Ngk Spark Plug Company, Limited

Akikazu Taido

Tomoaki Kato

Akira Suzuki

Kazuyoshi Torii

Yuichi Nakano

There is provided manufacturing method of a spark plug that includes a center electrode and a ground electrode with a discharge gap left therebetween. At least one of the center electrode and the ground electrode has an electrode body containing a base metal and a noble metal tip welded to the electrode body. The spark plug manufacturing method includes 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.

Spark plug manufacturing method

There are provided a spark plug in which a plating film applied to a ground electrode can be relatively easily removed, without cost increase, to prevent deterioration in ignition performance, and a process for producing the spark plug. A spark plughas a metal shell, a ground electrodemade of a Ni alloy and a Ni plating layercontaining Ni as a main component and applied to surfaces of at least a rear end portion of the ground electrodeand of the metal shell. A Ni plating filmapplied to a center-electrode-side part of a portion of the ground electrodeto be bent has been irradiated with a laser beam or the like, thereby forming a molten layerin which metal materials of the Ni plating filmand the ground electrodeare molten together on the center-electrode-side part of the portion of the ground electrodeto be bent. The Ni plating layeris formed on a part of the ground electrodeother than the part irradiated with the laser beam.

Spark plug and process for producing same

A method for manufacturing a spark plug is a method for manufacturing the spark plug having an electrode base member and a noble metal tip welded thereto by means of a laser or an electrode base member, a tip base member joined thereto, and a noble metal tip welded to the tip bases material by means of a laser, and the method includes a laser welding process of welding the electrode base member or the tip base member to the noble metal tip by means of a laser and through use of a laser beam whose BBP value assumes 25 mm&#xb7;mrad (a radius&#xb7;a half angle) or less at a time point when a laser beam enters a transfer optical system for guiding the laser beam to areas to be welded where laser welding is to be performed.

Method for manufacturing spark plug

There is provided a method for producing a spark plug in which welding strength between a noble metal tip and an electrode joined by laser welding can be restrained from becoming weak. A noble metal tip () to be joined to a center electrode () or ground electrode of a spark plug to form a spark discharge gap is resistance-welded to each electrode containing no noble metal and then laser-welded. In the noble metal tip () exposed under a severe environment involving spark discharge, a molten portion () formed in such a manner that a portion of the noble metal tip () and a portion of the electrode are melted by laser welding and a non-molten portion () on the noble metal tip () side are apt to be peeled from each other in a boundary surface () between the molten portion () and the non-molten portion (). The noble metal content in the molten portion () however becomes higher because a flange portion is formed in a bottom portion by pressing force applied on the noble metal tip () at the time of resistance welding and then irradiated with a laser beam. Accordingly, peeling can be prevented from occurring in the boundary surface ().

Growing community of inventors

Nagoya, Japan

Akikazu Taido