Patent Publication Number: US-7897222-B2

Title: Preform and a mold stack for producing the preform

Description:
FIELD OF THE INVENTION 
     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 
     BACKGROUND OF THE INVENTION 
     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 blown 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 cavity and the 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 core piece. Thereafter, the molded article can be ejected off of the core piece by use of one or more ejection structure. Ejection structures are known to assist in removing the molded articles from the core halves. Examples of the ejection structures include stripper plates, stripper rings and neck rings, ejector pins, etc. 
     With reference to  FIG. 1 , a preform  100  is depicted, the preform  100  being an example of a typical prior art preform. The preform  100  consists of a neck portion  102 , a gate portion  106  and a body portion  104  extending between the neck portion  102  and the gate portion  106 . The gate portion  106  is associated with a substantially spherical shape that terminates in a vestige portion  108 . 
     U.S. Pat. No. 4,432,530 issued to Marcinek on Feb. 21, 1984 discloses a mold and core rod combination for forming a plastic parison for stretch/blowing into a plastic bottle comprising a core rod with an end mated to the mold so as to permit formation of a parison with a flat on the bottom and having a sharp taper from said flat to the sidewall of the parison. The core rod is preferably shaped to include a shoulder having a substantially straight outer wall at the mouth end of the parison mold, and constructed and arranged with the mold to permit deposit of additional plastic at the inner wall of the shoulder of the parison. The design of the mated mold and core rod combination is based on the recognition that in a continuous bottle forming process a particular area of the parison can be made hotter or cooler by increasing or decreasing the thickness of that area of the parison. Parisons formed with the disclosed mold-core rod combination permit a deeper and longer stretch of the parison without tearing or deformation of the parison bottom or deformation or wrinkling at the shoulder of the finished bottle while providing essential wall strength. 
     U.S. Pat. No. 4,959,006 issued to Feddersen et al. on Sep. 23, 1990 discloses a mold-core rod combination for producing a plastic preform for forming blow molded plastic bottles which comprises: a neck portion defining an opening; a tubular sidewall portion depending therefrom; and an integral base structure depending from the tubular sidewall portion to a closed end; the preform having an outside wall face and an inside wall face with one of these in the base structure having integrally formed thereon a plurality of filets, extending longitudinally of the preform and defining a continuous reinforcing ring of varying thickness spaced from the closed end and circumscribing the base structure, wherein the filets decrease progressively in width and radial thickness at least from the reinforcing ring toward the closed end. The preform is capable of forming a blow molded plastic bottle with a bottom portion having a continuous reinforcing ring of circumferentially continuous radially extending alterations in wall thickness with a regularly undulating cross-section along the circumference. Preferably the filets are integral with the inside wall face. 
     SUMMARY OF THE INVENTION 
     According to a first broad aspect of the present invention, there is provided a preform suitable for subsequent blow-molding. The preform comprises a neck portion; a gate portion; and a body portion extending between the neck portion and the gate portion; the gate portion being associated with a substantially conical shape. 
     According to a second broad aspect of the present invention, there is provided a mold stack. The mold stack comprises a core insert for defining an internal surface of a preform; a split mold insert pair for defining an external surface of a neck portion of the preform; a cavity insert for defining the external surface of a body portion of the preform; a gate insert for defining the external surface of a gate portion of the preform; the core insert and the gate insert being configured to cooperate, in use, to define the gate portion of the preform having a first substantially conical shape. 
     According to a third broad aspect of the present invention, there is provided a core insert for defining, in use, a portion of a preform, the preform including a neck portion, a gate portion and a body portion extending therebetween. The core insert comprises a first cavity defining portion having a gate defining portion which has substantially conical shape, the substantially conical shape so selected such that to homogenize angle of refraction of rays used during a re-heating stage of a blow-molding process of the preform within the gate portion. 
     According to a fourth broad aspect of the present invention, there is provided a gate insert for defining, in use, a portion of a preform, the preform including a neck portion, a gate portion and a body portion extending therebetween. The gate insert comprises a second cavity defining portion having a substantially inverted conical shape the substantially conical cone shape so selected such that to homogenize angle of refraction of rays used during a re-heating stage of a blow-molding process of the preform within the gate portion. 
     According to another broad aspect of the present invention, there is provided a method of producing at least a portion of a mold stack. The method comprises selecting a shape for a gate portion of a preform suitable for blow-molding, the shape so selected as to at least substantially homogenize angle of refraction of at least some of a set of rays during re-heating stage of a blow-molding process; manufacturing the at least a portion of the mold stack to include the shape. 
