HK1100030A - Method and apparatus for coupling melt conduits in a molding system and/or a runner system - Google Patents

Abstract

Method and apparatus for a molding melt conduit and/or runner system includes coupling structure having a first surface configured to couple with a first melt conduit or manifold, and a second surface configured to couple with a second melt conduit or manifold. Cooling structure is configured to provide a coolant to the coupling structure. Preferably, the cooling structure cools the coupling structure to a temperature that causes any melt leaking from near the coupling structure to at least partially solidify thereby further sealing the connection(s).

Description

Method and apparatus for coupling melt conduits in a molding system and/or runner system

Technical Field

The present invention relates to a melt conduit coupler for providing a leak-reducing connection between discrete melt conduits in a molding system. In particular, the melt conduit coupler of the present invention may be configured for interconnecting melt conduits in a runner system of an injection molding machine. More particularly, the runner system may comprise a hot runner configured for metal injection molding.

Background

The present invention relates to the molding of metal alloys (e.g., magnesium) in a semi-solid or fully liquid state (i.e., above the solidus). A detailed description of exemplary equipment and operation of an injection molding system for these alloys can be found in U.S. patent nos. 5,040,589 and 6,494,703.

Fig. 1 and 2 show a known injection molding system 10 including an injection unit 14 and a clamp unit 12 coupled together. The injection unit 14 processes a solid metal feedstock (not shown) into a melt and then injects the melt into a closed and clamped injection mold configured to be in fluid communication therewith. The injection mold is shown in an open configuration in fig. 1 and includes complementary hot and cold halves 23 and 25. The injection unit 14 further includes an injection unit base 28 that slidably supports an injection assembly 29 mounted thereon. The injection assembly 29 includes a barrel assembly 38 configured within the carriage assembly 34, and a drive assembly 36 mounted to the carriage assembly 34. Drive assembly 36 is mounted directly behind tub assembly 38 for operating (i.e., rotating and reciprocating) a screw 56 (fig. 2) disposed within tub assembly 38. The injection assembly 29 is shown connected to the stationary platen 16 of the clamp unit 12 through the use of a cradle cylinder 30. The carrier cylinder 30 is configured to exert a carrier force in operation along the barrel assembly 38 so as to maintain engagement between the machine nozzle 44 (fig. 2) of the barrel assembly 38 and the melt conduits (e.g., sprue bushing, manifold 170, etc.) of the hot half runner system 26 while the melt is injected into the mold (i.e., acting against the reaction force generated by the injection of the melt). The connection between the machine nozzle 44 and the melt conduit of the runner system is preferably a spigot connection as described in U.S. Pat. No. 6,357,511.

The barrel assembly 38 in fig. 2 is shown to include an elongated cylindrical barrel 40 having an axial cylindrical bore 48A configured therethrough. The bore 48A is configured to cooperate with a screw 56 configured therein for machining and transporting the metal feedstock and accumulating and subsequently channeling the melt of molding material during injection of the metal feedstock. The screw 56 includes a helical thread 58 disposed about an elongate cylindrical portion 59 thereof. A rear portion (not shown) of the screw 56 is preferably configured to couple with the drive assembly 36. The forward portion of the screw (also not shown) is configured to receive a non-return valve 60, the operative portion of which is configured forward of the forward facing surface of the screw 56. The barrel assembly 38 also includes a barrel head 42 positioned intermediate the machine nozzle 44 and the forward end of the barrel 40. The barrel head 42 includes a melt channel 48B configured therethrough, the melt channel 48B connecting the barrel bore 48A with a complementary melt channel 48C configured through the machine nozzle 44. The melt channel 48B through the barrel head 42 includes an inwardly tapered portion that transitions the diameter of the melt channel to the much narrower melt of the machine nozzle 44And a channel 48C. The central bore 48A of the barrel 40 is also shown as being comprised of a corrosion resistant material (e.g., Stellite @)^TM) The liner 46 is made to protect a material typically made of a nickel-based alloy (e.g., Inconel)^TM) The resulting barrel substrate material is protected from the corrosive properties of the high temperature metal melt. Other portions of the barrel assembly 38 that come into contact with the molding material melt may also include similar protective liners or coatings.

The barrel 40 is further configured for connection with a source of comminuted metal feedstock through a feed throat (not shown) located through a top rear portion of the barrel (also not shown). The feed throat directs the feedstock into the bore 48A of the barrel 40. The feedstock is then processed into a melt of molding material by its mechanical working, by the action of the screw 56 in cooperation with the barrel bore 48A, and by its controlled heating. Heat is provided by a series of heaters 50 (all of which are not shown), which heaters 50 are arranged along a majority of the length of the barrel assembly 38.

The chucking unit 12 includes: a clamp base 18 having a fixed platen 16 securely held at one end thereof; a clamp block 22 slidably connected at an opposite end of the clamp base 18; and a moving platen 20 configured to translate between the clamp base 18 and the clamp block 22 on a set of tie bars 32, the tie bars 32 additionally interconnecting the fixed platen 16 and the clamp block 22. As is known, the clamping unit 12 further comprises means for moving the platen 20 in impact (not shown) with respect to a stationary platen to open and close the injection mold halves 23, 25 arranged therebetween. Clamping means (not shown) are also provided between the clamping block and the moving platen in order to provide a clamping force between the mold halves 23, 25 during injection of the melt of molding material. The hot half 25 of the injection mold is mounted to a face of the stationary platen 16, while the complementary cold half 23 of the mold is mounted to an opposite face of the moving platen 20.

More specifically, the injection mold includes at least one molding cavity (not shown) formed between complementary molding inserts shared between the mold halves 23, 25. The mold cold half 23 includes a core plate assembly 24 with at least one core molding insert (not shown) configured therein. The mold hot half 25 includes a cavity plate assembly 27 mounted to a face of the runner system 26 with at least one complementary cavity molding insert configured therein. The hot runner system 26 provides a means for connecting the melt channel 48C of the machine nozzle 44 with at least one molding cavity for filling thereof. The runner system 26 includes a manifold plate 64 and a complementary backing plate 62 for surrounding the melt conduits therebetween, and a thermal insulation plate 60. The runner system 26 may be an offset or multi-drop hot runner system, a cold runner system, or any other commonly known melt distribution means.

The process of molding metal in the above system generally comprises the steps of: (i) establishing an inflow of metal feedstock into the rear end portion of barrel 40; (ii) the metal feedstock is processed (i.e., sheared) and heated to form a thixotropic melt of molding material by: (iia) operating (i.e., rotating and retracting) the screw 56, which functions to carry feed/melt along the length of the barrel 40 through the check valve 60, and into the accumulation zone defined forward of the check valve 60, by the screw threads 58 in cooperation with the axial bore 48A; and (iib) heating the feed material as it travels along a substantial portion of barrel assembly 38; (iii) closing and clamping the injection mold halves 23, 25; (iv) the accumulated melt is injected through the machine nozzle 44 and into the injection mold by forward translation of the screw 56; (v) optionally filling any remaining cavities in the molding cavity by applying a continuous injection pressure (i.e., densification); (vi) opening the injection mold once the molded part has solidified by cooling of the injection mold; (vii) removing the molded part from the injection mold; (viii) the injection mold is optionally adjusted for a subsequent molding cycle (e.g., application of a mold release agent).

