Precise positioning for a welding electrode which follows a three dimensional weld path

A welding apparatus for producing a weld along a weld path within a workpiece, said apparatus comprising:

• a welding electrode mounted on a welding electrode bracket;
• means for producing relative movement between said welding electrode and said workpiece, said relative movement comprising a plurality of separate axes forming an x-axis and a y-axis and a z-axis, said axes being perpendicular to each other, said z-axis being in a direction toward and away from said workpiece;
• a filler wire assembly fixed relative to said welding electrode, said filler wire assembly having an outer free end located directly adjacent to said welding electrode;
• a housing, said welding electrode bracket being rotatably mounted upon said housing about a first axis, said welding electrode being located on said first axis, the rotation of said welding electrode bracket being controlled by a predetermined program, said welding electrode bracket to rotate to continuously maintain said outer free end of said filler wire assembly at a precise position relative to said welding electrode, with said precise position being just forward of said welding electrode as such moves along said weld path, said first axis coinciding with said z-axis;
• and
• said welding electrode being movable along a lineal path relative to said welding electrode bracket, said lineal path coinciding with said z-axis, said movement along said lineal path being controlled by a control means, said control means maintaining the arc voltage constant by physically controlling the spacing of said welding electrode from said workpiece.