Method for manufacturing coil-embedded dust core and coil-embedded dust core
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Abstract
It is an object to provide a method for manufacturing a coil-embedded dust core with a small variation in inductance value with efficiency and the like. A step (a) of charging soft magnetic metal powder including an insulating material, composing a green body 10, so as to cover a coil 1, and a step (b) of compacting the soft magnetic metal powder covering the coil 1 in an axial direction of the coil 1 are included, and in the step (b), the soft magnetic metal powder is compacted while an amount of the soft metal powder charged into the part corresponding to the winding section is kept smaller than an amount of the soft magnetic metal powder charged into the other part that are not corresponding to the winding section, with an upper surface or a lower surface of the winding section as a reference. Thereby, a coil-embedded dust core with entirely uniform density can be obtained, and according to the coil-embedded dust core with entirely uniform density, a variation in inductance value is reduced and it becomes possible to obtain a predetermined inductance value with stability.
11 Citations
16 Claims
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1-4. -4. (canceled)
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5. A method for manufacturing a coil-embedded dust core in which an air-core coil is embedded in a green body with use of a die machine comprising a upper die set including an upper die and a top punch ascending and descending inside said upper die, and a lower die set including a lower die and a bottom punch ascending and descending inside said lower die, comprising:
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(a) charging soft magnetic metal powder including an insulation material, composing said green body, into a cavity of said lower die equipped with a tubular member, which has a top portion in substantially the same shape as the plane shape of said air-core coil, in said bottom punch to be ascendable and descendable;
(b) placing said air-core coil concentrically with said tubular member in a state in which it ascends to a predetermined position, inside the cavity of said lower die with said soft magnetic metal powder being charged therein;
(c) lowering said upper die to said lower die, and further charging said soft magnetic metal powder into a cavity of said upper die so as to cover said air-core coil; and
(d) compacting said soft magnetic metal powder in an axial direction of said air-core coil by relatively lowering said top punch with respect to said bottom punch. - View Dependent Claims (6, 7, 13, 14, 15, 16)
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8-12. -12. (canceled)
Specification