MELT DISPENSER FOR PLASTIC MOLDING
RELATED APPLICATIONS

This application claims priority from U.S. Provisional patent application 62/724,790, filed August 30, 2018, U.S. Provisional Patent Application 62/770,785, filed November 22, 2018, U.S.

Provisional patent application no 62/856,833, filed June 4, 2019, and U.S. Provisional patent application no. 62/866,059, filed June 25, 2019, the disclosures of which are incorporated herein by reference.

FIELD

This relates to production of plastic articles, and more particularly, to methods and apparatus for producing molten molding material.

BACKGROUND

Typical plastic molding machines, such as injection molding and blow molding machines, are large and heavy. Mold components are fixed to platens, which are operated by a fixed press, which may be mechanically or hydraulically actuated.

Typically, molding material is processed into a molding condition, namely, heated and melted, and delivered to a mold cavity from a supply subsystem. In the case of injection molding, such processing of molding material typically involves receiving solid pellets, and shearing those solid pellets by way of a screw or augur within a melt barrel. The screw and barrel may be collectively referred to an extruder. Extruders are typically large and heavy Facilities may at various times be required to produce molded articles formed of differing molding materials. Articles may be formed in different colours or having different material properties. For example, when changing to a new molding material, viable parts generally cannot be produced until the extruder and other system components are completely voided of the previous material. Such voiding typically requires extensive running of the system with the new material, which leads to waste.

SUMMARY

An example melt dispenser for plastic molding comprises: a barrel unit comprising: a barrel having an internal cavity for receiving molding material; and a feed screw rotatably received within the barrel for dispensing molten molding material through an outlet of the barrel; and a drive unit

comprising a drive for rotating the feed screw; a coupling mechanism selectively engageable to hold the barrel unit against the drive unit and to connect the screw to the drive; and an actuator operable to engage the coupling mechanism.

In some embodiments, the coupling mechanism comprises a spline coupled to the feed screw, wherein the spline is retractable to disengage from the feed screw.

In some embodiments, the spline is coupled to a drive shaft of the drive unit and to the feed screw and wherein the spline is retractable relative to the drive shaft and the feed screw.

In some embodiments, the feed screw is gravity-biased to fall out of contact with the drive unit upon retraction of the spline.

In some embodiments, the melt dispenser comprises an alignment device to position the barrel unit relative to the drive unit for engagement of the coupling mechanism.

In some embodiments, the alignment device comprises a leader pin.

In some embodiments, the leader pin of the alignment device of the barrel protrudes in a direction perpendicular to an longitudinal axis of the feed screw.

In some embodiments, the retaining mechanism comprises a clamp.

In some embodiments, the clamp releasably engages a stud projecting from the barrel unit.

In some embodiments, the barrel unit comprises a resin inlet port; and the drive unit comprises a resin feed port connected to the resin inlet port of the barrel unit to supply resin to the barrel unit.

In some embodiments, the barrel unit comprises a fluid intake port; and the drive unit comprises a fluid supply port in fluid communication with the barrel unit.

In some embodiments, the fluid intake port of the barrel is a water intake port.

In some embodiments, the barrel unit comprises a mating face which abuts the drive unit while the coupling mechanism is engaged, and the barrel unit further comprises a removal stud disposed opposite the mating face.

An example system comprises the melt dispenser and further comprises an automatic removal tool operable to engage the barrel unit for removal from the drive unit, and to install another barrel unit to the drive unit.

In some embodiments, the automatic removal tool comprises a rack with a plurality of nests, each for retaining a barrel unit.

An example melt dispenser for plastic molding, comprising: a barrel having an internal cavity for receiving molding material; a feed screw rotatably received within the barrel for dispensing molten molding material through an outlet of the barrel, the screw having a drive coupling connectable to a drive unit by operation of an actuator; and a retaining coupling for mating engagement by operation of an actuator with the drive unit to releasably retain the barrel against the drive unit.

