HK1050871B - Filament cassette and loading system - Google Patents

Description

Silk thread box and loading system

Technical Field

The invention relates to a layered manufacturing technology of a three-dimensional structure on a substrate by spinning; and more particularly to manufacturing techniques for forming three-dimensional structures by spraying a curable, fluid, dynamic modeling material onto a corresponding substrate, wherein the modeling material is supplied in filament form.

Background

Three-dimensional models are widely used in art evaluation, mathematical CAD model validation, hard tool manufacturing, mutual interference and space allocation studies, and functional testing. The layered spin former on the substrate can form a three-dimensional structure by ejecting a curable modeling material through a spinneret in a predetermined pattern according to design data provided by a computer-aided design (CAD) system. A liquid or solid feedstock of modeling material is provided to the spinneret. One technique is to supply the modeling material in the form of a filament bundle, and deposit the modeling material in a solid state on the substrate by bringing the modeling material stock to a flowable temperature through a liquefier.

Examples of apparatus and methods for spinning a three-dimensional structure on a substrate are given in U.S. patent No. 4,749,347 to valvaara, U.S. patent nos. 5,121,329 and 5,340,433 to Crump, U.S. patent No. 5,503,785 to Crump et al, U.S. patent No. 5,900,207 to Danforth et al, U.S. patent No. 5,764,521 to Batchelder et al, U.S. patent No. 6,022,207 to Dahlin et al, U.S. patent No. 6,067,480 to Stuffle et al, and U.S. patent No. 6,085,957 to Batchelder et al; all of the above patents are assigned to Stratasys corporation, which is also the assignee of the present invention.

In a pattern building machine using filament feeding, the modeling material is fed in the form of flexible filaments wound on a supply spool disc, as described in U.S. Pat. No. 5,121,329. A curable material, which is suitably cured on the previous layer and can be supplied as a flexible filament, is used as the moulding material. A spinneret, including a liquefier and a feed nozzle, receives the supplied filaments, liquefies them in the liquefier to a liquid state, and forces the liquefied molding material through the nozzle onto a substrate contained within the build volume. The modeling material is laminated within the area defined by the CAD model. The ejected modeling material liquefies over the previously deposited material and solidifies to form a three-dimensional structure similar to a CAD model. In the case of a mold made of a molding material that is heat curable at a reduced temperature, the build volume is preferably a suitable chamber that is heated to a temperature above the curing temperature of the molding material as it is deposited and then gradually cooled to relieve the material stresses. As described in U.S. patent No. 5,866,058, this method allows the mold to be annealed during the build process, thereby relieving stress in the mold and producing little to no deformation.

In the layered deposition of curable material to build three-dimensional structures, a support layer or structure is built underneath the cavities or protruding overhanging portions of the structure to be built, which portions cannot be supported by the building material itself. For example, if an internal model of an underground cavern is being constructed and the prototype of the cavern is being constructed from the bottom up, then a stalactite-like support is required for temporary support until the uppermost "ceiling" is completed. The support structure may be constructed using the same deposition techniques and equipment as used for deposition modeling of the modeling material. The building equipment, under the control of appropriate software, can form additional geometries that can provide support for the cavities or protruding overhangs of the model to be formed. The support material may be sprayed, deposited through different nozzles in the pattern forming apparatus, or built up with the nozzle itself from which the pattern material is sprayed. The support material is selected so that it adheres well to the pattern forming material during the process of model construction and is readily removable from the constructed model after it has been formed. Various combinations of mold materials and their support materials are known, as described in U.S. Pat. No. 5,503,785.

The prior art Stratasys FDM three-dimensional model forming machine employs the filament supply apparatus disclosed in the above patent: the material supply process for supplying the molding material filament to the molding machine is accomplished by winding the filament of the molding material on a reel, which is mounted on a rotating shaft. The filaments are made of a thermoplastic or waxy material. The user manually feeds the raw material filaments: the filaments are drawn from a spool and the straightened filaments are passed through a conduit made of a less frictional material until the filaments are fed to a pair of motor driven feed rollers included in a spinneret. The feed rollers advance the filaments further into a liquefier included in the spinneret. Within the liquefier, the filaments are heated to a temperature at which they melt and can flow. As the feed rollers continuously push the feedstock filaments into the spinneret, the force of the advancing filaments causes the flowable modeling material to be ejected from the nozzle and deposited onto a substrate that is removably mounted to the workpiece table. The flow rate of the material ejected from the nozzle is a function of the feed rate of the filaments to the spinneret and the size of the nozzle opening. The controller controls the movement of the spinneret in a horizontal X-Y plane, controls the movement of the workpiece stage in a vertical Z direction, and controls the feed rate of the filaments to the spinneret by the feed rollers. By controlling these process parameters in concert, the modeling material can be "beaded" and layered at the areas specified by the CAD model at the desired flow rates. The ejected modeling material solidifies upon cooling, thereby forming a three-dimensional solid structure.

The filament used by the Stratasys FDM three-dimensional model forming machine is a moisture sensitive material such as ABS thermoplastic. In order for the machine to work properly and to build accurate and robust models, the modeling material must be in a dry environment. The filament reels used in the machine therefore need to be placed in a moist package together with the desiccant package during transport. The spools of filament need to be placed in the package before being loaded into the molding machine. While the spindle used for mounting the reel is located in a "dry box" -i.e. an area of the machine that is kept at a low humidity. The user needs to put a spool of filament with a desiccant pack into this "dry box" and then remove the desiccant. After manually feeding the filaments to the feed rollers, the user closes the door of the "drying box" and can then cause the machine to start the work of building the model. To remove the spool of filament from the machine, the user manually winds the filament back onto the spool. A description of the prior art method of loading reels into a "dry box" of a three-dimensional model forming machine is disclosed in us patent No. 6,022,207.

It is now common to manually feed filaments to a spinneret as a tedious task. In addition, in practice, users often forget to replace old desiccant with new one and leave the old desiccant in the "dry box," which will cause the humidity inside the "dry box" to exceed acceptable levels. Meanwhile, the door of the "dry box" may allow moist air to enter the sealed area during opening and closing. The reels with the incompletely consumed filaments are exposed to a humid environment when they are removed from the machine, which may also cause them to become infected. These problems with moisture can be wasteful when the user is formulating the type and color of molding material. Furthermore, the modeling materials that Stratasys FDM three-dimensional modeling machines are expected to employ are quite sensitive and fragile to moisture and can be contaminated in a matter of minutes. For some materials, the moisture level entering the oven during the time the door of the "oven" is opened to load or unload the filament spools is unacceptable, which reduces the amount of molding material available for use in such machines.

It is therefore desirable to provide an apparatus and method for feeding a three-dimensional modeling machine with wire that simplifies the loading and unloading operations and reduces the likelihood of moisture entering the machine. It is also desirable to facilitate the removal of unused strand from the machine, storage and later reuse.

Disclosure of Invention

The invention provides a filament cassette, comprising: a dry, air-tight chamber for receiving a rotatable spool around which said forming filament is wound that is flowable when heated; a sealed filament path from said chamber to the outlet; feeding means for feeding the filament from said spool through said passage; and means for preventing air from entering said chamber; wherein the filament magazine is used to provide formed filaments to a three-dimensional forming machine.

