scholarly journals Mathematical Analysis of the Influence of the Flux-Cored Wire Chemical Composition on the Electrical Parameters and Quality in the Underwater Wet Cutting

2021 ◽  
Vol 21 (1) ◽  
pp. 77-89
Author(s):  
S. Parshin ◽  
A. Levchenko ◽  
P. Wang ◽  
A. Maystro
Keyword(s):  
Probability Density ◽  
Welding Current ◽  
Cutting Process ◽  
Cored Wire ◽  
Cycle Times ◽  
Current Voltage ◽  
Cyclical Process ◽  
And Performance ◽  
The Stability ◽  
Cored Wires

Abstract The paper presents research in the field of underwater wet cutting with the use of flux-cored wires in order to improve the quality and performance. The research has resulted into the development of gas and slag systems for flux-cored wires and determination of, optimal parameters for cutting stability and quality. The underwater wet cutting mechanism is a cyclical process with the formation of periodic keyholes in metal, and it consists of operating and idle cycles. Efficiency of the cutting process can be determined by analyzing cycle times, welding current, voltage, power and a number of short circuits. To assess the stability and efficiency of the underwater wet cutting process, the authors have developed the method for analyzing oscillograms to calculate the probability density of current, voltage and power. To determine the quality of cutting, the authors have provided a criterion based on the ratio of the voltage probability density in the idle and operating cycles.

scholarly journals Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4655
Author(s):  
Sergey G. Parshin ◽  
Alexey M. Levchenko ◽  
Pengfei Wang
Keyword(s):  
Welding Current ◽  
Exothermic Effect ◽  
Metal Oxidation ◽  
Cored Wire ◽  
Aisi 304L ◽  
Negative Effect ◽  
304L Steel ◽  
Cored Wires ◽  
Metallurgical Processes ◽  
Underwater Cutting

This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO3, FeCO3, and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe3O4, MoO2, WO2 oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na3AlF6 cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344–402 A with a voltage of 36–39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360–406; 240 A, with a voltage of 35–37; 38 V, respectively, with the optimal composition of flux-cored wire: 50–60% FeCO3 and KNO3, 20–30% aluminum, 20% Na3AlF6. Application of flux-cored wires of the KNO3-FeCO3-Na3AlF6-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5–4.7 mm.

Mechanized Welding with Metal Cored Wire

2020 ◽  
Vol 1157 ◽  
pp. 113-122
Author(s):  
Andrey A. Golyakevich ◽  
Leonid N. Orlov ◽  
Sergey Yu. Maksimov
Keyword(s):  
High Performance ◽  
Welding Process ◽  
Global Market ◽  
Cored Wire ◽  
Global Trends ◽  
Wide Range ◽  
Mechanized Welding ◽  
The Stability ◽  
Welding Consumables ◽  
Cored Wires

Currently, there is a steady upward trend in the consumption of flux-cored wires in the global market of welding consumables. One of the rapidly developing technologies for the manufacture of metal structures is shielded gas arc welding with flux-cored wire with a metal core. According to the technology of use, metal cored wires do not differ from solid wires, and even surpass them in some technological characteristics. Taking into account global trends in the development of mechanized welding and the lack of domestic analogues, LLC TM.VELTEK has developed and mastered the manufacturing of high-performance metal cored wire TMB5-MK for welding in mixtures of 82% Ar + 18% CO2, 90% Ar + 10% CO2. The research aimed to study the features of the process of welding with metal cored wire compared to welding with solid wire. It has been established that metal cored wire provides high stability of arc burning in a wide range of welding modes. When welding at the same conditions in the optimal range, the index of stability of arc burning when using solid wire Sv-08G2S is 3 times lower. At the same time, the TMV5-MK wire provides a reduction in spatter losses, an increase in welding productivity and high mechanical properties of the weld metal. It is shown that the stability of the welding process is significantly affected by the electrodynamic properties of the power source and this factor must be taken into account when evaluating the welding and technological properties of welding wires and developing recommendations for their use.

Enhancements of Non-contact Measurements of Electrical Waveforms on the Proximity of a Signal Surface Using Groups of Pulses

2002 ◽  
Author(s):  
Fenglei Du ◽  
Greg Bridges ◽  
D.J. Thomson ◽  
Rama R. Goruganthu ◽  
Shawn McBride ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Signal To Noise Ratio ◽  
Electrostatic Force ◽  
Single Pulse ◽  
Electric Signal ◽  
Measurement Instruments ◽  
Cycle Times ◽  
Force Microscopy ◽  
And Performance

Abstract With the ever-increasing density and performance of integrated circuits, non-invasive, accurate, and high spatial and temporal resolution electric signal measurement instruments hold the key to performing successful diagnostics and failure analysis. Sampled electrostatic force microscopy (EFM) has the potential for such applications. It provides a noninvasive approach to measuring high frequency internal integrated circuit signals. Previous EFMs operate using a repetitive single-pulse sampling approach and are inherently subject to the signal-to-noise ratio (SNR) problems when test pattern duty cycle times become large. In this paper we present an innovative technique that uses groups of pulses to improve the SNR of sampled EFM systems. The approach can easily provide more than an order-ofmagnitude improvement to the SNR. The details of the approach are presented.

scholarly journals Analytical Modeling and Design of Novel Conical Halbach Permanent Magnet Couplings for Underwater Propulsion

2021 ◽  
Vol 9 (3) ◽  
pp. 290
Author(s):  
Yukai Li ◽  
Yuli Hu ◽  
Youguang Guo ◽  
Baowei Song ◽  
Zhaoyong Mao
Keyword(s):  
Permanent Magnet ◽  
Analytical Calculation ◽  
Underwater Propulsion ◽  
Conical Structure ◽  
Torque Analysis ◽  
Dynamic Seal ◽  
And Performance ◽  
The Stability ◽  
Propulsion Unit ◽  
Force Calculation

