GB1134746A - Improvements in or relating to the manufacture of moulded bodies - Google Patents

Abstract

1,134,746. Moulding tubular articles. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. 9 Dec., 1965 [14 Dec., 1964], No. 50796/64. Heading B5A. [Also in Divisions C1 and G6] Tubular articles comprising concentric zones of material having different properties are moulded from powdered material by first forming the zones in axially spaced relationship, secondly moving these into alignment and thirdly compressing and heating the whole to form the unitary article. In the embodiment shown, the mould cavity for forming the outer zone A is defined by an outer annular part 1, supported by a ring 2 on a base 3, an inner mandrel 6, and upper and lower annular plungers 4 and 7. The mould cavity for the inner zone B is defined by a reduced portion of the mandrel 6, the inner surface of plunger 7, the shoulder 9 upon the mandrel, and a third plunger 10. In operation, the parts start in the positions shown in the figure and plungers 10 and 7 are lowered slightly to lightly compact the material in cavities A and B to render the material selfsupporting. The stop 5 is then removed and pressure is applied to cap 11 to push the material in cavity B into alignment with that in cavity A (see Fig. 3, not shown). Ring 2 and cap 11 are then removed and the whole placed between the platens of a press (see Fig. 4, not shown) and heated, the composite article being pressed from above by plungers 7 and 10 and from below by plunger 4. To form a nuclear fuel pellet the material in cavity A is a mixture of graphite and a binder with a fissile oxide, nitride or carbide and in cavity B is a mixture graphite plus binder. The binder may be removed during the heating and the particles sintered together or it may be hardened, and if required subsequently carbonized.