scholarly journals Molten Pool Behaviors in Double-Sided Pulsed GMAW of T-Joint: A Numerical Study

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1594
Author(s):  
Haicang Zhang ◽  
Chunsheng Wang ◽  
Sanbao Lin
Keyword(s):  
Molten Pool ◽  
High Efficiency ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Basic Flow ◽  
Feed Speed ◽  
Complex Flow ◽  
Pool Surface ◽  
Wire Feed Speed ◽  
Wire Feed

The T-joint is one of the essential types of joints in aluminum welded structures. Double-sided welding is a preferable solution to maintain high efficiency and avoid significant distortion during T-joint welding. However, interactions between double-sided molten pools make flow behaviors complicated during welding. Numerical simulations regarding molten pool behaviors were conducted in this research to understand the complex flow phenomenon. The influences of wire feed rates and torch distances were simulated and discussed. The results show that droplet impinging drives the fluid to flow down to the root and form a frontward vortex. Marangoni stress forces the fluid to form an outward vortex near the molten pool boundary and flatten the concave-shaped molten pool surface. With an increased wire feed speed, the volume of the molten pool increases, and the root fusion is improved. With an increased torch distance, the width of the front molten pool decreases while the length increases, and the rear molten pool size decreases slightly. Both wire feed speeds and the torch distances have limited influences on the basic flow characteristics.

Correlation between wire feed speed and external mechanical constraint for enhanced process stability in underwater wet flux-cored arc welding

2018 ◽  
Vol 233 (10) ◽  
pp. 2061-2073 ◽  
Author(s):  
Jianfeng Wang ◽  
Qingjie Sun ◽  
Jiangkun Ma ◽  
Peng Jin ◽  
Tianzhu Sun ◽  
...  
Keyword(s):  
Welding Process ◽  
Electrical Signal ◽  
Feed Speed ◽  
Process Stability ◽  
Underwater Wet Welding ◽  
Extinction Process ◽  
Flux Cored Arc Welding ◽  
Wire Feed Speed ◽  
Wire Feed ◽  
Mechanical Constraint

It is a great challenge to improve the process stability in conventional underwater wet welding due to the formation of unstable bubble. In this study, mechanical constraint method was employed to interfere the bubble generated by underwater wet welding, and the new method was named as mechanical constraint assisted underwater wet welding. The aim of the study was to quantify the combined effect of wire feed speed and condition of mechanical constraint on the process stability in mechanical constraint assisted underwater wet welding. Experimental results demonstrated that the introduction of mechanical constraint not only suppressed the bubble without floating but also stabilized the arc burning process. The degree of influence of mechanical constraint, which changed with wire feed speed, played an important role during the mechanical constraint assisted underwater wet welding process. For all wire feed speeds, the fluctuations of welding electrical signal were decreased through introduction of mechanical constraint. The difference in the proportion of arc extinction process between underwater wet welding and mechanical constraint assisted underwater wet welding became less with increasing wire feed speed. At wire feed speed lower than 7.5 m/min, the improvement of process stability was very significant by mechanical constraint. However, the further improvement produced limited effect when the wire feed speed was greater than 7.5 m/min. The observation results showed that a better weld appearance was afforded at a large wire feed speed, corresponding to a lower variation coefficient.

Flow Characteristics in a Three-Dimensional Rectangular Channel With a Pair of Ribs Placed Symmetrically at the Channel Walls

2000 ◽  
Author(s):  
M. Singh ◽  
P. K. Panigrahi ◽  
G. Biswas
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Energy Equations

Abstract A numerical study of rib augmented cooling of turbine blades is reported in this paper. The time-dependent velocity field around a pair of symmetrically placed ribs on the walls of a three-dimensional rectangular channel was studied by use of a modified version of Marker-And-Cell algorithm to solve the unsteady incompressible Navier-Stokes and energy equations. The flow structures are presented with the help of instantaneous velocity vector and vorticity fields, FFT and time averaged and rms values of components of velocity. The spanwise averaged Nusselt number is found to increase at the locations of reattachment. The numerical results are compared with available numerical and experimental results. The presence of ribs leads to complex flow fields with regions of flow separation before and after the ribs. Each interruption in the flow field due to the surface mounted rib enables the velocity distribution to be more homogeneous and a new boundary layer starts developing downstream of the rib. The heat transfer is primarily enhanced due to the decrease in the thermal resistance owing to the thinner boundary layers on the interrupted surfaces. Another reason for heat transfer enhancement can be attributed to the mixing induced by large-scale structures present downstream of the separation point.

