Bypass Coupling Research Articles

Continuous contact transfer behavior in bypass coupling triple-wire indirect arc welding

Continuous contact transfer behavior in bypass coupling triple-wire indirect arc welding

Experimental and Numerical Investigation of the Thermal and Force Regulation Mechanism of Bypass Coupling Double-Sided Arc Welding Based on 6061 Aluminum Alloy

In this study, 6061 aluminum alloy was proposed for welding using bypass coupling double-sided arc welding (BCO-DASW) to further improve its welding quality and efficiency. To gain insight into the thermal and force regulation mechanism of the BCO-DASW of 6061 aluminum alloy, the dynamic effects of the high-temperature plasma inside the arc with various parameters were fully compared and investigated through the combined method of the physical experiment and the numerical simulation. The thermal flow field of the hybrid arc was analyzed numerically. Furthermore, its working adaptability and mechanical behaviors were studied experimentally. The results show that a single penetration of the 6 mm sheets can be achieved without visible defects when the center offset of the arcs is within 3 mm on both sides of the base metal during BCO-DASW. Through the thermal analysis, it was found that, compared with the MIG process, the introduction of the bypass arc lead to a temperature decrease at the bottom of the hybrid arc due to energy redistribution. Furthermore, through the kinetic analysis, it was found that not only could the level of arc pressure be reduced, but also the action range of the arc pressure could be regulated up to 4.6 mm. The thermal force regulation mechanism worked together to enhance the stability of the molten pool and achieves good joint strength during the BCO-DASW of 6061 aluminum alloy. This research not only has great significance in further improving the welding quality and efficiency of aluminum alloy, but also deeper understanding of the energy regulation mechanism during aluminum alloy welding.

Optimization of welding parameters for BCTW-GIA single-pass welding using RSM

ABSTRACTBypass coupling triple-wire indirect arc (BCTW-GIA) welding technology was applied to single-pass welding for medium and thick plates. The regression models between process variables and target responses were built with response surface methodology (RSM) based on central composite design (CCD). The effect of significant process variables namely bypass current, groove gap, plate thickness, and welding speed on penetration-to-width ratio (P/W) of weld joint and tensile strength (TS) was evaluated. Guiding process parameters were determined with numerical optimization for BCTW-GIA single-pass welding of 8 mm, 10 mm, and 12 mm thickness steel plates. With the advice parameters, the average tensile strength of the weldments with three thickness were 558 MPa, 539 MPa, and 547 MPa. The true P/W of butt joints was also in desirable range. That the error between predicated value and experiment value was no more than 10% emphasized the positive effect of regression model of TS and P/W.

Investigation of arc behavior and droplet transfer in bypass coupling triple-wire indirect arc welding

Investigation of arc behavior and droplet transfer in bypass coupling triple-wire indirect arc welding

A novel modification to TW-GIA for controlling heat input of base metal

ABSTRACT Bypass coupling triple-wire gas indirect arc welding (TW-GIA) has been proposed to control the heat input of base metal and consequently improve the weld forming as per the requirement. The influence of the bypass current on arc behavior, welding stability, and weld forming have been investigated. Results showed that the wetting angle and reinforcement reduced gradually, and the weld bead penetration increased with the bypass current increase. The reason was that the workpiece heating mode was changed due to the bypass circuit coupling. It was observed that the heat source was composed of two indirect arcs and two direct arcs, and they were in a coupling state. When the bypass current was 280 A, the electrical parameters of arc fluctuations were at a maximum, and the coupled arc state was not conducive to obtain a stable welding process. Compared to the lack of sidewall fusion and incomplete joint penetration defects of the weld with TW-GIA, the good butt joint of 12 mm thickness steel plates was successfully obtained with bypass coupling TW-GIA under the same energy consumption.

Numerical Analysis of Physical Characteristics and Heat Transfer Decoupling Behavior in Bypass Coupling Variable Polarity Plasma Arc.

