Turbo fan for range hood and range hood storing turbo fan

摘要

The spring-back state of the blade press formed from the metallic thin plate is restricted to form the blade of wing sectional shape strictly in accordance with the design. The blade is formed into the wing sectional shape having a hollow inner part with both sides fixed to the upper plate and the lower plate being released under application of the press forming of the metallic thin plate. The blade is made such that the metallic thin plate (a) having a rectangular shape as seen from its top plan view with one side being a wing width (W) size is applied with a coining work, a number of linear deformation segments in parallel with the side of the wing width (W) size are properly spaced apart along a side crossing at right angle with the side of the wing width (W) size in side-by-side relation, the direction crossing at a right angle with the side of the wing width (W) size of the metallic thin plate (a) is formed into the curved surface of predetermined curvature and then a transfer of the recovering force generated at each of the belt-like plates between the linear deformation segments is shut off at the linear deformation segments so as to restrict influence against the entire metallic thin plate (a).