A multi-tube welding device and method for processing a tube truss

Abstract

This invention relates to the field of metal structure processing equipment technology, and discloses a multi-tube welding device and method for processing tubular trusses. The device includes a slide rail base, a gantry frame slidably connected to the outer side of the slide rail base, and welding robotic arms slidably connected to both sides of the gantry frame. A lifting mechanism is provided inside the slide rail base to support tubular trusses of different shapes. A clamping mechanism is provided in the middle of the slide rail base to clamp workpieces. A control panel is fixedly connected to the outer side of the slide rail base. The multi-tube welding device also includes a collaborative control mechanism, which consists of a main control module, a sensing module, and a compliant execution module. The main control module is located inside the control panel. This invention uses a compliant execution module to achieve dynamic yielding and follow-up pressure holding through thermal coupling, combined with an adjustable support mechanism, to release thermal stress and improve the assembly quality of irregularly shaped tubular materials.

Description

Technical Field

[0001] This invention relates to the field of metal structure processing equipment technology, specifically to a multi-tube welding device and method for processing tubular trusses. Background Technology

[0002] Tubular trusses are typically made of multiple steel pipes that intersect and are welded together. They are widely used in large-scale spatial load-bearing structures. In the existing tubular truss manufacturing process, gantry welding equipment is commonly used in conjunction with rigid fixtures to spatially position and weld the main and auxiliary rods.

[0003] However, this traditional processing method has some technical shortcomings in practical applications. Due to the concentrated heat input during the welding process at the junction of multiple pipes, the metal pipes will undergo significant thermal expansion. The current clamping and support mechanisms usually remain in a fixed mechanically locked state throughout the entire welding and cooling cycle, which cannot provide corresponding clearance space for the volume change of the pipes. As a result, the expansion and deformation of the pipes are directly converted into structural thermal stress inside the joint. When the welding ends and the cooling and shrinkage stage begins, the rigidly constrained support joints cannot provide a follow-up fitting and pressure-holding effect on the pipes. The thermal stress accumulated in the early stage will cause micro-cracks in the weld or cause overall dimensional deformation of the truss during the cooling process.

[0004] Furthermore, when processing complex irregular-shaped tubular trusses with arc-shaped or multi-layered spatial intersecting structures, the bearing surface of traditional support fixtures is relatively fixed, making it difficult to form a continuous and effective fit with the arc-shaped tube wall. When facing multi-layered intersecting nodes, existing equipment cannot provide flexible nested layered support, resulting in local suspended stress on the tubes during assembly. This not only increases the difficulty of early assembly alignment but also makes it difficult to ensure the stability of the welding reference. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-tube welding device and method for processing tubular trusses, which solves the problems that existing rigid welding fixtures cannot cope with thermal stress deformation caused by thermal expansion and contraction during welding, and that it is difficult to provide stable and close support for complex irregular tubular trusses.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides a multi-tube welding device for processing tubular trusses, including a slide rail base, a gantry frame slidably connected to the outer side of the slide rail base, welding robot arms slidably connected to both sides of the gantry frame; a lifting mechanism is provided on the inner side of the slide rail base for supporting tubular trusses of different shapes; a clamping mechanism is provided in the middle of the slide rail base for clamping workpieces; and a control panel is fixedly connected to the outer side of the slide rail base. The multi-pipe welding device also includes a collaborative control mechanism, which consists of a main control module, a sensing module, and a compliant execution module. The main control module is located inside the control panel, and the compliant execution modules are connected in series at the contact nodes of the lifting mechanism and the clamping mechanism at their respective stress ends. The sensing module is responsible for collecting the compressive stress data of the pipe contact surface and the surface temperature distribution data of the welding area, and transmitting the collected data back to the main control module. The main control module outputs electrical signals according to its built-in control logic to control the spatial position of the lifting mechanism and the clamping mechanism, as well as the displacement and stiffness changes of the compliant execution modules.

[0007] Preferably, the lifting mechanism includes a drive motor, which is fixed to the inner side of the slide rail seat, and a reduction gearbox is fixedly connected to the output end of the drive motor; a bidirectional threaded rod is rotatably connected to the inner side of the slide rail seat, and the output end of the reduction gearbox is fixedly connected to the bidirectional threaded rod; sliding blocks are threaded to both ends of the bidirectional threaded rod, and inclined blocks are fixedly connected to both sides of the inner side of the slide rail seat; a support plate is rotatably connected to the outer side of the sliding block, and the support plate is placed above the inclined block for support; a U-shaped block is rotatably connected to the end of the support plate; a pad is rotatably connected to the outer side of the U-shaped block, and pull-out plates are slidably connected to both sides of the pad.

[0008] Preferably, the clamping mechanism includes a rotating plate and a clamping drive unit for driving the rotating plate to rotate. The rotating plate is rotatably connected to the middle of the inner side of the slide rail seat. Pulling plates are rotatably connected to both ends of the rotating plate, and pressing plates are rotatably connected to the ends of the pulling plates. Limiting rails are fixedly connected to both ends of the slide rail seat, and the limiting rails are slidably connected to the inner side of the pressing plates.

[0009] Preferably, the sliding block moves axially along the bidirectional threaded rod to drive the support plate to slide relative to the inclined block for height adjustment; the pad is rotatably arranged relative to the U-shaped block to adapt to the curved surface support of the arc-shaped pipe truss; the pull-out plate can extend and retract along the length of the pad to extend below the positioned pipe to form a bottom support area for multiple layers of pipe.

