CA3192997A1 - Molds, mold assemblies, stack components and molded articles - Google Patents
Molds, mold assemblies, stack components and molded articlesInfo
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- CA3192997A1 CA3192997A1 CA3192997A CA3192997A CA3192997A1 CA 3192997 A1 CA3192997 A1 CA 3192997A1 CA 3192997 A CA3192997 A CA 3192997A CA 3192997 A CA3192997 A CA 3192997A CA 3192997 A1 CA3192997 A1 CA 3192997A1
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- preform
- insert
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- recess
- passage
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Abstract
The invention relates to a mold stack (MS) with a core insert (20) and a gate insert (5) that together describe a closed end (11a, 1 la') of a tubular article (1). The gate insert (5) has a cavity portion (50), a nozzle receiving portion (52) and a passage (53) joining them. The cavity portion (50) has an annular ridge (54) that surrounds and joins it to the passage (53). The ridge (54) has a height (H) that is less than one quarter of a diameter (W4) of the passage (53). The core insert (20) has a truncated end portion aligned with the ridge (54) of the gate insert (5), so that the tubular article (1) has a closed end (11a, 11 a') with an outer surface formed by a truncated dome with a recessed apex (14).
Description
MOLDS, MOLD ASSEMBLIES, STACK COMPONENTS AND MOLDED ARTICLES
FIELD OF THE INVENTION
This invention relates generally to molding apparatus and associated methods and molded articles.
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 and molded tubular articles, such as preforms.
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 blow molded 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 Date Recue/Date Received 2023-03-14 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 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 (ex. a 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 core insert and optionally a gate insert, a lock ring and/or a core ring, 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 cavity insert or 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.
FIELD OF THE INVENTION
This invention relates generally to molding apparatus and associated methods and molded articles.
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 and molded tubular articles, such as preforms.
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 blow molded 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 Date Recue/Date Received 2023-03-14 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 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 (ex. a 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 core insert and optionally a gate insert, a lock ring and/or a core ring, 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 cavity insert or 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.
2 Date Recue/Date Received 2023-03-14 Preforms intended to be blow molded into a container normally include a hollow cylindrical body, typically with a varying thickness and having an open end having the final shape of the bottle neck, and a closed end having a dome shape intended to form a base of the bottle. In the production of plastic bottles, biaxial molecular orientation blow molding, also referred to simply as blow molding, is a widely applied process. This process can either be carried out simultaneously with the injection molding process in an integrated system, commonly referred to as a single stage process, or separately using a so-called two-stage process. In the two-stage process, the preforms are molded in a dedicated injection molding machine, and are subsequently cooled and stored for a predetermined period. These preforms are later heated to a temperature sufficient to soften the body and fed into a stretch blow molding machine.
In the blow molding machine, the hot and deformable preform is placed in a blow-molding cavity, which describes the shape of the body of the final plastic bottle. A stretch rod is inserted into the preform via its open neck, stretches the base of the preform to a closed end of the blow-molding cavity, and a pressurized fluid, normally compressed air, is introduced into the stretched preform to force the stretched preform material against the walls of the blow-molding cavity.
The shape of the cavity varies along its length, creating variations in the extent to which distinct regions of the preform body are stretched. This results in variations in the wall thickness of the finished bottle. One technique for improving material thickness distribution is commonly referred to as "heat profiling". This technique involves varying the temperature to which selected regions within the preform are heated, in order to influence the extent to which these regions stretch during the blow-molding process. More particularly, regions that are hotter than others will deform more readily, so the aim is to align the hotter preform regions with corresponding areas of the bottle which would otherwise tend to have a thicker wall.
However, this technique is less effective in the domed end region of the preform, in part since it has a lower surface to volume ratio. This is particularly true of the region of the gate nub.
W02020006624A1 seeks to mitigate this by providing the closed end of the preform with elliptical inner and outer faces each with a respective flat circular bottom portion, which are both centered on a vertical center axis of the preform and have a radius of equal size. This is believed to improve material distribution in the finished bottle.
In the blow molding machine, the hot and deformable preform is placed in a blow-molding cavity, which describes the shape of the body of the final plastic bottle. A stretch rod is inserted into the preform via its open neck, stretches the base of the preform to a closed end of the blow-molding cavity, and a pressurized fluid, normally compressed air, is introduced into the stretched preform to force the stretched preform material against the walls of the blow-molding cavity.
The shape of the cavity varies along its length, creating variations in the extent to which distinct regions of the preform body are stretched. This results in variations in the wall thickness of the finished bottle. One technique for improving material thickness distribution is commonly referred to as "heat profiling". This technique involves varying the temperature to which selected regions within the preform are heated, in order to influence the extent to which these regions stretch during the blow-molding process. More particularly, regions that are hotter than others will deform more readily, so the aim is to align the hotter preform regions with corresponding areas of the bottle which would otherwise tend to have a thicker wall.
However, this technique is less effective in the domed end region of the preform, in part since it has a lower surface to volume ratio. This is particularly true of the region of the gate nub.
W02020006624A1 seeks to mitigate this by providing the closed end of the preform with elliptical inner and outer faces each with a respective flat circular bottom portion, which are both centered on a vertical center axis of the preform and have a radius of equal size. This is believed to improve material distribution in the finished bottle.
3 Date Recue/Date Received 2023-03-14 The applicants have observed that material distribution can be further improved, whilst further reducing the quantity of wasted material in the gate area.
SUMMARY OF THE INVENTION
The present invention seeks to provide, inter alia, a means by which the distribution of material in the gate area can be improved to increase the proportion of material that is redistributed into the body of a subsequently blown container. 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, and the tubular articles themselves.
The tubular article may have a hollow body portion, which may have a closed end. The tubular article may have a neck portion, which may have an open 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 tubular article 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 preforms may be incorporated within tubular articles according to the invention, insofar as they are consistent with the disclosure herein.
Advantageously, the closed end of the tubular article may be formed by a truncated dome. The truncated dome may have an axial centre that is flush or recessed relative to a surrounding convex surface of the truncated dome. The recess, if present, may have a diameter or width that is at least 10 times its depth.
According to a broad aspect of the present invention, there is provided a tubular article, e.g. a preform for being blow molded into a container, the tubular article comprising a closed end having an outer surface formed by a truncated dome with an axial centre, or apex, that is flush or recessed relative to a surrounding convex surface of the truncated dome, wherein the recess, if present, has a diameter or width that is at least 10 times its depth.
The provision of a closed end with a flush or slightly recessed axial centre, or apex, effectively eliminates the funnel shaped transition between the dome shaped base and the gate nub. This reduces the time needed to cool this area of the tubular article, thereby reducing cycle time. This is also
SUMMARY OF THE INVENTION
The present invention seeks to provide, inter alia, a means by which the distribution of material in the gate area can be improved to increase the proportion of material that is redistributed into the body of a subsequently blown container. 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, and the tubular articles themselves.