A major technical challenge impeding the development of hot runner systems 26 suitable for metal injection molding is to provide substantially leak-free means for interconnecting the melt conduits therein. Experience has shown that the conventional connection means used in plastic hot runner systems (i.e., a face seal that is loaded compressively under thermal expansion of the melt conduits) are not suitable for hot runner systems used for metal molding. In particular, in a metallic hot runner system, the degree to which the melt conduits must be compressed in order to maintain a face seal between them is also typically sufficient to crush them (i.e., buckle). This is due in part to the high operating temperatures of the melt conduits (e.g., about 600℃. for typical Mg alloys), which significantly reduces the mechanical properties of the constituent materials (e.g., typically made from hot work tool steels such as DIN 1.2888). Another problem is that the presence of significant thermal gradients in the melt conduits at high operating temperatures contributes to significant unpredictability of their geometry, which complicates the selection of suitable cold clearances.

Another challenge with the structural configuration for the interconnecting melt conduits is to accommodate thermal growth of the interconnecting melt conduits (i.e., when heating the conduits between ambient and operating temperatures) without otherwise moving the functional portions that may need to remain fixed relative to another structure. For example, in a single drop hot runner system (with offset drop) where there are two melt conduits, a supply manifold and a drop manifold respectively, it is advantageous to fix the position of the machine nozzle receptacle portion of the supply manifold for alignment with the machine nozzle 44, while also fixing the drop (i.e., discharge) portion of the drop manifold for alignment with the inlet gate of the molding cavity insert. Therefore, some means for sealing between the supply and drop manifolds must be provided that accommodates the expansion gap between the two in the cooler condition and does not rely on a face seal between the two in the hotter condition. This becomes more challenging in a multi-drop hot runner (i.e., a hot runner with more than one discharge nozzle to serve a larger molding cavity or a mold with more than one molding cavity), where there are many fixed drop portions that are configured on a corresponding number of drop manifolds.

Disclosure of Invention

The present invention provides an injection molding machine apparatus and method to overcome the above-mentioned problems and to provide an effective and efficient means for leak-reducing connections between discrete melt conduits in a molding system.

According to a first aspect of the present invention, structure and/or steps are provided for a molding machine melt conduit coupler including a coupling structure having a first surface configured to couple with a first melt conduit, and a second surface configured to couple with a second melt conduit. The cooling structure is configured to provide a coolant to the coupling structure. Preferably, the cooling structure cools the coupling structure to a temperature that causes any melt that leaks from the coupling structure to at least partially solidify, thereby further sealing the connection.

According to a second aspect of the present invention, sealing structures and/or steps are provided whereby a molding hot runner system includes a plate configured to carry at least one melt-carrying manifold. A coupling is configured to couple the at least one melt-carrying manifold and the melt-carrying passage. A cooling structure is configured to cool the coupling.

According to a third aspect of the present invention, control structure and/or steps are provided for an injection molding machine having a mold configured to form a molten material into a molded article. The first and second molten material conduits are configured to carry molten material to the mold. The molten material conduit coupler is configured to couple the first molten material conduit to the second molten material conduit. The melt conduit coupler includes a coolant passage configured to carry a coolant adapted to remove heat from the molten material conduit coupler.

According to a fourth aspect of the present invention, a method of coupling together first and second molten material conduits includes the steps of: (i) placing an end of the first molten material conduit adjacent to an end of the second molten material conduit; (ii) placing couplers near the ends of the first and second molten material conduits; (iii) positioning a coupler near the ends of the first and second molten material conduits; and (iv) cooling the coupler as molten material flows through the ends of the first and second molten material conduits to cause molten material leaking from the coupler to at least partially solidify.

Drawings

Exemplary embodiments of the presently preferred features of the invention will now be described with reference to the accompanying drawings, in which;

FIG. 1 is a schematic illustration of a known injection molding machine;

FIG. 2 is a partial cross-section of a portion of the injection molding machine of FIG. 1;

FIGS. 3A and 3B include schematic plan and cross-sectional views of a first embodiment in accordance with the present invention;

FIGS. 4A and 4B include perspective and cross-sectional views of an alternative embodiment according to the present invention;

FIG. 5 is a cross section according to another alternative embodiment of the present invention;

FIG. 6 is a perspective view of an embodiment in accordance with the invention for an injection mold hot half;

FIG. 7 is a cross-section of the embodiment of FIG. 6;

FIGS. 8A and 8B include perspective and cross-sectional views of the supply manifold shown in FIGS. 6 and 7;

FIGS. 9A and 9B include perspective and cross-sectional views of the branching manifold shown in FIGS. 6 and 7;

FIG. 10 is a perspective view of another embodiment according to the present invention for an injection mold hot half;

FIG. 11 is a cross-section of the embodiment of FIG. 10;

fig. 12A and 12B include perspective and cross-sectional views of the supply manifold shown in fig. 10 and 11.

Detailed Description

1. Introduction to the design reside in

The present invention will now be described with reference to several embodiments that use an injection molding system to mold a metal alloy (e.g., magnesium) above its solidus temperature (i.e., semi-solid thixotropic or liquid). However, the present invention may be used in other injection molding applications, such as plastic, liquid metal, composites, powder injection molding, and the like.

Briefly, in accordance with the present invention, a melt conduit coupler is provided for interconnecting discrete melt conduits. Preferably, complementary male and female "spigot" coupling portions are respectively configured on each of the melt conduit couplers and along the portions of the melt conduits to be interconnected. As used in this description, a "socket" is a modifier that characterizes the relative configuration of a pair of complementary coupling portions that cooperate to interconnect discrete melt conduits in a substantially leak-free manner. In particular, a complementary pair of "jack" coupling portions is characterized in that the coupling portions are configured to cooperate in an overlapping, closely spaced and mutually parallel relationship. The spigot coupling portions are preferably configured to cooperate to provide a "spigot connection" between each of the melt conduit spigot coupling portions and a complementary spigot coupling portion provided on the melt conduit coupler. A "socket connection" is characterized by the interface between complementary socket coupling portions being cooled. Thus, the spigot connection is provided as a cooling engagement between closely fitting complementary cylindrical sealing surfaces, with oozing or leakage of melt therebetween solidifying to provide a further effective seal that substantially prevents further leakage of melt.

The present invention provides a new use of a spigot connection that solves some of the quite annoying problems in the metal molding runner system outlined above. U.S. Pat. No. 6,357,511 discloses a spigot connection configured between a machine nozzle and a mold sprue bushing. In accordance with the present invention, a melt conduit coupler has been devised that interconnects pairs of melt conduits using a spigot connection. The presently preferred form of the invention is as an interconnection between a pair of melt conduits.

Furthermore, the runner system may also utilize the inventive melt conduit coupler to engage a typical melt distribution manifold contained therein. For example, single drop hot runners in an offset configuration are disclosed herein that are particularly useful for accommodating cold chamber die casting (die casting) molds used in metal injection molding machines. A multi-drop hot runner for use in a metal injection molding machine is also disclosed.

