Improvements in Friction Stir Welding Control System and an Extremum Controller for Tracking Friction Stir Extrusion Process

Abstract

Friction Stir Welding (FSW) is a solid state joining process that uses a reusable rotating tool to plasticize, mix, and join materials. For this thesis the control system of the lab’s FSW machine was redesigned to improve its safety, capabilities, and usability for future research. This new system allows for measurement of traverse and lateral welding forces and the ability to monitor backlash in the machine. An extremum controller for tracking a Friction Stir Extrusion (FSE) process was also developed using this system. FSE is a method joining dissimilar materials and works by extruding aluminum into a premade groove cut in a steel piece, thus forming a mechanical interlock. The controller was then successfully demonstrated to automatically correct for misalignment of the tool and groove for the FSE process by maximizing the amount of extruded material.