SPARK PLUG MANUFACTURING METHOD

摘要

Provided is a method for manufacturing a spark plug which comprises a center electrode and an earth electrode spaced through a discharge gap from the center electrode, and in which at least one of the center electrode and the earth electrode includes an electrode parent material containing a base metal and a precious metal chip welded to the electrode parent material. The spark plug manufacturing method is characterized in that it comprises a laser welding step of the precious metal chip and the electrode parent material by arranging the precious metal chip at a predetermined position of the electrode parent material and by irradiating the chip and the parent material with a pulsating laser beam thereby to form the welding spots corresponding to the individual laser pulses, sequentially in the circumferential direction of the precious metal chip, and in that at least either of the laser pulses is initially increasing type laser pulses and/or finally reducing type laser pulses. At the laser irradiating time, it is possible to prevent sputters from being scattered to stick to the precious metal chip or the electrode parent material and to prevent blow holes from being formed in the individual welding spots. It is also possible to prevent cracks from being formed in the individual welding spots.