The tubular article may have a hollow body portion, which may have a closed end. The tubular article may have a neck portion, which may have an open 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 tubular article 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 preforms may be incorporated within tubular articles according to the invention, insofar as they are consistent with the disclosure herein.
Advantageously, the closed end of the tubular article may be formed by a truncated dome. The truncated dome may have an axial centre that is flush or recessed relative to a surrounding convex surface of the truncated dome. The recess, if present, may have a diameter or width that is at least 10 times its depth.
According to a broad aspect of the present invention, there is provided a tubular article, e.g. a preform for being blow molded into a container, the tubular article comprising a closed end having an outer surface formed by a truncated dome with an axial centre, or apex, that is flush or recessed relative to a surrounding convex surface of the truncated dome, wherein the recess, if present, has a diameter or width that is at least 10 times its depth.
The provision of a closed end with a flush or slightly recessed axial centre, or apex, effectively eliminates the funnel shaped transition between the dome shaped base and the gate nub. This reduces the time needed to cool this area of the tubular article, thereby reducing cycle time. This is also
4 Date Recue/Date Received 2023-03-14 believed to provide a more effective delineation between the gate region and the surrounding material to be heated and stretched, whilst enabling the wall thickness of the gate region at the axial end of the base to be reduced. This is believed to be particularly true with a slightly recessed axial centre, or apex, as the ridge surrounding the recess further exaggerates this delineation. As a result, thermal profiling of the tubular article can be more effective whilst reducing the overall weight of the tubular article.
The tubular article may comprise a witness mark, which may comprise or describe at least part of the flush surface or recess. The flush surface or recess may, but need not, be flat. In some examples, the flush surface or recess may be conical or curved, e.g. spherical. The witness mark may correspond to a surface or portion formed at least in part by a valve stem. The witness mark may comprise a circular indentation or projection. Additionally or alternatively, the witness mark may comprise an annular projection. The witness mark may correspond in part to an outer surface of an end of the valve stem.
The witness mark may correspond at least in part to a passage in a mold insert, e.g. within which the valve stem was received and/or through which the valve stem extended when the tubular article was molded.
Another broad aspect of the invention provides a mold insert. The mold insert may, but need not, be for molding a tubular article or preform as described above.
The mold insert may comprise a concave cavity portion, which may describe an outer surface of a closed end of a tubular article or preform. The mold insert may comprise a nozzle receiving portion, which may be for engaging an injection nozzle. The mold insert may comprise a passage, e.g. for receipt of a valve stem. The passage may join the concave cavity portion to the nozzle receiving portion.
The concave cavity portion may have a flat base or annular ridge that surrounds and/or joins the concave cavity portion to the passage. The annular ridge may, but need not, have a height that is less than one quarter, or 25%, of a diameter or width of the passage.
Another broad aspect of the invention provides a mold insert, e.g. a tubular article or preform mold insert, the mold insert comprising a concave cavity portion describing an outer surface of a closed end of a tubular article or preform, a nozzle receiving portion for engaging an injection nozzle and a
The tubular article may comprise a witness mark, which may comprise or describe at least part of the flush surface or recess. The flush surface or recess may, but need not, be flat. In some examples, the flush surface or recess may be conical or curved, e.g. spherical. The witness mark may correspond to a surface or portion formed at least in part by a valve stem. The witness mark may comprise a circular indentation or projection. Additionally or alternatively, the witness mark may comprise an annular projection. The witness mark may correspond in part to an outer surface of an end of the valve stem.
The witness mark may correspond at least in part to a passage in a mold insert, e.g. within which the valve stem was received and/or through which the valve stem extended when the tubular article was molded.
Another broad aspect of the invention provides a mold insert. The mold insert may, but need not, be for molding a tubular article or preform as described above.
The mold insert may comprise a concave cavity portion, which may describe an outer surface of a closed end of a tubular article or preform. The mold insert may comprise a nozzle receiving portion, which may be for engaging an injection nozzle. The mold insert may comprise a passage, e.g. for receipt of a valve stem. The passage may join the concave cavity portion to the nozzle receiving portion.
The concave cavity portion may have a flat base or annular ridge that surrounds and/or joins the concave cavity portion to the passage. The annular ridge may, but need not, have a height that is less than one quarter, or 25%, of a diameter or width of the passage.
Another broad aspect of the invention provides a mold insert, e.g. a tubular article or preform mold insert, the mold insert comprising a concave cavity portion describing an outer surface of a closed end of a tubular article or preform, a nozzle receiving portion for engaging an injection nozzle and a
5 Date Recue/Date Received 2023-03-14 passage joining the concave cavity portion to the nozzle receiving portion for receipt of a valve stem, the concave cavity portion comprising a flat base or annular ridge that surrounds and joins the concave cavity portion to the passage, wherein the annular ridge, if present, has a height that is less than one quarter, or 25%, of a diameter or width of the passage.
As used hereinbelow, the term "tubular article" may be replaced with "preform", although the skilled person will appreciate that this invention may be beneficial for other tubular articles, and is therefore not limited to preforms. In addition, the witness mark of the preform may comprise one or more features corresponding substantially to features or dimensions of the passage of the mold insert.
The annular ridge of the mold insert may be for forming part of the recess of the tubular article. The annular ridge of the tubular article may be for forming, or configured to form, in use, the recess of the tubular article with an end of a valve stem received within and/or extending through the passage.
The annular ridge of the mold insert may, but need not, comprise a truncated apex. The truncated apex may describe an annular surface, which may be flat. The annular surface may be for forming, or configured to form, in use, with the end of the valve stem, a base of the recess of the tubular article.
The annular surface may an outer diameter or width, which may be at least 5%
or 10% more than the diameter or width of the passage. Alternatively, the annular surface may be omitted or replaced with an annular edge.
The recess of the tubular article may taper, e.g. from an annular rim surrounding the recess toward a base of the recess. The annular rim of the tubular article may comprise or provide the convex surface surrounding the axial centre or apex. The annular rim may be toroidal.
The annular ridge of the mold insert may taper, e.g. from a base of the concave cavity portion toward the or an apex of the annular ridge. The mold insert may comprise a toroidal recess between the annular ridge and a surrounding portion of the concave cavity portion.
The passage of the mold insert may form an edge with the surrounding concave cavity portion. The edge may describe a right or acute angle, e.g. to provide the flat base or annular ridge. The edge may describe a right or acute angle to provide the truncated apex or annular surface of the annular ridge.
