Method and apparatus for making spark plug

Abstract

This invention relates to a method and apparatus for making a spark plug, in particular, for making a high-performance spark plug having a center electrode having a firing end made of Pt, Ir, Rh, Pd, Re, Os, Ru or alloy thereof, with its firing end diameter of about 0.3-1.0 mm. One of the embodiments provides a method comprising the steps of: extending a metal strip from an end of the metal shell; positioning a spacer above a firing end of the center electrode; preliminarily bending the metal strip toward the spacer so as to form an arc portion in the metal strip; and then precisely forming a gap-distance between the metal strip and the firing end of the center electrode by applying a force to the metal strip. The method may further include a step of measuring the position of the firing end of the center electrode so as to determine a position for the spacer and/or a step of retrieving the spacer after bending the metal strip so that the gap-distance between the metal strip and the center electrode is adjusted to a required value by referring to a position of the preliminary bent metal strip and the position of the firing end of the center electrode. The invention also provides an apparatus for performing this method.

Dependencies are inferred from the claim text.