【作者】 蔡霞；

【导师】 阮锋； 阮毅；

【作者基本信息】 华南理工大学 ， 机械工程， 2010， 硕士

【摘要】 板料弯曲成形是一种塑性加工方法,被广泛应用于各个领域。在板料成形过程中,回弹是不可避免的现象,它的存在直接影响着冲压件的成形精度。回弹问题是一个十分复杂的问题,其影响因素很多且相互耦合,表现出高度的非线性。加上实际生产条件的复杂多变性,使问题变得更加难以把握。因此,回弹一直是影响、制约模具设计制造和产品质量的重要因素。回弹是板料成形后,当外力去除时,工件内残余应力使其产生的弹性恢复变形。完整的回弹是整个成形历史的累积效应,包括加载过程和卸载过程。由于弯曲后的回弹程度与众多因素有关,这使得回弹过程非常复杂且难以精确控制。回弹问题的存在对零件的尺寸精度和形位公差精度造成极大的影响,因此对回弹规律进行深入研究有着重要意义。本文主要是针对多角弯曲件弯曲回弹问题,通过理论分析法分析了板料弯曲成形及回弹的应力分布,利用数值模拟结合实验的方法,总结出影响板料回弹的主要因素,并研究了各个因素对多角弯曲件弯曲回弹影响规律。主要研究工作如下:首先,本文就弯曲回弹的原理进行阐述;分析冲压成形及回弹产生的过程和特点;并根据理论知识分析了单角弯曲件弯曲及回弹变形区的应力分布及非弯曲区的变形情况,进而研究讨论了多角弯曲件的弯曲回弹过程。讨论了多角弯曲件回弹的表示形式和影响回弹量的因素。第二,利用有限元数值模拟软件ABAQUS,采用混合模拟算法模拟多角弯曲件的冲压成形和回弹过程。就有限元模拟的关键技术进行研究讨论,最终选择了适合本论文的技术参数,为后续研究多角弯曲模拟研究做好准备。第三,根据实验需要,设计并制造一整套实验模具。通过正交实验方法,对多角弯曲件就选定的四个因素进行冲压实验,并对测量得到的回弹角度进行极差分析,得出了影响因素的主次顺序和最佳工艺参数组合。最后,对多角弯曲件的回弹进行模拟研究,对弯曲件回弹的影响因素进行分析,特别是各个弯曲角之间的相互影响。通过对多角弯曲回弹影响因素进行模拟分析,总结出各个因素对回弹影响的规律,这对于把握弯曲过程中存在的回弹有很重要的指导意义。更多还原

【Abstract】 The metal sheet bending is a kind of plastic processing methods, which is widely used in various fields. In the metal sheet forming process, the springback is an inevitable phenomenon, and it directly affects the precision of workpiece. Springback is a very complex issue, which concludes many factors coupled and shows a high degree of nonlinearity. At the same time, the problem becomes more difficult to grasp because of the complex conditions in the actual production. So, the springback has been an important factor, which restricted the mold design, manufacturing and product quality. Springbanck is that the residual stress makes the workpiece produce the elastic recovery, after the metal sheet forming, and then, the external force to remove the workpiece. The complete springback is a historical cumulative effect of the whole forming, including loading and unloading process. The rebound process is very complex and difficult to accurately control, because the degree of the springback is affected on many factors. It is great significance to study the problem of springback, as the existence of the resilience has been severely affected the part of dimensional accuracy , precision of form and position tolerances.The dissertation is to summarize the main factors influencing rebound and study the rules of the various factors on multi-angular bending and springing according to the problem of multi-angular bending and springing, through theoretical analysis on the stress distribution of the sheet metal bending and springback, using the method of numerical simulation computer simulation and combining experiments. The main research work is as follows:Firstly, the dissertation elaborates on the principle of the metal sheet bending and springback, analyses the process and characteristics on the metal sheet forming and springback and researches respectively the stress distribution and deformation in the deformation zone and non-deformation zone during Bending and Springback about the single angle part based on the theoretical knowledge, and then discussed the process of the multi-angular part bending and springback. The dissertation also explained the forms to express the springback angle and the factors to influence springback.Secondly, the dissertation simulates the process of the multi-angular part bending and springing, using hybrid simulation algorithm based on ABAQUS. The dissertation also studied the key technologies about numerical simulation and ultimately selected the suitable technical parameters, which is to prepare for further research.Thirdly, the dissertation designs and manufactures a set of molds according to the experimental needs. Through the method of orthogonal experiment, the paper obtains the primary and secondary order of the factors and gets the best parameters, with the four factors selected experimented, the springback angles measured and the datas studied with the method of a range analysis.Finally, the dissertation studies the simulation of the multi-angle piece and analyzes the factors which affects the springback and especially researches the various interactions between the bend angles. The dissertation also concludes the rules of the factors through studying the factors, which is significant to master the springback in the process of bending and springing.更多还原