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Title:
MOLDS, MOLD ASSEMBLIES AND STACK COMPONENTS
Document Type and Number:
WIPO Patent Application WO/2021/035336
Kind Code:
A1
Abstract:
A preform mold (100) having a plurality of mold stacks (MS) for molding preforms (P). The mold includes a stripper plate assembly (300, 1300) having a stripper plate (310) with air channels (416) each having an outlet (416a). The stripper plate assembly (300, 1300) is movable along a core insert (250, 1250) from a first position to a second position. In the second position, the outlet (416a) of the air channel (416) is clear of a shank (251a, 1251a) of the core insert and supplies a pressurised flow (A) of air toward the molding surface (252, 1252) of the core insert (250, 1250).

Inventors:
MCCREADY DEREK ROBERTSON (CA)
ANWER ALI OWAIS (CA)
Application Number:
PCT/CA2020/051137
Publication Date:
March 04, 2021
Filing Date:
August 21, 2020
Export Citation:
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Assignee:
HUSKY INJECTION MOLDING SYSTEMS LTD (CA)
International Classes:
B29C33/46; B29C33/68
Domestic Patent References:
WO2012019304A12012-02-16
WO2010017622A12010-02-18
Foreign References:
US20060204608A12006-09-14
US20010028930A12001-10-11
Attorney, Agent or Firm:
GOW, Geoffrey (CA)
Download PDF:
Claims:
CLAIMS

1. A mold assembly (100) for molding tubular articles (P), the assembly comprising: a core insert (250, 1250) with a molding surface (252, 1252), a shank (251, 1251) and an annular shoulder (251c, 1251c) therebetween; a core plate (210) to which the core insert (250, 1250) is mounted; a split mold insert (350, 1350) with an annular spigot (353, 1353) that engages the annular shoulder (251c, 1251c) of the core insert (250, 1250) for transmitting a clamping load to the shank (251, 1251) when the assembly is in a molding configuration; and a stripper plate assembly (300) to which the split mold insert (350, 1350) is movably mounted, the stripper plate assembly (300) comprising an air channel (316) with an outlet (316a); wherein the stripper plate assembly (300) is movable along the core insert (250, 1250) from a first position, in which the annular spigot (353, 1353) of the split mold insert (350, 1350) abuts the annular shoulder (251c, 1251c) of the core insert (250, 1250) and the outlet (316a) of the air channel (316) of the stripper plate assembly (300) is obstructed by the shank (251, 1251) of the core insert (250, 1250), to a second position, in which the outlet (316a) of the air channel (316) is clear of the shank (251, 1251) for supplying, in use, a pressurised flow of air (A) toward the molding surface (252, 1252) of the core insert (250, 1250).

2. A mold assembly (100) according to claim 1, wherein the stripper plate assembly (300) comprises a stripper plate (310) and a pair of slides (320a, 320b) movably mounted to the stripper plate (310), the split mold insert (350, 1350) comprising two parts (350a, 350b, 1350a, 1350b) each of which is mounted to a respective one of the slides (320a, 320b), each slide (320a, 320b) having a recess (321) within which part of the annular spigot (353, 1353) is received and the length of the annular spigot (353, 1353) is equal to or less than the depth of the slides (320a, 320b) such that the annular spigot (353, 1353) is spaced from the stripper plate (310).

3. A mold assembly (100) according to claim 2, wherein the annular shoulder (25 lc, 125 lc) of the core insert (250, 1250) is provided by a radial step between the shank (251, 1251) and an annular recess (251b), the annular spigot (353, 1353) of the split mold insert (350, 1350) being received within the annular recess (251b) when the stripper plate assembly (300) is in the first position such that part of the shank (251, 1251) of the core insert (250, 1250) is received within the recesses (321) of the slides (320a, 320b).

4. A mold assembly (100) according to claim 3, wherein the outlet (316a) of the air channel (316) is aligned with the annular recess (25 lb) when the stripper plate assembly (300) is in the second position.

5. A mold assembly (100) according to claim 3 or claim 4, wherein the radial step describes an annular seat (25 Id) extending from the annular recess (251b) to the shank (251, 1251) and the clamping load is transmitted, in use, to the shank (251, 1251) from the annular spigot (353,

1353) through the annular seat (25 Id) when the assembly is in a molding configuration.

6. A mold assembly (100) according to any one of claims 3 to 5, wherein the core insert (250, 1250) comprises a male taper (253) between the annular recess (251b) and the molding surface (252, 1252) and the split mold insert (350, 1350) comprises a female taper (354b) that abuts the male taper (253) of the core insert (250, 1250) when the stripper plate assembly (300) is in the first position.

7. A mold assembly (100) according to claim 6, wherein the split mold insert (350, 1350) comprises a molding surface (354a) and the female taper (354b) of the split mold insert (350,

1350) is between the annular spigot (353, 1353) and the molding surface (354a) thereof.

8. A mold assembly (100) according to any preceding claim, wherein the annular shoulder (1251c) comprises a cutout (125 le) which is aligned with the air channel (316) to enable the pressurised flow of air (A) to be supplied, in use, before the air channel (316) is clear of the annular shoulder

(251c, 1251c).

9. A mold assembly (100) according to claim 8, wherein the annular shoulder (125 lc) is chamfered to provide the cutout (125 le).

10. A mold assembly (100) according to claim 9, wherein the chamfer (1251e) comprises a flat, substantially planar surface.

11. A mold assembly (100) according to any one of claims 2 to 10, wherein the stripper plate (310) comprises a core aperture (313) through which the core insert (250, 1250) extends, the air channel (316) being described at least partially within the stripper plate (310) and the outlet (316a) is within or adjacent the core aperture (313).

12. A mold assembly (100) according to claim 11, wherein the air channel (316) is angled toward the molding surface (252, 1252) of the core insert (250, 1250).

13. A mold assembly (100) according to claim 11 or claim 12 comprising a bearing plate (315, 1315) between the stripper plate (310) and the slides (320a, 320b) and describing at least part of the air channel (316).

14. A mold assembly (100) according to claim 13, wherein the bearing plate (1315) comprises a core aperture (1317) aligned with the core aperture (313) of the stripper plate (310) and through which the core insert (250, 1250) extends, the bearing plate (1315) comprising an air passage cutout (1316) adjacent the core aperture (1317) and aligned with the air channel (316) of the stripper plate (310).

15. A mold assembly (100) according to any preceding claim, wherein at least part of the annular spigot (353, 1353) has a substantially cylindrical inner surface (354c).

16. A mold assembly (100) according to any preceding claim, wherein at least part of the annular spigot (353, 1353) has a substantially cylindrical outer surface.