[0010] Preferably, the extrusion plates are symmetrically distributed inside the slide rail seat. When the rotating plate rotates, the pulling plate drives the two sets of extrusion plates to move in opposite directions or away from each other along the defined rail to perform clamping or loosening actions on the workpiece.

[0011] Preferably, the sensing module includes an infrared scanner and a pressure sensor. The infrared scanner is disposed on one side of the welding robot arm to obtain heat-affected zone data, and the pressure sensor is attached to the inner contact surface of the clamping mechanism. The compliant actuation module includes a piezoelectric actuator and a magnetorheological damper.

[0012] Preferably, the main control module has a preset safety clamping force threshold. When the effective compressive stress data collected by the pressure sensor reaches the safety clamping force threshold, the main control module triggers the electromagnetic brake mechanism at the tail of the clamping drive unit of the clamping mechanism to act, so that the clamping mechanism forms a mechanical hard lock.

[0013] Preferably, during the welding heating process, the main control module calculates the required thermal expansion interference compensation amount at the current moment based on the temperature field data obtained by the infrared scanner; while the lifting mechanism and the clamping mechanism are mechanically locked, the main control module outputs a corresponding control voltage to the piezoelectric actuator to generate a contraction and retraction displacement, and simultaneously reduces the excitation current input to the magnetorheological damper to reduce the damping coefficient of the support node, thereby realizing the dynamic release of thermal stress.

[0014] Preferably, during the post-weld cooling period, when the main control module determines that the derivative of the temperature change rate of the heat-affected zone is continuously negative, the main control module gradually reduces the control voltage output to the piezoelectric actuator according to the absolute slope of the temperature drop, driving the piezoelectric actuator to slowly elongate following the cooling and contraction trend of the tube; and simultaneously increases the excitation current of the magnetorheological damper so that its damping coefficient returns to the reference locking state, thereby achieving pressure retention and adhesion of the weld area.

[0015] A second aspect of the present invention also provides a method for welding multiple tubes in the fabrication of a tubular truss, the method comprising the following steps: S1. Place the main rod above the clamping mechanism in the middle of the slide rail seat, and place the auxiliary rods crosswise on the side of the main rod, which are limited by the magnetic block at the top of the slide rail seat; start the clamping mechanism, and collect the real-time compressive stress data of the main rod contact surface through the pressure sensor of the sensing module. When the detected value reaches the preset safe clamping force threshold, the main control module controls the clamping drive unit in the clamping mechanism to perform mechanical locking. S2. The main control module drives the lifting mechanism to support and position the corresponding pipe fittings to a set height or set angle. During the positioning action, the driving voltage of the piezoelectric actuator in the compliant execution module remains zero, and the magnetorheological damper is in a high-damping reference locked state. After the positioning is completed, the main control module controls the lifting mechanism to perform mechanical locking. S3. The gantry crane drives the welding robot arm to perform arc welding along the intersection of the pipes. The infrared scanner of the sensing module acquires the temperature field data of the heat-affected zone. The main control module processes the data and extracts the effective distribution length and average temperature change rate of the current heat-affected zone. S4. During the welding heating process, the lifting mechanism and the clamping mechanism are kept in a mechanically locked state. The main control module outputs a control voltage to the piezoelectric actuator of the compliant execution module according to the calculated thermal expansion, so that it generates contraction and retraction. At the same time, the excitation current of the magnetorheological damper is reduced to reduce the damping coefficient, so that the node support surface generates a retraction displacement corresponding to the expansion of the pipe. S5. When the temperature of the heat-affected zone continues to drop, the main control module gradually reduces the control voltage of the piezoelectric actuator to make it slowly elongate. At the same time, the damping coefficient of the magnetorheological damper is returned to the reference locking state to achieve fitting and pressure holding. After the pipe is cooled and shaped, the main control module releases the mechanical locking state, and the pipe is flipped over by the lifting equipment and the welding process is repeated.

[0016] This invention provides a multi-tube welding apparatus and method for fabricating tubular trusses. It offers the following advantages: 1. In this invention, a compliant actuator module consisting of a piezoelectric actuator and a magnetorheological damper is connected in series at the contact node between the lifting mechanism and the clamping mechanism. During the welding heating stage, the main control module calculates the thermal expansion compensation of the pipe fitting based on the temperature field data collected by the infrared scanner, and then controls the piezoelectric actuator to generate micro-displacement contraction, while simultaneously reducing the damping coefficient of the magnetorheological damper. This thermo-coupling dynamic release mechanism can actively compensate for the volume expansion of the pipe caused by heating, release the internal thermal stress at the mechanically constrained node, and prevent the pipe from undergoing thermal deformation.

[0017] 2. This invention sets up a cooling follow-up shaping control logic based on temperature characteristics; during the post-weld cooling period, the main control module gradually reduces the control voltage of the piezoelectric actuator according to the temperature drop slope of the heat-affected zone, so that it slowly elongates following the cooling and shrinkage trend of the tube, while increasing the excitation current to make the magnetorheological damper return to the reference locking damping; this cooperative control method can provide continuous support force to the contact surface during the physical shrinkage stage of the tube, realize the fit and pressure retention of the weld area, and reduce the risk of structural cracks in the weld due to uncontrolled cooling and shrinkage.

