Abstract: The steam platen comprises spaced flat horizontal exterior walls each having a horizontal outside surface, and concentric cylindrical walls, one an inside wall and the other an outside wall both of which extend from the first to the second flat wall. The first flat wall abuts a mold half and the second flat wall abuts a supporting structure such as a base or a head, and these flat walls may be termed a mold sidewall and a bolster sidewall respectively. The interior space between the first and second flat walls has a plurality of partitions which extend from one flat wall to the other and which form one or more continuous serpentine steam passages which constitute a steam cavity. This steam cavity covers the entire area of the mold and is devoid of dead spots, so that the mold sidewall is heated by the steam to an essentially uniform surface temperature. For ease of fabrication, the platen may be formed as two separate pieces, i.e.

Abstract: A mold assembly for molding thermoplastic particles into a solid thin shell includes a metal shell having a cavity and including an outer surface exposed to a heat source and further including an inner surface on which thermoplastic material is cast and fused to form a thin layer thermoplastic shell. The heat transfer area of the metal shell is increased by providing a plurality of heat transfer pins connected to the outer surface; each of the heat transfer pins has an extended outside surface area exposed to the heat source for heating the metal shell and each of the heat transfer pins further includes a large diameter head portion which is joined to the metal shell by a capacitive weld nugget formed solely between the large diameter head portion and the outer surface of the metal shell without disrupting the metal shell at surface portions thereof formed between the heat transfer pins.

Abstract: A die assembly for die casting a propeller structure, such as a wax propeller pattern. The pattern, which is identical in configuration to a cast metal propeller to be produced, includes a generally cylindrical hub having an outwardly flared end and a plurality of blades project outwardly from the hub. The die assembly includes a base plate and a lower core section extends upwardly from the base plate through an opening in a stripper plate, which is mounted for movement toward and away from the base plate. A plurality of die sections are mounted for generally radial sliding movement on the stripper plate from an outer open position to a closed position where they define a die cavity with the core section. The die assembly also includes an upper die unit that is mounted for vertical movement and has a cavity in its lower surface which receives the upper ends of the die sections when in the closed position.

Abstract: An injection mold for injection-molding a tubular article having a bottom at one end and opening at the other end having a cavity plate and a core which define a cavity conforming to the shape of the article when closed. A gate opens to the cavity at a portion defining the bottom of the article. The core is provided with a coolant passage for circulating coolant up to a portion near the free end surface of the core for defining the bottom of the article. The inner surface of the core defining the end portion of the coolant passage near the free end surface of the core tapering toward the gate and the coolant passage extends near a portion of the free end surface of the core opposed to the gate, and at least one rib is provided on the inner surface of the core at the tapering portion to project into the coolant passage and to extend in parallel to the direction of coolant flow.

Abstract: A press platen, for bonding ends of a conveyor belt, having both heating and cooling means, the heating means being electrical resistance elements positioned in grooves bars, within the platen, which bars also define cooling channels therein.

Abstract: A cooling apparatus for an injection molding machine, which is used to form hollow parts, employs mating mold dies with first and second corresponding hollow core members attached to the dies and extending into the mold cavity. When the cavity is closed, the hollow core members engage to form a continuous cooling fluid passageway through them. During the molding operation, liquid cooling fluid is supplied under pressure to flow through this passageway. At the end of the molding cycle, the flow of cooling fluid is blocked and a second valve is opened to admit air into the passageway near the point where the two hollow core members engage. A vacuum is applied to the opposite ends of both of the hollow core members to pull any cooling fluid and air from the junction between the core members and away from the junction back through the core members.

Abstract: A sintering device includes separable mould walls which together define a mould cavity and a mould core which is positioned within the cavity to define an undercut mould surface. The core includes a hollow frusto-pyramidal central support formed with guideways and a plurality of core segments mounted for slidable movement within the guideways whereby the core is radially expandable and contractable. The segments include a plurality of arc-surface segments alternating with trapezoidal segments. The mould walls and the core include passages for introducing steam and air into the cavity. The passages of the core place the hollow interior of the central support in communication with the mould cavity.

