Patent ID: 7156275

Claim:
Welding head ( 1 ) for friction stir welding, said welding head ( 1 ) structured and arranged for connection to and driving of a tool ( 2 ) structured and arranged for simultaneous friction stir welding from two opposite surfaces on an object for welding, said welding head ( 1 ) comprising a tool holder ( 9 ), the tool ( 2 ) comprising a primary shoulder ( 6 ), and a probe ( 8 ) arranged to concentrically protrude from both said tool holder ( 9 ) and tool ( 2 ) at said primary shoulder ( 6 ). a single force-generating device ( 3 , 13 ), and a rotary driving device ( 12 ) structured and arranged to impart to the tool ( 2 ) and probe ( 8 ) during operation, cyclic movement around a center axis ( 10 ) of the tool ( 2 ) and relative to the object for welding arranged in conjunction with the welding head ( 1 ), wherein the tool ( 2 ) comprises a secondary shoulder ( 7 ) at an end of said probe ( 8 ) and arranged to face said primary shoulder ( 6 ), and said force-generating device ( 3 , 13 ) is controllable during operationd to act between the primary shoulder ( 6 ) and secondary shoulder ( 7 ) only on said probe ( 8 ) of said tool ( 2 ) concentrically arranged in the tool holder ( 9 ).