Freeform fabrication techniques are particularly useful for reducing the design, production and maintenance cycle times associated with the manufacture of three-dimensional objects. In the design phase, freeform fabrication techniques are especially useful for refining prototyping designs, investigating inconsistencies in designs, and modifying designs prior to full-scale production. In addition, freeform fabrication techniques have been shown to yield higher quality products at lower cost.
However, the need presently exists for improved freeform fabrication techniques capable of producing complex structures at lower cost with minimum set-up and run-times. Although widely known, conventional freeform fabrication techniques remain mostly inadequate for low-cost production of complex three-dimensional structures. See e.g. J. J. Beaman, J. W. Barlow, D. L. Bourell, R. H. Crawford, H. L. Marcus and K. P. McAlea, "Solid Freeform Fabrication: A New Direction in Manufacturing," ch. 2 (Kluwer Academic, Norwell, Mass., 1997).
One such technology, wire-like filament deposition, has emerged as a popular freeform fabrication technology for forming three-dimensional solid components. The most widely known filament deposition system is the Fused Deposition Modeling ("FDM") system developed by Stratasys, Inc. See P. F. Jacobs, Rapid Prototyping & Manufacturing Fundamentals of Stereolithography, pp. 406-409 (Society of Manufacturing Engineering, Dearborn, Mich., 1992). The FDM system deposits a continuous filament of a thermoplastic polymer or wax through a resistively heated, x-y position controlled nozzle or delivery head. The material is heated just above its melting temperature and then deposited into thin layers, on a layer-by-layer basis, on top of a fixture-less base. As the object is built upwards on the base, the thermoplastic or wax material solidifies in place to form the desired three-dimensional components.
However, because of the fixed-size head, the manufacturing and prototyping capabilities of the FDM system is severely limited due to the size of the extruded filaments. At best, the filaments are limited to a relatively small range of sizes and thus the total mass flow rate of the filament deposition is severely limited. As such, the FDM system is inadequate for large-scale manufacturing and complex rapid prototyping.
Therefore, a principal object of the present invention is to provide a system for producing variable-diameter filaments of forming materials that can be efficiently and accurately deposited on a substrate based on the specific outline geometry and internal micro-structure of the three-dimensional object to be formed.
Another object of the present invention is to provide a system for forming three-dimensional objects wherein variable-diameter filaments of forming materials are selectively deposited in an incremental manner on a position controllable substrate.
Still another object of the present invention is to provide a system for manufacturing high quality three-dimensional objects at low cost with minimum setup and run-times.
Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the invention.