Apparatus for extruding a covering on to a cable core

Claim 2

Apparatus for extruding a covering on to an advancing core and for continuously treating the covering with a fluid medium at super-atmospheric pressure, which apparatus comprises an extrusion machine comprising a core tube extending through the extrusion machine, and an annular extrusion orifice at the outlet of the extrusion machine defined by an outer die and an inner die or point mounted on the downstream end of the core tube; sealing means associated with the core tube which permits passage of the core therethrough; a treatment chamber which is hermetically sealed to the outlet end of the extrusion machine and through which the covered core emerging from the extrusion orifice is adapted to pass; means for introducing a fluid medium under super-atmospheric pressure into the treatment chamber; and means for injecting a fluid under pressure to the interior of the core tube, wherein the sealing means comprises at least one inflatable collar associated with the core tube in such a way that it will surround a core advancing through the bore of the core tube; and, positioned between the collar and said advancing core, a radially inner layer of a heat-resistant material of a low coefficient of friction; the arrangement being such that when the inflatable collar is at least partially inflated it will be constrained to effect a circumferential compressive force radially inward on the inner layer of heat-resistant material to cause the collar and the inner layer to effect a substantially fluid-tight seal between the core tube and the advancing core.

Claim 3

Apparatus for extruding a covering on to an advancing core and for continuously treating the covering with a fluid medium at super-atmospheric pressure, which apparatus comprises an extrusion machine comprising a core tube extending through the extrusion machine, and an annular extrusion orifice defined by an outer die and an inner die or point mounted on the downstream end of the core tube; sealing means associated with the core tube which permits passage of the core therethrough; a treatment chamber which is hermetically sealed to the outlet end of the extrusion machine and through which the covered core emerging from the extrusion orifice is adapted to pass; means for introducing a fluid medium under super-atmospheric pressure into the treatment chamber; and means for injecting a fluid under pressure to the interior of the core tube, wherein the sealing means comprises a tubular housing connected to the upstream end of the core tube; at least one inflatable collar fitted in the bore of the housing in such a way that it will surround a core advancing through the bore of the housing; and, positioned between the collar and said advancing core, a radially inner layer of a heat-resistant material of a low coefficient of friction; the arrangement being such that when the inflatable collar is at least partially inflated it will be constrained to effect a circumferential compressive force radially inward on the inner layer of heat-resistant material to cause the collar and the inner layer to effect a substantially fluid-tight seal between the core tube and the advancing core.

Claim 4

Apparatus for extruding a covering on to an advancing core and for continuously treating the covering with a fluid medium at super-atmospheric pressure, which apparatus comprises an extrusion machine comprising a core tube extending through the extrusion machine, and an annular extrusion orifice defined by an outer die and an inner die or point mounted on the downstream end of the core tube; sealing means associated with the core tube which permits passage of the core therethrough; a treatment chamber which is hermetically sealed to the outlet end of the extrusion machine and through which the covered core emerging from the extrusion orifice is adapted to pass; means for introducing a fluid medium under super-atmospheric pressure into the treatment chamber; and means for injecting a fluid under pressure to the interior of the core tube, wherein the sealing means comprises a tubular housing connected to the upstream end of the core tube; at least one inflatable collar fitted in the bore of the housing in such a way that it will surround a core advancing through the bore of the housing; and, positioned between the collar and said advancing core, a radially inner layer of a heat-resistant material of a low coefficient of friction; the arrangement being such that when the inflatable collar is at least partially inflated it will be constrained to effect a circumferential compressive force radially inward on the inner layer of heat-resistant material to cause the collar and the inner layer to effect a substantially fluid-tight seal between the core tube and the advancing core.

Claim 5

Apparatus as claimed in claim 2, wherein the tubular housing has, at each of its ends, an apertured barrier wall through which an advancing core can pass and which serves to restrain the inflatable collar and the inner layer of heat-resistant material against substantial movement in a direction substantially parallel to the axis of the bore.

Claim 6

Apparatus as claimed in claim 2, wherein the tubular housing has a circumferential wall opening into which is a passage for the introduction of inflating fluid and has, at each of its ends, an apertured barrier wall through which an advancing core can pass, and wherein the inflatable collar comprises a sleeve of heat-resistant, elastomeric fluid-impermeable material Mounted on the radially inner surface of said circumferential wall to overlie the opening of said passage and sealed at each of its ends to one of said two apertured barrier walls, the apertured barrier walls serving to restrain the sleeve and the inner layer of heat-resistant material against substantial movement in a direction substantially parallel to the axis of the bore.

Claim 7

Apparatus as claimed in claim 1, wherein the inner layer of heat-resistant material is separate from the inflatable collar and comprises a plurality of turns of an elongate flexible member of the heat-resistant material.

Claim 8

Apparatus as claimed in claim 5, wherein the elongate flexible member is in the form of a stranded rope.

Claim 9

Apparatus as claimed in claim 5, wherein the heat-resistant material of the elongate flexible member is a fluorocarbon polymer or copolymer.