As used hereinbelow, the term "tubular article" may be replaced with "preform", although the skilled person will appreciate that this invention may be beneficial for other tubular articles, and is therefore not limited to preforms. In addition, the witness mark of the preform may comprise one or more features corresponding substantially to features or dimensions of the passage of the mold insert.
The annular ridge of the mold insert may be for forming part of the recess of the tubular article. The annular ridge of the tubular article may be for forming, or configured to form, in use, the recess of the tubular article with an end of a valve stem received within and/or extending through the passage.
The annular ridge of the mold insert may, but need not, comprise a truncated apex. The truncated apex may describe an annular surface, which may be flat. The annular surface may be for forming, or configured to form, in use, with the end of the valve stem, a base of the recess of the tubular article.
The annular surface may an outer diameter or width, which may be at least 5%
or 10% more than the diameter or width of the passage. Alternatively, the annular surface may be omitted or replaced with an annular edge.
The recess of the tubular article may taper, e.g. from an annular rim surrounding the recess toward a base of the recess. The annular rim of the tubular article may comprise or provide the convex surface surrounding the axial centre or apex. The annular rim may be toroidal.
The annular ridge of the mold insert may taper, e.g. from a base of the concave cavity portion toward the or an apex of the annular ridge. The mold insert may comprise a toroidal recess between the annular ridge and a surrounding portion of the concave cavity portion.
The passage of the mold insert may form an edge with the surrounding concave cavity portion. The edge may describe a right or acute angle, e.g. to provide the flat base or annular ridge. The edge may describe a right or acute angle to provide the truncated apex or annular surface of the annular ridge.
6 Date Recue/Date Received 2023-03-14 Another broad aspect of the invention provides a mold insert, e.g. a tubular article or preform mold insert, the mold insert comprising a concave cavity portion describing an outer surface of a closed end of a tubular article or preform, a nozzle receiving portion for engaging an injection nozzle and a passage joining the concave cavity portion to the nozzle receiving portion for receipt of a valve stem, wherein the passage forms an edge with the surrounding concave cavity portion which describes a right or acute angle.
The recess or witness mark of the tubular article may have a diameter or width that is at least 10 times the depth of the recess. Preferably, the recess or witness mark of the tubular article has a diameter or width that is at least 20 times the depth of the recess. For example, the recess or witness mark of the tubular article has a diameter or width that is at least 30 times the depth of the recess, for example at least 35 times the depth of the recess.
In some examples, the passage of the mold insert corresponds substantially to an outer diameter or width of the annular ridge, e.g. an outer diameter of the truncated apex or annular surface of the annular ridge. In such examples, a valve stem received within and/or extending through the passage may be configured to form a base, e.g. the entire base, of the tubular article. The edge formed between the passage and the surrounding concave cavity portion may therefore comprise an acute angle.
The annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert may have a diameter or width, e.g. an outer diameter or width, that is at least 10 times its height.
Preferably, the diameter or width of the annular ridge, truncated apex or annular surface is at least 20 times its height. For example, the diameter or width of the annular ridge, truncated apex or annular surface may be at least 30 times its height, e.g. at least 35 times its height. Additionally or alternatively, the diameter or width of the passage of the mold insert may be at least 10 times, preferably at least 20 times, for example at least 30 or even 35 times, the height of the annular ridge or the truncated apex or annular surface of the annular ridge.
Additionally or alternatively, the annular ridge of the mold insert may have a height that is less than 10% of the diameter or width of the passage, preferably less than 5% of the diameter or width of the passage.
The recess or witness mark of the tubular article may have a diameter or width that is at least 10 times the depth of the recess. Preferably, the recess or witness mark of the tubular article has a diameter or width that is at least 20 times the depth of the recess. For example, the recess or witness mark of the tubular article has a diameter or width that is at least 30 times the depth of the recess, for example at least 35 times the depth of the recess.
In some examples, the passage of the mold insert corresponds substantially to an outer diameter or width of the annular ridge, e.g. an outer diameter of the truncated apex or annular surface of the annular ridge. In such examples, a valve stem received within and/or extending through the passage may be configured to form a base, e.g. the entire base, of the tubular article. The edge formed between the passage and the surrounding concave cavity portion may therefore comprise an acute angle.
The annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert may have a diameter or width, e.g. an outer diameter or width, that is at least 10 times its height.
Preferably, the diameter or width of the annular ridge, truncated apex or annular surface is at least 20 times its height. For example, the diameter or width of the annular ridge, truncated apex or annular surface may be at least 30 times its height, e.g. at least 35 times its height. Additionally or alternatively, the diameter or width of the passage of the mold insert may be at least 10 times, preferably at least 20 times, for example at least 30 or even 35 times, the height of the annular ridge or the truncated apex or annular surface of the annular ridge.
Additionally or alternatively, the annular ridge of the mold insert may have a height that is less than 10% of the diameter or width of the passage, preferably less than 5% of the diameter or width of the passage.
7 Date Recue/Date Received 2023-03-14 The mold insert may be for incorporation within a mold stack.
Another aspect of the invention provides a mold stack, e.g. a tubular article or preform mold stack.
The mold stack may, but need not, be for molding a tubular article or preform as described above. The mold stack may, but need not, comprise a mold insert as described above. The mold insert may comprise or be a cavity insert or a gate insert. The mold stack may comprise a core insert.
The tubular article may comprise an inner surface. The inner surface may comprise a flat or bulged portion. The flat or bulged portion may be aligned with the axial centre of the outer surface. The thickness of the base through the axial centre of the tubular article is preferably within 10% of the radial thickness of the base through the surrounding convex surface of the truncated dome. Preferably, the axial thickness of the base described between any point of the recess and the flat or bulged portion of the inner surface does not vary more than 10%. More preferably, the axial thickness of the base described between any point of the recess and the flat or bulged portion of the inner surface does not vary more than 5%.
The core insert of the mold stack may comprise a flat or recessed end portion.
The flat or recessed end portion may be aligned with the flat base or annular ridge of the aforementioned mold insert, e.g. when the mold stack is in a molding configuration.
The flat or bulged portion of the inner surface of the tubular article may have a larger diameter or width than that of the recess, or of a base or flat base of the recess. The flat or bulged portion of the inner surface of the tubular article may have a diameter or width that is at least 10% larger than that of the recess, or of a base or flat base of the recess.
The flat or recessed end portion of the core insert of the mold stack may have a larger diameter or width than the or an outer diameter or width of the flat base or annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert. The flat or recessed end portion of the core insert of the mold stack may have a diameter or width that is at least 10%
larger than the or an outer diameter or width of the flat base or annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert.
Another aspect of the invention provides a mold stack, e.g. a tubular article or preform mold stack.
The mold stack may, but need not, be for molding a tubular article or preform as described above. The mold stack may, but need not, comprise a mold insert as described above. The mold insert may comprise or be a cavity insert or a gate insert. The mold stack may comprise a core insert.
