A magnetic control rotating arc welding equipment and arc stabilizing control method

Abstract

This invention belongs to the field of special welding equipment and automated control technology, specifically a magnetically controlled rotary arc welding equipment and arc stabilization control method. It acquires arc signals at high frequency and extracts in parallel the average DC voltage representing the macroscopic gap state and the voltage change rate dU / dt representing microscopic transient fluctuations. In the microscopic time dimension, when dU / dt abruptly exceeds the limit, the power supply side is directly triggered to output transient compensation energy to maintain arc stability. In the macroscopic spatial dimension, a servo mechanism is dynamically driven to perform micrometer-level physical displacement compensation based on the voltage mean deviation, maintaining a constant dynamic welding gap. When the cumulative compensation reaches a preset condition, a closed-loop full-power upsetting is triggered. Based on this, this invention effectively overcomes the problems of arc length drift and arc breakage caused by end-face burn-off and processing errors in pipe fittings through spatiotemporal decoupled collaborative control, significantly improving the consistency of welding quality.

Description

Technical Field

[0001] This invention relates to the field of special welding equipment and automated control technology, specifically to a magnetically controlled rotary arc welding equipment and an arc stabilization control method. Background Technology

[0002] Magnetic control rotary arc welding (MIAB) is a pressure arc welding method that uses electromagnetic force to drive the movement of an electric arc. Its working principle involves igniting an arc in the butt joint gap of the pipe fittings being welded. The Lorentz force generated by the interaction of an external magnetic field and the arc current drives the arc to rotate at high speed along the end face of the pipe fitting. Once the end face of the pipe fitting is heated to a molten state by the arc, upsetting pressure is rapidly applied to complete the connection.

[0003] Due to its advantages such as fast welding speed, concentrated heat input, small joint deformation, and no need to add filler material, MIAB welding has been widely used in the automated production of automobiles, pipe manufacturing, and hollow structural components.

[0004] In existing magnetically controlled rotary arc welding equipment, the initial gap of the pipe end face is usually preset by a mechanical limiting device, and open-loop control is performed using constant excitation current and welding current parameters. However, in the actual welding process, there are often slight machining errors or burrs on the pipe end face, and as the welding process progresses, the pipe end face is continuously burned off due to heat melting.

[0005] In traditional fixed-gap control mode, burn-off of the end face causes macroscopic drift in the actual arc length. Simultaneously, unevenness of the end face can lead to momentary instability or arc blow-off during high-speed rotation. Because existing equipment lacks real-time feedback and adjustment mechanisms for the physical state of the arc during welding, once the arc length deviates from the optimal process range, it is highly susceptible to arc interruption or uneven heating, thereby affecting the concentricity and connection strength of the weld joint and making it difficult to guarantee process consistency in large-scale production. Summary of the Invention

[0006] To address the limitations of existing magnetically controlled rotary arc welding technologies, which rely on mechanical fixed positioning and open-loop control, and are unable to handle arc length drift caused by end-face burn-out, as well as transient instability and arc interruption due to uneven end-face surfaces, this invention provides an adaptive magnetically controlled rotary arc welding equipment and arc stabilization control method. This invention achieves dynamic constancy of the welding physical gap and real-time stabilization of the arc state through decoupled and coordinated control of "macroscopic displacement servo compensation" and "microscopic power supply transient adjustment," effectively improving the consistency of weld joint quality.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for stabilizing the arc in magnetically controlled rotary arc welding includes the following steps: Step S1, Real-time perception of dual-dimensional features: After the welding arc is started, the voltage and current signals at the dynamic welding gap are collected in real time, and the average DC voltage representing the macro gap state and the voltage change rate dU / dt representing the micro arc transient fluctuation are extracted in parallel. Step S2, Spatiotemporal Dual-Dimensional Dynamic Arc Stabilization: During the welding heating stage, the system enters a high-frequency adaptive adjustment mode. Microscopic energy transient intervention: Real-time monitoring of the voltage change rate dU / dt. When it is determined that the sudden change of dU / dt exceeds the set threshold and there is a risk of arc extinction, the power supply side energy rescue response is immediately triggered, and transient compensation energy is output to maintain the microscopic stability of the arc. Macroscopic gap displacement servo: The average DC voltage value is compared with the preset target voltage value in real time. The end face burn-off amount is calculated based on the voltage deviation, and the micro servo drive unit is dynamically driven to perform micron-level physical displacement compensation so that the actual physical size of the dynamic welding gap is kept within the process range. Step S3, Closed-loop upsetting trigger: Monitor the cumulative compensation displacement or heating time. When the preset upsetting conditions are met, instruct the micro servo drive unit to output full-power upsetting thrust to complete the welding.

