A MOULD FOR THE MANUFACTURE OF A FAN HAVING A HUB AND A PLURALITY OF HELICAL BLADES EXTENDING FROM THE HUB

摘要

A mould for the manufacture of a fan having a hub and a plurality of helical blades extending from the hub, the mould having blade moulding cavities which are formed such that (a) any imaginary line extending from the rotational axis of the fan to be formed in the mould and through the blade cavity from the blade root to the blade tip intersects the rotation axis at the same angle as any other imaginary line extending in a similar manner, (b) all the imaginary lines are identical in curvature, or are all linear, and, (c) any said imaginary line can exactly replace any other said imaginary line.