The tubular article may comprise an inner surface. The inner surface may comprise a flat or bulged portion. The flat or bulged portion may be aligned with the axial centre of the outer surface. The thickness of the base through the axial centre of the tubular article is preferably within 10% of the radial thickness of the base through the surrounding convex surface of the truncated dome. Preferably, the axial thickness of the base described between any point of the recess and the flat or bulged portion of the inner surface does not vary more than 10%. More preferably, the axial thickness of the base described between any point of the recess and the flat or bulged portion of the inner surface does not vary more than 5%.
The core insert of the mold stack may comprise a flat or recessed end portion.
The flat or recessed end portion may be aligned with the flat base or annular ridge of the aforementioned mold insert, e.g. when the mold stack is in a molding configuration.
The flat or bulged portion of the inner surface of the tubular article may have a larger diameter or width than that of the recess, or of a base or flat base of the recess. The flat or bulged portion of the inner surface of the tubular article may have a diameter or width that is at least 10% larger than that of the recess, or of a base or flat base of the recess.
The flat or recessed end portion of the core insert of the mold stack may have a larger diameter or width than the or an outer diameter or width of the flat base or annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert. The flat or recessed end portion of the core insert of the mold stack may have a diameter or width that is at least 10%
larger than the or an outer diameter or width of the flat base or annular ridge, or the truncated apex or annular surface of the annular ridge, of the mold insert.
8 Date Recue/Date Received 2023-03-14 The bulged portion of the tubular article may comprise at least one curved surface, e.g. a convex surface. The convex surface may have a radius of curvature which is at least twice or three times the diameter or width of the recess. In some examples, the convex surface comprises a toroidal surface, in which case the radius of curvature may be in the poloidal direction. In other examples, the convex surface may comprise a spherical surface, in which case the radius of curvature may be at least 20 times, or even 40 or 50 times, the diameter or width of the recess.
The end portion of the core insert of the mold stack may comprise a recess having at least one curved surface, e.g. a concave surface. The concave surface may have a radius of curvature which is at least twice or three times the diameter or width of the passage or an outer diameter or width of the flat base or annular ridge, or truncated apex or annular surface of the annular ridge, of the mold insert. In some examples, the concave surface comprises a toroidal surface, in which case the radius of curvature may be in the poloidal direction. In other examples, the concave surface may comprise a spherical surface, in which case the radius of curvature may be at least 20 times, or even 40 or 50 times the diameter or width of the passage or an outer diameter or width of the flat base or annular ridge, or truncated apex or annular surface of the annular ridge, of the mold insert.
The tubular article may comprise a neck finish, which may be adjacent the open end. The neck finish may comprise securing means or a securing feature, for example a thread or snap fit bead. The neck finish may comprise a radial flange or a support ledge, which may be between the securing means or feature and the closed end.
The mold insert may be or comprise a gate insert. The mold stack may further comprise a cavity insert, which may describe a body of the preform. The mold stack may comprise a split mold insert, which may describe a neck region of the preform.
Another broad aspect of the invention provides a mold, e.g. a tubular article or preform mold. The mold may comprise one or more, e.g. a plurality of, mold inserts or mold stacks as described above.
The mold may comprise a cavity plate, e.g. to which the or each mold insert is mounted. The mold may comprise a core plate, e.g. to which the or each core insert is mounted.
The mold may comprise a stripper plate assembly, e.g. to which the or each split mold insert is movably mounted. The stripper
The end portion of the core insert of the mold stack may comprise a recess having at least one curved surface, e.g. a concave surface. The concave surface may have a radius of curvature which is at least twice or three times the diameter or width of the passage or an outer diameter or width of the flat base or annular ridge, or truncated apex or annular surface of the annular ridge, of the mold insert. In some examples, the concave surface comprises a toroidal surface, in which case the radius of curvature may be in the poloidal direction. In other examples, the concave surface may comprise a spherical surface, in which case the radius of curvature may be at least 20 times, or even 40 or 50 times the diameter or width of the passage or an outer diameter or width of the flat base or annular ridge, or truncated apex or annular surface of the annular ridge, of the mold insert.
The tubular article may comprise a neck finish, which may be adjacent the open end. The neck finish may comprise securing means or a securing feature, for example a thread or snap fit bead. The neck finish may comprise a radial flange or a support ledge, which may be between the securing means or feature and the closed end.
The mold insert may be or comprise a gate insert. The mold stack may further comprise a cavity insert, which may describe a body of the preform. The mold stack may comprise a split mold insert, which may describe a neck region of the preform.
Another broad aspect of the invention provides a mold, e.g. a tubular article or preform mold. The mold may comprise one or more, e.g. a plurality of, mold inserts or mold stacks as described above.
The mold may comprise a cavity plate, e.g. to which the or each mold insert is mounted. The mold may comprise a core plate, e.g. to which the or each core insert is mounted.
The mold may comprise a stripper plate assembly, e.g. to which the or each split mold insert is movably mounted. The stripper
9 Date Recue/Date Received 2023-03-14 plate assembly may be movable, e.g. along the core insert(s), to remove a molded tubular article from the or each 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 or each split mold insert may comprise two or more parts, e.g. halves. Each part may be mounted to a respective one of the slides. The slides may be movable, e.g. as the stripper plate assembly is moved along the core insert(s), to separate the parts of the or each split mold insert, thereby to release a molded tubular article from between the parts.
Another aspect of the invention provides a computer program element comprising and/or describing and/or defining a three-dimensional design, e.g. of the mold, mold stack or mold insert described above or an embodiment thereof. The three-dimensional design may be for use with a simulation means or an additive or subtractive manufacturing means, system or device.
.. The computer program element may be for causing, or operable or configured to cause, an additive or subtractive manufacturing means, system or device to manufacture the mold, mold stack or mold insert described above or an embodiment thereof. The computer program element may comprise computer readable program code means for causing an additive or subtractive manufacturing means, system or device to execute a procedure to manufacture the mold, mold stack or mold insert described .. above or an embodiment thereof.
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 Date Recue/Date Received 2023-03-14 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 cross-sectional view of a preform according to an embodiment of the invention;
lo FIG. 2 depicts an enlarged view of gate area A the preform of FIG.1;
FIG. 3 depicts an enlarged view, similar to that of FIG. 2, but illustrating an alternative configuration of gate area A;
FIG. 4 depicts a cross-sectional view through a mold stack for making the preform of FIG. 1;
FIG. 5 depicts a cross-sectional view of the gate insert of the mold stack of FIG. 4;
FIG. 6 depicts an enlarged view of gate area B of the gate insert of FIG. 5;
FIG. 7 depicts a cross-sectional view of an end portion of the core insert of the mold stack of FIG. 4; and FIG. 8 depicts an enlarged view of the end portion C of the core insert of FIG. 7.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, there is depicted a non-limiting example of a preform 1 according to an embodiment of the invention. The preform 1 is for being blow molded into a container, and includes a central longitudinal axis L, a body portion 10, a base portion 11 describing a closed end 1 1 a and a neck portion 12 describing an open end 12a. The neck portion 12 includes threads 12b adjacent the open end 12a for cooperating with a corresponding screw thread of a closure cap (not shown) in the Date Recue/Date Received 2023-03-14 usual way. The neck portion 12 also includes a radial flange, or support ledge 12c for handling the preform, as is well known in the art.
