Patent Application
20100326947
The present invention generally relates to, but is not limited to, a molding systems and processes, and more specifically the present invention relates to, but is not limited to, a preform and a mold stack for producing the preform.
Molding is a process by virtue of which a molded article can be formed from molding material by using a molding system. Various molded articles can be formed by using the molding process, such as an injection molding process. One example of a molded article that can be formed, for example, from polyethylene terephthalate (PET) material is a preform that is capable of being subsequently blow-molded into a beverage container, such as, a bottle and the like.
As an illustration, injection molding of PET material involves heating the PET material (ex. PET pellets, PEN powder, PLA, etc.) to a homogeneous molten state and injecting, under pressure, the so-melted PET material into a molding cavity defined, at least in part, by a female cavity piece and a male core piece mounted respectively on a cavity plate and 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 female cavity and the male core pieces together against the pressure of the injected PET 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 PET material is then cooled to a temperature sufficient to enable ejection of the so-formed molded article from the mold. 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 male core piece. Thereafter, the molded article can be ejected off the male core piece by use of a suitable ejection structure. Numerous ejection structures are known to assist in removing the molded articles from the male core piece. Examples of the ejection structures include stripper plates, stripper rings and neck rings, ejector pins, etc.
With reference to
The preform 100 has a number of additional structural features that fulfill one or more functions. For example, within the neck portion 102, there is provided a thread 108. The purpose of the thread 108 is to cooperate with a complementary thread of a closure device (not depicted) to maintain a substance (such as a beverage and the like) contained within a final-shaped container produced from the preform 100 (when such a final-shaped container is blow-molded and eventually filled with the substance). The neck portion 102 further includes a tamper-evident band 110. The purpose of the tamper-evident band 110 is to cooperate with a complementary tamper-evident structure of the closure device (not depicted) to provide a visual indication of when a seal between the final-shaped container produced from the preform 100 and the closure device (not depicted) has been compromised (or, simply put, when the closure device and the final-shaped container produced from the preform 100 have been at least partially opened).
Furthermore, the neck portion 102 comprises a support ledge 112. The support ledge 112 performs multiple functions including, but not limited to, cooperating with various handling devices and structures during injection molding and blow molding stages of production of the preform 100 (for example, cooperation with ejection structures and/or handling structures) and the final-shaped container from the preform 100 (for example, cooperation with the blow-molding equipment to provide sealing and/or handling structures, etc.). A typical implementation of the support ledge 112 comprises a generally annular protrusion. Generally speaking, the support ledge 112 has an external ring 112a and an internal ring 112b with an annulus of molding material 112c defined therebetween.
Another example of how the support ledge 112 can be implemented is depicted in
With continued reference to
Within the description presented herein above, the term “portion” means substantially half of the respective part (ex. the thread 108, the tamper-evident band 110 and the support ledge 112) defined by one of the first split mold insert 304 and the second split mold insert 304.
It is worthwhile noting that the first sub-portion 314 of each of the first split mold insert 304 and the second split mold insert 306 comprises a generally half-circular groove.
An example of the pair of split mold inserts 302 is disclosed in a co-owned US patent application bearing a publication number 2006/0283210 published on Dec. 21, 2006 to Dubuis et al and which discloses, inter alia, a mold split insert for use in a molding stack assembly, and in particular a preform mold neck ring insert for use in an injection molding stack assembly for making bottle mold preforms. The split insert comprises a body with a molding surface configured thereon. The split insert also includes a coolant channel configured in the body with a partition arranged therein. The partition dividing a portion of the coolant channel into a first and a second branch. A transfer coolant channel is configured between the branches.
According to a first broad aspect of the present invention, there is provided a preform suitable for blow-molding into a final-shaped container. The preform comprises a neck portion; a gate portion; and a body portion extending between said neck portion and said gate portion; the neck portion including a support ledge, the support ledge being associated with a metal contacting surface and a weight, and wherein a ratio of the metal contacting surface to the weight modulated for a base line support ledge thickness curve is selected in a range of between 0.1 and 1000.