17. A mold assembly (100) according to any preceding claim comprising: a plurality of core inserts (250, 1250) mounted to the core plate (210), each core insert (250, 1250) having a molding surface (252, 1252), a shank (251, 1251) and an annular shoulder (251c, 1251c) therebetween; and a plurality of split mold inserts (350, 1350) movably mounted to a stripper plate (310) of the stripper plate assembly (300), each split mold insert (350, 1350) comprising an annular spigot (353, 1353) that engages the annular shoulder (251c, 1251c) of one of the core inserts (250, 1250) for transmitting a clamping load to the shank (251, 1251) when the assembly is in a molding configuration; wherein the stripper plate assembly (300) comprises a plurality of air channels (316) and is movable along the core inserts (250, 1250) from the first position, in which the annular spigot (353, 1353) of each split mold insert (350, 1350) abuts the annular shoulder (251c, 1251c) of its respective core insert (250, 1250) and an outlet (316a) of each air channel (316) is obstructed by the shank (251, 1251) of one of the core inserts (250, 1250), to the second position, in which the outlet (316a) of each air channel (316) is clear of the shank (251, 1251) for supplying, in use, a pressurised flow of air (A) toward the molding surface (252, 1252) of one of the core inserts (250, 1250).

18. A mold assembly (100) according to claim 17, wherein the stripper plate assembly (300) comprises a plurality of slide pairs (320) carrying the split mold inserts (350, 1350), the slides (320a, 320b) having recesses (321) within which the annular spigots (353, 1353) of the split mold inserts (350, 1350) are received and the length of the annular spigots (353, 1353) is equal to or less than the depth of the slides (320a, 320b) such that the annular spigots (353, 1353) are spaced from the stripper plate (310).

19. A mold assembly (100) according to claim 17 or claim 18, wherein the annular shoulder (251c, 125 lc) of each core insert (250, 1250) is provided by a radial step between the shank (251, 1251) and an annular recess (25 lb), the annular spigot (353, 1353) of each split mold insert (350, 1350) being received within the annular recess (251b) of one of the core inserts (250, 1250) when the stripper plate assembly (300) is in the first position and the outlet (316a) of each air channel (316) is aligned with the annular recess (251b) of one of the core inserts (250, 1250) when the stripper plate assembly (300) is in the second position.

20. A mold assembly (100) according to any one of claims 17 to 19, wherein the stripper plate (310) comprises a plurality of core apertures (313) through which the core inserts (250, 1250) extend, each air channel (316) being described at least partially within the stripper plate (310) and each outlet (316a) being within or adjacent one of the core apertures (313).

21. A mold assembly (100) according to any preceding claim, wherein the or each air channel (316) is one of a pair of air channels (316) associated with the or each core insert (250, 1250), each air channel (316) of each pair being located on one side of the or each core insert (250, 1250).

22. A mold assembly (100) according to claim 21, wherein the annular shoulder (251c, 1251c) of the or each core insert (250, 1250) comprises aflat, substantially planar chamfer surface (125 le) aligned with each air channel (316) to enable the pressurised flow of air (A) to be supplied, in use, before the air channel (316) is clear of the annular shoulder (251c, 1251c).

23. A mold assembly (100) according to any preceding claim comprising one or more cavity inserts (440) each having a molding surface (448) and a female taper (447); and a cavity plate (410) to which the or each cavity insert (440) is mounted; wherein the or each split mold insert (350, 1350) comprises a male taper (352) that abuts the female taper (447) of the or one of the cavity insert(s) (440) when the assembly is in the molding configuration.

24. A molding system for molding tubular articles (P), the system comprising a mold assembly (100) according to any preceding claim.

25. A valve mechanism for introducing a pressurised flow of air (A) toward a molded article (P) as it is ejected from a core insert (250, 1250), the valve mechanism comprising a core insert (250, 1250) and a stripper plate (310), the core insert (250, 1250) comprising a molding surface (252, 1252), a shank (251, 1251), a male taper (253) between the molding surface (252, 1252) and the shank (251, 1251) and an annular shoulder (251c, 1251c) between the male taper (253) and the shank (251, 1251), the stripper plate (310) comprising a core aperture (313) and an air channel (316) with an outlet (316a) in or adjacent the core aperture (313), wherein the core insert (250, 1250) is received within the core aperture (313) of the stripper plate (310) and is movable from a closed position, in which the outlet (316a) of the air channel (316) is obstructed by the shank (251, 1251) of the core insert (250, 1250), to an open position, in which the outlet (316a) of the air channel (316) is clear of the shank (251, 1251) and supplies, in use, a pressurised flow of air (A) toward the molding surface (252, 1252) of the core insert (250, 1250).

26. A valve mechanism according to claim 25, wherein the annular shoulder (251c, 1251c) of the core insert (250, 1250) is provided by a radial step between the shank (251, 1251) and an annular recess (251b).

27. A valve mechanism according to claim 26, wherein the outlet (316a) of the air channel (316) is aligned with the annular recess (251b) when the stripper plate assembly (300) is in the second position. 28. A split mold insert (350, 1350) for use in a mold for molding tubular articles (P), the split mold insert (350, 1350) comprising mounting flanges for mounting each part (350a, 350b, 1350a, 1350b) of the split mold insert (350, 1350) to a slide (320a, 320b), an annular male taper (352) on a first side of the mounting flanges for engaging a female taper (447) of a cavity insert (440) and an annular spigot (353, 1353) on a second side of the mounting flanges for engaging the annular shoulder (251c, 1251c) of a core insert (250, 1250), wherein the split mold insert (350,

1350) describes a molding surface (354a) at least partially within the male taper (352) and a female taper (354b) extending from the molding surface (354a) for engaging a male taper (253) of a core insert (250, 1250). 29. A split mold insert (350, 1350) according to claim 28, wherein at least part of the annular spigot

(353, 1353) has a substantially cylindrical inner surface (354c).

30. A split mold insert (350, 1350) according to claim 28 or claim 29, wherein at least part of the annular spigot (353, 1353) has a substantially cylindrical outer surface.

31. A computer program element describing a three-dimensional design for use with a three- dimensional additive or subtractive manufacturing system, the three-dimensional design comprising a split mold insert (350, 1350) according to any one of claims 28 to 30. 32. A core insert (1250) for use in a mold for molding tubular articles, the core insert (1250) comprising a molding surface (1252), a shank (1251) and an annular shoulder (1251c) therebetween, wherein the annular shoulder (1251c) comprises a cutout (125 le) extending into the shank (1251). 33. A core insert (1250) according to claim 32, wherein the cutout (125 le) comprises a flat, substantially planar chamfer surface.

34. A core insert (1250) according to claim 33, wherein the annular shoulder (1251c) comprises a further cutout (125 le) comprising a flat, substantially planar chamfer surface.

35. A computer program element describing a three-dimensional design for use with a three- dimensional additive or subtractive manufacturing system, the three-dimensional design comprising a core insert (250, 1250) according to any one of claims 32 to 34.

36. A bearing plate (1315) for use in a mold for molding tubular articles (P), the bearing plate comprising one or more core apertures (1317) each having at least one air channel cutout (1316) projecting from the core aperture (1317).

37. A computer program element describing a three-dimensional design for use with a three- dimensional additive or subtractive manufacturing system, the three-dimensional design comprising a bearing plate (1315) according to claim 36.

38. A method of designing a mold assembly (100) according to any one of claims 1 to 23, the method comprising selecting the length of the shank (251, 1251) of the core insert (250, 1250) and the length of the spigot (353, 1353) of the split mold insert (350, 1350) based at least in part on the shape of the tubular article (P) to be molded by the mold assembly.

