CA2271099A1 - Heatpipe mold - Google Patents

Abstract

Method of making a mold half part and the mold part apparatus as so made, wherein a molding surface structure is formed having a first molding surface and a second surface remote from the first surface and defining therebetween a generally constant cross-sectional thickness. A heatpipe chamber is operably coupled to the mold surface structure for phase change heat transfer to or from the first surface via the structure and second surface. The heatpipe chamber means encompasses substantially all of the area of the first molding surface projected in a direction perpendicular to the parting line of the half mold part and in a preferred embodiment is in the form of cup-like or box-like shell having side walls joined to a bottom wall and having an open top closed by the molding surface structure so as to define a single chamber at least generally co-extensive and subjacent to the molding structure first surface. This chamber is sealed, evacuated and lined with wick material and charged with a suitable fluid to thereby be operable as a heatpipe. Cooling coils or heating elements are arranged in heat transfer relation with the shell walls. A plurality of support pillars in the heatpipe chamber support the first surface against deformation when the same is subjected to molding pressures in the operation of the mold part in a mold cycle. The pillars can be hollow sintered inert metal columns filled or lined with a supplementary wicking material or hollow metal perforated tubes.
The perforated support tubes also act as a dispersing nozzle or nozzles for the incoming liquid phase charge fluid entering the chamber from a supplemental charge fluid pumping system, or they may act as charge fluid liquid phase evacuation outlets from the heatpipe chamber to the supplementary pumping system. In an alternate embodiment a side-by-side nest of a plurality of pre-made heatpipe elements form an array having lateral dimensions at least generally co-extensive with the lateral dimensions of the first surface of the half mold part when finished. The array of heatpipe elements are encapsulated with a mold-forming material having the mold-cavity-defining first surface.

Description

HEATPIPE MOLD
This is a regular United States patent application filed pursuant to 35 USC ~