Abstract: A mold suitable for casting therein molten metal or other molten materials wherein the mold includes a heat exchange surface, the mold includes means for providing a flow of coolant liquid to remove heat from the heat exchange surface by formation of nucleate vapor bubbles on the heat exchange surface, the liquid tending to include a viscous sublayer adjacent to the heat exchange surface, the improvement wherein the heat exchange surface includes at least one of: means for forming pressure gradients in the liquid having a component perpendicular to the heat exchange surface to facilitate removal of the nucleate bubbles; and means for breaking up the viscous sublayer to facilitate removal of the nucleate bubbles, and wherein the heat exchange surface comprises a series of concave curved surfaces and wherein septum members with corresponding curved surfaces, which may be split to permit positioning into close proximity to the heat exchange surface to provide desired coolant flow characteristics over the surface

Abstract: Apparatus for forming a hollow blow-molded container utilizes a mold having at least one wall insert for forming a collapse panel in a container.

Abstract: A porous die includes a porous die body with a plurality of pores formed therein; a cooling chamber provided in direct contact with the back side of the porous die body in order to cool the porous die body; a device for supplying a coolant to the cooling chamber; and suction holes through which the cooling chamber is evacuated and the air and the coolant entering the cooling chamber are simultaneously sucked.

Abstract: An injection mould having several gating points (3) which are all supplied with moulding material at the same time has a hot runner manifold (2) situated in a composite body. The composite body is composed of several plates (9,11,12,13,9') in which both the system of hot runners (2) and the tubular heating elements (10) required for heating are formed, starting from the surfaces of separation (F1, F2, F3, F4), whereupon the individual surfaces are joined together by diffusion welding after they have been pretreated as required (FIG. 2).

Abstract: Apparatus for molding a thermoplastic tubular product such as a bushing having an internally threaded major diameter portion and an integral truncated minor diameter portion. A mold provided with a mold shell which jointly with a two-part mold core defines a mold cavity having a shape complementary to the shape of the molded bushing. The molded bushing has an internal undercut in the form of a thread in the major diameter portion thereof. The mold core is made as a core pin and an externally threaded sleeve of greater diameter than the core pin circumferentially of a portion of the core pin. Provision is made for moving the mold elements relatively to define the mold cavity and to effectively release the core by axial compression of the molded product while exposed on the mold core to cause it to swell radially outwardly and release the externally threaded core which forms the internal thread on the molded bushing.

Abstract: A mold has mold walls defining a cavity and a plurality of heated fluid inlets communicating with the cavity. An enclosed frame for storing a heated fluid is positioned about the mold. Valves are positioned completely within the enclosed frame and each of the valves is coupled to one of the heated fluid mold inlets.

Abstract: The invention relates to a collapsible core for a mould. The core comprises three relatively movable assemblies. The first assembly carries a cone, the second assembly carries an inner set of segments which form part of the core surface and engage the cone and the third assembly carries outer segments moved by inclined pins on the second assembly. As the assemblies are moved together the outer segments move radially outwards and the inner segments move axially in between them. Then the inner segments move radially outwards and the cone fills the center of the core. On reversal of the movement, the core is collapsed to enable it to be withdrawn from the moulded article.

Abstract: A molding cavity wall (10) is made in a plurality of parts of a cheap material having a high thermal conductivity, for example a thin metal sheet (10), at least one heating device (11) is applied on the wall in direct thermal exchange relation to the external surface of the wall (10), and a thermal insulator constituted by a foam (12) of highly rigid resin is applied to the wall (10) in uniform pressure transmitting relation to said wall.

Abstract: A resin injection metal mold unit comprising, in combination, a metal mold consisting of a cavity section and a core section, and stationary and movable metal mold supporting members for releasably holding the metal mold sections in the opposing relationship. Each supporting member has a plurality of clamping members for engaging an associated mold section. Each clamping member has a clamping slant in the complementary relationship with the counter slant chamfer of the mold section. Such members are slidably attached to an associated supporting member so as to move close and apart from the mold section. When a mold section is fixed to an associated supporting member, the clamping members are brought in contact with the mold section with their clamping slants closely fitting the counter chamfer slants of the mold section, and then clamping members are fixed to the supporting member by driving associated bolts, thereby pushing and holding the mold section against the supporting member.

Abstract: The invention relates to the tooling for claw cages for ball bearings comprising a mold proper and an impression unit adapted to be placed inside said mold, said impression unit comprising a crown and a plurality of balls limiting a mold cavity defining a bridge, recesses and claws of such a cage. Said impression unit is produced in several parts adapted to be made fast to one another, shaped to provide a multiplicity of recesses each having substantially the shape of a portion of a spherical cap, so that when said parts are assembled said recesses provide a multiplicity of substantially spherical housings in each of which a ball is received held in a pre-established position determining with accuracy a hollow and claws of said mold cavity. The invention is useful for the manufacture of ball bearings.

