Formation sheet metal blade helicopter e.g. - involves stretching blank whilst applying to mandrel with final reduced edge radii obtained by folding

摘要

The process may be used to form blades for wind-generators or helicopters from sheet metal. It involves subjecting a blank (17) to a transverse drawing operation whilst applying it to a mandrel (22) forming a central curved leading edge. The radius (r') of the mandrel is greater than that finally required. The angle of the mandrel opening may also exceed that of the finished work in respect of both the leading and trailing edges, the mandrel also having significant extra length (L'). The trailing edge may have a face (26) normal to the longitudinal axis (P').