Patent ID: 8581136

Claim:
A method of manufacturing an impeller for a centrifugal rotating machine that is approximately disk-shaped and has flow passages disposed between a plurality of blades, each of the plurality of blades being formed in a shape that curves to one side thereof in the circumferential direction along the radial direction with a first curved surface on a first side of the blade and a second curved surface on a second side of the blade, and being disposed in a radial manner from the inner circumferential side to the outer circumferential side, said method comprising: forming a first flow passage that forms a first region on the outer circumferential side within the flow passage by inserting a first electrode of a shape fitting the flow passage with an electric discharge machining method from the outer circumferential side of the disk-shaped body having an outer shape of an impeller; and forming a second flow passage that forms a second region on the inner circumferential side within the flow passage from the inner circumferential side of the disk-shaped body, wherein in said forming the first flow passage, using the first electrode which has a first curved face with a curve that corresponds to the second curved surface of the blade and a second curved face with a curve that corresponds to the first curved surface of the blade, a curvature radius of the second curved surface of the blade is more than or equal to a curvature radius of the first curved face of the first electrode, a curvature radius of the second curved face of the first electrode is more than or equal to a curvature radius of the first curved surface of the blade, and the first electrode is capable of being inserted into the first flow passage so as to be spaced from the first flow passage in the circumferential direction, at the first region.