Patent ID: 6592418
Filing Date: 2003-07-15
Classification: H01T

Abstract:
A method for manufacturing a spark plug comprising a center electrode disposed within an insulator, a metallic shell disposed outside the insulator, and a ground electrode, one end of the ground electrode being joined to an end face of the metallic shell, an opposite end portion of the ground electrode being bent such that a side surface of the opposite end portion faces an end face of the center electrode so as to form a spark gap between the side surface and the end face, said method comprising:a photographing step for photographing the spark gap by use of photographing means; a gap calculation step for determining a gap which comprises defining a reference point on the basis of image information obtained from said photographing step, defining a plurality of measurement lines passing through the reference point, measuring along each of the measurement lines a distance between a ground electrode spark gap definition portion of the ground electrode facing the spark gap and a center electrode spark gap definition portion of the center electrode facing the spark gap, and determining a gap on the basis of the measured distance; and an after-treatment step for performing a predetermined after-treatment on the basis of the calculated gap.