Month in the Patent Office

Abstract

417,045. Airscrews. Grant, A. J., and Bridge, J. F., Atlas Works, Sheffield. Jan. 23, 1933, No. 2181. [Class 114.1] Blades for propellers, particularly airscrews, are made from a seamless tube of stainless steel containing 6–14 per cent nickel, 10–20 per cent chromium, up to 0·25 per cent carbon, together with 0·3–0·9 per cent titanium and with or without 0·3–1·5 per cent tungsten. The tube 10 of uniform bore is given a short tapered thickness 12 and a long tapered thickness by swaging, forging, hot rolling, drawing, or pressing in dies and with internal mandrels to the shape shown in Fig. 3. The outer walls are then machined to requisite thickness and the hub completed with flanges. The tube is then pressed in dies to an approximately elliptical form and the top end closed by welding. The hub is provided with a plug 17, Fig. 7, which has a screw threaded bore 18 to receive a supply pipe 19, whereby glycerine or other liquid under pressure is introduced into the interior whilst the blade is being finished by dies 20.