     According to yet another broad aspect of the present invention, there is provided preform suitable for subsequent blow-molding. The preform comprises a neck portion, a gate portion; and a body portion extending between the neck portion and the gate portion; the gate portion being associated a shape so selected such that to substantially homogenize angle of refraction of rays used during a re-heating stage of a blow-molding process. 
     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. 
    
    
     
       DESCRIPTION OF THE 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: 
         FIG. 1  depicts a cross section view of a preform  100  implemented in accordance with known techniques. 
         FIG. 2  schematically depicts the preform  100  of  FIG. 1  during a re-heating stage of a blow-molding process, implemented in accordance with known techniques. 
         FIG. 3  depicts a cross section view of a preform  300  implemented in accordance with a non-limiting embodiment of the present invention. 
         FIG. 4  depicts a cross section view of a preform  400  implemented in accordance with another non-limiting embodiment of the present invention. 
         FIG. 5  schematically depicts a portion of the preform  300  during the re-heating stage of the blow-molding process, similar to that of  FIG. 2 . 
         FIG. 6  depicts a cross-section view of a mold stack  600  configured to produce the preform  300  of  FIG. 3 , implemented according to a non-limiting embodiment of the present invention. 
         FIG. 7  is a side view of a core insert  602  of the mold stack  600  of  FIG. 6 , implemented according to a non-limiting embodiment of the present invention. 
         FIG. 8  is a cross-section view of a gate insert  608  of the mold stack  600  of  FIG. 6 , implemented according to a non-limiting embodiment of the present invention. 
         FIG. 9  depicts a cross section view of a preform  900  implemented in accordance with yet another non-limiting embodiment of the present invention. 
         FIG. 10  depicts a cross-section view of a portion of a mold stack  1000  configured to produce the preform  900  of  FIG. 9 , implemented according to a non-limiting embodiment of the present invention. 
     
    
    
     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. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Inventors have appreciated that there exists a problem with known designs of preforms  100 . With reference to  FIG. 2 , one such problem will now be illustrated in greater detail.  FIG. 2  schematically illustrates the preform  100  of  FIG. 1  during a re-heating stage of blow-molding process during which the preform  100  is formed into a final-shaped product. The re-heating stage is typically implemented during stretch-blow molding process, which is carried out subsequent to a molding operation to transform the preform  100  into a final-shaped article (such as a bottle and the like). The stretch-blow molding can be conveniently executed in a stretch-blow molding machine (not depicted). 
     Within the illustration of  FIG. 2 , there are provided a source of energy  202  and a reflector  204 . Generally speaking, the purpose of the source of energy  202  and the reflector  204  is to re-heat the preform  100  to a required temperature, the required temperature being sufficient to re-shape the so-heated preform  100  into the final-shaped article. 
     The source of energy  202  comprises a plurality of emitters  203 . The plurality of emitters  203  can be implemented in several variations, but within the specific non-limiting embodiment being presented herein, the plurality of emitters  203  can comprise a plurality of infrared light emitters. The plurality of emitters  203  can emit heat energy, such as for example, in a form of a set of infrared light rays  206  or the like. The set of infrared light rays  206  penetrates the preform  100  and, subsequently, gets reflected by the reflector  204  (such as, a mirror or the like), as a set of reflected infrared light rays  208 . The reflector  204  is typically used to increase efficiency of the re-heating stage. 
     In alternative non-limiting embodiment of the present invention the plurality of emitters  203  can be configured to emit energy at frequency other than infrared. Accordingly, the set of infrared light rays  206  will be referred herein below from time to time as rays  206  to capture other alternatives for the type of energy used. 
     Due, at least partially, to the spherical shape of the gate portion  106  and, as the result, variable angle of refraction of the set of infrared light rays  206 , which is particularly acute in the gate portion  106 , a sub-set of infrared light rays  210  is created. The sub-set of infrared light rays  210  is not reflected (or is reflected at a larger angle) by the reflector  204 , which significantly decreases the re-heating efficiency within the gate portion  106  and/or causes the re-heating to be uneven (i.e. variable) along the length of the gate portion  106 . One common solution has been to create a subset of the plurality of emitters  203  that are located proximate to the gate portion  106 , the subset of the plurality of emitters  203  being categorized by having higher power than the rest of the plurality of emitters  203 . As one can appreciate, this results in additional energy consumption and additional costs, which is not entirely satisfactory from the overall operation and environmental perspectives. 