(a) and claims the benefit under the provisions of 35 USC ~ 119 (e) (1) of the priority of United States provisional patent application SN 60/064,066 filed October 17, 1997.
S Field of the Invention This invention relates to molding apparatus and methods, more particularly to method and apparatus for cooling and/or heating the mold-cavity-defining surfaces of a mold.
Background of the Invention l0 The technology associated with the production of electroformed inserts for molds is well known. See, for example, U. S. patent 4, 338, 968. This electroform processing technology is described hereinafter in order to highlight the difficulty associated with heating or cooling the electroform while it is in place in a mold.
As diagrammatically illustrated in Fig. l, electroformed mold inserts are usually 15 produced by depositing nickel or some other elemental metal onto a machined pattern form 20 through an electroplating process. i he pattern form 20 has been machine shaped to satisfy the geometry that is the reverse (mirror) of a desired molding surface. The electroplating process is stopped when the nickel deposit 22 on the machined form has achieved sufficient thickness. The nickel deposit 22 is then removed from the pattern 20 form 20. The surface 24 of the deposited nickel that has been in contact with the machined form 20 has now assumed the shape, thickness and dimension of the machined mating surface 26 of form 20 such that it can now be used as a molding surface, as diagrammatically indicated in Fig. 2, Due to the nature of the deposition process, this electroform 22 has a generally constant cross sectional thickness.
As shown diagrammatically in Fig. 3, and as taught conventionally in the prior art, electroform 22 is typically bedded on and welded at 28 to a metal (or otherwise affixed to a non-metal) backing or bedding block 30 to enable the electroform to operate in the high pressure environment of the molding process. Bedding block 30 is either cooled or heated to provide the correct temperature to the electroformed molding face 24 during the molding process. As best seen in Fig. 3A, due to the random as-manufactured tolerance variance irregularities in spacing between the electroformed non-molding surface 32 and the electroform mounting surface 34 of the bedding block, significant air gaps 36 occur.
These air gaps create random thermal breaks between surfaces 32 and 34 which act as insulators that restrict the transfer of heat energy between the electroform 22 and the bedding block 30 and therefore cause electroform 22 to be heated or cooled in an inappropriately slow and non-uniform fashion.
As shown diagrammatically in Fig. 4, heatpipe technology is also well known and consists of introducing a charge fluid liquid phase 40 into an evacuated chamber 42 having inert elemental metal, chamber-defining, interior boundary surfaces (not shown) lined with a wick structure 42 to transport the liquid phase of the charge fluid. The atmospheric pressure within the evacuated chamber 42 is made low enough to permit phase change of the charge fluid when very small temperature changes occur at any random evaporation locations 44 and 46 on the interior surface of chamber 42.
This localized increase in temperature causes the charge fluid at sites 44 and 46 to change state from liquid 40 to vapor 50 due to the low vapor pressure in the chamber. This phase change causes the vapor to absorb the energy associated with the latent heat of evaporation of the liquid phase of the fluid. The phase change in turn produces a localized positive pressure which causes the vapor to migrate, as indicated by arrows 48, within chamber 42 to a lower pressure area. As the vapor 50 contacts a condensation location 52, 54 that is marginally lower in temperature than the vapor, the vapor changes phase back to a liquid and all the latent heat of condensation residing in the vapor is yielded to the chamber wall at that condensing site. Wick structure 42 installed along the boundary surface in the chamber assists, by capillary action, return of the liquid to the evaporation site 44, 46 to assure that fluid is available to continue the phase change reaction. In this way, large amounts of thermal energy can be transferred uniformly at a high rate throughout the chamber.
Qbiects of the Invention Accordingly, among the objects of the present invention are to provide a new and improved method and apparatus for utilizing the nickel electroplated deposit that forms the thin mold face piece or equivalent mold surface structure normally used to define the cavity-side surface of the mold in an improved heatpipe mold construction and method that insures uniform heating andlor cooling of the mold-cavity-side surface of the molding surface during the molding cycle, and which eliminates the aforementioned randomized thermal breaks so that the heating and cooling can occur rapidly and in a uniform fashion.
Summary of The Invention In general, and by way of summary description and not by way of limitation, the invention achieves the foregoing as well as other objects indicated hereinafter by providing a heatpipe construction arranged, constructed and configured to function as a mold half with the entire electroformed mold piece serving as one end of the mold heatpipe chamber.
Brief Description of the Drawings The foregoing, as well as other objects, features and advantages of the present invention will become apparent from the fohowing detailed description of the best mode presently known by the inventor for making and using the invention, from the appended claims and from the accompanying drawings wherein:
Fig. 1 is a diagrammatic illustration of making a mold-cavity-defining-surface piece made by electroplating nickel onto the cavity-forming complemental surface of a machined pattern form in accordance with conventional prior art practice.
Fig. 2 is a diagrammatic illustration of the electroform part after completion thereof and removal from the machined pattern form, and inverted for assembly to a lower mold half bedding block in accordance with prior art practice.

Fig. 3 is a diagrammatic view of the electroform superimposed on, and fastened by peripheral edge welding to, a mold bedding block so as to be supported by the electroform mounting surface of the bedding block and therefore provide a sub-assembly to be used as a lower mold half of a typical two-piece openable and closable mold assembly.
Fig. 3A is a fragmentary view of the portion encircled by the circle 3A in Fig. 3 and greatly enlarged thereover.
Fig. 4 is a diagrammatic illustration of the structure and made of operation of a typical heatpipe of the prior art.
Fig. 5 is a diagrammatic view of a lower mold half part defining a negative or cavity molding face surface and constructed as a heatpipe mold in accordance with the invention.
Fig. SA is a diagrammatic view illustrating the lower mold half of Fig. 5 in operative juxtaposition to another, upper mold half part defining a positive or core molding face surface and likewise constructed in accordance with the invention as a heatpipe mold.
Fig. 6 is a diagrammatic view illustrating a second embodiment of the mold half part of Fig. 4 modified by being equipped with associated exterior cooling tubes to thereby adapt the same for use in a thermoplastic molding application in which the molding surface is to be cooled to cause solidification of the molding material before removal from the mold.
S

