EP4673294A1

EP4673294A1 - Molds, mold assemblies and stack components

Info

Publication number: EP4673294A1
Application number: EP23924501.2A
Authority: EP
Inventors: Ralf Walter Fisch; Sven Kmoch; Arnold Heinz MAI; Yves Gilles BENJAMIN
Original assignee: Husky Injection Molding Systems Luxembourg IP Development SARL
Current assignee: Husky Injection Molding Systems Luxembourg IP Development SARL
Priority date: 2023-02-27
Filing date: 2023-12-19
Publication date: 2026-01-07
Also published as: WO2024178490A1; CN120752127A

Abstract

A mold stack (104, 204, 304, 404, 504) for molding a preform (P) that includes a cavity insert (131, 231, 331, 431, 531), a split mold insert (123, 223, 323, 423, 523) and an interface (140, 240, 340, 440, 540) therebetween. The cavity insert has a molding surface (135, 235, 335, 435, 535) describing part of a body of the preform. The split mold insert has a molding surface (124, 224, 324, 424, 524) describing part of the body and a radial flange of the preform. The interface includes a non-mating portion (141, 241, 341, 441, 541) that surrounds and extends from the molding surfaces and a mating portion (142, 242, 342, 442, 542) that surrounds the non-mating portion. The non-mating portion describes a gap (G) between the cavity and split mold inserts when a clamp force is transmitted across the mating portion when the mold stack is in a molding configuration.

Description

MOLDS, MOLD ASSEMBLIES AND STACK COMPONENTS

FIELD OF THE INVENTION

This invention relates generally to molding apparatus and associated methods. More specifically, although not exclusively, this invention relates to mold stacks and components thereof, mold assemblies, molds, molding systems for molding preforms and other articles, for example tubular articles, and to associated methods.

BACKGROUND OF THE INVENTION

Molding is a process by virtue of which a molded article can be formed from molding material, such as a plastics material, by using a molding system, such as an injection molding system or a compression molding system. Various molded articles can be formed by using such molding processes including, for example, preforms which can be formed from polyethylene terephthalate (PET) material. Such preforms are capable of being subsequently blown into a container, for example a beverage container, bottle, can or the like.

As an illustration, injection molding of preforms involves heating PET material (or other suitable molding material for that matter) to a homogeneous molten state and injecting, under pressure, the so- melted material into a molding cavity defined, at least in part, by a female cavity piece and a male core piece. Typically, the female cavity piece is mounted to a cavity plate and the male core piece is mounted to a core plate of a mold. The cavity plate and the core plate are urged together and are held together by clamp force, the clamp force being sufficient to keep the cavity and the core pieces together against the pressure of the injected material. The molding cavity has a shape that substantially corresponds to a final cold-state shape of the molded article to be molded. The so-injected material is then cooled to a temperature sufficient to enable removal of the so-formed molded article from the molding cavity. When cooled, the molded article shrinks inside of the molding cavity and, as such, when the cavity and core plates are urged apart, the molded article tends to remain associated with the core piece.

Accordingly, by urging the core plate away from the cavity plate, the molded article can be subsequently demolded by ejecting it off the core piece. Ejection structures are known to assist in removing the molded articles from the core halves. Examples of the ejection structures include stripper plates, stripper rings and neck rings, ejector pins, etc.

When dealing with molding a preform that is capable of being subsequently blown into a beverage container, one consideration that needs to be addressed is forming a so-called "neck region". Typically and as an example, the neck region includes (i) engaging features, such as threads (or other suitable structure), for accepting and retaining a closure assembly (ex. a bottle cap), and (ii) an anti-pilferage assembly to cooperate, for example, with the closure assembly to indicate whether the end product (i.e. the beverage container that has been filled with a beverage and shipped to a store) has been tampered with in any way. The neck region may comprise other additional elements used for various purposes, such as to cooperate with parts of the molding system (ex. a support ledge, etc.). As is appreciated in the art, the neck region cannot be formed easily by using the cavity and core halves. Normally, split mold inserts (sometimes referred to by those skilled in the art as "neck ring") are used to form the neck region.

A typical molding insert stack assembly that can be arranged (in use) within a molding machine includes a split mold insert pair that, together with a mold cavity insert, a gate insert and a core insert, defines a molding cavity. Molding material can be injected into the molding cavity from a source of molding material via a receptacle or port in the gate insert to form a molded article. In order to facilitate forming of the neck region of the molded article and subsequent removal of the molded article therefrom, the split mold insert pair comprises a pair of complementary split mold inserts that are mounted on adjacent slides of a slide pair. The slide pair is slidably mounted on a top surface of a stripper plate.

As commonly known, the stripper plate is configured to be movable relative to the cavity insert and the core insert, when the mold is arranged in an open configuration. The slide pair, and the complementary split mold inserts mounted thereon, can be driven laterally, via a cam arrangement or any other suitable known means, for the release of the molded article from the molding cavity. One of the functions performed by the split mold insert pair is to assist in ejecting the molded article off the core insert by "sliding" the molded article off the core insert, typically into a cooling tube mounted to a post mold cooling unit of a downstream handling device. During de-molding, the stripper plate and core plate remain together when the cavity and core plates are urged apart. The interface between the split mold inserts and the features of the neck region help to retain the molded article on the core insert, which can be crucial with certain preform designs. Mold stacks have in the past been designed such that part of the support ledge is described by the split mold inserts, with the other part described by the cavity inserts. Whilst this design approach provides benefits that are appreciated by those skilled in the art, it can result in so-called thread pull (distortion of the threads) with certain preform designs. As such, encapsulating the support ledge within the split mold insert is beneficial for avoiding such defects.

However, encapsulating the support ledge within the split mold insert requires them to also describe part of the body of the preform, which the skilled person will appreciate can have a negative impact on ejection performance.

SUMMARY OF THE INVENTION

The present invention seeks to provide, inter alia, a means by which the body portion described by the split mold insert can be minimised. This invention is directed, in particular but not exclusively, to mold stacks and components thereof, molds, mold assemblies, molding systems and associated methods for making tubular articles, such as preforms. The articles may have a neck portion, which may have an open end. The articles may have a hollow body portion, which may have a closed end. The neck portion may include one or more radial flanges, which may extend outwardly. The neck portion may include engaging features, such as threads or a snap fit finish. The preform and/or neck portion may comprise any one or more other features described above in relation to known preform designs. In addition, any of the foregoing features described in relation to known mold stacks and components thereof, molds and molding systems may be incorporated within mold stacks, molds and molding systems according to the invention, insofar as they are consistent with the disclosure herein.

According to a first broad aspect of the present invention, there is provided a mold stack comprising a cavity insert and a split mold insert with an interface between the cavity insert and split mold insert, wherein the interface comprises a non-mating portion which at least partially surrounds and/or is joined to and/or extends from molding surfaces of each of the cavity insert and split mold inserts and a mating portion which at least partially surrounds the non-mating portion. The provision of a non-mating portion that surrounds and extends from the molding surfaces and is surrounded by a mating portion enables the non-mating portion to be isolated from a clamping load that might otherwise stress the region of the split mold insert adjacent the radial flange.

Another broad aspect of the invention provides a split mold insert comprising a non-mating portion, which at least partially surrounds and/or is joined to and/or extends from a molding surface, and a mating portion which at least partially surrounds the non-mating portion.