     Reference is now made to  FIG. 3 , which depicts a preform  300  implemented according to a non-limiting embodiment of the present invention. The preform  300  consists of a neck portion  302 , a gate portion  306  and a body portion  304  extending between the neck portion  302  and the gate portion  306 . The neck portion  302  and the body portion  304  can be implemented in a substantially similar manner to the neck portion  102  and the gate portion  106  of the preform  100  of  FIG. 1 . 
     Within these embodiments of the present invention, the gate portion  306  is associated with a substantially conical shape that terminates in a vestige portion  308 . It is worthwhile noting that the vestige portion  308  delimits a lower terminal point of the conical shape of the gate portion  306 . Size of the vestige portion  308  can substantially correspond to size of an orifice of a hot runner nozzle (not depicted). Within the embodiment of  FIG. 3 , the gate portion  306  is associated with a substantially uniform wall thickness “W”, but this not need be so in every embodiment of the present invention (as will be illustrated herein below). 
     Within the embodiment of  FIG. 3 , the conical shape of the gate portion  306  is associated with an angle “α” defined between an imaginary central line  310  (the imaginary central line  310  passing through a longitudinal axis of the preform  300 ) and an internal surface of the conical shape of the gate portion  306 . In some embodiments of the present invention, the angle “α” can be so selected as to substantially homogenize the angle of refraction along the gate portion  306  during the re-heating stage of the blow-molding process. It has been found, for example, that the substantially conical shape of the gate portion  306  leads to more homogenous angle of refraction (and, therefore, more homogenous level of absorbance and re-heating) and, generally speaking, the smaller the angle “α” selected, the better homogeneity of angle of refraction (and, therefore, re-heating) is achieved. 
     In alternative non-limiting embodiments of the present invention, the angle “α” can be selected further taking into account rate of filling that the angle “α” will lead to and/or amount of material that will be used based on the angle “α”. As an example, the smaller the angle “α” selected, the smaller the pressure drop associated with the gate area of the molding cavity during the filling stage and, therefore, the faster the associated filling rates. By the same token, the smaller the angle “α” selected, the less material will be used to fill the gate area of the molding cavity. 
     Accordingly, in some embodiments of the present invention, the angle “α” can be selected taking into account some or all of (i) refraction index of a particular molding material being used, (ii) rate of filling that the angle “α” will lead to; and (iii) amount of material that will be used based on the angle “α”. Accordingly, within these embodiments of the present invention, the angle “α” can be calculated as function of all or some of (i) the refraction index of the molding material, (ii) weight of the molding material to be used (i.e. stretch function of the angle “α” and the wall thickness resultant from the angle “α”), (iii) the filling rate. 
     For example, in case of PET, the angle “α” can be selected from a range of between, for example, approximately 10 degrees and approximately 90 degrees. In a specific non-limiting embodiment of the present invention, in case of PET, the angle “α” can be selected from a range of between, for example, approximately 37 degrees and approximately 40 degrees. In another specific non-limiting embodiment of the present invention, in case of PET, the angle “α” can be selected from a range of between, for example, approximately 40 degrees and approximately 60 degrees. In a particular specific non-limiting example, the angle “α” used can be 37 degrees. Naturally, any other angle “α” based on the refraction index of the particular molding material or any other factors discussed herein above can be used. 
     Reference is now made to  FIG. 4 , which depicts a preform  400  implemented according to another non-limiting embodiment of the present invention. The preform  400  consists of a neck portion  402 , a gate portion  406  and a body portion  404  extending between the neck portion  402  and the gate portion  406 . The neck portion  402  and the body portion  404  can be implemented in a substantially similar manner to the neck portion  102  and the gate portion  106  of the preform  100  of  FIG. 1 . 
     The gate portion  406  is associated with a substantially conical shape that terminates in a vestige portion  408 . It is worthwhile noting that the vestige portion  408  delimits a lower terminal point of the conical shape of the gate portion  406 . Size of the vestige portion  408  substantially corresponds to size of an orifice of a hot runner nozzle (not depicted). 