In a preferred embodiment of the present invention, each of the melt conduits includes a spigot coupling portion provided on an outer circumferential surface configured along a cylindrical end portion thereof. Similarly, the melt conduit coupler preferably includes a cooling ring body with a complementary spigot coupling portion disposed along an inner circumferential surface thereof. The ring body is preferably configured for cooling the melt conduit coupler in use to maintain a desired temperature at the spigot connection (i.e. to provide a seal against relatively cooled solidified melt). As an example, when molding with a typical magnesium alloy melt, the temperature of the melt conduit coupler is controlled in use so as to maintain the temperature at the spigot connection at about 350 ℃.

In the following description, the mold operating temperature is generally about 200-230 ℃; the melt temperature is typically about 600 ℃; hot-work tool steel (DIN 1.2888) is preferably used for manifolds, spigot tip inserts and the like. Also, the sealing/cooling rings are preferably made of common tool steel (AISI 4140 or P20) because they are kept at relatively low temperatures and are generally isolated from large forces. Alternatively, where some force transmission is expected, the sealing/cooling ring may be made from AISI H13. The manifold insulator is preferably made of a relatively low thermal conductivity material that is also capable of withstanding extremely high processing temperatures without annealing. Currently, the preferred insulator is made by Inconel^TMAnd (4) preparing. However, the actual mold operating temperature, melt temperature, tool steel, sealing/cooling ring material, and manifold insulation may be selected based on the material being molded, the cycle time required, the materials available, etcAnd (3) a body. All such alternative configurations are intended to be included within the scope of the appended claims.

2. Parameters of socket sealing

According to a preferred embodiment, a melt conduit coupler is provided for interconnecting discrete melt conduits. Thus, spigot coupling portions are arranged on each of the melt conduit couplers and along the melt conduit portions to be interconnected. Preferably, the fit between the complementary socket coupling portions comprises a small diameter gap. The small gap facilitates engagement between complementary coupling portions during assembly. Preferably, the gap is designed to be occupied by the relative expansion of the spigot coupling portion when the melt conduits and the melt coupler are at their operating temperatures. Any diametric interference between the spigot coupling portions at operating temperature can provide a supplemental seal, but is otherwise not dependent on the diametric interference.

In a presently preferred embodiment, a typical gap between the coupling portions is about 0.1mm per side when the melt conduits and the melt conduit coupler are at ambient temperature. However, this 0.1mm gap is not necessary, and the fit between complementary socket coupling portions may otherwise be precise or include slight interference at ambient temperatures. Preferably, each melt conduit coupler is independently temperature controlled.

As will be described in detail below, the temperature at the interface between the spigot coupling portions is preferably controlled with active cooling of the melt conduit coupler so as to maintain a substantially leak-free sealed connection. However, by configuring the melt conduits within the cooled runner system plate (manifold and manifold backing plate maintained at about 200-230℃.), it is also possible to rely solely on passive heat transfer therewith. Preferably, the melt conduit components to be interconnected are arranged in the melt conduit coupler such that a longitudinal cold clearance exists therebetween when the melt conduit components are at ambient temperature. In particular, when the melt conduits are at ambient temperature, there is a cold clearance gap between complementary annular mating faces disposed at the ends of each of the complementary melt conduits.

Preferably, said gap between the mating faces is taken up when the melt conduits are at their operating temperature due to thermal expansion thereof. Thus, the preload, if any, between the mating faces of the melt conduit components can be controlled to avoid excessive compressive forces that could otherwise crush the melt conduit components. In the preferred embodiment, the typical cold clearance of a melt conduit heated to 600 ℃ is about 1 mm. Any face seal provided between the complementary mating faces is complementary at operating temperatures.

3. First embodiment

Referring to fig. 3A and 3B, a first embodiment of the present invention is shown. The first melt conduit 70 and the second melt conduit 70' (containing melt passageways 148B and 148A, respectively) are interconnected by a melt conduit coupler 80. The melt conduit coupler 80 is, in a simple form, an annular body 81 having a coolant channel or channels 82 therein (see fig. 3B). Two coolant fittings 100 are provided for the inlet and outlet of the coolant channels. The coolant channel 82 is preferably connected to a source of coolant (typically air) that maintains the temperature of the melt conduit coupler 80 at about 350 ℃. However, other coolants such as oil, water, gas, etc. may be used depending on the molding application. It should be noted that 350 ℃ is relatively cool compared to melt conduits that are typically maintained at about 600 ℃ for magnesium alloy molding.

The melt conduit coupler 80 is also shown to include a thermocouple arrangement 86 including a bore configured for receiving a thermocouple. Adjacent to the thermocouple device is a thermocouple retainer 88 which includes an aperture configured to receive a fastener which, in use, retains a clamp (not shown) which retains the thermocouple within the thermocouple device 86. Preferably, the thermocouple arrangement 86 is positioned in close proximity to the spigot coupling portion 76 'disposed about the inner circumferential surface of the melt conduit coupler 80 so that the temperature at the spigot connection with the complementary spigot coupling portion 76 disposed about the end portion of the melt conduit 70, 70' can be controlled. Each of the melt conduits 70, 70' may have a heater 50 in order to maintain the temperature in the melt in the conduit at a prescribed operating temperature, which is also about 600 ℃ for magnesium alloy molding.

Fig. 3B shows a schematic cross-section of a melt conduit coupler 80. The preferred embodiment uses a spigot connection between the melt conduit coupler 80 and the end portions of the melt conduits 70, 70'. Preferably, the inner circumferential surface of the annular body 81 and the outer circumferential surface of the end portion of the melt conduits 70, 70 'to be interconnected are given a complementary configuration, wherein the position of the melt conduit coupler 80 is substantially fixed near the interface between the melt conduits 70, 70'. Thus, complementary shoulders are provided around the outer circumferential surfaces at the end portions of the melt conduits 70, 70' and around the inner circumferential surface of the melt conduit coupler 80, respectively. The melt conduit coupler 80 is configured to include a pair of shoulders, one for each of the melt conduits 70, 70' to be interconnected, and the shoulders are configured at opposite ends of the inner circumferential surface of the melt conduit coupler 80, the shoulders being separated by a residual annular portion 92. Complementary spigot coupling portions 76, 76 'are provided on the melt conduit couplers 70, 70' and the melt conduit coupler 80, respectively, on the outer circumferential surface of the recessed portion of the shoulder and on the inner circumferential surface of the annular portion 92. Of course, depending on the molding application, the coupling may exclude complementary shoulders, or may incorporate any number and/or shape of convex and concave surfaces to enhance coupling.

As described above, the socket coupling portions 76, 76' are preferably configured to have a small gap therebetween. In use, a 600 ℃ magnesium alloy has a viscosity similar to water, and is therefore generally able to seep between the complementary mating faces 120, 120 ' of the melt conduits 70, 70 ', and then between the spigot coupling portions 76, 76 '. However, because the melt conduit coupler 80 is maintained at a relatively low temperature (i.e., about 350 ℃) by active or passive cooling, the melt will solidify, completely or at least partially, in these gaps and provide a seal that substantially prevents further leakage of melt.

A thermocouple 74 may be disposed at an end portion of either or both of the melt conduits 70, 70' to detect the temperature of the melt conduit adjacent to the melt conduit coupler 80. Preferably, the thermocouple 74 is positioned very close to the interface between the spigot coupling portions 76, 76 'so that the temperature of the melt within the melt channels 148A, 148B adjacent the spigot connections can be controlled (e.g., by controlling the power to the heater 50 disposed near the melt conduits 70, 70') so as to prevent the formation of a plug (plug) in the melt channels 148A, 148B adjacent the cooling spigot connections.

