Hole flanging with cold extrusion on sheet metals by FE simulation

Flange height and lip thickness are generally restricted by the formability of sheet metals in the conventional hole flanging operation. In the current work, cold extrusion was applied and a special forming die set was designed with a stripper subjected to counter-pressure with an aim to obtain a more substantial flange. FEM software DEFORM was utilized to simulate this flange extrusion process with two forming conditions: forming with a fixed die cavity and forming with the stripper subjected to counter-pressure. The results showed the cup preform tended to buckle on its bottom with insufficient counter-pressure. The cup preform would start extruding a flange when critical counter-pressure was reached. The magnitude of the critical counter-pressure increased in flange extrusion of smaller inner diameters. The corresponding overall forming load was greatly reduced as compared to flange extrusion with a fixed die cavity.     

锥台形空心件挤压工艺与模具设计

锥台形空心件形状比较特殊，其成形工艺和模具也有其特点。本文论述了锥台形空心件挤压成形工艺和模具设计要点，给出了实用的模具结构。     

影响冷挤模寿命的因素

介绍了影响冷挤模寿命的几个因素，并且就这些影响因素产生的原因，以及如何克服进行了分析和阐述，为在生产中及时排除这些影响因素起到了很好地借鉴作用。     

关于提高活塞销冷挤压凸模寿命的研究

在简要分析了活塞销冷挤压必要性的基础上，对活塞销冷挤压技术在国内的发展历史及其现状进行了讨论。明确指出妨碍活塞销冷挤压技术在国内推广应用的关键因素是其冷挤压凸模的寿命太短。深入分析了活塞销冷挤压时金属的流动规律，作用在凸模上的力和凸模失效的原因。提出了提高活塞销冷挤压凸模寿命的方法。     

大高径比空心锻件冷挤压成形工艺分析及有限元仿真

采用冷挤压与冲裁相结合的新形工艺方法成形大高径比空心锻件，不仅大大提高生产效率，而且产品性能也远远高于热锻产品。通过有限元对整个变形过程的模拟，可动态观察整个变形过程应力、应变以及速度场的变化情况，从而为金属塑变过程流动规律的分析提供强有力的理论支持，并为优化工艺方案提供参考依据。实验结果同有限元仿真结果的很好吻合，不但充分证明该工艺方案的可行性，而且为该类零件的生产提供一种新思路。     

扁翼类零件挤压成形数值模拟及缺陷预测

采用基于Euler网格的有限体积法(FVM)对扁翼类零件的冷挤压成形过程进行数值模拟，研究变形过程中金属质点的流动情况与等效应变情况，分析挤压后期金属的应力矢量情况，为工艺改进和优化模具设计提供理论依据。总结出具有扁翼特征的零件在成形中变形区范围和变形程度的变化规律，揭示出扁翼类零件变形的不均匀性；预测出扁翼类零件的扁翼端部尤其是端部上顶面是可能出现成形缺陷的部位，这一结论得到了相关实验研究的验证。     

An investigation on the hot extrusion process of magnesium alloy sheet

This study investigates the hot extrusion of magnesium alloy sheets at various temperatures, material, speed and lubricant. A multi-speed method is applied to extrude a magnesium alloy sheet at a high extrusion ratio. The experimental results are analyzed to optimize the processing conditions, increase the tensile strength and reduce the extrusion load on the magnesium alloy thin sheet. Nowadays, most magnesium alloy products are manufactured by industrial die casting. Hot extrusion is seldom used to finish magnesium products because the extrusion speed, temperature and extrusion load significantly effect the properties of the product. In this study, the Taguchi experimental method with the orthogonal array is applied. ANOVA is used to investigate how parameters affect the extrusion process. All possible mechanical properties of the product are analyzed to obtain the optimal process parameters. In addition, magnesium alloys with different compositions are experimentally tested to determine the mechanical properties of the extruded product and obtain the relationship between the process parameters and the properties of the material.     

活塞销冷挤压模具设计

分析了活塞销的冷挤压工艺,设计了活塞销冷挤压模具。该模具通用性强,只需更换模具的少量零件,就可挤各种型号的活塞销。该冷挤压工艺节约了大量原材料和加工工时,强化了产品力学性能,从而大大提高了产品的市场竞争力。     

Deformation analysis of hole flanging with ironing of thick sheet metals

The objective of this paper was to investigate the characteristics of hole flanging with ironing of thick sheet metals. A number of experiments were pertbrmed by using a conical punch. Several blanks of different thickness which were made from commercially pure aluminum were used. A lubricant based on aluminum fluoride and metallic stearate was applied to both sides of the blank. The effects of blank thickness on the punch load and the finished shape in the hole flanging with ironing were investigated. The experimental results were compared with the simulated results obtained by the rigid-plastic FEM. The results have demonstrated that the rigid-plastic FEM can be used effectively for predicting the punch load and the finished shape.     