The base portion 11 has an outer surface 13 formed as a truncated dome with an axial centre, or apex 14, that is recessed relative to a surrounding annular rim 15 of the truncated dome, as shown more clearly in FIG. 2. The overall length of the preform 1 is described from the open end 12a of the neck portion 12 to a peak of the annular rim 15. The annular rim 15 describes a convex surface 15a, which is toroidal in this example, that surrounds and tapers toward a recess 16 having a flat or substantially planar base the centre of which forms the recessed apex 14. In other examples, the recess 16 or surface describing the apex 14 may be conical or curved or spherical, or the apex 14 may be flush with a surrounding, convex surface of the truncated dome, and either surrounded by the annular rim 15 or the annular rim may be omitted, for example if the apex 14 is described by a flat or planar surface that is flush relative to the surrounding convex surface of the truncated dome.
.. The base portion 11 also has an inner concave surface 17, which approximates the outer surface 13, but describes therewith a gradual increase in thickness from the closed end lla to the body portion
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 or each split mold insert may comprise two or more parts, e.g. halves. Each part may be mounted to a respective one of the slides. The slides may be movable, e.g. as the stripper plate assembly is moved along the core insert(s), to separate the parts of the or each split mold insert, thereby to release a molded tubular article from between the parts.
Another aspect of the invention provides a computer program element comprising and/or describing and/or defining a three-dimensional design, e.g. of the mold, mold stack or mold insert described above or an embodiment thereof. The three-dimensional design may be for use with a simulation means or an additive or subtractive manufacturing means, system or device.
.. The computer program element may be for causing, or operable or configured to cause, an additive or subtractive manufacturing means, system or device to manufacture the mold, mold stack or mold insert described above or an embodiment thereof. The computer program element may comprise computer readable program code means for causing an additive or subtractive manufacturing means, system or device to execute a procedure to manufacture the mold, mold stack or mold insert described .. above or an embodiment thereof.
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 Date Recue/Date Received 2023-03-14 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 cross-sectional view of a preform according to an embodiment of the invention;
lo FIG. 2 depicts an enlarged view of gate area A the preform of FIG.1;
FIG. 3 depicts an enlarged view, similar to that of FIG. 2, but illustrating an alternative configuration of gate area A;
FIG. 4 depicts a cross-sectional view through a mold stack for making the preform of FIG. 1;
FIG. 5 depicts a cross-sectional view of the gate insert of the mold stack of FIG. 4;
FIG. 6 depicts an enlarged view of gate area B of the gate insert of FIG. 5;
FIG. 7 depicts a cross-sectional view of an end portion of the core insert of the mold stack of FIG. 4; and FIG. 8 depicts an enlarged view of the end portion C of the core insert of FIG. 7.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, there is depicted a non-limiting example of a preform 1 according to an embodiment of the invention. The preform 1 is for being blow molded into a container, and includes a central longitudinal axis L, a body portion 10, a base portion 11 describing a closed end 1 1 a and a neck portion 12 describing an open end 12a. The neck portion 12 includes threads 12b adjacent the open end 12a for cooperating with a corresponding screw thread of a closure cap (not shown) in the Date Recue/Date Received 2023-03-14 usual way. The neck portion 12 also includes a radial flange, or support ledge 12c for handling the preform, as is well known in the art.
The base portion 11 has an outer surface 13 formed as a truncated dome with an axial centre, or apex 14, that is recessed relative to a surrounding annular rim 15 of the truncated dome, as shown more clearly in FIG. 2. The overall length of the preform 1 is described from the open end 12a of the neck portion 12 to a peak of the annular rim 15. The annular rim 15 describes a convex surface 15a, which is toroidal in this example, that surrounds and tapers toward a recess 16 having a flat or substantially planar base the centre of which forms the recessed apex 14. In other examples, the recess 16 or surface describing the apex 14 may be conical or curved or spherical, or the apex 14 may be flush with a surrounding, convex surface of the truncated dome, and either surrounded by the annular rim 15 or the annular rim may be omitted, for example if the apex 14 is described by a flat or planar surface that is flush relative to the surrounding convex surface of the truncated dome.
.. The base portion 11 also has an inner concave surface 17, which approximates the outer surface 13, but describes therewith a gradual increase in thickness from the closed end lla to the body portion
10. The inner surface 17 includes a bulge 18 with an axial centre or apex 19, opposite the recessed apex 14. A first thickness Ti is described between the outer apex 14 and the inner apex 19, and a second thickness T2 is described between the peak of the rim 15 and the base of the bulge 18. The first thickness Ti is preferably the same or less than the second thickness T2, but this is not critical.
In this example, the bulge 18 is toroidal and is formed with a radius R in the poloidal direction that results in the inner apex 19 being recessed slightly. However, the bulge 18' may be spheroidal, with a much larger radius R', as shown in FIG. 3. This can vary the relationship between the first and second thicknesses Ti', T2', but it is still preferable that the first thickness Ti' is less than, or substantially the same as, the second thickness T2'.
The flat base of the recess 16 has a depth D and a diameter, or width Wi delineated by the rim 15. The bulge 18 also has a diameter, or width W2, which is larger than the diameter or width Wi of the base of the recess 16. In this example, the diameter or width W2 of the bulge 18 corresponds substantially with the diameter of the peak of the annular rim 15. The recess 16 is shallow, in this case having a depth D that is approximately 2.5% of its diameter or width Wi. It has been determined that this relationship can vary, but increasing the relative depth D of the recess 16, for example in order to Date Recue/Date Received 2023-03-14 provide a more effective delineation between the gate region and the surrounding material to be heated and stretched, can create other issues.
More particularly, the skilled person will appreciate that reducing the first and second thicknesses Ti, Tz, Ti', Tz' excessively could be detrimental to the ability of the base 11 of the preform 1 to withstand the force applied by the stretch rod (not shown), during the blow molding process. An increase in the depth D would therefore necessitate a corresponding increase in the height of the bulge 18, to maintain the requisite thickness. If such an increase is substantial, the skilled person will appreciate that this will increase the volume, and therefore the weight, of material required to make the preform 1.
