A method for visual-magnetic field low-frame-time synchronous monitoring of micro-plasma arc fuse status

Abstract

A method for low-frame-rate, simultaneous monitoring of the state of micro-plasma arc filaments using a visual-magnetic field approach addresses the high cost and low efficiency of traditional arc additive manufacturing monitoring equipment. Because the timing and extent of metal transition instability during the filament process are uncertain, only full-coverage monitoring is possible, resulting in massive amounts of data and inherent latency. The key technical point of this invention is the coordinated control of the camera's frame rate and the frequency of magnetic field changes to monitor the metal transition state under magnetic field control. By capturing a small number of local area images to identify metal transition patterns, the magnetic field is dynamically adjusted based on these patterns, and the frame rate is changed accordingly. This invention fundamentally reduces the monitoring range, lowers data processing complexity, and improves real-time adjustment, achieving low-cost, high-efficiency monitoring of the micro-plasma arc filament additive manufacturing process.

Description

Technical Field

[0001] This invention specifically relates to a method for visual-magnetic field low-frame synchronous monitoring of the state of micro-plasma arc fuses, which belongs to the field of monitoring of arc fuse additive manufacturing processes in intelligent manufacturing. Background Technology

[0002] In arc additive manufacturing and arc welding, the metal transition state directly affects product quality. Therefore, real-time monitoring of the metal transition state is necessary to adjust process parameters and maintain a stable transition. Monitoring the wire manufacturing process and implementing adaptive process control are important means to improve the stability of the metal transition.

[0003] In the fused wire deposition process, the statically stable metal transition mode is difficult to maintain for extended periods, resulting in poor forming accuracy. To ensure workpiece forming quality, process parameters are typically predicted and planned in advance, or the fused wire process is monitored and readjusted. However, due to the unavoidable "step effect" caused by factors such as thermal accumulation deformation and time-varying process parameters, as well as the deficiencies in current fused wire process monitoring methods, the final forming quality is often unsatisfactory. Therefore, for micro-plasma arc fused wire additive manufacturing, the unstable metal transition during fused wire deposition, leading to internal defects and reduced workpiece contour accuracy, is a bottleneck restricting the development of micro-plasma arc fused wire additive manufacturing technology.

[0004] Currently, the most common and effective monitoring method is to observe the fuse manufacturing process through vision and intelligent image processing. However, this requires high-frame-rate cameras and high-performance image processing chips, as well as high-performance computers and controllers for real-time monitoring and process control. The complexity of the algorithms and the extremely high equipment cost limit the ability of arc fuse additive manufacturing technology to achieve stable manufacturing over long periods. Furthermore, traditional full-coverage passive monitoring generates massive amounts of data and cannot achieve real-time adjustment, hindering the commercialization of arc fuse additive manufacturing technology. Therefore, there is an urgent need to find new methods for monitoring the fluctuating metal transition state to achieve low-cost and efficient monitoring of the micro-plasma arc fuse additive manufacturing process. This is another major challenge facing the development of magnetically controlled fluctuating stable fuse additive manufacturing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a vision-magnetic field frame rate co-control method for monitoring changes in the solid-liquid bonding state during micro-plasma arc filament additive manufacturing. During the filament melting process, the optimal matching between the magnetic field frequency and the visual image frame rate provides timely feedback for subsequent process adjustments and stable metal transition. This invention designs a monitoring method with strong co-control capabilities and a clear principle, simplifying passive monitoring, reducing data processing difficulty, and improving the monitoring efficiency of micro-plasma arc filament additive manufacturing.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] See Figure 1 This method is based on a micro-controlled plasma arc filament manufacturing platform, which includes a wire feeder, a three-dimensional fixture, a metal wire, a micro-plasma gun, a substrate, a magnetron control device, and a camera. The magnetron control device generates a magnetic field in the metal transition region that controls the oscillation of the micro-plasma arc. The micro-plasma gun releases a micro-plasma torch to melt and deposit the metal wire. Before fused deposition modeling, the distance between the filament tip, the center of the plasma torch, and the substrate is adjusted so that the filament feed direction passes through the center below the micro-plasma torch. The magnetic field acts in the metal transition region, controlling the plasma arc to scan in the filament feed direction. The filament feeding device is activated, and the plasma arc contacts the fed filament, melting the filament to produce molten metal. When the plasma arc scans the substrate, it partially melts the substrate in contact with the plasma arc. The partially melted substrate contacts the molten metal produced by the filament melting to form a molten pool. Subsequently, the plasma arc is controlled to perform periodic scans between the filament tip, the molten metal, and the molten pool. Within one metal transition cycle, the camera captures a set of images of the solid-liquid connection state during the micro-plasma arc scanning process. All captured images are divided into groups based on the number of images that are integer multiples of the magnetic field frequency, according to the order of capture time. Within this group, a change in the solid-liquid connection state can be determined, which is the lowest frame rate for the camera to capture. The optimal frame rate is selected to achieve the same low frame rate detection effect between vision and magnetic field, providing timely feedback for subsequent adjustments to the fused deposition modeling process and magnetic field frequency.

