Patent ID: 8899467

Claim:
A thermal stir welding system, comprising: a thermal stir welding head assembly to include a first plate defining a first surface, a second plate spaced apart from said first plate and defining a second surface that opposes said first surface wherein said first surface is maintained parallel to said second surface, and a rod passing perpendicularly through said first surface and said second surface wherein said rod is rotatable about a longitudinal axis thereof relative to said first surface and said second surface, said welding head assembly adapted to have a work piece disposed between said first surface and said second surface with the work piece in a plastic state thereof at least in a vicinity of said rod when rotating about said longitudinal axis thereof as said welding head assembly and the work piece experience relative movement therebetween in a direction perpendicular to said longitudinal axis and as the work piece is subjected to a compressive force applied by said first plate and said second plate; a first source coupled to an edge of said first plate, said edge of said first plate adjoining said first surface, said first source applying a first ultrasonic wave to said edge of said first plate wherein said first ultrasonic wave propagates through said first plate and parallel to the work piece adjacent to said first surface and said direction of relative movement; and a second source coupled to an edge of said second plate, said edge of said second plate adjoining said second surface, said second source applying a second ultrasonic wave to said edge of said second plate wherein said second ultrasonic wave propagates through said second plate and parallel to the work piece adjacent to said second surface and said direction of relative movement, wherein friction between said welding head assembly and the work piece is reduced as said first ultrasonic wave propagates through said first plate and said second ultrasonic wave propagates through said second plate.