A method of using the above-described filament magazine of the present invention to provide formed filament material to a three-dimensional forming machine, the method comprising the steps of inserting the magazine into a fill bay of the forming machine; a strand of filament clamped in the filament channel of the filament cassette; and feeding the filament material out of the filament magazine outlet into the former tube.

A method of assembling the above-described filament cassette of the present invention, the method comprising the steps of: providing a filament magazine comprising a chamber, a filament path from the chamber to an outlet and means for feeding filament along the filament path; loading a rotatable spool wound with a forming wire into a chamber, wherein the forming wire is flowable when heated; drying the chamber and the wound strand; and sealing the box after loading the filament material to hermetically seal the chamber.

In a first embodiment, the feeding device includes a roller that receives a rotational force from an external driving wheel; in a second embodiment, the feeding means comprises a roller manually operated by the user. The filament cassette is air tight to protect moisture sensitive filament materials from environmental contamination.

The filament cassette receiver in the molder includes a tube and drive means. The conduit receives the filaments from the filament magazine outlet and directs them along a filament path to the forming machine. The drive means feeds the filament through the conduit in response to control signals from the controller. The filament cassette can be unloaded from the machine by controlling the drive, i.e. the filament is wound back into the filament cassette via the tube. In the preferred embodiment, the keying structure allows the pod to be loaded into and unloaded from the loading bay of the machine, allowing both the pod to be loaded and unloaded. One or more wire loading devices may be used in a single molder, each for receiving a wire magazine.

Drawings

FIG. 1 is a schematic perspective view of a filament material feeding apparatus for a prior art matrix spray-compression three-dimensional modeling machine.

Fig. 2 shows a first embodiment of a filament cassette being loaded into a first embodiment of a three-dimensional model forming machine.

Fig. 3 is an exploded view of the first embodiment of the filament cassette.

Fig. 4 is an exploded view of the bottom housing and spool of the filament cassette shown in fig. 3.

FIG. 5 is a partially exploded view of the filament magazine of FIG. 3 showing filament material in the filament path and the mounted circuit board.

Fig. 5A is a partial detail view showing another configuration of the circuit board mounted on the first embodiment of the cassette.

Fig. 6 is a perspective view of the first embodiment of the pod showing the bottom, sides and tail of the pod.

Fig. 7 is a front view of the first embodiment of the filament cassette.

Fig. 8 is a top plan view of a first embodiment of the pod receptacle of the present invention.

FIG. 9 is a front view of the first embodiment of the pod receptacle.

FIG. 10 is a perspective view of a portion of a detail showing the filament feeding structure of FIG. 8 as part of the pod receptacle.

Fig. 11A is a top plan view of a filament cassette loaded into the filament cassette receiver of fig. 8, showing the filament feeding device in a rest position.

FIG. 11B is a top plan view of a filament cassette loaded into the filament cassette receiver of FIG. 8, showing the filament feeding device in a driving position.

Fig. 12 is a detail perspective view of the filament feeding device of fig. 11B in cooperation with the first embodiment of the filament magazine.

FIG. 13 is a perspective view of a filament loading device of a second embodiment of a three-dimensional modeling machine.

Fig. 14 is a perspective view of a second embodiment of a filament cassette.

Fig. 15 is an exploded view of the second embodiment of the filament cassette (the guide module is not shown).

Fig. 16 is a perspective view of a cartridge of the second embodiment of the filament cassette.

Fig. 17 is a perspective view of the guide module of fig. 14 with the operating door open.

Fig. 18 is an exploded view of the pod receiver of fig. 13.

FIG. 19 is a cross-sectional view of the filament loading device of FIG. 13 taken along line 19-19.

Detailed Description

As shown in fig. 1, in a spinning type three-dimensional model forming machine, a filament raw material is generally supplied to a spinneret 20 by a filament feeder 10. Spool 12 is secured to a spindle 16 on which filament 14 is wound. The filaments 14 are made of a modeling material that is required to build a three-dimensional model (or build a support structure for a three-dimensional model). The filaments are small in diameter, typically around 0.070 inches.

The filaments 14 are fed through a conduit 18, the conduit 18 being made of a material having a low coefficient of friction and preferably provided with Teflon^tmAnd the like. The conduit 18 directs the filaments 14 to a spinneret 20. A pair of feed rollers 22 secured to the spinneret 20 receive the supplied filaments 14 and deliver them to a liquefier 26 carried by the spinneret 20. As shown, the outer edge of the feed roller 22 is wrapped with a rubber material so that the filaments 14 can be gripped therebetween. As can be seen from the figures, it is,of the two feed rollers 22, one is a drive wheel, driven by a motor 24 under the control of a controller 25; the other is an idler pulley. Liquefier 26 is heated to liquefy filament 14. The liquefier 26 terminates in a nozzle 28 having an orifice 30 for pressurizing the liquefied modeling material. Feed roller 22 causes filament 14 to enter liquefier 26 and subjects liquefier 26 to a "pumping" action, which may itself act as a piston, thereby establishing a liquefier pump. This pumping pressure causes the liquefied modeling material to exit orifice 30 at a volumetric flow rate. The volumetric flow rate is a function of the size of the orifice 30 and the rotational speed of the feed roller 22. By controlling the motor 24, the feed rate of the filaments 14 and thus the injection rate of the liquefied molding material can be effectively controlled.

The spinneret 20 may be driven in the X-Y horizontal plane by an X-Y conveyor 34, the conveyor 34 receiving drive signals from the controller 25 in accordance with design data for the CAD model. As the spinneret 20 moves in the X-Y plane, the liquefied modeling material is controllably layered by the spinneret 30 onto a planar substrate 32 (only partially shown in fig. 1). After each layer is fired, the substrate 32 is reduced by a predetermined dimension along the Z-axis by a Z-axis conveyor 36, which is also driven by the controller 25. The spun material may be melted and solidified to form a three-dimensional structure similar to a CAD model. The support material may also be sprayed in a similar manner in conjunction with the spray-pressing process of the molding material to build up a support layer or support structure for the three-dimensional structure.

Those skilled in the art will appreciate that a variety of different molding machines and molding processes are possible. For example, relative motion in any three-axis space between the spinneret 20 and the substrate 32 can be used to construct a three-dimensional structure. The feed rollers and motors may also take a variety of forms. Various roller configurations are described, for example, in U.S. patent No. 5,121,329, which discloses that both rollers may be driven (e.g., coupled to each other by a timing belt), additional rollers may be added, or that the rollers may be spring biased without a rubber coating to ensure contact friction with the filament, etc. Any type of motor that can drive the feed rollers at a controlled rate, such as a servo motor or stepper motor, may be used. Likewise, various different spinneret configurations may be employed to receive and spray-press different types and colors of filament material from the various feed devices. For example, the spinneret may be provided with two sets of feed rollers, each set of rollers being driven by its motor for feeding two different filament materials from two reels, as disclosed in U.S. Pat. Nos. 5,121,329, 5,503,785 and 6,004,124.

