Method and apparatus for manufacturing 3d metal parts

A method of manufacturing a metallic part in a weldable material by solid freeform fabrication unrestricted in size and open to the ambient atmosphere, wherein the method comprises:

• generating a computer-generated, three dimensional model of the part, slicing the computer-generated three dimensional model into a set of computer- generated, parallel, sliced layers and then dividing each layer into a set of computer-generated, virtual, one-dimensional pieces and, with reference to layered weld-bead geometry data, forming a computer-generated, direction specific, layered model of the part,
• uploading the direction specific, layered model of the part into a welding control system able to control the position and activation relative to a support substrate, of an electric arc delivered by a high energy tungsten arc welding torch, a plasma transferred arc welding torch, and/ or a gas metal arc welding torch, and a system for feeding a consumable wire placed in an open area build space relevant to the substrate unrestricted in size and open to the ambient atmosphere for generating molten metal,
• directing the welding control system to deposit a sequence of one-dimensional weld beads of the weldable material onto the supporting substrate in a pattern required to form a first layer of the computer-generated, direction specific, layered model of the part,
• depositing a second welded layer by sequencing one- dimensional weld beads of the weldable material onto the previous deposited layer in a configuration the same as the second layer of the computer-generated direction specific layered model of the part, and
• repeating each successive weld bead layer of the computer-generated, direction specific, layered model of the part until the entire part is completed;
• wherein the method further includes:
• displacing the atmosphere within the immediate vicinity of the heat source and the molten metal with an atmosphere of inert gas which produces a required flow rate, and in which that inert atmosphere contains a maximum oxygen concentration, wherein the inert gas is delivered by an apparatus through a matrix of individual gas diffusers and includes a gas manifold compartment that is 80 to 180 mm wide and 180 to 400 mm long or that is of a cylindrical shape up to 400 mm in diameter;
• and
• engaging an induction heating and closed loop cooling apparatus synergic to a welding control system and pre-heating the substrate material including the deposited weld beads, relevant to the type of weldable material, wherein induction heating and cooling cycles are applied constantly or pulsed from the first layer to the final layer, where optimal heating and/ or cooling cycles of the weldable material are relative to the final desired part shape and microstructure.