Polishing tool for narrow part, method of manufacturing polishing tool, polishing method, and method of manufacturing impeller

A method of manufacturing an impeller, the method comprising:

• fabricating an impeller including a flow path;
• and
• polishing a wall of the flow path of the impeller by sliding a polishing tool along the wall of the flow path of the impeller, the polishing tool comprising:
• an abrasive retaining layer disposed on two or more non-coplanar sides of the polishing tool and that retains, on surfaces of the two or more sides of the polishing tool, an abrasive fluid in which abrasive grains are dispersed;
• an elastic layer that is stacked on a rear side of the abrasive retaining layer;
• a first abrasive flow path that:
• is a hollow space inside a support supporting the abrasive retaining layer and the elastic layer, and
• extends from a first end to a second end in a longitudinal direction of the polishing tool;
• and
• second abrasive flow paths that extend from the first abrasive flow path to predetermined positions on a surface of the abrasive retaining layer opposite to the elastic layer, wherein, in each of the two or more sides of the polishing tool, one or more of the predetermined positions are disposed over the surface of the abrasive retaining layer,
• wherein the polishing comprises:
• pressing the abrasive fluid, retained on the surface of the abrasive retaining layer, against the wall of the impeller to polish the wall;
• and
• polishing the wall with the abrasive retaining layer interposed between the elastic layer and the wall.