Method and apparatus for manufacturing metallic pipe

In an apparatus for manufacturing a metal pipe from a generally flat skelp and having a forming mill with a train of U-shape forming stands, a prefinishing stand and a train of finishing stands, the improvement comprising, in the forming stands, a plurality of pairs of spaced opposed forming rolls along the length of the forming mill with the rolls of each pair symmetrically rotatably mounted on opposite sides of the centerline of the path of the skelp through the forming mill and having profiles with a generally V-shaped recess therein defined by portions of the roll profile having straight lines for holding said skelp with at most the edge surfaces thereof in line contact with the roll profile in the bottoms of said recesses and the outer surface of the skelp adjacent the edges in substantially only point contact with the profiles of each of the pairs of forming rolls in the bottoms of said recesses so as to apply a bending load to the skelp, means in each stand for mounting said rolls for movement toward and away from each other and for movement transversely to the direction of movement of the rollers toward and away from each other and in the direction of bending of the skelp, the positions of the V-shaped recesses in the rolls of successive pairs of rolls in the direction toward the output end of the forming mill being further around the periphery of the forming stands from the position of the recess in the first forming stand.

In an apparatus for manufacturing a metal pipe from a generally flat skelp and having a forming mill with a train of U-shape forming stands, a prefinishing stand and a train of finishing stands, the improvement comprising, in the forming stands, a plurality of pairs of spaced opposed forming rolls along the length of the forming mill with the rolls of each pair symmetrically rotatably mounted on opposite sides of the centerline of the path of the skelp through the forming mill and having a truncated conical roll surface oriented in one direction from a line transverse to the length of the forming mill, a further pair of spaced opposed forming rolls along the length of the forming mill succeeding the last pair of said plurality of pairs of rolls, the rolls of said further pair of rolls being symmetrically rotatably mounted on opposite sides of the centerline of the path of the skelp and having a truncated conical roll surface oriented in the opposite direction to the rolls of said plurality of pairs of rolls, a further roll adjacent the smaller ends of said rolls of said further pair of rolls and rotatable around an axis transverse to the said smaller ends of said further pair of rolls and positioned between said further pair of rolls, and a further plurality of pairs of rolls, one pair being positioned between each adjacent pair of said firstmentioned pairs of rolls, one pair between the last pair of said firstmentioned pairs of rolls and said further pair of rolls and one pair on the opposite side of said further pair of rolls in the direction of the length of said forming mill, the rolls of said further plurality of pairs of rolls being coaxially rotatably mounted around an axis transverse to the rolls of the firstmentioned pairs of rolls and spaced from each other and having V-shaped recesses therein, said rolls of said further plurality of pairs of rolls being on the opposite side of the path of the skelp through said forming mill from the rolls of said firstmentioned pairs of rolls and the V-shaped recesses opening toward the positions of the edges of the skelp moving along the path of the skelp through said forming mill.