Research of Automatic Welding Machine Controlling System Based Single-Chip

2012 ◽  
Vol 214 ◽  
pp. 700-704
Author(s):  
Jin Hu Song
Keyword(s):  
Production Efficiency ◽  
Feed Speed ◽  
Automatic Welding ◽  
Single Chip ◽  
Interface Circuit ◽  
Welding Machine ◽  
Welding Technology ◽  
Controlling System ◽  
Wire Feed Speed ◽  
Wire Feed

In this paper, a scheme for the structure and controlling design of an all-position automatic welding machine is studied, and also the automatic welding systemis explored in depth. In this system, the C8051F020 single chip is used as the controller and the DC servo-motor as the executive component. Through the interface circuit and software program of the single chip, the system can control and harmonize the wire-feed speed as well as the tread and swing of the welding tractor, and can meet the needs of the all-position welding technology, hence realizing the automation of welding, and increasing the welding production efficiency.

scholarly journals Balancing WAAM Production Costs and Wall Surface Quality through Parameter Selection: A Case Study of an Al-Mg5 Alloy Multilayer-Non-Oscillated Single Pass Wall

2019 ◽  
Vol 3 (2) ◽  
pp. 32 ◽  
Author(s):  
Yuri Yehorov ◽  
Leandro João da Silva ◽  
Américo Scotti
Keyword(s):  
Deposition Time ◽  
Travel Speed ◽  
Production Costs ◽  
Constant Current ◽  
Feed Speed ◽  
Surface Waviness ◽  
Single Pass ◽  
Target Wall ◽  
Wire Feed Speed ◽  
Wire Feed

The purpose of the study was to propose a strategy to assess the potential reduction of the production cost during wire+arc additive manufacturing (WAAM) based on the combination of wire feed speed (related to deposition rate) and travel speed (related to deposition time). A series of experiments, using a multilayer-non-oscillated single pass wall made of an Al-Mg alloy, was conducted. The quality of the wall was assessed through the lateral surface waviness and top layer undulation. The concepts of Surface Waviness and Buy-to-Apply indices were introduced. Initially, the range of travel speed (TS) that provided layers with acceptable quality was determined for a given wire feed speed (WFS), corresponding to a constant current. Then, the effect of the increase of production capacity of the process (though current raising, yet maintaining the ratio WFS/TS constant) on the wall quality for a given condition within the TS range was assessed. The results showed that the useful range of TS prevents too rough a waving surface below the lower limit and top surface undulation over the higher limit. However, inside the range, there is little quality variation for the case under study. Finally, simulations of deposition time were developed to demonstrate the weight of the TS on the final deposition time and wall quality as a function of a target wall width. This respective weight showed the existence of a complex and unpredictable, yet determined, power of a combination of TS, target wall geometry, and dead time between subsequent layers. It was verified to be possible to find optimized TS as a function of different target geometries.

scholarly journals Flow Characteristics in Volute of a Double-Suction Centrifugal Pump with Different Impeller Arrangements

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 669 ◽  
Author(s):  
Yu Song ◽  
Honggang Fan ◽  
Wei Zhang ◽  
Zhifeng Xie
Keyword(s):  
Centrifugal Pump ◽  
High Efficiency ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Weighted Average ◽  
Complex Flow ◽  
Suction Pump ◽  
Impeller Outlet ◽  
Large Flow ◽  
Dominant Frequencies

As an important type of centrifugal pump, the double-suction pump has been widely used due to its high efficiency region and large flow rate. In the present study, the complex flow in volute of a double-suction centrifugal pump is investigated by numerical simulation using a re-normalization group (RNG) k-ε model with experimental validation. Axial flows are observed in volute near the impeller outlet and compared with four staggered angles. The net area-weighted average axial velocities decrease as the staggered angle increases. The axial flows are mainly caused by the different circumferential pressure distribution at the twin impeller outlet. The dominant frequencies of the axial velocities for different staggered angles are fBP and its harmonic. The pressure fluctuations in most regions of the volute are obtained by superimposing the pressure generated by the two impellers.

