MXPA00008544A - Preform post-mold cooling method and apparatus - Google Patents

Abstract

The present invention relates to an improved method and apparatus for injection molding and cooling molded articles such as preforms so as to avoid crystallinity. The apparatus and method make use of a take-off plate for removing articles (48) from a mold, which plate may include heat transfer devices for cooling exterior surfaces of the molded articles or preforms (48), and a system for cooling (74) in a controlled manner interior surfaces of the molded articles or preforms (48).

Description

METHOD AND APPARATUS FOR COOLING A PREFORM AFTER MOLDING BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for molding and cooling plastic molded articles such as preforms made of single or multiple materials such as plastic resins. In particular, the invention describes a rapid process of injection molding wherein the molded articles, such as PET preforms, are ejected from the mold before the cooling or cooling step is completed. This is possible as a result of the use of a new cooling process and apparatus subsequent to the molding where the preforms are cooled internally by heat transfer by convection, after being removed from the mold and retained outside the mold area. The present invention also discloses an additional external cooling realized through heat transfer either by convection or by conduction, which is carried out at least partially simultaneous with the internal cooling. The proper cooling of the molded articles represents a very critical aspect of the injection molding process because it affects the quality of the article and affects the total injection cycle time. This becomes even more critical in applications where semicrystalline resins are used, such as injection molding or PET preforms. After injection, the PET resin remains in the mold cavity space for cooling for a sufficient period of time to prevent the formation of crystalline portions and to allow the preform to solidify before being ejected. Typically, two things happen if a preform of a mold is quickly ejected in order to reduce the cycle time of the injection process. The first time the preform does not cools uniformly. In most cases, the lower portion opposite the mold gate is crystallized. The amount of heat accumulated in the walls of the preforms during the injection process is still high enough to induce post-molding crystallinity, especially in the gate area of the preform. The gate area is a very critical point because the cooling of the mold in this portion is not effective enough and also because the resin in the space of the mold cavity is still in contact with the hot rod of the nozzle of hot slider infection. If this area of a preform remains crystalline above a certain size and depth, this will weaken the quality of a blown article. The second is that the preform will be too soft and therefore can be deformed during the following stages of handling. Another critical area of a preform is the neck finish portion which in many cases has a wall of thickness and therefore retains more heat than other portions. This neck portion needs active cooling after molding to prevent it from crystallizing. In addition, active cooling tends to make the neck sufficiently solid to withstand additional manipulations. Many attempts have been made in the past to improve the cooling efficiency of PET injection molding systems, but they have not resulted in significant improvements in the quality of the molded preforms or in a substantial reduction in cycle time. In this regard, reference is made to the United States patent for Valyi, which discloses an injection molding method wherein the molded preform is transferred to a first tempering mold for a first cooling step, and then to a second tempering mold, for a final cooling stage. Both tempering molds are similar to the injection mold and have an internal means for cooling their walls that makes contact with the preform during the cooling process. Valyi '905 does not disclose providing cooling devices located in the medium to transfer the preforms from the molding area or from the additional cooling devices where a fluid refrigerant circulates within the molded parison. The North American patent 4, 592,719 to Bellehache, discloses an injection molding method for manufacturing PET preforms wherein the molded preforms are removed from the injection cores by a first movable device comprising vacuum suction devices for maintaining the preforms and also comprising absorption of air (convection) to cool the outer surface of the preform. A second cooling device by Bellehache '719 is used together with a second movable device to further cool the interior of the preforms also by air absorption. See figure 22 in this. Bellehache '719 does not describe the blowing of cold air into a preform which has a significantly greater cooling effect with respect to the suction or absorption of ambient air and does not describe a means of cooling by heat transfer by conduction located in intimate contact with the wall of the preforms and a means of blowing air directed to the dome portion of the preforms. Bellehache suffers from many deficiencies that include lower cooling efficiency, less uniformity, a longer cooling time, and a high potential for deformation of the preform. U.S. Patent Nos. 5,176,871 and ,232,715 show a method and apparatus for cooling a preform. The molded preform is retained by the injection molding core outside the mold area. The mold core is cooled by a coolant that does not contact the molded preform. A cooling tube larger than the preform is placed around the preform to blow cooling air around the preform. The main problem with the apparatus and method shown in these patents is that the preform is retained in the mold core and this significantly increases the cycle time. In addition, internal cooling is not obtained by direct contact between the refrigerant and the preform. An additional reference is made to U.S. Patents 5,114,327, 5,232,641, 5,338,172 and 5,514,309 which describe a method of internal cooling of the preform using a liquid refrigerant. The preforms ejected from a mold are transferred to a preform carrier having a vacuum means for retaining the preforms in place without contacting the external wall of the preforms. However, the preform carrier does not have any cooling device. The cooling cores are further introduced into the preforms retained by the carrier and a cooling fluid is blown into the preforms to cool them. The coolant is further removed by the same vacuum medium that retains the preforms from the chamber surrounding the preforms. These patents do not describe the blowing of cold air into the preform, where the air freely leaves the preform after cooling. These patents also do not describe the simultaneous cooling of the preforms internally and externally, or a preform carrier having a cooling means. See figure 21 shown herein. An additional reference is made to the Japanese patent specification 7-171888 which describes a preform cooling apparatus and method. A robot carrier of molded preforms is used to transfer the preforms to a cooling station. The robot includes external cooling of the walls of the preform by thermal transfer by conduction using a water coolant. The cooling station comprises a first movable transfer robot having a rotating manual portion that includes a vacuum means for retaining the preforms, and also external cooling of the walls of the preforms by thermal transfer by conduction. The molded preforms are transferred from the robot carrier to the hand portion. The manual portion moves from position A to position B, where it rotates 90 ° in order to transfer the preforms (cooled until now only on the outside) to a cooling tool. The cooling tool has a means for retaining the preforms, devices for cooling the interior of the preforms in which the air is blown and devices for cooling the outside of the preforms, either by blowing air or by cooling with water. The internal cooling which is used is shown in Figures 19 and 20 herein. This patent does not disclose a cooling method wherein the internal and external cooling is performed as soon as possible from the moment the preforms are ejected from the mold into the carrier plate. It also does not describe the simultaneous internal and external cooling of the preforms while they are retained by the movable robot carrier. Therefore, this method of cooling is not fast enough and does not prevent the formation of crystallinity outside the mold. Figures 19 and 20 show known methods of internally cooling preforms wherein the cooling device is located outside the preform and is used to blow cold air into the preform. Because the air nozzle is located outside the preform, the cold air flow that enters will inevitably interfere and mix at least partially with the warm flow that comes out. This significantly reduces the cooling efficiency. If the cooling device is on the same axis as the preform, the solution of figure 19 is not effective because there is no air circulation in the preform. If the cooling device is displaced laterally as in Figure 20, internal circulation of air is obtained, but this is still inefficient because one side of the preform cools better and faster compared to the other. The coolant has a quasi-divergent flow profile with a non-symmetrical profile. This profile is very inefficient and does not allow concentrating the refrigerant fluid / gas towards the outgoing hatch or the dome portion.

