| 摘要 |
A spark plug for an internal combustion engine exhibiting sufficient durability and superior ignitability regardless of a mounted state and a method for manufacturing the spark plug are provided. A spark plug (1) has a center electrode (5), a ground electrode (27), and the like. A center electrode noble metal tip (31) is joined to a leading end portion of a center electrode (5), and a ground electrode noble metal tip (32) is joined to a center-electrode-side side surface (27s1) of the ground electrode (27). A distal end portion (32t) of the ground electrode noble metal tip (32) protrudes from a distal-end surface (27t) of the ground electrode (27) by 0.1 mm to 1.5 mm. A center-electrode-side side surface (32s) of the ground electrode noble metal tip (32) projects from a center-electrode-side side surface (27s1) by 0.15 mm to 0.6 mm. The ground electrode (27) has chamfered portions (27m1) to (27m4). Thickness lengths a1, a2, c1, and c2 and widthwise lengths b1, b2, d1, and d2 of the respective chamfered portions (27m1) to (27m4) achieved within a cross section perpendicular to a center axis (CL2) of the ground electrode (27) are set to 0.2 mm or more. |
