Abstract: Some implementations of the described invention provide an improved centerless grinding apparatus in which grinding is efficiently operated by reducing the idle time of the grinding wheel. While the described apparatus can comprise any suitable feature, in some cases, it includes a first regulating wheel and a second regulating wheel are axially aligned side by side. In some cases, a first grinding area is provided between the first regulating wheel and a first blade. In some cases, a second grinding area is provided between the second regulating wheel and a second blade. Additionally, in some cases, a grinding wheel is mounted on a grinding wheel Z-slide to be moved reciprocatively between the first grinding area and the second grinding area. In this way, grinding is efficiently operated by reducing the idle time of the grinding wheel.

Abstract: A set of split bodies for forming a synthetic-resin blower fan through a hollow-article injection molding process, wherein the blower fan integrally includes a circular base, a cover portion having an air inlet opening at the center thereof, and a plurality of blades. The set of split bodies comprise a first split body including the circular base and a plurality of blade members, and a second split body defining the inner surface of the cover portion and having an outer surface on the opposite side of the first split body. The outer surface of the second split body is formed with a plurality of reservoirs each extending radially in alignment with the corresponding blade member of the first split body to define spaces to be filled with molten synthetic resin in a state where the first and second split bodies are assembled together.