Another broad aspect of the invention provides a cavity insert comprising a non-mating portion, which at least partially surrounds and/or is joined to and/or extends from a molding surface, and a mating portion which at least partially surrounds the non-mating portion.

The split mold insert and/or the cavity insert may be for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end. The molding surface of the split mold insert may be for describing part of the hollow body portion and at least the radial flange of the neck portion. The molding surface of the cavity insert may be for describing part of the hollow body portion.

Another broad aspect of the invention provides a mold stack, e.g. for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the mold stack comprising: a cavity insert with a molding surface for describing part of the hollow body portion; a split mold insert with a molding surface for describing part of the hollow body portion and at least the radial flange of the neck portion; and an interface between the cavity insert and the split mold insert; wherein the interface comprises a non-mating portion which at least partially surrounds and/or is joined to and/or extends from the molding surfaces and a mating portion which at least partially surrounds the non-mating portion.

The non-mating portion may describe a gap, e.g. a force isolating gap. The gap may be described between the cavity insert and the split mold insert, e.g. when a clamp force is transmitted, in use, across the mating portion when the mold stack is in a molding configuration.

Another broad aspect of the invention provides a mold stack, e.g. for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the mold stack comprising: a cavity insert with a molding surface for describing part of the hollow body portion; a split mold insert with a molding surface for describing part of the hollow body portion and at least the radial flange of the neck portion; and an interface between the cavity insert and the split mold insert; wherein the interface comprises a non-mating portion which at least partially surrounds and/or is joined to and/or extends from the molding surfaces and a mating portion which at least partially surrounds the non-mating portion, and the non-mating portion describes a gap, e.g. a force isolating gap, between the cavity insert and the split mold insert when a clamp force is transmitted, in use, across the mating portion when the mold stack is in a molding configuration.

At least part of the non-mating portion may be annular or part-annular. At least part of the non-mating portion may extend around and/or about and/or circumscribe the molding surfaces.

Additionally or alternatively, at least part of the non-mating portion may have a radial dimension, which may be at least half, e.g. at least two thirds or three quarters or four fifths or nine tenths, of a radial dimension of the radial flanged described by the molding surface of the split mold insert.

The non-mating portion may comprise one or more non-mating surfaces, for example facing nonmating surfaces. The non-mating portion may comprise at least one surface of each of the split mold insert and the cavity insert. The non-mating portion may comprise facing non-mating surfaces of the split mold insert and cavity insert. At least one or each non-mating surface may, but need not, be planar.

At least part of at least one of the non-mating surface(s) of the split mold insert may be spaced from the radial flange portion by 5mm or less, preferably 3mm or less and more preferably by 2mm or less. In some examples, at least part of at least one of the non-mating surface(s) of the split mold insert is spaced from the radial flange portion by 1mm or less.

The non-mating portion may comprise a first portion. The first portion may extend radially from the molding surfaces. The non-mating portion may comprise a second portion. The second portion may at least partially surround the first portion and/or may extend at an angle therefrom or be substantially perpendicular or orthogonal thereto. The first portion may describe a first gap, e.g. between the cavity insert and the split mold insert. The second portion may describe a second gap, e.g. between the cavity insert and the split mold insert. The first gap may be greater than the second gap or the second gap may be greater than the first gap. The second portion may be joined to and/or extend from the first portion.

The interface may comprise one or more or a plurality of tapers, e.g. two or more or a plurality of cooperating male and female tapers. The tapers may be for aligning the cavity insert and the split mold inserts, e.g. when the mold stack is in the molding configuration.

The split mold insert may comprise a plurality of split mold insert parts. The split mold insert parts may together provide the molding surface, e.g. for describing part of the hollow body portion and at least the radial flange of the neck portion. The split mold insert may comprise, or split mold insert parts may together provide, the male taper. The male taper may be on a cavity side of the split mold insert. The cavity insert may comprise the female taper. At least part of the mating portion may be described the male taper and/or the female taper.

The split mold insert may comprise, or split mold insert parts may together provide, a cavity-side pocket, e.g. at least partially within the male taper and/or extending from the cavity side. The cavityside pocket may comprise a non-mating portion, which may at least partially surround and/or be joined to and/or extend from the molding surface.

The split mold insert may comprise, or split mold insert parts may together provide, a cavity mating portion. The cavity mating portion may at least partially surround the non-mating portion, e.g. of the cavity-side pocket.

The male taper may comprise a first male taper. The split mold insert may comprise, or split mold insert parts may together provide, a second male taper, which may be on a core side of the split mold insert. Alternatively, the split insert may comprise, or split mold insert parts may together provide, a female taper, which may be on a core side of the split mold insert.

The split mold insert may comprise, or split mold insert parts may together provide, a core-side pocket, which may be at least partially within the second male taper and/or may extend from the core side to the molding surface. The split mold insert may be configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion, e.g. but not through the non-mating portion, when the mold stack is in a molding configuration.

Another broad aspect of the invention provides a split mold insert, e.g. for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert including a plurality of split mold insert parts together providing: a molding surface for describing part of the hollow body portion and at least the radial flange of the neck portion; a first male taper on a cavity side of the split mold insert; a cavityside pocket at least partially within the first male taper and extending from the cavity side, the cavityside pocket including a non-mating portion which at least partially surrounds and extends from the molding surface; a cavity mating portion described at least in part by the first male taper, which at least partially surrounds the non-mating portion; a second male taper on a core side of the split mold insert; and a core-side pocket at least partially within the second male taper and extending from the core side to the molding surface; wherein the split mold insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the nonmating portion when the mold stack is in a molding configuration.

The mating portion may comprise one or more planar surfaces. Additionally or alternatively, the mating portion may comprise one or more frustoconical surfaces. In some examples, the mating portion includes both one or more planar surfaces and one or more frustoconical surfaces. The planar surface(s) may be annular or part-annular. The frustoconical surface(s) may be annular or part-annular.

The mating portion may comprise one or more annular or part-annular surfaces. At least one of the annular or part-annular surfaces of the mating portion may be planar and/or oriented radially. The at least one of the annular or part-annular surfaces of the mating portion may be frustoconical. In some examples, the mating portion includes both one or more planar annular or part-annular surfaces and one or more frustoconical annular or part-annular surfaces.

The cooperating male and female tapers may comprise mating frustoconical surfaces. At least part of the clamp force may be transmitted, in use, through the mating frustoconical surfaces, e.g. when the mold stack is in the molding configuration. The cooperating male and female tapers may comprise mating planar surfaces. At least part of the clamp force may be transmitted, in use, through the mating planar surfaces, e.g. when the mold stack is in the molding configuration.

The first male taper may comprise a frustoconical surface. The frustoconical surface may at least partially surround the cavity-side pocket. Alternatively, the first male taper may comprise an extension surface, which may projects from the frustoconical surface and/or at least partially surround the cavityside pocket. The frustoconical surface may describe at least part of the cavity mating portion.

The cavity insert may comprise a female taper. The cavity insert may comprise a spigot, e.g. a cooperating spigot or a spigot that cooperates with the cavity-side pocket of or formed in the split mold insert. The female taper may be on a split mold-side of the cavity insert. The spigot may comprise a split mold-side spigot. The split mold-side spigot may be at least partially circumscribed by the female taper. The split mold-side spigot may include a non-mating portion. The non-mating portion may at least partially surround and extend from the molding surface. The cavity insert may comprise a split mold mating portion. The split mold mating portion may at least partially surround the nonmating portion.

