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

摘要

By allowing the present invention to form a tube (84) inside the circumference of the present invention relates to method of manufacturing a sheet metal article having a tube inside the circumference, welding, regardless of the burring processing (burring) sheet metal work (W), complicated and it does not require welding operations and the work environment deteriorated, and further, an object of the present invention to receive less constrained to hold the axial length of the cylindrical portion (84).; Of the base is opening a naehyeong 25, a workpiece (W) disposed in the sheet metal while rotating at a predetermined position a work piece (W) in the axial periphery of the opening 81, the opening 81 has a 81 move outward in the radial direction by the step of preceding the cylindrical part 84 that by one of naehyeong 25, the mold surface 26, the work piece (W) of the rear mouth pressed against the rim portion 82, the opening edge portion 82 that it performed.; According to the present invention, without using a welding and burring processing it is possible to form the tube 84 inside the periphery of the sheet metal work (W).