METHOD OF PRODUCING POWDER MAGNETIC CORE, AND POWDER MAGNETIC CORE

PROBLEM TO BE SOLVED: To reduce burrs and to modify the outer shape in a powder magnetic core obtained by subjecting iron based magnetic powder coated with an insulating film to compacting. SOLUTION: The fact that a green compact 110 obtained by coating each inside face of dies 100, 102, 104 for compacting with a higher fatty acid based lubricant 106 and covering the same with an insulating film, and performing compacting (stages (a) to (d)) to the iron based magnetic powder 108 under high pressure can be subjected to plastic working has been found. Then, using upper and lower dies 120, 122 for shape modification whose inside shapes are bulged in accordance with the parts at which burrs 112 are produced in the green compact 110, plastic working (stages (f), (g)) is performed by compacting for shape modification. In the powder magnetic core 130 subjected to the shape modification, the burrs are removed, and the one having roundness can be obtained. It is also possible that preliminary annealing is performed before the shape modification stage. COPYRIGHT: (C)2005,JPO&NCIPI