| 摘要 |
An object of the present invention is to improve a measurement accuracy of a deviation from a joint target position of a member to which a measuring object is joined, and to improve a measurement speed. The deviation of a ground electrode 30 from an optimal igniting position O1 is measured while a metallic shell 50 is engaged with a female thread jig 300. A distance "µ" between an axis A of the ground electrode 30 and a reference straight line LS is calculated. The distance "µ" is a vertical length from the axis A to the reference straight line LS. An angle "±" between a first straight line L1 and the reference straight line LS is calculated using the distance "µ" and a predetermined distance "²" between the axis A of the ground electrode 30 and an axis O of the metallic shell 50. |
