基于曲率差的回弹评价方法及其应用  

Springback evaluation method based on curvature difference and its application

作　　者：张赛军[1] 宋世光 王一帆 刘进军 Zhang Saijun;Song Shiguang;Wang Yifan;Liu Jinjun(School of Mechanical and Automotive Engineering,South China University of Technology,Guangzhou 510641,China;Technology Center,Xiangxin Technology Co.,Ltd.,Dongguan 523000,China)

机构地区：[1]华南理工大学机械与汽车工程学院,广东广州510641 [2]祥鑫科技股份有限公司技术中心,广东东莞523000

出　　处：《锻压技术》2022年第4期78-83,149,共7页Forging & Stamping Technology

基　　金：广东省重点领域研发计划项目(2020B010184002)。

摘　　要：针对板料在常温下冲压成形时回弹较大,且现有的评价方法无法判断回弹发生的具体位置而难以准确指导修模的问题,提出一种基于曲率差的回弹评价方法来表征冲压零件回弹,可以准确地显示零件回弹发生的具体位置。首先,采用GOM ATOS Core光学三维扫描仪获取冲压件回弹后的型面,以凸模型面作为冲压件回弹前的型面,再通过MeshLab软件将连续曲面离散为点云。然后,通过多层次B样条插值算法(MBA)将离散的点云拟合成曲面,计算每一点的平均曲率,并以回弹前后的曲率差值来表征回弹大小。最后,将该方法用于某汽车铝合金制成的前风窗下横梁和前防撞梁冲压件的整形阶段,根据冲压件回弹前后的曲率差修正模具型面,并采用位移法对比模具修正前后的零件回弹量。结果表明:前风窗下横梁的正负最大位移分别从+1.415和-2.508 mm减小为+0.707和-1.263 mm;前防撞梁的最大负位移从-3.574 mm减小为-0.801 mm,回弹量明显减小,满足其尺寸偏差要求。说明基于曲率差的回弹评价方法,可以准确地找到回弹发生的部位,并有效地指导回弹补偿工作。The springback of sheet metal is larger during the stamping process at room temperature, the existing evaluation methods cannot determine the specific location of the springback, and it is difficult to accurately guide the die modification. Therefore, in order to solve the above problems, a springback evaluation method based on curvature difference was proposed to characterize the springback of stamping parts, which accurately displayed the specific location of the springback for the part. First, the profile of stamping part after springback was obtained by optical three-dimensional scanner GOM ATOS Core, the punch profile was used as the profile of stamping part before springback, and the continuous surface was discretized into the point cloud by software MeshLab. Then, the discrete point cloud was fitted into a surface by a multi-level B-spline interpolation algorithm(MBA) to calculate the average curvature of each point, and the springback value was characterized by the curvature difference before and after springback. Finally, the method was used in the shaping stage of stamping parts for front windshield lower beam and front anti-collision beam made of aluminum alloy for an automobile, the die profile was corrected according to the curvature difference of stamping part before and after springback, and the springback amount of the part before and after die modification was compared by the displacement method. The results show that the maximum positive and negative displacements of the front windshield lower beam are reduced from +1.415 and-2.408 mm to +0.707 and-1.263 mm, respectively, and the maximum negative displacement of the front anti-collision beam is reduced from-3.574 mm to-0.801 mm, which significantly reduces the springback amount and meets the requirements of its size deviation. Thus, the springback evaluation method based on curvature difference can accurately find the location of the springback and effectively guide the springback compensation work.

关 键 词：板材成形 回弹评价 点云 曲率差 修模 

分 类 号：TG386[金属学及工艺—金属压力加工]