International Business Machines Corporation

George M Koppelman

John Samuel Batchelder

Douglas S Goodman

Huntington W Curtis

John D Mackay

Robert R Jackson

Franklin Gracer

Vadakkedathu Thomas Rajan

Roger C Evans

Disclosed are methods and apparatus for fabricating a three-dimensional object in accordance with a computer-generated definition of the object that is stored within a memory. A method includes the steps of (a) evaluating the stored definition of the object to locate any un-supported features of the object; in response to locating an un-supported feature, (b) defining a support structure for the un-supported feature; (c) generating a fabrication tool movement list expressive of movements required by a fabrication tool to fabricate the object and any defined support structures; and (d) translating the fabrication tool in accordance with the generated fabrication tool movement list to fabricate the object and any defined support structures. The step of translating includes the steps of, generating a feedback signal that is indicative of at least one characteristic of a most recently fabricated portion of the object; and monitoring the feedback signal to detect a deviation of at least a location of the most recently fabricated portion of the object from a corresponding location as expressed in the associated portion of the fabrication tool movement list. Also disclosed are methods and apparatus for anti-aliasing aliased surface features of the object, representing the object definition in a vector format, generating a bit-mapped representation of the object, and an analysis of the definition of the object to identify and subsequently compensate for a region of the object that has a potential to retain heat during fabrication.

Model generation system having closed-loop extrusion nozzle positioning

Apparatus and method for fabricating a three-dimensional object in accordance with a CAD-generated specification of the object. A closed-loop extrusion system (10) includes a nozzle (12) for extruding a material, such as a hot melt adhesive; apparatus (14, 18, 46) for controllably positioning the nozzle in accordance with the specification; and a sensor (60) for generating a feedback signal that is indicative of at least one characteristic of a most recently extruded portion of the material. Visual and non-visual feedback sensors may be employed, including optical sensors, infrared emission sensors, and proximity detection sensors. The specification of the object is converted to a bit-mapped representation thereof to improve accuracy relative to vector-based representations. Methods for determining a need for supporting structures and anti-aliasing features and for integrating the structures and features into the object specification are also disclosed.

Cumulative translational sweeps are used to shape geometric objects in a computer model, and they permit display of the resulting changes in shape in the object modelled, and control of processes involving the object modelled. If the geometric object is polyhedral, the cumulative translational sweeps, by creating additional facets, effect selective rounding along model edges and around model vertices. This permits computer modelling of the growth of layers, encompassing in addition to flat surface growth, growth with rounding around corners and over obstacles. Such growth occurs in the manufacture of semiconductors. Modelling a change in a solid structure in stages of growth (or shrinking) and of rounding, as might take place during processing of integrated circuits is achieved by controlled sweep sequences that sweep the structure a finite number of times in accordance with a rayset and stipulated parameters of shape, balance, convexity/concavity, degree of faceting, and memory limitation. The cumulative translational sweep (CTS) is applied in combination with Boolean operations to simulate growth and shrinking over the boundary regions of polyhedral models. By creating additional facets, it effects stipulated selective or global rounding effects along model edges and around model vertices. Such sweeps are examined in terms of Minkowski sums--of the geometric objects that are swept, with structuring geometric shapes that are convex polyhedron from the zonotope subclass of the mathematical family of objects known as polytopes.

Shaping geometric objects by cumulative translational sweeps

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New York, NY, United States of America

George M Koppelman