Development of Ignition Coil Dust Core

Abstract

We investigated a method for forming a high-density near-net-shape dust core for a long, high-performance ignition coil center core. In the development, the causes of deterioration of dimensional accuracy were divided into the dispersion of the amount of powder fed into the mold and the dispersion of density that occurs in the mold during molding, and the factors were analyzed. First, by sufficiently reducing the charge amount of the raw material powder, the apparent density of the powder was stabilized, and variations in the powder feed amount were suppressed. In addition, the density unevenness inside the dust core could be reduced by restructuring the upper and lower punches of the die and optimizing the stroke during compaction. Based on these results, a dust core with little density unevenness, high density, and good dimensional accuracy was realized.