A novel bypass coupling variable polarity plasma arc was proposed to achieve the accurate adjusting of heat and mass transfer in the welding and additive manufacturing of aluminum alloy. However, the physical characteristics and decoupled transfer behavior remain unclear, restricting its application and development. A three-dimensional model of the bypass coupling variable polarity plasma arc was built based on Kirchhoff’s law, the main arc and the bypass arc are coupled by an electromagnetic field. The model of current attachment on the tungsten electrode surface is included for simulating different heating processes of the EP and EN phases in the coupling arc. The distribution of temperature field, flow field, and current density of the bypass coupling variable polarity plasma arc was studied by the three-dimensional numerical model. The heat input on the base metal under different current conditions is quantified. To verify the model, the arc voltages are compared and the results in simulation and experiment agree with each other well. The results show that the radius of the bypass coupling arc with or without bypass current action on the base metal is different, and the flow vector of the bypass coupling arc plasma with bypass current is larger than the arc without bypass current. By comparing the heat transfer on the electrodes’ boundary under different current conditions, it is found that increasing the bypass current results in the rise in heat input on the base metal. Therefore, it is concluded that using bypass current is unable to completely decouple the wire melting and the heat input of the base metal. The decoupled degree of heat transfer is one of the important factors for accurate control in the manufacturing process with this coupling arc.

Microstructure and corrosion resistance of stainless steel produced by bypass coupling twin-wire indirect arc additive manufacturing

Microstructure and corrosion resistance of stainless steel produced by bypass coupling twin-wire indirect arc additive manufacturing

Simulation and control of metal droplet transfer in bypass coupling wire arc additive manufacturing

The influences of bypass current and wire feed speed are utilized to change the metal droplet transfer mode for bypass coupling wire-arcing additive manufacturing (BC-WAAW). To fully understand the influence of experimental factors on the wire melting process, this study establishes a mathematical model for the wire melting process, and several simulation experiments are carried out to prove the effectiveness of this mathematical model. The influence of changing the filler wire process on the stability of the wire melting process is simulated. A negative feedback control method with a single input and single output is proposed, which can control the stability of the wire melting process. The results show that the established mathematical model can well reflect the wire melting process in bypass coupling arcing additive manufacturing. The wire feed speed has a strong influence on the wire extension. The negative feedback control method can realize real-time control of filler wire process stability. The deposition process is more stable in the arcing additive manufacturing process, and the forming accuracy of a single multilayer deposition wall is further improved.

Characteristics of bypass coupling twin-wire indirect arc welding with high-speed welding mode

The welding characteristics in the process of bypass coupling twin-wire indirect arc welding (BC-TWIAW) with high-speed welding mode was comprehensively investigated. Under the condition of the total current of 300 A, the direct arc and indirect arc mainly periodically burned alternately. Its alternating frequency increased with cathode wire feeding speed increase. Nevertheless, it is also found that these two arc burned simultaneously for a very short duration. The indirect arc between the twin wires was principally used for melting the wire while the direct arc was beneficial for deepening the molten pool. Overall, the alternating burning of two arcs could remarkably reduce the heat input into the workpiece. Irrespective of the cathode wire feeding speed, the arc voltage and total welding current generally remained stable. Meanwhile, the droplet transfer patterns changed periodically accompanying with the alternative burning between the two arcs. The droplets of cathode wire mainly transferred into the molten pool globularly. When the cathode wire feeding speed was slow, the droplets of anode wire was mainly in stable spray transfer mode. The anode wire droplet successively experienced spray transfer, short circuiting transfer and globular transfer in turn with the acceleration of cathode wire feeding. Even though the deposition efficiency was improved with a faster cathode wire feeding speed, too fast feeding speed might lead to frequent short circuit explosion and impair the weld formation. Considering both the deposition efficiency and weld formation, the feeding speed of cathode wire should be adjusted at 40%–50% of the anode wire.

Effect of bypass coupling current on corrosion resistance of twin-wire indirect arc surfacing layer

Corrosion resistance of stainless steel surfacing layer prepared by twin-wire indirect arc welding (TWIAW) under different bypass coupling current was studied. For bypass coupling TWIAW(BC-TWIAW), the welding arc was a hybrid arc consisting of indirect arc and direct arc burning alternately. Increased cathode wire feeding speed raised current of indirect arc, which was beneficial for promoting wire melting and adjusting solidification rate. With a higher cathode wire feeding speed, weld solidified faster, and the corrosion resistance was significantly improved. Passive film of BC-TWIAW layers owned the characteristics of bipolar semiconductors with less charge carriers.