In some embodiments, the drive coupling comprises a spline for connecting the feed screw to the drive unit.

In some embodiments, the spline is selectively connectable to the drive unit by extension and retraction of a spline coupling.

In some embodiments, the feed screw is gravity-biased to fall out of contact with the drive unit upon disengagement of the spline from the drive unit.

In some embodiments, the melt dispenser comprises an alignment device to position the barrel unit relative to the drive unit for engagement of the couplings.

In some embodiments, the alignment device comprises a leader pin.

In some embodiments, the leader pin of the alignment device of the barrel protrudes in a direction perpendicular to an longitudinal axis of the feed screw.

In some embodiments, the retaining coupling is operable to interlock with a clamp on the drive unit.

In some embodiments, the barrel unit comprises a resin inlet port for connection to a resin feed port to supply resin to the barrel unit.

In some embodiments, the barrel unit comprises a fluid intake port.

In some embodiments, the fluid intake port is a water intake port.

In some embodiments, the barrel unit comprises a mating face which abuts the drive unit while the coupling mechanism is engaged, and the barrel unit further comprises a removal stud disposed opposite the mating face.

An example system comprises the melt dispenser, and further comprises an automatic removal tool operable to engage the barrel unit for removal from the drive unit, and to install another barrel unit to the drive unit.

In some embodiments, the automatic removal tool comprises a rack with a plurality of nests, each for retaining a barrel unit.

An example set up method is for a plastic molding machine, comprising a first barrel unit for holding molding material and a drive unit for rotating a first screw within the barrel unit to dispense molten molding material. The method comprises: positioning the first barrel unit adjacent the drive unit; operating a drive mechanism actuator to rotationally couple the first screw to the drive unit.

In some embodiments, the operating a drive mechanism actuator comprises moving a spline into engagement with the first screw.

In some embodiments, the method comprises operating a retaining mechanism actuator to hold the first barrel unit against the drive unit.

In some embodiments, the operating a retaining mechanism actuator comprises engaging an interlocking device.

In some embodiments, the drive mechanism actuator causes movement along a first axis, and the retaining mechanism actuator causes movement along a second axis perpendicular to the first axis.

In some embodiments, the method comprises positioning the first barrel unit by engagement of an alignment device.

In some embodiments, the alignment device comprises a leader pin.

In some embodiments, the set up method comprises: operating the actuator to release a second barrel unit from the drive unit; and removing the second barrel unit from the drive unit.

In some embodiments, the set up method comprises automatically removing the second barrel unit from the drive unit using a removal tool, and automatically connecting the first barrel unit to the drive unit using the removal tool, after the automatically removing.

In some embodiments, automatically removing the second barrel unit comprises loading the second barrel unit on a rack of the removal tool.

In some embodiments, automatically connecting the first barrel unit comprises transferring the first barrel unit from the rack to the drive unit.

In some embodiments, the rack comprises respective nests for receiving each of the first and second drive units.

Embodiments may include the above-described features in any suitable combination.

Additional embodiments and features will be apparent to skilled persons in view of the disclosure herein.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings, which depict example embodiments:

FIG. 1 is a schematic diagram of a molding system;

FIG. 2 is a schematic diagram of a molding system with process cells defining multiple paths through the system;

FIG. 3 is an isometric view of a molding system;

FIG. 4A-4B are isometric views of a dispensing station of the system of FIG. 3;

FIGS. 4C-4E are isometric views of sub-assemblies of the dispensing station of FIG. 4A;

FIGS. 4F-4G are enlarged partial isometric views of a barrel unit;

FIG. 4F1 is a schematic view of a coupling for holding the barrel unit of FIGS. 4F-4G to a drive unit;

FIGS. 4I-4J are enlarged partial isometric views of the barrel unit of FIG. 4F with a drive unit;

FIG. 4K is a schematic diagram of a removal tool for removing a barrel unit from a drive unit;