The mating faces 120, 120 'of the melt conduits 70 and 70' are shown to preferably include a longitudinal cold clearance gap 116 of about 1mm therebetween when the melt conduits are at the ambient temperature. This gap is selectively (predetermined) occupied (or substantially closed) as the melt conduits expand in length as they are heated to operating temperatures. Thus, there is substantially no gap, or even some degree of compression, possible between the mating faces of the melt conduits 70 and 70'. Any such compression may be used to provide a supplemental seal against leakage of melt. In this manner, excessive compressive forces between the melt conduits 70, 70 'due to thermal expansion that may otherwise cause local bending in the melt conduits 70, 70' are substantially avoided.

As noted above, the melt also has a way to travel through the gap between the spigot coupling surfaces 76, 76 'and is substantially prevented only by carefully controlling the temperature at the interface between these spigot coupling portions 76, 76' well below the melting point of the molding material. For the preferred embodiment, a cold clearance of about 0.1mm between the spigot coupling portions 76, 76' is preferably provided at ambient temperature. In use, the relative thermal expansion of the melt conduit coupler 80 and the melt conduits 70, 70' is such that this diametric gap will be substantially occupied, and preferably, there is intimate contact between the accompanying parts at operating temperatures. This intimate contact will provide a supplemental seal that prevents further leakage of melt, although a small residual gap may be tolerated in view of the primary sealing mode (i.e., sealing of the solidified melt). Alternatively, there may be an exact fit or even a small compressive preload between the spigot coupling portions 76, 76' at ambient temperature. This will ensure that at operating temperatures there is a supplemental seal due to compression between the spigot coupling portions 76, 76'. Thus, the melt coupler 80 of the present invention provides a substantially leak-free seal between the melt conduits 70, 70 ', which functions without the need for compressive sealing forces between the mating faces 120, 120 ' of the melt conduits 70, 70 '.

In an alternative embodiment (not shown), the melt conduit coupler may be integrated onto one end of one of the melt conduits.

In an alternative embodiment, as shown with reference to fig. 4A and 4B, the melt conduit coupler 180 is a parallelepiped. Thus, the outer surface of the melt conduit coupler 180 is rectangular and the central cylindrical channel configured therethrough is configured in a manner consistent with the previous embodiments with reference to fig. 3A and 3B. The rectangular body 181 of the melt conduit coupler 180 is easier to integrate (i.e., secure) within a plate of a hot runner system, as shown with reference to fig. 6 and 10. Preferably, the rectangular body 181 is configured to be secured in a complementarily shaped pocket provided in the hot runner plate (e.g., referring to fig. 7, the hot runner plate includes a manifold plate 64 or backing plate 62). As will be explained in detail below, the hot runner plate provides a housing for the melt conduits 70, 70' (or more commonly known as a "manifold"), the melt conduit coupler 80, and all other related components.

As previously mentioned, the particular features of the melt conduit coupler 180 are substantially similar to those discussed above with reference to the melt conduit coupler 80 in fig. 3A and 3B. Spigot coupling portions 76' are provided on an inner circumferential surface of the annular portion 192, and also provide shoulders, disposed on each side of the annular portion 192, that cooperate, in use, with complementary shoulders disposed on the melt conduit or manifold to substantially secure the melt conduit coupler 180. The coolant channel 182 preferably includes various drilled portions, so there is a first coolant channel portion 182A, a second coolant channel portion 182B, a third coolant channel portion 182C, and a fourth coolant channel portion 182D. Preferably, the coolant channel portion is formed by drilling and the drilling access may be plugged with a plug 182 as desired. Coolant ports 184 and 184' are provided in communication with coolant passage 182 for receiving coupling fitting 100. As before, a thermocouple may be installed within the thermocouple arrangement 186 proximate the complementary spigot coupling portion 76' so that the temperature of the spigot connection can be closely monitored and the temperature and/or flow of coolant can be adjusted accordingly. Preferably, by using a Thermolator as required^TMThe heating/cooling unit regulates the coolant outside the mold. Likewise, the thermocouple retainer 88 is provided adjacent the thermocouple assembly 186 to accommodate fasteners that fasten a clamp (not shown) for securing the thermocouple within the thermocouple assembly 186.

Also shown in FIG. 4A are a pair of cylindrical bores 194, the cylindrical bores 194 being configured on either side of a central opening in the melt conduit coupler 80 and substantially perpendicular to the axis thereof. In addition, a cut-out portion (cut-out)196 is disposed at a first end of each of the cylindrical holes 194 on one end of the rectangular body 181. The cylindrical bore 194 and the cutout 196 provide a structure that cooperates with the shank and head, respectively, of a fastener (e.g., a socket head cap screw) so that the melt conduit coupler 180 may be secured within a pocket provided in a hot runner plate (e.g., see the manifold plate 64 of fig. 7).

Also shown in fig. 4A is a pocket surface 198 on each face 199 of the melt conduit coupler 180. The face 199 contacts the surface of the pocket within the hot runner plate and controls the amount of heat transfer therebetween. The larger the contact surface between the face 199 of the melt conduit coupler 180 and the pocket, the more heat transfer there between. Accordingly, the preferred design minimizes the contact surface between the face 199 and the pocket in the hot runner plate using the pocket surface 198 so that the temperature at the spigot coupling portion 76, 76' can be more precisely controlled by the influence of the coolant flow within the coolant channel 182.

4. Supplemental expansion liner

Referring to FIG. 5, an alternative embodiment of the present invention is shown. The same structures as those shown in fig. 3B are denoted by the same reference numerals. In fig. 5, an expansion bushing 93 is provided to provide a supplemental seal between the melt conduits 70, 70'. Preferably, the expansion bushing is provided by an annular ring (annular ring). The outer circumferential surface of the annular ring is configured to cooperate with a bushing seat 78 provided along the inner circumferential surface of a cylindrical bore formed through the end portion of the melt conduits 70, 70', concentric with the melt channels 148A and 148B. The inner circumferential surface of the expansion bushing connects the melt channels 148A and 148B and preferably has the same diameter. Preferably, the supplemental expansion bushing 93 is made of a metal different from the material of the melt conduits whereby a compressive sealing force is formed between the outer surface of the expansion bushing 93 and the bushing seat 78 due to the relative thermal expansion of the expansion bushing 93 and the melt conduits 70, 70'. Preferably, the supplemental expansion bushing 93 is made of, for example, Stellite^TM(cobalt-based alloys) that will grow slightly more per given temperature change than a melt conduit that can be made from DIN 1.2888. Since the bushing seat 78 will also expand in length, a longitudinal cold clearance gap is preferably provided between the end of the expansion bushing and the corresponding end of the seat to the extent that a portion of the gap remains even when the melt conduits 70, 70 'are at their operating temperature, so that the expansion bushing 93 does not function to separate the melt conduits 70, 70'.