Example 1

In the present invention, a spool wound with a coil of filament is placed in a filament magazine. Fig. 2 illustrates one embodiment of a mold forming machine 40 having two vertically arranged charging bays 42 for receiving a first embodiment 44 of filament cassettes. As shown, one filament cassette 44 has been loaded into the lower magazine and a second filament cassette 44 is being loaded into the upper magazine 42. Each box contains a spool of filament material. Preferably, one filament magazine 44 supplies filaments of the pattern forming material, while the other filament magazine 44 supplies filaments of the support material. The molder 40 has two liquefiers 26, shown in fig. 1, each for receiving filament from one filament magazine.

As will be described in greater detail below, each magazine 42 includes a filament magazine receiver 46 that cooperates with the filament magazine 44 and supplies the filaments 14 from the filament magazine 44 to the conduit 18 of the filament feeder 10. The user may load the filament cassette 44 into the mold forming machine 40 by: the pod 44 is advanced into the engagement position within the magazine 42 by holding the pod in an upright position and aligning the lead-in end 48 of the pod 44 with one of the magazine 42. In this way, the pod 44 may be well fitted to the magazine 46.

Fig. 3-7 illustrate the detailed construction of the filament cassette 44. As shown in fig. 3-4, the filament cassette 44 includes an upper shell 50, a lower shell 52, and a spool 54 around which the filament 14 is wound. The upper and lower shells 50, 52 are held together with the spool 54 sandwiched therebetween by a set of four bolts 55 (not shown). The lower shell 52 has a boss 56 and the upper shell 50 has a boss 58. Annular grooves 59 in the upper and lower shells 50 and 52 surround the bosses 56 and 58. The upper and lower shells 50, 52 each have seven compartments 60 distributed around the periphery of the recess 59. The bushings 56 and 58 together form a shaft about which the spool 54 can rotate within a chamber defined by an annular recess 59. A desiccant packet 62 is placed within the compartment 60 to maintain the chamber of the pod 44 in a dry state. A narrow groove 64 in the lower shell 52 forms a closed loop around the annular recess 59 and the compartment 60. A seal 68 is placed in the groove 64. A flange 66 on the upper shell 50 may interfit with the channel 64. The gasket 68 prevents air from entering the spool 54 of the cartridge 44 when the upper and lower shells 50, 52 are snapped together.

As best seen in FIG. 5, the upper and lower shells 50, 53 each have a narrow groove 70 leading from the annular recess 59 to the lead-in end 48 of the filament cassette 44. The grooves 70 define the passage of the filaments before they reach the orifices 72 of the filament magazine 44. As shown in fig. 5, the roller 76 is disposed opposite the roller 78 along the groove 70 of the lower case 52. As shown, roller 76 rotates about a suspension shaft 80, while roller 78 rotates about a fixed shaft 82. The levitation axis 80 is located in a cylindrical space 81 between the upper and lower shells 50 and 52 in a direction perpendicular to the filament path. The fixed shaft 82 is located in a cylindrical space 83 between the upper and lower cases 50 and 52. The force on roller 76 draws it toward roller 78 so that it can grasp filament 14 in the channel. Alternatively, both rollers may have a fixed axis, but are disposed close enough to grasp the filament in the channel. The rollers may have an elastoplastic surface to assist in gripping the filaments 14.

The groove 70 in the lower shell 52 forms a filament path across the groove 64 between the annular groove 59 and the roller pairs 76 and 78. A retainer 84 integrated with the gasket 68 is also disposed at this portion. The retainer 84 has a central bore 85 with a diameter approximately equal to the diameter of the filament.

The upper shell 50 and the lower shell 52 each have another groove 86 that is parallel to the groove 70. The upper and lower grooves 86 define a recording pin receiving space 88 that begins at the lead-in end 48 of the filament cassette 44 and ends before the seal 68. The cavity 88 has an enlarged entrance and an elongated neck. The entrance to the cavity 88 is shown in figure 7. The upper and lower shells 50, 52 each have a recess 89 to the right of the groove 86, which together define a cavity at the lead-in end 48 of the cartridge 44. On the lower case 52, a circuit board is mounted in the recess 89.

In the embodiment shown in fig. 5, a circuit board 92 with an EEPROM96 chip on its upper surface is mounted horizontally on the base of the socket 89 by two screws 94. The circuit board 92 has a projecting conductive strip passing through the recess 89 and thus can be interconnected with a card connector. In another embodiment shown in fig. 5A, a circuit board 102 is mounted longitudinally in pocket 89 by bolts 104. An EEPROM96 chip is mounted on the inside (not shown) of circuit board 102, with a pair of electrical contacts 106 on the outside.

EEPROM96 may function as an electronic identifier for the pod 44. Information from EEPROM96 identifies filament magazine 44 and filament 14, such as the type of material comprising the filament. In addition, EEPROM96 can also hold a linear supply of filament in filament magazine 44. When the filament cassette 44 is loaded into the mold machine 40, the EEPROM96 is electrically connected to the controller 25 as described below. As the filaments 14 are continuously fed from the filament magazine 44 to the forming machine 40, the controller 25 continuously modifies the linear metering of the filaments 14 remaining in the filament magazine 44. This allows the controller 25 to prevent the forming machine 40 from continuing to operate when there is no more wire. The EEPROM may be any form of readable and writable data storage device. In U.S. patent No. 5,939,008, a case where such a data storage device is used as a filament marker is described.

The assembly process of the filament magazine 44 is to mount the spool 54 with the filament 14 wound thereon on the boss 56 of the lower shell 52. The lower shell 52 is prepared by pressing the seal 68 into the groove 64 so that the retainer central aperture 85 is aligned with the groove 70. The circuit board 92 or 102 is fixed to the lower case 52. The fixed shaft 82 with the roller 78 is placed in the cylindrical space 82 of the lower case 52, and the floating shaft 80 with the roller 76 is placed in the elongated space 81 of the lower case 52. A bundle of filaments 14 drawn from the spool 54 passes through the central aperture 84 of the retainer and is then placed in the groove 70 of the lower shell 52 between the rollers 76 and 78. A desiccant packet is placed within each compartment 60. Once these fittings and items are in place in the lower shell 52, the upper and lower shells may be snapped together by four bolts 55 (or other suitable attachment and securing means). The bolts 55 are placed into the four bolt holes 108 of the lower case 52 and pass through the four bolt holes 109 of the upper case 50. The filament cassette 44 is now ready for loading into the molding machine 40.

After the filament cassette 44 is assembled, it may be placed in a vacuum-tight moisture-proof package for shipment or later use. Vacuum sealing is more desirable when filaments 14 are made of moisture sensitive materials. In addition, for moisture sensitive materials, the chamber containing the wound filaments in the filament magazine 44 should be dried prior to sealing. The filament cassette 44 is stored in a sealed package until the user is ready to load it into the molding machine 40.