39. A method of ejecting a tubular article (P) from a mold core insert (250, 1250), the method comprising moving a stripper plate assembly (300) relative to a core plate (210) from a first position, in which an annular spigot (353, 1353) of a split mold insert (350, 1350) of the stripper plate assembly (300) abuts the annular shoulder (251c, 1251c) of a core insert (250, 1250) of the core plate assembly (200) and an outlet (316a) of an air channel (316) of the stripper plate assembly (300) is obstructed by the shank (251, 1251) of the core insert (250, 1250), to an second position, in which the outlet (316a) of the air channel (316) is clear of the shank (251, 1251) and supplies a pressurised flow of air (A) toward a molding surface (252, 1252) of the core insert (250, 1250).

40. A method according to claim 39, wherein the outlet (316a) of the air channel (316) is aligned with an annular recess (251b) forming, with the shank (251, 1251), the annular shoulder (251c, 1251c) of the core insert (250, 1250) when the stripper plate assembly (300) is in the second position.

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 stmcture), 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. Traditionally, split mold inserts (sometimes referred to by those skilled in the art as "neck ring") have been 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. As such, 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. It is also known to provide air channels within the molding insert stack adjacent the neck region. These air channels are configured to direct streams of pressurised air toward the molded article during appropriate parts of the molding cycle. In typical configurations, the stream of pressurised air is directed toward the molded article, specifically a rim of the neck region. This stream of pressurised air can perform several functions, such as assisting in the removal of the molded article from the core insert, preventing vacuum build-up or friction between the molded article and the core insert and assisting in the transfer of the molded article into the downstream handling device.

Typically, these air channels are formed at least in part within the core or between the core and a lock ring or stripper ring surrounding the core. This configuration ensures that the stream of pressurised air can be introduced at the appropriate point in the ejection cycle. However, these air channels are normally incorporated within shutoff faces between these components and the split mold insert pair. As such, they are prone to clogging if the mold is flashed and the effective area of the shutoff face is reduced, which can lead to premature wear.

SUMMARY OF THE INVENTION

The present invention seeks to provide an alternative means of assisting the ejection of molding articles, specifically but not exclusively tubular articles such as preforms. This invention is directed, in particular but not exclusively, to mold stacks and components thereof, molds, mold assemblies, molding systems and associated methods. In the case of tubular articles such as preforms, the articles may have a base portion at a closed end, a neck finish at an open end and a body portion therebetween. The neck finish may include one or more radial flanges, which may extend outwardly. The neck finish may include engaging features, such as threads or a snap fit finish. The preform and/or neck finish 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 assembly, e.g. for molding tubular articles such as preforms, the assembly comprising: a core insert with a molding surface, a shank and an annular shoulder therebetween; a core plate to which the core insert is mounted; a split mold insert with an annular spigot that engages the annular shoulder of the core insert for transmitting a clamping load to the shank when the assembly is in a molding configuration; and a stripper plate assembly to which the split mold insert is movably mounted, the stripper plate assembly comprising an air channel with an outlet; wherein the stripper plate assembly is movable along the core insert from a first position, in which the annular spigot of the split mold insert abuts the annular shoulder of the core insert and the outlet of the air channel of the stripper plate assembly is obstructed by the shank of the core insert, to a second position, in which the outlet of the air channel is clear of the shank and/or annular shoulder and supplies, in use, a pressurised flow of air toward the molding surface of the core insert.

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. The split mold insert may comprise two or more parts, e.g. halves. Each part may comprise part of the annular spigot and/or may be mounted to a respective one of the slides. Each slide may have a recess, e.g. within which part of the annular spigot may be received. The or each annular spigot may have a length, e.g. along an axis of the core. The slides may have a depth, e.g. along the axis of the core. The length of the annular spigot may be less than the depth of the slides, e.g. such that the annular spigot is spaced from the stripper plate. The length of the or each annular spigot may be less than the depth of the slides such that the or each annular spigot is spaced from the stripper plate. The length of the or each annular spigot may be between 10% and 90%, e.g. between 20% and 80%, of the depth of the slides. The length of the or each annular spigot is preferably between 25% and 75% of the depth of the slides.

Alternatively, the length of the annular spigot may be longer than, or substantially equal to, the depth of the slides. The shank and/or annular shoulder of the core insert may be received by or within the recess of the or one of the slides, e.g. such that the annular shoulder is recessed with respect to the mounting surface, for example when the assembly is in a molding configuration.

According to another broad aspect of the invention, there is provided a mold assembly, e.g. for molding tubular articles such as preforms, the assembly comprising a core plate assembly and a stripper plate assembly, the core plate assembly comprising a core plate and a core insert mounted to the core plate and having a molding surface, a shank and an annular shoulder therebetween, the stripper plate assembly comprising an air channel with an outlet, a stripper plate, a pair of slides movably mounted to the stripper plate and a split mold insert having two parts each of which is mounted to a mounting surface of a respective one of the slides, each slide having a recess within which the annular shoulder of the core insert is received such that the annular shoulder is recessed with respect to the mounting surface when the assembly is in a molding configuration, wherein the stripper plate assembly is movable along the core insert from a first position, in which an outlet of the air channel of the stripper plate assembly is obstructed by the shank of the core insert, to a second position, in which the outlet of the air channel is clear of the shank and/or annular shoulder and supplies, in use, a pressurised flow of air toward the molding surface of the core insert.

The core insert may comprise an annular recess. The annular shoulder of the core insert may comprise or be provided by a radial step, which may be between the shank and the annular recess. The annular spigot of the split mold insert may be received within the annular recess, for example when the stripper plate assembly is in the first position, e.g. such that part of the shank of the core insert is received within the recesses of the slides. The outlet of the air channel may be aligned with the annular recess, e.g. when the stripper plate assembly is in the second position.

The annular shoulder or radial step may describe an annular seat, which may extend from the annular recess to the shank. The clamping load may be transmitted, in use, to the shank from the annular spigot through the annular seat, e.g. when the assembly is in a molding configuration. The radial step or annular seat may be substantially flat, e.g. from the shank to the annular recess. The radial step or annular seat may be configured to provide a continuous flat surface, e.g. perpendicular to a clamping load applied thereto by the annular spigot of the split mold insert.

The core may comprise a male taper, which may be on its external surface and/or between the annular recess and the molding surface. The split mold insert may comprise a female taper, which may abut the male taper of the core insert, e.g. when the stripper plate assembly is in the first position. The split mold insert may comprise a molding surface. The female taper of the split mold insert may be between the annular spigot and the molding surface thereof.

The annular shoulder may comprise a cutout, which may be aligned with the air channel, for example to enable the pressurised flow of air to be supplied, in use, before the air channel is clear of the annular shoulder. The annular shoulder may be chamfered, for example to provide the cutout. The chamfer may comprise a flat and/or substantially planar surface. The annular shoulder may comprise a flat and/or substantially planar cutout, chamfer, surface or chamfer surface, for example to enable the pressurised flow of air to be supplied, in use, before the air channel is clear of the annular shoulder. The stripper plate may comprise a core aperture, for example through which the core insert may extend. The air channel may be described at least partially within the stripper plate. The outlet may be within or adjacent the core aperture. The air channel may be angled toward the molding of the core insert. The air channel may lie at a non-zero angle relative to an axis of the core.

