Patent ID: 7669637

Claim:
A method of manufacturing an impeller for superchargers by a lost wax casting process utilizing a die device comprising a plurality of slide supports and a plurality of slide dies each of which is freely rotatably supported by a slide support, the impeller comprising: a disk-shaped hub extending radially from a center axle; and a plurality of blades extending from the hub, which blades consist of alternately arranged full and splitter blades each having an aerodynamic curved surface, wherein a space defined by an each pair of the adjacent blades forms an undercut extending radially from the center axle, wherein the method comprises the following steps of: a) forming a sacrificial pattern having substantially the same form as the impeller, b) coating the sacrificial pattern with a refractory material and subsequently thermally removing the sacrificial pattern to form a casting mold, and c) casting the impeller with utilization of the casting mold, and wherein the step (a) of forming the sacrificial pattern is a process of injecting a sacrificial material into a cavity defined by a plurality of slide dies which are arranged radially toward the center axle, and each of which has a groove, having a bottom of the same form as the splitter blade, and a form corresponding to that of a space between an adjacent pair of the full blades; and subsequently moving the slide dies radially outwardly, while freely rotating themselves around respective motional lines of the radially outwardly moving slide dies thereby releasing them from the sacrificial pattern.