MANUFACTURING METHOD OF SPARK PLUG

• Main Author: KAWANO HAJIME
• Format: Patent
• Language: English; Japanese
• Published: 21.01.2021
• Subjects: BASIC ELECTRIC ELEMENTS; CORONA DEVICES; ELECTRICITY; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARK GAPS; SPARKING PLUGS

To provide a manufacturing method of a spark plug in which the position accuracy of a male thread with respect to a ground electrode is increased.SOLUTION: In a manufacturing method of a spark plug that has a metallic shell including a cylindrical shaft and a flange projecting radially outward from a rear end of the shaft and in which a male thread is formed on an outer peripheral surface of the shaft, a center electrode that is insulatively held at a tip-side center of the shaft, and a ground electrode that is connected to the shaft and faces the center electrode via a spark gap, the manufacturing method compromises a deformation step in which in a state where a work having the shaft and the flange connected to the ground electrode and functioning as the metallic shell is halted, a die in a state of not rotating is urged against the outer peripheral surface of the shaft of the work to deform the shaft with the die, and a processing step in which the die is rotated to form the male thread on the shaft after the deformation step.SELECTED DRAWING: Figure 2 【課題】接地電極に対するおねじの位置精度を向上できるスパークプラグの製造方法を提供すること。【解決手段】円筒状の軸部と、軸部の後端から径方向の外側へ張り出す鍔部と、を備え、軸部の外周面におねじが形成された主体金具と、軸部の先端側の中心に絶縁保持される中心電極と、軸部に接続されると共に中心電極との間で火花ギャップを介して対向する接地電極と、を備えるスパークプラグの製造方法において、接地電極が接続された軸部と鍔部とを備えるワークであって主体金具となるワークを停止させた状態で、無回転状態のダイスをワークの軸部の外周面に押し付け、ダイスで軸部を変形させる変形工程と、変形工程の後、ダイスを回転させて軸部におねじを形成する加工工程と、を備える。【選択図】図２