FIGS. 4L-40 are enlarged partial cutaway views showing a process of coupling a barrel unit to a drive unit;

FIGS. 4P-4R are enlarged partial cutaway views showing a process of removing a barrel unit from a drive unit;

FIG. 4S is a schematic view of the removal tool of FIG. 4K installing a barrel unit to a drive unit;

FIG. 5 is a longitudinal cross-sectional diagram of the dispensing station of FIG. 4;

FIGS. 6A-6B are isometric and isometric cutaway views, respectively, of a vessel for transporting molding material;

FIGS. 7A-7B are isometric views of the material vessel of FIGS. 6A-6B and a carrier;

FIGS. 8A, 8B, 8C, and 8D are side and cross sectional views showing stages of a dispensing operation at the dispensing station of FIG. 4;

FIG. 9 is an exploded view of a gate assembly;

FIGS. 10A-10B are enlarged cross-sectional views showing operation of the gate assembly of FIG. 9;

FIG. 11 is an isometric view of a shaping station of the system of FIG. 3;

FIGS. 12A-12D are cross-sectional and isometric views of the shaping station of FIG. 11;

FIGS. 13A-13B are isometric and side views, respectively, of a linkage for a clamping assembly;

FIG. 13C is a diagram of forces on the linkage of FIGS. 13A-13B;

FIGS. 14A-14B are isometric and side views, respectively, of another linkage for a clamping assembly;

FIGS. 15A-15B are isometric and side views, respectively, of another linkage for a clamping assembly;

FIG. 16 is a side view of another linkage for a clamping assembly;

FIG. 17 is an isometric view of a core actuation assembly of the shaping station of FIG. 11 ;

FIGS. 18A-18B are isometric and cross-sectional views, respectively, of a core positioning actuator of the core actuation assembly of FIG. 17;

FIG. 19 is an isometric view of a loading actuator of the core actuation assembly of FIG. 17;

FIG. 20 is a partial cutaway view of the loading actuator of FIG. 19;

FIG. 21 A is a schematic view showing interlocking between the core positioning actuator of FIGS. 18A-18B and the loading actuator of FIG. 17;

FIG. 21B is a partial cross-sectional view of the core positioning actuator of FIGS. 18A-18B and the loading actuator of FIG. 17, showing interlocking;

FIG. 22 is an isometric view of a secondary mold opening actuator of the core actuation assembly of FIG. 17;

FIGS. 23A-23D are side, isometric, enlarged top and enlarged perspective views, respectively, of a shaper module of the shaping station of FIG. 11 ;

FIG. 24A-24B are front isometric and top elevation views of another shaping station;

FIG. 24C is a rear isometric view of the shaping station of FIG. 24A;

FIG. 24D is front isometric view of support structures of the shaping station of FIG. 24A;

FIGS. 24E-24F are isometric views of the support structures of FIG. 24D, cutaway at lines E-E and F-F in FIG. 24B;

FIG. 24G is an isometric view of the shaping station of FIG. 24A, cutaway to show internal components;

FIG. 24F1 is an enlarged partial cross-sectional of the shaping station of FIG. 24A;

FIGS. 24I-24J are isometric and cross-sectional views of the shaping station of FIG. 24A in a mold-open state;

FIGS. 24K-24L are isometric and cross-sectional views of the shaping station of FIG. 24A in a mold-open state, with the mold core in a molding position;

FIGS. 24M-24N are isometric and cross-sectional views of the shaping station of FIG. 24A in a mold-closed state;

FIGS. 240-24P are isometric and cross-sectional views of the shaping station of FIG. 24A in a mold-closed state, with a preload force applied to the mold core;

FIGS. 24Q-24R are isometric and cross-sectional views of the shaping station of FIG. 24A in a mold-open state;

FIGS. 24S-24T are isometric and cross-sectional views of the shaping station of FIG. 24A during mold removal;