Cladding Inconel 625 on cast iron via bypass coupling micro-plasma arc welding

There is great interest to deposit a layer of Inconel 625 nickel-base super-alloy on the surface of metallic substrate to increase the corrosion resistance for the services in harsh environment. In this work, we use the bypass-coupled micro-plasma arc welding to form a layer of Inconel 625 on the plate of QT-400 nodular cast iron and study the effect of the bypass current on the topology of the Inconel 625 layer. There exists spatial distribution of dendrites in the cladding layer along the direction normal to the bonding interface between the cladding layer and the plate of QT-400 nodular cast iron. The fusion zone near the interface between the cladding layer and the plate of QT-400 nodular cast iron has the largest Vickers hardness of 630 HV.

Stopband Singlet: A Novel Structure Implementing Resonating Couplings

In this letter a new type of singlet is introduced, called stopband singlet . The new singlet is implemented in rectangular waveguide, exploiting TE301 as resonating mode and TE10 mode as nonresonating bypass coupling. Unlike the previously introduced singlets [which produce one transmission zero (TZ) and one reflection zero (RZ)], the stopband singlet generates one TZ alone (the RZ is pushed to infinity). The novel structure allows designing filters with resonating couplings introducing TZs very close to the passband (difficult to implement with other resonating waveguide discontinuities). A prototype two-pole filter with one TZ has been designed and fabricated to validate experimentally the novel singlet configuration.

SIW bandpass filters in modified box‐section scheme with bypass/constant/frequency‐dependent coupling in diagonal cross‐coupling path

Here, three fourth-order bandpass filters (BPFs) in modified box-section schemes using substrate integrated waveguide (SIW) are proposed and researched. The proposed filters are based on a conventional box-section structure with considering bypass/constant/frequency-dependent coupling (FDC) in the diagonal cross-coupling path to construct new filtering responses. Based on the different type of the cross-coupling path, the frequency response of each proposed structure is analysed and presented, which indicates that the proposed filters have flexible response in terms of finite transmission zeros (FTZs). The proposed filters can realise generalised Chebyshev responses with one/two/three FTZs at arbitrary positions. Moreover, one FTZ may be produced by using bypass coupling and direct inductive coupling window to improve lower stopband performance, which is verified by a coupling matrix. For the demonstration, three quasi-elliptic response filters were designed, fabricated, and measured. Good agreement is achieved between simulated and measured results.

Design of a <inline-formula> <tex-math notation="LaTeX">$W$ </tex-math> </inline-formula>-Band GaAs-Based SIW Chip Filter Using Higher Order Mode Resonances

In this letter, an on-chip bandpass filter is designed and implemented based on a 70- $\mu \text{m}$ GaAs substrate integrated waveguide (SIW) technique for W-band integrated transceiver applications. To achieve a high-frequency selectivity, a modal bypass coupling realized by higher order mode resonators is introduced in the SIW filter, and two designable transmission zeros are generated accordingly. The presented filter has a center frequency of 92.7 GHz, with a 3-dB bandwidth of about 3.2 GHz. The measured out-of-band rejection is better than 30 dB at 90 and 95 GHz, respectively.

Effect of bypass coupling on droplet transfer in twin-wire indirect arc welding

The bypass coupling technique was employed on twin-wire indirect arc welding (TWIAW) to improve its penetration. In bypass coupling twin-wire indirect arc welding, the cathode current can be adjusted by changing the cathode-wire feeding speed. The melting efficiency increases with the cathode-wire current. At the same total current, the deposition and dilution rates of twin-wire indirect arc welding with bypass coupling is twice and a third those of conventional gas metal arc welding, respectively, which are good for low-heat input welding, such as surfacing. High-speed camera observation indicated that the cathode droplet transfer mode changes from free transfer to contact transfer with the increase of the cathode-wire current. The repulsion force of the anode droplet to the cathode wire increases with the increase of the cathode-wire current.

Narrowband Substrate Integrated Waveguide Bandpass Filter With High Selectivity

In this letter, a highly selective narrowband bandpass filter (BPF) is presented in substrate integrated waveguide (SIW) technology. Higher order TE301 resonators are used to utilize their high unloaded Q-factors. A midline feeding scheme together with a bypass coupling provides three transmission zeros (TZs). Two of the zeros can be placed at band edges for high selectivity. A three-pole BPF with 3-dB fractional bandwidth of 1.1% at $f_{\mathrm {\mathbf {0}}} = 8.25$ GHz is fabricated. It provides at least 35-dB attenuation over 2 GHz above and below the passband starting from $f_{0} \pm 0.15$ GHz.