[0008] A magnetically controlled rotary arc welding equipment, which realizes the above-mentioned magnetically controlled rotary arc welding arc stabilization control method, includes a mechanical actuator and an electrical control system; The mechanical actuator includes a high-rigidity bed. One end of the high-rigidity bed is provided with a fixed clamping unit for clamping a first workpiece to be welded. The other end of the high-rigidity bed is horizontally laid with a precision linear guide rail. A servo follower box for clamping a second workpiece to be welded is slidably connected on the precision linear guide rail. The end faces of the first workpiece to be welded and the second workpiece to be welded are arranged opposite each other, and a dynamic welding gap is formed between the first workpiece to be welded and the second workpiece to be welded. The outer end of the servo follower box is drivenly connected to a micro servo drive unit that provides micron-level linear driving force for the forward and backward movement of the servo follower box. The electrical control system includes: A high-frequency electrical parameter acquisition module is used for high-frequency real-time acquisition of voltage and current fluctuation signals at dynamic welding gaps. High-frequency inverter welding power supply is used to provide basic and transient energy output for welding gaps; The central coordinating controller is electrically connected to the high-frequency electrical parameter acquisition module, the high-frequency inverter welding power supply, and the micro servo drive unit. It is used to execute the above-mentioned magnetic rotary arc welding arc stabilization control method based on the signal fed back by the high-frequency electrical parameter acquisition module.

[0009] In a preferred embodiment of the magnetically controlled rotary arc welding equipment described in this invention, a magnetic field generator is arranged around the periphery of the dynamic welding gap to generate a magnetic field that drives the arc to rotate.

[0010] In a preferred embodiment of the magnetically controlled rotary arc welding equipment described in this invention, the magnetic field generator is configured as a magnetic arc welding head, and the magnetic arc welding head integrates an excitation coil.

[0011] As a preferred embodiment of the magnetically controlled rotary arc welding equipment described in this invention, a cable drag chain is provided on the high-rigidity bed located at the precision linear guide rail to protect the power and signal transmission lines of the servo follower box during frequent movement.

[0012] As a preferred embodiment of the magnetically controlled rotary arc welding equipment described in this invention, the electrical control system further includes a high-precision displacement sensor disposed between the servo follower box and the high-rigidity bed, used to feed back the real-time physical position to the central coordinating controller to calculate the cumulative compensation amount.

[0013] Compared with existing technologies: By using the decoupled independent motion of the servo servo drive unit, the traditional mechanical hard limit is completely replaced. Even if the end face of the first workpiece to be welded has unevenness, the system can compensate for this geometric error through the fast response (micrometer-level advance and retreat) of the micro servo drive unit, ensuring the absolute uniformity of the arc heat input in the entire circumferential direction. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0015] In the figure: 1. First workpiece to be welded; 2. Fixed clamping unit; 3. Magnetic arc welding head; 4. Servo follower box; 5. Precision linear guide; 6. Micro servo drive unit; 7. Cable drag chain; 8. High rigidity bed. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0017] This invention provides a magnetically controlled rotary arc welding equipment; please refer to [link / reference]. Figure 1 This includes mechanical actuators and electrical control systems; The mechanical actuator includes a high-rigidity bed 8, which serves as the basic load-bearing structure of the entire machine. A fixed clamping unit 2 for clamping a first workpiece 1 (such as a long pipe) is fixed on the left side of the high-rigidity bed 8. A precision linear guide 5 is horizontally laid on the right side of the high-rigidity bed 8. A servo follower box 4 for clamping a second workpiece 1 is installed on the precision linear guide 5 through a slider. The end faces of the first workpiece 1 and the second workpiece 1 are arranged opposite each other, and a dynamic welding gap is formed between the first workpiece 1 and the second workpiece 1.