FIG. 25A is a side perspective view of a one embodiment of part of a mold assembly;

FIG. 25B is a front elevation view of a portion of the part of the mold assembly of FIG. 25 A;

FIG. 25C are side perspective views of the embodiment of portions of the part of the mold assembly of FIG. 25A;

FIGS. 25D, E and F are similar side perspective views as FIG. 25C, of portions of the part of the mold assembly of FIG. 25A;

FIG. 25G is top perspective view of an embodiment of a mold cavity block;

FIG. 25F1 is a is top perspective view of an embodiment of a cavity plate that includes the mold cavity block of FIG. 25G;

FIG. 251 is top perspective view of an alternate embodiment of a mold cavity block;

FIG. 25J is top plan view of the mold cavity block of FIG. 251

FIG. 25K is another top perspective view of the mold cavity block of FIG. 251;

FIG. 26A and 26B are side perspective views of an alternate embodiment of portions of a mold assembly;

FIG. 26C is a top plan section view at part marked 26C in FIG. 26A;

FIG. 26D is a side perspective view of part of the embodiment of the portions of the mold assembly of FIGS. 26A and 26B;

FIG. 26E is a perspective view of a disconnected components of the part shown in FIG. 26D;

FIG. 26F is a perspective view of another disconnected components of the part shown in FIG. 26D;

FIG. 26G are rear elevation views of the disconnected component of the part shown in FIG. 26D;

FIG. 26F1 is top plan view of the mold cavity block used in the part of FIG. 26D;

FIG. 261 is a top perspective view of the mold cavity block of the part of FIG. 26D;

FIG. 26J is a top perspective view of an alternate mold cavity block that can be employed in the part of FIG. 26D;

FIG. 27A is a top perspective view of a base block;

FIG. 27B is a rear perspective view of the base block of FIG. 27A;

FIG. 28A is an assembly diagram for part of a mold assembly; and

FIG. 28B is a schematic view of a cooling fluid circuit.

FIG. 29 is a cross-sectional view of a mold of the shaping station of FIG. 11 and a vessel;

FIG. 30 is a sequence of overhead and isometric views showing sealing of a vessel;

FIG. 31 is an isometric view showing sealing of another vessel;

FIG. 32 is an isometric view of the actuator assembly of the shaping station of FIG. 11 ;

FIGS. 33A, 33B and 33C are isometric, cutaway and cross-sectional views, respectively, of a vessel and an actuation assembly at the shaping station of FIG. 11 ;

FIGS. 34A-34K are cross-sectional and partial cross-sectional views showing stages of a shaping operation at the shaping station of FIG. 11 ;

FIGS. 35A-35F are cutaway views of the vessel and actuation assembly of FIGS. 17A-17C, showing operations of the vessel and actuation assembly;

FIG. 36 is an exploded view of a gate assembly;

FIGS. 37A-37B are enlarged cross-sectional views showing operation of the gate assembly of FIG. 36;

FIG. 38 is an isometric view of a conditioning station and a shaping station of the system of FIG. 3.

FIG. 39 is a side cross-sectional view of the conditioning station of FIG. 38;

FIGS. 40A, 40B and 40C are side and cross-sectional views showing stages of a conditioning operation at the conditioning station of FIG. 38;

FIG. 41A is an isometric view of a shaping station;

FIG. 41B is a side view of a press of the shaping station of FIG. 41;

FIG. 42 is a side view of another shaping station;

FIG. 43 is a top view of the shaping station of FIG. 42;

FIG. 44 is an exploded view of a mold and services plates of the shaping station of FIG. 42;

FIG. 45 is an exploded view of the mold of FIG. 44;

FIG. 46 is a cross-sectional view of the mold of FIG. 44;

FIGS. 47A-47B are top and side schematic views of the shaping station of FIG. 42 during mold removal;

FIGS. 48A-48B are top and side schematic views of the shaping station of FIG. 42 during mold removal;

