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 for fabricating a three dimensional object comprising:
 a multi-axis robotic system configured to support and move a deposition head;   the robotic system contained within a sealed enclosed space;   an oxygen sensor within the enclosed space.   
     
     
         2 . The additive manufacturing apparatus as set forth in  claim 1  for fabricating a three dimensional object further comprising means for introducing a gas and monitoring the oxygen concentration within the enclosed space. 
     
     
         3 . The additive manufacturing apparatus as set forth in  claim 2  further comprising a means for reducing or discontinuing gas flow in response to said oxygen monitoring. 
     
     
         4 . The additive manufacturing apparatus as set forth in  claim 1  further comprising an air filtration system. 
     
     
         5 . 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, said tank having a quenching fluid therein;   wherein material is deposited at a set distance from the level of the quenchant.   
     
     
         6 . The additive manufacturing apparatus as set forth in  claim 5  wherein said deposition head is capable of being fully submerged in said quenchant. 
     
     
         7 . The additive manufacturing apparatus of  claim 6  further comprising use of wire with internal inert gas filler. 
     
     
         8 . An additive manufacturing apparatus to fabricate objects by depositing metal or metal like materials in three dimensions comprising:
 a build table;   a plurality of deposition heads configured to deposit the metal objects on the build table, wherein each of the deposition heads includes a tool bracket;   a multi-axis robotic system configured to support the deposition head;   wherein said build table is configured to be adjustably located in a tank, said tank having a quenching fluid therein;   wherein the plurality of nozzle assemblies are configured to deposit different wire sizes of metal or metal-like material.   
     
     
         9 . The method of  claim 8  further comprising each of the plurality of deposition heads configured to deposit a different material. 
     
     
         10 . The method of  claim 8  further comprising one welding power supply and changing computer control programs for each deposition head. 
     
     
         11 . The method of  claim 10  further comprising using switchable power buss to provide power to each of said multiple deposition heads. 
     
     
         12 . An additive manufacturing method for fabricating a three dimensional object formed from a metal or metal-like material, wherein the geometry and temperature of the object is continually monitored and deviations from the desired geometry or temperature are corrected prior to continuing. 
     
     
         13 . The additive manufacturing method of  claim 12  further comprising using the arc current to continually monitor the height of the object. 
     
     
         14 . The additive manufacturing method as set forth in  claim 12  further comprising using a computer control program capable of depositing one or more layers using one power setting alternated with one or more layers deposited using a second power setting. 
     
     
         15 . The additive manufacturing method of  claim 12  further comprising using a computer control program to correct defects by moving the deposition head back over low sections prior to proceeding with the next layer. 
     
     
         16 . The additive manufacturing method as set forth in  claim 15  further comprising using a computer control program to correct surface defects by changing the robotic travel speed, and by changing the deposition parameters of the next layer when reaching the location of the detected defect. 
     
     
         17 . The additive manufacturing method of  claim 16  further comprising the step of using a computer control to abort the build process prior to completion of the object. 
     
     
         18 . The additive manufacturing method of as set forth in  claim 17  further comprising using a memory storage device and recording all locations of any detected defects for later analysis. 
     
     
         19 . The method of  claim 18  further comprising creating a visual display of the locations of any detected defects.