| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electromagnetic fuel injection valve with reduced magnetic resistance in an entire coil housing with an annular end wall section being thicker than a barrel section and opening a valve element high. Ž<P>SOLUTION: When manufacturing the coil housing 31, processes are sequentially performed, wherein in the first process, a plate material W1 having a thickness substantially the same with the annular end wall section 31b is prepared and a cap body W2, which includes an bottom wall W2a including the annular end wall section 31b and the barrel section 31a thinner than the bottom wall W2a, is shaped by drawing the plate material W1 with use of a die 60 and a punch 61 having a gap t<SB>1</SB>between opposite circumferential surfaces, which is set to be narrower than the thickness of the annular end wall section 31b, in the second process the bottom wall W2a of the cup body W2 is formed by punching with a through-hole W2b smaller than the inner diameter of a boss section 31c, in the third process the bottom wall W2a is softened by heat treatment, and in the forth process the boss section 31c is shaped by burring the circumference of the through-hole W2b of the softened bottom wall W2a while leaving the annular end wall section 31b. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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