According to a second broad aspect of the present invention, there is provided a split mold insert for defining at least a neck portion of a preform. The split mold insert comprises a body having a molding surface defining portion that includes a first sub-portion for defining, in use, a portion of a support ledge of the neck portion, the support ledge being associated with a metal contacting surface, a weight and a thickness; the first sub-portion being associated with a generally scalloped geometry so selected as to define the support ledge to be associated with a ratio of the metal contacting surface to the weight modulated for a base line support ledge thickness curve is selected in a range of between 0.1 and 1000.
According to a third broad aspect of the present invention, there is provided a preform suitable for blow-molding into a final-shaped container. The preform comprises a neck portion; a gate portion; and a body portion extending between said neck portion and said gate portion; the neck portion including a support ledge having a crenated edge, the support ledge being associated with a metal contacting surface being contributed to partially by the crenated edge and a weight, and wherein a ratio of the metal contacting surface to the weight modulated for base line support ledge thickness curve is selected in a range of between 0.1 and 1000
According to a fourth broad aspect of the present invention, there is provided a preform suitable for blow-molding into a final-shaped container. The preform comprises a neck portion; a gate portion; and a body portion extending between said neck portion and said gate portion; the neck portion including a support ledge, the support ledge being associated with a metal contacting surface and a weight, and wherein a ratio of the metal contacting surface to the weight is at least 1004 mm2/g.
According to yet another broad aspect of the present invention, there is provided a split mold insert for defining at least a neck portion of a preform. The split mold insert comprises a body having a molding surface defining portion that includes a first sub-portion for defining, in use, a portion of a support ledge of the neck portion, the support ledge being associated with a metal contacting surface, a weight and a thickness; the first sub-portion being associated with a generally scalloped geometry so selected as to define the support ledge to be associated with a ratio of the metal contacting surface is at least 1004 mm2/g.
These and other aspects and features of non-limiting embodiments of the present invention will now become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the invention in conjunction with the accompanying drawings.
A better understanding of the non-limiting embodiments of the present invention (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the non-limiting embodiments along with the following drawings, in which:
The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.
With reference to
The pair of split mold inserts 402 comprises a first split mold insert 404 and a second split mold insert 406. Description to be presented herein below will mainly use the first split mold insert 404 as an example, but same teachings equally apply to the second split mold insert 406.
The pair of split mold inserts 402 is configured for defining a portion of a preform 500 (depicted in
The neck portion 502 comprises a thread 508, which can be implemented in substantially the same manner as the thread 108 described herein above. The neck portion 502 further includes a tamper-evident band 510, which can be implemented in substantially the same manner as the tamper-evident band 110 described herein above. It should be noted that in alternative non-limiting embodiments of the present invention, the thread 508 and the tamper-evident band 510 can be implemented differently. For example, there are numerous known designs and implementations for the thread 108. Some of the known designs and implementations include, but are not limited to, ALCOA 1716, ALCOA 1788, BPF-C, PCO-1810, PCO-1815, PCF-43P-1, ALCOA 1690, PCO 1816 and the like.
The neck portion 502 further comprises a support ledge 512 implemented according to a non-limiting embodiment of the present invention.
Returning to the description of
The body 408 further comprises a molding surface defining portion 414 for defining at least a portion of the neck portion 502 of the preform 500 (
With continued reference to
Before it is described how the exact configuration for the generally scalloped geometry 422 is selected, quick reference is made once again to
The support ledge 512 is also associated with a split line 580 which is defined where the first split mold insert 404 meets the second split mold insert 406. The split line 580 can be said to divide the support ledge 512 (and the neck portion 502, generally) into two virtual halves (not separately numbered), that are substantially mirror images of each other. Put another way, the support ledge 512 is divided by the split line 580 into a first virtual half (not separately numbered) and a second virtual half (not separately numbered). Within the embodiment depicted in
It is further worthwhile noting that the support ledge 512 can be said to be associated with a metal contacting surface 520. Generally speaking, the metal contacting surface 520 is a surface of the support ledge 512 that is in contact, during use, with the molding surface defining portion 414 and, more specifically, mainly with the first sub-portion 420. It is worthwhile noting that a portion of the metal contacting surface 520 is contributed to by the crenated edge 514. The support ledge 512 is also associated with a weight, which is the weight of molding material used for defining the support ledge 512. The support ledge 512 is also associated with a thickness, which is a distance between an upper extreme and a lower extreme thereof.
