METHOD OF MANUFACTURING SHEET METAL PRODUCT HAVING CYLINDRICAL PORTION AT INNER CIRCUMFERENTIAL SIDE THEREOF

摘要

A method of manufacturing a sheet metal product having a cylindrical portion at the inner circumferential side thereof, capable of forming a cylindrical portion (84) at the inner circumferential side of a sheet metal work (W) without using welding and burring processes, making unnecessary a welding operation which is troublesome, and which deteriorates the working environment, and reducing the restrictions on the increasing of the axial length of the cylindrical portion (84). The gist of the method resides in that a process for rolling a cylindrical portion (84) on an opened edge section (82) of a sheet metal work (W), which has an opening (81), by pressing a surface (26) of an inner mold (25) provided in the opening (81) against the opened edge section (82) with the inner mold (25) moved in the diametrically outward direction of the work (W) as the sheet metal work (W) is turned around the axis of the opening (81) with the work (W) set in a predetermined position is carried out. According to this method, a cylindrical portion (84 ) can be formed at theinner circumferential side of the sheet metal work (W) without using welding and burring processes.