Permanent magnet couplings can convert a dynamic seal into a static seal, thereby greatly improving the stability of the underwater propulsion unit. In order to make full use of the tail space and improve the transmitted torque capability, a conical Halbach permanent magnet coupling (C-HPMC) is proposed in this paper. The C-HPMC combines multiple cylindrical HPMCs with different sizes into an approximately conical structure. Compared with the conical permanent magnet couplings in our previous work, the novel C-HPMC has better torque performance and is easy to process. The analytical calculation method of transmitted torque of C-HPMC is proposed on the basis of torque calculation of the three common types of HPMCs. The accuracy of the torque calculation of the three HPMCs is verified, and the torque performance of the three HPMCSs of different sizes is compared and discussed. The “optimal type selection” method is proposed and applied in the design of C-HPMC. Finally, on the basis of torque analysis calculation and axial force calculation, a complete flowchart of the design and performance analysis of C-HPMC is described.

Adaptive attitude-tracking control of spacecraft considering on-orbit refuelling

2020 ◽  
pp. 014233122097313
Author(s):  
Yiqi Xu
Keyword(s):  
Tracking Control ◽  
Closed Loop ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Inertia Model ◽  
And Performance ◽  
Attitude Tracking Control ◽  
The Stability

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.

Nondestructive Test on Typical Roadway Supports of a Mine via Drilling Core and Ground Penetrating Radar

2011 ◽  
Vol 368-373 ◽  
pp. 2411-2416
Author(s):  
Jian Ping Han ◽  
Hai Peng Liu
Keyword(s):  
Ground Penetrating Radar ◽  
Geological Structure ◽  
Surrounding Rock ◽  
Potential Threat ◽  
Real Performance ◽  
Design Requirements ◽  
And Performance ◽  
The Stability ◽  
Ground Penetrating ◽  
Drilling Core

Temporary or permanent supports are necessary in underground construction for maintaining the stability and limiting the damage of surrounding rock. Due to the uncertainty of geological structure, the specificity of the underground environment as well as other factors, the quality and performance of supporting structure are often difficult to satisfy the design requirements, which not only seriously affects the normal construction and operation of mines but also has the potential threat to the safety of underground production. In order to investigate the influence of the unfavorable geologic environment on supporting concrete and evaluate the real performance of roadway supports of a mine, 17 typical projects were chosen and the strength of supporting concrete was detected by nondestructive drilling core method. The result shows that the strength is widely less than the design value. Furthermore, 4 projects of them were investigated by the ground penetrating radar (GPR) in order to evaluate the feasibility of GPR in the performance investigation of the roadway supports of a mine. The results indicate that ground penetrating radar is capable of measuring the thickness of the support, the distribution of rebars and the defects of the surrounding rock.

scholarly journals Structure and Properties of Coatings Made with Self Shielded Cored Wire

2016 ◽  
Vol 16 (3) ◽  
pp. 39-42 ◽  
Author(s):  
M. Gucwa ◽  
J. Winczek ◽  
R. Bęczkowski ◽  
M. Dośpiał
Keyword(s):  
Heat Input ◽  
Mining Industry ◽  
High Hardness ◽  
Properties Of Coatings ◽  
Cored Wire ◽  
Eutectic Carbides ◽  
Hard Particles ◽  
Wear And Corrosion ◽  
Flux Cored Arc Welding ◽  
Cored Wires

Abstract The welding technologies are widely used for design of protection layer against wear and corrosion. Hardfacing, which is destined for obtaining coatings with high hardness, takes special place in these technologies. One of the most effective way of hardfacing is using self shielded flux cored arc welding (FCAW-S). Chemical composition obtained in flux cored wire is much more rich in comparison to this obtained in solid wire. The filling in flux cored wires can be enriched for example with the mixture of hard particles or phases with specified ratio, which is not possible for solid wires. This is the reason why flux cored wires give various possibilities of application of this kind of filler material for improving surface in mining industry, processing of minerals, energetic etc. In the present paper the high chromium and niobium flux cored wire was used for hardfacing process with similar heat input. The work presents studies of microstructures of obtained coatings and hardness and geometric properties of them. The structural studies were made with using optical microscopy and X-ray diffraction that allowed for identification of carbides and other phases obtained in the structures of deposited materials. Investigated samples exhibit differences in coating structures made with the same heat input 4,08 kJ/mm. There are differences in size, shape and distribution of primary and eutectic carbides in structure. These differences cause significant changes in hardness of investigated coatings.

Analytical Modeling of Metal Transfer for GMAW in the Globular Mode

2008 ◽  
Author(s):  
U. Ersoy ◽  
S. J. Hu ◽  
E. Kannatey-Asibu
Keyword(s):  
Gas Metal Arc Welding ◽  
Variable Mass ◽  
Welding Current ◽  
Metal Transfer ◽  
Model Parameters ◽  
Feeding Rates ◽  
Cycle Times ◽  
Metal Arc Welding ◽  
Wire Feeding ◽  
Spring Coefficient

A lumped parameter dynamical model is developed to describe the metal transfer for gas metal arc welding (GMAW) in the globular mode. The oscillations of molten drop are modeled using a mass-spring-damper system with variable mass and spring coefficient. An analytical solution is developed for the variable coefficient system to better understand the effect of various model parameters on the drop oscillations. The effect of welding drop motion on the observed current and voltage signals is investigated and the model agrees well with the experimental results. Furthermore, the effect of wire feeding rate (or welding current) on the metal transfer cycle time is studied and the model successfully estimates the cycle times for different wire feeding rates.

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