BRIEF DESCRIPTION OF THE INVENTION A principal objective of the present invention is to provide a method and apparatus for producing preforms which have improved cooling efficiency. A further objective of the present invention is to provide a method and apparatus as in the foregoing, which produces preforms that have improved quality. A further objective of the present invention is to provide a method and apparatus as in the foregoing, which reduces the total cycle time. The above objects are obtained by the apparatus and method of the present invention. In one embodiment, the innovative method of molding and cooling of the present invention includes removing the preforms from the mold before the preforms are completely cooled inside the mold, ie, the preforms retain a certain amount of heat that can potentially crystallize the mold. outgoing gate portion, the neck finish portion or the entire preform; the retention of the preforms outside the molding area; and internally cooling the preforms by heat transfer by convection so that crystallization does not occur in any of these regions. In another embodiment, the innovative molding and cooling method of the present invention comprises removing the preforms from the mold before the preforms are completely cooled inside the mold, i.e., a certain amount of heat still remains that can potentially crystallize the gate portion. protruding, the finished neck portion or the complete preform; retention of the preforms outside the molding area; internally cooling the preforms by heat transfer by convection so that crystallization does not occur in any of the regions mentioned above, the cooling step comprises placing the refrigerant in direct contact with the preform; and externally cooling the preforms by heat transfer by convection so that crystallization does not occur in any of the regions mentioned above. The external cooling stage can be carried out simultaneously, at least partially simultaneously, or sequentially, with respect to the internal cooling stage. In yet another embodiment, the innovative molding and cooling method of the present invention comprises removing the preforms from the mold before the preforms are completely cooled inside the mold, i.e., a certain amount of heat still remains which can potentially crystallize the portion of projecting gate, the neck finish portion or the entire preform; retaining the preforms outside the molding area; the internal cooling of the preforms by heat transfer by convection so that crystallization does not occur in any of these regions, such internal cooling step comprises placing the refrigerant in direct contact with the preform; and externally cooling the preform by conduction heat transfer, so that crystallization does not occur in any of the regions mentioned above. The external cooling stage can be carried out simultaneously, at least partially simultaneously or sequentially with respect to internal cooling. In each of these embodiments, the preforms are ejected from the mold and retained external to the mold by means independent of the mold such as, for example, a removable separation plate. Such independent holding means can retain a batch of preforms molded the various batches of preforms simultaneously. When several batches are handled by the independent means, the batches will have different temperatures because they are molded at different times. In accordance with the present invention, the molded preforms will be cooled in different sequences internally and externally using the cooling method of the present invention. In each embodiment of the present invention, internal cooling is performed using a means, such as cooling bolts, which enter at least partially into the preform and circulate the refrigerant therein. The coolant is preferentially made by a quasi-symmetrical flow of a coolant supplied into the preform that can be directed towards the portions of the preforms that need more cooling than the others, such as the outgoing gate and the neck finish. In a preferred embodiment of the present invention, the refrigerant is directed towards the bottom of the dome portion of the preform so as to generate an annular flow of refrigerant. In certain embodiments of the present invention, the innovative internal cooling of the preforms is supplemented by external cooling which can be carried out in various ways. For example, external cooling may be performed on a pickup plate (single or multiple position) having an operational cooling medium using heat transfer either conductive (chilled water) or by convection (air / gas). It can also be done on the capture plate (single or multiple position) that does not have a cooling medium, so the preforms are only partially in contact with their supports. In this way, the cooling gas / air can be supplied by an independent cooling device to directly touch the outer surface of the preforms. In another additional embodiment, the preforms are retained in a pickup plate that has no cooling means and are cooled only internally by the new cooling bolts of the present invention. The innovative cooling solution of the present invention in one embodiment can be obtained by removing preforms or molded articles from the mold, retaining the preforms or molded articles in a robot acquisition plate having a system for cooling the outer surfaces of the molds. preforms or molded articles, and subsequently coupling the cooling medium into the preform or molded article to carry out the simultaneous cooling of the outer and inner surfaces. In accordance with the present invention; an additional cooling step is introduced whereby the temperature of the preform is reduced using heat transfer by convection, for example by the circulation of a refrigerant gas inside the preform. The method and apparatus according to the present invention, as discussed previously, can be used advantageously to avoid crystallization in the most critical areas of the preforms, specifically the lower part of the dome portion, where the outgoing gate is located. and the neck portion. In addition, the cooling method and apparatus of the present invention can be integrated into an injection blow molding machine, wherein cold preforms without crystallinity are additionally conditioned with respect to temperature and blown to form bottles. According to one aspect of the present invention, a method for preventing crystallization in an injection molded preform by improving the mold coolant, comprises injecting a molten material into a mold formed by two mold halves or plates, which, in an open mold position they are separated so as to define a molding area; cooling the molten material while the space of the mold cavity formed by the mold halves to a temperature substantially close to the glass vitreous transition temperature of the molten material, so that the molten articles can be mechanically handled outside the mold without suffering any geometric deformation; opening the mold halves by a distance sufficient to allow the carrier of the molded article to move between the two mold halves; eject molded articles from the mold and transfer them to the movable carrier; cooling the molded articles while they are in the movable carrier by heat transfer conduit to reduce the crystallinity, whereby the refrigerant is blown air; and internally further cooling the molded articles by convective heat transfer until each molded article is substantially free of any crystallized portion. The same method can be implemented using a movable carrier that includes a convective heat transfer medium for external cooling. According to one aspect of the present invention, the apparatus for forming a decrystallized injection molded article, comprises a mold having two mold halves, which can be moved between a closed mold position and an open mold position; means for injecting molten material into the mold while the mold halves are in the closed mold position; means for cooling the molten material in the cavity space formed by the mold halves to a temperature substantially close to the vitreous transition temperature of the molten material, so that the molded article can be mechanically handled outside the mold without undergoing any deformation geometric a means for opening the mold so that the mold halves are spaced a sufficient distance to allow the molded article carrier to move between the two mold halves; means for ejecting molded articles from the mold; a means for transferring the molded articles to a movable carrier; the carrier has a means for retaining the preforms and for cooling the molded articles by transfer heat conduction to reduce the crystallinity; and a means for further internally cooling the molded articles by convective heat transfer until each molded article, preferably the entire article, is substantially free of any crystallized portion, particularly in the gate area of the mold. The same method can be implemented using a movable carrier with a conductive heat transfer medium for external cooling.

As used herein, the terms "separation plate", "outlet plate" and "end of the arm tool" are used interchangeably and refer to the same structures. Other details of the method and apparatus of the present invention, as well as other objects and advantages attached thereto, are set forth in the following detailed description and the accompanying drawings, in which like reference numbers, describe similar elements.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing the temperature versus time of the preform during and after the induction stage; Figure 2 is a schematic representation of a preform in the mold; Figures 3 (a) and 3 (b) show the temperature gradient across the walls of a molded preform during cooling; Figure 3c shows the temperature profile along the walls of the preform; Figure 4 is a sectional view showing an injection mold of the prior art; Fig. 5 is a sectional view showing a movable robot including an arm tool end device (EOAT) positioned in the molding area between the stationary mold plates and. movable; Figures 6 (a) and 6 (b) are side views showing an embodiment of the present invention including a robot separation plate (or end of an arm tool, EOAT) and a frame holding cooling bolts; Figures 6 (c) and 6 (d) are front views of the embodiment of Figures 6 (a) and 6 (b); Figures 7 (a) -7 (d) show the frame and the cooling bolts according to a first embodiment of the present invention; Figures 8 (a) - (g) show various designs of cooling bolts according to the present invention; Figures 9 (a) and 9 (b) illustrate a more detailed view of the cooling bolts according to two embodiments of the present invention; Fig. 10 (a) shows a preform having crystallized zones as generated in the methods of the prior art; Figure 10 (d) shows a preform with no crystallized zones as a result after the method of the present invention; Figures 11 (a) -11 (1) show another embodiment of the frame and the cooling bolts, according to the present invention; Figure 12 is a sectional view of a system wherein air cooling channels are incorporated within the mold halves; Figures 13 (a) and 13 (b) are side views of another embodiment of the cooling system of the present invention; Fig. 14 is a top view of an injection molding system having another embodiment of the cooling system of the present invention; Figure 15 is a sectional view of another additional embodiment of the cooling system of the present invention showing the mechanism for cooling the interior of the molded articles attached to the separation plate; Figure 16 illustrates an embodiment of the present invention wherein a separation plate without a cooling means is used to remove the molded preforms from the molding area; Figure 17 illustrates the construction of an alternative cooling plasmid according to the present invention; Figures 18 (a) and (b) illustrate the construction of an additional alternative cooling bolt in accordance with the present invention; Figures 19 and 20 illustrate methods of the prior art for cooling the interior of a preform; Figure 21 illustrates another prior art system for cooling the interior and exterior of a preform; Figure 22 illustrates a prior art system that uses ambient air suction to cool a preform; and Figure 23 illustrates an alternative frame construction with cooling bolts on multiple surfaces in the frame.