When the filament 14 stored in the filament magazine 44 is used up or becomes unusable, the upper shell 50 may be separated from the lower shell 52, and the filament 14 wound on the spool 54 may then be replaced, refilling the filament magazine 44 and making it reusable. The EEPROM96 on circuit board 92 or 102 can be reset or a new EEPROM96 can be provided by replacing the circuit board.

Fig. 6 shows the right side, tail and bottom of the pod 44. As shown, the roller 76 extends through an opening 111 on the right side of the pod 44 to receive an externally applied rotational force. As will be described in greater detail below, roller 76 is preferably driven by a drive wheel 156 on the filament magazine receiver 46 to pull the filaments 14 through orifices 72.

The pod receiver 46 may cooperate with the pod 44 as shown in fig. 8-12. The pod receptacles 46 are mounted to the floor 110 of each of the pods 42. The bottom surface 110 of the capsule is preferably made of a flat sheet metal material. The pod receiver 46 includes a catch arrangement 112, reciprocating means 114 and drive means 116. The catch arrangement 112 is secured to the bottom surface 110 by a bracket 116. Latching mechanism 112 includes a solenoid 118, a lever 120 and a latch 122. Rod 120 is connected at one end to solenoid 118 and at the other end is integral with catch 122. Rod 120 extends downwardly from solenoid 118 through an opening in bottom surface 110 to a position generally parallel to bottom surface 110 and below bottom surface 110, and then tilts upwardly so that it can act as a fulcrum, allowing the position of catch 122 to alternate between above and below bottom surface 110. The catch 122 can move up and down through an opening 124 in the bottom surface 110.

Solenoid 118, under the control of controller 25, causes alternate upward and downward movement of rod 120, which causes alternate latching and unlatching of catch 122. When solenoid 118 is energized, the keyed end of rod 120 moves upward, placing latch 122 in the latched state. When the solenoid is no longer energized, the catch end of rod 120 moves downward, leaving the catch in an open state.

The shuttle 114 is secured to the base 110 by a bracket 126. The reciprocator 114 includes a piston 128, spring 130, guide 132 and frame 133. The piston 128 is parallel to and above the bottom surface 110. The piston 128 passes through an opening in the bracket 126 and is movable back and forth within the loading bay 42 as dictated by the guide rails 130. The front end of the piston 128 is connected to a frame 133, said frame 133 extending substantially perpendicular to the piston. The frame 133 is movable in a forward and backward direction together with the piston 128. A spring 130 is wound around the piston 128 and has a rear end connected to the front end of the bracket 126. The horizontal force on the frame 133 will cause the spring 130 to be compressed. When the force is removed, the spring 130 is released from compression, thereby moving the frame 133 and piston 128 forward. A pair of bearings 134 mounted on the bottom surface 110 are located below the frame 133. The bearing 134 may provide a low friction facing that provides support to the frame 133 in a plane parallel to the bottom surface 110 while facilitating fore and aft sliding of the frame 133.

An electrical connector 136, a positioning pin 138 and a pipe 140 are mounted on the frame 133. The electrical connector 136 has a front face configured to mate with the circuit board structure of the magazine 44 and a rear face configured to electrically connect to the controller 25. As shown, the electrical connector 136 has two resilient contacts 142 that mate with the electrical connection structure of the circuit board 102 of the magazine 44 (alternatively, the electrical connector 136 is a card-style connector, the contacts of which are connectable to the conductive contacts of the circuit board 92). The alignment pins 138 are mounted on the frame 133 on the right side of the electrical connector 136. A dowel pin 138 extends forwardly in the fill chamber and has a diameter approximately equal to the neck diameter of cavity 88 in cartridge 44. The conduit 140 is located to the right of the locating pin 138. The inlet 144 of the duct 140 faces the front of the cabin 42 and the outlet 146 thereof faces the rear of the cabin 42. The inlet 144 of the conduit 140 is aligned with the outlet 72 of the filament magazine 44 to receive the filaments 14 ejected from the outlet 72. Alternatively, the conduit 140 is sealed to the outlet 72 and the conduit 18. Filaments 14 entering conduit inlet 144 will enter conduit 18 through conduit outlet 146 and be eventually sent to liquefier 26.

The drive unit 116 is mounted to the floor 110 of the capsule by a bracket 148. The drive device 116 includes a solenoid 150, a motor 152, a gear set 154, a drive wheel 156 that rotates about a rotational axis, and a bearing block 160. Fig. 10-12 illustrate the structure of the drive device 116 in detail. The solenoid 150 has an actuator 162 mounted on the carriage 148 and thus reciprocally movable back and forth within the loading chamber 42. Energization of solenoid 150 is controlled by controller 25. When the solenoid is energized, the actuator 162 moves forward in the loading bay 42; when the power to the solenoid 150 is terminated, the actuator 162 moves toward the rear of the loading bay 42. A bearing block 160 carrying a motor 152, gear set 154 and drive wheel 156 is pivotally mounted on the bottom surface 110 in alignment, forward of an actuator 162. When the solenoid 150 is energized, the actuator 162 may rotate the bearing housing 116 clockwise. When the actuator 162 does not exert a force on the bearing seat 116, the bearing seat 116 is in an upward idle state. When the actuator 162 rotates the bearing block 116 counterclockwise, the drive wheel 156 is placed in the drive position; in this drive position, when a pod 44 is loaded into the loading bay 42, the drive wheel 156 will press against the floating axle roller 76.

The motor 52 drives a shaft 158 for rotation through a gear set 154 in response to control signals from the controller 25, as shown in FIG. 10. Rotation of the shaft 158 will cause rotation of the drive wheel 156. In its drive position, drive wheel 156 will cause rotation of pod roller 76. Release of the actuator 162 from the bearing housing 160 will rotate the bearing housing 160 back to its rest position. In another embodiment, where the pod roller has a fixed axle, the solenoid 150 may be disabled and the drive wheel 156 may be held in a drive position such that the drive wheel 156 acts on the pod roller with a constant pressure.

As described above, the user loads the magazine 44 into the molding machine 40 by pushing the magazine 44 into a loading bay 42 until a hard stop is encountered. Hard braking is provided by the pressure of the stop 164 and spring 1130 mounted on the bottom surface 110 of the capsule (as shown in figure 8). When the user removes the pod 44, the stop 164 moves back until the catch 122 catches on a flange 180 (shown in fig. 5) on the bottom surface of the pod 44. Prior to loading the pod 44, the catch 122 is placed facing up; the latch may be caused to lock the fuse box 44 when the controller 25 commands the solenoid 118. Catch 122 remains in its upward position until the user desires to remove filament cassette 44, at which point controller 25 de-energizes the solenoid, thereby moving catch 122 downward.

When the pod 44 is pushed into the loading bay 42, the locating pins 138 slide into the cavity 88 of the pod 44. The alignment pins 138 function to align the filament cassette 44 with the cassette receiver 46, and in particular, to offset torque that may be applied to the filament cassette 44 due to the connection of the drive system 116. With the cassette 44 aligned with the cassette receiver 46, the elastomeric joint 142 can mate well with the electrical connector 106 of the circuit board 102 to establish an electrical connection between the cassette 44 and the controller 25. When controller 25 senses the presence of EEPROM96, it can determine that cassette 44 is loaded. The controller 25 reads the metering data stored in the EEPROM 96. If the read metering data indicates that the amount of filament held in the filament cassette 44 is below a set "empty cassette" threshold, the user will be alerted to load a new filament cassette 44.

