To provide a method capable of reducing thickening in the skelp width direction due to droop of a skelp edge part/edge forming and reducing an outer face streak and an inner face bead of a forge weld abutting part by an I shaped butting of edges.
In a production process, in which a skelp 1 reheated to 1300-1350°C in a heating furnace 2 is formed by a vertical stand forming roll 3/a horizontal stand forming roll 4 and is made into a tube by forge welding with a forge welding roll 6, by arranging an auxiliary heating device 8 immediately before forming and raising a temp. of the skelp edge part, an edge is formed with pressing an edge of the skelp 1 on a seam guide roll of a horizontal stand forming roll pass. By this method, thickening in the skelp width direction due to droop of a skelp edge part and edge forming, is reduced, an outer face streak and an inner face bead of a forge weld abutting part is reduced by I shaped butting of edges. Further, quality of the forge weld abutting part is significantly improved.
SUMIMOTO DAIGO
TERADA YOSHIO