The cavity insert may be configured such that a clamp force is transmitted, in use, to a split mold insert through the cavity mating portion, e.g. but not through the non-mating portion, when the mold stack is in a molding configuration.

Another broad aspect of the invention provides a cavity insert, e.g. for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert comprising: a molding surface for describing part of the hollow body portion; a female taper on a split mold-side of the cavity insert; a split mold-side spigot at least partially circumscribed by the female taper, the split mold-side spigot including a non-mating portion which at least partially surrounds and extends from the molding surface; a split mold mating portion described at least in part by the female taper, which at least partially surrounds the non-mating portion; wherein the cavity insert is configured such that a clamp force is transmitted, in use, to a split mold insert through the cavity mating portion but not through the non-mating portion when the mold stack is in a molding configuration. The female taper of the cavity insert may comprise a frustoconical surface. The frustoconical surface may at least partially surround the split mold-side spigot. Alternatively, the female taper may comprise an extension surface. The frustoconical surface may extend from the extension surface. The extension surface may at least partially surround the split mold-side spigot. The frustoconical surface may describe at least part of the split mold mating portion.

The male taper or first male taper of the split mold insert may be at least partially recessed, e.g. with respect to a surrounding portion of the split mold insert. In other examples, the split mold insert may comprise, or split mold insert parts may together provide, the female taper and/or the cavity insert may comprise the male taper, in which case the male taper may be at least partially recessed, e.g. with respect to a surrounding portion of the cavity insert.

The split mold insert may comprise a cavity-side recess and/or the or a cavity-side recess may be formed in the split mold insert. The cavity-side recess may be on a cavity side of the split mold insert. The male taper may be at least partially within the cavity-side recess. The male taper may comprise the or a non-mating portion, which at least partially surrounds and extends from the molding surface.

Another broad aspect of the invention provides a split mold insert, e.g. for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert including a plurality of split mold insert parts together providing: a molding surface for describing part of the hollow body portion and at least the radial flange of the neck portion; a cavity-side recess on a cavity side of the split mold insert; a male taper at least partially within the cavity-side recess, the male taper including a non-mating portion which at least partially surrounds and extends from the molding surface; and a cavity mating portion described at least in part by the male taper, which at least partially surrounds the non-mating portion; wherein the split mold insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the non-mating portion when the mold stack is in a molding configuration.

Another, broader aspect of the invention provides a split mold insert, e.g. for use in a mold stack for molding a tubular article, the split mold insert including a plurality of split mold insert parts together providing a cavity-side recess on a cavity side of the split mold insert and a male taper at least partially within the cavity-side recess. Yet another broad aspect of the invention provides a split mold insert, e.g. for use in a mold stack for molding a tubular article, the split mold insert including a plurality of split mold insert parts together providing a male taper at least partially recessed with respect to a surrounding portion of the split mold insert parts.

The cavity insert may comprise a projection, e.g. a cooperating projection or a projection that cooperates with the cavity-side recess of or formed in the split mold insert. The projection may comprise a split mold-side projection, e.g. on a split mold side of the cavity insert. The projection may at least partially surround or circumscribe the female taper.

The cavity insert may comprise a female taper at least partially within the split mold-side projection. The female taper may comprise the or a non-mating portion, which may at least partially surround and/or extend from the molding surface. The cavity insert may comprise a split mold mating portion, which may at least partially surround the non-mating portion.

Another aspect of the invention provides a cavity insert for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert comprising: a molding surface for describing part of the hollow body portion; a split mold-side projection on a split mold side of the cavity insert; a female taper at least partially within the split mold-side projection, the female taper including a non -mating portion which at least partially surrounds and extends from the molding surface; and a split mold mating portion described at least in part by the female taper, which at least partially surrounds the non-mating portion; wherein the cavity insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the non-mating portion when the mold stack is in a molding configuration.

The projection may be spaced from the cavity-side recess, e.g. by a circumferential gap, when the mold stack is in a molding configuration. The circumferential gap may be between the outer cylindrical surfaces of the projection and the recess. The circumferential gap may be at least 0.01mm, for example approximately 0.02mm. Additionally or alternatively, the projection may be spaced from the cavity-side recess by an axial gap when the mold stack is in a molding configuration. The axial gap may be between the confronting annular surfaces of the recess and projection. The axial gap may be at least 0.01mm, for example approximately 0.02mm.

The male taper may comprise one of two or more, e.g. a plurality of, male tapers. The two or more or plurality of male tapers may be nested and/or concentric male tapers. The plurality of nested and/or concentric male tapers may each at least partially within the or a respective cavity-side recess.

Another aspect of the invention provides a split mold insert, e.g. for use in a mold stack for molding a tubular article, the split mold insert comprising a plurality of split mold insert parts together providing a plurality of nested and/or concentric tapers.

The female taper may comprise one of two or more, e.g. a plurality of, female tapers. The two or more or plurality of female tapers may be nested and/or concentric female tapers. The cavity insert may comprise a plurality of split mold-side projections, which may be on a split mold side of the cavity insert. The plurality of nested and/or concentric female tapers may each be described within the or a respective split mold-side projection.

Another broad aspect of the invention provides a cavity insert, e.g. for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert comprising: a molding surface for describing part of the hollow body portion; a plurality of split mold-side projections on a split mold side of the cavity insert; a plurality of nested and/or concentric female tapers each described within a respective split mold-side projection; a split mold non-mating portion which at least partially surrounds and extends from the molding surface; and a split mold mating portion described at least in part by the female tapers, which at least partially surrounds the non-mating portion; wherein the cavity insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the non-mating portion when the mold stack is in a molding configuration.

Another, broader aspect of the invention provides a cavity insert, e.g. for use in a mold stack for molding a tubular article, the cavity insert comprising a plurality of nested and/or concentric female tapers. At least one of the nested and/or concentric male tapers may be annular. At least one of the nested and/or concentric male tapers may be part-annular. At least one of the nested and/or concentric female tapers may be annular. At least one of the nested and/or concentric female tapers may be part-annular.

The male and female tapers, e.g. the cooperating male and female tapers, may comprise locating tapers. The male and female tapers may comprise locating tapers, e.g. a plurality of cooperating male and female locating tapers. Each of the tapers, e.g. the cooperating male and female locating tapers, may be spaced around and/or about the non-mating portion and/or centred at a radial distance therefrom. Each of the tapers, e.g. the cooperating male and female locating tapers, may be centred at substantially the same radial distance therefrom.

The split mold insert may comprise a plurality of tapers. Each taper may be spaced around and/or about the non-mating portion. Each taper may be centred at a radial distance therefrom.

Another broad aspect of the invention provides a split mold insert for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert including a plurality of split mold insert parts together providing: a molding surface for describing part of the hollow body portion and at least the radial flange of the neck portion; a cavity-side non-mating portion which at least partially surrounds and extends from the molding surface; a cavity mating portion which at least partially surrounds the nonmating portion; and a plurality of tapers each spaced around and/or about the cavity-side non-mating portion and centred at a radial distance therefrom; wherein the split mold insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the cavity-side non-mating portion when the mold stack is in a molding configuration.

Another, broader aspect of the invention provides a split mold insert for use in a mold stack for molding a tubular article, the split mold insert comprising a plurality of tapers each spaced around and/or about a central axis and centred at a radial distance therefrom.

