Abstract: Disclosed are a filament cassette and a filament loading assembly for supplying filament in a three-dimensional deposition modeling machine. The filament cassette contains a rotatable spool of filament, and has an exit orifice through which a filament strand may exit the cassette. The filament loading assembly is mounted on the modeling machine and receives the filament cassette. The filament loading assembly has conduit for receiving a strand of filament from the cassette and a drive means for advancing the filament strand through the conduit. The filament cassette and loading assembly of the present invention provide a convenient manner of loading and unloading filament from the modeling machine. The filament cassette and the conduit may be made airtight so that the filament is protected from moisture in the environment.

Abstract: Formation of polymeric prototype elements is effected by high pressure and high temperature extrusion of selected materials onto a plate as a ribbon of liquefied polymer comprising poly(2-ethyl-2-oxazoline) and a polar polymer discharged in a programmed pattern.

Abstract: An electrically operated apparatus and method for altering the flow resistance experienced by a thermoplastic passing through a flow channel using one or more thermal valves having a short response time is described. The extrudate configuration of thermoplastic emerging from one or more extrusion orifices is alterable by selectively opening one or more of thermal valves that supply thermoplastic to the one or more extrusion orifices. Each thermal valve is cooled by a heat sink and has an associated heater responsive to control signals. Each heater is independently activated in synchronization with movement of the apparatus in a predetermined spatial pattern with respect to a base. By extruding thermoplastic onto a base layer-by-layer in this manner, a three-dimensional object may be formed.

Abstract: Formation of polymeric prototype elements is effected by high pressure and high temperature extrusion of selected materials onto a plate as a ribbon of liquefied polymer comprising poly(2-ethyl-2-oxazoline) and a polar polymer is discharged in a programmed pattern.

Abstract: A volumetric feed control apparatus for a build material element such as a filament used in a three-dimensional modeling machine having an application tip includes a pair of feed rollers feeding the filament to the application tip, and a sensor or sensor system feeding information to a central processing unit that continuously computes the effective cross section of the filament using the signals received from the sensor or sensor system. The central processing unit controls the speed of a DC servo or stepper motor which in turn rotates the feed rollers to advance the filament toward the application tip of the modeling machine. The central processing unit adjusts the speed of the feed rollers to supply a constant flow rate of material to the application tip. Alternatively, the sensor system can be incorporated into the feed rollers, eliminating the need for further space constraints.

Abstract: A water-soluble thermoplastic composition for three-dimensional modeling comprising poly(2-ethyl-2-oxazoline) is disclosed. The composition in the form of an extrudable object may be extruded by an extrusion apparatus in a programmed pattern onto a base as a ribbon of liquified polymer to create a support structure for a prototype object or to create a water-soluble polymeric element.

Abstract: An apparatus for thermal extrusion of a polymeric material to manufacture prototype mechanical elements from said polymeric material, said apparatus used for deposition of a liquefied ribbon of said polymeric material in patterned layers which solidify to form a three-dimensional prototype element, said apparatus comprising in combination, a mounting frame, said mounting frame including a mounting plate with a movable platen movable in the x and y directions, said frame further including an extrusion cylinder, said extrusion cylinder comprising a cylindrical housing having a uniform diameter cylindrical through passage, a head member having a uniform diameter bore connected with a reduced diameter, integral tip opening, said head member attached by a clamp to one end of the cylindrical housing to align the bore with the through passage, said-bore and through passage having an equal diameter, said head member including a circumferential heater to liquefy contents of the head member, a reciprocal piston slidabl

Abstract: An apparatus has an extrusion head for extruding a bead of a liquified material at an extruded pump flow rate, an extrusion head motor for driving the extrusion head at a variable head velocity, a pump for providing liquified material to the extrusion head, and a control for providing control signals to both the extrusion head motor and the pump. The control signals control operation of the extrusion head and the pump so that the head velocity is slaved to an estimated profile of the extruded pump flow rate divided by a predetermined bead cross-sectional area.

Abstract: The present invention provides a method for controlling following error in a robotic system that moves a tool at a velocity along a path defined by an inputted set of vertices. The following error is controlled to be less than a tolerable error allowance. First, a subset of resonant vertices is identified from the inputted set of vertices. Each of the resonant vertices has a neighboring vertex for which a following error that results when the tool negotiates both the vertex and its neighboring vertex at an assigned vertex velocity might exceed the tolerable error allowance. Second, each vertex in the subset of resonant vertices is assigned a reduced vertex velocity. The reduced vertex velocity is selected so that the following error that results when the tool negotiates both the vertex and its neighboring vertex at the reduced velocities is less than the tolerable error allowance.