     Within the embodiment of  FIG. 4 , the gate portion  406  is associated with an internal curvature section  410 , which is shown in an exaggerated view in  FIG. 4 . It is worthwhile noting that within the embodiment of  FIG. 4 , the gate portion  406  is associated with a substantially non-uniform wall thickness. More specifically, wall thickness is comparatively higher around the internal curvature section  410 . It is also worthwhile noting that even though the internal curvature section  410  is located on an internal surface opposite of the vestige portion  408  in the embodiment of  FIG. 4 , in other non-limiting embodiments of the present invention a similar curvature section can be located at other points (on the internal surface or an external surface) of the gate portion  406 . An example of this alternative placement may include, but is not limited to, to a location (on the internal surface or the external surface) where the gate portion  406  meets the body portion  404 , the location being depicted in  FIG. 4  at  420 . 
     With reference to  FIG. 6 , there is depicted a mold stack  600  implemented according to a non-limiting embodiment of the present invention. Within the illustration being presented herein, the mold stack  600  is configured to produce the preform  300  of  FIG. 3 . It is, however, expected that suitable modifications can be made by those of ordinary skill in the art to the mold stack  600  to produce the preform  400  of  FIG. 4 . 
     The mold stack  600  comprises a core insert  602 , a split mold insert pair  604 , a cavity insert  606  and a gate insert  608 . In use, the core insert  602 , the split mold insert pair  604 , the cavity insert  606  and the gate insert  608  define a molding cavity  609 , into which molding material (such as plasticized PET or other suitable molding material) can be injected to form the preform  300 . 
     With continued reference to  FIG. 6  and with brief reference to  FIG. 7 , the core insert  602  is configured to define, in use, an internal surface of the preform  300 . To that extent, the core insert  602  comprises a first cavity defining portion  603  configured to define a portion of the molding cavity  609  and an attachment portion  601  configured for attachment to a core plate (not depicted). In the embodiment depicted herein, the attachment portion  601  can be further configured to define a portion of the molding cavity  609 . In some embodiments of the present invention, the attachment portion  601  can be implemented as a lock ring. It should be noted that even though within the specific non-limiting embodiment being depicted herein, the first cavity defining portion  603  and the attachment portion  601  are implemented as structurally separate elements, in alternative non-limiting embodiments of the present invention, they can be implemented differently. For example, in alternative non-limiting embodiments of the present invention, the core insert  602  can be implemented without the lock ring and the like. 
     The first cavity defining portion  603  comprises a gate defining portion  610 . More specifically, the gate defining portion  610  has a substantially conical shape. Within some embodiments of the present invention, the gate defining portion  610  can be machined. However, in alternative non-limiting embodiments, other standard manufacturing methods can be used, such as cutting operation, milling operation or grinding operation. 
     With continued reference to  FIG. 6 , the split mold insert pair  604  is configured to define, in use, a portion of an external surface of the preform  300  and, more specifically, a portion of an external surface of the neck portion  302  of the preform  300 . The cavity insert  606  is configured to define, in use, a portion of an external surface of the preform  300  and, more specifically, a portion of an external surface of the body portion  304  of the preform  300 . 
     With continued reference to  FIG. 6  and with brief reference to  FIG. 8 , the gate insert  608  is configured to define, in use, a portion of an external surface of the preform  300 . To that extent, the gate insert  608  comprises a second cavity defining portion  612  configured to define a portion of an external surface of the gate portion  306  of the preform  300 . Shape of the second cavity defining portion  612  generally corresponds to the above-described gate portion  306 . More specifically, the second cavity defining portion  612  is associated with an inverted conical shape. 
     Within some embodiments of the present invention, the second cavity defining portion  612  can be machined. However, in alternative non-limiting embodiments, other manufacturing methods can be used, such as but not limited to standard drilling tools, grilling operation and the like. 
     The inverted conical shape of the second cavity defining portion  612  terminates in an extremity  802 , which substantially corresponds in diameter to an orifice (not separately numbered) of a nozzle receptacle  804  of the gate insert  608  (the nozzle receptacle  804  being configured to receive, in use, a hot runner nozzle (not depicted), which is omitted from the illustration for the sake of simplicity). 
     With reference to  FIG. 9 , a preform  900  implemented in accordance with another non-limiting embodiment of the present invention is depicted. The preform  900  consists of a neck portion  902 , a gate portion  906  and a body portion  904  extending between the neck portion  902  and the gate portion  906 . The neck portion  902  and the body portion  904  can be implemented in a substantially similar manner to the neck portion  102  and the gate portion  106  of the preform  100  of  FIG. 1 . 
     The gate portion  906  is associated with a substantially conical shape that terminates in a vestige portion  908 . Within the embodiment of  FIG. 9 , the conical shape of the gate portion  906  comprises a first cone  910  and a second cone  912 . Within these embodiments of the present invention, the first cone  910  is associated with a first angle “β” and the second cone  912  is associated with a second angle “γ”, the second angle “γ” being larger that the first angle “β”. 
