矩形截面型材拉弯成形

针对铝合金矩形中空截面挤压型材进行了不同预拉和补拉的拉弯成形试验研究,获取了预拉和补拉对成形精度的影响规律.截面畸变是影响成形精度最主要的因素,由弯曲过程中的径向压力引起.试验表明,型材靠模弯曲即发生截面畸变,主要表现为上腹板的塌陷,沿型材长度方向截面畸变量不同,最大畸变量并不位于型材中间对称截面处;增大预拉和补拉,截面畸变增大.弯曲卸载回弹是影响零件贴模度的主要因素,其大小受多种因素影响,规律复杂.增大预拉和补拉,回弹减小;当预拉和补拉增大到一定值时,增大拉伸量减小回弹的效果不再明显.

Stretch bending of aluminum extrusion

An experimental study on stretch bending of aluminum extrusion was conducted under different pre- and post-stretching elongation. Cross section distortion caused by radial stress during bending process is one of main parameters concerning forming precision. As shown in the test, cross section distorted as the extrusion was bent into contact with the die. Main distortion of cross section is sagging of upper flange. Sagging distribution along the extrusion was given and sagging of middle cross section is not the maximum. It can be seen that the larger is pre- or post-stretching elongation, the larger is cross section distortion. Springback is a common phenomenon during the unloading process, which is influenced by many parameters and difficulty to be eliminated. Pre-and post-stretching elongation can both reduce springback. When pre-stretching elongation exceeds a certain value, its effect on reducing springback is not obvious, which is similar with post-stretching elongation.