Within embodiments of the present invention, it can be said that the support ledge 512 is associated with a contact surface to weight ratio (CSTWR). Within embodiments of the present invention, the contact surface to weight ratio (CSTWR) can be calculated using the following formulae:
where,
CSTWR is the contact surface to weight ratio;
MCS is the metal contacting surface 520 of the support ledge 512;
W is the weight of the support ledge 512.
In a given example of an implementation (which uses the standard PCO neck finish and a thickness of the support ledge 512 of 1.45 mm), the contact surface to weight ratio (CSTWR) ranges between 1004 mm2/g and 1062.1 mm2/g. Within this embodiment of the present invention, the contact surface to weight ratio (CSTWR) varied depending on a thickness of the support ledge 512 and a particular design of the crenated edge 514 (for example, the number of the plurality of protrusions 516 and the plurality of depressions 518 used). As means of comparison, the contact surface to weight ratio (CSTWR) for the preform 100 of
Accordingly, it can be said that within certain non-limiting embodiments of the present invention, the contact surface to weight ratio (CSTWR) is selected from at least 1004 mm2/g.
It should be noted that in alternative non-limiting embodiments of the present invention, the contact surface to weight ratio (CSTWR) can be selected in a different range, which will depend on different parameters, such as for example, particular design of the crenated edge 514 (for example, the number of the plurality of protrusions 516 and the plurality of depressions 518 used), thickness of the support ledge, overall neck finish design and the like. Generally speaking, as the thickness of the support ledge 512 (or the support ledge 112 or the support ledge 212) increases, the contact surface to weight ratio (CSTWR) decreases. However, it has been found that the contact surface to weight ratio (CSTWR) for the preform 500 is generally higher than the same ratio for the preform 100 or the preform 200 (provided that thickness and design of the neck finish remain the same).
It can be further said that within embodiments of the present invention, the support ledge 512 is associated with a contact surface to weight ratio modulated for a base line support ledge thickness curve (CSTWRM), which can be calculated using the following formulae:
where,
CSTWRM is the contact surface to weight ratio modulated for a base line support ledge thickness curve;
MCS is the metal contacting surface 520 of the support ledge 512;
W is the weight of the support ledge 512; and
F (T) is a function of a contact surface to weight ratio over a selected range of thickness associated with a selected base line support ledge.
The function of the contact surface to weight ratio over the selected range of thickness of the base line support ledge (F(T)) can be calculated using the following formulae:
F(T)=ACONSTANT×T2−BCONSTANT×T+CCONSTANT
Within embodiments of the present invention, values for ACONSTANT, BCONSTANT and CCONSTANT are generated using a function of a curve representative of the contact surface to weight ratio over a selected range of thickness of the selected base line support ledge. In a particular non-limiting example of the present invention, the function F(T) is calculated using the following values for constants ACONSTANT, BCONSTANT and CCONSTANT:
F(T)=37.439×T2−411.08×T+1510.5
Within this specific example, the values for ACONSTANT, BCONSTANT and CCONSTANT have been generated using values associated with the preform 200 of
In various embodiments of the present invention, the contact surface to weight ratio modulated for a base line support ledge thickness curve (CSTWRM) ranges between 0.1 and 1000.
In a particular non-limiting example of an implementation of the support ledge 512, the metal contacting surface 520 (MCS) of the support ledge 512 is 718.2 mm2 and the weight (W) of the support ledge 512 is 0.702 grams and the thickness of the support ledge 512 is 1.45 mm. It should be noted that the metal contacting surface 520 and the weight is contributed to, in substantially equal parts, by the first and second virtual halves (not separately numbered) of the support ledge 512. Within this non-limiting embodiment of the present invention, the contact surface to weight ratio (CSTWR) is 1034.6 mm2/g. Furthermore, the contact surface to weight ratio modulated for a base line support ledge thickness curve (CSTWRM) using the preform 200 of
In another particular non-limiting example of an implementation of the support ledge 512, the metal contacting surface 520 (MCS) of the support ledge 512 is 718.2 mm2 and the weight (W) of the support ledge 512 is 0.702 grams and the thickness of the support ledge 512 is 1.45 mm. It should be noted that the metal contacting surface 520 and the weight is contributed to, in substantially equal parts, by the first and second virtual halves (not separately numbered) of the support ledge 512. Within this non-limiting embodiment of the present invention, the contact surface to weight ratio (CSTWR) is 1023.6 mm2/g. Furthermore, the contact surface to weight ratio modulated for a base line support ledge thickness curve (CSTWRM) using the preform 200 of
It should be noted, however, that illustration of
Even more specifically,
When designing the generally scalloped geometry 422, the following demolding considerations can be additionally taken into consideration.
