| 摘要 |
When forming a dowel section by performing press working on each of portions constituting side walls of a buckle base member, a die of a negative clearance with a punch portion (2) is used whose length or diameter is larger than a length or diameter of a die portion (3), the dowel section being required as a guide for a tongue inserted into a buckle and as a load receiver when a latch member is elongated at a time of collision etc. When a ratio C/t of a clearance C between the punch portion and the die portion with respect to a plate thickness t of the buckle base member is set within a range of -(30 to 5)%, no crack is generated in the root of the dowel section, and the dowel section of a shear cross-section length >=0.25xt, a shear cross-section starting height >=0.7xt, and a height of (0.70 to 0.95)xt is easily obtained, and the perpenducularity of the dowel section side surface is enhanced. |
