基于模型特征优化钛合金热成形试验研究

钛合金钣金支架件因局部形状突变,成形困难易起皱。采用数值模拟,分析了毛坯形状、模具尺寸对零件起皱缺陷的影响。利用零件展开逆向修正优化,结合试验,在原毛坯缺口处设计有开口的新毛坯;考虑模具材料与钛合金线热膨胀系数差,设计模具尺寸,并进行了650、660、670和680℃下的热成形试验。结果表明,在板料变形集中处开口,能消除成形中起皱缺陷;成形温度影响零件成形品质,温度低、起皱未完全消除;温度高,表面优化加重,成本高,最佳成形温度为670℃。     

物理逆向法在优化钣金成形毛坯中的应用

钣金成形中毛坯形状直接影响工件的成形和材料的流动情况,因此优化毛坯设计非常重要,不仅可以得到高质量的零件,而且节省材料和成本。文章介绍了关于‘物理逆向法’的进一步工作,提出了适合生产应用的加热装置。并通过有限元模拟和试验,对比研究了几何法、有限元一步法、物理逆向法确定毛坯的合理性。结果表明,物理逆向法适合毛坯的优化,对于盒形件,该方法与有限元一步法效果接近,而且明显优于几何法。     

钣金成形毛坯展开方法研究进展

钣金成形中毛坯形状的确定是一个重要的工艺环节。该文对各种传统的毛坯确定方法进行了分析综述;对近年发展的确定毛坯的各种方法进行了分析对比。通过分析认为,有限元法将成为确定毛坯展开形状的主要方法,物理逆向法可能成为一种行之有效的方法,而传统方法将逐渐被淘汰。     

基于有限元反向法的板料成形毛坯设计

由反向法计算出的毛坯存在一定的形状误差。为获得优化的毛坯 ,根据冲压件成形后的形状误差和变形趋势 ,提出了毛坯形状修正算法。结合Hyperform和Dynaform软件应用所提出的毛坯形状修正算法实现了毛坯设计方法。数值模拟结果表明 ,这种设计方法具有较高的精度和计算效率的同时 ,还可以评价冲压件的成形性。     

管筒形零件机械扩径工艺过程的成形参数优化

管筒形零件机械扩径最终制品的横断面尺寸精度和形状精度,不同程度地受到各种工艺参数、模具参数、材料性能参数以及摩擦条件的影响。机械扩径工艺设计的重要内容之一,就是针对特定的毛坯规格,合理选择各种成形参数并使其成为一种最优组合,以获得最佳的制品尺寸和形状精度。文章基于MSC.Marc非线性有限元分析软件和遗传优化算法,应用Python语言设计了机械扩径成形参数优化的遗传算法程序,通过对MSC.Marc软件的二次开发,实现了遗传优化算法与MSC.Marc软件的连接,为管筒形零件机械扩径工艺过程的成形参数优化提供了一种新方法。针对大直径管线钢管机械扩径工艺,得到了以最终制品形状精度(横断面圆度误差)为优化目标的扩径率、模具直径和模具边缘圆角半径等成形参数的最优组合。采用最优的成形参数组合,可以显著提高最终制品的横断面形状精度。     

分块压边条件下毛坯形状对矩形件成形性能的影响

利用有限元软件ANSYS/LS-DYNA分析了在分块压边条件下不同的毛坯形状对矩形件拉深成形性能的影响。模拟结果表明:在变压边力成形过程中,毛坯形状对零件成形性能有着重要的影响,优化后的毛坯可以显著改善矩形件的成形性能。     

基于CAE的汽车支架成形前的带孔板材毛坯设计方法研究

以某汽车支架零件的成形工艺为例,研究了特殊形状结构零件在"先落料冲孔,后弯曲成形"的成形工艺中存在的侧冲孔废料难以卸除及模具寿命低等问题.分析了带孔板料毛坯在冲压成形过程中产生的变形对成形件质量的影响,以确保成形件的结构形状尺寸能够满足图纸要求.利用基于CAE(Computer Aided Engineering)的钣金成形有限元分析FASTFORM软件,根据成形件的数模及成形材料的属性,逆向展开输出成形产品精确的带孔板料毛坯,将数值模拟结果产生的板料毛坯的边形与孔形尺寸,作为落料冲孔模具凸、凹模的边形与孔形的设计依据,可有效缩短该类模具的设计周期,降低生产成本,提高产品质量与企业的市场竞争力.     

Influences of blank shape on the forming property of rectangular parts under segmented blank holder

利用有限元软件ANSYS/LS-DYNA分析了在分块压边条件下不同的毛坯形状对矩形件拉深成形性能的影响.模拟结果表明:在变压边力成形过程中,毛坯形状对零件成形性能有着重要的影响,优化后的毛坯可以显著改善矩形件的成形性能.     

洗手盆工艺参数模拟优化设计

针对不锈钢洗手盆的结构特点,分析计算其主要工艺参数及毛坯尺寸,运用Dynaform成形分析软件对其进行模拟,分析零件的成形工艺及其起皱、破裂缺陷,通过对毛坯形状、拉深筋尺寸及位置、模具间隙、工艺切口、润滑等进行优化,避免了成形过程中的缺陷,获得了理想的毛坯形状和工艺参数。     

复合板油底壳拉延成形研究

介绍了复合减振钢板油底壳拉延成形研究的意义,同时针对复合板材料上下两层板在拉延过程中不允许错动的特点,进行了油底壳结构工艺性分析及结构形状优化.在分析、研究材料的力学性能、相对厚度、凹模圆角半径、压边力、拉延筋、毛坯形状尺寸、润滑等关键技术和工艺参数的基础上,确定了油底壳成形工艺方案.通过在模具上实际生产,验证了复合板油底壳拉延成形工艺参数的正确性.     

