Automatically controlled direct current degaussing device and method

The invention belongs to the technical field of degaussing, and relates to an automatically controlled direct current degaussing device and method for eliminating a welding seam magnetic field in the butt welding process of large steel plates in the industrial production. In the degaussing device, a pair of degaussing heads (1) are movably arranged at the front end of a welding machine, are symmetrically arranged at the two sides of a to-be-welded edge seam, and are connected with a positive electrode and a negative electrode of a programmable power supply (2), and the programmable power supply (2) supplies power through commercial power, so that a direct-current strong magnetic field is generated between the two demagnetizing heads (1). A Gauss meter (3) is connected with a PLC (4) through a serial port and is used for collecting the magnetic field data of the to-be-welded edge seam and transmitting the magnetic field data to the PLC (4), the PLC (4) controls the programmable power supply (2) to output a cur