The mold assembly may comprise a bearing plate. The bearing plate may be between the stripper plate and the slides. The bearing plate may describe at least part of the air channel. The bearing plate may comprise a core aperture, which may be aligned with the core aperture of the stripper plate. The core insert may extend in, through or within the core aperture. The bearing plate may comprise an air passage cutout, which may be adjacent or form part of the core aperture. The air passage cutout may be aligned with the air channel, e.g. the outlet of the air channel, of the stripper plate. Alternatively, the air passage cutout may be omitted or have a different shape. The core aperture may be large enough and/or have a shape or configuration, e.g. to avoid interfering with the air channel of the stripper plate. The core aperture may be elliptical, oval, polygonal or any other suitable shape or configuration.

In some examples, the stripper plate assembly may comprise two or more, e.g. a plurality of air channels adjacent one another. In such examples, each air channel may be angled differently, e.g. may be or lie at a different angle, e.g. non-zero angle, relative to the axis of the core. In such an arrangement, the air blow function may include two or more stages. For example, a flow of pressurized air may be introduced into a first of the adjacent air channels at a first stage and/or a flow of pressurized air may be introduced into a second of the adjacent air channels at a second stage. The adjacent air channels may share an outlet or may comprise respective outlets adjacent one another. In cases where the adjacent air channels have respective outlets, the air passage cutout may be aligned with both air channels, e.g. the outlets of the air channels, of the stripper plate.

At least part of the annular spigot may have a substantially cylindrical inner surface. Additionally or alternatively, at least part of the annular spigot may have a substantially cylindrical outer surface. Each part of the split mold insert may comprise part of the molding surface and/or female taper and/or substantially cylindrical inner and/or outer surfaces.

The mold assembly may comprise a plurality of core inserts, which may be mounted to the core plate. Each core insert may comprise any one or more core insert features described above. Each core insert may have a molding surface and/or a shank and/or an annular shoulder, e.g. between the molding surface and the shank. The mold assembly may comprise a plurality of split mold inserts, which may be movably mounted to the stripper plate assembly. Each split mold insert may comprise any one or more split mold insert features described above. Each split mold insert may comprise an annular spigot, which may engage the annular shoulder of one of the core inserts, e.g. for transmitting a clamping load to the shank, for example when the assembly is in a molding configuration.

The stripper plate assembly may comprise a plurality of air channels. Each air channel may comprise any one or more air channel features described above. The stripper plate assembly may be movable, e.g. along the core inserts, from the first position to a second position. The annular spigot of each split mold insert may abut the annular shoulder of its respective core insert in the first position. An outlet of each air channel may be obstructed by the shank of one of the core inserts in the first position. The outlet of each air channel may be clear of the shank and/or annular shoulder and/or supply, in use, a pressurised flow of air, e.g. toward the molding surface of one of the core inserts, in the second position.

The stripper plate assembly may comprise a plurality of slide pairs, which may carry the split mold inserts. Each slide pair may comprise any one or more slide features described above. The slides may have recesses. The annular spigots of the split mold inserts may be received by or within the recesses of the slide pairs. The shanks and/or annular shoulders of the core inserts may be received by or within the recesses of the slide pairs, e.g. such that each annular shoulder is recessed with respect to the mounting surface, for example when the assembly is in a molding configuration. The length of the annular spigots may be equal to or less than the depth of the slides, e.g. such that the annular spigots are spaced from the stripper plate.

Each core insert may comprise an annular recess. The annular shoulder of each core insert may be provided by a radial step, e.g. between the shank and an annular recess. The annular spigot of each split mold insert may be received within the annular recess of one of the core inserts, e.g. when the stripper plate assembly is in the first position. The outlet of each air channel may be aligned with the annular recess of one of the core inserts, e.g. when the stripper plate assembly is in the second position.

The or each core insert may comprise a single or unitary body, which may include the molding surface and/or the shank and/or the annular shoulder and/or the annular recess and/or the radial step and/or the male taper. The or each split mold insert part or half may comprise a single or unitary body, which may include the mounting flange and/or spigot part and/or male taper part and/or female taper part and/or molding surface part.

The stripper plate may comprise a plurality of core apertures, e.g. through which the core inserts extend. Each core aperture may comprise any one or more core aperture features described above. Each air channel may be described at least partially within the stripper plate. Each outlet may be within or adjacent one of the core apertures.

The or each air channel may be one of a pair of air channels, e.g. associated with the or each core insert. Each air channel of each pair of air channels may be located on one side of the or each core insert. The annular shoulder of the or each core may comprise a pair of cutouts, each of which may be aligned with one of the air channel, for example to enable the pressurised flow of air to be supplied, in use, before the air channel is clear of the annular shoulder. The annular shoulder of the or each core may be chamfered, for example to provide each cutout. Each chamfer may comprise a flat and/or substantially planar surface. The annular shoulder of the or each core may comprise a pair of flat and/or substantially planar cutouts, chamfers, surfaces or chamfer surfaces, for example to enable the pressurised flow of air to be supplied, in use, before the air channels are clear of the annular shoulder.

The annular shoulder of the or each core may comprise a flat, substantially planar chamfer surface aligned with each air channel to enable the pressurised flow of air to be supplied, in use, before the air channel is clear of the annular shoulder. Alternatively, the cutout may be non-flat and/or non- planar. The cutout may comprise a scalloped portion of the shoulder and/or shank. Other configurations of the cutout are also envisaged.

The bearing plate may describe at least part of each air channel. The bearing plate may comprise two or more, e.g. a pair of, air passage cutouts, which may be adjacent or form part of the core aperture. Each air passage cutout may be aligned with one of the air channels of the stripper plate. Alternatively, the air passage cutout may be omitted or have a different shape. The core aperture may be large enough and/or have a shape or configuration, e.g. to avoid interfering with the air channels of the stripper plate. The core aperture may be elliptical, oval, polygonal or any other suitable shape or configuration. The mold assembly may comprise one or more cavity inserts, e.g. a plurality of cavity inserts. The or each cavity insert may have a molding surface and/or a female taper. The mold assembly may comprise a cavity plate, for example to 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 or each split mold insert may comprise a male taper, which may abut the female taper of the or one of the cavity insert(s), e.g. when the assembly is in the molding configuration. Each part of the or each split mold insert may comprise part of the male taper.

The mold assembly may comprise a mold stack, which may be configured to describe a cavity for molding a tubular article when the assembly is in the molding configuration. The mold stack may include the core insert and the split mold insert. The mold stack may also include the cavity insert and/or the gate insert. The mold assembly may comprise a mold base, e.g. a first mold base which may include the core plate and/or the stripper plate. The mold assembly may comprise a second mold base. The mold base or second mold base may include the cavity plate.

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). In some examples, at least part of at least one of the air channels is described at least in part by or within the or one of the wear surface(s) or plate(s). The or each air channel may be directed or angled toward the or one of the core aperture(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 or stripper plate assembly may comprise a guide for guiding the movement of the or each slide pair. The guide may comprise one or more cams, e.g. an upper and a lower cam. The or each cam may comprise a plate with one or more slots formed therein or a profiled member. The slides may comprise one or more cam followers, e.g. for cooperating with the cam(s) as the stripper plate assembly is moved between the first position and the second position. The first position may correspond substantially to the molding configuration of the stripper plate assembly. The second position may correspond substantially to an ejection configuration.