[0018] The right end of the servo follower box 4 is connected to a micro servo drive unit 6 (preferably a combination of a high-precision AC servo motor and a ball screw) that provides micron-level linear driving force for the forward and backward movement of the servo follower box 4. This drive unit can drive the servo follower box 4 to achieve micron-level reciprocating linear motion on the precision linear guide rail 5 by receiving control commands, thereby precisely adjusting the dynamic welding gap between the first workpiece to be welded 1 and the second workpiece to be welded.

[0019] A magnetic field generator is arranged around the periphery of the dynamic welding gap to generate a magnetic field that drives the arc to rotate; the magnetic field generator is a magnetic arc welding head 3, and an excitation coil is integrated inside the magnetic arc welding head 3.

[0020] The high-rigidity bed 8 located at the precision linear guide 5 is equipped with a cable drag chain 7 to protect the power and signal transmission lines of the servo follower box 4 during frequent movement.

[0021] The electrical control system includes: A high-frequency electrical parameter acquisition module is used for high-frequency real-time acquisition of voltage and current fluctuation signals at dynamic welding gaps. High-frequency inverter welding power supply is used to provide basic and transient energy output for welding gaps; The central coordinating controller is electrically connected to the high-frequency electrical parameter acquisition module, the high-frequency inverter welding power supply, and the micro servo drive unit 6. It is used to execute the above-mentioned magnetic rotary arc welding arc stabilization control method based on the signal fed back by the high-frequency electrical parameter acquisition module. A high-precision displacement sensor is installed between the servo follower box 4 and the high-rigidity bed 8 to feed back the real-time physical position to the central coordinating controller in order to calculate the cumulative compensation.

[0022] A method for stabilizing the arc in magnetically controlled rotary arc welding includes the following steps: Step S1, Real-time Perception of Dual-Dimensional Features: First, the micro-servo drive unit 6 drives the servo follower box 4 to move, so that the end faces of the two workpieces reach the preset arc-ignition gap. The magnetic arc welding head 3 is energized to generate a magnetic field, and the high-frequency inverter welding power supply outputs an arc-ignition voltage, igniting the arc in the gap and causing it to rotate at high speed along the end face of the pipe under the action of Lorentz force. After the welding arc is ignited and rotated, the high-frequency electrical parameter acquisition module collects the arc signal (voltage and current signal) at the dynamic welding gap in real time. After signal filtering and feature extraction, the average DC voltage representing the macroscopic arc length and the voltage change rate dU / dt representing the transient fluctuation of the microscopic arc are extracted in parallel.

[0023] Step S2, Spatiotemporal Dual-Dimensional Dynamic Arc Stabilization: During the welding heating stage, the system enters a high-frequency adaptive adjustment mode. Microscopic Energy Transient Intervention: The central coordinating controller monitors the voltage change rate dU / dt in real time. When the sudden change in dU / dt exceeds the set safety threshold, and it is determined that the arc is at risk of instantaneous extinction due to end face burrs or environmental influences, the central coordinating controller immediately issues a transient rescue command to the high-frequency inverter welding power supply without waiting for mechanical displacement adjustment. This command forces the output of a transient surge in breakdown voltage or arc-maintaining current to maintain the microscopic stability of the arc and achieve energy rescue response. By injecting transient high-energy current, "energy rescue" is implemented to suppress arc fluctuations. Macroscopic gap displacement servo: The system monitors the average DC voltage of the welding circuit in real time, and the central coordinating controller compares the average DC voltage with the preset optimal target voltage value in real time. The system calculates the macroscopic burn-off amount of the pipe end face based on the voltage deviation value. As the pipe end face burns, the gap increases, causing the average value to deviate from the target value. At this time, the central coordinating controller continuously sends servo displacement compensation commands to drive the micro servo drive unit 6. The micro servo drive unit 6 drives the servo follower box 4 to perform micron-level physical advance and retreat adjustments, forcing the actual physical size of the dynamic welding gap to always remain within the optimal process range; through real-time closed-loop feedback of voltage and displacement, it dynamically tracks and cancels the arc length drift caused by pipe end face melting and burn-off and uneven processing, ensuring that the physical distance between the end faces is always locked within the optimal range required by the process. Step S3, closed-loop upsetting trigger: The compensation stroke of the micro servo drive unit 6 is recorded in real time. When the cumulative compensation displacement fed back by the high-precision displacement sensor reaches the set end face melting threshold (i.e., melting allowance (proving that the end face has fully reached the plastic state)), or when the set heating time ends, the central coordinating controller shields the arc stabilization logic and instructs the micro servo drive unit 6 to instantly output full-power upsetting thrust. The servo follower box 4 instantly accelerates and advances to close the pipe fitting, forcefully extruding (upsetting) the two end faces to be welded, and completing the final upsetting welding.

