An electric discharge machining apparatus includes a tool electrode that performs electric discharge machining to a workpiece, a housing in which the tool electrode is inserted, a compressed gas supplying device for supplying compressed gas into a mist generating region which is provided between an inner wall of the housing and the tool electrode, a first flow path through which the compressed gas flows and connecting the compressed gas supplying device with the mist generating region, a pressurized working fluid supplying device for supplying pressurized working fluid into the mist generating region, and a second flow path through which the pressurized working fluid flows and connecting the pressurized working fluid supplying device with the mist generating region.

EDM assemblies mount on a machining surface and discharge rotating sub-electrodes against the surface. The sub-electrodes can also revolve about another shared axis while discharging. Rotation and revolution may be achieved with planetary gears fixed with the sub-electrodes and meshing with a stationary sun gear. Several sub-electrodes can be used in a single assembly. Downward movement of the sub-electrodes from a central shaft on the mount allows several inches of the surface to be machined. Assemblies are usable in a nuclear reactor during a maintenance period to machine a hole for a replacement manway cover underwater in the flooded reactor. The differing rotational movements and vertical movement can be independently controlled with separate motors in the assembly. Power and controls may be provided remotely through an underwater connection.

EDM assemblies mount on a machining surface and discharge rotating sub-electrodes against the surface. The sub-electrodes can also revolve about another shared axis while discharging. Rotation and revolution may be achieved with planetary gears fixed with the sub-electrodes and meshing with a stationary sun gear. Several sub-electrodes can be used in a single assembly. Downward movement of the sub-electrodes from a central shaft on the mount allows several inches of the surface to be machined. Assemblies are usable in a nuclear reactor during a maintenance period to machine a hole for a replacement manway cover underwater in the flooded reactor. The differing rotational movements and vertical movement can be independently controlled with separate motors in the assembly. Power and controls may be provided remotely through an underwater connection.

To provide a turbine blade, a manufacturing method for a turbine blade, and a gas turbine. In the turbine blade including a cooling passage provided along a blade height direction, the cooling passage includes: a first cooling hole including one end opening toward a front end, and having an inner diameter that is constant along the blade height direction; and a second cooling hole including one end communicating with the other end of the first cooling hole without a level difference, and having an inner diameter that is increased toward a base end. A length from the one end of the first cooling hole to a position where the first cooling hole and the second cooling hole are communicated with is 40% to 60% of a length from the one end of the first cooling hole to a gas path surface on the base end.

An electrical-discharge machining tool comprising a ground electrode, a moveable and activatable assistive electrode and a cutting electrode, a first conduit for supplying a dielectric and a second conduit for flushing dielectric material, wherein when used on a dielectric layer on a substrate the assistive electrode is activated and positioned substantially between the ground electrode and the cutting electrode.

A manufacturing method is provided. During this method, a preform component is provided for a turbine engine. The preform component includes a substrate. A preform meter section and a preform diffuser section are formed in the substrate. An internal coating is applied to at least the preform meter section to provide a meter section of a cooling aperture. External coating material is applied over the substrate. The applying of the external coating material forms an external coating over the substrate. The applying of the external coating also builds up the external coating material within the preform diffuser section to form a diffuser section of the cooling aperture.

A method for accurately producing the drilled hole in a wall of a component fabricated by investment casting process, such as for use in a blade or steam turbine includes the following steps. The 3D data of actual component is obtained from the measurements or from the numerical simulation. The actual model and the ideal model are aligned and compared, a series of cutting planes are given to establish a series of 2D cross-sections of the actual and ideal models after registration. Each cross-section is dispersed into discrete points, the distance between each corresponding points are calculated and formed into 2D displacement. The accurate parametric model consisting of the depth, hole center, and the nominal vector is obtained on the basis of considering the deviations in geometrical and positional values. The drilled hole is then produced according to the corrected parametric drilled-hole geometrical and positional value.

This fine hole electrical discharge machine applies voltage between a fine hole machining electrode and a workpiece to cause discharge, and machines a fine hole in the workpiece by using energy of the discharge. The fine hole electrical discharge machine comprises: a bendable guide tube having a hollow portion through which the electrode is inserted; and a tube holder that supports the leading end of the guide tube and allows the leading end of the guide tube to be inclined at a desired angle. Thus, even when the workpiece has a complicated shape, like a blisk, having a large number of turbine blades arranged in the circumferential direction, a fine hole can be machined by accurately positioning the electrode so as to orient the electrode toward a target machining point on a surface of the workpiece without involving interference with the workpiece.

This fine hole electrical discharge machine applies voltage between a fine hole machining electrode and a workpiece to cause discharge, and machines a fine hole in the workpiece by using energy of the discharge. The fine hole electrical discharge machine comprises: a bendable guide tube having a hollow portion through which the electrode is inserted; and a tube holder that supports the leading end of the guide tube and allows the leading end of the guide tube to be inclined at a desired angle. Thus, even when the workpiece has a complicated shape, like a blisk, having a large number of turbine blades arranged in the circumferential direction, a fine hole can be machined by accurately positioning the electrode so as to orient the electrode toward a target machining point on a surface of the workpiece without involving interference with the workpiece.

Disclosed techniques include creating a pressure differential within an interior of a dual-wall component relative to pressure at an exterior of the dual-wall component, fabricating a hole in a first wall of the dual-wall component, while fabricating the hole in the first wall of the dual-wall component, acoustically monitoring the hole fabrication, while acoustically monitoring the hole fabrication, detecting breakthrough of the first wall of the dual-wall component based on an acoustic signal due to gas passing through the fabricated hole, and based on the acoustic signal, ceasing the fabrication of the hole.