FIGS. 49A-49B are top and side schematic views of the shaping station of FIG. 42 during mold removal;

FIG. 50 is a schematic view showing mold components at a shaping station;

FIGS. 51 A, 51B, 51C and 51D are schematic views showing stages of a shaping operation with the mold components of FIG. 50;

FIG. 52 is a top plan view of the molding system of FIG. 3, showing a transport subsystem;

FIG. 53 is a plan view of an injection molding system in accordance with another embodiment;

FIG. 54 is a cross-sectional view along the lines I-I of FIG. 53;

FIG. 55A is a side view of a track section;

FIG. 55B is a cross-sectional view along the lines II-II of FIG. 55A;

FIG. 55C is a perspective fragmentary view of a portion of the track of the system of FIG. 55A;

FIG. 56 is a side view of a portion of the system of FIG. 53;

FIG. 57 is a perspective fragmentary view of another portion of the system of FIG. 53;

FIG. 58 is a perspective fragmentary view of a further portion of the system of FIG. 53;

FIG. 59 is a perspective fragmentary view of a yet a further portion of the system of FIG. 53;

FIG. 60 is a perspective detail view of a portion of FIG. 58;

FIG. 61 is a top view of a conditioner and shaper station and associated transfer system;

FIG. 62 is a side view of the stations and transfer system of FIG. 61

FIGS. 63A-63B are isometric and side views, respectively, of a carriage of the transfer system of FIG. 61;

FIG. 64 is a block diagram;

FIG. 65 is a perspective fragmentary view of a portion of a modified system;

FIG. 66 is a perspective detail view of a portion of FIG. 63.

FIG. 67 is a flow chart showing a method of transporting molding material; and

FIG. 68 is a flow chart showing a method of producing plastic molded products.

DETAILED DESCRIPTION

FIG. 1 schematically depicts an example plastic molding system 100 for producing plastic molded articles. As described in further detail below, plastic molding system 100 is capable of carrying out molding processes comprising dispensing, conditioning and shaping operations.

Plastic molding system 100 includes a plurality of process cells, each including one or more process stations at which an operation of a molding process can be performed. Specifically, the depicted embodiment comprises a dispensing cell 102, shaping cells 104, 106 and a conditioning cell 108. Other embodiments may include more or fewer cells and carry out molding processes with more or fewer process steps. Alternatively or additionally, plastic molding system 100 may include cells for other operations. For example, plastic molding system 100 may include cells for post-molding operations such as container filling, labelling or capping.

The process cells of plastic molding system 100 are connected by a transport subsystem 110.

Any of process cells 102, 104, 106, 108 may have more than one station of a given type. Transport subsystem 110 selectively connects stations of the process cells to one another. Transport subsystem 110 is configurable to define multiple possible process paths through process cells of molding system 100. For example, transport subsystem 110 may be capable of transporting an article from a given station in one process cell 102, 104, 106, 108, to a selected one of a plurality of possible stations in a another process cell 102, 104, 106, 108.

FIG. 2 schematically depicts an example embodiment with a dispensing cell 102 having 4 dispensing stations 102-1, 102-2, 102-3, 102-4; a shaping cell 104 having 8 shaping stations 104-1, 104-2, 104-3, 104-4, 104-5, 104-6, 104-7, 104-8; a shaping cell 106 having 2 shaping stations 106-1, 106-2; and a conditioning cell 108 having 2 conditioning stations 108-1, 108-2.

In the embodiment of FIG. 2, transport subsystem 110 is capable of connecting any of dispensing stations 102-1, 102-2, 102-3, 102-4 to any of shaping stations 104-1, 104-2,...104-8; and of connecting any of shaping stations 104-1, 104-2,... 104-8 to any of conditioning stations 108-1, 108-2; and of connecting any of conditioning stations 108-1, 108-2 to any of shaping stations 106-1, 106-2. Thus, numerous possible paths are defined through molding system 100. As depicted, there exist 128 unique combinations of one dispensing station 102, one shaping station 104, one conditioning station 108 and one shaping station 106 and each unique combination corresponds to a possible path. In some embodiments, one or more of the process cells may be omitted from some paths, such that additional

paths are possible. For example, conditioning at conditioning cell 108 or shaping at shaping cell 106 may not be required in all instances.

