PURPOSE: To obtain a durable electrode structure providing good surface roughness and out of roundness while good shape accuracy, by forming the structure from a guide pipe, slidably inserting an electrode core wire to be supported, and a rotary supporter forced to be fitted to and held by the guide pipe while having a surface consisting of non-conductive wearing resistant material.
CONSTITUTION: An electrode core wire 1 being a machining electrode is inserted and supported slidably to a ceramics made supporting pipe 2, and the supporting pipe 2 is forced to be fitted and supported to one side of a ceramics made guide pipe 4 by a fit of about 2μ or less. While a rotary supporter 3, being forced to be fitted to and held by the other side of the guide pipe 4, is integrally formed by forcing a sheath pipe 6, consisting of non- conductive wearing resistant material of ceramics or the like, to be fitted to both sides of a metallic pipe shaft 5, and a peripheral surface of the supporter is concentrically ground with an internal diameter of the pipe 6. Accordingly, the electrode, even if it is rotated, generates no deflection with less wearing in a bearing and also in a rotary sliding surface, decreasing also the stray capacity of a wearing dust in an electric discharge machining circuit further enabling a fine hole of high out of roundness and shape accuracy to be electric discharge machined, and if the electrode is consumed, the electrode, being fed out from inside the rotary supporter, can be used being durable for long time use.
SATO TAKEO
MATSUSHITA HISATO