[0018] 3. The lifting mechanism of the present invention adopts a transmission structure in which a bidirectional threaded rod drives a sliding block and an inclined block, and a rotatable U-shaped block, a pad, and a retractable pull plate are configured at the end of the support. Combined with the pressure feedback closed-loop control of the clamping mechanism, this mechanical configuration can not only perform surface follow-up rotation and fitting for arc-shaped pipe fittings to eliminate assembly gaps, but also perform nested pull-out bottom support for multi-layer quadrilateral pipe trusses, changing the suspended force state of large irregular pipe fittings when cross-positioned in multi-dimensional space, and improving the stability and assembly accuracy of the foundation support. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention; Figure 2 This is a front view of the present invention; Figure 3 This is a schematic diagram of the slide rail base of the present invention; Figure 4 This is a schematic diagram of the support plate of the present invention; Figure 5 This is a schematic diagram of the structure of the pad of the present invention; Figure 6 This is a cross-sectional view of the slide rail seat of the present invention; Figure 7 for Figure 6 A magnified view of point A; Figure 8 This is a block diagram illustrating the principle of the collaborative control system of the present invention; Figure 9 This is a flowchart of the control logic of the present invention.

[0020] The components include: 1. Slide rail base; 2. Gantry frame; 3. Welding robot arm; 4. Lifting mechanism; 41. Drive motor; 42. Gearbox; 43. Bidirectional threaded rod; 44. Sliding block; 45. Inclined block; 46. Support plate; 47. U-shaped block; 48. Pad plate; 49. Pull-out plate; 5. Clamping mechanism; 51. Rotating plate; 52. Pulling plate; 53. Pressing plate; 54. Limiting rail; 6. Control panel. Detailed Implementation

[0021] The technical solutions in 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.

[0022] Please see the appendix Figure 1 -Appendix Figure 9 This invention provides a multi-tube welding device for processing tubular trusses, including a slide rail seat 1, a gantry frame 2 slidably connected to the outside of the slide rail seat 1, welding robot arms 3 slidably connected to both sides of the gantry frame 2; a lifting mechanism 4 is provided on the inside of the slide rail seat 1, which is used to support tubular trusses of different forms; a clamping mechanism 5 is provided in the middle of the slide rail seat 1, which is used to clamp the workpiece; and a control panel 6 is fixedly connected to the outside of the slide rail seat 1. The multi-pipe welding device also includes a collaborative control mechanism, which consists of a main control module, a sensing module, and a compliant execution module. The main control module is located inside the control panel 6, and the compliant execution modules are connected in series at the contact nodes of the lifting mechanism 4 and the clamping mechanism 5 at the force-bearing ends. The sensing module is responsible for collecting the compressive stress data of the pipe contact surface and the surface temperature distribution data of the welding area, and transmitting the collected data back to the main control module. The main control module outputs electrical signals according to the built-in control logic to control the spatial position of the lifting mechanism 4 and the clamping mechanism 5, as well as the displacement and stiffness changes of the compliant execution modules. The lifting mechanism 4 includes a drive motor 41, which is fixed to the inside of the slide rail seat 1. A reduction gearbox 42 is fixedly connected to the output end of the drive motor 41. A bidirectional threaded rod 43 is rotatably connected to the inside of the slide rail seat 1. The output end of the reduction gearbox 42 is fixedly connected to the bidirectional threaded rod 43. Sliding blocks 44 are threaded to both ends of the bidirectional threaded rod 43. Inclined blocks 45 are fixedly connected to both sides inside the slide rail seat 1. A support plate 46 is rotatably connected to the outside of the sliding block 44. The support plate 46 is placed on top of the inclined block 45 for support. A U-shaped block 47 is rotatably connected to the end of the support plate 46. A pad 48 is rotatably connected to the outside of the U-shaped block 47. Pull-out plates 49 are slidably connected to both sides of the pad 48. The clamping mechanism 5 includes a rotating plate 51 and a clamping drive unit for driving the rotating plate 51 to rotate. The rotating plate 51 is rotatably connected to the middle of the inner side of the slide rail seat 1. Pulling plates 52 are rotatably connected to both ends of the rotating plate 51, and pressing plates 53 are rotatably connected to the ends of the pulling plates 52. Limiting rails 54 are fixedly connected to both ends of the slide rail seat 1, and the limiting rails 54 are slidably connected to the inner side of the pressing plates 53. The sliding block 44 moves axially along the bidirectional threaded rod 43 to drive the support plate 46 to slide relative to the inclined block 45 for height adjustment; the pad 48 is rotatably set relative to the U-shaped block 47 to adapt to the curved surface support of the arc-shaped pipe truss; the pull plate 49 can extend and retract along the length of the pad 48 to extend to the bottom of the positioned pipe to form a multi-layer pipe support area. The extrusion plates 53 are symmetrically distributed on the inner side of the slide rail seat 1. When the rotating plate 51 rotates, the pulling plate 52 drives the two sets of extrusion plates 53 to move in opposite directions or away from each other along the limiting rail 54 to perform the clamping or loosening action on the workpiece. The sensing module includes an infrared scanner and a pressure sensor. The infrared scanner is set on one side of the welding robot arm 3 to obtain data on the heat-affected zone, and the pressure sensor is attached to the inner contact surface of the clamping mechanism 5. The compliant actuation module includes a piezoelectric actuator and a magnetorheological damper. The main control module has a preset safety clamping force threshold. When the effective compressive stress data collected by the pressure sensor reaches the safety clamping force threshold, the main control module triggers the electromagnetic brake mechanism at the tail of the clamping drive unit of the clamping mechanism 5 to act, so that the clamping mechanism 5 forms a mechanical hard lock. During the welding heating process, the main control module calculates the required thermal expansion interference compensation based on the temperature field data obtained by the infrared scanner. While the lifting mechanism 4 and the clamping mechanism 5 are mechanically locked, the main control module outputs the corresponding control voltage to the piezoelectric actuator to generate a contraction and retraction displacement, and simultaneously reduces the excitation current input to the magnetorheological damper to reduce the damping coefficient of the support node, thereby realizing the dynamic release of thermal stress. During the post-weld cooling period, when the main control module determines that the derivative of the temperature change rate of the heat-affected zone is continuously negative, the main control module gradually reduces the control voltage output to the piezoelectric actuator according to the absolute slope of the temperature drop, driving the piezoelectric actuator to slowly elongate following the cooling and contraction trend of the tube; and simultaneously increases the excitation current of the magnetorheological damper to bring its damping coefficient back to the reference locking state, thereby achieving pressure retention and adhesion of the weld area. Specifically, in this embodiment, the operator or loading robot places the main rod on the bearing surface above the clamping mechanism 5 in the middle of the slide rail seat 1, and crosses the auxiliary rods at the intersection of the two sides of the main rod. The magnetic blocks set at the upper end of the slide rail seat 1 pre-limit the spatial position of the cross-placed auxiliary rods. The main rod and auxiliary rods maintain a relatively close fit under the combined action of gravity and magnetic attraction. The main control module sends a feed trigger signal to the servo drive unit configured inside the clamping mechanism 5 through the internal communication bus. The servo drive unit outputs rotational torque and drives the clamping plates on both sides of the clamping mechanism 5 to slide synchronously inward along the linear guide rail.

