Patent ID: 6893310

Claim:
A method of adjusting a spark gap of a spark plug comprising: holding the spark plug having installed therein a center electrode and a ground electrode, the center electrode having a tip end, the ground electrode having an end with a first end surface and second end surface opposite the first end surface, the second end surface being opposed to a planar surface of the tip end of the center electrode; measuring a location of the tip end of the center electrode to determine a target distance required to move the end of the ground electrode toward the center electrode for bringing a gap between the second end surface of the ground electrode and the planar surface of the tip end of the center electrode into agreement with a target value as a function of the measured location; storing an initial location of a head of a press device, a thickness of the around electrode, and the target value in an image processing circuit; determining a distance by which the head of the press device is to be moved as a function of the initial location, the thickness, the target value and the measured location of the tip end of the center electrode; and pressing the first end surface of the ground electrode toward the planar surface of the tip end of the center electrode using the press device to move the end of the ground electrode the target distance to bring the gap between the second end surface of the ground electrode and the planar surface of the tip end of the center electrode into agreement with the target value.