| 摘要 |
It is an object of the invention to provide a method of producing a spark plug in which, in order to reduce the size of the spark plug, the diameter of a center electrode can be reduced while maintaining the heat dissipation property of the center electrode, and also such a spark plug. A columnar member 220 in which an outer skin member 21 made of a high refractory Ni alloy, and a core member 23 made of a copper alloy having a high thermal conductivity are clad, and which is columnarly extended can be configured by extrusion molding into a state where the thickness of the outer skin member 21 is substantially uniform (extrusion molding step). A flange portion 305 and a tip end portion 301 are formed in the columnar member 220 to obtain an electrode intermediate member 320 (tip end portion/flange portion forming step). In a middle trunk portion 303 of the electrode intermediate member 320, the thickness of the outer skin member 21 is maintained. The surface of the middle trunk portion 303 is cut or polished to reduce the thickness (middle trunk portion processing step), whereby the diameter of a center electrode 20 can be reduced while maintaining the outer diameter of the core member 23.
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