Patent ID: 6602569
Filing Date: 2003-08-05
Classification: H01F,Y10S,Y10T

Abstract:
A ring shaped resin bonded magnetic member which has a relative density of not smaller than 80% and which is produced by a process comprising the steps of:(i) filling an annular cavity of a mold with a feed mixture which comprises a lubricant and a magnetic powder composite comprised of magnetic powder and a heat curable resin composition which is in a solid state at room temperature, the magnetic powder composite having a predetermined particle size range; (ii) heating only an inner peripheral surface of the annular cavity so as to transfer heat to the feed mixture through the inner peripheral surface, thereby heating the feed mixture to a temperature not lower than a softening temperature and below a curing temperature of the resin composition, and compressing the feed mixture after or during the heating, to obtain a heated and compressed feed mixture; (iii) cooling only the inner peripheral surface of the annular cavity so as to transfer heat from the heated and compressed feed mixture through the inner peripheral surface, thereby cooling the feed mixture to a temperature below the softening temperature of the resin composition so as to obtain a green compact having a ring shape; (iv) releasing and taking out the green compact from the annular cavity; and (v) heating the green compact to a temperature not lower than the curing temperature of the resin composition, to thereby form the ring shaped resin bonded magnetic member which has a relative density of not smaller than 80%.