It has been determined that an increase in depth D of the recess to a value over 10% that of the its diameter or width W can be particularly detrimental. As such, recess 16 should have a diameter or width Wi that is at least 10 times its depth D, preferably at least 20 times its depth D and more preferably at least 30 times its depth D.
Whilst it is possible to reduce the depth D of the recess to zero, thereby providing a flat base in place of the recess 16, this is less preferable as it can reduce substantially the effectiveness of the aforementioned delineation between the gate region and the surrounding material to be heated and stretched.
Turning now to Figure 4, there is shown a mold stack MS for molding the preform 1 of Figures 1 and 2. The mold stack MS includes a core assembly 2, a split mold insert 3, a cavity insert 4 and a gate insert 5. It is, however, envisaged that the cavity insert 4 and gate insert 5 may be provided as a single mold insert.
The core assembly 2 includes a core insert 20, a core ring 21 surrounding an intermediate part of the core insert 20 and a lock ring 22 surrounding the core insert 20 and core ring 21 for securing the core assembly 2 to a core plate (not shown). The core ring 21 is mounted on a step of the core insert 20 and has a male taper 21a that cooperates with a female taper 22a of the lock ring 22 in a manner that is known in the art and will not be described further herein. The lock ring 22 also has a further female taper 22b on its split-mold facing side. The core insert 20 has a molding surface 23 describing an inner surface of the preform 1. The molding surface 23 includes a base molding portion 24 for molding the inner surface of the base portion 11 of the preform 1.
Date Recue/Date Received 2023-03-14 The split mold insert 3 includes two parts 30, 31 each describing half of the outer surface of the neck portion 12 of the preform 1, and the cavity insert 4 describes the outer surface of the body portion 10 of the preform 1, in the usual way. The split mold insert 3 in this example includes a male taper 32, 33 on each of its core-facing and cavity-facing sides. The male taper 32 on the core-facing side of the split mold insert 3 cooperates with the further female taper 22b of the lock ring 22. The male taper 33 on the cavity-facing side of the split mold insert 3 cooperates with a female taper 40 at a first end of the cavity insert 4.
The gate insert 5 abuts a second end of the cavity insert 4, and includes a concave cavity portion 50 with a molding surface 51 describing the outer surface of the base portion 11 of the preform 1. As illustrated more clearly in FIG. 5, the gate insert 5 also includes a nozzle receiving portion 52 for engaging an injection nozzle (not shown) and a passage 53 joining the concave cavity portion 50 to the nozzle receiving portion 52.
A gate area B, including the passage 53 and adjacent portions of each of the concave cavity portion 50 and the nozzle receiving portion 52, is illustrated more clearly in FIG. 6.
The concave cavity portion 50 in this example includes an annular ridge 54 with a truncated, flat peak 55 that surrounds and joins the concave cavity portion 50 to the passage 53. The annular ridge 54 is joined to the concave cavity portion 50 by a curved transition, which defines an inflection in the direction of the adjoining region of the concave cavity portion 50 to form a toroidal molding surface 51a corresponding to the convex surface 15a of the annular rim 15. As a result, the annular ridge 54 tapers from the concave cavity portion 50 toward its truncated, flat peak 55.
The annular ridge 54 has a height H and a diameter or width W3 that correspond, respectively, to the depth D and diameter or width Wi of the flat base of the recess 16 of the preform 1 of Figure 1. As explained in relation to the preform 1, the depth D and diameter or width Wi of the recess 16, and therefore the height H and diameter or width W3 of the annular ridge 54, may vary within the aforementioned ranges.
In this example, the truncated, flat peak 55 of the annular ridge 54 forms a right angle edge 56 with the passage 53. The outer diameter or width W3 of the flat peak 55 in this case is approximately 15%
larger than a diameter or width W4 of the passage 53. The passage 53 is sized for slidably receiving a Date Recue/Date Received 2023-03-14 valve stem (not shown) of an injection nozzle (not shown) with minimal clearance such that, in its deployed position, the flat end of the valve stem (not shown) is aligned with the surrounding flat peak 55 of the annular ridge 54, thereby to describe therewith a substantially planar recess 16.
The skilled person will appreciate that the recess 16 may include a shallow witness mark, for example from a small gap between the end of the valve stem (not shown) and the surrounding end portion of the passage 53, but this would be minimal and, if present, this witness mark is expected to be recessed with respect to the surrounding rim 15. Thus, the forementioned gate nub present in typical preforms is effectively eliminated, together with its funnel shaped transition to the preform base. The skilled person will appreciate that this reduces the weight of the base portion 11 of the preform 1, and is believed to improve material distribution for the reasons given above.
It is envisaged that this width may be reduced, even to the point of omitting the flat peak 55 altogether, resulting in an acute or sharp edge between the outer, curved and tapering side of the annular ridge 54 and the passage 53. In such cases, the end of the valve stem (not shown) alone would describe the recess 16. Whilst this may be advantageous, for example because the edges of any resulting witness mark would be aligned with the outer edge of the recess, the resulting sharp edge of the gate insert 5 between the outer side of the annular ridge 54 and the passage 53 is undesirable for reasons that would be appreciated by those skilled in the art. To mitigate this, the outer diameter or width W3 of the flat peak 55 is preferably, although not necessarily, at least 5% larger than a diameter or width W4 of the passage 53.
Turning now to FIG. 7, the core insert 20 includes an end portion C, shown more clearly in FIG. 8, that is truncated. More specifically, the base molding portion 24 of the molding surface 23 is in the form of a truncated dome, in which its end is truncated by a distance T. In this example, the truncated outer surface 13 of the base portion 11 of the preform 1 is also truncated by a similar distance. The diameter or width Ws of truncated end corresponds to the diameter or width W2 of the bulge 18 of the closed end lla of the preform 1, and is therefore larger than the outer diameter or width W3 of the flat peak 55 of the annular ridge 54 of the gate insert 5.
A shallow, toroidal recess 25 describes or delineates the truncated end in this case. The recess 25 has a poloidal radius R, configured to ensure that the axial thicknesses Ti, T2 of the end of the preform base 11 are substantially the same. This configuration corresponds to the closed end 1 1 a of FIG. 2.
Date Recue/Date Received 2023-03-14 The skilled person will appreciate that a similar core insert 20 to that shown in FIGs 7 and 8 could be used to make the closed end 11 a' of FIG. 3, but in such a case the toroidal recess 25 would be replaced with a spherical recess for making the spherical bulge 18' of the closed end
In this example, the bulge 18 is toroidal and is formed with a radius R in the poloidal direction that results in the inner apex 19 being recessed slightly. However, the bulge 18' may be spheroidal, with a much larger radius R', as shown in FIG. 3. This can vary the relationship between the first and second thicknesses Ti', T2', but it is still preferable that the first thickness Ti' is less than, or substantially the same as, the second thickness T2'.
