激光辅助定模动辊辊弯成型有限元分析

发布时间：2018-03-19 22:41

  本文选题：定模动辊　切入点：激光辅助加热　出处：《北方工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：变截面辊弯成型是一种新兴的材料塑型加工工艺,这种工艺能够解决材料截面复杂多变,板料两侧高度不对称等传统辊弯成型难以实现的加工问题。在一些特殊场合需要用到截面较窄或者截面形状非常复杂的承载零部件,普通的变截面辊弯成型无法完成一次成型,本文提出一种能够一次加工成型的加工工艺,采用该种工艺能成型强度较高,成型半径较小的弯曲件：定模动辊变截面辊弯成型。由于高强钢板强度高、塑性差、材料的延伸率较低,导致加工成型困难,容易在折弯处产生裂纹或材料回弹较大等问题。本文采用激光辅助加热成型的方案来解决上述问题。 本文基于热-应力完全耦合的分析方法,在大型有限元分析软件ABAQUS中,构建了激光辅助的定模动辊辊弯成型装备成型过程。以DP980高强度钢板为研究对象,仿真模拟了成型过程中板料的温度场、应力场的分布,分析了板料塑性应变区域及轧辊成型力的变化,并对比成型角度的关系对成型过程中的材料回弹进行了预测。主要研究工作如下： (1)温度场方面：介绍了热成型研究历程及发展现状,分析了热成型方法,实现了热导率、比热容等热学关键参数的导入,运用传热学及壳体温度场分布设置了板料及上下模具相互耦合的边界条件。通过对比不同温度场仿真过程得出最适宜加工温度。 (2)应力场方面：导入了仿真模拟的力学关键参数,如屈服应力、弹性模量、塑性应变等。分析了等效应力及等效塑性应变,并得到各道次轧辊成型力变化曲线,掌握了成型过程中弹塑性变化的规律。 (3)成型速度及回弹预测方面：分析成型后板料的成形角,预测加工过程中可能产生的回弹,以及比较仿真速度及模拟结果,得到成型效果与加工速度的关系。 通过完全的热力耦合有限元方法仿真模拟了激光辅助的定模动辊辊弯成型生产过程,与试验结果进行比对,发现仿真分析结果正确,对回弹和产生的缺陷进行了预测,并得到了适合加工的温度为600℃,适合加工的速度为50mm/s,适合加工的加热方式为均匀激光加热,加热的最佳位置为板料成型区域。该结果的提出对于激光辅助加热的定模动辊辊弯成型的热力耦合分析过程提供了理论基础,并对该设备的改进以及生产实践具有很重要的意义。
[Abstract]:Variable cross section roll bending forming is a new material plastic processing technology, which can solve the complex and changeable material cross section. In some special cases, the bearing parts with narrow section or very complicated section shape are needed. The common variable cross section roll bending can not complete one forming, and it is difficult to realize the processing problem of the traditional roll bending forming, such as the height asymmetry on both sides of the sheet metal. In this paper, a kind of processing technology that can be processed at one time is put forward. The bending part with higher strength and smaller forming radius can be formed by using this process. Because of the high strength of high strength steel plate, the plasticity is poor because of the variable cross section roll bending forming of fixed die moving roll. The low elongation of the material leads to the difficulty of processing and forming, and it is easy to produce cracks at the bending place or the material rebound is large, etc. In this paper, the laser-assisted heating molding scheme is used to solve the above problems. Based on the thermal-stress coupling analysis method, the laser assisted forming process of moving roll bending equipment is constructed in the large-scale finite element analysis software ABAQUS. The DP980 high strength steel plate is taken as the research object. The distribution of the temperature field and stress field of the sheet metal during the forming process is simulated, and the variation of the plastic strain region of the sheet metal and the forming force of the roll is analyzed. The springback of the material during the molding process is predicted by comparing the relationship of the angle of molding. The main research work is as follows:. 1) in the aspect of temperature field, this paper introduces the research history and development status of thermoforming, analyzes the method of thermoforming, and realizes the introduction of key thermal parameters, such as thermal conductivity, specific heat capacity, etc. By using heat transfer theory and the temperature field distribution of the shell, the boundary conditions of the coupling between the sheet metal and the upper and lower die are set up, and the optimum processing temperature is obtained by comparing the simulation process of different temperature fields. 2) stress field: the key mechanical parameters such as yield stress, elastic modulus and plastic strain are introduced. The equivalent stress and plastic strain are analyzed, and the forming force curves of each pass roll are obtained. The rule of elastoplastic change in forming process is grasped. 3) forming speed and springback prediction: analyzing the forming angle of the formed sheet metal, predicting the springback that may occur in the process of processing, and comparing the simulation speed and the simulation result, the relationship between the forming effect and the processing speed is obtained. The production process of laser assisted rolling roll bending is simulated by a complete thermo-mechanical coupled finite element method. The results are compared with the experimental results. The simulation results are correct, and the springback and defects are predicted. The suitable processing temperature is 600 鈩，

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