US 6,852,264 B2 · Thermally insulated runner manifold and injection nozzle construction for plastic molding apparatus

Abstract

An improved injection molding runnerless manifold and nozzle system, method and apparatus in which the fluid plastic molding material transfer conduits, such as the manifold runner channels and cavity injection nozzle passageway, are constructed of a low thermal conductivity, non-metallic heat insulation structural material to thereby heat insulate the liquified molding material or resin, whether thermosetting or thermoplastic, while resident in the manifold runners and/or nozzle passageways. The heat transfer and other physical parameters of the conduit material and structure are such that this molding material remains at a reasonable uncured molding temperature while resident in the transfer conduit for the duration of at least one injection cycle due to the heat insulation characteristics of these fluid flow conduits of the system. Preferably the heat insulation material of which the flow conduits are constructed is a polymer material having mechanical properties adequate to permit continuous accessible usage in the foregoing method as part of a separable and clampable manifold and/or nozzle system within the mold tooling as operable in the injection molding environment.

Claims15

Dependent claims

An injection molding method for use with an injection molding machine system characterized by hot or cold runner operable for feeding a liquified plastic molding material to a mold cavity via a manifold, and for maintaining the fluidity of the manifold-resident plastic molding during closure of the injection gate, thereby enabling use of the resident molding material in the following molding cycle, said fluidity maintaining method comprising the steps of:

(a) providing a flow path for the liquified plastic molding material extending between a manifold inlet sprue, as fed by the injection machine ram of the system, and a mold cavity fed by a cavity-fill nozzle at the outlet of a runner of the system,
(b) providing said flow path as a pre-formed mold component mounted in the manifold and containing a flow conduit of high temperature resistant solid material sized to have self supporting structural integrity for flow conducting the pressurized liquified plastic molding material, and
(c) constructing said mold component containing said flow conduit of a non-metallic heat insulation material having a sufficiently low thermal conductivity to heat insulate the liquified plastic molding material resident in the conduit flow path such that this plastic molding material remains at a reasonable uncured molding temperature for the duration of at least one injection cycle of the system due to the heat insulation characteristics of the fluid flow conduit of the system.

A mold cavity filling injection nozzle for an injection molding machine comprising conduit means defining an axially extending central flow-through passageway having an outlet for allowing flow of liquefied plastic molding material into a mold cavity of a molding machine, an outlet flap, valve located inside said nozzle at said nozzle passageway outlet in aconical outlet constriction of said flow-through passageway having a flow-fill-direction convergent taper at the flow outlet end of said nozzle, said flap valve comprising a semi-resilient material having at least one very narrow slot therein communicating at an upstream end with said flow passageway and at a downstream end with the exterior of said nozzle, said slot having a length dimension axially of said nozzle greater then its width dimension transverse to the longitudinal axis of said nozzle, said slot having a thickness dimension in a direction perpendicular to the imaginary plane defined by said length and width dimensions on the order of about 0.000010 inches, said slot being thickness enlargeable by the fluid pressure exerted by liquefied plastic injection molding material when present in the said nozzle flow passageway to thereby cause flow opening action in said flap valve in response to said fluid pressure rising to a given predetermined positive value, said flap valve being operably closed by reduction of said fluid pressure to a predetermined minimum positive value or to a negative value, and

wherein said nozzle comprises an outer metal shell made from tool steel or other high strength metal alloy and provided with means for removably attaching said nozzle to said manifold, said nozzle having a flow-through interior channel communicating at its inlet end with an outlet of an associated conduit flow path runner in said manifold and at its outlet end with a passage leading to an associated mold cavity in said mold tooling, said outer shell being hollow and formed with a constant diameter bore open at the upper end of the shell and terminating and opening at its lower end at a conical interior shell surface formed by a frustoconical nose section of said shell at the downstream end of said nozzle, said shell nose having a flat end face designed to sealably seat on a corresponding flat surface provided in the associated mold tooling, said nozzle further including high temperature resistant polymer spool means received with a close fit within the inner diameter of the bore of said shell and defining said flow-through passage of said nozzle, said spool being constructed of a high temperature polymer material having low thermal conductivity, relatively high compressive strength and rigidity and relatively high wear resistance to the action of molding material in liquid state flowing therethrough under mold injection pressure.

Dependencies are inferred from the claim text.

Thermally insulated runner manifold and injection nozzle construction for plastic molding apparatus

Life of this patent

Thermally insulated runner manifold and injection nozzle construction for plastic molding apparatus

Life of this patent

Abstract

Claims15