Fig. 7 is a view similar to Fig. 6 illustrating a third embodiment of the mold half of Fig. 4 modified by associated exterior heating elements being provided to adapt the mold half for use in molding of thermosetting plastic material that must be heat cured within the mold to cause solidification before the mold can be opened.
Fig. 8 is a diagrammatic view of a fourth embodiment modification of the third embodiment of Fig. 6 in which the cooling tubes are replaced with coolant passages in a thicker section shell wall of the heatpipe lower mold half.
Fig. 9 is a diagrammatic view of fifth embodiment of a mold half of the type shown in Fig. 5 in which a series of inert metal support pillars are installed in the mold heatpipe chamber to transmit molding pressure applied to the mold cavity surface through the chamber to the mold frame.
Fig. 9A is a sixth embodiment of the mold half similar to that of Fig. 9, but wherein the support pillars are constructed of hollow or solid sintered materials.
Fig. 9B is seventh embodiment of a mold half similar to that of the embodiments of Figs. 9 and 9A in which the support pillars are constructed as perforated tubes.
Fig. 9C is a greatly enlarged fragmentary view of the portion encompassed by the ellipse 9C in Fig. 9B.
Fig. 10 is a diagrammatic view of an eighth embodiment of the mold half similar to the embodiment of Fig. 6 but in which the charge fluid is augmented by an external pumping circuit for use in instances where the molding operational thermal demands exceed the ability of the interior wick to replace the charge fluid at the evaporator site or sites.

Fig. l0A is a diagrammatic view of a ninth embodiment of the mold half part combining the external pumping circuit of the eighth embodiment of Fig. 10 with the perforated support pillars of the sixth and seventh embodiments of Figs. 9B
and 9C in which the pillars act as dispersion nozzles for the external pumping circuit.
Fig. lOB is a tenth embodiment of the mold half similar to the embodiment of Figs. 9B and 9C but wherein the perforated support pillars act as evacuation outlets for outgoing charge or working fluid circulation into external pumping circuit (not shown).
Fig. 11 is a diagrammatic view of an eleventh embodiment similar to the view of Fig. 5 but wherein the mold-cavity-defining end cap of the heatpipe is machined from a suitable heat conductive metallic material and its chamber-facing surface plated with an elemental metal to prevent contamination of the charge fluid in the heatpipe chamber.
Fig. 1 lA is a greatly enlarged fragmentary view of the portion encompassed by the circle 11A in Fig. 11.
Fig. 12 is a diagrammatic view of a twelfth embodiment of the invention utilizing the two mold halves of Fig. SA, the heating or cooling tubes of Figs. 6 or 7 and incorporating the same into. complemental mold nests in upper and lower platens of a compression mold assembly for use in compression molding of plastic material.
Fig. 13 is a diagrammatic view of a thirteenth embodiment of the invention wherein pre-formed individual heatpipes are nested and incorporated integrally with electroform encapsulating material that defines the end cap of the massed heatpipe mold part during the plating process.

Fig. 13A is a fourteenth embodiment of the invention similar to the embodiment of Fig. 13, but illustrating the massed array of nested heatpipes extending beyond the bottom face of the electroform body.
Detailed Description of the Preferred Embodiments of the Invention In accordance with the present invention, and referring to Fig. 5, a significant improvement in the energy transfer rate and surface temperature uniformity of the electroformed molding surface 24 can be achieved if the electroform 22 is attached by a circumferentially continuous weld 52 to the upper edge of a mold half shell 60 made of electroformed nickel and constructed and arranged in a three-dimensional configuration, e.g., a five-sided box open at the top, and then capped by electroform 22, thereby creating a sealed chamber 64. A wick material 66 is installed in the chamber as an interior capillary transport covering over preferably all interior facing surfaces that define chamber 64. The chamber is then evacuated, after which charge fluid 40/50 is injected into the chamber. The chamber therefore has all the components associated with a heatpipe and is operable to function as a unitary heatpipe. This heatpipe assembly then can be utilized as a lower mold half 70 providing the negative or cavity molding surface 24 when used in conjunction with a suitable mating upper mold half 72, as shown diagrammatically in Fig. SA. Mold half 72 is constructed in the manner of mold half 70 but with its electroform end cap 74 configured as the inverse of the end cap electroform 22 of mold half 70 to thereby provide for example, a positive or core molding surface 76 complemental to surface 24.

