Arc Interference Research Articles

A lightweight efficient semantic segmentation with encoder-decoder for arc interference in robotic arc welding

Recognizing laser stripes under conditions of arc interference is a persistent challenge faced by linear structured light sensors due to their similarity with noise in morphological characteristics. In this paper, a symmetrical encoder-decoder semantic segmentation model named LSRNet (lightweight stripe recognition network) is proposed that enables real-time detection of laser stripes in environments with strong arc interference. It analyzes the difference between arc and laser stripe from the semantic point of view. Firstly, to facilitate quick and accurate recognition of laser stripes, we designed a Depthwise-separable Factorized Module that is both efficient and scalable with a larger receptive field. Moreover, due to the difficulty in distinguishing laser stripes from arcs in a local context, a Multi-scale Depthwise-separable Factorized Module is designed to capture more context information. Secondly, the Unified Attention Fusion Module is used to enhance the feature representation of the laser stripe. Additionally, The combination of DiceLoss(dice coefficient loss) and CELoss(cross-entropy loss) is introduced to optimize the loss, which addresses the pixel imbalance challenge that the pixels of the laser stripe are much less than the background pixels. Finally, based on the images collected in the industrial field, our ArcDataset is created for model training. Experimental results show that the proposed method achieves the highest intersection over union of 88.0% in laser stripe segmentation and a recognition speed of 101.3 FPS(frames per second).

Development of seam tracking device in asynchronous tandem welding with arc sensing

Tandem welding is extensively used for welding large structures, such as ships and plants, for increased welding speed and volume. Seam tracking is essential because of a large amount of thermal deformation. However, in tandem welding, arc interference causes current and voltage to vary non-uniformly, leading to difficulties in seam tracking. Therefore, in this study, an optimal signal was identified for seam tracking in tandem welding and evaluated. To select the seam-tracking signal, an algorithm was developed that separates the welding signal into peak, average, and base. Based on the collected data, regression and signal-to-noise ratio analyses were performed to identify a suitable seam-tracking signal. To trace the welding line based on the selected signal, the welding signal was checked by weaving on the V-groove specimen. As a result, the current area difference of the welding signal generated between the left and right parts of the center of the V-groove could be calculated. An algorithm and equipment for seam tracking were constructed using the area difference of the welding current. Finally, the seam tracking system was verified by conducting an actual test using the equipment to which the algorithm was applied.

Effect of phase shift on arc interference and weld bead formation in aluminum alloy tandem GMAW with a median pulsed waveform

Effect of phase shift on arc interference and weld bead formation in aluminum alloy tandem GMAW with a median pulsed waveform

Effect of high-frequency phase shift on metal transfer and weld formation in aluminum alloy double-wire DP-GMAW

This paper presents a double-wire gas metal arc welding (GMAW) system for investigating the effects of high-frequency phase shift of the double pulse on metal transfer and bead formation. First, a theoretical analysis of the double-wire metal transfer process was carried out and a mathematical model of droplet impact was established. The metal transfer processes of different phase shifts were then photographed using a high-speed camera, the droplet velocity and impact on the weld pool at different phase shifts were calculated, and geometries of the weld beads were analyzed. Penetration of the longitudinal section fluctuated due to the modulated double pulse and the penetration depth increased with increasing phase shift; however, the weld reinforcement was irregular. The weld width increased with decreasing phase shift due to the temperature gradient. Moreover, since a reduction in double arc interference reduced the size and number of pores, porosity of the weld decreased with higher phase shifts. Stirring induced by the double pulse promoted floating and precipitation of pores. The experimental results show that a 180° phase shift leads to the most stable welding process resulting in a sound weld and an obvious fish-scale appearance. No undercut, hump, or spatter defects were observed. In addition, the deepest penetration with a uniform and smooth penetration fluctuation curve and the lowest porosity were also achieved with a phase shift of 180°.

Dimension Precision and Uniformability Depending on the Interpass Distance Variation of Automated-Wire Arc Additive Manufacturing using 5 Cr-4 Mo Tool Steel Alloy

Die casting molds for aluminum are fabricated using machining billets of tool steels, such as Cr-Mo tool steel. However, this approach has several limitations, including significant material loss and a long lead time. Wire arc additive manufacturing (WAAM) is an alternative fabrication method that yields low material loss and has a short lead time. However, WAAM involves the repetitive stacking of layers based on designed tool paths using CAD/CAM. Thus, the predictability and uniformability of each layer are the most important factors. The interpass distance is an important parameter in a given process; however, studies on the interpass distance of the WAAM process are limited. In this study, it was determined that the interpass distance significantly influences the arc stability owing to the arc interference induced by the variation in distance from the prior deposited pass; more arc interference was observed as the interpass distance decreased. This phenomenon was validated via analysis using a high-speed camera and the variation in the amount of spatter. Furthermore, it was observed that the interpass distance influences the dimensional precision and uniformability. The interpass distance influences the arc interference unless it is greater than 100%. Thus, it is important to determine a point of balance based on the arc stability, dimension predictability, and uniformability of each layer.