DETAILED DESCRIPTION OF THE INVENTION With reference now to the drawings, Figure 1 is a graph showing the evolution of temperature versus time of the preform during and after the injection stage. Figure 2 is a schematic representation of a preform while still in the mold. As can be seen from this figure, cooling while in the mold is typically carried out by cooling tubes 12 and 14 placed within the mold cavity 16 and the mold core portions 18, respectively. As a result, the cooling is carried out from both sides of the preform 11. Furthermore, as shown in Figure 2, the mold cavity plate 16 typically has a gate region 20 where the bottom portion of the mold is formed. the dome portion 22 of the preform 11. The preform has a neck finish portion 13 which some times has a thick wall which is difficult to cool to avoid crystallinity. Figures 3 (a) and 3 (b) show the temperature gradient through the walls of a molded preform during cooling. Figure 3 (a) shows the temperature gradient inside the mold, while Figure 3 (b) shows the temperature gradient outside the mold. Figure 3 (c) shows the temperature profile along the walls of the preform. The temperature spike represents the temperature in the dome or in the protruding gate portion of the preform. Referring now to Figure 4, there is provided an injection mold which includes a stationary mold half or plate 32 having an array of mold cavities 34 and movable mold half or plate 36 having an array of cores 38 of mold. The mold cavity plate 32 is in fluid communication with a manifold plate (not shown) that receives molten material from an injection unit (not shown) of an injection molding machine. The mold cavities 34 receive the molten material from the hot slider nozzles (not shown), such as for example a valve gate nozzle (not shown), through the mold cavity gates 40. Each of the mold cavities is surrounded by a cooling means 42 for cooling the molten material in the cavity space formed by the mold core 38 and the mold cavity 34, when the mold plates 32 and 36 are in place. closed mold position. The cooling medium 42 is preferably formed by cooling channels embedded within the mold plate 32 for transporting a cooling fluid. As discussed previously, the mold cores 38 and the mold cavities 34 form in the closed mold position a plurality of mold cavity spaces (not shown) that are filled with fluid material through the mold gates 40 during the injection stage. The mold cores 38 also include a means 44 for cooling the molten material in the cavity space. The cooling medium 44 preferably comprises a cooling tube within each mold core. The mold core plate 36 further includes an ejector plate 46 which is used to remove the molded preforms 48 from the mold cores 38. The operation of the ejector plate 46 is well known in the prior art and does not form part of the present invention. In fact, the ejector plate 46 may comprise any suitable ejector plate known in the art. In accordance with the present invention, any plastic, metal or ceramic melt material can be injected into the space of the mold cavity and can be cooled in a desired article using the mold system of Figure 4. In a preferred embodiment of the present invention, the molten material is PET and the molded article is a preform. According to the present invention, however, the molded article can also be an elaborated preform of more than one material, such as for example virgin PET, recycled PET and an appropriate barrier material such as for example EVOH. As is known in the art, a preform is molded by closing the mold, injecting the molten material into the space of the cavity, initiating cooling of the space of the cavity, filling the space of the cavity, keeping the molten material under pressure, performing a final cooling in the mold, open the mold, eject the solidified articles or preforms from the cores, and transfer the articles or preforms to a separation plate. According to the present invention, in order to reduce the total cycle time, the residence time of the preform in the mold must be minimal so that the mold is capable of producing batches of preforms as quickly as possible. The problem with a reduced time of resistance in the mold is that the cooling time must be reduced, but in such a way that the molded articles or the preforms are sufficiently strong to withstand all the subsequent handling steps without deformation. A reduced cooling time is a problematic option because the articles or the preforms have not been cooled sufficiently and uniformly by the cooling means 42 and 44. The amount of heat retained by the article or preform after it cools within the mold for a short time and immediately after the mold opening is very significant and depends on the thickness of the molded article or the preform. This internal heat has the potential to generate crystallized portions in the projecting gate area or "dome portion" of the molded article or preform, the neck finish portion of the molded article or preform, or in the entire preform. to avoid crystallization of the molded article or preform, a very active cooling method should be used.When cooling, attention should be paid to the shrinkage control of the molded articles which may adversely affect their final dimensions. of a robot separation plate 60 which can be used in the cooling method of the present invention The separation plate 60 includes a plurality of hollow fasteners or holders 62 which can be water cooled tubes. Typical ones which can be used for the separation plate 60 are shown in the US Pat. U. No. 5,447,426 to Gessner et al. and in a US patent republication. No. RE 33,237 for Delfer, III, both of which are incorporated herein by reference. The operation, the mouth of a plurality, of fasteners 62 is aligned with the mold cores 38 of the mold plate 36. The transfer of the molded articles 48 to the fasteners 62 is carried out by operation of the ejector plate 46. According to the present invention, the separation plate 60 can be provided with several fasteners 62 equal to the number of mold cores 38 or a larger number of fasteners 62, such as a multiple of the number of mold cores, for example 3. to 4 times the number of mold cores. By having more fasteners 62 than the number of cores 38, it is possible to retain some of the molded articles for a longer time than in a single molding cycle and therefore increase the cooling time and at the same time maintain a high yield of molded articles. The method of the present invention can be carried out regardless of the relative number of molded articles retained by the fasteners 62. However, in the preferred embodiment of the invention, the robot separation plate 60 has many fasteners 62 which represent three times the number of cores 38. This means that the separation plate 60 does not always carry a number of preforms or molded articles equal to the number of fasteners 62. This also means that a single batch of preforms can be moved back more than one Once inside the mold area between the mold core and the cavity plates to catch other batches of molded articles, while being cooled by intimate contact between the hollow tubes 64 within the separation plate, tubes 64 which carry a cooling liquid such as water, and the outer wall of the shapes, as shown in greater detail in the the EU No. 5,447,426 mentioned above. The heat transfer between the tubes 64 and the hot molded articles released from the mold is carried out by conduction. More particularly, any solid material incorporating a cooling medium and intimately contacting the outer wall of the molded articles can be used to cool the molded articles. By using a cooling system based on heat transfer through conduction implemented through an intimate contact between the molded article or preform and cooling medium, the shape of the article or the preform is maintained without deformations or scrapes caused for the management. If desired, the conductive cooling means 64 used in the separation plate can be replaced by a convective heat transfer medium. Any suitable convective heat transfer means known in the art can be used with the separation plate 60 to carry out the cooling of the outer surfaces of the molded articles or the preforms carried by the separation plate 60. Referring now to Figures 6 (a) and 6 (b), an additional cooling device 70 is used in conjunction with the robot separation plate 60 to improve cooling efficiency after molding by allowing simultaneous cooling of the interior surfaces. and outside the molded articles or preforms by convective heat transfer and therefore the cycle time is reduced and the quality of the preforms is improved. The additional cooling device 70 includes an array of elongated cooling bolts 74 whose role is to supply a cooling fluid within the molded articles retained by the separation plate 60. In a preferred embodiment of the present invention, the cooling fluid is mainly directed and supplied directly into the dome portion 22 (projecting gate) of the molded article or preform, which portion has the greatest opportunity to become crystalline due to the reduction of the cooling time in the mold. The cooling fluid is introduced so that an annular flow pattern is generated. According to the present invention, the cooling fluid can be any suitable refrigerant, such as for example a liquid or a gas. In a preferred embodiment of the present invention, the cooling fluid is pressurized air supplied through a channel 90 located within the cooling pin 74. This aspect of the present invention is shown in greater detail in Figure 9 (a). Figure 9 (a) illustrates a cooling bolt 74 according to the present invention positioned within a preform or molded article 48 to be cooled. In order to create an optimum flow of cooling agent, the cooling bolt 74 is inserted deep into the preform 48 so that the coolant can reach the dome or the projecting gate portion 22. In addition, the cooling bolt 74 acts as an additional cooling core. The cooling pin 74 also contributes to the creation of an annular flow pattern which has a higher cooling potential as compared to other cooling flow patterns. In addition, by using the novel cooling bolt 74, the cold blowing air that enters and the hot air that comes out are completely separated and therefore the mixing of the two is avoided. As shown in Figure 9 (a), the cooling bolt 74 is centrally positioned within the preform or molded article, preferably so that the central axis 220 of the cooling bolt 74 is aligned with the central axis 222 of the preform . As you can see from this figure, the outer wall 224 of the cooling bolt 74 in an upper region UP is separated from the inner wall 226 of the preform by a distance D. Additionally, the outlet nozzle 92 of the cooling bolt 74 is separated from the interior wall 228 of the cooling bolt 74. the dome portion 22 by a distance d. In order to create the desired annular flow pattern of cooling fluid, it is preferred that the ratio of d: D be within the range of about 1: 1 to about 10: 1. It is also highly desirable that the outlet nozzle 92 of the cooling bolt be formed by a diverging nozzle construction. Although it is preferred to use a diverging nozzle for the outlet 92, it is possible to form the outlet 92 of a straight wall nozzle construction. Because the cooling bolt 74 moves deep into the preform and behaves similar to a cooling core also, the pattern of hot air that escapes freely escapes the preform and has an annular shape. Although a preferred construction has been shown for the cooling bolt of Figure 9 (a), as shown in Figures 8 (a) to 8 (g), 17 and 18, the cooling bolts 74 may have various sizes and sizes. ways to obtain various cooling effects. For example, as shown in Figure 8 (a), the lower portion LP of the cooling bolt may have a diameter D2 which is different from the diameter of O1 of an upper portion UP of the bolt. As shown in Figures 8 (a) to 8 (c), the upper portion UP of the bolts can have different shapes. With reference to Figure 8 (d), the cooling bolt 74 may have side outlets 82 for discharging cooling fluid onto the side walls of the molded article where crystallinity may occur. As shown in Figure 8 (e), the cooling bolt 74 can have helical grooves 84 for obtaining specialized cooling effects. Similarly in FIGS. 8 (f) and 8 (g), the cooling bolt 74 may have a plurality of stiffeners 86 spaced around its periphery or a plurality of contact elements 88. Figures 18a and 18b illustrate a cooling bolt 74 having a plurality of radial passages 230 for supplying coolant in areas of the preform other than the dome portion 22, such as the neck finish portion or the body portion. The radial conduits 230 may be spaced along the length of the cooling bolt so as to direct coolant against particular areas of a preform 48. The cooling bolts 74 may be fabricated of any suitable thermally insulating and thermally insulating material. If desired, as shown in Figure 17, the cooling bolt 74 can be made of a porous material 232 so that additional coolant can be dispersed in a very uniform manner in areas of a preform other than the dome or portion 22. of outgoing floodgate. In a preferred embodiment of the present invention, the design of the cooling bolt 74 is made to concentrate the maximum cooling on the projection gate or dome portion 22 of the molded article 48, and therefore actively focuses the cooling fluid to cool This region. In this way, molded articles such as free preforms of crystallized areas can be made in the projecting gate or dome portion 22.

An alternative bolt construction with a cold air blowing system which can be used in the apparatus of the present invention is illustrated in Figure 9 (b). As shown there, bolt 74 has a cold air blowing channel 90 having an outlet 92 for directing cold air against the inner surfaces of molded article 48, preferably the dome or the projecting gate portion 22 of the molded article. The channel 90 communicates with a source of cold air (not shown) via the inlet 94. The cooling pin 74 is further provided with a vacuum channel 96 for removing the cooling air from the interior of the molded article 48. The vacuum channel 96 can be connected to any desired vacuum source (not shown). As can be seen in Figure 9 (b), the cooling bolt 74 is mounted on a portion of a frame 98 by sliding pads 100, which are used for self-aligning the bolt, and a fastening means such as a nut 102. The nut 102 can be fixed to the element 104 which has an external threaded portion (not shown). Referring now to Figures 6 and 7, the arrangement of the cooling bolts 74 is mounted on a cooling frame 98 which can be made of a lightweight material such as aluminum. According to the present invention, the cooling frame 98 can operate in either vertical or horizontal position. In both cases, the frame 98 can move towards the separation plate 60 when the separation plate 60 reaches its final position outside the mold. Any suitable means known in the art can be used to move the frame 98 so that it advances at high speed so that the cooling bolts 74 can be immediately introduced into the molded article. In a preferred embodiment of the present invention, the frame 98 is moved using hydraulic cylinders 110. According to the present invention, the number of cooling bolts 74 may be equal to or less than the number of receptacles 62 in the separation plate 60. . In accordance with the present invention, the separation plate 60 is provided with a means for retaining the molded articles or preforms 48 within the receptacles 62 such as a suction means (not shown), and with a means for ejecting the preforms from the separation plate. The fastening means and the ejection means may be those described in US Pat. mentioned above No. 5,447,426 which has been incorporated herein by reference. As shown in Figs. 6 (c) and 6 (d), the cooling frame 98 is provided with a plurality of spaces 112. The spaces 112 allow the finally cooled molded articles or the preforms ejected from the separation plate 60. fall on a conveyor 114 for transportation away from the system. In a preferred embodiment of the present invention, the completely cooled preforms 48 are dropped on the conveyor 114 through the spaces 112 by laterally displacing the cooling bolts 74 relative to the receptacles 62 to maintain the preforms that must be ejected from them. the separation plate 60. This is the case when the cooling rack is in a horizontal position. When the cooling rack is in a vertical position, it does not interfere with the preforms that are dropped by the separation plate. Referring now to Figures 7 (a) and 7 (b), a first array of cooling bolts 74 is illustrated. As can be seen in Figure 7 (b), each of the cooling bolts 74 has cooling air passages 90 which communicate with a cooling air source (not shown) via the passage 122. Incorporated in the passage 122 there are numerous air valves 124 which can be used to regulate the flow of cooling air. In this way, variable quantities of cooling air can be supplied to the cooling bolts 74. Referring now to FIGS. 7 (c), it is also possible to directly provide each cooling bolt 74 with air from a cooling fluid source (not shown), via a single passage 126. Also, as shown in FIG. 7 (d), if desired, the passage 126 can be connected to the fluid conduit 120 in each of the cooling bolts via a flexible conduit 128.

According to one embodiment of the present invention, the cooling pins 74 enter the preforms retained by the separation plate 60 in some stages, and in each stage, the preforms are molded at different times and at different temperatures. In order to optimize the total cooling stage and avoid the waste of refrigerant, during the first cooling stage the preforms are very hot and therefore a maximum amount of cooling air is supplied by the bolts. In the second stage and in subsequent steps, the amount of cooling air directed by the bolts that engage the first molded preforms is substantially less than the amount directed toward the newly molded and hot preforms. In order to further optimize the cooling process, any suitable known temperature sensor, such as thermocouples, can be used to measure the temperature of the preforms before and after cooling so that adjustments can be made to the cooling rate without interrupt the molding core. In a preferred embodiment, thermocouples (not shown) are located connected to some cooling control means (not shown) in separation plate 60 adjacent to each preform. By monitoring the temperature of each preform, certain adjustments can be made to the amount of cooling air supplied to all of the cooling bolts 74 or to any of the cooling bolts 74. This can also compensate for any cooling inefficiency or lack of uniformity of the cooling medium by conduction which is located on the separation plate. Referring now to Figures 10 (a) and 10 (b), Figure 10 (a) shows the preform 48 in a sectional view, molded by a prior art system. As shown here, the preform 48 can have crystalline areas in four different zones including the dome portion 22 and the neck portion 13. On the other hand, Figure 10 (b) shows a preform 48, in a sectional view, which has been manufactured using the system of the present invention. As shown here, there are no areas of crystallinity. In figures 11 (a) to 11 (1) another embodiment of the present invention is shown, wherein the separation plate 60 'is always maintained in a vertical position during the entire molding cycle. This eliminates a complicated motor and makes the movement in and out of the mold space formed between the mold halves or mold plates 32 and 36 lighter and therefore faster, the cooling frame 98 'used in this system has an additional function and an additional movement. First of all, the bolts 74 'use cooling air to cool the molded articles or the preforms and suck air to extract the molded articles or preforms from the separation plate 60'. The preforms are held in the bolts 74 'by vacuum and removed from the tubes 62' within the separation plate 60 during a backward movement. The cooling frame 98 'has a movement to approach and move backward from the separation plate 60', and furthermore has a rotation to move from a vertical position to a horizontal parallel to a conveyor 114 'to allow the preforms to be ejected of the bolts 74 'to stop the vacuum. In accordance with the present invention, any suitable means known in the art for rotating the cooling frame 98 'with the bolts 74' may be used. According to a preferred embodiment of the invention shown in Figures 11 (a) to 11 (1), a stationary cam 130 is used as a very simple means to convert the translation of the frame into a rotation so that the preforms They are retained by the cooling rack and can fall on the conveyor 114 '. As shown in figure 11 (h), the cooling bolts 74 'can be coupled to the preforms by vacuum and removed from the separation plate 60. Then, the preforms are dropped from the bolts 74 'on a conveyor. The operation of the innovative cooling apparatus of the present invention can be understood from Figures 6 (a) to 6 (d). After the cooling process in the mold, which is shortened to the point where the articles or preforms reach a state of solidification that prevents their deformation, the mold is opened and the separation plate 60 moves within the mold area between the mold core plate 36 and the mold cavity plate 32. The relative movement between the mold core and the mold cavity plates can be performed in any manner known in the art using any suitable means (not shown) known in the art. After the separation plate 60 reaches the exterior of the molding position, the cooling pins 74 are coupled with the molded articles for cooling, especially in the dome area 22 of each article or preform. Although the separation plate 60 has been described with a cooling medium with water for cooling by conduction of the outer surfaces of the preforms within the supports 62, there are times when one wishes not to initiate the cooling of the outer surfaces when the Preforms are placed first inside the separation plate. For this purpose, a means for controlling the cooling inside the separation plate can be provided so that such cooling does not start until after the internal cooling of the preforms has begun or ended. For example, a suitable valve means (not shown) can be incorporated within the separation plate to prevent the flow of a cooling fluid within a desired point in time. In this way, the internal and external cooling of the preform can be carried out simultaneously, at least partially simultaneously, or sequentially.

Figure 16 illustrates another embodiment wherein the separation plate 60"without a cooling means is used to remove the molded preforms from the molding area." The separation plate 60"may have preform fasteners 62" in sufficient quantity to accommodate a single batch or multiple batches of preforms The preforms are retained by vacuum means (not shown) that through the openings 240 suck on the projection gate or the dome portion 22 of the preforms 48. The preforms are also retained by the preforms. 62"fasteners which can have any desired configuration that allows the preforms to be cooled directly using gas / cooling air. The fasteners 62"are preferably rigid enough to retain the preforms and have perforations or other openings 242 and 244, where the fasteners have no direct contact with the preforms, having this class of fasteners that only partially cover the outer surface of the preforms. the preforms, the preforms can be cooled on their outer surfaces, while they are additionally cooled internally by the cooling bolts 74. In this case, the cooling stage comprises the transfer of the preforms from the mold to the plate 60" separation, the movement of the pick-up plate 60"out of the molding area, to the cooling area which is adjacent to the molding area." In the cooling area, the preforms 48 are cooled internally using the frame 98 and the pins 74 of cooling that enter at least partially into the preforms At the same time, the preforms 48 retained by The separation plate 60"has its outer surfaces cooled convectively by an additional cooling station 250 which blows a cooling fluid towards the preform holders. As shown in Figure 16, the additional cooling station 250 has a plurality of nozzles 252, 254 and 256 for blowing coolant to the outer surfaces of the preforms. The nozzles 252, 254 and 256 blow cooling fluid through the windows 258 in the separation plate 60"and on the outer surface of the preforms via the windows or openings 242 and 244 in the holders of the preform. , 254 and 256 blow cooling fluid through the openings 242 and 244 in the preform holders 62"and on the outer surface of the preform. Although it has been demonstrated that the additional cooling station 250 having nozzles for cooling two preforms, it is recognized that in fact the cooling station 250 can have as many nozzles as needed to cool the outer surfaces of any desired quantity of preforms. The use of the additional cooling station 250 allows the preforms 48 to be cooled simultaneously inside and outside by using a cooling means that is independent of the separation plate 60. This approach makes the separation plate 60"very light, Very fast and easy to service. If desired, the preform holders 62 can hold the preforms only around the neck portion, thus leaving a window more open so that the blown cooling fluid cools the outer portion of the preforms. of the invention, the separation plate may include an external cooling medium using blown air or may not include a cooling medium In both cases, internal cooling is obtained using the novel cooling method and apparatus of the present invention. The innovative cooling method and apparatus of the present invention are extremely beneficial for cooling molded preforms and high cavitation molds.It is well known that the temperature of molten resin flowing through a mold varies substantially for various reasons, including: (a) non-uniform heating of the hot slide manifold; (b) formation of boundary layers within the manifold fusion channels; (c) non-uniform cooling of the mold cavity; and (d) insufficient cooling in the mold gate area. A sequence of temperature variations through the mold is that the cooling time must be adjusted locally so that the hotter preforms cool down before any crystallinity occurs in the final preforms. In order to avoid the formation of crystallized zones, the cooling system of the present invention is capable of providing a different implement pattern that can be adjusted according to the temperature signature of each mold. The sensors in the separation plate 60 can be provided to regulate the amount of cooling from each cooling bolt 74. Another consequence of uneven temperature inside the mold is that in most cases the projecting gate area located in the dome section 22 of the preforms is the hottest part of the molded preform. Because this protruding gate portion cools more slowly in the closed position of the mold, there is a likelihood that this portion will be highly crystalline if the cooling in the mold is too long or if no additional cooling is provided outside the mold. According to the present invention, the cooling bolts 74 that blow cold air into the preform immediately adjacent to the projecting gate area is a novel operation that very efficiently avoids the formation of crystallized areas in the preform. The innovative cooling method and apparatus of the present invention are also beneficial to compensate for the cooling inefficiency of the separation plate. It may happen that, due to imperfect contact between the hot molded article and the cooling tube, the temperature of the molded article maintained by the separation plate may vary across the plate. In accordance with the present invention, the temperature sensors located in the separation plate or in the cooling rack can be used to provide information regarding the cooling control unit that varies the amount of cooling fluid directed to each preform. The adaptive cooling approach mentioned so far is also beneficial because it takes into account the fact that the temperature pattern of the molded preforms can vary during the day, the function of the specific resin used, the function of the adjustments of the machine or due to local variations in the thickness of the preforms caused by improper actuation of the valve stem in the hot sliding nozzle or due to an irregular displacement of the core and the mold cavities. These situations are not predictable or easy to fix. However, the present invention provides a mechanism for adjusting the post-molding cooling step for each cavity based on the temperature of each molded article or preform. A significant reduction in cycle time can be obtained for the benefit of increasing post-molding cooling time by simplifying the design and movements of the separation plate and the cooling rack. This should take into consideration a very critical assembly, maintenance and operation constraints such as stiffness, precision of movement, alignment between the cooling bolts and molded articles or preforms in the separation plate and vibrations. In addition, the position of the cooling frame with the bolts must be decided in such a way as to reduce the "printed footprint" of the entire machine. In this regard, reference is made to Figures 13 (a) and 13 (b) which show another embodiment of the present invention wherein the separation plate 60 remains in a vertical position during the additional air cooling stage., that is, parallel to the mold plates 32 and 36. The cooling frame 98 is moved to the separation plate 60 and cooling bolts 74 that enter the molded articles or preforms 48. After all the preforms are cooled, the cooling frame 98 retracts, the plate 60 of The separation is rotated 90 ° and placed parallel to the conveyor 114, and then the cooled preforms are removed from the plate 60. This solution simplifies the design of the cooling frame which does not need a means of rotation and a means to prevent its interference in the preforms ejected from the plate. Additional reference is made to Figure 14 which shows another embodiment of the invention wherein the robot separation plate 60 comprises an additional translation means 150 for moving the preforms 48 along an axis parallel to its axis of revolution. This further movement of the preforms 48 simplifies the cooling frame 98 which remains substantially stationary during the cooling process. As shown in Figure 14, the separation plate 60 or other means for retaining the preforms, are transposed along the X axis towards the stationary cooling frame 98. After the cooling step, the separation plate 60 is rotated 90 ° so that it faces the conveyor 114 and therefore the chilled preforms are ejected. Additional reference is made to Figure 15, which shows a novel cooling medium by air attached to the separation plate 60. The solution shown in this figure eliminates the need for a separate frame to hold the cooling bolts and therefore reduces the size of the cooling system and likewise that of the injection molding machine. The new cooling bolts 174 have an approximate U-shape and can be moved all together parallel to the preforms 48 so that they can be inserted into the preforms and moved out of the preforms using a thin strip 176 driven by the piston BB or any other known means. The bolts 174 can also rotate about an axis "A" parallel to the preform, so that they can be placed on, or removed from, axial alignment with the preforms. This simultaneous rotation of all bolts 174 can be obtained using any suitable means known in the art. According to the invention, the U-shaped cooling bolts 174 have an arm "A" which enters the preform, an arm "C" parallel to the arm "A" which is used to move the arm "A", and an arm "B" that connects arm "A" with arm "C". The rotation of the bolts around the axis A of the arm "C" can be done in various ways. As shown in Figure 15, this can be accomplished using an elongated grid 178, operated by a piston AA which is in engagement with the pinions 180 attached to the "C" arm of each cooling bolt. The same rotation can be made using a frictional medium, one in the translation and another in the rotation. During the transfer of the preforms 48 from the cores 38 to the cooling tubes 62 of the separation plate 60, the U-shaped cooling bolts 174 can be "parked" in a dedicated position located adjacent to each cooling tube 62 , so that they do not interfere with the preforms in movement and less space is needed to open the mold. Immediately after the preforms 98 are retained in the separation plate 60, the cooling pins 174 attached to the plate 60 are moved forward by the piston BB and the strip 176, and then reach a certain height which allows the arm "A" is in the upper part of the preform, and rotates in axial alignment with the preforms that are finally introduced into the preforms by the retraction of the piston BB. Permanent contact between strip 176 and each arm "C" is provided by a helical spring 182 which operates against flange 181 or any other appropriate means. A flexible tube 184 is used to supply blown air to each cooling bolt through arm "C". This design of the cooling bolts attached to the separation plate has the following advantages: simplifies and reduces the size of the cooling system, it improves the cooling speed because the inner cooling starts immediately after the preforms are in the separation plate, the inner cooling can be carried out during the movement of the separation plate and in a practically continuous way as long as the preforms are also cooled by the separation plate. During the ejection of the cooled preforms, the cooling bolts must rotate back to their initial position so that they are no longer aligned with the preforms. An additional reference is made to Figure 12, which shows an air cooling medium comprising cooling channels 210 incorporated in the mold halves 32, 36 that allow the cooling of the preforms maintained by the mold cores during and immediately after the opening of the mold and before the separation plate between the molding area. This cooling step will further solidify the preform before the separation plate is placed in the mold area and before it is transferred to the separation plate.

In accordance with another aspect of the present invention, it can be easily understood from other drawings, in this application, that the robot and the separation plate retain only a single batch of preforms. After the injection steps, the separation plate is parked outside the mold area and cooling air or chilled air is blown into each preform from the cooling bolts. The chilled preforms are ejected from the separation plate which will be placed back into the molding area without transporting any preforms. Figure 23 illustrates an alternative construction of the frame 98 for holding the cooling bolts 74. As shown in this figure, the frame 98 may have cooling bolts 74 on two opposite surfaces. In addition, the frame can rotate about a first axis 300 and a second axis 302 which are perpendicular to the first axis 300. Any suitable means (not shown) known in the art for rotating the frame 98 around the axes can be used. 300 and 302. By providing this type of construction, it is possible to have a first set of cooling bolts 74 which engage the preforms 48 in a separation plate 60 and start the internal cooling of the preforms. The preforms 48 can then be transferred out of the fasteners 62 in the separation plate 60 onto the bolts 74. The frame 98 can then rotate about one or more shafts 300 and 302, while internal cooling of the shafts is carried out. preforms 48 by pins 74. After the first set of preforms has reached the left position shown in Figure 23, a second set of cooling pins 74 can be coupled with a second set of preforms 48 which are held in the separation plate 60. If desired, the left set of preforms 48 may have their outer surfaces convectively cooled using a cooling station 304 having a plurality of nozzles (not shown) for blowing cold air onto the outer surfaces. If desired, the frame 98 may have a preform retention plate 308 attached thereto.

Claims (69)

1. A method for producing a molded article, comprising the steps of: removing a molded article from an injection mold while the article retains a quantity of heat; avoiding crystallization in a dome portion of the molded article by contacting the dome portion with a flow of cooling fluid; and the contacting step comprises placing a cooling bolt having a fluid nozzle in a tip portion within the molded article in close proximity to the dome portion and expelling the cooling fluid through the tip portion directly over the portion of dome.

2. The method as described in claim 1, wherein the expulsion step comprises ejecting the cooling fluid so as to generate an annular flow of the cooling fluid within the dome portion of the molded article.

3. The method as described in claim 1, further comprising: the placement step comprises placing a cooling bolt having at least one internal passage and an outlet nozzle at the tip portion within the interior of the molded article; and separating the outlet nozzle a distance D from an interior wall surface sufficient to create an annular flow of the cooling fluid.

4. The method as described in claim 3, wherein an outer surface of the tip portion is separated from the dome portion of the molded article by a distance d and the step of separating the outlet nozzle comprises separating the nozzle from output so that the ratio d: D is in the range of about 1: 1 to about 10 10: 1.

5. The method as described in claim 4, further comprising: connecting at least one internal passage to a source of pressurized and cooled air; and the stage of 15 ejection comprises blowing cooled air over the dome portion.

6. The method as described in claim 1, further comprising: the positioning step further comprises 20 forming an annular space between the interior surfaces of the molded article and cooling bolt; and allowing the cooling fluid to flow through the annular space and escape to the environment.

7. The method as described in claim 1, further comprising cooling the outer portions of the molded article after the molded article has been removed from the mold.

8. The method as recited in claim 7, wherein the step of cooling the outer portion is performed simultaneously, at least partially simultaneously, or sequentially with the ejection step.

9. The method as recited in claim 7, wherein the cooling step of the outer portion comprises cooling the outer portions by heat conduction or heat convection transfer.

10. The method as described in claim 7, wherein the step of cooling the outer portion comprises placing the outer portions of the molded article in direct contact with the cooled surface.

11. The method as described in claim 7, further comprising: providing a separation plate having a fastener for the molded article, the fastener has a plurality of openings for exposing the outer surfaces of the molded article to a flow of cooling fluid; the removal step comprises loading the molded article into the holder on the separation plate; and the outer cooling step comprises providing a plate in the form of cooling with a plurality of nozzles and blowing a cooling fluid through the nozzles and through the openings in the support onto the outer surfaces of the molded article.

12. The method as described in claim 1, further comprising: forming a plurality of molded articles in the mold; and the removal step comprises providing a carrier having receptacles for the molded articles and transferring such molded articles to the receptacles.

13. The method as described in claim 12, further comprising cooling the outer portions of the molded articles while the molded articles are in the receptacles and are transported by the carrier to a position outside the mold.

14. The method as described in claim 12, further comprising: providing a frame having a plurality of cooling bolts; and the contacting step comprises relatively moving the frame and the carrier, so as to insert the cooling bolts into the interiors of the molded articles immediately after the carrier and the molded articles have been removed from between the halves of the molded articles. mold mold.

15. The method as described in claim 14, wherein the extrusion step comprises blowing cooling fluid through the bolts onto the dome portions of the molded articles.

16. The method as described in claim 12, further comprising: the step of forming the molded article comprises forming a plurality of preforms; and subsequently blowing each of the preforms into final decrystallized articles.

17. The method as described in claim 1, further comprising: forming a first set of molded articles in a mold formed by two mold halves; and the removal step comprises providing a carrier having a plurality of receptacles for receiving the molded articles, moving the carrier to a first position between the two mold halves, transferring the molded articles to receptacles while the carrier is in the first position, and moving the carrier with the molded articles in receptacles to a second position outside the mold.

18. The method as described in claim 17, further comprising: the ejection step comprises directing a flow of the cooling fluid into the dome portion of each of the molded articles of the first assembly via a plurality of cooling bolts of so that the crystallization of the dome portion of each molded article is substantially prevented; and the steering stage begins when the carrier leaves the mold and moves to the second position.

19. The method as described in claim 18, further comprising: providing a frame having a plurality of cooling bolts; Relatively moving the carrier frame so that it inserts the cooling bolts into the interior of the molded articles forming a first assembly prior to the ejection step.

20. The method as described in claim 18, further comprising: detecting the temperature of each of the molded articles; and adjusting the flow of cooling fluid inside the molded articles in response to the detected temperatures, the adjustment step comprises adjusting the valve means associated with the cooling bolts so as to adjust the flow of refrigerant fluid through of the individual cooling bolts.

21. The method as recited in claim 18, wherein the steering step further comprises directing the cooling fluid within the interiors of the molded articles to a first flow rate during a first portion of a cooling cycle, and to a second slower flow rate during a second portion of the cooling cycle.

22. The method as described in claim 18, further comprising: extracting the cooling bolts from the interior of the molded articles; move the carrier back to the first position; transferring a second set of molded articles into the receptacles, into the carrier while the first set of molded articles is still inside the receptacles in the carrier; returning the carrier with the first and second sets of molded articles to the second position; and inserting the cooling bolts into the interiors of the molded articles in the second assembly after the carrier leaves the mold and moves to the second position.

23. The method as described in claim 22, further comprising cooling the second set of molded articles by directing a flow of cooling fluid into the dome portion of each of the molded articles of the second assembly via the cooling bolts, in a manner that substantially prevents crystallization in the dome portion of each molded article.

24. The method as described in claim 23, further comprising: ejecting the molded articles from the first assembly onto a transfer device.

25. The method as described in claim 19, further comprising: providing a cooling station having a plurality of nozzles connected to a source of cooling fluid; place the cooling station adjacent to the carrier; and detecting cooling fluid on the exterior surfaces of the molded articles by blowing to cool the fluid through the openings in the receptacles on the outer surfaces.

26. The method as described in claim 25, further comprising applying a vacuum to each of the molded articles to hold the articles in the receptacles during the external cooling stage.

27. An apparatus for producing a molded article, which comprises: a means for removing the molded article from the mold while the molded article retains a quantity of heat; a means for preventing crystallization in the dome portion of the molded article by contacting the dome portion with a flow of cooling fluid; and the crystallization prevention means comprises a cooling bolt having a fluid nozzle in a tip portion positioned within the molded article in close proximity to the dome portion, whereby the cooling fluid is expelled through the nozzle in the tip portion directly over the dome portion.

28. The apparatus as described in claim 27, wherein the tip portion of the cooling bolt is sufficiently close to the dome portion so as to generate an annular flow of cooling fluid within the dome portion of the molded article.

29. The apparatus as described in claim 27, wherein the cooling bolt blows pressurized air cooled on the dome portion.

30. The apparatus as described in claim 29, wherein the cooling bolt has at least one passage communicating with a cooled air source.

31. The apparatus as described in claim 27, wherein the cooling bolt has a central axis aligned with the central axis of the molded article and is separated from the interior surfaces of the molded article by a distance D, so as to form a space annular between the inner surfaces and the cooling bolt, and wherein the cooling bolt has an outlet nozzle and the outlet nozzle is separated from the interior surface of the dome portion by a distance d, and wherein the ratio of d: D is in the range of about 1: 1 to about 10: 1, so that an annular flow of the cooling fluid is generated.

32. The apparatus as described in claim 31, wherein the outlet nozzle is formed by a divergent nozzle structure; and wherein the cooling fluid circulates through the annular space and escapes to the ambient atmosphere.

33. The apparatus as described in claim 27, further comprising a removal means comprising a carrier having a receptacle for receiving the molded article.

34. The apparatus as described in claim 33, wherein the carrier has a means for cooling the outer surfaces of the molded article by conduction, while the molded article is inside the receptacle so that the shape of the article is maintained without any deformation. .

35. The apparatus as described in claim 33, wherein the receptacle comprises a tube cooled with water within the carrier.

36. The apparatus as described in claim 33, wherein: the mold comprises a mold formed by two mold halves; the carrier is indexed between a first intermediate position to the mold halves, and a second position outwardly of the mold halves; and the mold has a means for cooling the molded article to a temperature substantially close to the crystalline vitreous transition temperature so that the molded article can be handled out of the mold without undergoing any geometric deformation.

37. The apparatus as described in claim 36, wherein the cooling bolt is mounted on a frame which moves relative to, and independently of, the carrier.