Fig. 6 illustrates a second embodiment of the invention wherein the electroform/shell heatpipe mold assembly is constructed for use in a thermoplastic molding application. In such applications the molding material is applied to the molding surface 24 in a heated condition and must be cooled to cause solidification before removal from the mold. Hence, thermal energy from the molding material being formed by the lower and upper molding surfaces 24 and 76 of the mold cavity is at a positive temperature with respect to these molding surfaces. This energy is rapidly conducted through such electroform to the associated shell surface via the evaporation and condensation occurring within the associated chamber. Each shell can then be cooled through the use of fins (not shown) or cooling tubes 80 bonded to, or integral with, the shell exterior surfaces.
It is to be noted that, in accordance with one of the principal features of the invention, these exterior shell surfaces can be many times larger in exposed heat transfer area than the electroformed molding surface 22/76. Therefore, the heat energy applied to or removed from the electroform surfaces 24, 76 will be transferred thereto or dissipated therefrom at rates that are a function of the ratio of the surface areas of each electroform and the associated shell. Thus, an electroform having a mold-cavity-defining surface area, for example, of 4 square inches that is welded as a heatpipe end cap to a heatpipe shell having an exposed exterior surface area of 20 square inches, and then the mold heatpipe chamber sealed, evacuated and fluid charged to function as a heatpipe mold, will transfer energy to or from the electrofolm surface at a rate approximately five times faster than an electroform bearing directly on a conventional bedding block 30, provided that the shell and the bedding block are heated or cooled at the same rate per unit time.
Fig. 7 illustrates a third embodiment application involving the molding of thermosetting plastic wherein the molding material is presented to the molding surfaces in a relatively cool form and must be heat cured within the mold cavity to cause solidification before the mold can be opened. The molding material, being formed by the molding surfaces, in such application is at a negative or lower temperature with respect to the molding surfaces. In this instance it would be necessary to provide thermal energy to the molding surfaces in order to cure the molding material. Accordingly, in this embodiment a suitable form of energy is supplied to an array of heating elements 82 bonded to or otherwise mounted in the shell wall or on the exterior shell surface. The heat thus generated by heating elements 82 is then transferred to the molding surface 24 through evaporation and condensation of the charge fluid 40/50 occurring within the evacuated chamber 64. The wick 66 returns condensate to the evaporator site as in the first instance above. The same thermodynamic reaction takes place as in the cooling instance, but the evaporator and condenser surfaces are reversed.
In both of the above applications the cooling or heating introduced to the shell can be in the form of heaters or cooling tubes bonded to the shell exterior surfaces.
Alternatively, as diagrammatically illustrated in the fourth embodiment of Fig. 8, if the walls of shell 60 are of sufficient thickness, the cooling tubes 80 can be replaced with coolant passages 84 in these shell walls, or in the case of heating elements, holes can be drilled in the shell walls to accommodate the heaters.

From the foregoing it now will be seen that, pursuant to another principal feature of the invention, in either the cooling or heating applications the electroform, shell, wick structure, and charge fluid form one integral heatpipe half mold unit that can be installed in a mold frame or fixture and removed therefrom, simply, without disassembly of the unit or constituent chamber components.
Fig. 9 illustrates a fifth embodiment modification that is preferred in those instances where the electroform heatpipe end cap structure, due to the molding pressures and the geometry of the molding surface, is insufficient to support typically applied molding pressures. In such instances, a series of inert metal pillars 86 and 88 are l0 installed in chamber 64 of modified mold half 87 to support electroform 22 against molding pressure deformation forces and transmit the same from electroform 22 through chamber 64 to the mold frame, shell 60.
Alternatively, as diagrammatically illustrated in Fig. 9A by the modified sixth embodiment of mold half 89, a plurality of support pillars 90 and 92 are constructed of hollow or solid sintered materials having porosity of a suitable nature so that they also function as a supplementary wick to help replace the charge fluid at the evaporator of condenser site.
Figs. 9B and 9C illustrate a seventh embodiment mold half 94 having support pillars 95 and 98 constructed from perforated tubes so as to permit the incursion of charge vapor into those regions inside the support tubes. Additional wicking materials 100 may be placed along the tube LD. to transfer the charge fluid to the evaporator or condenser sites.

