Energy Density Distribution and Temperature Closed-Loop Control in Electron Beam Processing

Various electron beam (EB) processing methods such as EB brazing, surface modification, heat treatment, etching, evaporation coating and quick manufacture, etc. require that the energy distribution and processing temperature be controlled. In this study, the energy distribution control was realized by EB scanning trajectory pattern control, and the temperature control was realized by the combined use of fuzzy logic and PID control. These were integrated into one system. To obtain large deflection angle of EB, an external deflection coil was used. The scanning trajectory pattern was the synthesization of deflections of EB in X and Y directions, and each of the deflections was controlled by an analog. Because of high energy density of the EB, and consequently high sensitivity of weldment temperature to the beam current, closed-loop control of processing temperature is indispensable, which was realized in this paper. Satisfactory transient and steady-state specifications were obtained. The brazing of a specially designed specimen verified the effectiveness of the method.