SPARK PLUG MANUFACTURING METHOD, AND SPARK PLUG

摘要

Provided is a method for manufacturing a spark plug including a cylindrical main metal fitting, a cylindrical insulator held in the main metal fitting, a center electrode held in the insulator and extending in the axial direction, and an earth electrode having a base end portion to be fixed on the main metal fitting and a leading end portion equipped with a protruding portion confronting the leading end portion of the center electrode through a clearance, and made to have a substantially equal thickness other than the portion having the protruding portion. The spark plug manufacturing method is characterized by comprising a pressing step of pressing the entirety of an earth electrode material for forming the earth electrode, thereby to form the protruding portion at the leading end portion of the earth electrode material, and a welding step of welding the base end portion of the earth electrode material to the main metal fitting.