In other embodiments, more or fewer stations may be present in each process cell, and more or fewer paths through the molding system may be possible.

In some embodiments, process cells or stations of process cells may be physically separated from one another. Transport subsystem 110 may include apparatus for moving molding material through space between process cells or stations thereof. The apparatus may include one or both of vessels 124 (FIGS. 6A-6B) for holding molding material and carriers 125 (FIG. 7) for moving the vessels through space, e.g. along a guide or track, between the process cells or stations. In the embodiment described in detail herein, the vessel is selectively coupled to the carrier such that the vessel may be coupled and decoupled to the carrier at one or more process stations. In another embodiment, not shown, the vessel could otherwise be fixed to the carrier and the process stations configured to accommodate the vessel that remains connected with the carrier. In either case, the vessel may be thermally insulated from the carrier.

In the depicted embodiment, shaping cell 104 contains injection molding stations and shaping cell 106 contains blow molding stations. Conditioning cell 108 contains stations for thermally conditioning articles to prepare for blow molding. For example, injection molded articles formed at shaping cell 104 may cool after molding and be subsequently warmed to a temperature suitable for blow molding. Alternatively or additionally, stations of conditioning cell 108 may be configured to create a specific desired thermal profile in an article. For example, some shaping operations may call for an input article having a non-uniform temperature distribution. Stations of conditioning cell 108 may generate such temperature distribution by selectively heating specific regions, with or without a net transfer of heat into or out of the article. In some embodiments, articles may experience a net loss of heat in conditioning cell 108, despite warming of specific regions. Thus, stations of conditioning cell 108 may achieve thermal profiles not easily achieved by heat input at the dispensing cell 102.

As explained in further detail below, each station may have identical or unique characteristics. For example, the dispensing stations of dispensing cell 102 may each be configured to dispense the same or a different feedstock (e.g. a different material and/or colour). The shaping stations of shaping cells 104,

106 may be configured to mold articles having identical or different shapes, features or the like. The conditioning stations of conditioning cell 108 may each be configured to condition parts in common or to a different state. Accordingly, molding system 100 may be configured so that it is simultaneously capable of producing up to 128 identical or unique parts at any time. Alternatively or additionally, molding system 100 may be configured so that identical parts may be produced on multiple paths. For example, a single dispensing station can produce shots of feedstock to feed multiple stations of shaping cells 104, 106. In some embodiments, cells can be rapidly reconfigured. Accordingly, the number of system resources being used to produce parts of a given type may vary.

Each unique path through molding system 100 includes a unique combination of selected stations of dispensing cell 102, shaping cells 104, 106 and possibly other process cells such as, for example, the conditioning cell 108. Likewise, each unique combination of stations may produce finished articles with identical or unique characteristics. For example, different stations of dispensing cell 102 may produce articles having different colour material type or weight. Different stations of shaping cells 104, 106 may produce articles having different shapes. Different stations of conditioning cell 108 may produce articles having different shapes or other characteristics.

