| 摘要 |
It is an object of the invention to provide an apparatus for producing a spark plug in which thread rolling is performed in such a manner that the starting position of a threaded portion to be rolling-formed, and the joining position of a ground electrode to the tip end face of a workpiece (W) are made constant, the time period from the setting of the workpiece to the apparatus, to start of the rolling process can be shortened, the rolling efficiency can be improved, and the formation accuracy of the threaded portion starting position with respect to the ground electrode joining position can be enhanced. In the apparatus for producing a spark plug of the invention, approach driving conditions are calculated on the basis of a specified thrust feeding amount so that, while a temporal overlap occurs between a time period of feed-driving toward a rolling position (P2) of a workpiece supporting portion (11) and an approach driving time period, in a circumferential direction of a workpiece (W), a positional relationship between the starting position of the threaded portion which is rolling-formed, and the joining position of the ground electrode to the tip end face of the workpiece (W) is constant. The operation of an approach driving portion is controlled on the basis of the calculated approach driving conditions. |
