ELECTRIC DISCHARGE MACHINING DEVICE

PROBLEM TO BE SOLVED: To make it possible to perform roundness improved air perforative machining without immersing the whole subject substance into a machining fluid and to shorten machining time. SOLUTION: The location of a subject substance 11 on which perforative machining is to be performed by a set of housings 14, 15 is partially sealed. An insulating seal 16 is provided between the subject substance 11 and the interior of the housing 15. An electrode 18 is inserted through the insulating seal 16 and the tip of the electrode 18 is made to come in contact with the subject substance 11. The other end of the electrode 18 is connected to an electrode rotating motor 27. A drive unit 26 ball screw and a gear are provided on the electode rotating motor 27 so that it can be moved back and forth by a servo motor. The electrode 18 is provided with a machining fluid passage 33, through which machining fluid 2 runs, and an injection nozzle 32 for injecting machining fluid 2 towards the subject substance 11. The electrode 18 rotates by the electrode rotating motor 27 and repeats forward and backward motion by the drive unit 26 by which perforative machining is performed.