GB1328688A - Apparatus for pressing of clay pipe using an elastomeric mandrel - Google Patents

Abstract

1328688 Moulding clay pipes ROBINSON CLAY PRODUCT CO 27 Oct 1970 51029/70 Heading B5A A green clay pipe is moulded from clay powder 13, by the compression thereof against a surrounding cylindrical housing 10, by an elastomeric sleeve 17 expanded by pressure fluid e.g. at 6,000 p.s.i. admitted to and relieved from the interior of the sleeve, through passages 24, 25, in a rod 14, and passages 28 through a sleeve 15. The sleeve 17 is sealingly clamped at its ends to the rod 14 between inner and outer members 16, 18 urged together by nuts 39. The housing 10 is inset at 10a into a base 11, and the members 18 are clamped against the base 11 by a cap 36, engaging under projections 37 from the housing, which also supports an upper moulding cavity seal 35. A rod passage 21 is used as a vent after withdrawal of pressure fluid through passage 24. The moulded pipe is ejected by a ring 30 urged upwardly by power means actuated push-rods 32. In the Fig. 1 embodiment, the housing 10 is lined by a thin shell 12 which engages the housing 10 at an upwardly increasing taper facilitating ejection thereof with the moulded pipe, release of the shell 12 from the moulded pipe being facilitated by the shell 12 either comprising two semi-cylindrical sections, or having a single longitudinally extending slit which is widenable under the natural spring tension of the sleeve 12. In an alternative embodiment, Figs. 3 and 4 (not printed) the moulding cavity is vented through an upper closure ring, and the housing (10) is lined with a sleeve (12<SP>1</SP>) of polyamide, magnesium alloy or bronze, which is slightly inwardly compressed during moulding by application of fluid pressure to the exterior thereof, to facilitate release of the moulded pipe therefrom when the sleeve expands when the exterior fluid pressure thereon is relieved. Alternatively, release of the moulded pipe from the sleeve (12<SP>1</SP>) may be facilitated by thermal expansion of the sleeve (12<SP>1</SP>), either by passage of an electric current therethrough e.g. if the sleeve (12<SP>1</SP>) is of aluminium or aluminium alloy, or by steam heating of the exterior thereof, Fig. 1A (not printed), with cooling by refrigerated water for the following moulding operation. The clay particles may be lubricated by up to 8% water, or 1 to 4% kerosene.