Each of the tapers, e.g. the plurality of tapers, may be provided by a respective bore in the split mold insert. Alternatively, each of the tapers, e.g. the plurality of tapers, may be provided by a respective projection or male tapers on the split mold insert. The cavity insert may comprise a plurality of tapers. Each taper may be spaced around and/or about the non-mating portion. Each taper may be centred at a radial distance therefrom

Another broad aspect of the invention provides a cavity insert for use in a mold stack for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert comprising: a molding surface for describing part of the hollow body portion; a split mold-side non-mating portion which at least partially surrounds and extends from the molding surface; a split mold mating portion which at least partially surrounds the non-mating portion; and a plurality of tapers each spaced around and/or about the split mold-side non-mating portion and centred at a radial distance therefrom; wherein the cavity insert is configured such that a clamp force is transmitted, in use, to a cavity insert through the cavity mating portion but not through the non-mating portion when the mold stack is in a molding configuration.

Each of the tapers, e.g. the plurality of tapers, may be provided by a respective projection or pin extending from the cavity insert. Alternatively, each of the tapers, e.g. the plurality of tapers, may be provided by a respective bore in the cavity insert.

The mating portion may comprise one or more, e.g. a pair of, substantially planar surfaces. The mating portion may comprise a pair of substantially planar surfaces on opposite sides of the non-mating portion. The or each substantially planar surface may taper or be angled toward the non-mating portion. The pair of substantially planar surfaces may converge toward the non-mating portion.

The cavity insert may comprise a first part. The first part may include at least part of the molding surface. The cavity insert may comprise a second part. The second part may comprise at least part of the mating portion.

Another broad aspect of the invention provides a mold comprising a mold stack or a cavity insert or a split mold insert as described above.

The mold assembly or mold may comprise a stripper plate assembly, e.g. to which the split mold insert is mounted or movably mounted. The stripper plate assembly may comprise a stripper plate and/or one or more, e.g. a pair of, slides, which may be movably mounted to the stripper plate. Each split mold insert part may be mounted to a respective one of the slides. The mold assembly may comprise a plurality of split mold inserts, which may be movably mounted to the stripper plate assembly. The stripper plate assembly may comprise a plurality of slide pairs, which may carry the split mold inserts. The stripper plate may comprise a plurality of core apertures, e.g. through which the core inserts extend.

The stripper plate assembly may comprise one or more wear surfaces or wear plates. The slides may be movable along and/or in contact with the wear surface(s) or plate(s). The or each slide pair may be movable toward and/or away from one another. The or each part of the or each split mold insert may be movable toward and/or away from one another, e.g. by virtue of the relative movement of the slides to which they are mounted.

The mold assembly may comprise two or more cavity inserts, e.g. a plurality of cavity inserts. The mold assembly may comprise a cavity plate, for example to which or within which the or each cavity insert is mounted. The mold assembly may comprise one or more gate inserts, e.g. a plurality of gate inserts. The or each gate insert may comprise or describe a molding surface and/or a gate. The or each gate insert may be mounted to or within the cavity plate, e.g. and/or may engage and/or cooperate with the, or a respective one of the, cavity insert(s).

The cavity plate may comprise one or more, e.g. a plurality of, seats. The or each cavity insert and/or the or each gate insert may be received within the, or a respective one of the, seat(s). The gate insert may comprise a nozzle-receiving pocket and/or a molding surface that may describe a closed end of the preform. In some examples, the cavity insert incorporates the features of the gate insert.

The mold assembly may comprise a melt flow distributor, which may be mounted to the cavity plate. The melt flow distributor may comprise one or more, e.g. a plurality of, nozzles. The or each nozzle may cooperate with and/or engage the gate of the, or a respective one of the, gate inserts. The cavity plate may comprise a melt flow distributor facing side, e.g. to which the melt flow distributor is mounted. The cavity plate assembly may comprise a core facing side, e.g. opposite the melt flow distributor facing side. The female taper of the or each cavity insert may be on the core facing side of the cavity plate. The mold stack may comprise a core insert. The core insert may comprise a molding surface. The stripper plate assembly may be movable, e.g. along the core insert. The mold assembly or mold may comprise a core plate, e.g. to which the core insert is mounted. The mold assembly may comprise a plurality of core inserts, which may be mounted to the core plate. Each core insert may have a molding surface.

The stripper plate and/or stripper plate assembly may comprise a cavity facing side and/or a core facing side, e.g. opposite the cavity facing side. The stripper plate may be located on the core facing side of the stripper plate assembly. The wear plate(s) and/or slides and/or split mold insert(s) may be on the cavity facing side of the stripper plate or stripper plate assembly. The core plate may comprise a mounting side and/or a cavity or stripper plate facing side, e.g. opposite the mounting side. The core(s) may be mounted to the core plate such that they project from the cavity or stripper plate facing side thereof. The stripper plate assembly may be mounted, e.g. movably mounted, to the core plate such that the core(s) are received within and/or movable along the core aperture(s). The guide(s), e.g. the cam(s), may be mounted, e.g. fixed, to the core plate. Movement of the stripper plate assembly relative to the core plate may cause the cam followers to move along the cams.

Another aspect of the invention provides a computer program element comprising and/or describing and/or defining a three-dimensional design for use with a simulation means or a three-dimensional additive or subtractive manufacturing means or device, e.g. a three-dimensional printer or CNC machine, the three-dimensional design comprising a mold assembly, mold, split mold insert, core, bearing plate or any one or more other mold components described above.

For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible.

For the avoidance of doubt, the terms “may”, “and/or”, “e.g.”, “for example” and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 depicts a part of a preform mold incorporating a mold stack according to a first example;

FIG. 2 is an enlarged view of the mold stack of FIG. 1, illustrating the interface between the cavity insert and the split mold insert;

FIG. 3 is a perspective view of the cavity insert of the mold stack of FIGs. 1 and 2, from the split mold insert facing side;

FIG. 4 is a perspective view of the split mold insert of the mold stack of FIGs. 1 and 2, from the cavity insert facing side;

FIG. 5 is an enlarged view similar to that of FIG. 2 for an alternative mold stack, illustrating the interface between the cavity insert and the split mold insert;

FIG. 6 is a perspective view of the cavity insert of the mold stack of FIG. 5 from the split mold insert facing side;

FIG. 7 is a perspective view of the split mold insert of the mold stack of FIG. 5 from the cavity insert facing side;

FIG. 8 is an enlarged view similar to that of FIG. 2 for another alternative mold stack, illustrating the interface between the cavity insert and the split mold insert; FIG. 9 is a perspective view of the cavity insert of the mold stack of FIG. 8 from the split mold insert facing side;

FIG. 10 is a perspective view of the split mold insert of the mold stack of FIG. 8 from the cavity insert facing side;

FIG. 11 is an enlarged view similar to that of FIG. 2 for another alternative mold stack, illustrating the interface between the cavity insert and the split mold insert;

FIG. 12 is an enlarged view of area A of FIG. 11;

FIG. 13 is a perspective view of the cavity insert of the mold stack of FIG. 11 from the split mold insert facing side;

FIG. 14 is a perspective view of the split mold insert of the mold stack of FIG. 11 from the cavity insert facing side;

FIG. 15 is an enlarged view similar to that of FIG. 2 for another alternative mold stack, illustrating the interface between the cavity insert and the split mold insert;

FIG. 16 is a perspective view of the cavity insert of the mold stack of FIG. 15 from the split mold insert facing side; and

FIG. 17 is a perspective view of the split mold insert of the mold stack of FIG. 15 from the cavity insert facing side.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, there is depicted a non-limiting embodiment of part of a mold assembly 100, which includes a core plate assembly 101, a stripper plate assembly 102 and a cavity plate assembly 103 together incorporating a plurality of mold stacks 104, only one of which is shown. Each mold stack 104 describes, in a molding configuration as shown in FIG. 1, a cavity describing a preform P. The mold assembly 100 may also include a melt distributor (not shown) secured to the exposed side of the cavity plate assembly 103 for injecting molten material into the mold stacks 104.

