Method for manufacturing processed article, tool path calculation method, processed article, and impeller

A method for manufacturing a processed article with a tool, the tool including a cutting blade, the cutting blade having a cross-sectional surface along a tool axis of the cutting blade, an outer periphery of the cross-sectional surface being formed from arcs having different curvature radii comprising at least a first curvature radius and a second curvature radius, to machine a machined surface that includes at least one inner corner at which two adjacent machined segment surfaces meet, the method comprising:

• arranging the cutting blade to be in contact with the two machined segment surfaces simultaneously, so that two contact points are defined between the two machined segment surfaces and the cutting blade in the at least one inner corner, one of the two contact points being at the first curvature radius and another one of the two contact points being at the second curvature radius, the first curvature radius being smaller than the second curvature radius;
• and
• setting a machining pitch in a pick feed direction of the tool at the at least one inner corner to a first machining pitch for when a part of the cutting blade corresponding to the shape of the side surface of the cutting blade having the first curvature radius is a cutting point, and performing a cut along a feed direction in the two adjacent machined segment surfaces successively at the at least one inner corner so that the tool proceeds toward the at least one inner corner in one of the machined segment surfaces and away from the at least one inner corner in the other one of the machined segment surfaces, the pick feed direction being perpendicular to the feed direction of the tool.