[0023] During the aforementioned closing motion, pressure sensors attached to the inner contact surface of the clamping plate collect transient compressive stress data in real time in the contact area between the clamping plate and the side wall of the main rod. The collected transient compressive stress data is fed back to the analog-to-digital conversion interface in the main control module in the form of an analog voltage signal for processing. Considering that electromagnetic interference or mechanical vibration at the moment of contact in the industrial site may cause high-frequency glitches in the transient compressive stress data, the main control module executes a sliding window filtering algorithm after receiving the data. The main control module calculates the average compressive stress within a set time window (in this embodiment, the set time window ranges from 50 milliseconds to 200 milliseconds) as the current effective compressive stress feedback. This signal processing mechanism reduces the probability of false triggering caused by abnormal pulse signals. The main control module executes subsequent servo self-locking control logic based on the processed effective compressive stress data.

[0024] As a preferred approach, the main control module is pre-configured with a safety clamping force threshold based on the specific physical characteristics of the pipe. The main control module switches the operating state of the clamping mechanism 5 in real time through a preset servo self-locking control logic. The state discrimination formula of this servo self-locking control logic is specifically set as follows: ; In the formula: This is a discrete control status word sent by the main control module to the servo drive unit. When the value of this variable is 1, it indicates that the servo drive unit continues to maintain the feed torque output state; when the value of this variable is 0, it indicates that the mechanical lock-up state is triggered. To enable the pressure sensor to detect the effective compressive stress value transmitted back at the current sampling time, The safety clamping force threshold parameter is retrieved from the main control module's memory.

[0025] In this embodiment, the safe clamping force threshold in the above formula is set to a range of 30% to 50% of the yield strength of the target pipe. This specific value is combined with the pipe wall thickness and material hardness to establish a mapping relationship table and stored in the main control module. When the main control module determines that the current effective compressive stress value reaches the safe clamping force threshold, the discrete control state word flips to zero and triggers the electromagnetic brake mechanism at the tail of the servo drive unit. The transmission system of the clamping mechanism 5 forms a mechanical hard lock under the locking action of the electromagnetic brake mechanism. The clamping mechanism 5 will no longer rotate in the opposite direction or fine-tune the feed in the same welding cycle. The electromagnetic brake action principle of the servo motor can be implemented by technicians using conventional electromechanical control theory in this embodiment.

[0026] In this embodiment, the main control module reads the pre-entered structural type parameters of the pipe fitting to be processed and sends a target displacement control command to the drive unit of the lifting mechanism 4. During this macroscopic positioning stage, the main control module simultaneously sends a reference state signal to the compliant execution module. The drive voltage of the piezoelectric actuator is set and maintained at zero value. The magnetorheological damper is subjected to a preset calibration excitation current (in this embodiment, the value range of the preset calibration excitation current is 1.5 amperes to 2.5 amperes) to be in a high-damping reference lock state. The control system makes the compliant execution module behave as a mechanical rigid connection body through the above electrical settings, so as to avoid the compliant component's movement clearance being superimposed on the large stroke space positioning value of the lifting mechanism 4. The lifting mechanism 4 performs a mechanical pushing action according to the received displacement command.

[0027] When the truss is triangular or curved, the main control module outputs a pulse sequence to drive the servo motor at the bottom of the lifting mechanism 4. The rotational torque of the servo motor is amplified by the reducer and transmitted to the bidirectional threaded rod 43. The rotation of the bidirectional threaded rod 43 drives the sliding block 44, which is connected to it, to slide inward along the thread. During the horizontal movement, the sliding block 44 presses the inclined structure of the inclined block 45. The supporting plate 46 and the U-shaped block 47 at the end are lifted upward along the vertical guide rail to the target assembly reference surface. As a preferred method, when facing the curved surface support scenario of the curved truss, the U-shaped block 47 deflects around the hinge axis connecting it to the supporting plate 46. The pad 48 inside the U-shaped block 47 rotates and fits after contacting the bottom surface of the pipe, offsetting the initial assembly gap of the basic support structure and forming a continuous surface contact force state in the bottom area of ​​the pipe.

