Impeller of centrifugal fluid-type rotary machine and manufacturing method thereof

A method of manufacturing an impeller having an impeller plate with an outer surface and a plurality of impeller blades circumferentially spaced around and extending outwardly from said outer surface, said impeller plate having a central axis of rotation and each impeller blade having surfaces which are inclined at a selected angle to said central axis of rotation, the method comprising:

• positioning a jig rotatably indexable around a first axis of rotation inclined at an angle to a second axis, on a surface of a table lying in plane containing third and fourth axes which are perpendicular to each other and perpendicular to said second axis;
• fixing said impeller plate on said jig with said central axis of rotation of said impeller plate lying at said selected angle to said second axis;
• cutting the surfaces of one of said impeller blades using a cutting spindle with a cutting tool rotatable about an axis parallel to said second axis with said spindle being movable with respect to said table along said second third and fourth axes to form the shape of said impeller blade surfaces;
• rotating said jig to a new indexed location around said first axis to form the surfaces of a subsequent impeller blade using said cutting tool and spindle;
• cutting the surfaces of the subsequent impeller blade while moving said spindle and said table with respect to each other along said second third and fourth axes;
• and
• repeating the indexing rotation of said jig and cutting of further impeller blades until all of said impeller blades are formed on said impeller plate.