Abstract: A spacer core for use in constructing hollow concrete walls by introducing the core between and spaced from a pair of vertical mold plates before casting the wet concrete, and subsequently removing the spacer core, the lower end of the spacer core including a water permeable wall and a bottom chamber for accumulating water permeating the wall. Also described is a method of constructing hollow concrete walls by the use of the above spacer core by: introducing the spacer core between and spaced from a pair of vertical mold plates; casting wet concrete into the spaces between the spacer core and the mold plates, whereby the water from the concrete permeates through the bottom of the spacer core into the bottom chamber; after a first time interval, lifting the spacer core a first predetermined distance to draw water from the concrete into the bottom chamber; and subsequently removing the spacer core from the concrete.

Abstract: Molten oxide of grinding material, refractory material, etc., being poured into a circular casting space formed between coaxially arranged inner and outer cylinders and cooled by the water contained in the inner cylinder. Thus, the molten oxide is cooled radially from the center of the inner cylinder and solidified. The outer cylinder includes two segments which separate from each other for facilitating putting the molten oxide into the casting space and taking the resulting solidified product out of the casting space.

Abstract: Graphite mold blocks with liquid coolant sprays located in bores extending through the blocks. A sleeve for retarding the cooling of the mold adjacent the spray entrance ends of the bores serves to reduce the temperature differential along the height of the block.

Abstract: This invention relates to a two-way cooling pipe for cooling a die or mold which is used for die casting or a similar forming process. This pipe is a hollow pipe, the interior of which is divided axially by a baffle which provides a forward channel and a backward channel for the cooling water to pass. Cooling of the die is achieved by feeding cooling water to the inside of the die from the forward channel in the cooling pipe which has been inserted in the die from the back thereof, and then removing the cooling water through the backward channel of the cooling pipe.

Abstract: Proposed is a method for the erection of structures, such as bridges, that display pre-fabricated concrete beams, according to which the individual pre-fabricated beams are produced, on the spot, on a feed rigging within the corresponding work area of the structure, in a heated and laterally tiltable form. After removal from the form, the thusly produced pre-fabricated beams are transferred sidewardly into their final position by means of gantry cranes. During concretizing of the individual pre-fabricated beams, flexure of the feed rigging carrying the form is equalized in continuous fashion, in correspondence with the progressing, concretizing process, by transfer pumping of ballast liquid.

Abstract: A device for the program-controllable exchange of injection molding dies and for the continuous preconditioning of an injection molding die, prior to and during its insertion into the die closing unit of an injection molding machine, comprising a translation table with two die emplacements which are alternatingly movable into transverse alignment with the die clamping space, for transfer of a die assembly by means of an endless roller chain with drive pins and a drive rack entraining the die assembly. Each die emplacement has a captive drive rack which carries a coupling head for flexible temperature conditioning supply lines and each die assembly has a matching coupling head with coupling valves and an identification code incorporated in a multi-conductor connection, all connections being established by the mere lowering of the die assembly onto its die emplacement.

Abstract: The apparatus consists of a vessel that is transparent to microwaves, an inner coating of material that is heated by microwaves and a coating inside that that will reflect microwaves.In use the user allows his mold substance to set in the ordinary way. When he desires to release his moldable from the molded substance he applies microwaves to the outside of the vessel. The waves pass through the outer transparent wall and heat the inner coating. Conductivity of heat causes the surface of the molded object to be heated, to liquefy and release from the mold. The innermost layer of reflective substance prevents the microwaves from penetrating into the molded object and heating the whole molded object.What is new is an apparatus that will permit the user to quickly and conveniently release a molded object from a mold without any risk that he will heat and destroy portions of the molded object.

Abstract: A machine for molding sheets of foamed material includes an upright stationary steam chest having opposing perforated external faces, and a pair of movable assemblies abuttable with the opposite faces of the steam chest to define mold cavities therewith. Each cavity forming assembly includes a mold frame extending normal to a face of the steam chest, and a platen positioned within and coupled to the mold frame. Jackscrews move each mold frame into and out of abutment with the steam chest, and also move each platen relative to its respective mold frame toward and away from the steam chest. A method of molding sheets of foamed material is also disclosed wherein heated polystyrene beads are squeezed by the movable platens to a predetermined thickness to provide a board having the desired dimensions and density.