The eighth embodiment mold half 104 of Fig. 10 may be provided in those instances where the molding operational thermal demands on the assembly exceed the ability of the wick to replace the charge fluid at the evaporator site. To alleviate this condition the charge fluid is positively pumped to the evaporator site using an external bellows pump 106 and associated liquid suction lines 108 and 110 and liquid feed lines 112-120 organized as a liquid phase positive pressure feeding circuit as diagrammed in Fig. 10 to supplement capillary wicking action.
In orientations and applications that require both the use of a charge fluid pump 106 and support pillars 96, 98, these perforated support pillars may be provided to act as dispersion nozzles and/or evacuation outlets for incoming and/or outgoing charge or working fluids, as shown diagrammatically in ninth and tenth embodiment modified mold halves 130 and 140 of Figs. l0A and lOB respectively (chamber fluid return lines and pump not being shown in Fig. lOB).
Figs. 11 and 11A show another eleventh embodiment variation of the method and apparatus of the invention for producing a heatpipe mold half 150 having a modified fabricated heatpipe end cap 22 made by using any high strength metal or alloy material that can be machined to satisfy the conditions of a molding surface and made to a reasonably constant cross sectional thickness. The metal or alloy molding surface end cap 22" is then attached to a shell 60 of suitable size and provided with an evacuated chamber 64, charge fluid 40/50 and appropriate wick material 66. If the molding surface end cap 22" (and also, if desired, shell 60) are made of alloy steel or other metallic material that will cause incompatibility with the charge fluid, i.e., possibly cause non-condensable gases to develop in chamber 64, then the interior surfaces of the evacuated chamber 64 must be plated with an inert elemental metal 152, such as nickel or copper, prior to the evacuation of chamber 64 and the introduction of the charge fluid.
The evacuated shell heatpipe half mold technology of the invention thus envisions a core or cavity face of a mold half as a complete mold face which is also one face of the heatpipe that encompasses all or substantially all of the total molding surface or wetted surface or working surface of the mold. In the case of molds having both male and female molding faces (also referred to respectively as cavity and core molding surfaces as in Fig. SA) one face of a unitary heatpipe construction makes up the total male or core face of the mold and one face of another unitary heatpipe construction makes up the female or cavity face of the mold. Fig. 12 illustrates this principle applied to a compression mold assembly 160 with separable mold nests 162 and 164 carrying heatpipe mold halves 70 and 72 respectively.
In two further variations illustrated in thirteenth and fourteenth embodiment mold halves 170 and 180 of Figs. 13 and 13A respectively, the electrofolin may be produced in such a way that it functions as an integrated heatpipe end structure and heatpipe shell structure. To accomplish this end result, a plurality of conventional pre-made copper or nickel heatpipes 172 are used in mold half 170, and likewise such heatpipes 182 in mold half 180, and are incorporated as a mutually bonded array integrally with the electroform material during the plating process. The array of heatpipes is positioned such that the heatpipes may reside entirely within the electrofolm structure (Fig. 13) or such that their ends remote from the molding surface extend beyond the bottom surface of the structure (Fig. 13A).
The individual heatpipes 172, 182 are closely nested in their respective integrated array in such mold half so as to occupy the maximum possible volume of the electroform geometry. Preferably the heatpipes longitudinal axes are mutually parallel and perpendicular to the general plane of the molding surface and/or mold parting line plane.
The heatpipe array is preferably also substantially co-extensive in projected area with all or alinost all of the area of mold surface 24'. The amount of plating material required to encapsulate the heatpipes is thereby reduced while the closely nested array functions to maximize heat transfer uniformity at the molding surface to the fullest extent possible when using such discrete heatpipe elements encapsulated in this embodiment of an electroform heatpipe mold half of the invention. In some applications the material encapsulating the plurality of nested heatpipes may be heat conductive ceramic or composite materials, the overall heat transfer coefficient thereof being greatly enhanced by the encapsulated heatpipe nest.
A further variation in the construction of the heatpipe chamber mold half of the invention is to utilize non-metallic heat conducting materials such as heat-conductive-type ceramics or composites to form the molding surface end cap, and also for forming the half mold shell, and to electroplate the interior chamber-defining surfaces of these components with a material such as elemental nickel that is inert to the reactions occurring in a heatpipe. When joined together with the wick structure and sealed, a charge fluid can be installed, and the chamber evacuated; thus creating another form of a heatpipe half mold unit of the invention.