Evaluation of Arc Stability in Double-Wire DP-GMAW of Aluminum Alloy Based on U-I Graph

Abstract Severe arc interference in double-wire double pulsed gas metal arc welding (DP-GMAW) can affect the stability of the welding process. In this study, voltage and current waveforms during double-wire DP-GMAW of aluminum (Al) alloy in the 0 deg and 180 deg phase shift modes were recorded. The relationship between arc voltage and welding current was investigated through the output voltage-current (U-I) graph. In addition, arc load characteristics and variation of voltage and current during the DP switching process were analyzed. The arc behavior was recorded throughout the welding process using a high-speed photography system, and the relationship between the U-I graph characteristics and arc stability was further investigated. The experimental results demonstrate that the arc is more stable in the 180 deg phase shift mode. In both phases, the leading arc impedance is more capacitive, and the trailing arc impedance is more resistive.

Analisis Karakteristik Busur Api Listrik Pada Tegangan Rendah Arus Searah (DC) Dipengaruhi Oleh Resistansi Konduktor

Arc faults are a fire-safety risk in both AC (alternating current) and DC wiring, but reliable detection of arc faults and determining the appropriate response is particularly difficult in DC plug-load circuits. This study will discuss the impact of impedance on arc interference characteristics in DC low voltage systems. Experiments were conducted involving accidents that increasingly occur using the arc chamber as a means of experimenting with independent variables including cable cross-sectional area and the number of fibers and control variables will consist of currents and voltages using devices using a Picoscope. In the analysis obtained values of the conductor resistance affect the characteristics of electric arcs. The smaller the value of the conductor resistance, the greater the value of the arc current produced. This is consistent with the values obtained from the study, when the smallest conductor resistance of 0.036 Ω obtained the highest value at the current value and electric arc power of 20.57 A and 19.43 W at the cross section of the conductor 1.5 mm2 with 24 fibers.

Three-Dimensional Reconstruction of Welding Pool Surface by Binocular Vision

Current research of binocular vision systems mainly need to resolve the camera’s intrinsic parameters before the reconstruction of three-dimensional (3D) objects. The classical Zhang’ calibration is hardly to calculate all errors caused by perspective distortion and lens distortion. Also, the image-matching algorithm of the binocular vision system still needs to be improved to accelerate the reconstruction speed of welding pool surfaces. In this paper, a preset coordinate system was utilized for camera calibration instead of Zhang’ calibration. The binocular vision system was modified to capture images of welding pool surfaces by suppressing the strong arc interference during gas metal arc welding. Combining and improving the algorithms of speeded up robust features, binary robust invariant scalable keypoints, and KAZE, the feature information of points (i.e., RGB values, pixel coordinates) was extracted as the feature vector of the welding pool surface. Based on the characteristics of the welding images, a mismatch-elimination algorithm was developed to increase the accuracy of image-matching algorithms. The world coordinates of matching feature points were calculated to reconstruct the 3D shape of the welding pool surface. The effectiveness and accuracy of the reconstruction of welding pool surfaces were verified by experimental results. This research proposes the development of binocular vision algorithms that can reconstruct the surface of welding pools accurately to realize intelligent welding control systems in the future.

The effect of a hot-wire in the tandem GMAW process ascertained by developing a multiphysics simulation model

Physical phenomena such as arc interference, deflection in droplet transfer, and bulging in weld pool are observed in the tandem gas metal arc welding (GMAW) process. A hot-wire with opposite polarities to the leading and trailing electrodes was introduced to counter these phenomena. The effects of the hot-wire were assessed experimentally. A 3D steady-state numerical analysis model was used to calculate the temperatures and the shapes of the leading and trailing arcs, respectively, as well as the arc flows and the electromagnetic forces. The results of our experiments and our numerical analyses clarify the effects of a decrease in the electromagnetic force around tandem electrodes due to the hot-wire. This decrease mitigates arc interference and the deflection in droplet transfer. Furthermore, it plays a role in reducing the height of the bulge generated on the surface of the weld pool. These effects can prevent defects in tandem GMAW processes.

