GB1227572A - - Google Patents

Abstract

1,227,572. Isostatic compaction. IFOVERKEN A.B. 28 June, 1968 [30 June, 1967 (2)], No. 30857/68. Heading B5A. In the moulding of powdered material, e.g. to a serrated profile high tension ceramic insulator, by isotactic compaction wherein a sealed yieldable vessel of rubber or plastics containing the powder is subjected to oil or water pressure of 500 to 2500 atmospheres within a pressure vessel, the vessel containing the powder is evacuated prior to compression to facilitate handling without deformation thereof, and before filling with the powder, the vessel is internally pressurized to above atmospheric to press it against the walls of a divisable mould defining the shape of the moulded article. With a non-reusable vessel which is smaller than and of a shape not corresponding to that of the insulator and which is subsequently torn from the moulded article, the vessel 13 is supported within a split mould 24 corresponding to the desired shape and provided with valved connections for vacuum 26, powder feed 27 from a container 29, and air pressure 28. The vessel 13 is inflated into contact with the mould 24, and is then filled by opening the powder feed connection and simultaneously pressurizing the container 29. After reducing pressure to atmospheric within the vessel 13, vacuum is applied thereto through a filter 36. Hollow articles or articles having passages may also be moulded by placing one or more cores in the vessel 13. The vessel may also be re-usable, if of the same shape as the moulded article, from which it is stripped by being expanded therefrom by internal air pressurization or external vacuum, preferably applied simultaneously to the vessel within a sealed container preventing excess expansion thereof.