| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent breakage of a joined part by regulating the butt step of plates on the side where the expansion forming force is applied in the prescribed range to prevent a large shearing force from being applied to the joined part during the pressing in forming the differential thickness tailored blank of a parts in which members of different thickness and different strength are joined with each other and whose expansion forming direction is changed. SOLUTION: A differential thickness tailored blank 1 comprises a thinner plate 2, a thicker plate 3, and a joined part 4, and the butt step (d) of the plates is formed in the joined part 4. The expansion forming is performed in the direction of the arrow. When the butt step (d) of the plates is increased, the shearing force to be applied to the joined part 4 during the forming becomes excessive leading to the breakage of the joined part, and based on the results of the forming test, the butt step (d) of the plates on the side where the expansion forming force is applied, is in the condition to satisfy the inequality of F3 .d/F2 .t2 <0.5, where t2 is the thickness of the thinner plate 2, F2 is the tensile strength thereof, t3 is the thickness of the thicker plate 3, and F3 is the tensile strength thereof, and the butt position is changed.</p> |
