Development Of Accompanying Annealing System For Electron Beam Fused Additive Manufacturing

Electron beam fuse additive manufacturing technology is widely used in aerospace and other industrial fields.However,in the manufacturing process,due to the large power of the electron beam current,the heat input is relatively concentrated,the temperature gradient of each part of the shaped parts is large,which will cause deformation.In order to restrain parts deformation during the E-Beam fuse additive manufacturing process and improve the forming quality,the design of an accompanying annealing system for the E-Beam fuse additive manufacturing process was carried out.This paper mainly studied the acquisition technology of magnetic field with high uniformity and high response frequency,completed the development of the scanning coil drive power amplifier circuit and focus drive circuit,completed the research of high frequency deflection scanning signal acquisition technology.At the same time,the development of servo array temperature measurement system,overall system integration and performance test analysis were carried out.Aiming at the problems of low scanning frequency of electron beam deflection and uneven magnetic field of the scanning coil,an electron beam deflection scanning coil based on the basic principle of Helmholtz coil was developed.It is showed that when the coil passed a 3A current,the magnetic induction intensity is not less than 1.1mT at each point inside the coil,the maximum difference is 0.18mT,the magnetic field strength distribution is relatively uniform inside the scanning coil,which can meet the magnetic field strength and magnetic field uniformity required for highfrequency deflection scanning of the electron beam.A high-frequency scan drive circuit and a focus drive circuit based on the basic principle of PID control has been developed.After testing,the scan drive circuit drives the scan coil,the current can reach ± 3A,the change speed can reach 30 kHz,the current rising edge and falling edge time are both 17?S.The focus drive circuit continuous output 1A current for up to 3 hours during the testing process,due to the design of closed-loop feedback control,the output current floats only 0.008A,and the stability of the circuit is good.The scanning signal generation control program has been written based on Lab VIEW virtual instrument,which can read the G code file in TXT format,and the scanning path can be arbitrary changes,the program operation is simple and clear.The compression spring K-type thermocouple has been used to design the accompanying dynamic array temperature measurement system,which overcomes the problems of limited infrared temperature measurement area,equipment damage in vacuum environment,and lens contamination by metal vapor.And the temperature data acquisition control program based on Lab VIEW has been written,which can be easy to operate.Based on the above technology,the electron beam fuse additive manufacturing accompanying annealing system is integrated into the EB equipment.Through experiments,it has been found that the scanning is used at high voltage 50kV,beam current 20mA,working distance 500mm,scanning frequency 15kHz.The temperature field obtained is relatively uniform by linear vertical adding the edge-profiled contour-compensated scanning method,with a maximum temperature difference of 12.5?,and the best deformation restrain effect,with a maximum deformation amount of 1.81mm.