Stir Friction Welding Adjustable Friction Head Development

Friction stir welding (FSW) was invented by TWI (The Welding Institute) in Cambridge UK in 1991, it is well known that this economical joining method has excellent welding property and also has advantage in protecting environment. FSW is finding vast applications in the space flight apparatus,aviation production, shipbuilding,high speed train,natural gas packet,automotive industry instead of GMAW process. It will be an important revolution in joining high strength aluminum and its alloy. Although FSW has short history, welding workers has made great progress in FSW, including its principle, materials welded,welding machine and its application.Retractable pin tool(RPT) is a critical technology of researching FSW. But we can discover two shortcomings to FSW. Firstly a keyhool occur in welding line afteer welding,and secondly the pin tool should be relaced with the workpiece which is likely to change thickness of the workpiece during welding. Commonly the measure taked is to add a lead-to shutter and a lead-from shutter.to remove keyhool. But the most challenge is that the keyhool can not be removed to the loop welding line. So RPT is the best way to settle it. To the workpiece with changing thickness, the way formerly taked will take more time to prepare for welding, but it is a technology problem for RPT to settle it.RPT in the text can retreat from the workpiece by the computer controling during the weld ending to remove keyhool. The design allow that the tool length can be changed with the workpiece thickness, and a loop welding line can be formed during the weld ending.