The guide may be configured to separate the slides of the or each slide pair, e.g. as the stripper plate assembly is moved from the first position to the second position or from the molding configuration to the ejection configuration. The guide may be configured to cause each slide of the or each slide pair to separate or move apart or away from one another, e.g. as the stripper plate assembly is moved from the first position to the second position or from the molding configuration to the ejection configuration. The guide may be configured to cause each slide of the or each slide pair to approach one another, e.g. as the stripper plate assembly is moved from the second position to the first position or from the ejection configuration to the molding configuration.

In some examples, a connection is provided between one of the slides of each of a plurality of slide pairs, e.g. such that the connected slides move together in unison. In some examples, a connection is provided between the other slide of each of the plurality of slide pairs such that the plurality of slide pairs move toward or away from one another in unison. The connection may be provided by a connecting bar. In such examples, the movement of the plurality of slide pairs may be guided by a common guide.

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 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 wear plate(s) may be mounted between the cavity facing side of the stripper plate and the slides. The slides may be mounted between the split mold insert(s) and the wear plate(s) or stripper plate. The male taper of the split mold insert(s) may be on the cavity facing side of the 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 broad aspect of the invention provides a mold assembly for molding tubular articles, the assembly being movable between a molding configuration and a demolding configuration and comprising: a core plate to which is mounted at least one core insert having a molding surface, an annular shoulder and a male taper between the molding surface and the annular shoulder; a cavity plate to which is mounted at least one cavity insert with a female taper; a stripper plate assembly to which is movably mounted at least one split mold insert pair that together describe a male taper, which engages the female taper of the cavity insert in the molding configuration, and an annular spigot, which engages the annular shoulder of the core insert in the molding configuration; wherein the stripper plate assembly comprises an air channel, which directs, in use, a pressurised flow of air toward a molded article in the demolding configuration but is obstructed by the annular shoulder of the core insert in the molding configuration.

Another broad aspect of the invention provides a mold for molding preforms, comprising: a first mold part that includes a first mold base; a second mold part that includes a second mold base; a mold stack having mold inserts disposed on the first and second mold bases with which to define a molding cavity when the first and second mold parts are arranged in a molding configuration; the mold stack assembly includes a core insert and a split mold insert both associated with the first mold part and a cavity insert associated with the second mold part; the first mold base includes a stripper plate assembly having a stripper plate with slides moveably connected on a face thereof; the first mold base also includes a core plate assembly having a core plate with the core insert connected thereto; the split mold insert includes at least two neck parts connected to the slides, the neck parts surround and otherwise cooperate with the core insert in the molding configuration to define part of the molding cavity; the split mold insert includes an annular spigot and the core insert includes an annular seat, the annular spigot of the split mold insert is receivable on the annular seat of the core in the molding configuration for transferring an applied clamp load therethrough; the stripper plate defines a transfer air channel with an outlet inclined towards a tip of the core; an outlet of the air channel is obstructed by a shank of the core insert that is behind the annular seat when the mold stack is in the molding configuration; the outlet of the air channel is unobstructed by the shank of the core insert for dispensing air between the slides and neck parts of the split mold inserts in an ejection configuration that results from movement of the stripper plate assembly relative to the core plate assembly.

Another broad aspect of the invention provides a molding system, e.g. for molding tubular articles. The system may comprise a mold assembly as described above. The system may comprise a machine, e.g. an injection molding machine, to or within which the mold assembly may be mounted. The machine may be configured or operable to mold tubular articles, e.g. preforms, using the mold assembly.

Another broad aspect of the invention provides a valve mechanism, e.g. for introducing a pressurised flow of air toward a molded article as it is ejected from a core insert, the valve mechanism comprising a core insert and a stripper plate, the core insert comprising a molding surface, a shank, a male taper between the molding surface and the shank and an annular shoulder between the male taper and the shank, the stripper plate comprising a core aperture and an air channel with an outlet in or adjacent the core aperture, wherein the core insert is received within the core aperture of the stripper plate and is movable from a first or closed position, in which the outlet of the air channel is obstructed by the shank of the core insert, to a second or open position, in which the outlet of the air channel is clear of the shank and/or annular shoulder and supplies, in use, a pressurised flow of air toward the molding surface of the core insert.

The annular shoulder of the core insert may be provided by a radial step between the shank and an annular recess. The outlet of the air channel may be aligned with the annular recess, e.g. when the stripper plate assembly is in the second position.

Another broad aspect of the invention provides a split mold insert, e.g. for use in a mold for molding tubular articles such as preforms, the split mold insert comprising one or more mounting flanges for mounting the, or each part of the, split mold insert to a slide, an annular male taper on a first side of the mounting flange(s), e.g. for engaging a female taper of a cavity insert, and an annular spigot on a second side of the mounting flange(s), e.g. for engaging the annular shoulder of a core insert, wherein the split mold insert describes a molding surface at least partially within the male taper and a female taper extending from the molding surface for engaging a male taper of a core insert.

At least part of the annular spigot may have a substantially cylindrical inner surface. Additionally or alternatively, at least part of the annular spigot has a substantially cylindrical outer surface.

Another aspect of the invention provides a core insert, e.g. for use in a mold for molding tubular articles such as preforms, the core insert comprising a molding surface, a shank and an annular shoulder therebetween, wherein the annular shoulder comprises a cutout, which may extend into the shank.

The annular shoulder may comprise a further, e.g. second, cutout. The annular shoulder may comprise a pair or a plurality of cutouts. The or each cutout may be provided by a chamfer in or of the shoulder and/or the shank. The annular shoulder may be chamfered, for example to provide the cutout(s). The or each chamfer may comprise a flat and/or substantially planar surface. The annular shoulder may comprise one or more, e.g. a pair of, flat and/or substantially planar cutout(s), chamfer(s), surface(s) or chamfer surface(s).

The core insert may comprise any one or more additional features described above in relation to the core insert of the mold assembly or mold or valve mechanism.

Another aspect of the invention provides a bearing or wear plate, e.g. for use in a mold for molding tubular articles such as preforms, the bearing plate comprising one or more core apertures each having at least one air channel cutout, e.g. projecting from the core aperture.

The bearing or wear plate may comprise any one or more additional features described above in relation to the bearing plate of the mold assembly or mold or valve mechanism.

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.

Another broad aspect of the invention provides a method of designing a mold assembly, e.g. as described above, the method comprising selecting the length of the shank of the core and/or the length of the spigot of the split mold insert based at least in part on the shape of the tubular article to be molded by the mold assembly.

Another broad aspect of the invention provides a method of ejecting an article, e.g. a tubular article, from a mold core insert, the method comprising moving a stripper plate assembly relative to a core plate from a first position, in which an annular spigot of a split mold insert of the stripper plate assembly abuts the annular shoulder of a core insert of the core plate assembly and an outlet of an air channel of the stripper plate assembly is obstructed by the shank of the core insert, to an second position, in which the outlet of the air channel is clear of the shank and/or annular shoulder and supplies a pressurised flow of air toward a molding surface of the core insert.