Abstract: A device for reopening an ice-bound water source is disclosed. Once a hole is provided in a frozen water source, the tubular member is inserted into the hole where it becomes frozen in place. The ice block which will form in the interior region (28) of the tubular member can be ejected. The tubular member itself is heated by a fluid circulating and heating means (62) which runs heated fluid between the walls (20 and 22) of tubular member (12). The heated fluid allows for release of the ice block and dislodgment of the entire unit from the frozen surface of the water supply.

Abstract: A mold for forming a recorded disc includes a base plate and a cap plate mounted on the base plate. Bolts extending through the base plate and threaded into the cap plate secure the outer portions of the plates together. A hub projecting from the cap plate extends through a hole in the base plate and a nut threaded on the hub and engaging a surface of the base plate secures the inner portions of the plates together. The cap plate has a plurality of sets of grooves in its inner surface which mates with a surface of the base plate. The grooves in each set are radially spaced, concentric, circular grooves connected by slots. An inlet passage extends through the base plate to one of the grooves of each set and an outlet passage extends through the base plate to a groove of each set to provide for a separate flow of a temperature control medium through each set of grooves. The base plate and cap plate are made of materials having suitable physical properties for the specific plate.

Abstract: A method for manufacturing a heat-insulating member, such as e.g. a door or housing of a refrigerator, including a shell and a foamed heat-insulating material filled in the shell and a jig used therefor. The jig is intended to hold the shell lest the shell of the heat-insulating member to be manufactured should be deformed when a foamable liquid composition is foamed in the shell. In the jig of this invention, a jig body is formed of a heat-insulating material. The method of this invention comprises the steps of holding the shell in a hollow state by means of two jigs, injecting the foamable liquid composition into the shell to foam the same in the shell. Since the jig body of the jig of this invention is made of a heat-insulating material, the necessity of external heating, which is essential to the conventional method, is substantially obviated.

Abstract: A center plate for an apparatus for molding recorded discs is disclosed which includes a cylindrical body having an internal recess and a plug secured across the bottom end of the recess. The plug has a pair of passages therethrough opening into the internal recess. An adapter is secured to the plug. The adapter has a pair of ports and a separate universal connection between each of the ports and a separate one of the passages in the plug. This provides for a flow of a heat control medium through the center plate and permits ease of connecting pipes to the ports to provide the flow of the heat control medium.

Abstract: An improved molding apparatus for expanding beads of polystyrene material into large blocks in the manufacture of insulating material. The mold apparatus has walls made from a plurality of tubular wall members arranged in horizontal, side-by-side relation. The wall members are mounted transversally within encircling frames. Steam is supplied to each wall member, and from within each wall member, into the mold cavity to expand the polystyrene beads held therein into a block. An improved device is also provided to remove the block from the mold cavity.

Abstract: A mould for producing profiled elements of plastics material, notably in building joinery frames, comprises upper and lower half-moulds which are separated by a joint plane and respectively associated with tightening means, namely the plates of a press and define together the impression of a profiled element to be moulded from said plastics material. Each of said half-moulds has lateral faces parallel to said profiled element and transverse ends and comprises a shoe having an outer surface including removable fastening means cooperating with said tightening means and an inner surface parallel to said joint plane and forming the bottom of said impression. Interchangeable profile-defining members are respectively fixed to said inner surface and form the sides of said impression, thus permitting the production of a large variety of profiled elements for a very low cost price whilst being easy to produce.

Abstract: Portable ice making container apparatus is provided for making blocks of ice. An inner container is used to receive water which is to be frozen to form a block of ice. A larger outer container is provided to receive and support the inner container therein. Support posts are provided at the bottom of the outer container to position the bottom of the inner container a short space above the bottom of the outer container. Flanges are disposed at the tops of both containers to interconnect the containers for the purpose of maintaining them in a nested, spaced-apart relationship. A cover member has walls constructed to fit snugly against the walls of the inner container to enclose the top of the inner container. The walls extend downward to a common bottom to form a recess for containing fluid to warm the bottom of the cover member. The outer container includes receptacles at the corners for receiving fluid to be dispersed throughout the space between the inner and outer containers.

