Patent ID: 7423233

Claim:
A butt welding apparatus for butt welding end faces of at least one plate member by electric resistance heating, comprising: means for supporting the at least one plate member such that the end faces abut each other and form a butt portion; a pair of electrode members disposed opposite to one another for performing electric resistance heat welding of the butt portion, said pair of electrode members comprising a first electrode member provided at a first side of the butt portion and a second electrode member provided at a second side of the butt portion opposite to the first side, said first electrode member being positioned so that it extends across the butt portion and having an outer surface with a first convex portion which faces the at least one plate member and gradually retreats therefrom as it extends from an intermediate portion of the first electrode member outer surface and the second electrode member being positioned such that it extends across the butt portion; and means for causing relative movement of the first and second electrode members toward each other and contacting of a surface of the at least one plate member with the first electrode member at the first side of the butt portion and surfaces of the at least one plate member on opposite sides of the butt portion, at the second side thereof, with the second electrode member and cause an end face thereof to deform toward the other end face, melt and join with the other end face.