METHOD OF AND APPARATUS FOR THE MANUFACTURE OF HOOPS OR RINGS

摘要

1526831 Moulding a ring SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION 15 Oct 1975 [30 Oct 1974] 42114/75 Heading B5A [Also in Division B3] A method of making a hoop or ring comprises winding a wire of high modulus of elasticity on to a mandrel covered with a light metal foil, the pitch of the helical winding lying between 0À3 and 2À0 d where d=the diameter of the wire, depositing matrix material of light metal or light metal alloy on to the single helix, repeating the winding and depositing steps as required and hot pressing the blank obtained by the application of axial pressure, the outer and inner confining means used in the hot pressing being formed of materials selected to have a coefficient of expansion respectively less and greater than that of the blank to avoid applying radial stress to the blank. The matrix material, e.g. aluminium, is deposited by means of a plasma torch or as a foil and the surface may be ground after each deposition. Suggested wire is silicon carbide deposited on a tungsten core, or filaments comprising a layer of carbon, boron, silicon carbide or boron nitride or layers of several of these materials. Suitable diameters are 0À075- 0À20 mm. For the pressing step, the blank is placed between concentric annular members mounted on a base and hot pressed by an annular piston. Where for example the coefficient of expansion of the blank is 6.5 x 10-6, steel having a coefficient of expansion of 14À2 Î 10-6 can be used for the inner annular member and graphite having a coefficient of expansion of 4 Î 10-6 for the outer annular member. A reinforcing band may surround the outer member. The pressing operation for an aluminium matrix can be effected at 500‹ C. under a pressure of 40 Î 103 kPa or at 600‹ C. under a pressure of 3 x 103 kPa. The pitch of the winding in the finished ring should be not less than 0À2 of the diameter of the wire.