     It is worthwhile noting that the vestige portion  908  delimits a lower terminal point of the second cone  912  (as well, as the overall conical shape of the gate portion  906 ). Size of the vestige portion  908  substantially corresponds to size of an orifice of a hot runner nozzle (not depicted). 
     With reference to  FIG. 10 , there is depicted a portion of a mold stack  1000  implemented according to a non-limiting embodiment of the present invention. Within the illustration being presented herein, the mold stack  1000  is configured to produce the preform  900  of  FIG. 9 . The mold stack  1000  can be substantially similar to the mold stack  600 , but for the specific differences discussed herein below. 
     Specifically, the mold stack  1000  comprises inter alia a core insert  1002  and a gate insert  1008 . The core insert  1002  is configured to define, in use, an internal surface of the preform  900 . To that extent, the core insert  1002  comprises a first cavity defining portion  1003  configured to define a portion of a molding cavity  1009 . The first cavity defining portion  1003  comprises a gate defining portion  1010 . The gate defining portion  1010  comprises a first cone portion  1010   a  and a second cone portion  1010   b.    
     The gate insert  1008  is configured to define, in use, a portion of an external surface of the preform  900 . To that extent, the gate insert  1008  comprises a second cavity defining portion  1012 . The second cavity defining portion  1012  comprises a first cone segment  1012   a  and a second cone segment  1012   b . In use, the first cone portion  1010   a  and the second cone segment  1012   b  cooperate to define the aforementioned first cone  910 . Similarly, the second cone portion  1010   b  and the first cone segment  1012   a  cooperate, in use, to define the aforementioned second cone  912 . 
     It should be noted that even though  FIG. 9  and  FIG. 10  depict the preform  900  and the mold stack  1000  for producing the preform  900 , the preform  900  having the gate portion  906  comprised of the first cone  910  and the second cone  912 , in alternative embodiments of the present invention, the gate portion  906  can be comprised of two or more cones. 
     Accordingly, according to embodiments of the present invention, there is provided the mold stack  600 ,  1000  and, more specifically, the core insert  602 ,  1002  and the gate insert  608 ,  1008  configured to produce the preform  300 ,  400 ,  900  that substantially homogenizes angle of refraction of at least some of the set of infrared light rays  206  during the re-heating stage of the blow-molding process and/or minimizes amount of material used to fill at least a portion of the preform  300 ,  400 ,  900  and/or increases the fill rate. 
     According to embodiments of the present invention, there is also provided a method for producing at least a portion of the mold stack  600 ,  1000 . More specifically, there is provided a method for producing one or both of the core insert  602 ,  1002  and the gate insert  608 ,  1008 . The method includes: 
     Selecting a shape for the gate portion  306 ,  406 ,  906  to be produced, the shape of the gate portion  306 ,  406 ,  906  so selected as to at least substantially homogenize angle of refraction of at least some of the set of infrared light rays  206  used during re-heating stage of the blow-molding process and, consequently, efficiency of re-heating. In some embodiments of the present invention, the selecting step additionally or alternatively includes, additionally, selecting the shape which also reduces weight of the molding material used and/or improves fill rates. In some embodiments of the present invention, the so-selected shape comprises a cone shape or a shape comprised of one or more cones. 
     Once the shape is selected, the method further includes manufacturing one or both of the core insert  602 ,  1002  and the gate insert  608 ,  1008 . Manufacturing can be implemented by using known techniques, such as a Computer Numerically Controlled (CNC) machining and the like. 
     Even though embodiments of the present invention have been described herein above using the cavity insert  606  and the gate insert  608  implemented as structurally separate members, in alternative non-limiting embodiments of the present invention, the cavity insert  606  and the gate insert  608  can be implemented as a structurally integral insert. Similarly, even though the preform  300 ,  400 ,  900  has been described as one suitable for stretch-blow molding; in alternative non-limiting embodiments of the present invention, the preform  300 ,  400 ,  900  can be subjected to other types of blowing processes. Furthermore, even though certain portions of the mold stack  600 ,  1000  have been described as inserts, in alternative embodiments of the present invention, these components can be implemented as structurally integral components of the mold plates and, accordingly, within the instant description the term “insert” is meant to include structurally integral components of the mold plates. 