FIG. 3 is a perspective view of molding system 100. In the depicted embodiment, molding system 100 is for forming hollow plastic articles such as bottles or other containers. Molding system 100 has two shaping cells. Specifically, shaping cell 104 is an injection molding cell for molding a dose of feedstock material into a molded preform shape. Shaping cell 106 is a blow-molding cell (specifically, a stretch blow-molding cell) for transforming a preform of a particular shape into a finished hollow container of another, (e.g. a further-expanded) shape. Conditioning cell 108 prepare in-progress articles for operations performed at a shaping cell. Transport subsystem 110 links stations of the respective cells 102, 104, 106, 108. Links between cells are flexible. For example, in some embodiments, transport subsystem 110 links every station of each cell to every station of the neighboring cells. In other examples, some or all stations in a given cell are each linked to a plurality of stations in a neighboring cell. In some examples, some stations may be linked to stations of neighboring cells in a 1:1 manner. For instance, in the embodiment of FIG. 3, each station of dispensing cell 102 is linked to a plurality of stations of shaping cell 104, and each station of shaping cell 104 is linked to a plurality of stations of conditioning cell 108. However, each station of conditioning cell 108 is linked to one corresponding station of shaping cell 106.

Feedstock Dispensing

With primary reference to FIGS. 4A-4S, details of an example dispensing cell 102 will now be described.

Each station 102-1, 102-2, 102-3, 102-4 of dispensing cell 102 comprises one or more devices for melting a feedstock such as a plastic feedstock and for transferring the feedstock. In the depicted embodiment, the dispensing devices output molding material in doses of a specific size. However, in other embodiments, the dispensing devices may simply perform bulk transfer of molding material, without precise metering of dose size.

WHAT IS CLAIMED IS:

1. A melt dispenser for plastic molding comprising:

a barrel unit comprising:

a barrel having an internal cavity for receiving molding material; and

a feed screw rotatably received within said barrel for dispensing molten molding material through an outlet of said barrel; and

a drive unit comprising a drive for rotating said feed screw;

a coupling mechanism selectively engageable to hold said barrel unit against said drive unit and to connect said screw to said drive; and

an actuator operable to engage said coupling mechanism.

2. The melt dispenser of claim 1, wherein said coupling mechanism comprises a spline coupled to said feed screw, wherein said spline is retractable to disengage from said feed screw.

3. The melt dispenser of claim 2, wherein said spline is coupled to a drive shaft of said drive unit and to said feed screw and wherein said spline is retractable relative to said drive shaft and said feed screw.

4. The melt dispenser of claim 2 or claim 3, wherein said feed screw is gravity-biased to fall out of contact with said drive unit upon retraction of said spline.

5. The melt dispenser of any one of claims 1 to 4, comprising an alignment device to position said barrel unit relative to said drive unit for engagement of said coupling mechanism.

6. The melt dispenser of claim 5, wherein said alignment device comprises a leader pin.

7. The melt dispenser of claim 6, wherein said leader pin of said alignment device of said barrel protrudes in a direction perpendicular to an longitudinal axis of said feed screw.

8. The melt dispenser any one of claims 1 to 7, wherein said retaining mechanism comprises a clamp.

9. The melt dispenser of claim 8, wherein said clamp releasably engages a stud projecting from said barrel unit.

10. The melt dispenser of any one of claims 1 to 9, wherein,

said barrel unit comprises a resin inlet port; and

said drive unit comprises a resin feed port connected to said resin inlet port of said barrel unit to supply resin to said barrel unit.

11. The melt dispenser of any one of claims 1 to 10, wherein,

said barrel unit comprises a fluid intake port; and

said drive unit comprises a fluid supply port in fluid communication with said barrel unit.

12. The melt dispenser of claim 11 , wherein said fluid intake port of said barrel is a water intake port.

13. The melt dispenser of any one of claims 1 to 12, wherein said barrel unit comprises a mating face which abuts said drive unit while said coupling mechanism is engaged, and said barrel unit further comprises a removal stud disposed opposite said mating face.

14. A system comprising the melt dispenser of any one of claims 1 to 13, and further comprising an automatic removal tool operable to engage said barrel unit for removal from said drive unit, and to install another barrel unit to said drive unit.

15. The system of claim 14, wherein said automatic removal tool comprises a rack with a plurality of nests, each for retaining a barrel unit.

