Patent ID: 8092269
Filing Date: 2012-01-10
Classification: H01T

Abstract:
1. A manufacturing method of a spark plug which includes an insulator having a through-hole in an axial direction, a center electrode inserted into and fixed to a leading end side of the through-hole, a terminal electrode inserted into and fixed to a rear end side of the through-hole, a first conductive sealing material layer fixed to the center electrode in the through-hole, a second conductive sealing material layer fixed to the terminal electrode in the through-hole, and a resistor interposed between the first and second conductive sealing material layers in the through-hole and fixed to both of them, the manufacturing method comprising: a first process of inserting the center electrode into the leading end side of the through-hole, sequentially charging from the rear end side of the through-hole, predetermined amounts of a first powder material that is to be the first conductive sealing material layer, a second powder material that is to be the resistor, and a third powder material that is to be the second conductive sealing material layer to be compacted and solidified, and inserting the terminal electrode from the rear end side of the through-hole until the terminal electrode abuts the third powder material and stops; and a second process of inserting the terminal electrode to a predetermined position in a state where the insulator after finishing the first process is heated to a temperature equal to or greater than the softening temperatures of the first to third powder materials such that the first powder material becomes the first conductive sealing material layer, the second powder material becomes the resistor, and the third powder material becomes the second conductive sealing material layer, wherein a speed at which the terminal electrode is inserted is reduced from between the start and the end of the second process.