Heating sleeve for injection molding nozzle

A method of heating a nozzle in an injection molding apparatus comprised of:

• a manifold having a flow channel receiving a stream of injection fluid,
• a nozzle comprising a nozzle body having an upstream end, a downstream end and a flow passage having an axial length sealably communicating at the upstream end with the flow channel of the manifold for delivering the injection fluid downstream to the cavity of a mold, the nozzle body having an outer circumferential surface that reduces in cross-sectional diameter or radial length beginning from a selected upstream point to a selected downstream point along at least a portion of the axial length of the flow passage,
• a sleeve heatable to an elevated temperature, the sleeve comprising a sleeve body having a hollow bore having an upstream end, a downstream end and an axial length, the hollow bore having an inner surface complementary to the outer circumferential surface of the nozzle body such that the downstream end of the nozzle body is insertable into the upstream end of the hollow bore and further insertable downstream through the hollow bore to a point of maximum downstream travel at which the outside circumferential surface of the nozzle body engages the inside surface of the hollow bore, the engaged surfaces preventing further downstream travel of the sleeve body through the hollow bore,
• wherein the method comprises:
• inserting the downstream end of the nozzle body axially into the upstream end of the hollow bore of the sleeve,
• moving the sleeve axially upstream to surround the outer circumferential surface of the nozzle body along a predetermined axial length of the nozzle body extending up to an upstream position where the inner surface of the hollow bore mates or engages with the outer circumferential surface of the nozzle body such that the sleeve is prevented from further upstream movement.

An injection molding system comprising:

• a manifold having a flow channel receiving a stream of injection fluid,
• a nozzle comprising a nozzle body having an upstream end, a downstream end and a flow passage having an axial length sealably communicating at the upstream end with the flow channel of the manifold for delivering the injection fluid downstream to the cavity of a mold, the nozzle body having a conical outer circumferential surface that reduces in cross-sectional diameter or radial length beginning from a selected upstream point to a selected downstream point along at least a portion of the axial length of the flow passage,
• a sleeve comprised of a sleeve body having a hollow bore having an upstream end, a downstream end and an axial length, the hollow bore having a conical inner surface complementary to the outer circumferential surface of the nozzle body such that the downstream end of the nozzle body is insertable into the upstream end of the hollow bore and further insertable downstream through the hollow bore to a point of maximum downstream travel at which the outside circumferential surface of the nozzle body engages the inside surface of the hollow bore, the engaged surfaces preventing further downstream travel of the sleeve body through the hollow bore,
• a spring adapted to constantly urge the sleeve in an upstream direction with an upstream directed force relative to the nozzle body to maintain the inner surface of the sleeve body in mating contact with the outer circumferential surface of the nozzle body.