[0028] When faced with the processing scenario of a quadrilateral tubular truss with a multi-layered spatial topology, the system calls the step-by-step lifting and pull-out support control logic. After completing the initial spatial positioning of the bottom basic tubular components, the main control module pauses the lifting drive of the lifting mechanism 4. The pad 48 deflects at ninety degrees and the pull-out plate 49 extends to the bottom of the positioned tubular components to form the bottom support area. The main control module then triggers the servo motor of the lifting mechanism 4 to run again, and continues to push the pad 48 to the assembly height range of the second-layer auxiliary tubular components by relying on the transmission cooperation of the bidirectional threaded rod 43 and the tilting block 45. The operator places the auxiliary tubular components on the upper and lower sides at the corresponding support node positions. This mechanical configuration, which combines layered independent control with nested sliding components, adapts to the cross-positioning settings of complex irregular trusses in multi-dimensional space, changing the suspended force state during the assembly of large tubular components.

[0029] At the completion node of single-layer support action or multi-layer step-by-step lifting action, the main control module receives the current lifting coordinates fed back by the position encoder and calculates the difference with the target assembly height. When the deviation value enters the preset approximation range (in this embodiment, the preset approximation range is within the physical travel range of five to ten millimeters above and below the target assembly height), the system executes the deceleration smoothing control algorithm. When the coordinate difference approaches zero, the main control module cuts off the feed pulse signal of the servo motor. The main control module simultaneously activates the electromagnetic brake configured at the tail end of the servo motor. This braking mechanism enables the transmission chain of the lifting mechanism 4 to form a mechanical locking circuit from the motor rotor end to the top U-shaped block 47 support end. The macroscopic mechanical locking state remains stable within the welding cycle of this single-side node. The mechanical locking circuit blocks the displacement drift phenomenon caused by the gear meshing clearance of the reduction gearbox 42 and the backlash of the thread pair under the subsequent welding thermal impact from the physical structure level. The main control module provides a welding reference platform through the locking operation and cooperates with the clamping mechanism 5 to maintain the topology of the pipe.

[0030] In this embodiment, the metal pipe in the arc ignition and welding heating stage will undergo volume expansion at the lattice scale due to the accumulation of heat input. Since the main control module controls the clamping mechanism 5 and the lifting mechanism 4 to maintain a fixed mechanical lock state at this time, the expansion deformation of the pipe will be converted into internal thermal stress at the constrained mechanical node. The main control module calculates the required structural micro-motion compensation amount at the current moment based on the temperature field data extracted in real time by the infrared scanner. The main control module converts the structural micro-motion compensation amount into the corresponding driving electrical signal and applies it to the compliant execution module at the end of the force.

[0031] The main control module internally runs a displacement compensation calculation algorithm and calculates the theoretical thermal expansion interference of the system. The analytical calculation formula for the displacement compensation is set as follows: ; In the formula: This is the amount of active micro-displacement compensation required at the current moment, calculated by the main control module. The linear thermal expansion coefficient is the value of the corresponding metal pipe retrieved by the system from its built-in material property library. The average ambient temperature of the heat-affected zone as acquired by the infrared scanner at the current moment. The initial room temperature of the environment was calibrated and recorded before the welding operation began. This represents the effective distribution length of the heat-affected zone extracted in the previous processing cycle. The overall structural stiffness reduction factor is set based on different truss topologies. As a preferred method, the value of this factor ranges from 0.7 to 0.85 when the processing object is a triangular space frame, and from 0.85 to 0.95 when the processing object is an arc-shaped space frame.

[0032] After obtaining the micro-displacement compensation amount, the main control module performs a mapping conversion operation to the physical drive parameters. The main control module converts the calculated micro-displacement compensation amount into the reverse drive voltage of the piezoelectric actuator. The voltage conversion calculation formula is set as follows: ; In the formula: This is the real-time control voltage value output to the piezoelectric actuator. This is the intrinsic inverse piezoelectric voltage constant of the piezoelectric ceramic material. The total number of piezoelectric ceramic layers stacked in parallel inside the piezoelectric actuator. Under the excitation of the input voltage signal, the piezoelectric actuator generates a corresponding physical microscopic contraction displacement. Under the premise that the macroscopic mechanical base remains locked, the node support surface generates a yield displacement at the force contact end that is equivalent to the thermal expansion of the tube.

[0033] When the main control module outputs the piezoelectric control voltage, it synchronously regulates the excitation current inside the magnetorheological damper connected in parallel to the support node. The main control module reduces the transient damping coefficient of the node support surface by decreasing the excitation current. The dynamic damping adjustment formula is set as follows: ; In the formula: The target damping coefficient calculated at the current moment. The benchmark locking damping coefficient is calibrated for the macro positioning stage, and its value ranges from 80% to 95% of the rated maximum damping coefficient of the magnetorheological damper. The system's preset temperature change rate damping response sensitivity coefficient ranges from 0.15 to 0.35; the formula incorporates a minimum safe damping lower limit parameter. Algorithm truncation protection is implemented, with the minimum safe damping lower limit parameter specifically set between 10% and 20% of the benchmark locking damping coefficient. This truncation mechanism prevents a sharp rise in temperature from causing the calculated damping value to approach zero or become negative, thereby leading to a complete loss of stiffness in the compliant execution node. The main control module, through this thermodynamic coupling control logic and the piezoelectric component, achieves non-contact frictional release of welding thermal stress.