Numerical study of transonic cavity flows using large-eddy and detached-eddy simulation

2007 ◽  
Vol 111 (1117) ◽  
pp. 153-164 ◽  
Author(s):  
P. Nayyar ◽  
G. N. Barakos ◽  
K. J. Badcock
Keyword(s):  
Energy Content ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Promising Alternative ◽  
Eddy Simulation ◽  
Massively Separated Flows ◽  
Large Eddy

Numerical analysis of the flow in weapon bays modelled as open rectangular cavities of length-to-depth (L/D) ratio of 5 and width-to-depth (W/D) ratio of 1 with doors-on and doors-off is presented. Flow conditions correspond to Mach and Reynolds numbers (based on cavity length) of 0·85 and 6·783m respectively. Results from unsteady Reynolds-averaged Navier-Stokes (URANS), large-eddy simulation (LES) and detached-eddy simulation (DES) are compared with the simulation methods demonstrating the best prediction of this complex flow. It was found that URANS was not able to predict the change of flow characteristics between the doors-on and doors-off configurations. In addition, the energy content of the cavity flow modes was much better resolved with DES and LES. Further, the DES was found to be quite capable for this problem giving accurate results (within 3dB of) experiments and appears to be a promising alternative to LES for modelling massively separated flows.

Robust Speed Control Algorithm of Welding Wire Feed System Based on the State Space Model

2014 ◽  
Vol 494-495 ◽  
pp. 1358-1363
Author(s):  
Xiu Mei Wu ◽  
Li Min Sha ◽  
Tao Zi Si ◽  
Lei Jiang
Keyword(s):  
Robust Control ◽  
Control Algorithm ◽  
State Space Model ◽  
Feed Speed ◽  
Welding Quality ◽  
Welding Robot ◽  
Welding Wire ◽  
Space Model ◽  
Wire Feed Speed ◽  
Wire Feed

In the modern welding technology of metal materials, the welding robot is a very important factor. And the welding wire feeding device is a very important part of the welding robot. The welding wire feed systems stabilization and reliability is essential for the welding quality. The resistance is caused by the draw of welding wire and other factors, which is highly nonlinear and stochastic. The wire feed rate and welding quality will be severely affected by the resistance. This paper investigates the method controlling the system according to the observations of the resistance, speed and other factors. There are the complex environmental factors in the welding process, such as the strong magnetic field and high current field, which are random. So the robust control algorithm based on the state space model is designed to keep the welding wire feed speed stable under disturbances. The robust control method can improve the speed of response and eliminate the effect of wire feed resistance to the wire feed speed. Even when disturbed, the system can quickly reach a stable wire feed speed.

scholarly journals A Parametric Study of Additive Manufacturing Process: TA6V Laser Wire Metal Deposition

2021 ◽  
pp. 15-20
Author(s):  
Valentine Cazaubon ◽  
Audrey Abi Akle ◽  
Xavier Fischer
Keyword(s):  
Additive Manufacturing ◽  
Laser Power ◽  
Pearson Correlation ◽  
Metal Deposition ◽  
Feed Speed ◽  
New Process ◽  
Wire Feed Speed ◽  
Subtractive Manufacturing ◽  
Working Principle ◽  
Wire Feed

AbstractAdditive Manufacturing has proven to be an economically and industrially attractive process in building or repairing parts. However, the major issue of this new process is to guarantee a mechanical behavior identical to the subtractive manufacturing methodologies. The work, presented in this paper, is centered on the Laser Wire Metal Deposition (LMD-w) method with the metallic alloy TA6V. Its working principle is to fuse a coaxial wire on a substrate with a laser as a heat source. To better understand the interaction between the input parameters (Laser Power, Wire Feed Speed and Tool Speed) and the clad geometry output variables (Height, Width and Contact Angle) and the substrate displacement, we have realized an experimentation. We printed 9 clads according Taguchi’s experimental design. Pearson correlation coefficient and Fisher test performed on the experimental measures showed as main result: Tool Speed is the parameter with the most significant influence on the output variables.

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