Molten image fusion and enhancement based on image decomposition in frequency domain

In this paper, we propose a novel molten image enhancement and fusion method based on image decomposition in frequency domain. The algorithm combines the guided filter to maintain the original edge and details and to make it show a more permeable visual effect. Firstly, the high-quality molten imaging band is obtained by analyzing the characteristic spectra of welding materials and arcs. We choose the bands with more spectra feature of materials and weaker arc interference as our optical path channels and collect color images at the same moment to obtain more molten information. Then, after a series of image preprocessing, we combine the details extraction strategy and the guided filter together to yield a novel fusion algorithm, which can make the fusion result to have rich information, clearer edge and higher contrast. Finally, the experimental results show that the proposed method has obvious advantages over some existing methods from the objective and the subjective view.

Discrete wavelet analysis of mutually interfering co-existing welding signals in twin-wire robotic welding

The article presents new findings on arc stability in twin-wire robotic arc welding corresponding to the torch orientation and electrodes' position. The two mutually influencing co-existing arcs affect the stability of counterpart arc, and thereby alter the weld bead properties. The complex interaction between the arcs is determined by multi-resolution time-frequency spectrum using wavelet analysis. The wavelet-energy-entropy of the signals are analyzed to quantify the arc stability. Several experiments are conducted with different combinations of welding currents at primary and secondary electrodes (vis-a-vis one who initiates and follows the arching sequence, respectively) in tandem and transverse orientation of the torch. The investigation divulges that electrode positions and torch orientation significantly impact arc stability which in turn impacts the heat input and weld bead geometry. The arc penetration in tandem orientation is augmented by the secondary arc that operates in the same weld pool. While the transverse orientation improves the arc stability and facilitates a wider weld bead with reasonable weld penetration suitable for applications such as wire additive manufacturing and cladding. An approach for predicting arc stability as a function of process parameters is a significant contribution from this investigation. The insight into the arching phenomenon in twin-wire gas metal arc welding due to the investigation is expected to help the machine builders to design an appropriate controller that minimizes arc interference.

Penetration Estimation of GMA Backing Welding Based on Weld Pool Geometry Parameters

Penetration estimation is a prerequisite of the automation of backing welding based on vision sensing technology. However, the arc interference in welding process leads to the difficulties of extracting the weld pool characteristic information, which brings great challenges to the penetration estimation. At present, most researches focus on the extraction of weld pool geometry parameters, and the visual sensing systems are complex in structure and complicated in the image processing algorithms. The research of penetration estimation based on weld pool geometry parameters is still in the exploratory stage. The purpose of this paper is to research the relationship between the weld pool geometry parameters and the penetration during backing welding and to estimate penetration using the weld pool geometry parameters. A passive vision sensing test system for gas metal arc (GMA) backing welding was established. An image processing algorithm was developed to extract the weld pool geometry parameters, namely, the area, maximum width and length, half-length, length-width ratio and advancing contact angle (simplified as AWP, MWWP, MLWP, HLWP, LWR and ACA, respectively). The corresponding relationships between the weld pool geometry parameters and the penetration state were explored by analysing their changes with the welding current and speed. The distribution of the weld pool geometry parameters corresponding to penetration was determined. When the AWP of the weld pool is within a certain range and the values of LWR and ACA are close to their maximum and minimum respectively, the penetration is in good condition. A mathematical model with the weld pool geometry parameters as independent variables and the back-bead width (the indicator of the penetration state) as a dependent variable was established based on multivariable linear regression analysis, and relevant statistical tests were carried out. Multivariable linear regression equations for the weld pool geometry parameters and the back-bead width were deduced according to the variations in the current and speed, and the equations can be used to estimate the penetration of backing welding. The study provides a solution to penetration estimation of GMA backing welding based on automatic vision sensing.

Effects of pulse phase difference on metal transfer process and weld formation in the integrated circular triple-electrode GMAW

The pulse synergic control on three arcs in the integrated circular triple-electrode GMAW was proposed to reduce arc interference. The research focused on the effects of pulse phase difference on metal transfer process and weld formation. In the aspect of metal transfer mode, it was found that one droplet per pulse accounted for a higher proportion at pulse phase difference of 120°, followed by pulse phase difference of 180°. However, complete one droplet per pulse hardly occurred at pulse phase difference of 0°, and short-circuiting transfer and one droplet multiple pulses became main transfer mode. In the aspect of weld formation, there were no distinct differences among weld widths and weld reinforcements under three pulse phase differences of 0°, 120°, and 180°. Nevertheless, the weld depths under three pulse phase differences successively varied from minimum to maximum. Moreover, the special cross-section appearance of “twin peaks” was formed at pulse phase difference of 120°. There were two main reasons for this phenomenon, i.e., arc force and droplet impact.