16. A melt dispenser for plastic molding, comprising:

a barrel having an internal cavity for receiving molding material;

a feed screw rotatably received within said barrel for dispensing molten molding material through an outlet of said barrel, said screw having a drive coupling connectable to a drive unit by operation of an actuator; and

a retaining coupling for mating engagement by operation of an actuator with the drive unit to releasably retain the barrel against the drive unit.

17. The melt dispenser of claim 16, wherein said drive coupling comprises a spline for connecting said feed screw to said drive unit.

18. The melt dispenser of claim 17, wherein said spline is selectively connectable to said drive unit by extension and retraction of a spline coupling.

19. The melt dispenser of claim 17 or claim 18, wherein said feed screw is gravity-biased to fall out of contact with said drive unit upon disengagement of said spline from said drive unit.

20. The melt dispenser of any one of claims 16 to 19, comprising an alignment device to position said barrel unit relative to said drive unit for engagement of said couplings.

21. The melt dispenser of claim 20, wherein said alignment device comprises a leader pin.

22. The melt dispenser of claim 21, wherein said leader pin of said alignment device of said barrel protrudes in a direction perpendicular to an longitudinal axis of said feed screw.

23. The melt dispenser any one of claims 16 to 22, wherein said retaining coupling is operable to interlock with a clamp on said drive unit.

24. The melt dispenser of any one of claims 16 to 23, wherein,

said barrel unit comprises a resin inlet port for connection to a resin feed port to supply resin to said barrel unit.

25. The melt dispenser of any one of claims 1 to 24, wherein,

said barrel unit comprises a fluid intake port.

26. The melt dispenser of claim 26, wherein said fluid intake port is a water intake port.

27. The melt dispenser of any one of claims 16 to 26 wherein said barrel unit comprises a mating face which abuts said drive unit while said coupling mechanism is engaged, and said barrel unit further comprises a removal stud disposed opposite said mating face.

28. A system comprising the melt dispenser of any one of claims 16 to 27, and further comprising an automatic removal tool operable to engage said barrel unit for removal from said drive unit, and to install another barrel unit to said drive unit.

29. The system of claim 28, wherein said automatic removal tool comprises a rack with a plurality of nests, each for retaining a barrel unit.

30. A set up method for a plastic molding machine, comprising a first barrel unit for holding

molding material and a drive unit for rotating a first screw within said barrel unit to dispense molten molding material, the method comprising:

positioning said first barrel unit adjacent said drive unit;

operating a drive mechanism actuator to rotationally couple said first screw to said drive unit.

31. The set up method of claim 30, wherein said operating a drive mechanism actuator comprises moving a spline into engagement with said first screw.

32. The set up method of claim 30 or claim 31, comprising operating a retaining mechanism

actuator to hold said first barrel unit against said drive unit.

33. The set up method of claim 32, wherein said operating a retaining mechanism actuator

comprises engaging an interlocking device.

34. The method of claim 32 or claim 33, wherein said drive mechanism actuator causes movement along a first axis, and said retaining mechanism actuator causes movement along a second axis perpendicular to said first axis.

35. The set up method of any one of claims 30 to 33, comprising positioning said first barrel unit by engagement of an alignment device.

36. The set up method of claim 34, wherein said alignment device comprises a leader pin.

37. The set up method of any one of claims 30 to 36, comprising:

operating said an actuator to release a second barrel unit from said drive unit; and

removing said second barrel unit from said drive unit.

38. The set up method of claim 37, comprising automatically removing said second barrel unit from said drive unit using a removal tool, and automatically connecting said first barrel unit to said drive unit using said removal tool, after said automatically removing.

39. The set up method of claim 38, wherein automatically removing said second barrel unit

comprises loading said second barrel unit on a rack of said removal tool.

40. The set up method of claim 39, wherein automatically connecting said first barrel unit

comprises transferring said first barrel unit from said rack to said drive unit.

41. The set up method of claim 40, wherein said rack comprises respective nests for receiving each of said first and second drive units.

Ill