Abstract: A filament spool used in a rapid prototyping system carries a circuit which maintains data regarding the type and amount of filament on the spool. When the spool is mounted onto a spindle in the rapid prototyping system, the circuit is connected to the electronic control of the system. The data indicating the electronic control of the system. The data indicating the amount of filament on the spool is updated as filament is used by the system.

Abstract: A rapid prototyping system has a liquifier carried by a extrusion head. The liquifier is formed of a single piece of thin-wall tubing preferably made of metal, encased in a heating block. The thin-wall tube has a inlet end for receiving a filament of molding material and an outlet end for delivering the material in liquid form. A first section of the tube adjacent the inlet end functions as the entrance or cap zone. This first section of the tube is exterior to the heating block. The tube has a second section which passes through the heating block forming a heating zone. A nozzle can be formed by swaging the outlet end of the tube to a nozzle geometry, or, a nozzle may be brazed or welded to the outlet end of the tube. The heating block preferably contains a heating element in heat exchange relation to the second section of the tube to heat the filament to a temperature just above its solidification temperature.

Abstract: A rapid prototyping system forms three-dimensional objects by depositing layers of material on a substrate. A planer stator containing a grid of stator elements is positioned above and generally parallel to the substrate. An extrusion head is magnetically suspended below the stator and is separated from the stator by an air bearing. An electromagnetic drive receives control signals from moving the extrusion head relative to the grid of stator elements. An umbilical provides mechanical damping to the head to reduce resonance of the head during movements.

Abstract: A rapid prototyping system makes three-dimensional objects by sequentially depositing multiple layers of solidifying material on a flexible sheet substrate. The substrate is held against the top surface of a vacuum platen during deposition of the layers. When the object is completed, the substrate is released from the vacuum platen. By flexing the substrate, the object is peeled away from the substrate.

Abstract: A fused deposition process is used to form three-dimensional solid objects from a mixture including a particulate composition dispersed in a binder. The article is formed by depositing the mixture in repeated layers of predefined thickness, with each layer solidifying before the next adjacent layer is dispensed. Following formation and a binder removal step, the article may be at least partially densified to achieve preselected properties. The process permits three-dimensional articles to be formed relatively quickly and inexpensively, without the need for molds or other tooling.

Abstract: Data corresponding to a desired shape of a prototype is transmitted to a rapid prototyping system. The system calculates a sequence for extruding flowable material that thermally solidifies so as to create the desired geometric shape. A heated flowable modeling material is then sequentially extruded at its deposition temperature into a build environment that maintains the volume in the vicinity of the newly deposited material in a deposition temperature window between the material's solidification temperature and its creep temperature. Subsequently the newly extruded material is gradually cooled below its solidification temperature, while maintaining temperature gradients in the geometric shape below a maximum value set by the desired part's geometric accuracy.

Abstract: An improved extrusion-based manufacturing system includes one or more extruders, with each extruder containing at least two stages of increasing pressurization. In a preferred embodiment, a first stage of pressurization is created by the motion of a solid wafer of thermoplastic through an orifice into a heater chamber. In another preferred embodiment, the wafers are stored in removable, electronically tagged, cassettes and are removed therefrom by a stapler mechanism which feeds the wafers from the cassette to a tractor feed mechanism on demand. In each embodiment, a second stage of pressurization is provided by a pump, with the first stage pressurization maintaining a flow of thermoplastic to the pump under all expected pump rates.

Abstract: A method of making a three dimensional object by depositing material in a predetermined pattern on a receiving surface, and introducing a predetermined porosity into the object being formed by positioning the deposited material so as to introduce pockets of air or other fluid into the part, and by adjusting the rate at which the material is dispensed from the dispenser. Optimal porosities in the object to be built depend upon the shape of the material when it is dispensed, but range generally from 1% to 26%.

Abstract: Beginning with a CAD specification of an object, the method and apparatus of the invention reduces the overall time to produce a shell of the object with a rapid prototyping machine. The reduction in time is achieved by interleaving the computation and the building tasks and by not requiring an explicit evaluation of a shell of the solid at the outset. The method is shown to operate with STL data, or with other CAD data, directly, and can also be employed to create non-planar objects, such as models of sheet metal parts that are represented only as surfaces. Furthermore, the method can be employed to produce a smooth outer surface even when employing polyhedral approximations to the surfaces of the object.

Abstract: Processes and apparatus are disclosed for producing three-dimensional objects having overhanging portions freely suspended in space without any material of the object in direct, supporting engagement therewith in the final geometry of the object. A support structure is formed by depositing material which will be under the ultimately suspended portions of the object to be formed, during a process in which material is built up in layers to form the object as well as the underlying support structure. A readily removable support structure is formed along an interface with the underside of the suspended portion of the object structure. A weak, removable or breakable joint is formed along that interface by the use of an interface material which forms a weak or dissolvable bond with the material of the object. The release material may be deposited as a separation layer, or as a thin coating.