This same evacuated shell heatpipe mold technology may be used to heat or cool molding surfaces in slush molds, reaction injection molds, resin transfer molds, pot molds and in all other forms of molds and tools where a liquid or semi-solid molding material is introduced into a void created by a number of solid metallic or non-metallic mold blocks or shapes having molding surfaces that contain the impression of a part. The liquid or semi-solid molding material is injected or otherwise introduced into the void in sufficient volume and there it is either heated, cured or cooled so as to produce a finished molded part with a shape and configuration that fills the void and has outside dimensions and geometry that are the exact reverse of the heatpipe molding surfaces described above. In accordance with the invention, such molds in whole or in part preferably utilize electroforms or fabricated molding surface parts having a generally constant cross-sectional thickness to provide both the molding surface and heatpipe chamber end wall.
It should be also be understood that the heatpipe chamber can be of irregular shape. Further, the protruding ends of the heatpipe array of FIG. 13A can all be disposed in another heatpipe chamber encompassing all of such protruding ends. It should be further understood that a common heatpipe chamber will selectively cool or heat that portion of the mold cavity surface that exhibits the highest 0 T between the mold charge and heat chamber.

Claims (28)

1 CLAIM

A method of making a mold half part comprising the steps of:
(a) forming a molding surface structure having a first surface with a molding surface contour for defining exterior contour of a part to be molded thereagainst, (b) forming said molding surface structure so as to have a second surface remote from said first surface and defining therebetween a generally constant cross-sectional thickness dimension of said structure in a direction generally perpendicular to the plane of the parting line in which the mold half is to be utilized, (c) fastening heatpipe chamber means to said mold surface structure oriented and operable for phase change heat transfer to or from said first surface via said structure and second surface, and (d) providing said heatpipe means in a configuration to encompass substantially all of the area of said first molding surface projected in a direction perpendicular to the aforementioned parting line of the mold.

2.

The method of claim 1 wherein said heatpipe chamber means comprises an open ended shell having side walls joined to a first end and having a second end closed by said molding surface structure, so as to define a single chamber at least generally co-extensive and subjacent to the molding structure first surface, and wherein said chamber is sealed, evacuated and optionally lined with wick material and charged with a suitable fluid and thereby rendered operable to function as a heatpipe.

3.

The method of claim 2 wherein said shell is provided with cooling means in heat transfer relation with the shell walls.

4.

The method of claim 2 wherein said shell is provided with heating means in heat transfer relation with the shell walls.

5.
The method of claim 2 wherein a plurality of support pillars are provided in the heatpipe chamber extending longitudinally in a direction perpendicular to the parting line plane of the mold part between and in supporting relation to said molding surface structure and the bottom wall of said shell to statically support said mold surface against deformation when the same is subjected to molding pressures in the operation of the mold part in a mold cycle.

6.

The method of claim 5 wherein said support pillars are made in the form of hollow sintered inert metal to act as a supplementary wicking material in said heatpipe chamber.

7.

The method of claim 5 wherein said support pillars are made as in the form of hollow metal tubes with perforations through the wall of each such tube and with wicking material contained in the interior of each such tube.

8.

The method of claim 2 wherein the wick material lining the interior surfaces of the walls of the chamber is augmented by providing a charge fluid pumping system having liquid evacuation conduit means communicating with lower-most portions of the chamber and having liquid feed conduits extending into the chamber to act as flow fountains to admit liquid phase change fluid replenishment to the chamber to assist wetting of the evaporation sites in the heat chamber.

9.

The method of claim 8 wherein the one or more of the feed conduits of the supplemental charge fluid pumping system are provided to communicate with the interior of one or more of the perforated support tubes such that the same also act as a dispersing nozzle or nozzles for the incoming liquid phase charge fluid entering the chamber.

10.

The method of claim 8 wherein one or more of the hollow perforated support tubes are connected to one or more of the evacuation conduits of the supplementary charge fluid pumping system so that the same also act as charge fluid liquid phase evacuation outlets from the heatpipe chamber to the supplementary pumping system.

11.

The method of claim 1 wherein said molding surface structure is machined from a workpiece blank made of high strength, relatively inexpensive metallic material such as steel, and wherein the second surface thereof facing the heatpipe chamber means is plated with an elemental metal and then covered with a wicking material.

12.

The method claim 1 wherein said heatpipe chamber means is made by forming a side-by-side nesting of a plurality of pre-existing or pre-made heatpipe elements in an array having lateral dimensions at least generally co-extensive with the lateral dimensions of the first surface of the half mold part when finished, and then encapsulating the heatpipe elements with a mold-forming material provided with said mold-cavity-defining first surface adapted to operate against a parting line plane extending perpendicular to the longitudinal axes of the array of heatpipe elements.