[0034] In this embodiment, as the welding area of ​​the local intersection node gradually changes from a high-temperature plastic state to a room-temperature elastic state and enters the natural solidification and cooling period after the welding operation is completed, the infrared scanner continuously acquires the surface temperature distribution data of the area and transmits it back to the main control module. The main control module performs differential operation on the continuously sampled temperature data and monitors the positive and negative attributes of the derivative of the temperature change rate. When it is determined that the derivative of the temperature change rate of the heat-affected zone is continuously negative, the system enters the cooling follow-up shaping stage. Due to the removal of the heat source, the pipe undergoes macroscopic physical shrinkage of its internal lattice. The main control module simultaneously starts the follow-up reset compensation logic of the micro support node. This judgment mechanism based on the temperature derivative trend avoids the misjudgment phenomenon caused by single-point temperature fluctuations.

[0035] The main control module synchronously reduces the control voltage output to the piezoelectric actuator based on the real-time temperature drop curve fed back by the infrared scanner. The internal formula for the follow-up reset voltage of the main control module is set as follows: ; In the formula: This is the reset control voltage sent to the piezoelectric actuator in real time during the cooling phase. The effective average temperature of the heat-affected zone at the current moment. The system is preset with a safe demolding temperature threshold that allows the release of mechanical constraints. To extract the maximum effective distribution length of the locked heat-affected zone at the critical moment of welding cessation, the piezoelectric actuator elongates its internal piezoelectric ceramic wafer under the continuously decaying control voltage. This elongation displacement follows the cooling and contraction trajectory of the tube surface in physical space and provides continuous contact support force.

[0036] As a preferred approach, the safe demolding temperature threshold value called by the main control module in the above-mentioned follow-up reset voltage analysis formula is set to the initial ambient temperature plus a margin range of 20 to 30 degrees Celsius. During the process of reducing the control voltage of the piezoelectric actuator, the main control module synchronously adjusts the excitation current signal input to the magnetorheological damper. The main control module gradually increases the value of the excitation current according to the absolute slope of the temperature drop. The apparent shear yield stress of the magnetorheological fluid inside the magnetorheological damper increases accordingly with the increase of current. The damping coefficient of the node support surface then smoothly returns from the compliant state to the reference locking damping coefficient set in the macroscopic positioning stage. This damping return mechanism and the slow elongation action of the piezoelectric actuator form a synergistic state at the physical execution layer. The system applies a microscopic follow-up shaping and pressure holding effect to the pipe contact surface within the range of weld metal transformation to solid grains.

[0037] During the pressure holding cycle, the main control module continuously compares the current effective average temperature with the safe demolding temperature threshold. When it is determined that the current effective average temperature is lower than the safe demolding temperature threshold and the welding tasks of all set nodes on one side have been completed, the main control module cuts off the holding current of the electromagnetic brake inside the lifting mechanism 4 and the clamping mechanism 5. The transmission chain of the lifting mechanism 4 and the clamping mechanism 5 is released from the mechanical hard lock state and restored to the unlocked setting that can be freely driven. The externally configured lifting equipment lowers the lifting device and clamps the main frame of the pipe fitting according to the command of the control panel 6, flipping the pre-shaped pipe truss as a whole to the unprocessed surface. The main control module then resets the state parameters of each sensing unit and the actuator and repeatedly triggers the aforementioned positioning and thermal coupling control process until the entire pipe truss is closed-loop welded and formed.

[0038] The method for welding multiple tubes in the fabrication of tubular trusses described below can be referred to in correspondence with the multi-tube welding device for fabricating tubular trusses described above.

[0039] A method for fabricating multi-tube welding of tubular trusses, the method comprising the following steps: S1. Place the main rod above the clamping mechanism 5 in the middle of the slide rail seat 1, and place the auxiliary rods crosswise on the side of the main rod, which are limited by the magnetic block at the upper end of the slide rail seat 1; start the clamping mechanism 5, and collect the real-time compressive stress data of the main rod contact surface through the pressure sensor of the sensing module. When the detected value reaches the preset safe clamping force threshold, the main control module controls the clamping drive unit in the clamping mechanism 5 to perform mechanical locking. S2. The main control module drives the lifting mechanism 4 to support and position the corresponding pipe fittings to a set height or set angle. During the positioning action, the driving voltage of the piezoelectric actuator in the compliant execution module remains zero, and the magnetorheological damper is in a high-damping reference locked state. After the positioning is completed, the main control module controls the lifting mechanism 4 to perform mechanical locking. S3, the gantry 2 drives the welding robot arm 3 to perform arc welding along the intersection of the pipes. The infrared scanner of the sensing module acquires the temperature field data of the heat-affected zone. The main control module processes the data and extracts the effective distribution length and average temperature change rate of the current heat-affected zone. S4. During the welding heating period, the lifting mechanism 4 and the clamping mechanism 5 maintain a mechanically locked state. The main control module outputs a control voltage to the piezoelectric actuator of the compliant execution module according to the calculated thermal expansion amount, so that it generates contraction and retraction. At the same time, the excitation current of the magnetorheological damper is reduced to reduce the damping coefficient, so that the node support surface generates a retraction displacement corresponding to the expansion amount of the pipe. S5. When the temperature of the heat-affected zone continues to drop, the main control module gradually reduces the control voltage of the piezoelectric actuator to make it slowly elongate. At the same time, the damping coefficient of the magnetorheological damper is returned to the reference locking state to achieve fitting and pressure holding. After the pipe is cooled and shaped, the main control module releases the mechanical locking state, and the pipe is flipped over by the lifting equipment and the welding process is repeated.

[0040] The method in this embodiment can use the above-described embodiment of a multi-tube welding device for truss processing, and its principle and technical effects are similar, so they will not be repeated here.

