| 摘要 |
PROBLEM TO BE SOLVED: To reduce manufacturing cost and weight of a sheet metal by forming a tubular boss part, which has a desired bore, thickness and height as well as a satisfactory strength, integrally with the sheet metal by using a small press. SOLUTION: A plurality of notches 4a are radially formed on the outer circumference of a planar metallic base material 4, with drawing performed on this notched material 4 to form a bulged part 5a. Then, a post processing is applied to this bulged part 5a to form the boss part 3a.
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