5. Use in offset applications

Referring to fig. 6 and 7, the injection mold hot half 25 is shown as including a single drop hot runner 26 (with offset drops) and a cavity plate assembly 27. The hot half 25 is preferably configured to accommodate a cavity molding insert (not shown). The hot runner 26 is useful for accommodating molds intended for use in cold chamber die casting machines used in injection molding machines. In particular, many such molds include an offset injection portion (not shown) that is otherwise required to prevent the melt from freely flowing into the mold cavity during an initial "slow shot" that purges air from the cold chamber. Thus, to position the cavity in the center of the die-casting machine, the injection point is positioned offset from the center of the mold. Also, it may be necessary to offset the injection point for the parts that have to be filled from the outside to the inside. The hot runner includes a backing plate 62 and a manifold plate 64, between which melt conduit components and other ancillary components are housed. The hot runner 26 includes two melt conduits, a supply manifold 170 and a drop manifold 172. Both the supply and drop manifolds 170, 172 are configured to include right angle melt channels therein, as shown in detail in fig. 8A, 8B, 9A and 9B.

The supply and drop manifolds 170 and 172 are preferably interconnected with a melt conduit coupler 180. Preferably, the manifold itself is positioned in a manifold pocket 65 provided in the manifold plate 64, and as shown with reference to fig. 7. The manifolds 170, 172 are also configured to receive the side insulator 106 and the axial insulators 108 and 114, which substantially isolate the heated manifolds from the relatively cooler plates and transfer axial loads thereto. Also shown in FIG. 6 is a coolant conduit 104 that is configured to connect with coolant ports 184, 184' on the melt conduit coupler 180. Also shown in backing plate 62 is a maintenance box 63 that provides clearance for portions of manifolds 170, 172, thermocouple and heater wiring, coolant conduits and other ancillary components.

Also shown in FIG. 6 is a cooling ring 185 that cools the inlet portion of the supply manifold 170. The cooled inlet portion will help establish a spigot connection between the spigot coupling portion 174 of the nozzle block configured to pass through the inlet portion of the supply manifold 172 and the complementary spigot portion 45 provided on the machine nozzle 44, and described in detail below. This configuration is generally known with reference to U.S. patent No. 6,357,511. The cooling ring 185 includes an annular coupling body having a coolant passage disposed therein.

Also shown in FIG. 6 is a mold positioning ring 54 configured to cooperate with a complementary positioning ring (not shown) provided in the stationary platen 16 (FIG. 1) of the injection molding machine clamp 12 (FIG. 1) to align the nozzle seat of the supply manifold 170 with the machine nozzle 44 (FIG. 2). The cavity plate assembly 27 more specifically includes a cavity plate 66 and a partition plate 68. A cavity molding insert (not shown) may be connected to the front face of the cavity plate 66. Also provided in the cavity plate 66 is a modified mold cold gate 150 comprising a gate bushing 151 with an outwardly tapered gate channel 153 in the gate bushing 151 configured for discharging melt therethrough. The mold cold gate 150 may additionally be a branch nozzle assembly 250, as will be explained later with reference to the embodiment of FIG. 10. The spacer plate 68 is simply an intermediate plate that spans the gap between the hot runner 26 and the cavity plate 66, which is otherwise dictated by the length of the discharge portion (e.g., elbow segment 308 as shown with reference to fig. 9A and 9B). The length of the discharge portion is established to ensure its versatility for use with branch nozzle assemblies 250 (fig. 11). Preferably, the manifold plate 64 is provided with a branch passage 67, and the discharge portion of the branch manifold 172 extends through the branch passage 67.

Referring to fig. 8A and 8B, the supply manifold 170 is shown in more detail. The supply manifold 170 preferably has a cross-like shape and includes four structural portions: a first elbow portion 206, a second elbow portion 208, a third elbow portion 210, and a fourth elbow portion 212. Each of the elbows 206, 208, 210, and 212 is configured to perform a unique function. The first elbow portion 206 is essentially an inlet portion configured for interconnection with the machine nozzle 44, connecting, in use, the machine nozzle melt channel 48C with the melt channel 148A of the first elbow portion 206. The first and second elbow portions 206, 208 are configured to be substantially perpendicular to each other. Thus, the second elbow portion 208 includes a melt channel 148B extending therealong, the melt channel 148B being configured to cooperate with the melt channel 148A of the first elbow portion 206 to substantially redirect melt traveling therethrough. The second elbow portion 208 is further configured for interconnection with an adjacent drop manifold 172 through the use of the melt conduit coupler 80. The third elbow portion 210, which is generally aligned with the first elbow portion 206, is configured for positioning the supply manifold 170 within the plates 62, 64 along the first axis and for transferring loads thereto. A fourth elbow portion 212, generally perpendicular to the third elbow portion 210 and generally aligned with the second elbow portion 208, is also configured for positioning the supply manifold 170 within the plates 62, 64 along the second axis, and also for transferring loads thereto. Each of the elbows is preferably configured as a substantially cylindrical body.

Referring to FIG. 8B, the first elbow portion 206 includes a melt channel 148A extending from the free end of the first elbow portion 206 along the length of the first elbow portion, wherein the melt channel 148A is interconnected with the melt channel 148B provided along the second elbow portion 208. At the free end of the first elbow portion 206 there is also provided a shallow cylindrical bore which provides a seat for receiving the spigot tip of the machine nozzle 44. Thus, the inner circumferential surface of the seat provides a socket mating portion 174. Preferably, a gap is provided between the shoulder 175 at the base of the seat and the front face of the socket portion 45 when the socket portion 45 is fully engaged within the seat. Thus, the annular face 218 provided at the free end of the first elbow portion 206 provides a spigot mating face 218 that is configured to cooperate with a complementary mating face provided on the machine nozzle 44, limiting longitudinal engagement of the spigot portion 45 of the machine nozzle 44 into the seat, and may additionally provide a supplemental face seal to prevent leakage of melt of molding material. Also shown is a seat configured along a shallow diameter groove provided in the outer circumferential surface of the first elbow portion 206 and directly adjacent the free end of the first elbow portion 206 for receiving the cooling ring 185. As previously described, the cooling ring 185 functions to cool the interface between the spigot coupling portion 174 of the seat, thereby providing a spigot seal with a complementary spigot coupling surface on the spigot portion 45 of the machine nozzle 44.

The cooling ring seat comprises a mating portion 200 and a locating shoulder 201. The mating portion 200 preferably cooperates with a complementary mating portion provided on the cooling ring 185 for conducting heat between the supply manifold and the cooling ring for cooling the spigot coupling portion 174. Preferably, the locating shoulder 201 secures the cooling ring 185 adjacent the free end of the first elbow portion 206.

A cooling ring 185 is shown in fig. 6 and 7. It preferably comprises an annular body in which the coolant passages are arranged. The coolant passageway is coupled to a source of coolant in the same manner as the melt conduit coupler 80 described above. The cooling ring is configured to cool the free end of the supply manifold 170 to ensure that the interface between the spigot tip 45 of the machine nozzle 44 and the spigot coupling portion 174 in the supply manifold is maintained at or below the melting temperature of the melt so as to provide a seal of mold hardened or semi-hardened melt material therebetween.

The remaining outer circumferential surface of the first elbow portion 206 is configured to receive the heater 50. The heater maintains the temperature of the melt in the melt channel 148A at a prescribed operating temperature. A controller (not shown) controls the heater 50 through feedback from one or more thermocouples located in the thermocouple installation cavity 186 and monitoring the temperature of the melt channel 148A. Feedback from the thermocouple may also be used to control the temperature in the cooling loop 185. A thermocouple clamp retainer 188 may be used to retain one or more of the thermocouples in their respective thermocouple installation cavities 186.

