METHOD OF MANUFACTURING SHEET METAL BACK FACE PULLEY

摘要

A method of manufacturing a sheet metal back face pulley, comprising a step for preparing a sheet metal cup-like material (4) having a circular base plate part (2) and a tube part (3) extending from the outer peripheral edge part of the base plate part (2) in one axial direction of the base plate part (2), a step for forming, on the tube part (3), an annular projected part (15) projecting in a direction opposite to the direction in which the tube part (3) is extended by forming an annular groove part (13) at the upper end part of the tube part (3), and a step for forming the outer peripheral surface (15a) of the projected part (15) flush with the outer peripheral surface (30) of the tube part (3) by pressingly holding the annular projected part (15) and the tube part (3) by a rotating drag (5e), a rotating cope (6d), and a roller (18) for forming flat surface until at least the annular groove part (13) is eliminated. Since the axial length (h4) of the sheet metal back face pulley (11) is increased, the overall length of the increased axial length (h4) can be utilized as an effective length.