When the controller 25 senses that a cassette has been loaded, it may cause the solenoid 150 of the drive device 116 to enter an energized state. As described above, energization of the solenoid 150 causes rotation of the bearing block 160, thereby moving the drive wheel 156 to the drive position compressing the roller 76 of the filament cassette 44. The force of drive wheel 156 against roller 76 pushes roller 76 toward roller 78, thereby pinching filament 14 in the filament path. When the drive wheel 156 is driven by the motor 152 to rotate counterclockwise, the roller 76 is driven to rotate clockwise, thereby feeding the filament 14 into the conduit 140 and then into the conduit 8.

The filament magazine receiver 46 continues to advance the filament until it reaches the feed roller 22. The controller 25 may sense the presence of the filament 14 at the feed roller 22. The motor 24 is preferably a dc servo motor and the sensing is accomplished by monitoring the current load on the motor 24. To monitor the current load, the controller 25 places the motor 24 in an auto-loading start state. As the filament appears between the rollers 22, the current load will increase. When the controller 25 senses an increase in motor current load, the controller 25 commands the motor 24 and the pod receiver 46 to stop operating. In addition, when the controller 25 de-energizes the solenoid 150 to remove the force from the drive wheel 156 against the roller 76, the frictional force of the roller against the filament in the mold is lost.

Alternatively, as described above, the drive device 116 may be designed to maintain the drive wheel 156 in a fixed position so that a constant force is generated. In this configuration, it is possible to default to roller set 22 and feed filament 14 to liquefier 26 via the roller set of filament magazines 44. In this way, drive wheel 156 may be driven at a controlled rate to control the feed rate of filament 14 into the liquefier.

To unload the strand, the controller 25 causes the motor 24 to retract for a period of time during which the strand 14 may be pulled out of the liquefier 26 and feed roller 22. The controller 25 then disengages the pod 44 from the pod receptacle 46 and the user may remove the pod 44 from the loading bay 42. To eject the wire magazine from the machine, the user advances the wire magazine to the hard detent position to release the catch 122. Thereafter, the spring 130 pushes the reciprocating mechanism 114 forward, so that the filament cassette can be ejected.

The top and trailing edges of the filament magazine 44 each have a window through which a user can view the presence of filament in the magazine when loading and unloading the magazine 44. If there is still usable filament in the pod when the pod 44 is removed from the loading bay, the pod may be stored for later use. If the amount of filament material in the filament magazine is not sufficient for reuse, the filament magazine 44 may be refilled for later reuse

Example 2

Fig. 13 illustrates a filament loading device 178 mounted in a second embodiment of a molder 180 that can build molds from a supply of filament from a second embodiment of a filament cassette 184. The filament loading device 178 and filament magazine 184 are particularly well suited for use in molding with moisture sensitive materials. The filament loading device 178 includes four loading bays 182, four filament cassettes 184 (each containing a spool 186 around which a filament 188 is wound), four filament cassette receptacles 190, two communicating modules 192, and a drying system. The four loading bays 182 are arranged side by side in horizontal alignment in the front of the molder 180. Each pod 182 is adapted to receive a pod 184 having a pod receptacle 190 mounted on a top surface thereof for engaging a pod. The communication modules 192 are mounted to the frame 195 of the strand loading device 178 and each of them is connected to a pair of strand magazine receptacles 190.

The user may load the filament cassette 184 into the mold forming machine 180 by the following procedure: the pod 184 is held in an upright position by hand and pushed into a loading bay 182, and the catch 196 on the pod receiver 190 is grasped and the catch 196 is pushed forward to lower the pod receiver 190 to its lower position. In its lower position, the pod receptacle 190 may mate with the pod 184 and lock the pod 184 in its respective proper position. The filament is manually fed from each filament magazine 184 to its respective magazine receptacle 190 (described in detail below). The filament cassette receiver 190, under the control of the controller 25, can automatically feed filament forming material through the conduit 202 and the communication module 192 to the spinneret 20.

Each communication module 192 has two inlets 198, one air inlet 199 and one outlet 200. The input ports 198 are connected to corresponding magazine receptacles by conduits 202 to provide a passage for the filament from the receptacle 190 to the communication module 192. The output port 200 of each communication module 192 is connected to a length of conduit 204. Conduit 204 provides a passage for the filament from each communication module 192 to liquefier 26 (shown in FIG. 1). As filaments 188 of moisture sensitive material are fed from filament magazine 184 to liquefier 26, a drying system including a compressor 206, filter 208, and renewable desiccant 210 may be used to maintain a dry environment for the filament path, as will be described in further detail below.

At a given time, only one bundle of filaments is fed to the connectivity module 192 and each pair of feed rollers. Other filaments remain in the respective filament magazine receptacles 190. The filament magazine 184 that supplies filaments to the connectivity module 192 is referred to as the primary filament magazine; the filament magazine 184, which provides filaments that remain in the filament magazine receptacle 190, is referred to as an auxiliary filament magazine. Without user intervention, the molder 180 may perform a transition between the primary and secondary filament magazines, i.e., withdrawing the filaments from the primary filament magazine 184 to their respective receptacles, while feeding the filaments from the secondary magazine 184 to the feed roller 22 through the communication module 192. Thus, the original auxiliary filament cassette now becomes the main filament cassette. In a typical application, it is preferred that one communication module 192 receive the filaments of modeling material and another communication module 192 receive the filaments of support material. Thus, the molding machine 180 can automatically turn to the auxiliary feeding state when the filament box of the main feeding supplies the filament material completely, without wasting the process time of the mold molding. In this way, the molder 180 may run continuously and the user may evacuate the spent pod of replacement filament material. Alternatively, in the case where the main and auxiliary filament magazines 188 are separately loaded with different types of filaments, the magazine may be switched before the material is exhausted, so that the model may be constructed with different materials and colors.

Fig. 14-17 illustrate the construction of the pod 184 in detail. As shown, the filament magazine 184 includes a drum 212, guide module 214, and spool 186 for winding the filament coil 188. The cylinder 212 is formed by a barrel 216 upon which is pressed a flange 218. The interior of the cylinder 212 defines a chamber that houses the spool 186. Spool 186 is rotatable about hub 220 of base 216 and hub 221 of flange 218. Alternatively, a spring plate 222 may be added to the inside of the flange 218. Spring plate 222 has curved, needle-like barbs that allow spool 186 to only rotate in one direction to draw filament from magazine 184. The guide module 214 is mounted to the outlet 224 of the barrel 216 and provides an outlet path for the filament 188. The guide module 214 is secured to the cylindrical barrel 216 by six bolts (not shown) passing through corresponding bolt holes 232 (see fig. 15) in the barrel 216.

