Abstract: The calibration accuracy of the electron gun directly affects the forming accuracy of the electron beam selective melting process. Aiming at the shortcomings of the traditional manual calibration method in terms of accuracy and reliability, an automatic calibration method based on the mean value estimation model of circular hole is proposed, and the estimation error of the model under different radius of circular holes is analyses. The calibration error of the deflection voltage of the electron beam gun is calculated under the conditions of different beam spot diameters, differences between the long and short axes of the beam spot, the angle of deflection of the beam spot's long axis, and the distance of the line, and the experiments on automatic calibration of the deflection voltage of the electron beam gun are designed to validate the reliability and calibration accuracy of the method. The reliability and calibration accuracy of the method are verified. The experimental results show that compared with the manual calibration, the automatic calibration method proposed reduces the mean straightness error of the X-direction scanning track from 0.3983 mm to 0.1154 mm, and the mean straightness error of the Y-direction scanning track from 0.5818 mm to 0.0951 mm, with an overall reduction of more than 60% in the automatic calibration error, which verifies that the method has a higher reliability and calibration accuracy than the manual calibration method. higher reliability and calibration accuracy than the manual calibration method.

Key words: electron gun, center-of-circle mean model, electron gun deflection voltage automatic calibration, calibration accuracy