimensional force sensor, and the dynamic force and heat balance of the paired modular welding units is maintained through closed-loop regulation.

9. The symmetric balanced modular parallel welding method with common track scheduling according to claim 8, characterized in that, The method further includes: S5. During the welding process, the weld direction and local stiffness changes of the workpiece to be welded are detected in real time, and the welding torch tip posture, contact force and heat input parameters of the paired modular welding unit are adaptively adjusted to maintain the symmetrical balance of the welding process.

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