Abstract: Method and apparatus for providing a controlled pressure liquid circulation system comprising a circulation conduit through which a liquid can be circulated and recirculated to accomplish a desired function, such as heating and/or cooling of a work station such as a mold. The invention involves opening and closing said circulation conduit to a source of supply liquid, such as city water, at elevated pressure while maintaining the controlled pressure of the liquid within said circulation conduit at a substantially lower pressure, and is characterized by maintaining the circulation conduit open to a drain line at all times and providing or maintaining a drain pressure which is at least slightly above atmospheric and is equal to the pressure desired within the circulation conduit in the area thereof which is open to the drain.

Abstract: A cellular polymeric resin sheet, slab or the like is produced by filling a pressure resistant receptacle having a cover directly releasably locked thereto with a uniform mixture of a resin such as polyvinyl chloride, a finely divided heat activated first gas generator and preferably a water activated second gas generator together with other additives such as plasticizers, stabilizers, etc. The closed receptacle is heated to effect the gelation and fusion of the resin and the activation of the first gas generator to produce a high density uniform small pore cellular resin body embryo under high pressure in the receptacle. The receptacle and embryo are cooled, the receptacle opened and the embryo removed and subjected to a high humidity atmosphere, preferably at elevated temperature to activate the second gas generator and react therewith.

Abstract: A novel method and device for precision injection molding is disclosed providing controlled cooling of a portion of the mold cavity surface during the molding cycle, or several such portions independently, and also, in the preferred embodiment controlled heating of a portion of the mold cavity surface during the molding cycle or several such portions independently, whereby high quality, high precision parts having close dimensional tolerances may be produced. Another aspect of the invention, a volume-controlled variable conductance heat pipe is disclosed, which novel heat pipe comprises housing means forming a sealed chamber, fluid, such as water or ammonia, within the chamber, wicking means and control means for controlling the thermal conductance of the heat pipe comprising means for controlling the volume of fluid in the liquid phase in the chamber.

Abstract: This invention relates to a mold for molding prefoamed material of thermoplastic synthetic resin, in which the foamed product is provided with a smoothened superficial skin layer on the overall surface thereof, a beautiful external appearance and a remarkable strength. The mold according to this invention consists of a pair of molds each of which is provided with an internal wall facing to a cavity and an external wall not facing to the cavity, and either one of or each of which is provided with at least one heating chamber including a steam inlet and a steam outlet both of which are mounted in the external wall. And either one of or each of the two molds is provided with a plurality of steam passages and a surface-heating chamber independent thereof both of which are mounted in the internal wall.

Abstract: This invention relates to a cooling process suitable for foam molding of a synthetic resin and its cooling apparatus. Cooling water which is supplied into a flowing pressurized gas is turbulently jetted in the form of a mist into the overall area of respective chambers in a pair of molds. The mist, adhering uniformly to the overall walls of the molds remove latent heat from the mold surface, and consequently uniformly cool the entire mold. Further, a large quantity of steam generated from the mist as well as excess mist are forcibly discharged outside the chambers by a preferred suction means including a blower, etc., whereby the cooling effect on the walls of the molds is further enhanced.

Abstract: Molding of expanded plastic material such as dielectric material by microwave radiation is effected in a mold in which the part of the mold which contacts the material to be molded is of a material having high dielectric losses and capable of absorbing microwave radiation. Such mold portion preferably comprises a resin containing a small amount of carbon black.

Abstract: Mold for the injection molding of objects of large dimension and complicated surfaces from plastic material without internal stresses and with accurate dimension. In base plates of the mold cooling grids are embedded and the active surface of the base plates is provided with forming plates and forming strips with grooves for heating elements or tempering and cooling means. The mold is provided with mobile cores which change their positions in the course of shrinking of the solidifying plastic material.

Abstract: A negative pressure cooling system for cooling passageways in plastic molds includes a closed reservoir that is maintained under a high vacuum by a vacuum fluid pump with the outlet of the cooling passageway being connected to the reservoir inlet and with the reservoir outlet being connected to the cooling passageway inlet through a pressure pump and a fluid pressure regulator.

