Abstract: A welding apparatus (28) for forming a circumferential weld (56) includes a base (30) and a spindle (32) extending perpendicularly from the base. Along the spindle, at its proximal and distal portions, first and second workpiece supporters (38, 40) are provided, respectively, to position workpieces (42) to be welded together therebetween. Between the first and second workpiece supporters, a first arm (44) and a second arm (48) are provided, both extending perpendicularly from the spindle. To a distal end of the first arm, an internal backup roller (46) is rotatably attached, and to a distal end of the second arm, an internal drive roller (50) is rotatably attached. One or more external rollers (52a, 52b), each rotatably attached to an external support (66), are further provided. The internal and external rollers are driven by variable-speed programmable motors (not shown). In operation, the workpieces are mounted onto the apparatus, being sandwiched between the internal rollers and the external rollers.

Abstract: A variable pin length stir friction welding method wherein the stir friction welding pin penetrates the workpiece as the workpiece translates. The stir friction welding pin starting at a zero penetration and extending to the depth needed to repair a weld or to make a weld. Then withdrawing the pin to zero penetration as the work is translated. The weld path is thus ramped into and out of the workpiece leaving no holes which need to be repaired. Circumferential welds can be made by keeping the pin extended to the welding depth for at least one complete revolution of the weld.