The second elbow portion 208 is generally perpendicular to the first elbow portion and also includes a melt channel 148B that extends through a free end of the second elbow portion and interconnects with the melt channel 148A of the first elbow portion at a generally right angle thereto. An annular flat front face at the free end of the second elbow portion 208 provides a mating space 220 configured to cooperate with a complementary mating face on the drop manifold 172, as will be described below. Also shown in the outer surface of the second elbow portion 208 is a shallow diameter groove that provides a seat for receiving the melt conduit coupler 180.

More specifically, the melt conduit coupler seat comprises: a socket coupling portion 76 provided along an outer circumferential surface of the groove portion; and a locating shoulder 79 securing the melt conduit coupler adjacent the free end of the second elbow portion 208. Like the first elbow portion 206, the second elbow portion 208 is configured to receive a heater 50, the heater 50 for maintaining the temperature of the melt within the melt channel 148B at a prescribed operating temperature. Also, a thermocouple installation cavity is preferably provided along the second elbow portion 208 for providing temperature feedback to the heater controller and the temperature controller of the melt conduit coupler 180.

The third elbow portion 210 is also preferably substantially perpendicular to the second elbow portion 208 and substantially coaxial with the first elbow portion 206. The third elbow portion 210 includes a shallow cylindrical bore that provides a seat 214 configured for receiving the axial insulator 108 (shown in fig. 7). The axial insulator 108 functions to thermally isolate the supply manifold 172 from the cold manifold plate 64. The axial insulator 108 is also configured to help position the supply manifold 172 generally on the first axis and is also configured to direct longitudinally applied compressive forces from the machine nozzle into the manifold plate 62. Thus, the axial insulator is preferably designed to withstand the separating forces due to melt pressure and the carriage forces formed by the carriage cylinder. The third elbow portion 210 is preferably heated by a heater 50 located on its outer surface to compensate for heat lost to the cooled manifold plate 62.

The fourth elbow portion 212 is also substantially perpendicular to the third elbow portion 210 and is substantially coaxial with the second elbow portion 208. The fourth elbow portion 212 includes an insulator table 216 configured on an end face of a free end of the fourth elbow portion and including substantially parallel side walls configured to cooperate with a complementary slot and side insulator 106 (as shown in fig. 7). The side insulator 106 is also configured to cooperate with a complementary seat provided in the manifold plate 64 to help locate and thermally isolate the supply manifold 170. The fourth elbow portion 212 is preferably heated by a heater 50 located on its outer surface to compensate for heat lost to the cooled manifold plate 62.

As introduced above, the position of the first elbow portion 206 (i.e., the inlet portion) of the supply manifold 170 is preferably substantially fixed relative to the first axis. Referring to fig. 7, it can be seen that the position of the supply manifold 170 is substantially fixed along a first axis between the cooling ring 185 and the axial insulator 108, the cooling ring 185 and the axial insulator 108 themselves being located within seats provided in the backing plate 62 and in the manifold plate 64, respectively. Preferably, a cylindrical bore is provided through the backing plate 62, which provides a passage 59, the passage 59 providing clearance for the machine nozzle 44 and the first elbow portion 206 of the supply manifold 170. In addition, the inner circumferential surface of the passage 59 provides a cooling ring seat 204 that locates the cooling ring 185 and thereby the first elbow portion 206 of the supply manifold 170. Similarly, in the manifold plate 64 is a shallow cylindrical bore that provides an insulator pocket 69 and provides clearance for the third elbow portion 210 of the supply manifold 170. Preferably, there is another shallow cylindrical bore concentric with the insulator pocket 69, the insulator pocket 69 providing a seat 114 for receiving the axial insulator 108. The axial insulator 108 is preferably secured or retained into the insulator seat 114, and the insulator seat (in cooperation with a complementary insulator seat in the third elbow portion) generally locates the third elbow portion 206 of the supply manifold.

In fig. 7, the side insulator 106 is shown mounted in an insulator seat 114 provided in the manifold plate 64 directly adjacent to the manifold pocket 65. The side insulator 106 is further configured to cooperate with the insulator table 216 on the fourth elbow portion 212 to preferably thermally isolate the supply manifold 170 from the cooled manifold plate 64 to resist, in use, any separating forces between the supply manifold 170 and the drop manifold 172 (e.g., reaction forces from melt flow within the melt channel 148B), and thereby provide a limited degree of alignment for the supply manifold 170.

The drop manifold 172 is shown in fig. 9A and 9B. The drop manifold 172 is configured very similar to the supply manifold 170 and has a cross-like configuration similar to the first, second, third and fourth elbow portions 306, 308, 310 and 312, respectively. The first elbow portion 306 is configured to be coupled to the second elbow portion 208 of the supply manifold 170.

Thus, the first elbow portion 306 includes a melt channel 148C that extends through the free end of the first elbow portion 306 and along the length of the first elbow portion 306, and interconnects with a melt channel 148D that extends along the second elbow portion 308. As with the second elbow portion 208 of the supply manifold, the first elbow portion 306 of the drop manifold includes a diametric notched portion adjacent to the free end that provides a seat for the melt conduit coupler 180. As previously explained, the seat preferably includes a socket coupling portion 76 and a locating shoulder 79. An annular flat face at the free end of the first elbow portion 306 provides a mating face 220 that cooperates with a complementary mating face on the supply manifold 170. The remaining outer portion of the first elbow portion 306 is configured to accommodate the heater 50 and one or more thermocouple devices 186, as previously explained.

The second elbow portion 308 or discharge portion is generally perpendicular to the first elbow portion 306. The second elbow portion 308 includes a melt channel 148D extending through a free end of the second elbow portion 308 and interconnected with the melt channel 148C of the first elbow portion 306. The free end of the second elbow portion 308 is preferably configured to include a seat for receiving a socket tip insert 145. Of course, the spigot tip insert may additionally be manufactured integrally with the second elbow portion, as shown with reference to fig. 11, wherein an alternative embodiment of the drop manifolds 172 and 172' is shown. As shown in fig. 7, this spigot tip insert 145 is configured to interconnect the drop manifold 172 with the sprue bushing 151 of the cold sprue 150. The seat provided through the free end of the second elbow portion 308 is provided by a shallow cylindrical bore, and the inner circumferential surface of the shallow bore provides a socket coupling surface 176, said socket coupling surface 176 cooperating with an outer circumferential complementary socket coupling portion 176' on the socket tip insert 145. Also, an annular shoulder provided at the base of the shallow cylindrical bore provides a locating shoulder 177 for locating the spigot tip insert 145 within the socket. The outer circumferential surface of the spigot tip insert 145 also provides a spigot coupling portion 147 that is configured so as to cooperate with a complementary spigot coupling portion 147' provided in the sprue bushing 151. By thermal conduction to the cooled cavity plate assembly 66, a socket seal is maintained between the complementary socket interface portions 147, 147 'and between the socket coupling portions 176, 176'. The remaining outer surface of the second elbow portion 308 is preferably configured for housing the heater 50, and includes one or more thermocouple device cavities 186 for temperature feedback control of the heater 50, as previously explained.

