热处理状态和工艺顺序对铝型材弯曲回弹的影响

采用实验和数值仿真相结合的方法研究了材料热处理状态和工艺顺序对6063铝型材弯曲回弹的影响规律和机理.结果表明:型材绕弯变形区内外层材料分别为压应力和拉应力起主导作用,中性层附近材料为明显的拉-压两向应力集中区.外力卸载后,中性层存在很大的残余拉应力;挤压态型材经人工时效处理后绕弯成形回弹角将会变大.且随着人工时效时间的延长,内外侧材料最大拉压应力差变大,回弹角逐渐增大;弯曲型材后续经人工时效或电泳烤漆处理,产生二次回弹.且弯曲角度越大,热处理后回弹角会增大.进一步延长人工时效时间,弯曲型材的回弹角基本不变;弯曲型材的三种成形工艺顺序方案中,挤压态型材先经冷弯成形再紧接着进行人工时效和电泳烤漆处理总的回弹角最小.

Influence of Heat-treated Condition and Process Sequences on the Springback of Aluminum Bent Profiles

Methods in numerical simulation combined with experiments were used to study the influence of heat-treated condition and process sequences on the springback of 6063 aluminum bent profiles. The results show that the inner and outer materials of profile cross-section during bending process suffer compressive and tensile stress, while the nearby neutral fiber suffers an obvious tensile-compressive stress concentration. The neutral fiber of the whole plastic deformation region has a larger residual tensile stress after unloading. The springback angle of extruded profile increases after artificial aging. With the increase of artificial aging time, the difference of maximum tensile and compressive stress between the inner and outer materials increases, and consequently, the springback angle gradually increases. The curved profile also rebounds after artificial aging and electrophoresis paint, and with the increase of the bending angle, the springback angle increases. The artificial aging time further increases, but the rebound angle of curved profile remains unchanged. The total springback angle is minimum when the extruded profile is first processed by cold bending, and then by artificial aging and electrophoresis painting.