13.
The method of claim 12 wherein said heatpipe elements are completely encapsulated in said encapsulating material of the half mold part.

14.
The method of claim 12 wherein said heatpipe elements protrude at one end thereof from a face of the encapsulating material remote from the molding first surface thereof.

15.
Apparatus constructed and arranged as a mold half part comprising:
(a) means forming a molding surface structure having a first surface with a molding surface contour for defining exterior contour of a part to be molded thereagainst, said molding surface structure also having a second surface remote from said first surface and defining therebetween a generally constant cross-sectional thickness dimension of said structure in a direction generally perpendicular to the plane of the parting line in which the mold half is to be utilized, and (b) heatpipe chamber means operably connected to said mold surface structure and being oriented and operable for phase change heat transfer to or from said first surface via said structure and second surface, [providing) said heatpipe chamber means encompassing substantially all of the area of said first molding surface as projected in a direction perpendicular to the aforementioned parting line of the mold.

16.
The apparatus of claim 15 wherein said heatpipe chamber means comprises a cup-like or box-like shell having side walls joined to a first end wall and having a second end wall opposite said first end wall formed by said molding surface structure so as to define a single chamber at least generally co-extensive and adjacent to said molding structure first surface and exposed to said second surface, and wherein said chamber is sealed, evacuated and lined with wick material and charged with a suitable fluid and thereby rendered operable to function as a heatpipe.

17.
The apparatus of claim 16 wherein said mold half part includes cooling means in heat transfer relation with said shell walls.

18.
The apparatus of claim 16 wherein said mold half part includes heating means in heat transfer relation with said shell walls.

19.
The apparatus of claim 16 wherein a plurality of support pillars are provided in said heatpipe chamber extending longitudinally in a direction perpendicular to the parting line plane of the mold part between and in supporting relation to said molding surface structure and said first end wall of said shell to thereby statically support said first mold surface against deformation when the same is subjected to molding pressures in the operation of the mold part in a mold cycle.

20.
The apparatus of claim 19 wherein said support pillars are made in the form of hollow sintered inert metal to act as a supplementary wicking material in said heatpipe chamber.

21.
The apparatus of claim 19 wherein said support pillars are made as in the form of hollow metal tubes with perforations through the wall of each such tube and with wicking material contained in the interior of each such tube.

22.
The apparatus of claim 16 further comprising a charge fluid pumping system having liquid evacuation conduit means communicating with lower-most portions of the chamber and having liquid feed conduits extending into the chamber to act as flow fountains to admit liquid phase charge fluid replenishment to said chamber to assist wetting of the evaporation sites in the heat chamber for thereby augmenting said wick material lining the interior surfaces of said walls of said chamber

23.
The apparatus of claim 22 wherein one or more of said feed conduits of said supplemental charge fluid pumping system communicates with the interior of one or more of said perforated support tubes such that the same also act as a dispersing nozzle or nozzles for the incoming liquid phase charge fluid entering said chamber.

24.
The apparatus of claim 22 further comprising a supplementary charge fluid pumping system having one or more evacuation conduits connected to one or more of said hollow perforated support tubes so that the same also act as charge fluid liquid phase evacuation outlets from said heatpipe chamber to said supplementary pumping system.

25.
The apparatus of claim 15 wherein said molding surface structure comprises a machined workpiece blank made of high strength, relatively inexpensive metallic material such as steel, and wherein said second surface thereof facing the heatpipe chamber means is plated with an elemental metal and then covered with a wicking material.

26.
The apparatus of claim 15 wherein said heatpipe chamber means comprises a side-by-side nesting of a plurality of pre-existing or pre-made heatpipe elements in an array having lateral dimensions at least generally co-extensive with the lateral dimensions of said first surface of said half mold part when finished, said the heatpipe elements being encapsulated with a mold-forming material having said mold-cavity-defining first surface adapted to operate against a parting line plane extending perpendicular to the longitudinal axes of said array of heatpipe elements.

27.
The apparatus of claim 26 wherein said heatpipe elements are completely encapsulated in said encapsulating material of the half mold part.

28.
The apparatus of claim 26 wherein said heatpipe elements protrude at one end thereof from a face of the encapsulating material remote from said molding first surface thereof.