The core plate assembly 101 includes a core plate 110 to which a core assembly 111 of each mold stack 104 is mounted. Each core assembly 111 includes a hollow core insert 112, a core ring 113 surrounding and engaging a seat of the core insert 112, a lock ring 114 surrounding the core insert 112 and core ring 113 and a core cooling tube 115 received within the hollow core insert 112. The lock ring 114 is secured to the core plate 110 by bolts B, and has an inner taper that engages with an outer taper of the core ring 113 to secure the core ring 113 and core insert 112 to the core plate 110 in the usual way.

The core insert 112 has a spigot 112a projecting from a first, open end thereof, which is received within a seat 110a of the core plate 110, and a molding surface 112b at a second, closed end, for describing an inner surface of the preform P. The core cooling tube 115 is engaged within the seat 110a of the core plate 110 for receiving cooling fluid from a network of cooling channels 110b within the core plate 110, which then flows along the core cooling tube 115 and is directed to an inner surface of the closed end of the core insert 112, before being redirected back along the outside of the core cooling tube 115 and into the network of cooling channels 110b in the usual way.

The stripper plate assembly 102 includes a stripper plate 120, wear plates 121 mounted to the stripper plate 120, slides 122 movably mounted to the wear plates 121 and a split mold insert 123 of each mold stack 104 mounted to the slides 122. More specifically, the split mold insert 123 includes two split mold insert parts 123a, 123b in this example, and each split mold insert part 123a, 123b is mounted to a respective one of the slides 122. The skilled person will appreciate that the stripper plate assembly 102 will include a plurality of pairs of slides 122 and each slide 122 of each pair carries a respective one of the split mold insert parts 123a, 123b of each of a plurality of mold stacks 104. Each slide 122 is connected to one of the slides 122 of each of the other pairs of slides 122, thereby to enable separation of all split mold insert parts 123 a, 123b simultaneously during demolding of the preforms P, in the usual way.

The cavity plate assembly 103 includes a cavity plate 130 to which a cavity insert 131 of each mold stack 104 is mounted. The cavity insert 131 in this example is split into a cavity part 132 and a cavity flange 133, but it will be appreciated by those skilled in the art that these two components may be provided as a unitary body. The cavity part 132 is received within a seat 130a of the cavity plate 130. In this example, each mold stack 104 also includes a gate insert 134 received within the seat 130a, which abuts the cavity part 132. The gate insert 134 includes a nozzle-receiving pocket 134a and a molding surface 134b, which describes a closed end of the preform P.

Referring now to FIGs. 2 to 4, the split mold insert 123 describes a molding surface 124 that describes an open-ended neck portion of the preform P. More specifically, the molding surface 124 includes a thread portion 124a, a radial flange portion 124b and a hollow body portion 124c. The cavity insert 131, or more specifically the cavity part 132 of the cavity insert 131, describes a molding surface 135 for describing a part of the hollow body portion. The molding surface 134b of the gate insert 134 provides a continuation of the molding surface 135 of the cavity insert 131. The skilled person will appreciate, however, that the cavity part 132 may incorporate the features of the gate insert 134.

The split mold insert 123 in this example includes a cavity-side recess 125 and a male taper 126 within the cavity-side recess 125. The cavity insert 131, or more specifically the cavity flange 133 of the cavity insert 131, includes a projection 136, which has a complimentary shape to the cavity-side recess 125 of the split mold insert 123. A female taper 137 is formed within the projection 136, in part by the cavity flange 133 and in part by the cavity part 132.

When the mold stack 104 is in a molding configuration, the male and female tapers 126, 137 form an interface 140 between the split mold insert 123 and the cavity insert 131. The interface 140 includes a non-mating portion 141 and a mating portion 142. The non-mating portion 141 surrounds and extends from the molding surfaces 124, 135, while the mating portion 142 surrounds the non-mating portion 141. The non-mating portion 141 in this example is described by facing planar surfaces 141a, 141b of the split mold insert 123 and the cavity insert 131. The mating portion 142 in this example is described by frustoconical surfaces 142a, 142b and surrounding planar surfaces 142e, 142f of the split mold insert 123 and the cavity insert 131.

The non-mating surface 141a of the split mold insert 123 corresponds to a truncated apex of the male taper 126. The non-mating surface 141b of the cavity insert 131 corresponds to a base of the female taper 137, which is formed by the cavity part 132. The split mold insert 123 includes a first mating surface 142a that corresponds to an exterior of the male taper 126 and a second mating surface 142e that surrounds the cavity side recess 125. The cavity insert 131 includes a first mating surface 142b that corresponds to an interior surface of the female taper 137 facing the male taper 126 of the split mold insert 123 and a second mating surface 142f that surrounds the projection 136 facing the second mating surface 14e of the cavity insert 131. The non-mating surfaces 141a, 141b of the split mold insert 123 and the cavity insert 131 circumscribe and extend from their respective molding surfaces 124, 135, and are non-mating by virtue of a gap G therebetween. The mating surfaces 142a, 142b of the split mold insert 123 and the cavity insert 131 circumscribe the non-mating surfaces 141a, 141b and are in contact with one another.

The gap G is dimensioned to isolate the non-mating portion 141 from a clamping load applied, in use, to the mold assembly 100, while inhibiting molding material from passing therethrough. In this example, the molding material is polyethylene terephthalate (PET) and the gap G is 0.03 mm. As a result, the clamping load passes through the mating surfaces 142a, 142b of the mating portion 142, while the non-mating portion 141 is isolated from the clamping load that might otherwise stress the region of the split mold insert 123 adjacent the radial flange portion 124b. This, force-isolating gap G enables the distance between the non-mating surface 141a of the split mold insert 123 and the radial flange portion 124b to be minimised, whilst mitigating the risk of overstressing that region of the split mold insert 123. By way of example, the distance between the non -mating surface 141a of the split mold insert 123 and the radial flange portion 124b may be 2 mm and could be less.

In this example, the projection 136 of the cavity insert 131 is also spaced from the facing surfaces of the cavity-side recess 125 of the split mold insert 123 by both an axial gap, which is between the confronting annular surfaces of the recess and projection, and a circumferential gap, which is between the outer cylindrical surfaces of the projection and the recess, when the mold stack 104 is in a molding configuration. In this example, both the axial gap and the circumferential gap are approximately 0.02mm. As a result, substantially all of the clamping force passing between the split mold insert 123 and the cavity insert 131 is through the mating surfaces 142a, 142b, 142e, 142f of the mating portion 142 of the interface 140.

