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

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.

[1]  Yi Zhang,et al.  Spectroscopic measurements of plasma inside the keyhole in deep penetration laser welding , 2005 .

[2]  G. Mladenov,et al.  Potential distribution and space-charge neutralization in technological intense electron beams — an overview , 2001 .

[3]  D. K. Pratihar,et al.  Optimization of bead geometry in electron beam welding using a Genetic Algorithm , 2009 .

[4]  Seiji Katayama,et al.  In-process monitoring and feedback control for stable production of full-penetration weld in continuous wave fibre laser welding , 2009 .

[5]  C. Felser,et al.  High spin polarization in Co2CrAl–Cr superlattice , 2009 .

[6]  Dilip Kumar Pratihar,et al.  Study on electron beam butt welding of austenitic stainless steel 304 plates and its input–output modelling using neural networks , 2011 .

[7]  E. Koleva,et al.  Electron beam weld parameters and thermal efficiency improvement , 2005 .

[8]  P. V. Remoortere.  Methodes et techniques de traitement du signal et applications aux mesures physiques : J. Max: 1977, 379 pages, Masson, Paris , 1979 .

[9]  Antonio Ancona,et al.  Plasma Plume Oscillations Monitoring during Laser Welding of Stainless Steel by Discrete Wavelet Transform Application , 2010, Sensors.

[10]  G. Mladenov,et al.  Formation and expansion of the plasma column under electron beam–metal interaction , 2005 .

[11]  An enhanced Faraday cup for rapid determination of power density distribution in electron beams , 2001 .

[12]  W. R. Buckland,et al.  Statistics and Experimental Design in Engineering and the Physical Sciences , 1978 .

[13]  J. Max.  Méthodes et techniques de traitement du signal et application aux mesures physiques. Tome 2 , 1981 .

[14]  Katayama Seiji,et al.  Study of Dynamic Features of Surface Plasma in High-Power Disk Laser Welding , 2012 .

[15]  Christian Kägeler,et al.  Frequency-based analysis of weld pool dynamics and keyhole oscillations at laser beam welding of galvanized steel sheets , 2010 .

[16]  Z. Tian,et al.  Controlling the plasma of deep penetration laser welding to increase power efficiency , 2001 .

[17]  Peter Norman,et al.  Analysis of the Keyhole and Weld Pool Dynamics by Imaging Evaluation and Photodiode Monitoring , 2009 .

[18]  Francesco P. Mezzapesa,et al.  Closed Loop Control of Penetration Depth during CO2 Laser Lap Welding Processes , 2012, Sensors.

[19]  Sophocles J. Orfanidis,et al.  Optimum Signal Processing: An Introduction , 1988 .

[20]  Alexander Kaplan,et al.  Signal overlap in the monitoring of laser welding , 2010 .

[21]  Pablo Juan Garcia,et al.  Measurement of mortar permittivity during setting using a coplanar waveguide , 2010 .

[22]  Katarzyna Olszewska,et al.  Control of the electron beam active zone position in electron beam welding processes , 2004 .

[23]  T. DebRoy,et al.  Heat Transfer and Fluid Flow during Electron Beam Welding of 304L Stainless Steel Alloy , 2009 .

[24]  T M Mustaleski,et al.  Transferring Electron Beam Welding Parameters Using the Enhanced Modified Faraday Cup , 2007 .

[25]  T. DebRoy,et al.  Heat transfer and fluid flow during electron beam welding of 21Cr–6Ni–9Mn steel and Ti–6Al–4V alloy , 2009 .

[26]  V. M. Yazovskikh,et al.  Control of electron beam welding using plasma phenomena in the molten pool region , 1997 .

[27]  Zhang Xudong,et al.  Double closed-loop control of the focal point position in laser beam welding , 2003 .

[28]  A device for controlling focusing and penetration depth on the basis of inherent X-radiation in electron beam welding with modulation of the focusing level , 1997 .