Method and apparatus for fabrication of articles by molten and semi-molten deposition

Abstract

A method and apparatus for depositing metals and metal-like substances in two and three dimensional form without a substrate in a safe, rapid and economical fashion using gas shielded arc welding equipment and programmable robotic motion. The method and apparatus includes the use and application of robotic controls, temperature and position feedback, single and multiple material feeds, and semi liquid deposition thereby creating near net shape parts particularly well suited to rapid prototyping and lower volume production.

I claim: 
     
         1 . An additive manufacturing apparatus to fabricate objects by depositing metal or metal like materials in three dimensions comprising:
 a build table;   a deposition head configured to deposit the metal objects on the build table;   a multi-axis robotic system configured to support the deposition head;   wherein said build table is configured to be adjustably located in a tank;   wherein the quenchant fluid is added to the tank during the build.   
     
     
         2 . The additive manufacturing apparatus of  claim 1  further comprising one or more level sensors maintaining the level of said quenchant fluid. 
     
     
         3 . The apparatus of  claim 1  further comprising a weir_maintaining the level of said quenchant fluid. 
     
     
         4 . The apparatus of  claim 1  further comprising said quenchant fluid being circulated in the tank. 
     
     
         5 . The apparatus of  claim 4  further comprising said quenchant fluid being circulated at a rate sufficient for convective cooling. 
     
     
         6 . The apparatus of  claim 4  further comprising a forced flow heat exchanger to maintain said quenchant temperature. 
     
     
         7 . The apparatus of  claim 6  further comprising a forced flow heat exchanger in a circulating plumbing system. 
     
     
         8 . The apparatus of  claim 1  wherein only the bottom of said platen is submerged at the beginning or during the build. 
     
     
         9 . A method for fabricating an object from a metal and a metal like material on a build table while controlling the temperature of the object further comprises:
 measuring the temperature of the object; and   spraying object with quenchant fluid.   
     
     
         10 . The method of  claim 9  wherein the spray of quenchant fluid is robotically positioned in multiple axes independent of the robotic motion of the deposition head. 
     
     
         11 . The method of  claim 9  wherein the quenchant fluid is a gas. 
     
     
         12 . The method of  claim 9  wherein the temperature of the quenchant fluid is maintained. 
     
     
         13 . A method for fabricating an object from a metal and a metal like material on a build table while controlling the temperature of the object further comprises:
 applying quenchant at a temperature that cools the object in response to the object temperature.   
     
     
         14 . The method of  claim 13  further comprising quenching parameters that allow manipulation of material properties of the object. 
     
     
         15 . The method as set forth in  claim 14  further comprising variations in temperature hold times to obtain proper heat treat profile. 
     
     
         16 . The method as set forth in  claim 14  further comprising variations in temperature hold times to obtain desired material hardness and ductility. 
     
     
         17 . The method as set forth in  claim 14  further comprising the step of controlling temperature variations in temperature hold times to reduce stresses in the object. 
     
     
         18 . The method as set forth in  claim 13  further comprising the step of increasing deposition rates in response to said cooling. 
     
     
         19 . The method of  claim 13  further compromising the step of controlling object temperature so that small part geometries are deposited without geometry errors or deformation.