MANUFACTURE OF SPARK PLUG AND DEVICE THEREFOR

摘要

PROBLEM TO BE SOLVED: To accurately and efficiently adjust a gap interval so as to improve a production yield by correcting a present adjustment control variable of a processed plug on the basis of a field proven value of an adjusted gap interval of a processed plug in the past. SOLUTION: Correction is carried out for increasing an adjustment control variable of the following processed spark plug if an adjusted gap interval measurement value g' is larger than a gap interval target value gt and for reducing an adjustment control variable for the processed spark if the adjusted gap interval measurement value g' is lower than the gap interval target value gt. That is, correction is carried out to increase the following adjustment control variable for preventing a lack of deformation if an adjusted gap interval g' of an already processed spark plug tends to rise. Contrarily, correction for reducing the following adjustment control variable is carried out if the adjusted gap interval g' tends to lower for preventing excessive deformation.