| 摘要 |
PURPOSE:To reduce the number of defects and to improve a magnetic characteristic by forming a recessed part in the length direction on the surface at the side where a front core member faces a back core, forming a stepped groove with the prescribed length in said recessed part and executing bonding and grinding afterwards. CONSTITUTION:A bobbin 2 wounded by a coil 1 is loaded on the back core 3, and the recessed part 61 is formed in the length direction on one surface of the front core member 6, whereby two end surfaces capable of being jointed are formed on two end surface in parallel with each other on the back core 3. In the recessed part 61, the stepped groove made of the 1st groove 62 in a width L and the 2nd groove 63 in a width l is formed, where L>l. A subcore 7 made of plate-like cores with the same width and the same length is fitted in the 2nd groove 63, and the height of the subcore 7 is about the sum of the depth of the 1st groove 62 and that of the 2nd groove 63. Molten glass is poured in the recessed part 61 and the groove 62, and bending is made so as to bury the subcore 7. Afterwards the outside of the front core member 6 is ground up to the depth, as alternate long and short dash lines show, to produce a front core 60.
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