Metal founding – Means to shape metallic material
Reexamination Certificate
1998-01-22
2001-04-17
Lin, Kuang Y. (Department: 1722)
Metal founding
Means to shape metallic material
C164S046000, C075S335000
Reexamination Certificate
active
06216765
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to an apparatus and method for manufacturing a three-dimensional object. According to the apparatus and methods of the present invention, continuously variable diameter or controllable planar jets are used to form three-dimensional objects in an environment-controlled processing chamber. The apparatus and methods of the present invention are useful in the fields of rapid prototyping and materials processing.
Manufacturing processes utilizing deposition techniques have been developed for rapid and flexible prototyping of three-dimensional parts and tooling. For example, U.S. Pat. Nos. 5,301,863, 5,301,415, 5,207,371 and 5,286,573 to Prinz et al. disclose conventional systems and methods for manufacturing three-dimensional objects by forming incremental buildup of layers on a work surface. In preferred embodiments of these inventions, thermal spray or weld deposition techniques are used to deposit object and support layers on a work surface.
Drop generators have also been developed and applied to the rapid prototyping of three-dimensional objects. See P. F. Jacobs,
Rapid Prototyping and Manufacturing,
ch. 16 (Society of Manufacturing Engineers, Dearborn, Minn. 1992). In a conventional drop generator of this type, molten metal is ejected as a uniform laminar liquid jet from a circular injector, or nozzle, located at the bottom of a heated reservoir. The uniform laminar liquid jet is broken into a series of uniform drops of desired size by selecting an injector diameter and varying the frequency of external oscillation near the injector or nozzle orifice. The uniform drops are then deposited in layers on a substrate surface where they solidify to form the desired three-dimensional metal product.
With this technique, the resulting metal products can be designed to have fine, equiaxed micro-structures without manufacturing defects such as porosity or alloy segregation. See C. -A. Chen, P. Acquaviva, J. -H. Chun and T. Ando, “Effects of Droplet Thermal State on Deposit Microstructure in Spray Forming”,
Scripta Materiala,
vol. 34, pp. 689-696 (1996); J. -H. Chun and T. Ando, “Thermal Modeling of Deposit Solidification in Uniform Droplet Spray Forming,”
Proceedings of the
1996
NSF Design and Manufacturing Grantees Conference,
pp.353-354 (Society of Manufacturing Engineers 1996). This allows for a rapid one-time process for metal forming that does not require expensive and time-consuming post-processing of metal products.
However, despite these advantages, the manufacturing capabilities of conventional drop generators remain limited by the relatively small range of possible drop sizes. Greater variability in the drop size is desired to allow more efficient rapid prototyping by allowing the mass flux to be set according to the outline geometry and desired internal micro-structure of the product at a given point. Despite the variability of external oscillation, the possible range of drop sizes from a conventional drop generator is limited by the fixed injector diameter, which is typically less than one millimeter. Consequently, the liquid jet of a conventional drop generator remains laminar.
Therefore, a principal object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a continuously variable diameter liquid jet to create variable drop sizes.
Another object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a controllable laminar planar liquid jet to form a liquid sheet and create arrays of uniform molten metal drops.
A further object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a piezoelectric oscillator and piezoelectric transducer circuit for creating continuously variable diameter and controllable planar jets.
Yet another object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a position controllable platform.
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.
SUMMARY OF THE INVENTION
The present invention is an improved apparatus and method for manufacturing a three-dimensional object whereby a sequence of molten metal drops is deposited on a substrate to create the three-dimensional object. In accordance with a preferred embodiment of the present invention, the apparatus includes a crucible for holding molten metal, an orifice disposed in the bottom of the crucible through which a jet of molten metal flows towards the substrate, and a mechanically oscillating member immersed in the molten metal for controlling the flow of molten metal through the orifice and for breaking the flow of molten metal into the sequence of molten metal drops.
According to further embodiments of the present invention, the molten metal flowing from the crucible orifice is formed to be a continuously variable diameter jet or a controllable laminar planar jet. The continuously variable diameter jet is useful for producing a wide range of drop sizes. Variability in the drop size allows more efficient rapid prototyping since the mass flux can be set according to the outline geometry and desired internal micro-structure of the product at a given point. The controllable laminar planar jet is useful for large-scale drop forming processes.
The apparatus of the present invention also includes a position controllable platform for positioning a traversable substrate element whereupon the desired three-dimensional object is formed. Advantageously, the position controllable platform is operated and controlled by a computer, position controller device, interface and corresponding software.
In accordance with another aspect of the present invention, a method for manufacturing a three-dimensional object is provided whereby a sequence of molten metal drops is deposited on a substrate to form the three-dimensional object. The method for manufacturing a three-dimensional object includes the steps of depositing molten metal in a crucible; ejecting the molten metal through on orifice disposed in the bottom of a crucible to form a jet of molten metal that flows towards the substrate; and actuating a member immersed in the molten metal to control the flow of molten metal through the orifice and to break up the flow of molten metal into the sequence of molten metal drops. According to further aspects of the invention, the method utilizes a continuously variable diameter jet or a controllable laminar planar jet.
REFERENCES:
patent: 5061454 (1991-10-01), Birk
patent: 5207371 (1993-05-01), Prinz et al.
patent: 5266098 (1993-11-01), Chun et al.
patent: 5286573 (1994-02-01), Prinz et al.
patent: 5301415 (1994-04-01), Prinz et al.
patent: 5301863 (1994-04-01), Prinz et al.
patent: 5330100 (1994-07-01), Malinowski
patent: 5445666 (1995-08-01), Peschka et al.
patent: 5598200 (1997-01-01), Gore
patent: 5617911 (1997-04-01), Sterett et al.
patent: 5722479 (1998-03-01), Oeftering
“The Aerodynamic Instability and Disintegration of Viscous Liquid Sheets”, N. Dombrowski and W. R. Johns, Chemical Engineering Science, 1963, vol. 18, pp. 203-214, Pergamon Press Ltd., Oxford, Great Britain.*
“The Aerodynamic Instability and Disintegration of Viscous Liquid Sheets”, N. Dombrowski and W.R. Johns, Chemical Engineering Science, 1963, vol. 18, pp. 203-214, Pergamon Press Ltd., Oxford, Great Britain.
“Rapid Prototyping & Manufacturing Fundamentals of StereoLithography”, First Edition, Paul F. Jacobs, Ph.D. Principal Author, Published by Society of Manufacturing Engineers in cooperation with the Computer and Automated Systems Association of SME, 1992.
“Effects of Droplet Thermal State on Deposit Microstructure in Spray Forming”, Chen-An Chen, Paul Acquaviva, Jung-Hoon Chun and Teiichi Ando, Scripta Materialia, vol. 34, No. 5, pp. 689-696, 1996, Elsevier
Lee Tae-woo
Tseng Ampere A.
Arizona State University
Baker & Botts L.L.P.
Lin I.-H
Lin Kuang Y.
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