轨道车辆铝型材结构件拉弯成形技术的研究

发布时间：2018-11-04 21:35

【摘要】：铁路是交通运输体系的重要组成部分，高速铁路作为铁路体系的一大分支近年来正在飞速发展。列车运行速度不断提高，随之而来的列车营运舒适性、安全可靠性、经济适用性问题就愈加突出，与这些息息相关的车体轻量化就显得尤为重要。且基于美学、动力学的多重考量[1]，对轨道客车结构件形状、质量等要求越来越高，这就对结构件拉弯成形工艺提出了更高要求。有限元数值模拟比传统经验试制法更省时省力、节约成本，而位移控制模式相对于力控制变形模式有更好的成形精准度，因而，通过对轨道客车铝型材结构件拉弯成形的研究，进一步研究位移控制模式的三维拉弯对实际生产具有重要意义，也有助于加快三维拉弯设备的国产化进程。本文主要对结构件坯料及成形模具进行三维几何建模，再将几何模型导入有限元软件中进行模拟计算及分析。本文以动车组列车车窗梁为研究对象，首先对轨道客车结构件用6065铝合金型材做材料性能试验，得到材料实际力学性能参数。基于切线接触条件理论提出了三维拉弯夹头加载轨迹计算公式，，并根据相应公式计算得到结构件成形加载轨迹。分析讨论了数值模型建立的基本步骤，根据零件加工成形实际情况建立模型，对其进行成形及回弹模拟。具体的研究内容有： 1.对6065铝合金做材料性能试验，得到其屈服强度、抗拉强度、弹性模量、泊松比等力学参数。 2.基于切线接触条件理论提出三维拉弯夹头加载轨迹计算公式，并根据公式利用数学软件计算特定参数值，将求解得到的参数值代入公式中计算得到轨道客车结构件的成形加载轨迹。 3.对比分析了有限元模型建立的基本步骤，包括算法与单元的选择，接触条件的确定，网格划分等，并将计算得到的夹钳加载轨迹作为位移边界条件建立数值模型，进行成形、回弹模拟计算。以最小回弹量为目标进行优化，确定最佳参数，得到理想成形效果。通过对不同总拉伸应变量、预拉量、补拉量下型材零件的回弹量、截面畸变和断裂的讨论，得到如下结论：总拉伸变形量对型材成形质量及回弹影响较大，在材料强度范围内，因零件形状一定，不同的总拉伸变形量所对应的坯料长度不同，最大回弹量随总拉伸应变量增大而增大，但回弹时型材内部应力呈下降趋势；预拉伸量及补拉伸量有利于型材成形，但对回弹量的影响不大，应变量增大有利于卸载后的回弹稳定性。
[Abstract]:Railway is an important part of transportation system. As a branch of railway system, high-speed railway is developing rapidly in recent years. With the increasing of train running speed, the problems of train operation comfort, safety and reliability and economic applicability become more and more prominent, which are closely related to the lightweight of the car body. Based on the multiple considerations of aesthetics and dynamics, the requirements for the shape and quality of the structural parts of the railway passenger cars are becoming higher and higher, which puts forward higher requirements for the forming process of the structural parts. The finite element numerical simulation is more time-saving and cost saving than the traditional empirical trial-production method, and the displacement control mode has better precision of forming than the force control deformation mode. It is important for practical production to further study the three-dimensional bending of displacement control mode, and it is also helpful to accelerate the process of localization of three-dimensional bending equipment. In this paper, the 3D geometric modeling of the blank and forming die of structural parts is carried out, and then the geometric model is introduced into the finite element software for simulation and analysis. In this paper, the window beam of the EMU train is taken as the research object. Firstly, the material properties of 6065 aluminum alloy profile of the rail passenger train structure are tested, and the actual mechanical properties of the material are obtained. Based on the theory of tangent contact condition, a formula for calculating the loading trajectory of a three-dimensional tension and bending chuck is proposed, and the forming loading trajectory of a structural part is obtained by the calculation of the corresponding formula. The basic steps of establishing numerical model are analyzed and discussed. According to the actual conditions of part forming, the forming and springback simulation are carried out. The specific research contents are as follows: 1. The mechanical parameters such as yield strength, tensile strength, elastic modulus and Poisson's ratio of 6065 aluminum alloy were obtained. 2. Based on the tangent contact condition theory, a formula for calculating the loading trajectory of a three-dimensional tension and bending chuck is proposed, and the specific parameter values are calculated by using mathematical software. The calculated parameters are substituted into the formula to calculate the forming loading track of the structural parts of the rail passenger car. 3. The basic steps of establishing the finite element model are compared and analyzed, including the selection of algorithm and element, the determination of contact condition, the mesh division, etc. The calculated clamp loading trajectory is taken as the displacement boundary condition and the numerical model is established for forming. Springback simulation calculation. Taking the minimum springback as the target, the optimum parameters are determined and the ideal forming effect is obtained. Through the discussion of the springback, section distortion and fracture of the profile parts under different total tensile strain, pretension and redrawing, it is concluded that the total tensile deformation has a great influence on the forming quality and springback of the profile, and in the range of material strength, the total tensile deformation has a great influence on the forming quality and springback of the profile. Because the shape of the part is constant, the length of the blank corresponding to different total tensile deformation is different, the maximum springback increases with the increase of the total tensile strain, but the internal stress of the profile decreases with the springback. The pre-drawing amount and the supplementary drawing amount are favorable to the profile forming, but have little effect on the springback amount, and the increase of the strain is beneficial to the springback stability after unloading.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG306

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