Accurate optimization of blank design in stretch flange based on a forward–inverse prediction scheme

This paper presents a forward–inverse prediction scheme that combines explicit dynamic finite element method (FEM), true strain method (TSM), and adaptive-network-based fuzzy inference system (ANFIS) to determine the anisotropic optimum blank in stretch flange process. It is not easy to guess the blank shape in stretch flange process using traditional trials. The forward–inverse prediction scheme can efficiently determine the optimum blank and improve the shrink phenomenon of the flange target. In the present study, the initial shape of the nearby optimum blank could be predicted quickly by the forward scheme of TSM at first. Then, several blanks with parallel curves to this shape are created and analyzed by explicit dynamic FEM to establish the training database for the inverse scheme of ANFIS. From the hybrid-learning algorithm, ANFIS can be efficiently trained for the optimum blank shape, and the prediction knowledge rule database can be accomplished. Using the trained ANFIS, the exact optimum blank shape of stretch flange can be inversely predicted more correctly and efficiently. Moreover, the stretch flange experiments are performed using non-optimum and optimum blanks. It also shows that a good agreement is achieved from comparison between simulated and experimental results, such as punch load, punch stroke and deform shape. From this investigation, the forward–inverse scheme is proved to be able to supply a useful optimum preform in the metal forming category.     

板料成形过程中合理毛坯形状的确定

为了提高产品质量和降低生产成本 ,需要合理确定成形件的毛坯形状。在介绍目前几种确定合理毛坯形状方法的基础上 ,提出用形状误差来优化由几何映射法获得的初始毛坯 ,进而确定合理的毛坯形状。以方盒件为例进行了数值模拟和物理模拟 ,结果表明 ,该方法确定的毛坯成形时避免了成形缺陷 ,而且修边余量小 ,既提高了质量又降低了成本 ,因而此方法是一种确定毛坯的有效方法     

一步成形有限元法在确定毛坯初始形状中的应用

一步成形有限元法，是从产品的形状出发，将其作为成形后工件的中面并对其离散，通过有限元方法确定在满足一定边界条件下，工件中的节点在初始毛坯中的位置。由一步成形有限元法可以得到对应的毛坯形状，通过计算毛坯结点到工件上的位移可得到工件上的应力和应变。此法计算速度快，不需要模具和工艺信息，建立分析模型简单，可用于板料成形设计早期，用来估计零件的成形性能。     

轴对称拉深件多步反向模拟方法研究

针对轴对称拉深件多步反向模拟问题，以理想成形理论为基础，采用直线和圆弧作为基本线素，根据母线对于轴对称拉深件、中问过渡形状以及毛坯进行描述，建立供节点移动的滑移线。根据零件的轴对称性质，采用对数应变以及R.Hill48厚向异性屈服准则对径向、周向、厚向应变以及等效应变进行描述，在此基础上，构建了以初始构形上的节点坐标为基本未知量的有限元方程。通过求解上述有限元方程得到了满足理想成形条件的节点坐标，以及应变分布规律。通过实际应用，该算法简单易行，计算效率高。     

Design and analysis of new test method for evaluation of sheet metal formability

A new test method including the tool shape and test procedure was developed to evaluate sheet metal formability using the finite element method (FEM). This method is intended to generate the various modes of deformation and to control the onset of failure independently under each mode so that the forming limit diagram (FLD) achieves a good representation of a wide range of strains.A blank holder force-punch stroke diagram with three failure loci is introduced to define the optimum process condition and the formability index by which each material is quantitatively evaluated. The test procedure of this method consists of three steps: drawing a blank holder force (BHF)-punch stroke diagram, measuring strains from the part stamped at the optimum process condition, and grading the test materials using the formability index. In numerical simulations under optimum process conditions, sheet metals can fail due to multi-mode rupture; this failure leads to a widely balanced strain distribution in the FLD such that strains are developed near the forming limit over a wide range of forming modes.Experiments were conducted on three grades of steel sheets to validate the proposed method. Stamping results yield well-defined strain signatures having a wide range of strain distribution in the FLD in all materials tested. The outcomes of the shape and strain behaviors agree well with the numerical results.     

Blank design for deep drawn parts using parametric NURBS surfaces

Deep drawing is a forming process controlled by a number of parameters. The initial blank shape is one of the most important process parameter that has a direct impact on the quality of the finished part. This paper describes a new method to determine the optimal blank shape for a formed part using the deformation behaviour predicted by finite element simulations and salient features of NURBS surfaces. The proposed optimization method involves an initial blank shape, which is iteratively trimmed according to the deep drawing simulations results, to achieve the final optimal blank shape. The deep drawing simulations were carried out using DD3IMP, an implicit in-house finite element code. Parametric NURBS surfaces are used to optimize the initial blank shape based on the deformation behaviour predicted by numerical simulation. The proposed method can determine the optimal blank shape for any part within a few iterations.     

多点位控制压边数值模拟研究

板料冲压成形的主要缺陷是起皱和撕裂 ,当模具的几何形状确定后 ,压边力是关键的成形控制参数 ,它不仅是凸模行程或时间的函数 ,还应随压边位置的不同而变化。确定拉深过程中板料各部位所需压边力的变化规律 ,可实现压边力的优化控制 ,对复杂拉深件如汽车覆盖件的成形尤为有利。该文以非轴对称抛物面车灯反光罩为例 ,采用DYNAFORM软件对其成形过程进行了数值模拟 ,比较了均布控制压边力和多点位控制压边力对成形的影响