The outlet of the air channel may be aligned with an annular recess of the core insert, e.g. when the stripper plate assembly is in the second position. The annular recess may form, with the shank, the annular shoulder of the core insert. The outlet of the air channel may pass the annular shoulder of the core insert, e.g. as the stripper plate assembly moves from the first position to the second position. The stripper plate assembly may be movable from the first position to the second position via an intermediate position, e.g. at which the outlet of the air channel is aligned with the annular shoulder of the core insert.

Another aspect of the invention provides a method of assembling a mold assembly or mold as described above. Various steps and features of the method will be apparent to the skilled person.

Another aspect of the invention provides a method of molding articles. The method may comprise the use of one of the aforementioned mold stacks, molds, mold assemblies or molding systems. The method may comprise any one or more features or steps relevant to or involving the use of any feature of any of the aforementioned mold stacks, molds, mold assemblies or molding systems. 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 preform mold assembly according to an embodiment of the invention;

FIG. 2 depicts a partial section view through a mold stack of the mold of FIG. 1, with the melt distributor, core plate and core cooling tube omitted; FIG. 3 depicts a mold core of the mold assembly of FIGs. 1 and 2;

FIG. 4 depicts three neck ring halves of the mold assembly of FIGs. 1 and 2;

FIG. 5 depicts the moving part of the preform mold assembly of FIG. 1, including the core plate assembly and stripper plate assembly;

FIG. 6 depicts a partial section view through a mold stack of the moving part of FIG. 5 in an ejection configuration, with the core plate and core cooling tube omitted; FIG. 7 depicts a partial section view through a mold stack of the moving part of another example shown in an ejection configuration, with the core plate and core cooling tube omitted; FIG. 8 depicts the mold core of the mold stack of FIG. 7;

FIG. 9 depicts a plan view of the stripper plate of the mold stack of FIG. 7; and FIG. 10 depicts an enlarged view of region R of the stripper plate of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, there is depicted a non-limiting embodiment of a preform mold assembly 100 according to the invention, which includes forty-eight cavities in this embodiment. The mold assembly 100 includes a first, moving part 110 for mounting to the moving platen (not shown) of an injection molding machine (not shown) and a second, stationary part 120 for mounting to the stationary platen (not shown) in the usual way. The first, moving part 110 includes a core plate assembly 200 and a stripper plate assembly 300. The second, stationary part 120 includes a cavity plate assembly 400 and a melt distributor 500, commonly referred to as a hot runner. In this embodiment, the melt distributor 500 is of a conventional type. This invention is particularly concerned with the product specific assembly 130, commonly referred to as the ‘cold half’ 130. The cold half 130 includes the core plate assembly 200, stripper plate assembly 300 and cavity plate assembly 400. A plurality of mold stacks MS are provided, one of which is illustrated in FIG. 2 in a molding configuration. More particularly, the core plate assembly 200 includes a core plate 210 having plurality of cores 250, the stripper plate assembly 300 includes a plurality of split mold inserts 350 and the cavity plate assembly 400 includes a plurality of cavity assemblies 430. Each mold stack MS is provided by one of each of the cores 250, split mold inserts 350 and cavity assemblies 430. Each split mold insert 350, commonly referred to as a neck ring 350, includes two halves 350a, 350b in the usual way. However, the invention is not so limited; the split mold inserts 350 could include more than two parts. Each cavity assembly 430 includes a cavity insert 440 and a gate insert 450. Each core insert 250, illustrated in FIG. 3, includes a substantially cylindrical base 251 and a molding portion 252 joined to the base 251 by a taper 253. The base 251 includes a shank portion 251a, an annular recess 251b and an annular shoulder 251c formed by a radial step between the shank portion 251a and the annular recess 251b. An annular seat 25 Id is also described by the radial step, which extends from the annular recess 251b to the shank portion 251a and lies in a radial plane. The outer surface of the molding portion 252 forms, during the molding operation, an inner surface of a preform P in the usual way. The core taper 253 extends from the top sealing surface portion of the preform P to the base 251 to provide a stack configuration known in the art as a so-called ‘cavity-lock’ design.

Each core insert 250 is hollow and includes a central bore 250a extending from a mounting surface 254 to a hemispherical or domed, closed end adjacent the free end of the molding portion 252. The central bore 250a extends from an open end at the mounting surface 254, along the base 251 and follows a similar profile to the outer surface of the molding portion 252 such that the wall thickness of the hollow core remains substantially constant along the entire molding portion 252.

Each neck ring 350, illustrated in FIG. 4, is formed of a pair of neck ring halves 350a, 350b. Each neck ring half 350a, 350b includes a mounting flange 351, an annular male taper 352 on a first side of the mounting flange 351 and an annular spigot 353 on a second side of the mounting flange 351. Each neck ring half 350a has a semi-cylindrical recess which together describe a cylindrical central opening 354 extending through the male taper 352, mounting flanges 351 and annular spigot 353, when the neck ring halves 350a, 350b are brought together during operation of an injection molding system.

The central opening 354 of each neck ring 350 includes a molding surface 354a for a neck region of a preform P to be molded, a female taper surface 354b and a cylindrical surface 354c. Each mounting flange 351 has a pair of longitudinally opposed, generally stepped, semi-cylindrical side apertures 355. Each aperture 355 has a passageway that extends all the way through the mounting flange 351 of the neck ring half 350a, 350b. When a pair of neck ring halves 350a, 350b are positioned longitudinally adjacent to each other, a cylindrical opening is formed by the two adjacent, facing apertures 355 to receive a mounting bolt. This enables each neck ring half 350a, 350b of one neck ring 350 to share a mounting bolt with an adjacent neck ring half 350a, 350b of another neck ring 350, thereby enabling a smaller pitch distance than is conventional. The cavity insert 440 includes a substantially cylindrical body 441 and a spigot 443 projecting from one end of the body 441, which is hollow and has a stepped gate insert seat 446 for receiving the gate insert 450. The body 441 of the cavity insert 440 is also hollow and includes a female taper 447 in a second end of the body 441 and a molding surface 448 extending from the female taper 447 to the gate insert seat 446. The spigot 443 also includes a pair of opposed cooling channel slots 448 therein.

The gate insert 450 is substantially cylindrical in shape with a nozzle tip receptacle 451, a hemispherical molding surface 452 and a gate 453 joining the nozzle tip receptacle 451 to the molding surface 452. The nozzle tip receptacle 451 is shaped to accommodate the tip of a valve-gated injection nozzle (not shown) and associated tip insulator (not shown) in the usual way. The molding surface 452 is shaped to describe the outer surface of the base of a preform P to be molded in the usual way. The outer profile of the gate insert 450 is stepped to match the gate insert seat 446 of the cavity insert 440. The gate insert 450 also has a central, circumferential cooling groove 454 aligned with the cooling channel slots 448 in the spigot 443 of the cavity insert 440.

The cavity plate 410 includes a plurality of seats 412 through its thickness and a network of cooling channels 413 in communication with the seats 412. The spigot 443 of each cavity insert 440 is received within one of the seats 412, such that the cooling channel slots 448 of the spigot and the cooling groove 454 of the gate insert 450 are aligned with adjacent cooling channels 413. In this example, the cavity insert 440 and gate insert 450 of the cavity assembly 430 are separate components, but in other variations they may be formed as a single, unitary structure.

