CLOSED IMPELLER

PROBLEM TO BE SOLVED: To prevent deformation of a front plate, secure strength with a simple structure while increasing rigidity of an impeller, and prevent drop of efficiency without blocking flow of fluid in an impeller. SOLUTION: The closed impeller includes a light alloy truncated cone-shaped front plate 1 and a plurality of synthetic resin blades 2 having one end surfaces of unit blade plates 21 extending in radial directions formed as blade tip surfaces 21a. Countless hyperfine recessed parts d are formed on a surface 1b of the front plate 1. Sections of the blade tip surface 21a are melted by a welding method in which resin surface temperature is raised by keeping surfaces 1b of the front plate 1 and the blade tip surfaces 21a on one end surfaces of the blades 2 in contact and giving energy from an outside under appropriate pressure. Molten resin flows into the hyperfine recessed parts d formed on the surface 1b of the front plate 1 and a welding part 50 is formed to fix the front plate 1 and the blades 2. COPYRIGHT: (C)2011,JPO&INPIT