The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 03, 2002
Filed:
Sep. 27, 2000
Dawn White, Ann Arbor, MI (US);
Solidica, Inc., Ann Arbor, MI (US);
Abstract
Resistance heating, preferably with applied pressure, is used to consolidate incremental volumes of material to produce a desired object in accordance with a description thereof. The joining of the material increments may occur in the solid state, liquid state, or 'mushy' state in conjunction an atomically clean faying surface between the increments without melting the material in bulk. Residual stresses are minimized, particularly in metal objects, by imposing a compressive residual stress on the surface of each deposited layer or increment, which offsets all or a portion of the tensile stress created as the next layer deposited above it cools. In terms of apparatus, a moving cathode is used to ensure uniform electrical current flow in an object with constantly changing geometry. The contact resistance of the interface between the workpieces is preferably continuously measured, and the sensor data is used to update a look-up table, or as input to an adaptive closed loop control system to ensure consistent welding conditions as object geometry changes continually. Also disclosed are embodiments associated with the fabrication of functionally gradient materials.