The third elbow portion 310 is configured similarly to the fourth elbow portion 212 of the supply manifold 170, and thus includes an insulator table 216 for receiving the side insulator 106, as shown in fig. 7. The side insulator 106 is shown mounted in an insulator seat 114 provided in the manifold plate 64.

The fourth elbow portion 312 is configured similarly to the third elbow portion 210 of the supply manifold 170, and thus includes an insulator seat 214. The insulator seat 214 is preferably configured to receive one end of the axial insulator 110 seen in fig. 7. The axial insulator 110 is secured within an insulator seat 114 provided in the backing plate 62. Also shown is the backing plate 62 configured with a shallow cylindrical bore therein that provides an insulator pocket 69 for providing clearance around the fourth elbow portion 312 of the drop manifold 172. The insulator seat 114 is preferably configured as a concentric shallow cylindrical bore formed at the base of the insulator pocket 69. As before, the axial insulator 110 functions to thermally isolate the drop manifold 172 from the backing plate 62, transfer axial loads to the manifold plate 62, and help position the drop manifold 172 near the entrance of the cold gate 150. In particular, with reference to FIG. 7, it can be seen that the position of drop manifold 172 is substantially fixed along a first axis between a gate bushing 151 and axial insulator 110, with gate bushing 151 and axial insulator 110 themselves seated within seats provided in cavity plate 66 and backing plate 62, respectively.

As also shown in fig. 7, the melt conduit coupler 180 is located within a seat 178 provided in the manifold plate 64. As previously described, the melt conduit coupler 180 is preferably secured within the seat 178 through the use of fasteners that pass through cylindrical bores 194 in the melt conduit coupler 180 and cooperate with complementary portions in the manifold plate 64.

As previously explained with reference to fig. 3A, 3B and 5, the spigot coupling portion 76 provided on the inner circumferential surface of the melt conduit coupler cooperates with complementary spigot coupling portions 76' of the free ends of the supply and drop manifolds 76 to provide a spigot seal therebetween. In cold conditions, there is preferably a cold clearance gap 116 between the drop manifold 172 and the mating face 220 of the supply manifold 70. At operating temperatures, however, due to thermal growth of the manifolds, the mating faces of the manifolds will preferably meet to provide a supplemental face seal therebetween.

Also shown in fig. 7 is an optional insulating plate 60 that thermally isolates the hot runner 26 from the relatively cool stationary platen 16 (fig. 1) of the machine clamp 12.

Referring to fig. 10 and 11, another embodiment according to the present invention is shown. In particular, the hot half 25 is configured to include a multi-drop hot runner 26. The branches of the multi-branch hot runner 26 may be used to service larger molding cavities or multi-cavity molds. Although the present invention is configured to include two vertically oriented branches, other numbers and configurations of branches may be utilized. In the present embodiment, the mold insert is not shown, but would otherwise be mounted to the front face of the cavity plate assembly 27, or recessed therein. The cavity plate assembly 27 has been configured to include two mold drop nozzle assemblies 250, each configured to couple a molding cavity (not shown) with the drop manifolds 172 and 172'. The structure and operation of such a branch nozzle assembly 250 is described generally with reference to the description of the gating apparatus in pending PCT application PCT/CA 03/00303. An important difference is that the drop nozzle assembly 250 is currently configured so as to be coupled with the drop manifold 172 rather than the machine nozzle 44.

As shown with reference to fig. 11, the drop nozzle assembly 250 includes a sprue bushing 252, which is essentially a tubular melt conduit that is received between the forward housing 250 and the cooling insert 256.

The sprue bushing 252 is disposed within the front housing 254 such that a spigot ring portion 288 disposed forward of the sprue bushing 252 is received within a complementary spigot coupling portion provided in a front portion 290 of the front housing 254. The rear portion of sprue bushing 252 is received within a cooling insert 256 located within the rear portion of a front housing 254. The cooling insert 256 functions to cool the inlet portion of the sprue bushing 252 so that a spigot connection can be maintained between the spigot coupling portion 174 (configured along an inner circumferential surface of a shallow cylindrical bore formed through an end of the sprue bushing 252) and a complementary spigot coupling portion disposed on the drop manifold 172.

Also shown are a plurality of heaters arranged along the length of sprue bushing 252 so as to maintain the temperature of the melt within the melt channel therein at a prescribed operating temperature.

The configuration of the supply 270 and drop manifolds 172, 172' shown configured between the manifold plate 64 and the manifold backing plate 62 with reference to fig. 7 is substantially the same as that described with reference to the hot runner configuration (fig. 7). As shown with reference to fig. 12A and 12B, a significant difference with respect to the supply manifold 270 (with respect to that previously described and shown in fig. 8A and 8B) is that the fourth elbow portion 412 has been configured the same as the second elbow portion 408 (including the additional melt channel 148B ') and, thus, is configured for interconnection with the additional drop manifold 172' adjacent thereto. To accommodate the additional drop manifold 172', as shown in FIG. 11, additional melt conduit couplers 180, drop channels 67, insulator pockets 69, and insulator arrangements 114 are provided.

As noted above, the hot runner 26 may be reconfigured to include any number and/or configuration of branches. Thus, many variations in the number and configuration of manifolds are possible. For example, an intermediate manifold (not shown) may be configured between the supply and branch manifolds.

Any type of controller or processor may be used to control the temperature of the melt and structures, as described above. For example, one or more general purpose computers, Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), gate arrays, analog circuits, dedicated digital and/or analog processors, hardwired circuits, etc., may receive inputs from the thermocouples described herein. Instructions for controlling one or more of such controllers or processors may be stored in any desired computer readable medium and/or data structure, such as a floppy disk, a hard drive, a CD-ROM, a RAM, an EEPROM, a magnetic medium, an optical medium, a magneto-optical medium, etc.

6. Conclusion

Thus, what has been described is a method and apparatus for coupling molding machine structures so as to provide enhanced sealing while allowing for thermal expansion of the components.

The individual components shown in outline or designated by blocks in the attached drawings are all well-known in the injection molding arts, and their specific construction and operation are not critical to the operation or best mode for carrying out the invention.

While the invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (38)

1. A molding machine melt conduit coupler, comprising:

coupling structure having at least one surface configured to couple with a first melt conduit, the at least one surface also configured to couple with a second melt conduit; and

a cooling structure configured to provide a coolant to the coupling structure.

2. The melt conduit coupler of claim 1, wherein the cooling structure comprises at least one coolant passage disposed within the coupling structure.

3. The melt conduit coupler of claim 2, wherein the coolant passageway comprises a plurality of substantially straight channels disposed between the first surface and the second surface.

4. The melt conduit coupler of claim 3, further comprising at least one coolant passage fitting coupled to at least one of the channels and configured to supply a coolant to the coolant passage.

5. The melt conduit coupler of claim 1, further comprising at least one thermocouple device cavity disposed in the coupling structure.

6. The melt conduit coupler of claim 1, wherein the coupling structure first surface is configured to couple with a branch manifold, and wherein the coupling structure second surface is configured to couple with a supply manifold.

7. The melt conduit coupler of claim 1, wherein said coupling structure comprises a spigot coupling portion having an inner surface with complementary coupling structures therein configured to mate with said first melt conduit and said second melt conduit.