[0041] Working principle: During the initial assembly stage of the workpiece, the operator or the feeding equipment places the main rod above the clamping mechanism 5 in the middle of the slide rail seat 1, and the auxiliary rod is placed on the side of the main rod. The magnetic block provides spatial pre-limitation. The main control module starts the clamping drive unit, which drives the rotating plate 51 to rotate. The rotating plate 51 drives the pressing plates 53 at both ends to slide inward along the limiting rail 54 through the pulling plate 52. The pressure sensor inside the pressing plate 53 collects the compressive stress data of the contact surface in real time and feeds it back to the main control module. When the compressive stress data reaches the system's preset safe clamping force threshold, the main control module triggers the electromagnetic brake mechanism at the tail of the clamping drive unit to act, so that the clamping mechanism 5 forms a mechanical hard lock, ensuring that the pipe is fixed on the assembly reference surface. During the classification support and macro positioning stage, the main control module drives the lifting mechanism 4 to operate according to the pre-entered pipe structure type parameters; the rotational torque of the drive motor 41 is transmitted to the bidirectional threaded rod 43 through the reduction gearbox 42, and the rotation of the bidirectional threaded rod 43 causes the sliding blocks 44 at both ends to move towards each other, and the sliding blocks 44 press the inclined block 45 to lift the support plate 46; for the arc-shaped pipe truss, the U-shaped block 47 and the pad 48 rotate to fit the bottom curved surface of the pipe; for the multi-layer quadrilateral pipe truss, the pull plate 49 extends along the pad 48 to form the bottom support of the lower pipe; during the positioning action, the input voltage of the piezoelectric actuator of the compliant execution module remains at zero, and the magnetorheological damper is supplied with the calibrated excitation current to maintain the high damping reference locking state; after positioning, the drive motor 41 of the lifting mechanism 4 performs the brake locking; During the welding and thermal coupling dynamic release phase, the gantry 2 drives the welding robot arm 3 to perform arc welding along the intersection of the pipes; the infrared scanner on the side of the welding robot arm 3 continuously acquires the temperature field distribution data of the heat-affected zone; the welding heating causes the metal pipe to expand in volume, and the main control module calculates the required thermal expansion compensation based on the extracted temperature field data; under the condition that the lifting mechanism 4 and the clamping mechanism 5 maintain macroscopic deadlock, the main control module outputs control voltage to the piezoelectric actuator, driving the piezoelectric ceramic inside the piezoelectric actuator to generate a contraction displacement, and simultaneously reduces the excitation current input to the magnetorheological damper to reduce the transient damping coefficient of the support node; the yield displacement generated by the node support surface offsets the volume expansion of the pipe, thereby releasing the internally accumulated structural thermal stress; During the cooling follow-up shaping and overall flipping stages, after welding is completed and the molten pool enters the natural solidification period, when the main control module determines that the derivative of the temperature change rate is continuously negative based on the data fed back by the infrared scanner, the main control module activates the cooling follow-up compensation logic. The main control module gradually reduces the control voltage of the piezoelectric actuator according to the temperature drop slope, driving the piezoelectric actuator to slowly elongate following the cooling and contraction trend of the pipe. At the same time, the main control module increases the excitation current input to the magnetorheological damper, so that the damping coefficient smoothly returns to the reference locking state. The elongation of the piezoelectric actuator and the return of the damping coefficient work together at the physical level to apply a micro-level follow-up shaping and pressure holding effect to the pipe contact surface. After the effective average temperature drops to the safe demolding temperature threshold and all welding processes on one side are completed, the main control module cuts off the holding current of the electromagnetic brake to release the mechanical constraint. After the pipe truss is flipped as a whole by the lifting equipment, the welding process is repeated to perform welding on the unprocessed surface.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-tube welding device for processing tubular trusses, comprising a slide rail seat (1), characterized in that, A gantry frame (2) is slidably connected to the outside of the slide rail base (1), and welding robot arms (3) are slidably connected to both sides of the gantry frame (2); a lifting mechanism (4) is provided on the inside of the slide rail base (1), and the lifting mechanism (4) is used to support different types of pipe trusses; a clamping mechanism (5) is provided in the middle of the slide rail base (1), and the clamping mechanism (5) is used to clamp the workpiece; a control panel (6) is fixedly connected to the outside of the slide rail base (1). The multi-pipe welding device also includes a collaborative control mechanism, which consists of a main control module, a sensing module, and a compliant execution module. The main control module is located inside the control panel (6), and the compliant execution module is connected in series at the contact nodes of the lifting mechanism (4) and the clamping mechanism (5). The sensing module is responsible for collecting the compressive stress data of the pipe contact surface and the surface temperature distribution data of the welding area, and transmitting the collected data back to the main control module. The main control module outputs electrical signals according to the built-in control logic to control the spatial position of the lifting mechanism (4) and the clamping mechanism (5) as well as the displacement and stiffness changes of the compliant execution module.

2. The apparatus according to claim 1, characterized in that, The lifting mechanism (4) includes a drive motor (41), which is fixed inside the slide rail seat (1). A reduction gearbox (42) is fixedly connected to the output end of the drive motor (41). A bidirectional threaded rod (43) is rotatably connected inside the slide rail seat (1). The output end of the reduction gearbox (42) is fixedly connected to the bidirectional threaded rod (43). Both ends of the bidirectional threaded rod (43) are threaded with sliding blocks (44). Inclined blocks (45) are fixedly connected to both sides inside the slide rail seat (1). A support plate (46) is rotatably connected to the outside of the sliding block (44). The support plate (46) is placed above the inclined block (45) for support. A U-shaped block (47) is rotatably connected to the end of the support plate (46). A pad (48) is rotatably connected to the outside of the U-shaped block (47). Pull-out plates (49) are slidably connected to both sides of the pad (48).

