| 摘要 |
PURPOSE:To maintain the section shape at the time of secondary forming such as bending and to improve the impact energy absorption performance at the time of collision when an extrude-forming piece made of aluminum alloy used as an automobile member is extruded. CONSTITUTION:By controlling the temperature of a part of a molding die 21 of an extrusion machine 20 by the heating action of a heating member 28 and the cooling action of a cooling member 29, at the time of extrusion of aluminum alloy, a low strength part 22a where a crystalline structure is coarsened and which is small in tensile strength, low in the yield point and large in elongation and a high strength part 22b where a crystalline structure is fined and which is large in tensile strength, high in the yield point and small in elongation are formed on the extrude-forming piece 22. By executing secondary forming such as bending on the low strength part 22a, the section shape of the extrude- forming piece 22 can be maintained. Further, at the time of collision, the low strength part 22a is crushed easily and the absorption performance of impact energy becomes high. |