The flat base of the recess 16 has a depth D and a diameter, or width Wi delineated by the rim 15. The bulge 18 also has a diameter, or width W2, which is larger than the diameter or width Wi of the base of the recess 16. In this example, the diameter or width W2 of the bulge 18 corresponds substantially with the diameter of the peak of the annular rim 15. The recess 16 is shallow, in this case having a depth D that is approximately 2.5% of its diameter or width Wi. It has been determined that this relationship can vary, but increasing the relative depth D of the recess 16, for example in order to Date Recue/Date Received 2023-03-14 provide a more effective delineation between the gate region and the surrounding material to be heated and stretched, can create other issues.
More particularly, the skilled person will appreciate that reducing the first and second thicknesses Ti, Tz, Ti', Tz' excessively could be detrimental to the ability of the base 11 of the preform 1 to withstand the force applied by the stretch rod (not shown), during the blow molding process. An increase in the depth D would therefore necessitate a corresponding increase in the height of the bulge 18, to maintain the requisite thickness. If such an increase is substantial, the skilled person will appreciate that this will increase the volume, and therefore the weight, of material required to make the preform 1.
It has been determined that an increase in depth D of the recess to a value over 10% that of the its diameter or width W can be particularly detrimental. As such, recess 16 should have a diameter or width Wi that is at least 10 times its depth D, preferably at least 20 times its depth D and more preferably at least 30 times its depth D.
Whilst it is possible to reduce the depth D of the recess to zero, thereby providing a flat base in place of the recess 16, this is less preferable as it can reduce substantially the effectiveness of the aforementioned delineation between the gate region and the surrounding material to be heated and stretched.
Turning now to Figure 4, there is shown a mold stack MS for molding the preform 1 of Figures 1 and 2. The mold stack MS includes a core assembly 2, a split mold insert 3, a cavity insert 4 and a gate insert 5. It is, however, envisaged that the cavity insert 4 and gate insert 5 may be provided as a single mold insert.
The core assembly 2 includes a core insert 20, a core ring 21 surrounding an intermediate part of the core insert 20 and a lock ring 22 surrounding the core insert 20 and core ring 21 for securing the core assembly 2 to a core plate (not shown). The core ring 21 is mounted on a step of the core insert 20 and has a male taper 21a that cooperates with a female taper 22a of the lock ring 22 in a manner that is known in the art and will not be described further herein. The lock ring 22 also has a further female taper 22b on its split-mold facing side. The core insert 20 has a molding surface 23 describing an inner surface of the preform 1. The molding surface 23 includes a base molding portion 24 for molding the inner surface of the base portion 11 of the preform 1.
Date Recue/Date Received 2023-03-14 The split mold insert 3 includes two parts 30, 31 each describing half of the outer surface of the neck portion 12 of the preform 1, and the cavity insert 4 describes the outer surface of the body portion 10 of the preform 1, in the usual way. The split mold insert 3 in this example includes a male taper 32, 33 on each of its core-facing and cavity-facing sides. The male taper 32 on the core-facing side of the split mold insert 3 cooperates with the further female taper 22b of the lock ring 22. The male taper 33 on the cavity-facing side of the split mold insert 3 cooperates with a female taper 40 at a first end of the cavity insert 4.
The gate insert 5 abuts a second end of the cavity insert 4, and includes a concave cavity portion 50 with a molding surface 51 describing the outer surface of the base portion 11 of the preform 1. As illustrated more clearly in FIG. 5, the gate insert 5 also includes a nozzle receiving portion 52 for engaging an injection nozzle (not shown) and a passage 53 joining the concave cavity portion 50 to the nozzle receiving portion 52.
A gate area B, including the passage 53 and adjacent portions of each of the concave cavity portion 50 and the nozzle receiving portion 52, is illustrated more clearly in FIG. 6.
The concave cavity portion 50 in this example includes an annular ridge 54 with a truncated, flat peak 55 that surrounds and joins the concave cavity portion 50 to the passage 53. The annular ridge 54 is joined to the concave cavity portion 50 by a curved transition, which defines an inflection in the direction of the adjoining region of the concave cavity portion 50 to form a toroidal molding surface 51a corresponding to the convex surface 15a of the annular rim 15. As a result, the annular ridge 54 tapers from the concave cavity portion 50 toward its truncated, flat peak 55.
The annular ridge 54 has a height H and a diameter or width W3 that correspond, respectively, to the depth D and diameter or width Wi of the flat base of the recess 16 of the preform 1 of Figure 1. As explained in relation to the preform 1, the depth D and diameter or width Wi of the recess 16, and therefore the height H and diameter or width W3 of the annular ridge 54, may vary within the aforementioned ranges.
In this example, the truncated, flat peak 55 of the annular ridge 54 forms a right angle edge 56 with the passage 53. The outer diameter or width W3 of the flat peak 55 in this case is approximately 15%
larger than a diameter or width W4 of the passage 53. The passage 53 is sized for slidably receiving a Date Recue/Date Received 2023-03-14 valve stem (not shown) of an injection nozzle (not shown) with minimal clearance such that, in its deployed position, the flat end of the valve stem (not shown) is aligned with the surrounding flat peak 55 of the annular ridge 54, thereby to describe therewith a substantially planar recess 16.
The skilled person will appreciate that the recess 16 may include a shallow witness mark, for example from a small gap between the end of the valve stem (not shown) and the surrounding end portion of the passage 53, but this would be minimal and, if present, this witness mark is expected to be recessed with respect to the surrounding rim 15. Thus, the forementioned gate nub present in typical preforms is effectively eliminated, together with its funnel shaped transition to the preform base. The skilled person will appreciate that this reduces the weight of the base portion 11 of the preform 1, and is believed to improve material distribution for the reasons given above.
It is envisaged that this width may be reduced, even to the point of omitting the flat peak 55 altogether, resulting in an acute or sharp edge between the outer, curved and tapering side of the annular ridge 54 and the passage 53. In such cases, the end of the valve stem (not shown) alone would describe the recess 16. Whilst this may be advantageous, for example because the edges of any resulting witness mark would be aligned with the outer edge of the recess, the resulting sharp edge of the gate insert 5 between the outer side of the annular ridge 54 and the passage 53 is undesirable for reasons that would be appreciated by those skilled in the art. To mitigate this, the outer diameter or width W3 of the flat peak 55 is preferably, although not necessarily, at least 5% larger than a diameter or width W4 of the passage 53.