     Operation of the mold stack  600  of  FIG. 6  can be implemented in a substantially similar manner to operation of the prior art mold stacks (not depicted) and, accordingly, only a brief description of the operation of the mold stack  600  will be presented herein. It is expected that those of ordinary skill in the art will be able to adapt these teachings for operation of the mold stack  1000  of  FIG. 10 . In  FIG. 6 , the mold stack  600  is shown in a mold closed position, within which it can be maintained by cooperating platens (ex. a moveable and a fixed platens) under tonnage applied by suitable means (such as, hydraulic, electric means and the like). 
     Within the mold closed configuration, molding material can be injected into the molding cavity  609  from a hot runner nozzle (not depicted) received within the nozzle receptacle  804 . How the molding material is distributed between an injection unit (not depicted) and the hot runner nozzle (not depicted) can be implemented in a conventional manner. The so-injected molding material is then solidified by means of, for example, coolant being circulated in or around the cavity insert  606 , and/or in or around the gate insert  608 , and/or in or around the split mold insert pair  604  and/or within the core insert  602 . 
     The mold stack  600  is then actuated into a mold-open position where the preform  200 ,  400 ,  900  can be de-molded from within the molding cavity  609 . Typically, when the mold stack  600  begins to open, the preform  200 ,  400 ,  900  stays on the core insert  602 . The split mold insert pair  604  is activated in a lateral direction (by any suitable means, such as cams, servo motors, etc.) to provide clearance for the neck portion  302 ,  402 ,  902 ). Movement of the split mold insert pair  604  in an operational direction causes the preform  200 ,  400 ,  900  to be removed from the core insert  602 . At this point, the mold stack  600  can be actuated into the mold closed condition and a new molding cycle can commence. 
     Even though embodiments of the present invention have been described with reference to injection molding and the mold stack  600 ,  1000  suitable for injection molding, this need not be so in every embodiment of the present invention. Accordingly, it is expected that teachings of the present invention can be adapted to other types of molding operations, such as extrusion molding, compression molding, compression injection molding and the like. 
     A technical effect of embodiments of the present invention may include provision of the preform  300 ,  400 ,  900  which substantially homogenizes angle of refraction of at least some of the set of infrared light rays  206  during re-heating stage of the blow-molding process within the gate portion  306 ,  406 ,  906 . This, in turn, may lead to increased re-heating efficiency of the gate portion  306 ,  406 ,  906  of the preform  300 ,  400 ,  900  at least partially due to more constant absorbance of the set of infrared light rays  206 , which can be attributed at least partially to more homogenous angle of refraction along the length of the gate insert  608 ,  1008  and/or decreased level of reflection. Another technical effect of embodiments of the present invention may include provision of the preform  300 ,  400 ,  900  which requires less material compared to the preform  100 . This, in turn, may lead to cost savings associated with savings associated with raw materials. Another technical effect of embodiments of the present invention may includes provision of the mold stack  600  for producing the preform  300 ,  400 ,  900 ; the mold stack  600  providing less of a pressure drop within a portion of the molding cavity  609 ,  1009  that defines the gate portion  306 ,  406 ,  906  of the preform  300 ,  400 ,  900 . This, in turn, may result in a faster fill process. It should be expressly understood that not all of the technical effects need to be realized in each and every embodiment of the present invention. 
     A particular technical effect associated with the increased re-heating efficiency of some of the embodiments of the present invention is best illustrated with reference to  FIG. 5 , which depicts a portion of the preform  300  of  FIG. 3  during the re-heating stage of the blow molding process. More specifically, a portion of the gate portion  306  is depicted. The source of energy  202  and the reflector  204  have been omitted from the illustration of  FIG. 5  for the sake of simplicity. As is clearly shown in  FIG. 5 , angle of refraction in the gate portion  306  is significantly homogenized and substantially no sub-set of rays (similar to the sub-set of infrared light rays  210 ) and, as such, re-heating efficiency is substantially maintained or improved in the gate portion  306 . Accordingly, a final-shaped article (not depicted) that is produced (for example, by means of blow-molding) from the preform  300 ,  400 ,  900  can be said to have a stretched gate area that suffers from less internal stress due, at least partially, to better re-heating efficiency. 
     Accordingly, it can be said that the preform  300 ,  400 ,  900  implemented in accordance with embodiments of the present invention, is associated with a shape that substantially homogenizes angle of refraction of at least some of the set of infrared light rays  206  (or other types of rays) around the gate portion  306 ,  406 ,  906  during the re-heating stage of the stretch-blow molding process. 
     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: