EP1888315A2

EP1888315A2 - Coolant system for inject cores

Info

Publication number: EP1888315A2
Application number: EP06737942A
Authority: EP
Inventors: Al Brown; Sharad Shah
Original assignee: Graham Packaging Co LP
Current assignee: Graham Packaging Co LP
Priority date: 2005-05-12
Filing date: 2006-03-10
Publication date: 2008-02-20
Also published as: CN101175624A; CA2607258A1; WO2006124102A2; WO2006124102A3

Abstract

A coolant system uses a heat pipe (18) and a coolant feed pipe (10) within a coolant chamber (4) to cool an inject core (1) .

Description

COOLANT SYSTEM FOR INJECT CORES

Field of the Invention

[0001] The present invention relates to a coolant system for inject cores, which can be used as a component of a molding system. More particularly, the invention relates to using a heat pipe, a coolant feed pipe, and a coolant chamber in an inject core to cool the inject core.

Description of the Related Art

[0002] Molding systems can form a part by forcing a molding substance, such as a molten plastic, for example, a molten thermoplastic, into a mold. Concave articles can be formed by injecting the molding substance around an inject core. For example, a preform for a blow molding operation can be formed by injecting a thermoplastic, such as polyethylene terephthalate (PET), through a gate and into a cylindrical mold, an oval-shaped mold, or an elliptical-shaped mold, a cylindrical, oval-shaped, or elliptical-shaped inject core being located within the cylindrical, oval-shaped, or elliptical-shaped mold. The thermoplastic can flow out of the gate and between the inject core and the cylindrical or oval-shaped mold. After the injection step, the thermoplastic will have its highest temperature in the region near to the gate. After the thermoplastic has been injected, production of the preform can be completed by cooling the thermoplastic and opening the mold.

[0003] The properties of the molded article can depend on the rate of cooling of the substance in the mold. For example, the rate of cooling of a plastic can affect the percentage of crystallinity of the cooled molded article. The percentage of crystallinity can affect, for example, the rigidity of the molded article, hi the case of a plastic preform, the percentage of crystallinity can affect the suitability of the preform for a second step in which the preform is blown into a container. In order to minimize crystallinity, a plastic can be rapidly cooled below its glass transition point.

[0004] The rate of cooling of the molding substance, such as a molten plastic, in the mold can be controlled by cooling the mold. For example, the mold can include channels through which a cooling medium, such as water, air, or another fluid can flow. Heat can flow from the molding substance into the mold, and from the mold into the cooling medium, the cooling medium then carrying the heat to the environment. The cooling medium can be circulated through an inject core so that heat can be rapidly removed from the molding substance. The rate of heat transfer from and the temperature of the mold can be controlled by, for example, controlling the rate at which the cooling medium is circulated through the mold or inject core, or changing process variables, such as the temperature of the cooling medium or the temperature of the molding substance.

[0005] Heat pipes can be used instead of or to augment a flowing cooling medium to remove heat from a mold or an inject core. A basic heat pipe can include a solid, for example, a metal wall, with a hollow interior, the hollow interior being sealed off from the environment. The hollow interior can contain a working fluid which vaporizes at the temperature of a region from which heat is to be removed, and which condenses at the temperature of a region to which the heat is to be transferred. For example, a heat pipe can be a hollow vessel, for example, a hollow steel vessel, containing, but not completely filled with, a working fluid, for example, water. The external surface of one end of the heat pipe can contact a hot material; the working fluid vaporizes near this end. The vaporized working fluid then travels throughout the interior of the heat pipe. The external surface of another end of the heat pipe can contact a cooler material; the vaporized working fluid condenses near this end. The condensed, liquid working fluid can flow back towards the end of the heat pipe in contact with the hot material, and the cycle can repeat. The convection of the working fluid in a heat pipe can result in the heat pipe having a high overall heat transfer coefficient, without pumping or other active handling or treatment of the working fluid being required. Heat pipes can be readily incorporated in the design of an apparatus, and can be shaped and placed to remove heat from specific regions.

[0006] However, the rate of heat transferred by a heat pipe cannot be as easily controlled as the rate of heat transferred by a circulating cooling medium. Reducing the circulation rate of a cooling medium will generally reduce the rate of heat transfer, and increasing the temperature of the inflowing cooling medium will generally reduce the rate of heat transfer. In the case of a heat pipe, the rate of convection of the working fluid cannot be directly controlled; the rate of heat transfer from a hot material can be, for example, controlled by controlling the temperature of the cooler material at an end of the heat pipe opposite the hot material, or by controlling the temperature of the hot material. [0007] Previous designs for a coolant system for an inject core have included either channels for circulating cooling medium or heat pipes, but not both. Designs including channels for circulating cooling medium, but not heat pipes, have been limited in their ability to remove heat from a specific region, for example, the region of the preform in the vicinity of the gate. Designs including heat pipes, but not channels for circulating cooling medium, have been limited in their ability to actively control the rate of heat removal, and to adjust the rate of heat removal in different regions surrounding an inject core. For example, a design including a single central heat pipe cannot be adjusted to provide a higher rate of heat removal, that is, preferential heat removal, in certain regions surrounding an inject core. If a single central heat pipe is misaligned, so that the rate of heat removal is not the same in the various regions surrounding the inject core, the single heat pipe cannot be readily adjusted. [0008] There thus remains an unmet need for a cooling system which can remove heat at a high rate and in a controlled manner from an inject core to rapidly and uniformly cool a high temperature molding substance in forming a molded article, such as a preform.

SUMMARY OF THE INVENTION

[0009] It is therefore an object of the present invention to provide novel coolant systems for inject cores that allow for rapid and controllable cooling of high temperature molding substances.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure IA is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0011] Figure IB is a side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0012] Figure 2A is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0013] Figure 2B is a side sectional view of a coolant system for an inject core according to an embodiment of the invention. [0014] Figure 3 A is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0015] Figure 3B is a side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0016] Figure 4 A is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0017] Figure 4B is a side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0018] Figure 5 A is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0019] Figure 5B is a side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0020] Figure 6 A is a top sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0021] Figure 6B is a side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0022] Figure 7A is a top sectional view, with certain features shown as hidden, of a coolant system for an inject core according to an embodiment of the invention.

[0023] Figure 7B is a cutaway side sectional view of a coolant system for an inject core according to an embodiment of the invention.

[0024] Figure 8 is a perspective view of a set of baffles according to an embodiment of the invention. DETAILED DESCRIPTION

[0025] Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. A person skilled in the relevant art will recognize that other equivalent parts can be employed and other methods developed without parting from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.

[0026] An embodiment of a coolant system for an inject core can include the following, as shown in Fig. IB. The inject core 1 can be hollow, with a coolant chamber 4 in the interior. An inject core wall 2 can separate the coolant chamber 4 from the environment external to the inject core 1. The inject core 1 can have an inner bottom surface 6 and an inner circumferential surface 8, which bound the coolant chamber 4. A coolant feed pipe 10 can extend from outside of the coolant chamber 4 into the coolant chamber 4. The coolant feed pipe 10 can have a coolant feed pipe inlet 12 and a coolant feed pipe outlet 14, the coolant feed pipe outlet 14 being located within the coolant chamber 4 and the coolant feed pipe inlet 12 being located outside of the coolant chamber 4. The coolant feed pipe inlet 12 can be for fluid coupling to a cooling medium supply 28. Fluid coupling includes the direct coupling of two components so that fluid can flow between them. Fluid coupling also includes the indirect coupling of two components through a third component, so that fluid can flow between the first and second components through the third component. A heat pipe 18 has a first end 20; the first end 20 of the heat pipe 18 is located within the coolant chamber 4. The heat pipe 18 can have a second end 22. The second end 22 can be located within a heat sink channel 24. The heat sink channel 24 can be for fluidly coupling to a heat sink cooling medium supply 26. The first end 20 of the heat pipe 18 can be proximal to the inner bottom surface 6. Proximal can mean close, for example, sufficiently close for heat to flow from the inner bottom surface 6 to the heat pipe 18. The inject core 1 shown in Fig. IB is shown in a top sectional view in Fig. IA.

[0027] For example, a hot molding substance can flow from a gate located opposite of the inject core 1 and opposite of the portion of the inject core wall 2 bounding the inner bottom surface 6. Heat can be transferred from the inner bottom surface 6 and surrounding heated cooling medium to the heat pipe 18. The heat can then travel through the heat pipe 18 up to the heat sink channel 24. The second end of the heat pipe 18 can be cooled in the heat sink channel 24 by cooling medium supplied by the heat sink cooling medium supply 26. The heat pipe 18 can thus facilitate the rapid removal of heat from the hot region of the inject core wall 2, adjacent to the inner bottom surface 6. Cooling medium provided by the cooling medium supply 28 can flow through the coolant feed pipe 10 towards the inner bottom surface 6. Heat can then be transferred from the inner bottom surface 6 to the cooling medium exiting the coolant feed pipe 10. The cooling medium can then flow past the inner circumferential surface 8 and to a coolant chamber outlet 16. As the cooling medium flows, heat can transfer from the cooling medium to the heat pipe 18. Beyond the coolant chamber outlet 16, the cooling medium can be re-cooled and re-circulated to the cooling medium supply 28. The temperature of the cooling medium can be decreased and/or the rate of circulation of the cooling medium can be increased to adjust to greater demand for cooling, for example, when the molding substance is injected at a higher temperature. Further, the temperature of the cooling medium can be increased and/or the rate of circulation of the cooling medium can be decreased to adjust to a lesser demand for cooling, for example, when the molding substance is injected at a lower temperature. The cooling medium provided by the cooling medium supply 28 and flowing through the coolant chamber 4 and the cooling medium provided by the heat sink cooling medium supply 26 and used to cool the second end 22 of the heat pipe 18 can be the same. The coolant chamber outlet 16 can allow cooling medium to flow into the heat sink channel 24, and cooling medium exiting the heat sink channel 24 can be re-cooled and re-circulated to the heat sink cooling medium supply 26 and to the cooling medium supply 28.

[0028] The coolant feed pipe 10 can be aligned with its longitudinal axis approximately collinear with a longitudinal axis of the inject core 1. The coolant feed pipe outlet 14 can be located near to the inner bottom surface 6 so that the cooling medium exits with a high velocity. The flow rate of the cooling medium can be set so that the flow of the cooling medium exiting the coolant feed pipe outlet 14 is turbulent.

[0029] The heat pipe 18 can be proximal to the coolant feed pipe 10, as shown in the cross-section taken perpendicular to the longitudinal axis of the inject core 1 of Fig. 2A and in the cross-section taken to include the longitudinal axis of the inject core 1 of Fig. 2B. Proximal can mean that the heat pipe 18 is close to the coolant feed pipe 10, for example, sufficiently close for heat to flow between the coolant feed pipe 10 and the heat pipe 18. Having the heat pipe 18 proximal to the coolant feed pipe 10 can allow, for example, for the heat pipe 18 also to be cooled at an intermediate part of its length rather than only at its second end 22. When the heat pipe 18 is proximal to a coolant feed pipe 10 located such that the longitudinal axis of the coolant feed pipe 10 is approximately collinear with a longitudinal axis of the inject core 1, the heat pipe 18 can rapidly transfer heat from the molding substance in the region of the preform in the vicinity of the gate. When the heat pipe 18 is proximal to the coolant feed pipe 10, the heat pipe 18 can disrupt the flow of cooling medium emerging from the coolant feed pipe outlet 14 so as to modify the flow into a form which better transfers heat, for example, better transfers heat from the inner bottom surface 6 of the inject core 1, than an unmodified flow of cooling medium emerging from the coolant feed pipe outlet 14.

[0030] The heat pipe 18 can be proximal to the inner circumferential surface 8, as shown in the cross-section taken perpendicular to the longitudinal axis of the inject core 1 of Fig. 3 A and in the cross-section taken to include the longitudinal axis of the inject core 1 of Fig. 3B. Proximal can mean that the heat pipe 18 is close to the inner circumferential surface 8, for example, sufficiently close for heat to flow from the inner circumferential surface 8 to the heat pipe 18. For example, the heat pipes 18 can be distributed on the inner circumferential surface 8 to preferentially remove heat from certain regions of the inject core wall 2. For example, an inject core 1 can be elliptical in a cross-section perpendicular to its longitudinal axis. It can be important to rapidly remove heat from the part of the inject core wall 2 at the extrema of the major axis of the elliptical cross-section. To achieve rapid cooling at these extrema, heat pipes 18 can be clustered adjacent to the inject core wall 2, near to these extrema.

[0031] The heat pipe 18 can also be proximal to both the coolant feed pipe 10 and the inner circumferential surface 8. For example, the heat pipe 18 and/or the coolant feed pipe 10 can be sufficiently large in diameter so that the heat pipe 18 simultaneously touches the coolant feed pipe 10 and the inner circumferential surface 8. The coolant system can include one coolant feed pipe 10 or multiple coolant feed pipes 10, and can include one heat pipe 18 or multiple heat pipes 18.

[0032] The heat pipe 18 can be proximal to the coolant feed pipe 10. The heat pipe

18 can have the form of an annular cylinder. That is, the heat pipe 18 can have the form of an elongated hollow ring, with fluid being able to freely pass through the center of the ring.

For example, the coolant feed pipe 10 can be located in the coolant chamber 4 near to the longitudinal axis of the inject core 1, and the annular cylinder heat pipe 18 can surround the coolant feed pipe 10. The annular cylinder heat pipe 18 can be proximal to the inner circumferential surface 8, as shown in Figs. 4A and 4B.

[0033] The coolant feed pipe 10 can be proximal to the inner circumferential surface

8. Proximal can mean that the coolant feed pipe 10 is close to the inner circumferential surface 8, for example, sufficiently close for heat to flow from the inner circumferential surface 8 to the coolant feed pipe 10.

[0034] The coolant feed pipe 10 can be proximal to the heat pipe 18. The coolant feed pipe 10 can have the form of an annular cylinder. That is, the coolant feed pipe 10 can have the form of an elongated hollow ring, with fluid being able to freely pass through the center of the ring. For example, the heat pipe 18 can be located in the coolant chamber 4 near to the longitudinal axis of the inject core 1, and the annular cylinder coolant feed pipe 10 can surround the heat pipe 18. The annular cylinder coolant feed pipe 10 can be proximal to the inner circumferential surface 8, as shown in Figs. 5 A and 5B.

[0035] The coolant system can also include a coolant feed pipe valve. The coolant feed pipe inlet 12 can be fluidly coupled to the coolant feed pipe valve. The coolant feed pipe valve can be for fluidly coupling to the cooling medium supply 28. That is, the cooling medium supply 28 can provide cooling medium to the coolant feed pipe valve, and the coolant feed pipe valve, if open, can provide cooling medium to the coolant feed pipe inlet 12. The coolant system can include multiple coolant feed pipes 10 and multiple coolant feed pipe valves. Multiple coolant feed pipe inlets 12 can be fluidly coupled to a single coolant feed pipe valve. For example, several coolant feed pipe inlets 12 can be fluidly coupled to a first coolant feed pipe valve, several other coolant feed pipe inlets 12 can be fluidly coupled to a second coolant feed pipe valve, and so forth. By adjusting the openings of the valves relative to each other, a greater flow rate of cooling medium can be supplied to some coolant feed pipes 10 than to other coolant feed pipes 10. In this manner, preferential cooling can be achieved in certain regions of the coolant chamber 4 or in certain regions along the inject core wall 2.

[0036] For example, multiple coolant feed pipes 10 can be located proximal to the inner circumferential surface 8 of an inject core 1 having an elliptical cross-section perpendicular to the longitudinal axis of the inject core 1. The coolant feed pipe valves fluidly coupled to coolant feed pipes 10 positioned near to the extrema of the major axis of the elliptical cross-section can be adjusted so that the flow rate of cooling medium through these coolant feed pipes 10 is greater than the flow rate of cooling medium through coolant feed pipes 10 located near to the extrema of the minor axis of the elliptical cross-section. Thus, the region of the inject core wall 2 near to the extrema of the major axis of the elliptical cross-section can be preferentially cooled. Furthermore, the coolant feed pipe valves can be adjusted from one injection molding operation to the next or even during a single injection molding operation. For example, over the course of many injection molding operations an inject core 1 may become misaligned, so that the path for the flow of a molding substance along one side of the inject core 1 is narrower than the path along the opposite side of the inject core 1. It can be that the difference in the thickness of regions on two sides of the resultant molded container or preform is not in itself a problem. However, the fact that the thinner region cools much faster than the thicker region can lead to a difference in material properties of the two portions of the wall which is unacceptable. Rather than disassembling the molding apparatus to re-align the inject core 1, which can be an expensive and time- consuming procedure requiring shutdown of the molding apparatus, the coolant feed pipe valves can be adjusted. The valves can be adjusted so that the flow rate of cooling medium to coolant feed pipes 10 near to the region of the narrower path for the molding substance is less than the flow rate of cooling medium to the coolant feed pipes 10 near to the region of the wider path for the flow of molding substance. Thus, the coolant feed pipe valves can be adjusted to preserve an even rate of cooling of the molding substance, despite misalignment of the inject core 1.

[0037] In an embodiment, illustrated in Figs. 6A and 6B₃ substantially all of the inner circumferential surface 8 corresponding to a longitudinal extent of the coolant feed pipes 10 is proximal to the coolant feed pipes 10. For example, over the region of the inner circumferential surface 8 where the coolant feed pipes 10 project downwards toward, but do not touch, the inner bottom surface 6, substantially all of the inner circumferential surface 8 can be in contact with the coolant feed pipes 10. The coolant feed pipes 10 can be, for example, oval-shaped, kidney-shaped, or have the form of a segment of a circle in cross- section to conform to the inner circumferential surface 8, as shown in Figure 6 A. Each coolant feed pipe 10 can be connected to a different coolant feed pipe valve. The coolant feed pipe valves can be independently adjusted to control the rate of heat removal from, and therefore the temperature of each sector of the inject core wall 2 adjacent to a coolant feed pipe 10. Thus, embodiments of the coolant system presented herein not only allow for control of the overall rate of heat removal by adjusting the volumetric rate of cooling medium flow and the temperature of cooling medium provided by the cooling medium supply 28, but also allow for the rate of heat removal to be independently adjusted for different regions of the inject core wall 2 by adjusting coolant feed pipe valves. [0038] The heat pipe 18 and the coolant feed pipe 10 can have any one of a number of shapes. For example, the heat pipe 18 or coolant feed pipe 10 can be circular, elliptical, square, triangular, polygonal, or have any other shape in a cross-section perpendicular to its longitudinal axis. Furthermore, the heat pipe 18 or coolant feed pipe 10 can be of uniform and constant cross-section along its longitudinal axis, can be tapered along its longitudinal axis, can undulate along its longitudinal axis, or can have various different cross-sectional forms along its longitudinal axis.

[0039] The coolant system can include a set of baffles 72 in the coolant chamber 4 which directs the flow of cooling medium in the coolant chamber 4, as illustrated in Figs. 7 A and 7B. The set of baffles 72 can include one or more plates 74; for example, the set of baffles 72 illustrated in Figs. 7A and 7B has two plates, 74a and 74b. The plates 74 can direct the flow of cooling medium to increase the rate of heat transfer between the inject core wall 2 and the cooling medium and between the inject core wall 2 and the heat pipe 18. The rate of heat transfer can be expressed in, for example, joules per second transferred from the inject core wall 2 to the cooling medium, or joules per second transferred from the inject core wall 2 to the heat pipe 18. The plates 74 can prevent cooling medium which has exited the coolant feed pipe outlet 14 from immediately flowing upwards near the longitudinal axis of the inject core 1 without approaching and receiving heat from the inner circumferential surface 8. For example, the plates 74 can increase the mean path length of a fluid particle between the coolant feed pipe outlet 14 and the coolant chamber outlet 16. For example, the plates 74 can direct the cooling medium to flow circumferentially in planes perpendicular to the longitudinal axis of the inject core 1, as shown in Figs. 7A and 7B. [0040] In a set of baffles 72 with two or more plates 74, the plate nearest to the inner bottom surface 6 can be termed the first end plate 74b, and the plate farthest from the inner bottom surface 6 can be termed the second end plate 74a. A pair of plates, for example, the first end plate 74b and the second end plate 74a shown in Figs. 7A and 7B, can be separated by, be in contact with, and/or be connected by a baffle wall 76. Figure 7A shows a top view of a second end plate 74a and shows features below the second end plate 74a in dashed lines. For example, an outside through hole 78a in the second end plate 74a is shown as a solid semicircle adjacent to the inject core wall 2 in the lower portion of Fig. 7 A. An outside through hole 78b in the lower plate 74b is shown as a dashed semicircle adjacent to the inject core wall 2 in the left portion of Fig. 7A. The outside through holes 78a and 78b can be located at the periphery of the plates 74a and 74b, as shown in Fig. 7A, or the outside through holes 78a and 78b can be located in another portion of the plates 74a and 74b. A coolant feed pipe 10 can extend through center through holes in the second end plate 74a and the first end plate 74b. Heat pipes 18 can extend through intermediate holes in the second erid plate 74a and first end plate 74b. Alternatively, a heat pipe 18 can extend through center through holes and coolant feed pipes 10 can extend through intermediate holes. A baffle wall 76, separating and in contact with the second end plate 74a and the first end plate 74b is shown by two dashed lines extending from the coolant feed pipe 10 in the center to the inject core wall 2 in the lower left portion of Fig. 7A. Cooling medium can flow out of the coolant feed pipe outlet 14, past the inner bottom surface 6 and up through the outside through hole 78b in the first end plate 74b, as illustrated in Fig. 7B. Cooling medium is blocked from flowing in a counterclockwise direction by the baffle wall 76, but can flow in a clockwise direction, as shown by the arrow of semicircular shape in Fig. 7A. The cooling medium can then travel up through the outside through hole 78a in the second end plate 74a and continue traveling upward in the coolant chamber 4.

[0041] The plates 74 can be proximal to the inner circumferential surface 8.

Proximal can be mean that a plate 74 is close to the inner circumferential surface 8, for example, sufficiently close for heat to flow from the inner circumferential surface 8 to the plate 74, and/or sufficiently close so that cooling medium must flow through an outside through hole 78 and cannot flow between a gap between the plate 74 and the inner circumferential surface 8.

[0042] The set of baffles 72 can consist of more than two plates 74, with each plate having one or more outside through holes 78 and each pair of plates being separated by, being in contact with, and/or being connected by one or more baffle walls 76. The baffle

walls 76 can be located at a different angular position θ in a plane perpendicular to the longitudinal axis of the inject core 1 for each successive pair of plates. Such staggering of the baffle walls 76 can ensure that any zones in which cooling medium moves at a slow velocity are not all located along a single strip at a single angular position extending in the longitudinal direction of the inject core 1 adjacent to the inject core wall 2. [0043] The plates 74 can be oriented so that the normal of each plate 74 is approximately parallel to a longitudinal axis of the inject core 1. Alternatively, the plates 74 can be oriented with their normals at angles which are not parallel to the longitudinal axis of the inject core 1; or some plates 74 can be oriented with their normals at angles approximately parallel to the longitudinal axis, and other plates 74 can be oriented with their normals at angles not parallel to the longitudinal axis of the inject core 1. [0044] When a molding substance is injected and flows past the inject core 1, the inject core 1 can be subjected to very large pressure differentials. If the pressure imposed on one side of the inject core 1 is different from the pressure imposed on an opposite side of the inject core 1, the inject core 1 can be subjected to a force which tends to bend it away from the center of a mold. In addition to directing the flow of cooling medium, the set of baffles 72 can act to mechanically reinforce the inject core 1 against such bending forces or other externally imposed forces which can otherwise tend to distort the inject core 1. The mechanical reinforcement provided by a set of baffles 72 can allow the inject core 1 to be designed with a thinner inject core wall 2, with the resultant advantage of allowing less material to be used so that the inject core wall 2 can be lighter and cheaper, and with the resultant advantage that the heat transfer coefficient for heat flowing through the inject core wall 2 can be greater. Alternatively, the thickness of the inject core wall 2 can be maintained constant but the inject core 1 can be subject to larger pressure differentials. [0045] In an embodiment, a set of baffles 72 has two or more plates 74, each plate has at least one outside through hole 78, and each plate 74 is connected to another plate 74 by at least one baffle wall 76. The plates 74 can be circular or elliptical in shape, or have any other shape. Because the plates 74 can be connected to each other by one or more baffle walls 76, the set of baffles 72 can be a single rigid device. A set of baffles 72 is shown in perspective view in Fig. 8. The set of baffles 72 can have a first end plate 74b and a second end plate 74a. When the set of baffles 72 is placed within a container, such as an inject core 1, each plate 74 can be proximal to a wall of the container, for example, proximal to an inner circumferential surface 8 of an inject core wall 2. Proximal can be mean that each plate 74 is close to a wall of the container, for example, sufficiently close for heat to flow from the wall of the container to the plate 74, and/or sufficiently close so that cooling medium must flow through the outside through holes 78 and cannot flow between a gap between the plate 74 and a wall of the container. However, the plate 74 need not be permanently connected to a wall of the container. For example, a slip fit can be formed between the plate 74 and a wall of the container; the set of baffles 72 can then be removed from the container, for example, for cleaning. The container can be, for example, an inject core 1, and the wall of the container can be an inject core wall 2 with an inner circumferential surface 8. When the set of baffles 72 is placed within a container, such as an inject core 1, a continuous channel for the flow of a fluid, such as cooling medium, through the set of baffles 72 can be formed. For example, fluid can flow from the side of the first end plate 74b opposite other plates, through an outside through hole 78d in the first end plate 74b, successively through outside through holes 78 in other plates 74, and finally through an outside through hole 78c in the second end plate 74a to the side of the second end plate 74a opposite other plates 74. [0046] A plate 74 can have a center through hole. A center through hole can receive a pipe. For example, a pipe, such as a coolant feed pipe 10 or a heat pipe 18, can fit through the center through hole. When a pipe is inserted through the center through hole, the pipe can be proximal to the plate 74. Proximal can mean that the pipe is close to the plate 74, for example, sufficiently close for heat to flow between the pipe and the plate 74, and/or sufficiently close so that cooling medium cannot flow between a gap between the pipe and the plate 74. However, the plate 74 need not be permanently connected to the pipe. For example, a slip fit can be formed between the pipe and the center through hole of the plate 74.

[0047] The set of baffles 72 can have an inner column 80. The inner column 80 can be hollow, having a center through hole in its center, so that a pipe, for example, a coolant feed pipe 10 or a heat pipe 18, can fit through the center through hole.

[0048] One or more plates 74 can be formed of a high heat conductivity alloy. For example, the first end plate 74b and/or the second end plate 74a can be formed of a high heat conductivity alloy. For example, when the set of baffles 72 is placed within an inject core 1, it can be advantageous for the end plate located nearest to the inner bottom surface 6 to be formed of a high heat conductivity alloy, because when the gate of an injection molding device is opposite of the portion of the inject core wall 2 bounding the inner bottom surface 6, this end plate can be the hottest of the plates 74. It can also be advantageous to, for example, have one or more of the plates 74 near to this end plate formed of a high heat conductivity alloy. All of the plates 74 can be formed of a high heat conductivity alloy. An example of a high heat conductivity alloy is a copper alloy, such as Moldstar 90. For example, Fig. 8 illustrates a first end plate 74b formed of a high heat conductivity alloy bonded to another plate 74 not formed of a high heat conductivity alloy; a bond line 82 is shown. [0049] A method for cooling an inject core 1 includes forcing a cooling medium to a bottom region of a coolant chamber 4. This bottom region can be bounded by an inner bottom surface 6 of the inject core 1. The cooling medium can be allowed to flow through the coolant chamber 4 and exit the coolant chamber 4 through a coolant chamber outlet 16. Heat can be transported away from the inner bottom surface 6 of the inject core 1 with a heat pipe 18. The cooling medium can be, for example, water, a hydrocarbon oil, a silicone oil, air, or any fluid suitable for the conditions of a molding process.

[0050] A heat sink cooling medium can be forced through a heat sink channel 24.

The heat sink cooling medium can, for example, absorb heat transported away from the inner bottom surface 6 of the inject core 1 with the heat pipe 18. The heat sink cooling medium can be, for example, water, a hydrocarbon oil, a silicone oil, air, or any fluid suitable for the conditions of a molding process. The cooling medium exiting the coolant chamber 4 through the coolant chamber outlet 16 can flow into the heat sink channel 24. The cooling medium flowing through the coolant chamber 4 and the heat sink cooling medium can be the same fluid. Use of the same fluid for the cooling medium flowing through the coolant chamber 4 and the heat sink cooling medium can simplify the design of the coolant system. [0051] Cooling medium can be forced to the bottom region of the inject core 1, for example, through a coolant feed pipe 10, at a volumetric rate sufficient for the flow of cooling medium exiting the coolant feed pipe 10, for example, at a coolant feed pipe outlet 14, to be turbulent. [0052] The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above- described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.

