| 摘要 |
<p>PURPOSE:To obtain a magnetic core which maintains highly precise concentricity in the outside diameter, inside diameter and groove diameter by a method wherein gates are arranged on the position separated from the configuration of manufactured article, it is injection-molded, and a gate trace is treated by plane grinding. CONSTITUTION:When injection operation is conducted, gates 4a and 4b are arranged on the position separated from the configuration of manufactured article. To be more precise, the gates 4a and 4b are provided on the inner wall of the extended section 6 which is formed by extending the inner wall 5a of the positioning hole 5 provided on the center of a magnetic core 3. The ferrite powder, which is kneaded with a binder, is injected into a mold in the above-mentioned state, and after the mixture has been held under pressure to a certain degree, it is cooled down, the mold is opened, and a disc-like magnetic core 3, on one side face 1a of which winding grooves 1 and 2 are concentrically provided, is obtained. Besides, on the above-mentioned bore 3, a spool 7 is formed on the position where the gates 4a and 4b are provided. Then, the extended section 6 is removed by conducting a plane grinding work.</p> |
