| 摘要 |
<p>An object is to enable a burr-free surface of a tip to be welded to a ground electrode more reliably, to thereby realize an excellent joint strength. Means for Solution A spark plug (1) includes a center electrode (5), a ground electrode (27), and a ground-electrode-side tip (32) joined to the ground electrode (27) through its joining surface (32B). A process of manufacturing the spark plug (1) includes a tip forming step and a tip joining step of resistance-welding the ground-electrode-side tip (32) to the ground electrode (27). The tip forming step includes a wire rod forming step of forming a wire rod (WR) having a reference surface (BS), and a wire rod cutting step of cutting the wire rod (WR) by moving a cutting blade CE from one edge of the reference surface (BS) with respect to the width direction thereof toward the other edge of the reference surface (BS) with respect to the width direction, to thereby obtain the ground-electrode-side tip (32). In the tip joining step, at least a portion of the reference surface (BS) of the ground-electrode-side tip (32) is joined to the ground electrode (27), whereby that portion becomes the joining surface (32B).</p> |