Turning now to FIGs. 5 to 7, there is shown an alternative mold stack 204 which is similar to the example described above, wherein like features are depicted with like references incremented by 100 and will therefore not be described further. The mold stack 204 according to this example differs from that of the previous example in that the interface 240 incorporates a plurality of nested and concentric tapers 226, 237. As with the previous example, the interface 240 includes a non-mating portion 241 and a mating portion 242, and the non -mating portion 241 surrounds and extends from the molding surfaces 224, 235 while the mating portion 242 surrounds the non -mating portion 241. The non-mating portion 241 is also described by facing planar surfaces 241a, 241b of the split mold insert 223 and the cavity insert 231. The non-mating surfaces 241a, 241b of the split mold insert 223 and the cavity insert 231 also circumscribe and extend from their respective molding surfaces 224, 235, and are non-mating by virtue of a gap G therebetween.

However, in this example the mating portion 242 is described by a plurality of facing frustoconical surfaces 242a, 242b, and by facing planar surfaces 242c, 242d of the split mold insert 223 and the cavity insert 231. The mating frustoconical surfaces 242a of the split mold insert 223 correspond to the exteriors of the male tapers 226, while the mating surface 242b of the cavity insert 231 correspond to the facing interior surfaces of the female tapers 237. The mating planar surfaces 242c, 242d of the split mold insert 223 and the cavity insert 231 circumscribe the non-mating planar surfaces 241a, 241b and are in contact with one another. As such, the innermost male taper 226 has a truncated apex with a shallow step that delineates the mating planar surface 242c of the split mold insert 223 from its nonmating planar surface 241a. However, the base of the innermost female taper 237 of the cavity insert 231 has no such step and, as such, the mating planar surface 242d of the cavity insert 231 is coplanar with its non-mating planar surface 241b. The skilled person will appreciate that the base of the innermost female taper 237 of the cavity insert 231 may include the shallow step in addition to, or instead of, the shallow step on the truncated apex of the innermost male taper 226.

As in the first example, the gap G is dimensioned to isolate the non-mating portion 241 from a clamping load, while inhibiting molding material from passing therethrough. As a result, the clamping load passes through the mating surfaces 242a, 242b, 242c, 242d of the mating portion 242, while the non-mating portion 241 is isolated from the clamping load that might otherwise stress the region of the split mold insert 223 adjacent the radial flange portion 224b. This, force-isolating gap G enables the distance between the non-mating surface 241a of the split mold insert 223 and the radial flange portion 224b to be minimised whilst mitigating the risk of overstressing that region of the split mold insert 223. By way of example, the distance between the non-mating surface 241a of the split mold insert 223 and the radial flange portion 224b may be 2 mm and could be less. Similar to the first example, the projections 236 of the cavity insert 231 are spaced from the facing surfaces of the cavity-side recesses 225 of the split mold insert 223 by both an axial gap and a circumferential gap when the mold stack 204 is in a molding configuration. As a result, substantially all of the clamping force passing between the split mold insert 223 and the cavity insert 231 is through the mating surfaces 242a, 242b, 242c, 242d of the mating portion 242 of the interface 240. Other arrangements are also envisaged, as will be appreciated by the skilled person.

Turning now to FIGs. 8 to 10, there is shown an alternative mold stack 304 which is similar to the first mold stack 104 described above, wherein like features are depicted with like references incremented by 200 and will therefore not be described further. The mold stack 304 according to this example differs from that of the first example in that the interface 340 includes a cavity-side pocket 328 in the male taper 326 of the split mold insert 323 that receives a split mold-side spigot 338 circumscribed by the female taper 337 of the cavity insert 331. In this example, the male taper 326 projects from the body of the split mold insert 323, rather than being located within a cavity-side recess 125.

As with the previous example, the interface 340 includes a non-mating portion 341 and a mating portion 342, and the non-mating portion 341 surrounds and extends from the molding surfaces 324, 335 while the mating portion 342 surrounds the non-mating portion 341. The non-mating portion 341 is also described by facing planar surfaces 341a, 341b of the split mold insert 323 and the cavity insert 331. The non-mating surfaces 341a, 341b of the split mold insert 323 and the cavity insert 331 also circumscribe and extend from their respective molding surfaces 324, 335, and are non-mating by virtue of a gap G therebetween.

However, in this example the non-mating surface 341a of the split mold insert 323 corresponds to the base of the cavity-side pocket 328 and the non-mating surface 341b of the cavity insert 331 corresponds to the free end of the split mold-side spigot 338. The diameter of the inner circumference of the cavity-side pocket 328 is also slightly larger than that of the outer circumference of the split mold-side spigot 338. In addition, the mating portion 342 includes not only the facing frustoconical surfaces 342a, 342b of the tapers 326, 337 and the planar surrounding surfaces 342e, 342f, as in the mold stack 104 of the first example, but it also includes facing planar surfaces 342c, 342d of the truncated apex of the male taper 326 of the split mold insert 323 and the base of the female taper 337 of the cavity insert 331. The mating planar surfaces 342c, 342d, 342e, 342f and frustoconical surfaces 342a, 342b of the split mold insert 323 and the cavity insert 331 circumscribe the non-mating planar surfaces 341a, 341b and are in contact with one another.

As in the previous examples, the gap G is dimensioned to isolate the non-mating portion 341 from a clamping load, while inhibiting molding material from passing therethrough. As a result, the clamping load passes through the mating surfaces 342a, 342b, 342c, 342d, 342e, 342f of the mating portion 342, while the non-mating portion 341 is isolated from the clamping load that might otherwise stress the region of the split mold insert 323 adjacent the radial flange portion 324b. This, force-isolating gap G enables the distance between the non-mating surface 341a of the split mold insert 323 and the radial flange portion 324b to be minimised whilst mitigating the risk of overstressing that region of the split mold insert 323. By way of example, the distance between the non-mating surface 341a of the split mold insert 323 and the radial flange portion 324b may be 2 mm and could be less.

Turning now to FIGs. 11 to 14, there is shown an alternative mold stack 404 which is similar to the mold stack 304 of FIGs. 8 to 10, wherein like features are depicted with like references incremented by 100 and will therefore not be described further. The mold stack 404 according to this example differs from that of FIGs. 8 to 10 in that the male taper 426 includes an axial annular extension 426a, which is received within an annular recess 432a in the cavity part 432. The axial end of the annular extension 426a of the male taper 426 also describes a planar surface 441c spaced from the base of the annular recess 432a, which describes a facing planar surface 44 Id.

The skilled person will also appreciate from FIG. 12 that the exterior of the annular extension 426a of the male taper 426 is spaced from the interior of the annular recess 432a that circumscribes the annular extension 426a. The skilled person will appreciate that this clearance inhibits the risk of the outer comer of the truncated apex of the male taper 426 of the split mold insert 423 from catching on the female taper 437. The non-mating portion 441 in this example therefore includes all of the facing surfaces between the split mold insert 423 and the cavity insert 431 that are circumscribed by the frustoconical mating surfaces 442a, 442b.

Turning now to FIGs. 15 to 17, there is shown an alternative mold stack 504 which is similar to the mold stack 104 of FIGs. 1 to 4, wherein like features are depicted with like references incremented by 400 and will therefore not be described further. The mold stack 504 according to this example differs from that of the first example in that the cooperating tapers 126, 137 are replaced with six locating tapers 526, 537 spaced around and/or about the non-mating portion 541 and centred at substantially the same radial distance therefrom.

