Patent ID: 7581998
Filing Date: 2009-09-01
Classification: H01T,Y10T

Abstract:
1. A method for manufacturing a spark plug, the spark plug including: a cylindrical insulator having an axial hole penetrating said cylindrical insulator in an axial direction thereof; a center electrode inserted into said axial hole of said insulator and having a front end projecting beyond a front end surface of said insulator; a metal shell surrounding said insulator; and a ground electrode fixedly attached to said metal shell by a fixation portion and bent to form a spark discharge gap between a front end portion of said ground electrode and said front end of said center electrode; said method comprising: measuring an X-directional position of said front end of said center electrode; positioning an X-directional position of a regulation member based on said X-directional position of said front end of said center electrode measured in said center electrode position measuring step, said regulation member regulating an X-directional position of a front end surface of said ground electrode when said ground electrode is pressed and bent in a Y direction; and forming said spark discharge gap using said regulation member to regulate said X-directional position of said front end surface of said ground electrode while pressing and bending said ground electrode in said Y direction with a pressure member so as to form said spark discharge gap; wherein: said X direction designates, of directions perpendicular to a central axis of said metal shell and perpendicular to a width direction of said fixation portion of said ground electrode, a direction from said fixation portion of said ground electrode toward said central axis of said metal shell; and said Y direction designates a direction from a front end side of said internal combustion spark plug to a base side thereof along said central axis of said metal shell, wherein said regulation member positioning step comprises positioning said X-directional position of said regulation member so that said front end surface of said ground electrode will be located within a deviation range deviating from its predetermined position in said X direction with respect to said front end of said center electrode once said gap forming step has been completed, wherein said deviation range is ±0.1 mm, wherein said regulation member has a regulation abutment surface which abuts against said front end surface of said ground electrode in said gap forming step, and wherein said regulation member moves together with the pressure member when the pressure member presses said ground electrode to bend said ground electrode in the Y-direction.