3. The apparatus according to claim 1, characterized in that, The clamping mechanism (5) includes a rotating plate (51) and a clamping drive unit for driving the rotating plate (51) to rotate. The rotating plate (51) is rotatably connected to the middle of the inner side of the slide rail seat (1). Pulling plates (52) are rotatably connected to both ends of the rotating plate (51), and pressing plates (53) are rotatably connected to the ends of the pulling plates (52). Limiting rails (54) are fixedly connected to both ends of the slide rail seat (1), and the limiting rails (54) are slidably connected to the inner side of the pressing plates (53).

4. The apparatus according to claim 2, characterized in that, The sliding block (44) moves axially along the bidirectional threaded rod (43) to drive the support plate (46) to slide relative to the inclined block (45) for height adjustment; the pad (48) is rotatably set relative to the U-shaped block (47) to adapt to the curved surface support of the arc-shaped pipe truss; the pull plate (49) can extend and retract along the length direction of the pad (48) to extend to the bottom of the positioned pipe to form a multi-layer pipe support area.

5. The apparatus according to claim 3, characterized in that, The extrusion plates (53) are symmetrically distributed on the inner side of the slide rail seat (1). When the rotating plate (51) rotates, the two sets of extrusion plates (53) are driven to move in opposite directions or away from each other along the limiting rail (54) by the pulling plate (52) to perform the clamping or loosening action on the workpiece.

6. The apparatus according to claim 1, characterized in that, The sensing module includes an infrared scanner and a pressure sensor. The infrared scanner is located on one side of the welding robot arm (3) to obtain data on the heat-affected zone. The pressure sensor is attached to the inner contact surface of the clamping mechanism (5). The compliant actuation module includes a piezoelectric actuator and a magnetorheological damper.

7. The apparatus according to claim 6, characterized in that, The main control module has a preset safety clamping force threshold. When the effective compressive stress data collected by the pressure sensor reaches the safety clamping force threshold, the main control module triggers the electromagnetic brake mechanism at the tail of the clamping drive unit of the clamping mechanism (5) to act, so that the clamping mechanism (5) forms a mechanical hard lock.

8. The apparatus according to claim 6, characterized in that, During the welding heating process, the main control module calculates the thermal expansion interference compensation required at the current moment based on the temperature field data obtained by the infrared scanner. While the lifting mechanism (4) and the clamping mechanism (5) are mechanically locked, the main control module outputs a corresponding control voltage to the piezoelectric actuator to generate a contraction and retraction displacement, and simultaneously reduces the excitation current input to the magnetorheological damper to reduce the damping coefficient of the support node, thereby realizing the dynamic release of thermal stress.

9. The apparatus according to claim 8, characterized in that, During the post-weld cooling period, when the main control module determines that the derivative of the temperature change rate of the heat-affected zone is continuously negative, the main control module gradually reduces the control voltage output to the piezoelectric actuator according to the absolute slope of the temperature drop, driving the piezoelectric actuator to slowly elongate following the cooling and contraction trend of the tube. Simultaneously, the excitation current of the magnetorheological damper is increased to bring its damping coefficient back to the reference locking state, thereby achieving pressure retention and bonding of the weld area.

10. A method for welding multiple tubes in the fabrication of a tubular truss, characterized in that, Using the multi-tube welding apparatus for fabricating tubular trusses according to any one of claims 1 to 9, the method comprises the following steps: S1. Place the main rod above the clamping mechanism (5) in the middle of the slide rail seat (1), and place the auxiliary rods crosswise on the side of the main rod. The magnetic block at the upper end of the slide rail seat (1) will limit the position. Start the clamping mechanism (5) and collect the real-time compressive stress data of the contact surface of the main rod through the pressure sensor of the sensing module. When the detected value reaches the preset safe clamping force threshold, the main control module controls the clamping drive unit in the clamping mechanism (5) to perform mechanical locking. S2. The main control module drives the lifting mechanism (4) to position the corresponding pipe support to the set height or set angle. During the positioning action, the driving voltage of the piezoelectric actuator in the compliant execution module remains zero, and the magnetorheological damper is in a high-damping reference locked state. After the positioning is completed, the main control module controls the lifting mechanism (4) to perform mechanical locking. S3, the gantry (2) drives the welding robot arm (3) to perform arc welding along the intersection of the pipe fittings. The infrared scanner of the sensing module obtains the temperature field data of the heat-affected zone. The main control module processes the data and extracts the effective distribution length and average temperature change rate of the current heat-affected zone. S4. During the welding heating period, the lifting mechanism (4) and the clamping mechanism (5) maintain a mechanically locked state. The main control module outputs control voltage to the piezoelectric actuator of the compliant execution module according to the calculated thermal expansion amount, so that it generates contraction and yielding. At the same time, the excitation current of the magnetorheological damper is reduced to reduce the damping coefficient, so that the node support surface generates a yielding displacement corresponding to the expansion amount of the pipe. S5. When the temperature of the heat-affected zone continues to drop, the main control module gradually reduces the control voltage of the piezoelectric actuator to make it slowly elongate. At the same time, the damping coefficient of the magnetorheological damper is returned to the reference locking state to achieve fitting and pressure holding. After the pipe is cooled and shaped, the main control module releases the mechanical locking state, and the pipe is flipped over by the lifting equipment and the welding process is repeated.

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