More specifically, the cavity flange 533 of the cavity insert 531 includes six stepped holes 527a and six pins 527b each with a male taper 526 projecting from a split mold-side of the cavity flange 533 and a stepped base 527c inserted into one of the stepped holes 527a from the opposite side of the cavity flange 533. The split mold insert 523 includes six female tapers 537 provided by blind tapered holes extending into a cavity-side of the split mold insert 523.

The pins 527 may be press-fit into the stepped holes 527a, but the skilled person will appreciate that they will also be captivated therein when the cavity flange 533 is secured to the cavity plate 130. Other means of providing the locating tapers is also envisaged. In particular, the stepped base 527 may be omitted, wherein the pins 527b may be inserted from the cavity-side of the split mold insert 523 and secured within the stepped holes 527a by respective fasteners (not shown) engaged within threaded holes (not shown) in the pins 527b and abutting the step of the stepped holes 527a. Another alternative would be to form the male tapers 526 integrally with the cavity flange 533. The skilled person will appreciate yet further possible configurations.

As with the previous example, the interface 540 includes a non-mating portion 541 and a mating portion 542, and the non -mating portion 541 surrounds and extends from the molding surfaces 524, 535 while the mating portion 542 surrounds the non-mating portion 541. The non-mating portion 541 is also described by facing planar surfaces 541a, 541b of the split mold insert 523 and the cavity insert 531. The non-mating surfaces 541a, 541b of the split mold insert 523 and the cavity insert 331 also circumscribe and extend from their respective molding surfaces 524, 535, and are non-mating by virtue of a gap G therebetween.

However, in this example the non-mating surface 541a of the split mold insert 523 is not formed on, in or around the male tapers 526, but simply on the cavity-side surface of the split mold insert 523. In addition, the mating portion 542 includes the facing frustoconical surfaces 543a, 543b of the tapers 526, 537 and facing planar surfaces 542c, 542d that surround and are substantially contiguous with the non-mating planar surfaces 541a, 541b. The non-mating planar surface 541b of the cavity insert 531 is formed by the cavity part 532, while the mating planar surface 542d of the cavity insert 531 is formed by a surrounding portion of the cavity flange 533. The non-mating planar surface 541b formed by the cavity part 532 may be recessed slightly compared with the mating planar surface 542d formed by a surrounding portion of the cavity flange 533 to provide the gap G. Additionally or alternatively, the non-mating surface 541a of the split mold insert 523 may be recessed slightly compared with the mating surface 542c thereof to provide the gap G.

As in the previous examples, the gap G is dimensioned to isolate the non-mating portion 541 from a clamping load, while inhibiting molding material from passing therethrough. As a result, the clamping load passes through the mating surfaces 542c, 542d, 543 a, 543b of the mating portion 542, while the non-mating portion 541 is isolated from the clamping load that might otherwise stress the region of the split mold insert 523 adjacent the radial flange portion 524b. This, force-isolating gap G enables the distance between the non-mating surface 541a of the split mold insert 523 and the radial flange portion 524b to be minimised whilst mitigating the risk of overstressing that region of the split mold insert 523. By way of example, the distance between the non-mating surface 541a of the split mold insert 523 and the radial flange portion 524b may be 2 mm and could be less.

It will be appreciated that the configuration of the elements of the mold assembly 100 may vary, particularly although not exclusively as described above. It will also be appreciated by those skilled in the art that several variations to the construction and/or use of aforementioned examples are envisaged without departing from the scope of the invention. It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.

Claims

1. A mold stack (104, 204, 304, 404, 504) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the mold stack (104, 204, 304, 404, 504) comprising: a cavity insert (131, 231, 331, 431, 531) with a molding surface (135, 235, 335, 435, 535) for describing part of the hollow body portion; a split mold insert (123, 223, 323, 423, 523) with a molding surface (124, 224, 324, 424, 524) for describing part of the hollow body portion and at least the radial flange of the neck portion; and an interface (140, 240, 340, 440, 540) between the cavity insert (131, 231, 331, 431, 531) and the split mold insert (123, 223, 323, 423, 523); wherein the interface (140, 240, 340, 440, 540) comprises a non-mating portion (141, 241, 341, 441, 541) which at least partially surrounds and extends from the molding surfaces (124, 135, 224, 235, 324, 335, 424, 435, 524, 535) and a mating portion (142, 242, 342, 442, 542) which at least partially surrounds the non-mating portion (141, 241, 341, 441, 541), and the nonmating portion (141, 241, 341, 441, 541) describes a gap (G) between the cavity insert (131, 231, 331, 431, 531) and the split mold insert (123, 232, 332, 432, 532) when a clamp force is transmitted, in use, across the mating portion (142, 242, 342, 442, 542) when the mold stack (104, 204, 304, 404, 504) is in a molding configuration.

2. The mold stack (104, 204, 304, 404, 504) of claim 1, wherein at least part of the non-mating portion (141, 241, 341, 441, 541) is annular and circumscribes the molding surfaces (141, 241, 341, 441, 541).

3. The mold stack (104, 204, 304, 404, 504) of claim 2, wherein the annular non-mating portion (141, 241, 341, 441, 541) has a radial dimension that is at least half of a radial dimension of the radial flange described by the molding surface (141, 241, 341, 441, 541) of the split mold insert (123, 223, 323, 423, 523).

4. The mold stack (104, 204, 304, 404, 504) of any preceding claim, wherein the non-mating portion (141, 241, 341, 441, 541) comprises facing non-mating surfaces (141a, 141b, 241a, 241b, 341a, 341b, 441a, 441b, 541a, 541b) of the split mold insert (123, 223, 323, 423, 523) and cavity insert (131, 231, 331, 431, 531), and at least part of the non-mating surface (141a, 241a, 341a, 441a, 541a) of the split mold insert (123, 223, 323, 423, 523) is spaced from the radial flange portion by 2mm or less.

5. The mold stack (104, 204, 304, 404, 504) of any preceding claim, wherein the mating portion (142, 242, 342, 442, 542) comprises one or more annular or part-annular surfaces (142a, 142b, 142e, 142f, 242a, 242b, 242c, 242d, 342a, 342b, 342c, 342d, 342e, 342f, 442a, 442b, 442e, 442f, 543a, 543b, 542c, 542d).

6. The mold stack (104, 204, 304, 404, 504) of claim 5, wherein at least one of the annular or partannular surfaces (142e, 142f, 242c, 242d, 342c, 342d, 342e, 342f, 442e, 442f, 542c, 542d) of the mating portion (142, 242, 342, 442, 542) is oriented radially.

7. The mold stack (104, 204, 304, 404, 504) of claim 5 or claim 6, wherein at least one of the annular or part-annular surfaces (142a, 142b, 242a, 242b, 342a, 342b, 442a, 442b, 543a, 543b) of the mating portion (142, 242, 342, 442, 542) is frustoconical.

8. The mold stack (104, 204, 304, 404, 504) of any preceding claim, wherein the interface (140, 240, 340, 440, 540) comprises cooperating male and female tapers (126, 137, 226, 237, 326, 337, 426, 437, 526, 537) for aligning the cavity insert (131, 231, 331, 431, 531) and the split mold inserts (123, 223, 323, 423, 523) when the mold stack (104, 204, 304, 404, 504) is in the molding configuration.

9. The mold stack (104, 204, 304, 404, 504) of claim 8, wherein the cooperating male and female tapers (126, 137, 226, 237, 326, 337, 426, 437, 526, 537) comprise mating frustoconical surfaces through which at least part of the clamp force is transmitted, in use, when the mold stack (104, 204, 304, 404, 504) is in the molding configuration.