In the molding configuration, shown in FIG. 2, the top sealing surface of the preform P is described in part by the molding portion 252 of the core insert 250 and in part by the molding surface 354a of the neck ring 350. The components of each mold stack MS are engaged with one another in what is commonly referred to in the art as a ‘cavity-lock’ design. The female taper surface 354b of the neck ring 350 surrounds the male taper 253 of the core insert 250 and the cylindrical surface 354c of the neck ring 350 lies within the annular recess 251b of the base 251 of the core insert 250 such that the annular spigot 353 abuts the annular seat 25 Id. The annular male taper 352 of the neck ring 350 is also received within and engages the female taper 447 of the cavity insert 440.

Turning now to FIG. 5, the moving part 110 of the mold assembly 100 is shown in isolation, with the cavity plate assembly 400 omitted to expose features of the core plate assembly 200 and the stripper plate assembly 300. The core plate assembly 200 includes the core plate 210, a pair of cam plates 220, four guide pins 230 and the core inserts 250. The core plate 210 is substantially rectangular in plan with scalloped comers 211, for accommodating the debars (not shown) of an injection molding machine (not shown) within which the mold is mounted. The guide pins 230 are secured to, and project from, the core plate 210 adjacent, but horizontally inboard of, each scalloped comer 211. The core plate 210 also includes a plurality of ejector holes 213 (shown in FIG. 1) through its thickness, for accommodating ejector pins (not shown).

One of the cam plates 220 is bolted to a central, upper region of the front of the core plate 210 and includes a pair of cam slots 221 on its lower surface. The other cam plate 220 is bolted to a central, lower region of the front of the core plate 210 and includes a similar pair of cam slots 221 on its upper surface. Both cam plates 220 have the same configuration, varying only in their orientation. The cam slots 221 of each cam plate 220 extend perpendicularly from the core plate 210 and converge toward the free end of the cam plate 220.

The stripper plate assembly 300 includes a stripper plate 310, six slide pairs 320 slidably mounted to the stripper plate 310, upper and lower guide assemblies 330, which guide the movement of the slide pairs 320 along the stripper plate 310 and four connecting bars 340. The neck ring halves 350a, 350b are mounted on the slides 320 for movement therewith. The stripper plate 310 is substantially rectangular in plan with scalloped comers 311, which are aligned with the scalloped corners 211 of the core plate 210 for accommodating the debars (not shown) of an injection molding machine (not shown) within which the mold is mounted. The stripper plate 310 also includes four guide pin bushings 312 with associated holes (not shown) through its thickness, which are horizontally inboard of each scalloped comer 311 for receiving the guide pins 230 of the core plate 210. The stripper plate 310 also includes a plurality of core insert holes 313 through its thickness, upper and lower cam plate holes 314 and wear or bearing plates 315, hereinafter bearing plates 315, which provide bearing surfaces along and against which the slides 320 move on the stripper plate 310.

Each guide pin bushing 312 is in the form of a hollow cylinder, bolted to the stripper plate 310. Each guide pin bushing 312 has an internal diameter, which provides a small gap between it and the guide pin 230 it receives within which grease is received. As a result, the guide pins 230 slide freely within the guide pin bushings 312 to support the stripper plate 310 during movement between it and the core plate 210 in the usual way. Each core insert hole 313 is sized to provide a small clearance between it and the core insert base 251 in order to prevent contact between them as the stripper plate 310 is moved toward and away from the core plate 210 along the guide pins 230.

As illustrated in FIG. 2, a pair of the air channels 316 are formed adjacent each core insert hole 313. One air channel 316 is located on each side of the core insert hole 313, which are angled and converge toward one another to respective outlets 316a at an adjacent edge of the core insert hole 313. As such, the air channels 316 are angled toward the molding portion 252 of the core insert 250. In the molding configuration, shown in FIG. 2, the outlets 316a are obstructed by the shank portion 251a of the core insert 250.

Each slide pair 320, includes first and second slides 320a, 320b, which have essentially the same design. Each slide 320a, 320b is in the form of a bar having a substantially square or near-square cross-section, with a plurality of semi-circular cut-outs or recesses 321 along one of its sides. The neck rings 350 are mounted to the slides 320a, 320b such that the part of the annular spigot 353 described by each of the neck ring halves 350a, 350b is received within one of the recesses 321 of one of the slides 320a, 320b. As shown in FIG. 2, the length of the annular spigot 353 is less than the depth of the slides 320a, 320b, such that the annular spigot 353 is spaced from the stripper plate 310. The annular shoulder 251b, annular seat 25 Id and part of the shank portion 251a of the base 251 of the core insert 250 are also received within each recess 321 of each slide 320a, 320b.

The slides 320a, 320b are movably retained to the stripper plate 310 by the upper and lower guide assemblies 330 and are interconnected by the connecting bars 340. Each end of each slide 320a, 320b receives a round guide shaft 331 mounted to the stripper plate 310 by brackets 332. One of the connecting bars 340 is connected to the first slide 320a of each slide pair 320 and the other of the connecting bars 340 is connected to the second side 320b of each slide pair 320. As such, sliding movement of one of the first slides 320a causes all of the first slides 320a to move therewith. Similarly, sliding movement of one of the second slides 320b causes all of the second slides 320b to move therewith.

The centermost slides 320a, 320b also include a cam follower 324 at each end. Each cam follower 324 is in the form of a roller, which is rotatably received within one of the cam slots 221 of one of the cam plates 220. In use, forward movement of the stripper plate 310 away from the core plate 210 causes the cam followers 324 to move along the cam slots 221, which causes the slides 320a, 320b carrying the cam followers 324 to slide along the guide shafts 331 and bearing plates 315 toward one another. This, in turn, causes the slides 320a, 320b of each slide pair 320 to move away from one another, sliding along the guide shafts 331 and bearing plates 315, to open the neck ring halves 350a, 350b and in so doing eject preforms P from the cores 250 in the usual way. Similarly, rearward movement of the stripper plate 310 towards the core plate 210 causes the cam followers 324 to follow a reverse path along the cam slots 221, thereby closing the neck ring halves 350a, 350b.

Referring now to FIG. 6, the mold stack MS is shown in an ejection configuration in which the core 250 is retracted relative to the stripper plate assembly 300 and the slides 320a, 320b are separated to enable the preform P to be ejected from the core 250 in the usual way. As mentioned above, the outlets 316a of the air channel 316 are obstructed by the shank portion 251a of the core insert 250 when the mold stack MS is in the molding configuration, as shown in FIG. 2. The recesses 321 in the slides 320a, 320b abut the outer surface of the shank portion 251a when the mold stack is in the molding configuration, shown in FIG. 2. This effectively blocks the pressurised air within the air channels 316 from being released.

In the ejection configuration shown in FIG. 6, the outlets 316a of the air channels 316 are clear of the annular shoulder 251c and is aligned with the annular recess 251b. Pressurised air A supplied to the air channels 316 from a pressurised air source (not shown) exits the outlets 316a and is directed toward the molding surface 252 of the core 250. This stream of pressurised air A impacts a rim of the neck region of the preform P, which assists in the transfer of the preform P into the downstream handling device and prevents vacuum build-up or friction between the preform P and the core insert 250.

