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

Abstract

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.

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

“…15,38 For deep penetration of the beam in the keyhole, due to collisions between the charged particles and neutral atoms, the plasma fluctuations are depressed. 37 For the elevation of the position of the beam-wall interaction zone in the keyhole, the amplitude of the high-frequency component of the collected current increases.…”

“…This additional delay time must be accounted for the study and control of EBW using the method of synchronous accumulation of the high-frequency components of the current collected by plasma. 38 …”

Benefits And Prospects Of Laser Welding Application In Vacuum

“…In order to overcome the obstacle, we can apply the methods widely used in technologies of electron beam welding eliminating root defects. These methods are: periodic impacts on a beam [6][7], the choice of optimum focusing [8][9][10], etc.…”

Oscilation of Electron Beam During Electron Beam Welding for Improving Weld Root and Easymenting Melt-Through Mode Control

“…Однако точность регулиро-вания в этом случае зависит от параметров входных фильтров измери-тельной системы и отношения величины сигнала к порогу его ограничения формирующим каскадом. Кроме того, в качестве контро-лируемого параметра может быть использовано усредненное значение продолжительности импульса сквозного тока, когда величина скважно-сти делится на количество импульсов за единицу времени [12][13][14][15].…”