Electrode for electrical discharge machining film cooling passages in an airfoil

Claim 1

An electrode adapted for installation in an electric discharge machine, said electrode including at least one longitudinally extending tooth having a longitudinally extending axis, said tooth being formed of a single piece of sheet metal and comprising, in series, a front section, a middle section and a rear section, said front section having parallel lower and upper surfaces, said upper surface lying in a first plane and having a pair of straight, parallel side edges extending in the longitudinal direction and a rear edge interconnecting said side edges; said middle section having an upper surface lying in a second plane which forms an interior obtuse angle with said first plane and an acute angle with an extension of said first plane, said upper surface of said middle section having a forward edge, said forward edge being coincident with and the same length as said rear edge of said front section and having side edges in the plane of said upper surface extending rearwardly from said forward edge on opposite sides of said longitudinally extending axis, at least one of said middle section side edges diverging from said axis; each of said side edges of said middle section having a side wall integral therewith along the length of said middle section side edge, each side wall having a surface facing outwardly away from said axis, each side wall having a straight lower edge lying in the plane of said lower surface of said front section and extending from said front section, rearwardly; and said rear section extending rearwardly from said middle section and adapted to be connected to a power source.