To accommodate filaments 188 of moisture sensitive material, the filament cassette 184 is made air tight. The cylinder 212 and the guide module 214 may be made of materials selected to prevent water vapor penetration, such as sheet steel and polypropylene, respectively. A moisture barrier 223 is sealed between flange 218 and barrel 216. Moisture within the cylinder chamber 212 is allowed to escape through an opening 226 in the cylinder 216, the opening 226 being sealed by a plunger 228. A length of moisture barrier 230 is preferably applied over the plunger 228 to further enhance the seal against the opening 226.

As shown in fig. 19, the filament 188 within the cylinder 212 is fed through the outlet 224 into the filament channel 236 of the guide module 214. The filament channel 236 extends from the guide module 214 to an outlet 238. Adjacent to the filament channel 236, the guide module 214 has a chamber 238 in which a ratchet 240 is mounted on a raised structure 242. The mounting structure of the raised structure 242 allows the ratchet 240 to press the filaments in the channel 236 against the channel wall 246. The user manually rotates the ratchet 240 in a clockwise direction to draw the filament out of the exit orifice 238 and feed it along the filament path 236. To prevent counter-clockwise rotation of the ratchet 240 (which would urge the filament toward the barrel 212 where it can only be operated by opening the barrel), an anti-backup plate 244 is preferably mounted in the chamber 238 in juxtaposition to the ratchet 240. One skilled in the art will appreciate that other devices may be used to feed the filament in place of the ratchet wheel 240. For example, a raised former may be formed on the cylindrical wall 246, and a user may manually advance a filament that rides on the former. Alternatively, an idler wheel may be used in place of the raised profile or in combination with the ratchet 240.

For filaments 188 of moisture sensitive material, air should be prevented from entering the filament channel 236. The guide module 214 has a removable plunger cap 248 that seals the outlet 238 and a chamber door 250 that closes the chamber 238. The plunger cap 248 is tightly pressed against a pair of recesses 254 of the guide module 214 such that the compressible seal 252 under the plunger cap 248 covers the outlet 238. The user may remove the plunger cap 248 while inserting the cartridge 184 into the machine 180. The guide module preferably has a second pair of recesses 256 where the plunger cap 248 may be placed when it is removed from the first pair of recesses. The chamber door 250 is pivotable about a hinge 260 with a compressible seal 258 on its inner surface. With the chamber door 250 open, the user can operate the roller 240 to feed the filament into the machine 180; in other cases, the chamber door should be closed. Another compressive seal 234 is located between the guide module 214 and the barrel 216 to provide further sealing of the cartridge 184.

EEPROM96 (described above in example 1) may be configured in the steering module 214. The circuit board 102 with the EEPROM96 is mounted on the recess 262 of the guide module 214 with a pair of electrical contacts facing outward and the EEPROM96 facing inward. The circuit board 102 is secured to the guide module 214 by three bolts 266. For ease of use, the guide module 214 preferably functions as a handle for the pod 184. In the illustrated embodiment, the guide module 214 includes a pair of handles 264 (shown in FIG. 14) on opposite sides thereof.

The assembly process of the cartridge 184 is as follows: the spool 186 of filament 188 is placed on the hub 220 of the barrel 216 and the filament is then fed into the guide module 214. The filament is placed in the filament channel 236 in contact with the roller 240. The desiccant packet 62 (as described in example 1) is placed in the compartment defined by the spokes 225 of the spool 186. The flange 218 is then pressed onto the barrel 216 and the sealing band 223 is sealed. Thus, the assembly work before use is completed. After the filaments in the filament magazine 184 are used up or become unusable, the filament magazine 184 can be refilled and made reusable by the following procedure: the flange 218 on the barrel 212 is removed and the filament 188 on the spool 186 is replaced. When the cassette 184 is refilled, the circuit board 102 is reset to carry the EEPROM96, or replaced with a new EEPROM96 by replacing the circuit board.

For moisture sensitive materials, the filament cassette 184 containing the filaments wound on the spool should be dried so that the moisture level does not damage the mold formation. For most high temperature thermoplastics, for example, polycarbonate/ABS blends and Ultem^tmFor materials, acceptable moisture levels were less than 700ppm (as measured by the Karl Fischer method). The drying of the filament material may be carried out by a variety of methods.

The material may be dried by placing the filament magazine 184 containing the wound filaments in a vacuum drying oven. The wire box 184 is placed in the dry box prior to mounting the circuit board 102 and plugging the aperture 226. The temperature of the drying oven is adjusted to a temperature suitable for the particular molding material. For high temperature thermoplastics, the drying temperature is typically 175-220 degrees Fahrenheit. The drying cabinet is provided with a vacuum pump for maintaining a dry environment in the cabinet. The opening 226 in the barrel 212 facilitates placing the chamber of the barrel 212 into the environment of the drying oven, thereby allowing the material to be dried. When the humidity reaches the level allowed by the molding material, the opening 226 is completely closed, and the filament cassette 184 is taken out of the drying box. For high temperature thermoplastics, drying times of 4 to 8 hours are contemplated to achieve a moisture level of 300 ppm. The circuit board 102 is then mounted. The assembled filament cassette 184 is vacuum packed in a moisture-proof packaging bag until it is loaded into the mold forming machine.

Or the desiccant packet 62 may be used to dry the molding material in the cavity of the drum 212 without a drying oven. It has been demonstrated that placing a combination of Tri-Sorb molecular sieve and calcium oxide desiccant in the pod 184 and enclosing the pod in a moisture-proof packaging bag dries the material to a moisture level of less than 700ppm and further dries the material to 100-400 ppm. This drying method using only a drying agent is superior to the dry box method in that it does not require special equipment, and dries faster, cheaper, and safer than a dry box. Suitable Tri-Sorb molecular sieve desiccant formulations include: zeolite, NaA; zeolite, KA; zeolite, CaA; zeolite, NaX; and magnesium aluminum silicate, and the like.

After the pod 184, which still has a significant amount of available filaments, is wetted, the formed material filaments may be re-dried by a drying oven or by placement of a desiccant. The material may be wet in some instances, for example, if the chamber door 250 is not closed for a long period of time, if the cartridge 184 is removed from the machine 180 without replacing the plunger cap 248, or if the user opens the cartridge 184, etc.

Fig. 18-19 show in detail the configuration of the pod receptacle 190 that mates with the pod 184. Each pod receptacle 190 includes a lid 270 and a drive module 272. As shown in fig. 19, the drive module 272 includes an inlet conduit 274, an outlet conduit 276, a pair of rollers 278 and 279, a motor 280, and a catch 196. Roller 278 is a drive wheel and roller 279 is an idler wheel. The drive wheel 278 is driven by a motor 280. The motor 280 is preferably a dc motor, the current of which is controlled by the controller 25. The motor 280 traverses through the drive module 272 and engages the drive roller 278 via a drive gear 282 mounted on the shaft of the roller 278.