Generally speaking, in those embodiments where an even number of protrusions (for example, the protrusion 616b) is selected, the implementation is considered to be generally standard where a split line (not depicted) passes through a first one and a second one of diametrically opposed ones of a plurality of protrusions (such the four instances of the protrusion 616b). Within these embodiments of the present invention, the generally scalloped geometry 422 is further selected such that the split line 580 is defined substantially through a center of a first one and a second one of diametrically opposed ones of the plurality of protrusions 516.
Alternatively, in some embodiments of the present invention, the geometry of a given one of the plurality of protrusions 516 that is traversed by the split line 580 can be modified to prevent creation of a negative angle that would be otherwise detrimental to demolding. Generally speaking, in those embodiments of the present invention where an odd number of protrusions (for example, the five instances of the protrusion 616c) is selected, modification to some of the protrusions (for example, some of the five instances of the protrusion 616c) and/or some of the depressions (for example, some of the five instances of the depression 618c) is required. Within these embodiments of the present invention, the implementation is considered to be generally “modified”, where a split line (not depicted) passes through one of a plurality of protrusions (for example, the five instances of the protrusion 616c) and a modified depression (such as the modified one of the five instances of the depression 618c) in a modified area (such as, the area 680c).
Furthermore, is some embodiments of the present invention, the implementation can be considered generally undiversified, such as the case, for example, with the support ledge 612b, where all of the plurality of protrusions (such as, for example, all of the four instances of the protrusion 616b) are implemented in substantially the same manner. Put another way, within these embodiments of the present invention, a given one of the plurality of protrusions (such as, for example, one of the four instances of the protrusion 616b) is implemented in a substantially the same manner as another one of the plurality of protrusions (such as, for example, another one of the four instances of the protrusion 616b).
In other embodiments of the present invention, the implementation can be considered generally diversified, such as the case, for example, with the support ledge 612l, where some of the twelve instances of the protrusion 616l are implemented differently from others of the twelve instances of the protrusion 616l. Put another way, within these embodiments of the present invention, a given one of the plurality of protrusions (such as, for example, a given one of the twelve instances of the protrusion 616l) is implemented in a first manner (such as, for example, a first shape and/or a first angle, etc.) and another one of the plurality of protrusions (such as, for example, another one of the twelve instances of the protrusion 616l) is implemented a second manner (such as, for example, a second shape and/or a second angle, etc.).
Furthermore, when selecting a particular design for the generally scalloped geometry 422, one can additionally take into account machining constraints, as well as constraints imposed by the use of specific equipment (for example, blow-molding equipment, etc.).
A technical effect of an embodiment of the present invention includes provision of a support ledge 512 that uses less material compared to prior art designs. In a given implementation, the material saving can be approximately 30% and as high as 50% of material that would have otherwise be used. In a given implementation, an additional technical effect attributable to material saving in the support ledge 512 can be an overall material savings that is approximately 3% of the overall preform 500 weight. Another technical effect of an embodiment of the present invention, includes provision of a support ledge 512 that is more efficiently cooled at least partially due to increased contact with metal. For example, if the preform 200 of
It should be noted that not each and every technical effect, in its entirety, needs to be enjoyed in each and every embodiment of the present invention.
Even though the foregoing description has used injection molding as an example for producing the preform, teachings of embodiments of the present invention are not so-limited. For example, in alternative examples, extrusion blow molding techniques can benefit from the teachings of the present invention.
Description of the non-limiting embodiments of the present inventions provides examples of the present invention, and these examples do not limit the scope of the present invention. It is to be expressly understood that the scope of the present invention is limited by the claims. The concepts described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present invention. Having thus described the non-limiting embodiments of the present invention, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims:
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA09/00153 | 2/13/2009 | WO | 00 | 8/20/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61039685 | Mar 2008 | US |