Turning now to FIG. 7, the core insert 20 includes an end portion C, shown more clearly in FIG. 8, that is truncated. More specifically, the base molding portion 24 of the molding surface 23 is in the form of a truncated dome, in which its end is truncated by a distance T. In this example, the truncated outer surface 13 of the base portion 11 of the preform 1 is also truncated by a similar distance. The diameter or width Ws of truncated end corresponds to the diameter or width W2 of the bulge 18 of the closed end lla of the preform 1, and is therefore larger than the outer diameter or width W3 of the flat peak 55 of the annular ridge 54 of the gate insert 5.
A shallow, toroidal recess 25 describes or delineates the truncated end in this case. The recess 25 has a poloidal radius R, configured to ensure that the axial thicknesses Ti, T2 of the end of the preform base 11 are substantially the same. This configuration corresponds to the closed end 1 1 a of FIG. 2.
Date Recue/Date Received 2023-03-14 The skilled person will appreciate that a similar core insert 20 to that shown in FIGs 7 and 8 could be used to make the closed end 11 a' of FIG. 3, but in such a case the toroidal recess 25 would be replaced with a spherical recess for making the spherical bulge 18' of the closed end
11 a'.
It will be appreciated that the configuration of the preform 1, particularly of the closed end 11a, 11 a' thereof, may vary, particularly although not exclusively as described above.
Similarly, the mold stack MS or molding surface described by the mold stack MS, particularly by the core insert 20 and/or the gate insert 5, may also 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.
Date Regue/Date Received 2023-03-14
It will be appreciated that the configuration of the preform 1, particularly of the closed end 11a, 11 a' thereof, may vary, particularly although not exclusively as described above.
Similarly, the mold stack MS or molding surface described by the mold stack MS, particularly by the core insert 20 and/or the gate insert 5, may also 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.
Date Regue/Date Received 2023-03-14
Claims (30)
1. A preform mold insert comprising a concave cavity portion describing an outer surface of a closed end of a preform, a nozzle receiving portion for engaging an injection nozzle and a passage joining the concave cavity portion to the nozzle receiving portion, the concave cavity portion comprising a flat base or annular ridge that surrounds and joins the concave cavity portion to the passage, wherein the annular ridge, if present, has a height that is less than one quarter of a diameter of the passage.
2. The preform mold insert of claim 1, wherein the annular ridge comprises a truncated apex describing a flat annular surface having an outer diameter that is at least 5%
more than the diameter of the passage.
more than the diameter of the passage.
3. The preform mold insert of claim 1 or claim 2, wherein the annular ridge tapers from a base of the concave cavity portion toward the or an apex of the annular ridge.
4. The preform mold insert of claim 3 comprising a toroidal recess between the annular ridge and a surrounding portion of the concave cavity portion.
5. The preform mold insert of any preceding claim, wherein the passage forms an edge with the surrounding concave cavity portion which describes a right or acute angle to provide the flat base or annular ridge.
6. The preform mold insert of any preceding claim, wherein the annular ridge has a height that is less than 10% of the diameter of the passage.
7. The preform mold insert of any preceding claim, wherein the annular ridge has a height that is less than 5% of the diameter of the passage.
8. The preform mold insert according to any preceding claim, wherein the preform mold insert is a gate insert.
Date Recue/Date Received 2023-03-14
Date Recue/Date Received 2023-03-14
9. A prefomi mold stack comprising a core insert and the prefomi mold insert according to any preceding claim, wherein the core insert comprises a flat or recessed end portion aligned with the flat base or annular ridge of the prefomi mold insert when the mold stack is in a molding configuration.
10. The preform mold stack of claim 9, wherein the flat or recessed end portion of the core insert has a larger diameter than the or an outer diameter of the flat base or of a truncated apex of the annular ridge of the preform mold insert.
11. The preform mold stack of claim 9 or claim 10, wherein the end portion comprises a recess comprising at least one curved surface.
12. The preform mold stack of claim 11, wherein the recessed end portion comprises a concave surface.
13. The preform mold stack of claim 12, wherein the concave surface has a radius of curvature which is at least twice the diameter of the passage.
14. The preform mold stack of claim 13, wherein the concave surface comprises a toroidal surface and the radius of curvature is in the poloidal direction.
15. The preform mold stack of claim 13, wherein the concave surface comprises a spherical surface and the radius of curvature is at least 20 times the diameter of the passage.
16. The preform mold stack of any one of claims 9 to 15, wherein the preform mold insert is a gate insert and the preform mold stack further comprises a cavity insert describing a body of the preform and a split mold insert describing a neck region of the prefomi.
17. A prefomi mold comprising a plurality of mold stacks according to any one of claims 9 to 16.
18. A prefomi for being blow molded into a container, the prefomi comprising a closed end having an outer surface formed by a truncated dome with an axial centre, or apex, that is flush or Date Recue/Date Received 2023-03-14 recessed relative to a surrounding convex surface of the truncated dome, wherein the recess, if present, has a diameter that is at least 10 times its depth.
19. The preform of claim 18, wherein the recess tapers from an annular rim surrounding the recess toward a base of the recess.
20. The preform of claim 19, wherein the annular rim is toroidal.
21. The preform of any one of claims 18 to 20, wherein the recess has a diameter that is at least 20 times its depth.
22. The preform of any one of claims 18 to 21 comprising an inner surface with a flat or bulged portion aligned with the axial centre of the outer surface.
23. The preform of claim 22, wherein the flat or bulged portion of the inner surface has a larger diameter than that of a flat base of the recess.
24. The preform of claim 22 or claim 23, wherein the bulged portion comprises at least one curved surface.
25. The preform of claim 24, wherein the bulged portion comprises a convex surface.
26. The preform of claim 25, wherein the convex surface has a radius of curvature which is at least twice the diameter of the recess.
27. The preform of claim 26, wherein the convex surface comprises a toroidal surface and the radius of curvature is in the poloidal direction.
28. The preform of claim 27, wherein the convex surface comprises a spherical surface and the radius of curvature is at least 20 times the diameter of the recess.
29. The preform of any one of claims 18 to 28 comprising a neck finish adjacent the open end, wherein the neck finish comprises securing means, for example a thread or snap fit bead.
Date Recue/Date Received 2023-03-14
Date Recue/Date Received 2023-03-14
30. The prefomi of claim 29, wherein the neck finish comprises a support ledge between the securing means and the closed end.
Date Recue/Date Received 2023-03-14
Date Recue/Date Received 2023-03-14
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US202363481812P | 2023-01-27 | 2023-01-27 | |
| US63/481,812 | 2023-01-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA3192997A1 true CA3192997A1 (en) | 2023-05-12 |
Family
ID=86282205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA3192997A Pending CA3192997A1 (en) | 2023-01-27 | 2023-03-14 | Molds, mold assemblies, stack components and molded articles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA3192997A1 (en) |
-
2023
- 2023-03-14 CA CA3192997A patent/CA3192997A1/en active Pending
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