拉弯工艺轨迹分析与修正

Analysis and correction on trajectory of stretch bending process

针对赋予型板一个弯曲力矩的拉弯机的二维型材拉弯,根据拉弯原理,需保证产品件内、外弧的任意点处均处于拉伸状态。为此,针对现有的拉弯机,研究了拉弯旋转中心不同位置对拉弯后产品状态的影响规律。研究结果表明:旋转中心位置与拉弯结束位置的距离需小于5 mm,否则产品件部分点可能处于压缩状态。按照经验设计的拉弯模具产品件不合格,修模后产品件单边拉伸量为11.60 mm,与理论值(12.18 mm)的实际误差为0.48 mm。同时,直线段也存在拉伸量,在设计回弹线时需酌情考虑直线段的拉伸量。通过仿真预测了产品件的成形状态,修模前实际与仿真的凹陷误差为7.5%,修模后为8.3%,因此,在进行拉弯模具设计时可增加仿真对其进行验证,避免后期修模造成资源浪费。

For the 2D profile stretch bending of stretch bending machine that gives a bending moment to the profile,according to the principle of stretch bending,it is necessary to ensure that any point in the inner and outer arcs of product is in a stretched state.Therefore,for the existing stretch bending machine,the influence laws of different positions in the rotation center of stretch bending on the product state after stretch bending were studied.The research results show that the distance between the rotation center position and the final position of stretch bending must be less than 5 mm,otherwise some points of product may be in a compression state.The products produced by the stretch bending die designed according to experience are unqualified.After the die is repaired,the unilateral stretching amount of product is 11.60 mm,and the actual error with the theoretical value(12.18 mm)is 0.48 mm.At the same time,there is also a stretching amount in the straight line segment,so the stretching amount of the straight line segment should be considered as appropriate when designing the springback line.The forming state of product is predicted by simulation,and the actual and simulated dent error is 7.5%before die repairing and 8.3%after die repairing.Thus,the simulation can be added to verify the design of stretch bending die so as to avoid waste of resources caused by later die repairing.