As such, the slides 320a, 320b act, in conjunction with the shank portion 251a of the core insert 250, as a valve mechanism to selectively block the pressurised air within the air channels 316 from being released. The provision of a spigot 353 on each neck ring 350 displaces the interface between the core 250 and the neck ring 350 to a position closer to the stripper plate 310. The skilled person will appreciate that positioning the air channels 316 in the stripper plate assembly 300, specifically in the stripper plate 310 in this example, precludes the need to include them in the shutoff faces between the cores 250 and neck rings 350. However, the invention enables the time within the ejection cycle at which the pressurised air A is introduced to be similar to that with the aforementioned air channels in the shutoff faces. In the present invention, this, air blow timing is a function of the position of the interface between the core 250 and the neck ring 350, namely the length of the spigot 353. More specifically, the ejection stroke distance (i.e. the distance between the stripper plate 310 and the core plate 210) at which the outlets 316a of the air channels 316 are unobstructed by the shank portion 251a is equivalent to the distance from the stripper plate 310 to the annular shoulder 251c. When the outlet 316a of the air channel 316 is clear of the annular shoulder 251c, the stream of pressurised air A can be introduced.

However, additional advantageous features of the invention, which enable the air blow function to be initiated earlier, can be seen in the alternative stripper plate assembly 1300 illustrated in FIGs. 7 to 9. This stripper plate assembly 1300 is similar to the stripper plate assembly 300 described above, wherein like features are labelled with like references with the addition of a preceding ‘1’. As shown, this stripper plate assembly 1300 differs in that the spigot 1353 of the neck ring halves 1350a, 1350b is much shorter than that of the previous example, the shank portion 1251a includes a pair of chamfers 1251e and the bearing plates 1315 include air passage cutouts 1316 aligned with the outlets 316a of the air channels 316 of the stripper plate 310 and on either side of the cores 1250.

As illustrated in FIG. 8, the chamfers 125 le are flat, angled cutouts on each side of the annular shoulder 1251c. The chamfers 125 le are aligned with the outlets 316a of the air channels 316 of the stripper plate 310, which is clearly seen in FIG. 7. In this example, the chamfers 125 le are angled at 45 degrees relative to the annular seat 125 Id.

As illustrated in FIG. 9, the stripper plate 310 according to this example includes a plurality of core insert holes 313 through its thickness and ten bearing plates 1315 surrounding some, but not all, of the core insert holes 313. The core insert holes 313 are arranged in an array of six vertical columns and four horizontal rows and each is configured to accommodate the base 1251 of one of the core inserts 1250. Each core insert hole 313 is sized to provide a clearance between it and the core insert base 1251 in order to prevent contact between them as the stripper plate 310 is moved toward and away from the core plate 210.

The bearing plates 1315, shown more clearly in FIG. 10, are formed of a wear resistant material. Each bearing plate 1315 is substantially rectangular in plan and includes two holes 1317 through its thickness and four part-circular cut-outs 1317a, 1317b. The pitch spacing of the bearing plate holes 1317 corresponds to the pitch spacing of the core insert holes 313 along each vertical column. Two of the part-circular cut-outs 1317a are at the center of the short edges of the bearing plate 1315 and the pitch spacing of each part-circular cut-out 1317a and its adjacent bearing plate hole 1317 also corresponds to the pitch spacing of the core insert holes 313 along each vertical column. The other two part-circular cut-outs 1317b are at the center of the long edges of the bearing plate 1315. As such, the bearing plates 1315 are symmetrical about a central, longitudinal axis.

The bearing plates 1315 also include a pair of part-circular air passage cutouts 1316 at each side of the holes 1317. The bearing plates 1315 are placed lengthwise along one of the vertical columns, with the bearing plate holes 1317 and part-circular cut-outs 1317a aligned with the core insert holes 313. The air passage cutouts 1316 are aligned with the adjacent outlets 316a of the air channels 316 of the stripper plate 310. Three bearing plates 1315 are mounted along each of the two central columns of core insert holes 313, whilst a single bearing plate 1315 is mounted at the vertical center of the four outermost columns. In the mold 100 according to this disclosure, bearing plates 1315 are selectively positioned to provide balanced support for the slide pairs 320 during ejection, whilst minimising their number to reduce cost. However, it is envisaged that more or less bearing plates 1315 may be used or that a single bearing plate may be provided that covers all of the relevant area of the stripper plate 310.

The stripper plate assembly 1300 shown in FIG. 7 is at a similar ejection position to that shown in FIG. 6, which illustrates clearly that the outlets 316a of the air channels 316 in this position are not yet clear of the annular shoulder 1251c. This will only occur with the stripper plate assembly 1300 at an ejection position that is much further forward. However, it will be appreciated that the air blow function can still be initiated in this position by virtue of the chamfers 125 le in the annular shoulder 1251c, which extend into the shank portion 1251a and the air passage cutouts 1316 of the bearing plates 1315. As such, the air passages 316, which are effectively extended by the air passage cutouts 1316, clear the adjacent parts of the shank portion 1251a by virtue of the chamfers 125 le.

Pressurised air A supplied to the air channels 316 from a pressurised air source (not shown) is therefore able to exit the outlets 316a, pass through the air passage cutouts 1316 of the bearing plates 1315 and pass across the chamfers 125 le of the shank portion 1251a. As illustrated by the arrows in FIG. 7, the stream of pressurised air A exiting from the cutouts 1316 impacts a rim of the neck region of the preform P, which assists in the transfer of the preform P into the downstream handling device and prevents vacuum build-up or friction between the preform P and the core insert 1250, as described above in relation to the stripper plate assembly 300 according to the first example.

It will be appreciated that the angle of the chamfers 125 le may vary from that shown in the drawings, in order to achieve the desired air flow characteristics and/or performance. Similarly, the bearing plates 1315 need not include air passage cutouts 1316 and/or they may have a different shape. In some examples, the holes 1317 of the bearing plates 1315 are simply made large enough or their shape may be modified (e.g. elliptical) to avoid their interference with the flow of air A.

Additionally or alternatively, the stripper plate assembly 300, 1300 may include two or more, e.g. a plurality of air channels 316 adjacent one another. In such examples, each air channel 316 may lie at a different angle relative to the axis of the core insert 250, 1250. In such an arrangement, the air blow function may include two or more stages. For example, a flow of pressurized air may be introduced into a first of the adjacent air channels 316 at a first stage and a flow of pressurized air may be introduced into a second of the adjacent air channels 316 at a second stage. The adjacent air channels may share an outlet 316a or may comprise respective outlets 316a adjacent one another. In cases where the adjacent air channels have respective outlets, the air passage cutout 1316 may be aligned with both outlets 316a.

It will also be appreciated that the spigot 353 of the neck ring 350 can be extended further than in the first example, which will result in the outlets 316a of the air channels 316 clearing the annular shoulder 25 lc even earlier in the ejection cycle. The skilled person will understand that the length of the spigot 353 may be selected to provide the most appropriate air blow timing to suit the specific design of the preform P to be molded.

It will be appreciated that the configuration of the elements of the molding system 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.