[0024] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for stabilizing the arc in magnetically controlled rotary arc welding, characterized in that, Includes the following steps: Step S1, Real-time perception of dual-dimensional features: After the welding arc is started, the voltage and current signals at the dynamic welding gap are collected in real time, and the average DC voltage representing the macro gap state and the voltage change rate dU / dt representing the micro arc transient fluctuation are extracted in parallel. Step S2, Spatiotemporal Dual-Dimensional Dynamic Arc Stabilization: During the welding heating stage, the system enters a high-frequency adaptive adjustment mode. Microscopic energy transient intervention: Real-time monitoring of the voltage change rate dU / dt. When it is determined that the sudden change of dU / dt exceeds the set threshold and there is a risk of arc extinction, the power supply side energy rescue response is immediately triggered, and transient compensation energy is output to maintain the microscopic stability of the arc. Macroscopic gap displacement servo: The average value of the DC voltage is compared with the preset target voltage value in real time. The end face burn-off amount is calculated based on the voltage deviation, and the micro servo drive unit (6) is dynamically driven to perform micron-level physical displacement compensation so that the actual physical size of the dynamic welding gap is kept within the process range. Step S3, state closed-loop upsetting trigger: monitor the cumulative compensation displacement or heating time, and when the preset upsetting conditions are reached, instruct the micro servo drive unit (6) to output full power upsetting thrust to complete the welding.

2. A magnetically controlled rotary arc welding equipment, implementing the magnetically controlled rotary arc welding arc stabilization control method of claim 1, characterized in that, Including mechanical actuators and electrical control systems; The mechanical actuator includes a high-rigidity bed (8), one end of which is provided with a fixed clamping unit (2) for clamping a first workpiece to be welded (1), and the other end of which is horizontally provided with a precision linear guide rail (5). A servo follower box (4) for clamping a second workpiece to be welded is slidably connected on the precision linear guide rail (5). The end faces of the first workpiece to be welded (1) and the second workpiece to be welded are arranged opposite to each other, and a dynamic welding gap is formed between the first workpiece to be welded (1) and the second workpiece to be welded. The outer end of the servo follower box (4) is connected to a micro servo drive unit (6) that provides micron-level linear driving force for the advance and retreat of the servo follower box (4). The electrical control system includes: A high-frequency electrical parameter acquisition module is used for high-frequency real-time acquisition of voltage and current fluctuation signals at dynamic welding gaps. High-frequency inverter welding power supply is used to provide basic and transient energy output for welding gaps; The central coordinating controller is electrically connected to the high-frequency electrical parameter acquisition module, the high-frequency inverter welding power supply and the micro servo drive unit (6), and is used to execute the magnetic control rotary arc welding arc stabilization control method of claim 1 according to the signal fed back by the high-frequency electrical parameter acquisition module.

3. The magnetically controlled rotary arc welding equipment according to claim 2, characterized in that, A magnetic field generator is arranged around the periphery of the dynamic welding gap to generate a magnetic field that drives the electric arc to rotate.

4. The magnetically controlled rotary arc welding equipment according to claim 3, characterized in that, The magnetic field generator is configured as a magnetic arc welding head (3), and the magnetic arc welding head (3) has an integrated excitation coil inside.

5. The magnetically controlled rotary arc welding equipment according to claim 2, characterized in that, The high-rigidity bed (8) located at the precision linear guide (5) is equipped with a cable drag chain (7) to protect the power and signal transmission lines of the servo follower box (4) during frequent movement.

6. The magnetically controlled rotary arc welding equipment according to claim 2, characterized in that, The electrical control system also includes a high-precision displacement sensor located between the servo follower box (4) and the high-rigidity bed (8) to feed back the real-time physical position to the central coordinating controller in order to calculate the cumulative compensation amount.

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