DEMAGNETIZING METHODS AND APPARATUS

摘要

Title: Demagnetizing Methods and Apparatus Demagnetizing methods and apparatus are provided in which a pipe, tube, rod, bar or other elongated part to be demagnetized is moved through the coil assembly to which pulses of current are applied to produce magentic field pulses of alternating polarity and of substantially constant durations and magnitudes with a substantially constant repetition rate, each current pulse being effective to produce by the end thereof a reversal of the magnetic field in all portions of the part positioned within the confines of the coil assembly and immediately adjacent thereto, the part being moved longitudinally through the coil assembly at a velocity sufficiently low as to effect demagnetization of all portions of the part. The duration of each current pulse is at least 50 milliseconds and most preferably on the order of 0.5 seconds and the velocity of movement is preferably less than two feet per second. The coil assembly includes two pairs of coils connected in series-aiding relation with the coils of each pair being spaced axially from each other and being adjacent the coil of the other pair. Bridge rectifier circuits are provided for energization with silicon controlled rectifiers and trigger circuits adjustable for accurate balance.