| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a drum with a boss capable of easily keeping uniform quality of the drum with a boss. SOLUTION: This manufacturing method comprises a process to draw a flat plate 30 with a previously prepared hole on the center to form a cylindrical body with bottom, a process to reversely draw the center part of this cylindrical body with bottom to form a small diametral cylindrical part 35 toward the opening side, and a process to increase the thickness of this small diametral cylindrical part to form a boss. Thereby, a durm with a boss is formed integrally out of the flat plate 30, so that the center line of the boss is easily kept coaxial to the drum and there is no fear of generation of strain on the boss and drum owing to welding heat. |
