Patent ID: 8633418

Claim:
A manufacturing method of a spark plug, the spark plug having a center electrode and a ground electrode with a discharge gap left therebetween, at least one of the center electrode and the ground electrode having an electrode body containing a base metal and a noble metal tip welded to the electrode body, the manufacturing method comprising a laser welding step for welding the noble metal tip and the electrode body by placing the noble metal tip at a given position on the electrode body, irradiating a pulsed laser onto the noble metal tip and the electrode body and thereby sequentially forming welding spots corresponding to pulses of the laser in a circumferential direction of the noble metal tip, wherein at least one of the laser pulses is an initially increasing type laser pulse having a laser intensity waveform in which a laser intensity increases with time during a predetermined initial period from a pulse start time and remains at a constant laser intensity level during a predetermined middle period subsequent to the initial period, and wherein the laser intensity of the initially increasing type laser pulse starts from a given level, which is one-third to one-half of the laser intensity level of the middle period, and gradually increases with time during the initial period.