Stock material or miscellaneous articles – Structurally defined web or sheet – Nonplanar uniform thickness material
Reexamination Certificate
1998-07-08
2001-04-24
Loney, Donald (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Nonplanar uniform thickness material
C261S112100, C261SDIG007, C210S660000, C165S060000, C165S158000, C055S440000
Reexamination Certificate
active
06221463
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to three-dimensional structures formed from plastic films. More particularly, the present invention is directed to a method of transforming flat films into a select three-dimensional structural sheet, the structural features of the formed sheet, and the structures and apparatus available by assembling the formed sheets in a select manner.
Disclosure Document Nos. 423444 and 429903 were filed on Aug. 20, 1997 and Jan. 2, 1998, respectively. The contents of these Disclosure Documents are incorporated herein, as if restated in full.
BACKGROUND OF THE INVENTION
There has been a large effort to create unique materials having defined engineering properties for use in a wide variety of products. These materials are targeted at increasing certain functional characteristics, such as strength, or porosity, while minimizing cost and/or weight. Other desirable properties include durability, light transmissivity, corrosion resistance, and the like. Fundamental structures have been created that impart valuable properties to select products. For example, the “honeycomb” structure provides a high strength to weight ratio that has found broad application in demanding designs.
Another example is the porous minimal surface structures used as a bone substitute and other select medical applications. The present inventor is responsible for developing such a specialized material, described in U.S. Pat. Nos. 5,348,788 and 5,455,100, the contents of which are incorporated by reference as if restated in full. These structures provide a highly innovative solution to the difficult process of emulating a mathematically periodic minimal surface to impart select functional characteristics to the product at issue.
These patents and the associated technology, however, are focused on medical applications which have a narrow field of use and a rigid requirement definition. In this context, applications of fundamental minimal surface constructs are far more extensive and include:
1. Heat exchangers,
2. Catalytic converters,
3. Kiln furniture,
4. Photonic devices (including photonic band gap material),
5. Composite smart materials, and
6. High strength/weight materials.
Recognizing that this potential universe is largely unaddressed by current technology, the present inventions were developed to meet this need.
OBJECTS AND SUMMARY OF THE PRESENT INVENTION
It is, therefore, an object of the present invention to provide a structured three-dimensional film having select properties.
It is another object of the present invention to provide a method for creating a thin film having a select collection of structural properties including a three-dimensional periodic minimal surface.
It is yet another object of the present invention to provide a three-dimensional, semi-rigid film having a regular pattern of depressions and raised portions defining a select surface structure.
It is another object of the present invention to provide multiple films individually formed into select three-dimensional structures that are then layered to create a specific structural element having low density and a high strength to weight ratio.
It is a further object of the present invention to provide three-dimensional structures that allow for efficient heat exchange between two fluids brought into thermal contact by opposing networks formed throughout the three-dimensional structure.
It is yet another object of the present invention to provide a method of forming thin film, three-dimensional structures wherein the film is made from plastic material such as polyethylenes, PET (Mylar), polycarbonate (Lexan®), copper, brass, gold, and/or platinum.
It is a further object of the present invention to provide a mechanism to create selectively shaped films with regular surface characteristics.
It is yet another object of the present invention to provide a mechanism for creating a continuous web of three-dimensional film having a uniform pattern of depressions and raised portions.
The above and other objects of the present invention are realized in an illustrative thin film, three-dimensional structure having a matrix of depressions and raised portions at select intervals across the film surface. The film is formed by taking a thin sheet stock, initially flat, and placing it between opposing offset arrays of pins that are precisely aligned in two parallel plates. The process provides for deforming the films between the opposing pins by bringing the plates together, with the resulting tensile forces on the film creating a corresponding network of opposing depressions at regularly spaced intervals. Upon release from the opposing pins, the film retains the deformations created by the pins at the selected intervals, thus forming a three-dimensional structure with a tightly controlled matrix of depressions and raised portions. In addition, the uniform deformation forces applied to the film create a structure characterized by an approximate minimal surface (e.g., a saddle-shaped contour) between the depressions and raised portions.
The opposed array of pins are configured to have a uniform height across the array with each pin having a flat circular top surface. The flat top surface translates to a corresponding depressed circular flat in the deformed sheet. This flat region permits good adhesive contact between multiple sheets when layered together to construct a larger structure. The opposed array of pins are individually held in two flat metal plates by press-fit at the select height. The flat plates are placed in parallel alignment during the forming process, with the opposing pins arranged in parallel, but offset in a symmetrical manner to provide the alternating matrix of depression and raised portions in the film placed therebetween.
In accordance with the varying objectives of the present invention, the three-dimensional thin film structures are stacked with corresponding flattened peaks aligned to form points of adhesion. The resulting multi-layer structure creates a porous network of passages, separated by the minimal surface of the film. This network of passages is arranged in one configuration, to provide for at least two fluid chambers and passageways to permit enhanced heat exchange between the fluids. The chambers formed by the layer films may be selectively interconnected by opening one or more of the depressions or raised portions. In addition, the multi-layered structure formed by the above process provides significant rigidity and strength at a very low corresponding weight. This provides a high strength to weight ratio and thus a very useful structural support component.
The foregoing features of the present invention may be better understood by review of the following description of an illustrative example thereof, taken in conjunction with the drawings of which:
REFERENCES:
patent: 3227598 (1966-01-01), Robb
patent: 3388522 (1968-06-01), Lowes
patent: 3876492 (1975-04-01), Schott
patent: 3938963 (1976-02-01), Hale
patent: 3940811 (1976-03-01), Tomikawa et al.
patent: 5266379 (1993-11-01), Schaeffer et al.
patent: 5348788 (1994-09-01), White
Hopgood, Calimafde, Judlowe & Mondolino LLP
Loney Donald
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