Approximate entropy——a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding.

An analysis of the dynamic resistance and the instantaneous energy of the CO_2 arc welding process

A self-developed welding dynamic arc wavelet analyzer was adopted to analyze and assess the welding process of two CO2 arc welding machines. The experimental results indicate that the instantaneous energy can reflect the influence of the welding current and voltage on dynamic arc characteristic synthetically. Through calculating and analyzing the instantaneous energy, the energy during arc ignition and short circuit in CO2 welding process can be confirmed rationally, thus the foundation for the accurate design and control of the welding current and voltage can be provided. By reducing the ripple disturbance of the dynamic resistance, avoiding peak current and voltage waveform , and enhancing the transition frequency of short circuit suitably, the stability of the welding arc and the weld appearance can be improved.

Study on the measureto improve the arcstabilization in smaller current welding for the variable polarity GTAW powersource

The variable polarity power source which incorporates a constant current power and a secondary inverter does not need special apparatus for stabilizing arc. The pulse for stabilizing arc is created by the circuit structure itself. The paper analyzes the principle of acquiring the pulse, provides the better method to improve the arc stabilization under smaller welding current. Test shows the arc is highly stable , and the process has no high frequency electromagnetic interference, which is suitable for automatic welding case.

THE GASDYNAMIC AND ELECTROMAGNETIC FACTORS AFFECTING THE POSITION OF ARC ROOTS IN A TUBULAR ARC HEATER

The gasdynamic and electromagnetic factors affecting the position of arc roots in a tubular arc heater are analyzed.Magnitudes of the various factors are estimated through numerical modelling,and the overall action on the arc assessed.It is found that the actions on the arc in the rear electrode can be balanced in a stable manner and the arc root can be stabilized at a certain axial position.In the front electrode,the various factors cannot be balanced,and the are root can only stay within the electrode through the mechanism of recurrent shunting.These conclusions agree with experimental observations.

A study of arc stability of basic electrode in view of uniform design method

In order to develop a basic electrode with low fume and good usability, a uew slag system has been designed after analyzing several basic electrode slag systems. Then in view of uniform design method, arranging the experiment points by it, the influenced laws of the uew system coating compouents on the arc stability had been searched. In the formula, niue coating compouents were taken as independent variables and they were divided into six levels in all twenty-four experiments. The arc stability was taken as function and taken down the data when welding and then put them into the computer to be processed statistically. The analysis results give the mathematical model and trend diagrams between independent variables and the function. They indicate that the effects of many coating compouents on the arc stability are in the mutual form. The mutual effects between CaCO3 and BaF2, BaF2 and BaCO3 , increases the arc stability separately. While the mutual effects between CaF2 and iron powder, the square item of iron powder itself decreases the arc stability separately.

Research on the arc length and droplet transition control strategy for the full digital pulse MIG welding power supply

Arc length stability and droplet transition consistency are key factors for the pulse metal inert gas （MIG） welding quality. A new control strategy is proposed based on pulse current waveform adjustment to stabilize the welding process. After sufficient analysis of the droplet transition process, key current waveform parameters are refined that can affect the welding quality greatly. In order to achieve the optimal nonlinear control of parameters, the fuzzy controller is designed successfully with two inputs and three outputs in field programmable gate array （ FPGA ）, which occupies fewer resources than PID controller and has higher control performance. Experimental results show that the arc length can be adjusted fast in full range of welding current, the welding process is stable, the droplet transition has good consistency, and the welding quality is perfect.

Approximate entropy analysis of arc stability in VPPA-GMAW hybrid welding

Variable polarity plasma arc-gas metal arc welding(VPPA-GMAW)integrates the advantages of VPPA and GMAW,and it is particularly applied to weld thick-plates aluminum alloys.High-speed camera and data acquisition system were used to analyze the arc shape and the welding process electrical signal.According to the analysis of arc swing amplitude and the approximate entropy of arc voltage signal denoised by wavelet threshold method,the influence of VPPA frequency on the arc stability was studied.The results show that the approximate entropy of GMAW arc voltage decreases with the increase of VPPA frequency in a certain range,and the stability of the hybrid arc is significantly improved.The spectral analysis shows that the arc stability is reduced due to the resonance effect between the VPPA and the GMAW arc when the VPPA frequency closes to the GMAW arc pulse frequency.The results are helpful to understand hybrid welding mechanism and the selection of welding process parameters.

Arc Stability Characterization of Double Coated Electrodes for Hardfacing

The aim of this work is to establish the influence of the relative position of the alloy charge C-Cr-Mn in the structure of the coating of rutile electrodes for hardfacing,on the operational behavior(arc stability).For this,three variants of electrodes with similar chemical composition are elaborated in the metallic core and the coating,differentiating only in the relative position that occupies the alloy charge(C-Cr-Mn)in the structure of the coating:internal,external and homogeneous.For the development of the research,a completely random design is used.The operative characterization of the electrodes is performed in terms of the arc stability.In conclusion,it can be seen that the position of the alloy load influences the operation behavior(stability of the arc).The variant of internal alloy charge in the coating presents the better arc stability performance.

Analysis of Effects of the Arc Voltage on Arc Discharges in a Cathode Ion Source of Neutral Beam Injector

A hot cathode bucket ion source is used for the EAST（experimental advanced superconducting tokamak）neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.