【作者】 肖军；

【导师】 李付国；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2006， 硕士

【摘要】 预成形设计是锻造工艺设计中重要的内容之一,预成形模及预成形形状与终锻件形状直接对应,它直接限制金属的流动状况,从而直接影响成形件的最终形状和成形质量。从理论上说,对于给定的锻件形状,其预成形的形状域是无限的,对预成形的优化设计就是要从这无限的形状域中寻求最优或者接近最优的解。如何设计预锻件形状和预锻模具形状,是生产合格终锻件的关键,也是模具设计的难点之一。而目前国内外在此方面的工作多集中于利用数值模拟技术进行设计结果验证的试错法,其基本思路仍与传统的试错法思路一样,只不过所用的验证手段不同。 针对上述问题,在本课题组已有研究成果的基础上,本文进一步探讨了基于类等势场的材料预成形设计新方法及其正向模拟过程,并将该方法应用到一些具体的成形工艺过程进行了模拟分析。同时,在体积成形预制坯设计中,根据频谱分析原理,提出了一种基于傅立叶变换的预锻模型腔轮廓局部光顺处理新方法,取得了比较满意的结果。 主要成果和新见解如下: (1)从相似理论出发,证明了利用类等势场法模拟材料成形过程的可能性,据此进一步探讨了应用类等势场法来模拟材料成形过程的一般方法及规律,给出了材料变形过程中内部场变量分布的计算方法及其计算结果的可视化处理技术。 (2)运用类等势场模拟法对轴对称件超塑约束胀形工艺进行了初步研究,给出了有模具边界时坯料塑性变形轨迹模型的建立步骤和方法,并与有限元法的计算结果作了对比分析,结果表明,该方法具有计算速度快、计算结果可靠性高、易于实现等特点。与已有静电场法相比,类等势场法不仅能获得合理的预制坯形状,通过分析还可以获得其成形过程的合理场变量分布规律。 (3)将类等势场模拟法运用到盘形件体积成形预制坯设计过程中,同时,根据频谱分析原理,提出了一种基于傅立叶变换的模具型腔轮廓局部光顺处理新方法。通过对45钢盘形件两工步(预锻+终锻)成形过程的模拟,并进一步分析了预锻件、终锻件以及预锻模和终锻模的相关场变量分布情况,综合考虑后,优选出了较理想的预锻模型腔轮廓。对有预锻和无预锻工步的盘形件锻造成形更多还原

【Abstract】 Pre-forging design is one of the most important content in the forging technics design. Because the shape of pre-forging die and pre-forging are directly correspond with the one of finish forging, it limits the flow of metal, so the shape of pre-forging die and pre-forging effect on the final shape and the quality of finish forging. As far as the theory is concerned, for the certain shape of finish forging, the shape region of pre-forging is infinite. It is the duty for the optimum design to find best answer or close to the best from the infinite shape region. It is the key to produce eligible finish forging and one of the difficulties of die design how to design the shape of pre-forging and pre-forging die. At present, national and overseas works about pre-forging design most focus on the method of trial and error which utilizs numerical simulation technology to validate results, the validate method which is adopted is different from the traditional method of trial and error, but its essential idea is the same.Aim for the problem above, the paper further discusses the new design method of the pre-forging on the basis of equipotential field and forward simulation process with the existing research findings gained by our laboratory, and this method has been extended to idiographic forming technicas for simulation analysis. At the same time, a new method to take local smoothness treatment on the die cacity profile is put forward on the basis of Fourier transform according to the principle of spectrum analysis. The studied result is obtained.The main research findings and new outlooks are as follows:1. The possibility that simulating the materials forming process based on the similarity theory has been proved by equipotential field method, and general method and law which simulate materials forming process by equipotential field method is further discussed. The calculation method about the distribution of inner field variables is advanced and the visualization of the results is also put forward.2. The superplastic bulging technics of axisymmetrical circular sheets is researched by equipotential field method, the establishing process and method of theblank plas’ic deformation trajectory model is advanced when the die boundaries exist. Compared with the results of FEM. it shows that this method has the character of rapid calculation, reliable results and easy realization. The reasonable shape of preform and distribution law of field variables in forming process could be obtained by equipotential field method compared to the existent electrostatic field method.3. The equipotential field method is applied in the preform design of gear blank forming process, at the same time, a new method to take local smoothness treatment on the die cacity profile is put forward on the basis of Fourier transform according to the principle of spectrum analysis. Forging process of steel 45 gear blank with the pre-forging and finish forging is simulated, and correlative field variables of forging and die are analyzed, in conclusion, reasonable pre-forging die cacity profile is obtained. Forging process of gear blank with the pre-forging and without pre-forging is simulated and the results indicate that, compared with the forging without pre-forging, the maximal equivalent stress and equivalent strain of the forging with pre-forging minish, the transition region is more obvious and broader, the forming of materials is more even, the distribution and flow of materials are more reasonable, the performance of filling die is enhanced, so the possibility of preform design method on the basis of equipotential field method and local smoothness treatment method on the die cacity profile on the basis of Fourier transform is proved, and the reliability of their results also is proved.更多还原