Improved Dynamic Range of Microwave Power Sensor by MEMS Cantilever Beam

This letter reports a microwave power sensor with improved dynamic range based on MEMS cantilever beam. The proposed power sensor is manufactured using GaAs microwave monolithic integrated circuit (MMIC) technology. In this design, a cantilever by-pass coupling structure is adopted for high power detection, while the terminating thermoelectric sensor is utilized for low power detection. The novelty of the proposed device is that the concatenation of a cantilever beam and the thermoelectric sensor allows the ultra-high dynamic range power detection. Measurement results show that the sensitivities are 0.0315, 0.0261, and 0.0237 mV/mW at 1, 2, and 3 GHz for input power from 0.1 to 100 mW, respectively. For input power from 100 mW to 1W, the sensitivities are 2.398, 3.753, and 5.416 μV/mW at 1, 2, and 3 GHz, respectively. This compact power sensor has the potential prospect for dynamic range application.

Coupling topology of substrate integrated waveguide filter using unequal length slots with non‐resonating nodes

A novel coupling topology of substrate integrated waveguide filter with unequal-length slots is proposed. This filter consists of two resonators and a pair of unequal-length slots, which can be considered as two-stage bypass coupling resonators. There exist two resonant modes (TE101 and TE102) in each resonator. TE101 mode is coupled by the long slot, and TE102 mode is coupled by the short slot, which can achieve two resonant modes couplings between adjacent cavities. This structure uses TE102 mode to design the centre frequency of the passband and regards TE101 mode as spurious response. As a result, this filter leads to three transmission zeros (TZs), two TZs locate above the passband and one TZ is below the passband. The filter is fabricated and measured, the measured results agree well with simulated ones.

WR-3 Band Quasi-Elliptical Waveguide Filters Using Higher Order Mode Resonances

Two types of WR-3 band quasi-elliptical waveguide bandpass filters (BPFs) using higher order mode resonators are presented based on physical cross coupling and modal bypass coupling, respectively. Under the situation of physical folded structure, a TE102-mode in an oversized waveguide resonator is utilized to reverse the magnetic field direction of main path to implement a negative cross coupling (Filter-I). Limited to the structure of Filter-I itself, the simulated 3 dB fractional bandwidth (FBW) of 8.5% is slightly narrower than desired 10% FBW. For the other case, two TE101/TE201 overmode resonant cavities with suitable input and output coupling locations are employed to generate two transmission zeros in the vicinity of the passband through modal bypass couplings (Filter-II). The benefit from the realization of the wideband source and load couplings in the fringe first and fourth oversized cavities is that the FBW of 10% is achieved in the Filter-II. The two BPFs fabricated by computer numerical control milling technology exhibit an insertion loss (IL) of about 0.7 dB and a 3 dB FBW of 8.77% centered at 257.7 GHz (Filter-I), IL of around 0.5 dB, and FBW of 9.83% with center frequency of 256.3 GHz (Filter-II), which are all in good agreement with the simulations. The performance of the two BPFs based on one or two oversized waveguide resonators is highlighted comparing with the reported similar terahertz waveguide filters.

Propagating Waveguide Filters Using Dielectric Resonators

In this paper a new class of propagating waveguide in-line pseudoelliptic filters exploiting dielectric resonators is presented. The basic structure is a singlet, which is implemented by a ${\rm TE}_{01 \delta}$ mode dielectric resonator placed into a rectangular waveguide above cutoff. Couplings are controlled by a proper positioning of the puck. The fundamental propagating mode of the waveguide is exploited to both excite and bypass the resonator so as to obtain bypass coupling capability, allowing the generation of transmission zeros. Higher order filters are obtained by cascading singlets through quarter-wave or half-wave waveguide sections. The quarter-wave section behaves as an admittance inverter, while the half-wave section behaves as a resonator, the latter resulting in filters which combine dielectric and cavity resonators. Thanks to this combination, unique performances such as wide bandwidth and sharp transition bands can be obtained. To validate the proposed method a third-order filter with 2.3% fractional bandwidth (FBW) and a fifth-order filter with 8.15% FBW have been designed and manufactured, thus demonstrating the approach feasibility.