Friction stir welding tool for welding variable thickness workpieces

Abstract

A friction stir welding tool for welding workpieces of variable thickness. The tool is characterized in that the displacement between a shoulder that presses down on an upper surface of the weld, and a tip of a rotating pin that penetrates and softens the workpiece to form the weld, is variable. In one embodiment, when the tool is used in conjunction with an apparatus that allows the shoulder of the tool to ride on and track the workpiece surface, the shoulder is stationary relative to the tool body, and the pin reciprocates relative to the shoulder to maintain contact with the backing plate, thereby providing a weld throughout the workpiece. In another embodiment, when the tool is used on an apparatus that holds the tool in fixed relationship to a backing plate on which the workpiece is held, the shoulder is able to reciprocate relative to the tool, following the upper surface contours of the workpiece, while the pin is able to penetrate through to the rear side of the workpiece to produce a uniform weld.

Dependencies are inferred from the claim text.