Improvement of the positioning accuracy along the joint connection of details with the residual magnetization in electron beam welding

The effect of residual magnetization of the welded parts on the accuracy positioning of the electron beam along the joint connection is a complicated scientific and technical problem to achieve the high quality of welded joints in the aerospace industry, shipbuilding and power engineering. As a result of analysis of the magnetic fields of residual magnetization the authors obtained the mathematical model of their distribution in the space between the electron beam gun and the workpiece and also the quantitative characteristics of deflection of the electron beam from the joint connection were obtained. For obtaining the mathematical model, the authors use a method which is widely known in the literature. This method is based on the representation of residual magnetization as equivalent field of conductor with current. Comparative evaluation of experimental and calculated data confirms the adequacy of the modeling. The authors have developed a method and a functional diagram of the automatic compensation of the effect of magnetic fields on the accuracy of positioning of the electron beam along the joint connection in the process of electron beam welding. The system of automatic compensation includes a collimated X-ray sensor, which is designed for monitoring deflection of the electron beam from the optical axis of the electron beam gun. The X-ray sensor is placed on the electron beam gun. The collimation slit of X-ray sensor is aimed at the optical axis of the gun. The method of synchronous detection is used to process information from the X-ray sensor. Thus the signals of the first and second harmonics of the scanning frequency of the electron beam across the joint connection are allocated. The method of synchronous detection uses the technological scanning of electron beam across and along the joint connection. The technological scanning allows to provide the measurement of deflection of the electron beam and to expand opportunities to improve weld quality by controlling the distribution of energy in the heating spot. Automatic compensation of the action of magnetic fields of residual magnetization of welded product can reduce the positioning error of the electron beam on the joint connection in the weld root in 20-30 times.