【作者】 栗振斌；

【导师】 付增祥； 杨合；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2004， 硕士

【摘要】 薄壁弯管件以其优良的力学性能、多样的功用性和较高的性价比在航空航天等领域获得了广泛的应用。回弹是管材弯曲卸载后必然发生的现象，回弹现象的存在严重影响了弯管生产的精度和效率，从而也就成为重点研究对象之一。因此，本文采用有限元数值模拟对不锈钢和铝合金两种材料薄壁管件的弯曲回弹规律进行了详细的研究，主要的研究内容及成果如下： (1) 研究了薄壁管件的弯曲成形机理，对该成形过程建立了符合实际的弹塑性有限元模拟模型。对管弯曲回弹有限元模型中的关键技术进行了研究，模拟中采用三维管弯曲几何模型，并采用八节点实体单元实现计算模型的离散化。对于弯曲过程中的接触问题采用了面一面接触模式，并采用库仑摩擦模型处理接触面间的摩擦问题。有限元模型的建立及关键技术的处理为弯管回弹规律的研究奠定了基础。 (2) 基于管弯曲回弹有限元模拟模型研究了弯曲工艺参数和材料参数对管弯曲回弹的影响规律。结果表明，弯管回弹角随弯管角度、相对弯曲半径及芯棒与管壁间隙的增大而增大；随材料硬化指数的增大而减小；随材料硬化系数的增大而增大。 (3) 基于已获得的弯管曲回弹规律，采用VB(Visual Basic)语言、SQL(Structure Query Language)语言及微软Access数据库软件设计并开发了通过数控过弯实现弯管回弹补偿的系统。从而为管材弯曲回弹角的补偿提供了一条可行的途径。更多还原

【Abstract】 The thin-wall tubes are widely used in lots of fields because of their excellent properties, various functions and hige feature-price ratio, such as in aviation and astronavigation fields etc. The springback which happens consequentially after unloading is a flaw which acutely reduced the efficient production of the tubes, and at present, much research work have been done about finding the appropriate solution to the springback. This paper conducted the detailed research to obtain the rules existing in the bending springback phenomenon of the stainless steel tube and the Al-alloy tube, based on the elasto-plasticity FEM. The main research content and achievements are as follows:(1) Based on the research of the forming mechanism of tube bending, the elastic-plastic FEM simulation model which is very important to the research of the springback rules of bending tube has been established, the essential technical questions to carry out the simulation was treated as well. The deforming body was dispersed by eight-node solid element, and surface-to-surface contact element was used for creating the contact pair, besides, the Coulomb friction model was used to solve the friction questions between contact faces.(2) Based on the tube bending FEM simulation model, the tube bending springback rule under the different craft parameters and the material parameters was studied. The results indicated that the springback quantity of bent tube grows with the increasing of the elbow piece angle, the relative bending radius and the gap between the core craft and the tube wall, falls down with the increment of material hardening index value, and increases with the increment of the material hardening coefficient value.(3) Based on the obtained bent-tube’s springback rules , the VB language, the SQL language and Microsoft Access database software, an over-bending compensate system of the NC tube bending springback was designed and developed. This system can provide a feasible method to compensate the springback angle of tube bending process.更多还原