Development of an automatic beam focus system for electron beam welding

Hiramoto, Seigo; Ohmine, Megumi; Sakamoto, Masahiko

doi:10.1080/09507119109447844

Cited by 5 publications

(3 citation statements)

References 1 publication

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“…047105 (2014) are the subjects of many research papers. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Similar investigations have been executed in the field of laser welding. [16][17][18] This research has been directed towards determining correlations between the parameters of secondary signals, dynamics of the processes in the keyhole, and the results of the technological processes.…”

Section: Introductionmentioning

confidence: 99%

Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

et al. 2014

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Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low-and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 10 16 m −3 , which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A · m −2 , i.e. 8 mA for a 3-10 cm 2 collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole. C 2014 Author(s)

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Section: Introductionmentioning

confidence: 99%

Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

et al. 2014

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“…Al-Mg alloys are widely used for structural parts due to their high strength to weight ratio and good corrosion resistance. The laser welding of Al-Mg alloys has been studied by many researchers along with arc welding; degradation of weld properties and weld defects including solidification cracking and porosity formation have been reported [1][2][3]. The effect of weld metal composition on the cracking tendency during laser welding of aluminum alloys has not been clearly understood, because the quantitative assessment technique of solidification cracking has not been established well.…”

Section: Introductionmentioning

confidence: 99%

CW CO<sub>2</sub> Laser Welding of Al-Mg Alloys with Filler Wires

Yoon

Wallach

2008

MSF

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The CW CO2 laser weldability of various Al-Mg alloys was investigated in terms of weld strength, ductility, Vickers hardness, formability and solidification cracking tendency when both autogenous and wire feed welding were made. Tensile strength of the laser welds was lower than that of the corresponding base metals, and it was linearly proportional to the Mg content of the weld metal. Formability and ductility of Al-Mg alloy laser welds were lower than those of corresponding base alloys as well. As for the weld solidification structure, as the Mg content increased in the weld metal, more equiaxed grains developed. Hence, softening of weld metal and solidification cracking were decreased in the weld metal containing higher Mg. Solidification cracking of Al-Mg alloy laser welds showed the highest susceptibility at 1.6 to 1.9wt.% Mg, and it decreased with further increase of Mg content.

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“…In [13], X-rays are used to control the EBW parameters. In [14,15], there is a description of the correlation between focusing mode and the average values and amplitudes of the reflected and secondary currents, ionic current, as well as X-ray density. These results helped Mitsubishi Electric Corporation develop automatic electronic-beam focus control systems [15], which use electronic-beam with focusing control at low power as reference points.…”

Section: Introductionmentioning

confidence: 99%

Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

Трушников

Belenkiy

Shchavlev

et al. 2012

Sensors

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Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.

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Development of an automatic beam focus system for electron beam welding

Cited by 5 publications

References 1 publication

Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

CW CO<sub>2</sub> Laser Welding of Al-Mg Alloys with Filler Wires

Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

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