8. The melt conduit coupler of claim 1, further comprising an expansion bushing disposed adjacent to inner surfaces of the first melt conduit and the second melt conduit, a thermal expansion characteristic of the expansion bushing being greater than a thermal expansion characteristic of the first melt conduit and the second melt conduit.

9. The melt conduit coupler of claim 1, wherein the coupling structure is integrally formed on the first melt conduit.

10. A mold hot-runner system, comprising:

a plate configured to carry at least one melt-carrying manifold; and

a coupling configured to couple the at least one melt-carrying manifold and a melt-carrying passage;

and

a cooling structure configured to cool the coupling.

11. A mold hot runner system according to claim 10 wherein said at least one melt-carrying manifold comprises a drop manifold, and wherein said melt-carrying passage comprises a supply manifold.

12. A mold hot-runner system according to claim 11, wherein the cooling structure is configured to cool the coupling to a temperature that causes melt leaking from at least one of: (i) the coupling, (ii) the branching manifold, and (iii) the supply manifold.

13. A mold hot runner system according to claim 11 wherein the cooling structure is configured to cool the coupling to a temperature that causes melt to solidify to a degree that provides a seal for the leaking melt.

14. The mold hot-runner system of claim 11, wherein each of the drop manifold and supply manifold has one input and a plurality of outputs.

15. The mold hot-runner system of claim 10, wherein the cooling structure comprises:

a rectangular body;

a coolant passage disposed in the rectangular body; and

at least one coolant fitting coupled to the coolant passage.

16. The mold hot-runner system of claim 15, wherein the cooling structure further comprises at least one molding surface configured to mate with a complementary molding surface on an adjoining mold member.

17. A mold hot runner system according to claim 10 wherein said coupling comprises a spigot coupling portion having an inner surface with complementary coupling structures therein configured to mate with said at least one melt-carrying manifold and said melt-carrying passage.

18. The mold hot runner system of claim 10, wherein the at least one melt-carrying manifold comprises a plurality of drop manifolds.

19. The mold hot-runner system of claim 10, wherein the at least one melt-carrying manifold comprises a drop manifold, and wherein the melt-carrying passage comprises a supply manifold, and further comprising at least one intermediate manifold disposed between the supply manifold and the drop manifold.

20. A mold hot runner system according to claim 10 further comprising an expansion bushing disposed adjacent to the inner surfaces of the at least one melt-carrying manifold and the melt-carrying passage, a thermal expansion characteristic of the expansion bushing being greater than a thermal expansion characteristic of the at least one melt-carrying manifold and the melt-carrying passage.

21. The melt conduit coupler of claim 10, wherein the coupling is integrally formed on at least one of the at least one melt-carrying manifold and the melt-carrying passage.

22. The melt conduit coupler of claim 10, wherein the coupling is formed on an end of the at least melt-carrying manifold.

23. An injection molding machine, comprising:

a mold configured to form a molding material melt into a molded article;

first and second melt conduits configured to carry the melt of molding material to the mold; and a melt conduit spigot coupler configured to couple the first melt conduit to the second melt conduit, the melt conduit spigot coupler including a coolant passage configured to carry a coolant adapted to remove heat from the melt conduit spigot coupler.

24. An injection molding machine according to claim 23, wherein the mold includes a hot runner half, wherein the melt of molding material comprises a metallic alloy, and wherein the melt conduit coupler is configured to provide a cold clearance gap between the first melt conduit and the second melt conduit.

25. The injection molding machine according to claim 23, wherein the first melt conduit comprises a drop manifold, and wherein the second melt conduit comprises a supply manifold.

26. Apparatus for coupling first and second molding machine conduits adapted to carry a metal melt, said apparatus comprising:

a coupling device having a surface configured to provide a spigot coupling portion that cooperates with a complementary spigot coupling portion configured on an end of each of the first conduits and an end of the second conduit and positions the ends of the first and second conduits such that the metal melt will flow from the first conduit to the second conduit; and

a cooling structure disposed relative to the coupling arrangement to cause at least partial solidification of leaked metal melt between the spigot coupling portions so as to at least partially seal the leaked metal melt.

27. The apparatus of claim 26, wherein the cooling structure comprises a coolant passage disposed within the coupling device.

28. The apparatus of claim 27, wherein the coupling means comprises:

a main body having a circular hole therein;

a socket coupling portion disposed on an inner circumferential surface of the circular hole;

at least one thermocouple device cavity disposed proximate to the spigot coupling portion; and

at least one coolant fitting coupled to the coolant passage.

29. The apparatus of claim 28, wherein the body has first and second molding surfaces configured to contact first and second complementary mold faces, respectively.

30. A single drop hot runner with an offset drop, comprising:

a first molding material conduit having at least one elbow portion;

a second molding material conduit having at least one elbow portion; and

a cooling coupler configured to couple together the at least one elbow portion of the first molding material conduit and the at least one elbow portion of the second molding material conduit, the cooling coupler having at least one coolant passage configured to remove heat from the cooling coupler, wherein the cooling coupler comprises a spigot connection.

31. A multi-drop hot runner, comprising:

a first molding material conduit having an inlet and first and second outlets;

a second molding material conduit coupled to the first molding material conduit first outlet;

a third molding material conduit coupled to the first molding material conduit second outlet;

a first cooling coupler configured to couple the second molding material conduit with the first molding material conduit first outlet, the first cooling coupler having cooling structure to remove heat from the first cooling coupler to cause molten material leaking between the first cooling coupler and the second molding material conduit and the first molding material conduit first outlet to at least partially solidify; and

a second cooling coupler configured to couple the third molding material conduit with the first molding material tube

Coupled together via a second outlet, the second cooling coupler having cooling structure to remove heat therefrom to cause any material melt leaking between the second cooling coupler and the third molding material conduit and the first molding material conduit second outlet to at least partially solidify.

32. The multi-drop hot runner according to claim 31 wherein each of the first and second cooling couplers comprises a spigot connection.

33. The multi-drop hot runner of claim 31, further comprising a plurality of first molding material conduits.

34. The multi-drop hot runner of claim 31, wherein the first molding material conduit comprises a supply manifold, and the multi-drop hot runner further comprises a plurality of drop manifolds coupled to the supply manifold.

35. The multi-drop hot runner of claim 31, further comprising at least one intermediate manifold disposed between the supply manifold and at least one of the drop manifolds, and further comprising an intercooling coupler configured to couple the supply manifold and at least one of the drop manifolds together.

36. The multi-drop hot runner of claim 31, wherein the first cooling coupler is integrally formed with at least one of the second molding material conduit and the first molding material conduit first outlet.

37. A method of coupling together first and second molten material conduits, comprising the steps of:

placing an end of the first molten material conduit adjacent to an end of the second molten material conduit;

placing a coupler near the ends of the first and second molding material conduits;

securing the coupler near the ends of the first and second molten material conduits; and

cooling the coupler to cause molding material melt leaking between the coupler and the ends of the first and second conduits of molding material to at least partially solidify as molten material flows through the ends of the first and second conduits of molten material.

38. A method of sealing a connection between molten material mold conduits, comprising the steps of:

coupling ends of the molding material conduits together using a coupling structure; and

cooling the coupling structure with a coolant to cause any molding material leaking between the coupling structure and the end of the molding material conduit to at least partially solidify.