TWI

The development of robots, tools and control systems for three-dimensional friction stir welding of aluminium alloy plate up to 10 mm thickness is described. Robots have been developed with a triangulated arm construction, which provides the necessary rigidity for friction stir welding. Load control is implemented by fitting a load cell between the tool and the robot head. Force is measured at a frequency of 60 Hz, and is computer-controlled. Tool developments include pin shape optimisation to minimise weld instability, and shoulder shape to allow the tool axis to remain normal to the weld surface for all weld geometries. Welding units which do not require separate backing to contain the welding forces have also been developed.

2nd International Symposium, 26-28 Jun 2000, Session 6, Paper 02