Claims

WHAT IS CLAIMED IS:

1. A coolant system for an inject core, comprising: a heat pipe; a coolant chamber within the inject core; a coolant feed pipe having a coolant feed pipe inlet for fluidly coupling to a cooling medium supply and having a coolant feed pipe outlet located within the coolant chamber; the inject core having an inner bottom surface and an inner circumferential surface; the heat pipe having a first end located within the coolant chamber.

2. The system of claim 1, further comprising a heat sink channel for fluidly coupling to a heat sink cooling medium supply, wherein the heat pipe has a second end located within the heat sink channel.

3. The system of claim 1 , wherein the first end of the heat pipe is proximal to the inner bottom surface.

4. The system of claim 1, wherein a longitudinal axis of the coolant feed pipe is approximately collinear with a longitudinal axis of the inject core.

5. The system of claim 1, wherein the heat pipe is proximal to the coolant feed pipe.

6. The system of claim 1, wherein the heat pipe is proximal to the inner circumferential surface.

7. The system of claim 1, the heat pipe having the form of an annular cylinder.

8. The system of claim 1, the coolant feed pipe having the form of an annular cylinder.

9. The system of claim 1, wherein the coolant feed pipe is proximal to the inner circumferential surface.

10. The system of claim 1 , further comprising a coolant feed pipe valve, wherein the coolant feed pipe inlet is fluidly coupled to the coolant feed pipe valve, and wherein the coolant feed pipe valve is for fluidly coupling to the cooling medium supply.

11. The system of claim 1 , further comprising a plurality of coolant feed pipe valves and a plurality of coolant feed pipes, wherein each coolant feed pipe inlet is fluidly coupled to one coolant feed pipe valve, and wherein the coolant feed pipe valves are for fluidly coupling to the cooling medium supply.

12. The system of claim 1, wherein substantially all of the inner circumferential surface corresponding to a longitudinal extent of the coolant feed pipes is proximal to the coolant feed pipes.

13. The system of claim 1, further comprising a set of baffles in the coolant chamber for directing the flow of cooling medium to increase the rate of heat transfer between the inject core wall and the cooling medium and between the inject core wall and the heat pipe.

14. The system of claim 13 , wherein the set of baffles comprises at least two plates, wherein a pair of plates are separated by and in contact with at least one baffle wall, and wherein the at least two plates are proximal to the inner circumferential surface.

15. The system of claim 13 , wherein the set of baffles comprises at least one plate and wherein the at least one plate has at least one outside through hole.

16. The system of claim 13, wherein the set of baffles comprises at least one plate, wherein each plate has a center through hole, and wherein a pipe selected from the group consisting of a heat pipe and a coolant feed pipe is inserted through the center through hole.

17. A set of baffles, comprising: a plurality of plates; wherein each plate has at least one outside through hole; the plurality of plates comprising a first end plate and a second end plate; and wherein each plate is connected to another plate by at least one baffle wall, wherein when the set of baffles is placed within a container, each plate is proximal to a wall of the container and wherein a continuous channel through which a fluid can flow from a side of the first end plate opposite other plates, through the at least one outside through hole, to a side of the second end plate opposite other plates is present.

18. The set of baffles of claim 17 , wherein at least one plate has a center through hole and wherein the center through hole is capable of receiving a pipe.

19. The set of baffles of claim 17, wherein at least one of the first end plate and the second end plate is comprised of a high heat conductivity alloy.

20. A method for cooling an inject core, comprising: forcing a cooling medium to a bottom region of a coolant chamber bounded by an inner bottom surface of the inject core; allowing the cooling medium to exit the coolant chamber through a coolant chamber outlet; and transporting heat away from the inner bottom surface of the inject core with a heat pipe.

21. The method of claim 20, further comprising: forcing a heat sink cooling medium through a heat sink channel, wherein the heat sink cooling medium is capable of absorbing heat transported away from the inner bottom surface of the inject core with the heat pipe.

22. The method of claim 20, wherein the cooling medium is forced to the bottom region of the coolant chamber at a sufficient volumetric rate for the flow of cooling medium exiting a coolant feed pipe to be turbulent.