| 摘要 |
<p>In apparatus for extruding a covering on to an advancing core and for continuously treating the covering with a fluid medium at super-atmospheric pressure, intended for use where the covering is applied to the core by a "float-down" process, sealing means associated with the core tube of the extrusion machine comprises at least one inflatable collar which will surround a core advancing through the bore of the core tube. A radially inner layer of heat-resistant material of a low coefficient of friction is positioned between the collar and the advancing core. The arrangement is such that when the inflatable collar is at least partially inflated it is constrained to effect a circumferential compressive force radially inward on the inner layer of heat-resistant material to cause the collar andd the inner layer to effect a substantially fluid-tight seal between the core tube and the advancing core. Preferably, the inflatable collar comprises a sleeve mounted on the radially inner surface of a tubular housing connected to the upstream end of the core tube, the sleeve being sealed at each of its ends to one of a pair of apertured barrier walls and overlying a passage in the circumferential wall of the housing through which fluid can be introduced to inflate the sleeve.</p> |
