Patent ID: 8087169

Claim:
A method of producing a sheet metal-made back face pulley wherein a sheet metal-made cup-shaped material comprising: a circular base plate portion; and a cylindrical portion which extends from an outer peripheral edge portion of said base plate portion in one direction along an axis of said base plate portion is prepared, an upper end portion of said cylindrical portion is pressed by a groove-forming protrusion disposed in a roll-forming roller, to form an annular groove in said upper end portion of said cylindrical portion, whereby an annular projection that projects in a direction opposite to a direction along which said cylindrical portion extends is formed in said cylindrical portion, and said groove, said projection, and said cylindrical portion are clampingly pressed by a rotary inner mold and a flat-face forming rolling roller to a degree at which said groove at least disappears, whereby an outer circumferential face of said projection, and an outer circumferential face of said cylindrical portion are formed to be flush with each other.