Month in the Patent Office

A metallic airscrew blade is made from a billet of solid metal and one stage of the process involves axially upsetting or extruding the root portion of the blade. The extruding may be effected so as to produce a hollow or recess within the blade shank and this recess may be continued towards the root of the blade. A billet A after heating is rolled to rough blade form by rollers R and the root portion is then confined in a die 2 and an upsetting tool 4 is introduced so that the metal is forced out into the die and the point 5 of the die produces a hollow portion. The root is subjected to a series of such piercing operations until the blade and root have the form shown in section in Figs. 11 to 15.