Abstract: A method and system for cooling a mold, including the steps of providing fluid flow connectors insertable into a mold for conducting the coolant into the mold. One of the connectors is made in one-piece and includes a threaded stem which threads into a mold opening, and that one-piece also includes two threaded openings which are disclosed transverse to the length of the stem and which align with passageways in the mold for attaching to two tubes extending in the passageways. The system in method is arranged for the alignment of the threaded openings with the passageways while the stem is fluid tightly threaded into the mold opening, and all of these connections are made on the interior of the mold.

Abstract: A platen capable of being heated is disclosed wherein fluid flow zones containing heat exchange channels are individually sealed. The heat exchange channels in the platen are connected by a connecting channel sized so that the distance from the connecting channel to a vent passage or a vented opening in the platen is not less than the distance from the vent passage or vented opening to the heat exchange channel. The sealing of the fluid flow zones is accomplished with plugs and end plates which are welded to the platen and then welded together with a fillet weld.

Abstract: A vented platen capable of being heated or cooled is disclosed wherein a plurality of heat exchange channels bored through the width of a plate member are arranged in a plane. The plate member has a plurality of openings on a surface that are vented by vent passages disposed on a plane substantially parallel to the plane of the heat exchange channels.

Abstract: Heated material is injected into an annular cavity, defined by a pair of mold halves, through a sprue passage, defined by a sprue bushing and an end portion of a punch. The annular cavity and the sprue passage form, respectively the centrally apertured part and a sprue. After partial cooling of the heated material, the punch is locked in place while the annular cavity is displaced relative to the sprue passage so that the sprue is severed from the part along the peripheral surface of the punch end portion. The mold halves are separated to open the annular cavity while the sprue is resting on the punch end portion, and while the part is held by the punch end peripheral surface. After the mold halves are separated, a sprue ejector member is actuated to eject the sprue from the punch end portion. The finished video disc is then removed, carried by the moving platen of the moving mold assembly.

Abstract: A press mold half for producing records comprises a mould half having a psing surface thereon, and a channel system beneath the surface for conducting heating and cooling fluids in indirect heat transfer relationship with the surface. The channel system includes spaced apart inflow and outflow fluid collecting chambers, and a number of channels extending over given paths between the chambers, the overall cross section of the channels in regions adjacent the outflow collecting chamber is less than the smallest overall cross section of the channels over the remainder of their paths, thereby resulting in uniform heating and cooling of the material being pressed.

Abstract: A heated mold panel for casting concrete has a rigid base providing a base surface, a substantial part of which is grooved by interconnecting grooves, has a continuous heating element laid in the grooves, and the base surface is covered with a non-porous, non-corrosive material that provides a smooth outside surface covering the base surface, spanning the grooves and enclosing the element in interconnecting passages defined by the grooves and the covering material. Sufficient clearance is provided in said passages around the element for air to flow freely from passage to passage, whereby heat flow from the element to the concrete poured against the outside surface is by radiation from the element and by convection of air flowing in the passages around the element.

Abstract: The invention provides an improved cooling arrangement for the core pin of a commercially available injection molding machine permitting a significant reduction in the cycle time of such machine. The core pin is fabricated by the assembly of a plurality of concentric sleeve-like members, one of which is provided with six parallel helically disposed external grooves which respectively define three parallel passages for cooling fluid inlet and three parallel outlet passages for the heated fluid. The arrangement provides a significant increase in the quantity of cooling fluid flowing through the core pin, hence permits a significant decrease in cycle time of the injection molding machine.

Abstract: A method of curing a polymeric hose are provided wherein a hose to be cured is confined within a tubular preformed spiral confining wall of a mold structure to thereby provide optimum support for the exterior surface of such hose during curing which assures provision of a precision outside surface yet enables curing of a substantial length of hose in a comparatively compact volume.

Abstract: A toy molding apparatus having a housing or container with a heat source therein surrounded by a heat directing baffle member, at least a portion of the baffle member being configured for receiving a plastic squeeze bottle containing a gelatinous substance therein, the substance being generally solid at room temperature and approaching a liquid state at approximately 105.degree. Fahrenheit. The bottle is positioned within the receptacle for heating by the heat source and upon reaching a fluid state it is poured into a separate mold member to set upon cooling.

Abstract: A method and apparatus for forming a continuous cooling liquid passageway through two separable injection mold dies when they are closed with a supply system flowing cooling liquid at a less than atmospheric pressure at least at the junction of the dies through the passageway only when the dies are closed and air when the dies are opened and the passageway is discontinuous.