Drill rod demagnetizing device and method

The invention relates to a drill rod demagnetizing device and method, and belongs to the technical field of coal mine equipment. The demagnetizing device comprises a transmission mechanism, two demagnetizing coils connected with the transmission mechanism and synchronously and relatively moving at the same speed, and a controller electrically connected with the transmission mechanism and the demagnetizing coils, wherein the centers of the two demagnetizing coils are located on the same horizontal line, a drill rod is horizontally inserted into the inner cavity of each demagnetizing coil, and the two demagnetizing coils are symmetrical relative to the middle of the drill rod. According to the invention, the two demagnetizing coils symmetrically arranged relative to the middle of the drill rod relatively move at a constant speed along the length direction of the drill rod to demagnetize the drill rod in both directions while change the polar direction of the residual magnetism on the drill rod, the polar direct