38. The apparatus as described in claim 37, wherein the carrier includes a plurality of receptacles for holding a plurality of molded articles and a crystallization prevention means comprising a plurality of cooling pins counted in the frame.

39. The apparatus as described in claim 38, wherein the frame includes a plurality of openings to allow the chilled of the molded articles to be expelled from the carrier while the cooling pins are coupled with some of the molded articles which have not completed a cooling cycle.

40. The apparatus as described in claim 38, further comprising: the frame has a passage connected to a source of cooling fluid; the cooling bolts communicate each with a passage; and a valve means for supplying regulated amounts of the cooling fluid to each cooling bolt, whereby the amount of cooling fluid supplied to each individual cooling bolt is regulated by the valve means according to a particular stage of a cooling cycle.

41. The apparatus as described in claim 40, further comprising a means for detecting the temperature of each molded article and a means for controlling the amount of fluid supplied to each cooling bolt in response to the detected temperatures of the molded articles.

42. The apparatus as described in claim 38, further comprising: each cooling bolt includes a means for removing the respective one of the molded articles from its receptacle; and means for moving the frame between a first position and a second position, wherein the molded articles are expelled from the cooling bolts by decreasing the operation of the removal means.

43. The apparatus as described in claim 42, wherein the frame moving means comprises means for converting the translation of the frame into frame rotation.

44. The apparatus as described in claim 38, wherein the carrier includes a means for maintaining the molded articles within the receptacles and a means for ejecting the molded articles from the receptacles after the cooling has been completed.

45. The apparatus as described in claim 38, wherein each of the cooling bolts has a first portion with a first diameter, and a second portion with a second diameter, a second diameter which is different from the first diameter.

46. The apparatus as described in claim 38, wherein each of the cooling bolts has lateral outlets for discharging the cooling fluid on the side walls of the molded articles where crystallinity occurs.

47. The apparatus as described in claim 38, wherein each of the cooling bolts has helical grooves on its outer surface.

48. The apparatus as described in claim 38, wherein each of the cooling bolts has a plurality of spaced reinforcements around its periphery.

49. The apparatus as described in claim 38, wherein each of the cooling bolts has a plurality of contact elements spaced around its periphery.

50. The apparatus as described in claim 38, wherein each of the cooling bolts concentrates a maximum cooling in a dome portion of the respective molded article in which it is placed.

51. The apparatus as described in claim 38, wherein each of the cooling bolts includes a means for removing cooling fluid from the interior of the molded article.

52. The apparatus as described in claim 38, further comprising: each cooling bolt has an approximate U-shape and can be moved between a first position, wherein a U-shaped cooling bolt arm is positioned within the article molded, and a second position wherein an arm of the molded article is removed; means for axially moving each U-bolt between the first and second positions; and a means for rotating each U-shaped cooling bolt to a third position wherein one arm of each U-shaped cooling bolt does not interfere with the removal of the molded articles from the carrier.

53. The apparatus as described in claim 38, wherein each of the cooling bolts is formed from a porous material so that cooling fluid can be applied in a substantially uniform manner to multiple portions of the molded article.

54. The apparatus as described in claim 38, wherein each of the cooling bolts has a plurality of radial conduits for applying coolant to multiple portions of the molded article.

55. The apparatus as described in claim 38, further comprising means external to the carrier for blowing a cooling fluid onto the outer surfaces of the molded article.

56. The apparatus as described in claim 55, wherein the carrier has a receptacle for holding the molded article and the receptacle has openings in its lower side walls, and wherein the external blowing means blows cooling fluid through the openings on the outer surfaces.

57. The apparatus as described in claim 38, further comprising means external to the carrier for directing cooling fluid against the outer surfaces of the molded articles.

58. The apparatus as described in claim 57, wherein each of the receptacles has openings in its side and bottom walls and wherein the external cooling fluid directing means blows cooling fluid through the openings in the exterior surfaces.

59. The apparatus as described in claim 38, further comprising a vacuum means for maintaining each of the molded articles in one of the respective receptacles.

60. A method for forming a molded article, comprising the steps of: removing a molded article from a mold while the article retains sufficient heat to cause crystallinity in the molded article; inserting a cooling bolt into the molded article; and creating an annular flow of cooling fluid within a dome portion of the molded article so that crystallization is prevented at least within the dome portion.

61. The method as described in claim 60, further comprising: aligning a central shaft of cooling bolt with a central axis of the molded article, such that an outer surface of the cooling bolt is a distance D from the inner surface of the article molded; separating an outlet nozzle from the cooling bolt a distance d from an interior surface of the dome portion; and the annular flow creation step comprises positioning the cooling bolt so that the ratio of d: D is in the range of about 1: 1 to about 10: 1.

62. The method as described in claim 60, further comprising cooling the outer surfaces of the molded article by conductive heat transfer or converting heat transfer, and the outdoor cooling step occurring simultaneously with, at least partially, simultaneously , with, or sequentially with, an annular flow creation stage.

63. An apparatus for producing a molded article, comprising: means for removing a molded article from a mold while the molded article retains sufficient heat to cause crystallinity in the molded article; and a means for generating an annular flow of cooling fluid within a dome portion of the molded article so that crystallization is prevented at least within the dome portion.

64. The apparatus as described in claim 63, wherein the annular flow creating means comprises a cooling bolt positioned within the molded article, the cooling bolt has a central axis aligned with a central axis of the molded article, and a outer surface which is separated from an inner surface of the molded article by a distance D and the cooling bolt has an outlet nozzle which is separated from an inner surface of the dome portion of the molded article by a distance d, and in where the ratio of d: D is in the range of about 1: 1 to about 10: 1, so that an annular flow is generated.

65. The apparatus as described in claim 64, wherein the outlet nozzle is formed by a diverging nozzle structure.

66. The apparatus as described in claim 63, further comprising means for cooling the outer surfaces of the molded article by conductive heat transfer, or convective heat transfer.

67. A method for producing a molded article, comprising the steps of: removing a molded article in a mold while the article retains a quantity of heat; the removal step comprises placing the molded article in a separation device and extracting the separation device with the article molded therein from between the mold halves of the mold; inserting a cooling bolt into the molded article immediately after the separation device and the article has been extracted from between the mold halves, the insertion step comprises placing a tip portion of the cooling bolt in close proximity to a dome portion of the molded article; and applying a flow of cooling fluid directly to the dome portion via the tip portion of the cooling bolt.

68. An apparatus for producing a molded article, which comprises: means for removing a molded article from a mold while the molded article retains a certain amount of heat; the removal means comprises a separating device for receiving the molded article and for extracting the molded article from between the mold halves of the mold; means for inserting a cooling bolt into the molded article immediately after the separation device and the article has been extracted from between the mold halves, the insertion means inserts a tip portion of the cooling bolt in close proximity with a portion dome of the molded article; and means for applying a flow of cooling fluid directly to the dome portion via the tip portion of the cooling bolt.

69. An apparatus for forming a molded article, which comprises: a pick-up device for removing a molded article from the mold while the article retains a quantity of heat and removing the molded article from between the mold halves of the mold; a cooling bolt which is inserted into the molded article immediately after the separation device has been removed, the molded article from between the mold halves of the mold; the cooling bolt has an internal passage that terminates in an outlet nozzle at a tip portion of the cooling bolt; the inner passage and the outlet nozzle are aligned along an axis coincident with the central axis of the molded article; the internal passage is connected to a source of cooling fluid; and the cooling bolt is positioned deep within the molded article so that the cooling fluid expelled through the outlet nozzle directly prevents the dome portion of the molded article in an amount sufficient to prevent crystallization in the dome portion.