[0008] The solid-liquid connection state refers to the connection state between the wire and the molten pool during the material evolution path of the metal wire transitioning from a solid to a liquid state to a molten pool, and then cooling into a solid deposition layer. The metal transition mode classification is based on the spatial position and shape of each substance in the metal transition region image captured by the camera within one cycle. The image processing module can organize and compare the solid-liquid connection state images captured by the camera to classify the current metal transition mode.

[0009] See Figure 2 The metal transition modes within the magnetically controlled micro-plasma arc scanning cycle are divided into (a) a wave-liquid bridge transition mode with continuous solid-liquid connection, (b) a wave-contact transition mode with intermittent solid-liquid connection, and (c) a wave-chaotic mode with no solid-liquid contact.

[0010] The theoretical principle of the visual-magnetic field low-frame-rate synchronous monitoring mechanism is as follows: During the micro-plasma arc filament additive manufacturing process, active visual monitoring of the metal transition process is performed within one cycle of the magnetic field-controlled micro-plasma arc scanning. Utilizing the periodicity of the fluctuating metal transition, all captured images are grouped according to the shooting time sequence, with the number of images being an integer multiple of the magnetic field frequency (starting from 1). If a change in the solid-liquid connection state can be determined in a group of images, the number of images in that group is the minimum frame rate at which the transition mode change can be observed. If it cannot be determined, the multiple is increased by one until the optimal frame rate that meets the shooting requirements is obtained. If the magnetic field frequency changes, the camera frame rate is adjusted in real time according to the linkage relationship to obtain the optimal frame rate of the camera at this time. In this way, the visual-magnetic field low-frame-rate synchronous monitoring linkage mechanism is constructed to capture contour images of the metal transition area. The image processing module divides the metal transition mode according to the solid-liquid connection state in the captured contour images, and judges whether the metal transition is stable based on the metal transition mode. Then, the filament process parameters and magnetic field frequency are adjusted to promote the stability of the micro-plasma arc filament state. The above steps are repeated until the filament process ends.

[0011] The main feature of this invention is that there is a correlation between the camera's shooting frame rate and the frequency of the applied magnetic field used to monitor the fused wire additive manufacturing process. During the manufacturing process, the camera's shooting frame rate and the frequency of magnetic field changes are jointly controlled to monitor the metal transition state under magnetic field control. The metal transition pattern is identified by shooting a small number of local area images, and the magnetic field is dynamically adjusted and the shooting frame rate is changed accordingly based on the metal transition pattern.

[0012] See Figure 3 The beneficial effects of this invention are that it provides a method for visual-magnetic field low-frame-rate synchronous monitoring of the solid-liquid bonding state in micro-plasma arc filament additive manufacturing. Utilizing the fluctuating regularity of the metal transition state, it proposes an active monitoring method that determines the shooting frame rate based on the magnetic field frequency. This requires only the collection and processing of a small amount of image data, significantly reducing the computational load. It only requires a common low-frame-rate camera, reducing the cost of purchasing high-frame-rate cameras. Process adjustments and fluctuation transition mode changes are performed synchronously within the fluctuation cycle, fundamentally reducing the monitoring range, lowering data processing difficulty, and avoiding post-processing adjustments. Attached Figure Description

[0013] Figure 1 A monitoring platform for manufacturing magnetically controlled micro-plasma arc fuses.

[0014] Figure 2 This is a schematic diagram of the connection between the wire and the molten pool during the scanning cycle of a magnetron micro-plasma arc.

[0015] Figure 3 This is a comparison chart of methods for monitoring the fuse process.

[0016] Figure 4To implement the flowchart. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0018] See Figure 1 , Figure 4 This method is based on a micro-controlled plasma arc filament fabrication platform, which includes a wire feeder, a three-dimensional fixture, a metal wire, a micro-plasma gun, a substrate, a magnetron control device, and a camera. The magnetron control device generates a magnetic field that regulates the filament melting process, while the micro-plasma gun generates a micro-plasma torch to melt and deposit the metal wire. Before filament fabrication begins, the relative position of the wire and the molten pool is adjusted so that the wire head is directly below the micro-plasma gun. The power is then turned on to start the equipment. The micro-plasma gun generates a micro-plasma arc that periodically scans between the wire and the molten pool, providing a stable heat source for the filament melting process. The magnetron control device generates a magnetic field in the metal transition region to regulate the oscillation of the micro-plasma arc. The visual-magnetic field low-frequency frame-matching mechanism groups all captured images according to the shooting time sequence, with each image number being an integer multiple of the magnetic field frequency (starting from 1). If a change in the solid-liquid bonding state can be determined in a group of images, the number of images in that group is the lowest frame rate captured by the camera capable of observing the transition mode change. If the frame rate cannot be determined, the multiplier is increased by one until the optimal frame rate that meets the shooting requirements is obtained to capture the outline image of the metal transition area. The image is processed by the image processing module and the current metal transition mode is divided into (a) the undulating liquid bridge transition mode with continuous solid-liquid connection, (b) the undulating contact transition mode with intermittent solid-liquid connection, and (c) the undulating chaotic mode with no solid-liquid contact. Then, it is determined whether the metal transition state is stable. If it is unstable, the frequency of the magnetic field generated by the metal fuse process and the magnetocontrol device is adjusted. The camera frame rate is adjusted in real time with the change of magnetic field frequency. Otherwise, the fuse is manufactured according to the current parameters, and the above monitoring steps are repeated until the fuse manufacturing is completed.