Double arc interference and dynamic behavior characteristics of double wire double-pulsed GMAW

The double wire gas metal arc welding (GMAW) technology combined with double pulse low-frequency modulation offers the benefits of the higher efficiency of double wire GMAW combined with superior weld joint quality offered by double pulse low-frequency modulation. However, the potential for severe double arc interference of double wire double-pulsed GMAW affects the stability of the welding process and has thus far limited its widespread use. In this study, high-speed photography was used to record the arc profiles and arc interference of double wire double-pulsed GMAW in the synchronous and alternant phases, while the voltage and current waveforms were simultaneously recorded. Experimental results demonstrated that the double arc deflection of the strong pulse was more severe than that of the weak pulse due to the high current associated with a strong pulse. It was also discovered that the trailing arc stiffness was lower than the leading arc stiffness. Moreover, the deflection of trailing arc was greater under the influence of the leading arc’s electromagnetic attraction. Whereas, the arc deflection of the pulse stage in the alternant phase was small, less than that of the pulse stage in the synchronous phase, the arc deflection of the background stage was much greater. Furthermore, the arc deflections of the pulse and background stages in the synchronous phase were smaller than the arc deflection of the background stage in the alternant phase. Finally, the leading and in the synchronous phase maintained their stiffness and demonstrated weaker magnetic arc blow, fewer spatters, a more refined fish-scale appearance, and weld beads with better uniformity.

An improved simulation model for three-wire gas metal arc welding

A three-dimensional numerical model was established to improve the accuracy of simulation with stationary three-wire GMAW method. High-speed photography was utilized to detect the details of welding process. The effective radius for arcs was calculated by Abel inversion method. Besides, due to arc interference, transverse velocities of droplets were added by a theoretical calculation method. The simulated longitudinal cross-sectional welded shape indicated good corresponding to the optical result. Moreover, the flow pattern of simulated results accorded well with the reality. According to the simulation, there existed upward mobility in the leading and trailing pools which can be attributed to the droplet impact. This mobility can cause the accumulation of molten metal at the side near middle pool. Therefore, it will accelerate the process to form common weld pool.

Research on arc interference and welding operating point change of twin wire MIG welding

In order to improve the understanding on arc interference behavior and verify the welding operating point change during twin wire MIG welding, the synchronous acquisition system has been established to acquire instantaneous information of electric signals, arc profile, and droplet transfer including dynamic arc length variation. It showed that the current and voltage signals changed significantly after trailing arc (T-arc) was added to the leading arc (L-arc) in a stable welding process. Moreover, the arc agitation of L-arc increased with increasing the current of T-arc but decreased with increasing the inter-wire distance. The results also showed that the stable spray transfer of L-arc was destroyed and deflected due to the effect of T-arc. With respect to a single wire welding, the arc length of L-arc increased and the welding operating point changed during the twin wire welding.

The dynamic behavior of double arc interference in high-power double wire pulsed GMAW

High-power double wire pulsed gas metal arc welding (GMAW) exhibits higher welding efficiency than traditional double wire pulsed GMAW. However, severe interference caused by the high-power double arc impairs welding stability. Based on the analysis of the double arc interference forming principle, two phase modes were examined in this study: the alternating phase mode and the synchronous phase mode. In both phase modes, the welding arc voltage and current were recorded, and double arc profiles were also achieved using the high-speed photographic system. Comparison of the experimental results showed that in high-power welding, the electric arc processes produced superior arc stiffness in synchronous phase mode compared to the alternating phase mode, and the magnetic blow was alleviated. Therefore, it can be concluded that the double arc interference in the alternating phase mode was more severe, while the double arc interference in the synchronous phase mode was significantly reduced.

Analysis of arc interference and welding stability in twin wire GMA welding

In order to better understand the arc interference behavior and welding stability in twin wire GMA welding, the synchronous acquisition system has been established to acquire instantaneous information of electric signals, arc profile, and droplet transfer including dynamic arc length variation. The results showed that after Trailing arc (T-arc) was added to the Leading arc (L-arc) in a stable welding process, the current of L-arc decreased and the voltage kept constant. The stable globular transfer of L-arc was destroyed and deflected, turned into spray transfer due to the effect of T-arc. Compared to the single wire welding, the arc length of L-arc increased and the welding operating point changed in twin wire welding.

Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc) is added to the middle arc (M-arc) in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

Study on Arc Stability Mechanism in High-Speed Tandem GMA Welding

Tandem GMA welding technology has high deposition rates and good welding quality. But the electromagnetic interference (EMI) between the tandem GMA welding arcs is the most important factor which can influence the welding quality .Via Orthogonal Experiments and variance analysis, this paper did some basic theory research of the mutual arc interference mechanism in the GMA welding. The study was carried out from three mainly aspects ,the welding arc length control mode ,the parameters of the control pulse and the optimal range parameters in high-speed welding .The high-speed camera system was used to observe the metal transfer .In this paper the researchers realized the stability work of high-speed movement of tandem GMAW welding .