10. The mold stack (104, 204) of claim 8 or claim 9, wherein the split mold insert (123, 223) comprises the male taper (126, 226) and the male taper (126, 226) is at least partially recessed with respect to a surrounding portion of the split mold insert (123, 223).

11. The mold stack (104, 204) of claim 10, wherein the male taper (126, 226) is at least partially within a cavity-side recess (125, 225) formed in the split mold insert (123, 223) and the cavity insert (131, 231) comprises a cooperating projection (136, 236) circumscribing the female taper (137, 237).

12. The mold stack (104, 204) of claim 11, wherein the projection (136, 236) is spaced from the cavity-side recess (125, 225) by a circumferential gap and by an axial gap when the mold stack (104, 204) is in a molding configuration.

13. The mold stack (204) of any one of claims 8 to 12, wherein the male taper (226) comprises one of a plurality of nested and/or concentric male tapers (226).

14. The mold stack (504) of claim 8, wherein the cooperating male and female tapers (526, 537) comprise locating tapers (526, 537).

15. The mold stack (504) of claim 14 comprising a plurality of cooperating male and female locating tapers (526, 537) each spaced around the non-mating portion (541) and centred at substantially the same radial distance therefrom.

16. The mold stack (104, 204, 304, 404, 504) of any preceding claim, wherein the cavity insert (131, 231, 331, 431, 531) comprises a first part (132, 232, 332, 432, 532) including at least part of the molding surface (135, 235, 335, 435, 535) and a second part (133, 233, 333, 433, 533) comprising at least part of the mating portion (142, 242, 342, 442, 542).

17. A mold assembly (100) comprising a mold stack (104, 204, 304, 404, 504) according to any preceding claim.

18. A split mold insert (323, 423) for use in a mold stack (304, 404) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert (323, 423) including a plurality of split mold insert parts (323a, 323b, 423a, 423b) together providing: a molding surface (324, 424) for describing part of the hollow body portion and at least the radial flange of the neck portion; a first male taper (326, 426) on a cavity side of the split mold insert (323, 423); a cavity-side pocket (328, 428) at least partially within the first male taper (326, 426) and extending from the cavity side, the cavity-side pocket (328, 428) including a non-mating portion (341, 441) which at least partially surrounds and extends from the molding surface (324, 424); a cavity mating portion (342, 442) described at least in part by the first male taper (326, 426), which at least partially surrounds the non-mating portion (341, 441); a second male taper on a core side of the split mold insert (323, 423); and a core-side pocket at least partially within the second male taper and extending from the core side to the molding surface (324, 424); wherein the split mold insert (323, 423) is configured such that a clamp force is transmitted, in use, to a cavity insert (331, 431) through the cavity mating portion (342, 442) but not through the non-mating portion (341, 441) when the mold stack (304, 404) is in a molding configuration.

19. The split mold insert (323, 423) of claim 18, wherein the first male taper (326, 426) comprises a frustoconical surface (342a, 442a) at least partially surrounding the cavity-side pocket (328, 428).

20. The split mold insert (423) of claim 18, wherein the first male taper (426) comprises a frustoconical surface (442a) and an extension surface which projects from the frustoconical surface (442a) and at least partially surrounds the cavity-side pocket (428).

21. The split mold insert (323) of claim 19 or claim 20, wherein the frustoconical surface (342a) describes at least part of the cavity mating portion (342).

22. A split mold insert (123, 223) for use in a mold stack (104, 204) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert (123, 223) including a plurality of split mold insert parts (123a, 123b, 223a, 223b) together providing: a molding surface (124, 224) for describing part of the hollow body portion and at least the radial flange of the neck portion; a cavity-side recess (125, 225) on a cavity side of the split mold insert (123, 223); a male taper (126, 226) at least partially within the cavity-side recess (125, 225), the male taper (126, 226) including a non-mating portion (141, 241) which at least partially surrounds and extends from the molding surface (124, 224); and a cavity mating portion (142, 242) described at least in part by the male taper (126, 226), which at least partially surrounds the non-mating portion (141, 241); wherein the split mold insert (123, 223) is configured such that a clamp force is transmitted, in use, to a cavity insert (131, 231) through the cavity mating portion (142, 242) but not through the non-mating portion (141, 241) when the mold stack (104, 204) is in a molding configuration.

23. The split mold insert (223) of claim 22, wherein the male taper (226) comprises one of a plurality of nested and/or concentric male tapers (226) each at least partially within the or a respective cavity-side recess (225).

24. A cavity insert (231) for use in a mold stack (204) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert (231) comprising: a molding surface (224) for describing part of the hollow body portion; a plurality of split mold-side projections (236) on a split mold side of the cavity insert (231); a plurality of nested and/or concentric female tapers (237) each described within a respective split mold-side projection (236); a split mold non-mating portion (241) which at least partially surrounds and extends from the molding surface (224); and a split mold mating portion (242) described at least in part by the female tapers (237), which at least partially surrounds the non-mating portion (241); wherein the cavity insert (231) is configured such that a clamp force is transmitted, in use, to a split mold insert insert (223) through the split mold mating portion (242) but not through the non-mating portion (241) when the mold stack (204) is in a molding configuration.

25. A split mold insert (223) for use in a mold stack (204) for molding a tubular article, the split mold insert (223) comprising a plurality of split mold insert parts (223a, 223b) together providing a plurality of nested and/or concentric tapers (225).

26. A cavity insert (231) for use in a mold stack (204) for molding a tubular article, the cavity insert (231) comprising a plurality of nested and/or concentric tapers (225).

27. A split mold insert (523) for use in a mold stack (504) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the split mold insert (523) including a plurality of split mold insert parts (523a, 523b) together providing: a molding surface (524) for describing part of the hollow body portion and at least the radial flange of the neck portion; a cavity-side non-mating portion (541) which at least partially surrounds and extends from the molding surface (524); a cavity mating portion (542) which at least partially surrounds the non-mating portion (541); and a plurality of tapers (537) each spaced around the cavity-side non-mating portion (541) and centred at a radial distance therefrom; wherein the split mold insert (523) is configured such that a clamp force is transmitted, in use, to a cavity insert (531) through the cavity mating portion (542) but not through the cavityside non-mating portion (541) when the mold stack (504) is in a molding configuration.

28. The split mold insert (523) of claim 27, wherein each of the plurality of tapers (537) is provided by a respective bore in the split mold insert (523).

29. A cavity insert (531) for use in a mold stack (504) for molding a tubular article having a neck portion with a radial flange and an open end, and a hollow body portion with a closed end, the cavity insert (531) comprising: a molding surface (524) for describing part of the hollow body portion; a split mold-side non-mating portion (541) which at least partially surrounds and extends from the molding surface (524); a split mold mating portion (542) which at least partially surrounds the non-mating portion (541); and a plurality of tapers (526) each spaced around the split mold-side non -mating portion (541) and centred at a radial distance therefrom; wherein the cavity insert (531) is configured such that a clamp force is transmitted, in use, to a split mold insert (523) through the split mold mating portion (542) but not through the nonmating portion (541) when the mold stack (504) is in a molding configuration.

30. The cavity insert (531) of claim 29, wherein each of the plurality of tapers (526) may be provided by a respective projection or pin extending from the cavity insert (531).