[0019] Case Study 1 illustrates a monitoring method for repairing deposited layers in fused-wire additive manufacturing. An automated fused-wire additive manufacturing system, comprised of a drive motor, gyroscope, encoder, and other peripherals, performs real-time repair of the deposited layer. Simultaneously, a magnetic field perpendicular to the wire feed direction is generated in the metal transition region. A camera positioned beside the deposited layer is adjusted via a sliding rail and lifting mechanism to better observe the movement of the automated system and the repair process in real time. A low-frame-rate synchronization mechanism between the magnetic field and camera is established to synchronously record cross-sectional data of the deposited layer and feed it back to the image processing system. The image processing system, after organizing, processing, and analyzing the image data, feeds the parameters back to the main control system. Upon receiving the data, the main control system controls the automated fused-wire additive manufacturing system to adjust the repair parameters in real time, creating a positive feedback loop. To reduce errors during the repair process, changes in the magnetic field frequency trigger synchronous adjustments to the camera frame rate, repeating the above steps.

[0020] Implementation Case 2: A monitoring method used in micro-plasma arc additive manufacturing of micro-parts. See [link / reference]. Figure 1 During the micro-plasma arc molten wire transition process, the magnetron sputtering device applies a local magnetic field that can adjust the oscillation of the micro-plasma arc in the metal transition area. A low-frame-frequency co-frequency mechanism between the magnetic field and the camera is established to record the solid-liquid connection state of the wire and the molten pool in real time and feed it back to the image processing system. The image processing module organizes and classifies the current metal transition mode. If it is stable, the molten wire is manufactured according to the existing parameters. Otherwise, the metal transition state is stabilized by changing the magnetic field strength and frequency to control the shape, direction and dwell time of the micro-plasma arc. At the same time, the camera frame rate is adjusted in real time with the change of magnetic field frequency and image data is generated to determine whether the current metal transition state is stable. The dynamic stability of the metal transition process is maintained and the above steps are repeated until the micro-part is manufactured.

Claims

1. A method for visual-magnetic field low-frame-time synchronous monitoring of the state of a micro-plasma arc fuse, characterized in that: By leveraging the periodicity of wave-like metal transitions, a low-frame-frequency co-control relationship is established between the image capture frame rate required for judging metal transition mode changes and the magnetic field frequency. Images are grouped according to the number of images that are integer multiples of the magnetic field frequency. All captured images are grouped in chronological order of capture time. If a change in the solid-liquid connection state can be determined in a group of images, the number of images in that group is the minimum frame rate that the camera can capture to observe the transition mode change. If it cannot be determined, the multiple is increased by one until the optimal frame rate that meets the shooting requirements is obtained. If the magnetic field frequency changes, the camera frame rate is adjusted in real time according to the co-control relationship to obtain the optimal frame rate of the camera at that time. This constructs a vision-magnetic field low-frame-frequency co-control mechanism.

2. The method for visual-magnetic field low-frame synchronous monitoring of micro-plasma arc fuse status according to claim 1, characterized in that: in In the micro-plasma arc filament additive manufacturing process, the metal transition process is actively monitored visually within one cycle of the magnetic field-controlled micro-plasma arc scanning. A camera captures the outline image of the metal transition area at the optimal frame rate. The image processing module classifies the metal transition mode based on the solid-liquid connection state in the captured outline image. Based on the metal transition mode, it determines whether the metal transition is stable and then adjusts the filament process parameters and magnetic field frequency to promote the stability of the micro-plasma arc filament.

3. The method for visual-magnetic field low-frame synchronous monitoring of micro-plasma arc fuse status according to claim 1 or 2, characterized in that: The solid-liquid connection state refers to the connection state between the wire and the molten pool in the material evolution path of the metal wire from solid to liquid to molten pool, and the molten pool cooling into a solid deposition layer.

4. The method for visual-magnetic field low-frame-time synchronous monitoring of micro-plasma arc fuse status according to claim 2, characterized in that: The metal transition region includes the area space scanned by the micro-plasma arc controlled energy, part of the filament, molten metal, molten pool and substrate; the metal transition mode division is based on the spatial position and shape of each substance in the metal transition region image captured by the camera in one cycle.

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