The outlet pipe 276 is connected to the conduit 202. The filaments supplied by the guide module 214 are fed through inlet conduit 274 to rollers 278 and 279. The inlet conduit 274 cooperates with the outlet 238 of the guide module 214 when the cassette 184 is loaded and locked into the molding machine 180. To provide an airtight path for the filaments entering the drive module 272, the sealing strip 184 wraps around the inlet conduit 274 and presses against the guide module 214 of the loaded filament cassette 184. The filaments are fed by rollers 278 and 279 to outlet duct 276 and thence to conduit 202. The conduit 202 forms a sealed connection with the outlet pipe 276. Similarly, the conduits 202 and 204 form a sealed connection with the openings 198 and 200 of the connection module 192 to provide a sealed path for the filaments from the filament magazine 184 to the feed roller 22.

The drive roller 278 and idler roller 279 must be in close proximity to each other to feed the filament along the channel by friction with the filament. To grip the filaments, the rollers 278 and 279 have resilient surfaces or the idler wheel 279 is spring biased toward the drive wheel 278 as described in U.S. Pat. No. 5,121,329. The spring biased structure has the advantage that the roller may have a hard surface, thereby improving its wear resistance. Preferably, the periphery of rollers 278 and 279 has a grooved configuration so that filaments can be fed from inlet conduit 274 to outlet conduit 276 in the grooves. The rollers 78 and 279 are accessible and accessible for maintenance by a user through the cover 308.

Drive module 272 also includes a filament sensor 286 disposed along the filament path between roller pairs 278 and 279 and outlet conduit 276. Sensor 286 is electrically connected to controller 25 and provides a signal indicating whether a filament is present at the location of sensor 286. In the described embodiment, the sensor is a suspended shaft microswitch sensor. The drive module 274 also carries an electrical connector 290. The electrical connector has two electrical contacts 142 that correspond to the electrical contacts 106 of the circuit board 102 to connect the EEPROM96 on the circuit board 102 to the controller 25. After connection through the connector 142, the EEPROM96 may signal the controller 25 that the cassette 184 is present. Thus, the model forming machine 180 can determine whether the wire magazine 184 is loaded.

The user may manually raise or lower the drive module 272 via the catch 196. The catch 196 has a handle 291 at one end and a catch 292 at the other end. The catch 196 extends through the drive module 272 and is configured such that the user operates the handle 291 and the catch 292 extends into the vertical channel 296 of the drive module 272. The channel 296 receives a locking plate 294 that extends vertically downward from the upper cover 270. The locking plate 294 has an opening 298 for receiving the locking tab 292. The catch 292 is inserted into or withdrawn from the opening 298 by manipulation of the catch 292 by the handle 291 of the catch structure 196. When the catch 292 is inserted into the opening 298, the drive module is in its raised position and the pod can be loaded into the loading bay 182 or unloaded from the loading bay 182; when the catch 292 is pulled out of the opening 298, the drive module is lowered to its lowered position, locking the pod cartridge 184 in the loading bay 182. The user can raise or lower the drive module 272 manually by pulling the catch handle 291 forward to move the catch 196 up or down.

A pair of guide rods 302 are provided on the drive block 272 and function to couple the drive block to the cover 270 and to align the lock plate 294 with the channel 296. Guide rods 302 are mounted in two sockets 288 on the upper surface of drive module 272. Guide rods 302 extend upwardly from the drive module 272 through a pair of guide bearings 304 in the upper cover 270. A pair of E-shaped catch plates 306 are provided on the top cover to catch on the guide rods 302 to provide support for the lower drive module 272. Preferably, a pair of springs 300 encircle the guide rods 302 in the socket 288. In the raised position of the module, the spring 300 may press down on the upper cover 270. When the catch structure 196 is pulled to move the catch 292 out of the opening 298, the force of the spring lowers the drive module 272 to its lower position.

Drying system 194 can establish a moisture barrier along the filament path to keep the filaments in machine 180 in a dry environment. In the illustrated embodiment, the drying system 194 is a dry air cleaning system that injects pressurized dry air into an inlet 199 of the communication module 192. The dry air flows through conduit 204 and exits conduit 204 at an outlet near liquefier 26. If roller 22 is used to feed filaments to liquefier 26, the filaments will be fed to feed roller 22 by conduit 204. Alternatively, feed roller 22 may be defaulted, and roller pair 278 and 279 in drive module 272 employed to feed filaments at a controlled rate to liquefier 26. The outlet of the conduit 204 may act as a vent through which moisture that may be contained in the filament path may be vented. For example, when the inlet conduit 274 of the drive module 272 is not sealed to the filament cassette 184, moisture may enter the drive module 272 and the flow of dry air provided by the drying system 194 may scavenge the incoming moisture. In addition, the positive pressure maintained in the conduit 204 prevents moisture from entering the open port of the conduit 204. By maintaining a positive pressure in conduits 202 and 204 and removing moisture from the filament path, drying system 194 allows the molder 180 to operate in a wet environment and use moisture sensitive molding materials.

As described above, the drying system 194 in the illustrated embodiment includes a compressor 206, a filter 208, and a regenerative dryer 210. The compressor 206 draws in ambient gas and provides the gas at pressure to the filter 208. The filter 208 may filter out moisture in the gas. Norgren can be used here^TMF72G general filter. The pressurized gas stream flows from filter 208 to dryer 210. dryer 210 is preferably of the regenerable type, such as the MDH series dryer available from Twin Tower Engineering, Inc. (Colorado Broomfield). Pressurized drying air flows from the dryer 210 into each of the communication modules 192. In another embodiment of the drying system, a source of drying air under pressure is used to effectively remove moisture from the filament path, although other drying gases may be used. It is important that the drying system is capable of continuously supplying drying air or other gas under pressure to the filament path to prevent moisture from entering the path and to scavenge moisture already in the path, and to enable the gas to be continuously discharged at or near the end of the filament path. In a drying system 194, a nitrogen tank with pressure is used as the drying gas source. In another embodiment of the regenerative drying system, a hot air dryer is employed having an output dew point less than or equal to 40 degrees below zero Fahrenheit.

To load a filament cassette 184 into the molder 180, the machine 180 is first operated. The user then removes the plunger cap 248 from the cartridge 184 and quickly inserts the cartridge 184 into one of the loading compartments 182. The plunger cap 248 may be placed over the groove 256 of the guide module 214 for later use. As previously described, the magazine 184 is locked in place by pulling the catch 196. Once in the locked position, the contacts 142 are connected to the circuit board 102, thereby connecting the EEPROM96 to the controller 25. The controller 25 senses that a filament cassette has been loaded and immediately causes the motor 280 to rotate, thereby causing the drive roller 278 to begin rotating.

