Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1999-05-11
2001-11-27
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S098000, C264S401000
Reexamination Certificate
active
06324438
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to prototype modeling and construction and, more particularly, to rapid prototype modeling and construction.
BACKGROUND OF THE INVENTION
More and more manufacturers are using rapid prototyping techniques to facilitate bringing products to market with decreasing lead times and development costs. The term “rapid prototyping” conventionally defines automatic techniques for producing a solid three-dimensional object via a computer model. Specifically, a computer model is utilized to produce thin plane cross-sections of a part. These crosssections, or layers, are then used as the building blocks of the prototype part with each of the layers being cut or formed separately.
Rapid prototyping techniques typically start with a computer aided design (CAD) representation or model of a part. The CAD model is then “sliced” graphically into a series of parallel cross sections spaced at a distance equal to the eventual thickness of the physical layers used to make the prototype part. Each physical layer is registered with respect to previous layers, and layers are bonded together via process-specific mechanisms such as melting, gluing, and sintering. For example, U.S. Pat. No. 5,847,958 to Shaikh et al. describes a process for rapidly prototyping a contoured part wherein a three-dimensional CAD model of the part is created and then sectioned into a plurality of graphical slabs. Physical solid members are machined for each graphical slab and then are joined together to replicate the CAD model. U.S. Pat. No. 5,779,833 to Cawley et al. describes a process for creating ceramic parts from a plurality of contoured layers that are separately made and then secured to each other via a sintering process.
There are considerable benefits associated with rapid prototyping. These include: reducing the amount of time required for a product to reach the market; enhancing the ability to perform functional, form and fit testing of a part; and facilitating low cost, small volume production.
Despite these benefits, current rapid prototyping processes suffer from several drawbacks. First, rapid prototyping equipment is quite expensive, with costs typically ranging between $100,000 and $500,000. Another drawback associated with conventional rapid prototyping is the length of time typically required to produce a prototype part. Conventional rapid prototyping techniques can take up to twenty-four hours to produce a single prototype part once a computer model of the part has been created.
A third drawback associated with conventional rapid prototyping is the general inability to produce strong parts that can be used directly in products or assemblies. Most current rapid prototyping processes produce relatively low-strength parts, typically out of paper, wax, or other low-strength materials. Rapid prototyping processes that do utilize stronger materials such as plastics, ceramics, and metals, often suffer from material weakness due to porosity, brittleness, incomplete bonding of layers, and even degradation over time.
Yet another drawback associated with conventional rapid prototyping is the inability to produce parts having accurate and precise geometries. For example, curved surfaces often have a “stair-step” appearance when multiple layers are assembled together. In addition, parts having undercut regions can be difficult to produce via the assembly of multiple layers. This is because it may be difficult to support layers that overhang undercut regions during assembly of the layers.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the present invention to provide rapid prototyping systems and methods that are relatively inexpensive to implement compared with conventional rapid prototyping systems and methods.
It is another object of the present invention to provide rapid prototyping systems and methods that can reduce the length of time required to produce a prototype part.
It is another object of the present invention to provide rapid prototyping systems and methods that can produce strong, functional prototype parts from relatively inexpensive raw materials.
These and other objects of the present invention are provided by methods and apparatus for rapidly prototyping a three-dimensional object from a plurality of layers wherein each layer is cut after being fused with a preceding layer. A computer model of a three-dimensional object is initially created using CAD software. The computer model is then sliced into a sequential plurality of slices. Each slice is a mathematical representation of a corresponding sequential layer of the prototype. Using the computer model slices, machine tool paths for cutting each respective sequential layer from respective sheets of material are generated.
A first sheet of material, such as thermoplastic material, is removably secured to a support structure. A first sequential layer having a peripheral edge and an exposed face is cut from the first sheet using a respective machine tool path generated for the first sequential layer. A solvent is then applied to a face of a second sheet of material. The second sheet of material is placed in contacting face-to-face relation with the first sequential layer such that the solvent fuses the face of the second sheet of material with the exposed face of the first sequential layer. A second sequential layer having a peripheral edge and an exposed face is cut from the second sheet of material along a respective machine tool path generated for the second sequential layer. The above procedure is repeated until all remaining layers of the prototype part are produced.
The peripheral edge of each layer can have various configurations to facilitate producing a contoured surface of a prototype part. For example, the peripheral edge of each layer can have a sloped configuration, an orthogonal configuration, or a stepped configuration relative to a face thereof, or some combination thereof.
According to another embodiment of the present invention, a rapid prototyping system for rapidly producing a prototype of a three-dimensional object from a plurality of layers includes a data processing system and a three-dimensional part generator in communication with the data processing system. The data processing system includes a computer running a CAD software program which is used to create a CAD drawing of the three-dimensional object. Once the CAD drawing of the prototype is complete, the user “prints” (i.e., produces) a three-dimensional prototype via the three-dimensional part generator according to the above-described method.
The present invention is advantageous because inexpensive raw materials available from most plastics suppliers can be utilized to produce strong, functional prototype parts rapidly. Prototype parts constructed according to the present invention can be produced more quickly than prototype parts constructed using conventional prototyping methods. Furthermore, prototype parts constructed according to the present invention can be stronger and more durable than prototypes constructed using conventional rapid prototyping methods.
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Cormier Denis R.
Taylor James B.
West, II Harvey A.
Bahta Kidest
Grant William
Myers Bigel & Sibley & Sajovec
North Carolina State University
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