METHOD OF FORMING MATERIAL MADE OF SHEET METAL INTO BOSS PART AND METHOD OF FORMING SHEET METAL INTO PULLEY

A method of forming a boss part sufficient in thickness and assured of a height of projection even when reduced in diameter, without excessively reducing the thickness of the metallic material and with the use of a small press, in which, through such processes as convexly bending a metallic material (1) in the form of a flat sheet, boring a hole (5A) in the top of said bent material, and bending that portion of said bent part between the peripheral part of said hole and the peripheral edge (1e) of the sheet in the direction reverse to that in the previous bending process while controlling radial outward stretch of the peripheral edge (1e) of the material (1), a cylindrical boss part (6) to project toward one side thereof is formed at the central part of the material (1).