Patent ID: 6997767
Filing Date: 2006-02-14
Classification: H01T

Abstract:
1. A method for manufacturing a spark plug comprising the steps of: providing a noble metal chip, a center electrode having a distal end face and a ground electrode having a side surface facing the distal end face of the center electrode; laser-beam-welding the noble metal chip to one of the center electrode and the ground electrode at a position corresponding to a spark discharge gap to form a noble-metal spark portion having a discharge face; the method characterized by; forming a chip joint face portion on one of the electrodes from a heat-resistant alloy predominately containing Ni or Fe and attaching the noble metal chip to the chip joint face to thereby form a chip attached assembly; providing a laser beam generator and a grated-index- type fiber optic cable having a core and an optical emissions section; and, forming a full circled laser-beam weld metal portion on the chip-attached assembly along a circumferential direction of the noble metal chip to intrude into the noble metal chip and into the chip joint face formation portion without reaching the discharge face with respect to a thickness direction by irradiating the noble metal chip and chip joint face formation portion without reaching the discharge face by irradiating the chip attached assembly with a laser beam generator and transmitting a laser beam through the core of the fiber optic cable and the emissions section while condensed by the optical emissions section.