数控渐进成形反弹补偿成形轨迹生成

发布时间：2018-10-19 19:20

【摘要】：数控渐进成形技术作为一种柔性加工技术,因其能快速制造出复杂钣金件而逐渐发展起来。在发展的同时也存在一些问题,如成形精度问题。反弹是制约板材件成形精度的关键问题,解决反弹的传统方法是实验法,根据测量的反弹量进行补偿,但是由于引起反弹的诸多因素的复杂性,一次补偿往往难以达到精度要求,而多次实验则浪费时间与物力,因此本文提出一种基于数字模拟显/隐式有限元分析的反弹量预测与补偿成形轨迹生成方法,并开发一种专门的轨迹生成软件系统。本文将板材件的反弹分为成形过程中的反弹和卸载以后的反弹。首先,由待成形件生成第一个成形轨迹,以该轨迹的刀位点进行显式有限元分析模拟板材成形过程中的反弹,利用显式分析的结果进行隐式有限元分析模拟卸载以后的反弹。其次,从隐式有限元分析的结果中导出板材件模型所有节点的坐标,进而对反弹模拟后的板材件曲面进行重建,将曲面重建模型与理论模型进行比较,计算出法向反弹偏差值。第三,根据法向反弹偏差值将理论模型不等距偏置生成补偿面与成形轨迹,利用该轨迹点再次进行有限元分析,重复以上过程直至满足用户设定的尺寸精度要求为止。第四,针对多次补偿过程中补偿距离的不同提出补偿迭代算法以及多次补偿过程中出现的补偿面不光滑的问题提出平滑处理算法。同时本文开发了基于VC++6.0,MFC类与OPenGL可视化平台的软件系统,能够较系统地实现等高线轨迹生成、曲面重建、反弹偏差计算、补偿面成形轨迹生成等功能。最后,从有限元分析中得出结论:进行三次补偿就可以满足成形精度要求。然后将理论模型的成形轨迹和三次补偿以后的补偿模型的成形轨迹进行成形实验。成形实验结果表明:本文提出的基于数字模拟显/隐式有限元分析的反弹量的预测与补偿成形轨迹生成方法是可行的,能够提高板材件的成形精度。
[Abstract]:As a kind of flexible machining technology, numerical control incremental forming technology has been developed gradually because of its rapid manufacturing of complex sheet metal parts. At the same time, there are some problems, such as forming precision. Rebound is a key problem that restricts the forming accuracy of sheet metal. The traditional method to solve the rebound is experimental method, which is compensated according to the amount of rebound measured. However, because of the complexity of many factors that cause the rebound, The primary compensation is often difficult to achieve the precision requirement, but many experiments waste time and material resources. Therefore, this paper presents a method for predicting the rebound quantity and generating the compensation forming trajectory based on the digital analog explicit / implicit finite element analysis. And develop a special trajectory generation software system. In this paper, the rebound of sheet metal is divided into the rebound in the forming process and the rebound after unloading. First, the first forming track is generated from the part to be formed, and the rebound during sheet metal forming is simulated by explicit finite element analysis with the tool location of the track. The rebound after unloading is simulated by implicit finite element analysis based on the results of explicit analysis. Secondly, the coordinates of all nodes of the plate model are derived from the results of implicit finite element analysis, and then the surface of the plate after the rebound simulation is reconstructed, and the surface reconstruction model is compared with the theoretical model, and the deviation value of the normal rebound is calculated. Thirdly, according to the deviation value of normal rebound, the compensation surface and the forming trajectory are generated by the theoretical model with non-equidistant bias, and the finite element analysis is carried out again by using the trajectory point, and the above process is repeated until the precision requirement of the user is met. Fourthly, a compensation iterative algorithm is proposed for different compensation distances in the process of multiple compensation, and a smoothing algorithm is proposed for the problem of non-smooth compensation surface in the process of multiple compensation. At the same time, a software system based on VC 6.0 / MFC and OPenGL visualization platform is developed, which can realize the functions of contour track generation, surface reconstruction, rebound deviation calculation, compensation surface forming trajectory generation and so on. Finally, the conclusion is drawn from the finite element analysis that the accuracy of forming can be satisfied with the third compensation. Then the forming trajectory of the theoretical model and the compensation model after the cubic compensation are tested. The experimental results show that the proposed method is feasible to predict and compensate the forming trajectory based on the digital analog explicit / implicit finite element analysis, and can improve the forming accuracy of sheet metal parts.
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

【相似文献】