Next, the user opens the door 250 of the guide module 214 to operate the roller 240, and rotates the roller 240 by applying a downward force thereto. Rotation of the roller 240 will cause the filament to be fed from the guide module 214 into the inlet conduit 274 of the drive module 272. As the filament is fed to the rotating roller 278, the roller pairs 278 and 279 will grip the filament and take over the task of feeding the filament from the crowded area. At this point, the user quickly closes the door 250 to seal the filament path. The rollers 278 and 279 continue to feed the filament at least to the location where the filament sensor 286 is located. If the magazine 184 is an auxiliary magazine, the controller 25 will signal the motor to stop rotating, thereby interrupting the feed of filament at sensor 286. If the filament cassette 184 is the primary cassette, roller pair 278 and 279 will continue to feed filaments through communication module 192 to feed roller 22 (or liquefier 26). When the filament reaches the infeed roller 22, the infeed roller 22 takes over control of the filament feed. If the current to the motor 280 is set relatively low and the stiffness of the filament is sufficiently high, the motor 280 may continue to operate and maintain a constant feed force; but when the feed roller 22 is no longer rotating, the motor will stop. In this way, the problem of frequently starting and stopping the motor 280 to coordinate synchronization with the infeed roller 22 is avoided. In another embodiment, the roller pairs 278 and 279 may function as a material feed for the feed rollers 22. In this case, the controller 25 closely controls the operation of the motor 280 so that the feed rate to the spinneret 20 can be controlled.

During the molding process, the controller 25 monitors the amount of filament present in each filament magazine by means of the metering device of EEPROM 96. When the main wire box 184 runs out of wire, the model forming machine 180 will automatically turn to the auxiliary wire box 184 without interruption. To unload the filament cassette, the controller 25 causes the motor 280 to move backward for a period of time during which the filament can be drawn from the liquefier 26 and feed roller 22. Controller 25 then rotates motor 280 backward, drawing the filament back through catheter 204, communication module 192, catheter 202, and sensor 286. When the sensor 286 of the primary pod drive module 272 indicates that no filament is present, the machine 180 knows that the communication module 192 is empty and available to receive a filament from the secondary pod 184. The machine then loads the filaments of the auxiliary filament magazine and feeds them to the spinneret 20. This automatic loading and unloading feature is particularly advantageous when used to build large model structures and the model forming machine 180 is operated during times other than working hours. The user may replace the spent filament magazine 184 with new filament for re-use as the machine 180 continues to operate and build the model structure.

When a user wishes to remove the filament from the machine 180 before the filament magazine 184 is depleted, the user may instruct the machine to run an unloading process. If there is still filament available in the filament cassette 184 removed from the machine, the cassette can be stored to prevent contamination for later use. In this case, the user seals the outlet 238 with the plunger 248. If a certain amount of usable filaments 188 remain in the magazine 184 but they are contaminated, the magazine 184 may be redried as described above.

As disclosed in U.S. patent No. 5,866,058, when building a pattern from a thermoset material, it is preferred to form the pattern in a chamber that is heated above the curing temperature of the modeling material and then gradually cool to relieve the material stresses. Many thermoplastics suitable for use as molding materials-such as polycarbonate, polycarbonate/ABS blends and Ultem^TMEtc. -have higher melting points and moisture sensitivity. U.S. PCT application No. US00/17363 discloses an apparatus particularly useful for constructing models at high temperatures.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that additions, deletions, and modifications in form and detail may be made without departing from the scope and spirit of the invention. For example, many structures and characteristics in embodiment 1 and embodiment 2 may be combined and converted to each other, the drying system in embodiment 2 may be used in embodiment 1, the main and auxiliary filament cartridges described in embodiment 2 may be included in the structure of embodiment 1, and the like. In addition, the filament magazine and loading system of the present invention may also be used for feeding filaments in other applications of the spinning process and is not limited to building three-dimensional models, as will be apparent to those skilled in the art. Various other modifications and alterations may also be made within the scope and spirit of the present invention. For example, the motor for driving the wire magazine roller may also be carried by the wire magazine and not necessarily mounted on the mold forming machine. The above and other modifications and variations which may be made will be apparent to those skilled in the art.

Claims (22)

1. A filament cassette, the filament cassette comprising:

a dry, air-tight chamber for receiving a rotatable spool around which said forming filament is wound that is flowable when heated;

a sealed filament path from said chamber to the outlet;

feeding means for feeding the filament from said spool through said passage; and

a barrier preventing air from entering the chamber;

wherein the filament magazine is used to provide formed filaments to a three-dimensional forming machine.

2. The filament cassette of claim 1, wherein the feeding device comprises:

a pair of rollers disposed opposite each other on both sides of the filament path for holding the filament therebetween.

3. The filament cassette according to claim 2, wherein each of the pair of rollers is passive, and one of the pair of rollers is a driven roller that receives an external driving force.

4. The filament magazine as set forth in claim 3 wherein the driven roller has a floating axis of rotation in a direction perpendicular to the filament path, the driven roller being capable of moving away from the filament path in the absence of an external force to release the pressure on the filament in the filament path.

5. The filament magazine of claim 1 wherein the feed means includes an embossing roller mounted opposite the wall of the filament channel so as to grip the filament therebetween.

6. The filament cassette according to claim 5, wherein the embossing roller receives an external driving force.

7. The filament magazine of claim 1 wherein the feed mechanism includes a raised profile for receiving the filament material in the wall of the filament channel, the application of the pushing force being applied to the filament above the profile.

8. The filament cassette of claim 7, wherein the raised profile is defined by a surface of an idler wheel.

9. The filament magazine of claim 1 wherein the means includes a retainer for retaining the filaments in the filament path and preventing air from flowing along the filament path.

10. The filament cassette of claim 1, wherein the means comprises a door through which the feeding means can pass.

11. The filament cassette of claim 1, wherein the chamber and wound filament material are dried to a moisture content of less than 700 ppm.

12. The filament cassette of claim 1 further comprising a desiccant disposed within the chamber.

13. The filament cassette of claim 1, further comprising a readable and writable data storage device mounted on the filament cassette, the device containing information about the filament and being electrically connected to an external controller.

14. The pod of claim 1, wherein the blocking device comprises a removable seal positioned over the outlet.

15. The filament cassette of claim 1 further comprising a cavity for aligning the cassette with a cassette receiver of a molding machine. .

16. A method of using the filament cassette of any of claims 1-13 to provide formed filament material to a three-dimensional forming machine, the method comprising the steps of:

inserting the filament box into a filling cabin of the forming machine;

a strand of filament clamped in the filament channel of the filament cassette; and

the filament material is fed out of the filament magazine outlet into the former tube.

17. The method of claim 16, further comprising the steps of: air is prevented from flowing into the chamber as the filaments exit the cartridge.

18. The method of claim 16, further comprising the steps of: determining that the retained filament material in the filament magazine has reached a predetermined minimum length;

in response to the minimum length confirmation signal, the filament material is automatically withdrawn from the conduit so that the filament magazine can be removed and replaced.

19. A method of assembling a filament cassette according to any one of claims 1 to 13, the method comprising the steps of:

providing a filament magazine comprising a chamber, a filament path from the chamber to an outlet and means for feeding filament along the filament path;

loading a rotatable spool wound with a forming wire into a chamber, wherein the forming wire is flowable when heated; drying the chamber and the wound strand; and

the box is sealed after loading the wire material to make the chamber airtight.

20. The method of claim 19, wherein the drying step further comprises placing a desiccant in the chamber.

21. The method of claim 19, wherein the drying step further comprises heating the filament cartridge in a drying oven under vacuum conditions to a moisture content of less than 700ppm prior to the sealing step.

22. The method of claim 19, wherein said filament is made of a high temperature thermoplastic material.