弹壳零件冷挤压复合工艺分析

分析了弹壳类零件的成形特点,比较了3种成形工艺方案,对复合挤压成形方案进行了数值模拟,并制定了多次挤压的方案。为弹壳类零件的挤压成形提供了有益参考。     

超越齿轮冷挤压复合成形工艺的有限元模拟

对超越齿轮的冷挤压成形方案和改进后的方案进行有限元模拟分析，确认在挤压过程中出现的上部内腔底部塌陷和下部齿裂的原因是由于工件中心部分金属流动较快造成的，从而对生产工艺进行了改进并进行计算机模拟，以此确定挤压后合理的预制坯形状和模具结构。最后指出工艺与模具设计和仿真并行，可有利保障生产工艺的可行性和模具设计的可靠性。     

Electro-hydraulic forming of sheet metals: Free-forming vs. conical-die forming

This work builds upon our recent advances in quantifying high-rate deformation behavior of sheet metals, during electro-hydraulic forming (EHF), using high-speed imaging and digital image correlation techniques. Aluminum alloy AA5182-O and DP600 steel sheets (1 mm thick, ∼152 mm diameter) were EHF deformed by high-energy (up to ∼34 kJ) pressure-pulse in an open die (free-forming) and inside a conical die. The deformation history (velocity, strain, strain-rate, and strain-path) at the apex of the formed domes was quantified and analyzed. The data shows that the use of a die in the EHF process resulted in an amplification, relative to free-forming conditions, of the out-of-plane normal velocity and in-plane strain-rate at the dome apex. This amplification is attributed to the focusing action of the die on account of its conical geometry. Further, while the strain-path at the dome apex was generally linear and proportional, the use of a die resulted in greater strain at the apex relative to the strain during free-forming. The sheet deformation profile in the EHF process was found to be different from that previously observed in electromagnetic forming (EMF) and, thus, the two processes are expected to result in different strain-paths and formability. It is anticipated that quantitative information of the sheet deformation history, made possible by the experimental technique developed in this work, will improve our understanding of the roles of strain-rate and sheet-die interactions in enhancing the sheet metal formability during high-rate forming.     

国内外冷挤压技术发展综述

阐述了冷挤压技术的特点 ,介绍了国内外冷挤压技术的发展过程 ,分析了冷挤压技术的发展趋势 ,并针对该技术存在的问题提出了建议。     

小型薄壁套管多工位冷镦挤工艺

小型薄壁套管类零件,整体尺寸较小且内外结构复杂,加工方法的选择和成形工艺设计方面是生产该类零件的重点和难点。针对上述难点,采用适合中小型零件批量加工的多工位冷成形加工方法,并根据成形理论分析,初步设计出两种较合理的六工位冷成形方案,对成形过程采用Deform-3D软件数值模拟。得出先反挤压成形薄壁端的最大载荷为5.6×104N,远小于先镦粗成形凸缘的最大载荷;台阶深孔的成形采用杯-杯复合挤压,其损伤值远小于材料的临界损伤值。最终通过生产试验验证模拟结果的最佳工艺,且成形后小型薄壁套管的内部组织分布合理,无冷镦缺陷。     

弹壳类零件冷挤压复合成形工艺研究

弹壳类零件具有壁薄、底厚的结构特点，为了提高其组织致密度和机械性能，宜采用冷挤压工艺生产该类零件。本分析比较了这类零件成形的几种工艺方案，指出复合冷挤压工艺具有工序少、制件尺寸精度高、壁厚均匀、模具结构简单、造价低的优点，是弹壳类零件较好的一种成形方法。采用2D体积成形分析软件MAFAP模拟了其复合冷挤压过程，通过批量试生产及金相分析，制制未产生缺陷，表明弹壳类零件的复合冷挤压工艺是合理可靠的。     

用于金属冷挤压成形的三维操作机器人

介绍了用于金属冷挤压成形的三维操作机器人的工作过程、结构与控制系统。     

汽车异形齿类零件复合挤压成形技术的优化

分析了汽车零件中1种异形齿形类零件,即离合器轮毂类零件的结构特点及其复合冷挤压成形加工工艺的技术难点,详细阐述了此种类型零件复合冷挤压成形技术的模具设计要点,以及模具的加工、安装和调试。针对现有复合冷挤压成形技术存在的问题,提出了改进优化的方案,设计了改进优化的凹模、凸模以及坯料,通过试验验证了优化的效果。     

冷挤压模具失效分析与提高模具寿命途径

本文系统分析了影响挤压模具寿命的各种因素,从设计选材、减少挤压件壁厚、模具表面强化处理等方面,阐述了提高挤压模具寿命的途径.     

Experiment investigation of deep-drawing sheet texture evolution

To ensure the deep-drawability of the deep-drawing sheet, the normal anisotropy and planar isotropy of the sheet is required. The drawing property of the sheet is controlled by its crystallographic texture, the type and orientation density of the texture directly influence the drawing-quality of deep-drawing sheet. {1 1 1}1 1 2 and {1 1 1}1 1 0 are the ideal textures for deep-drawing sheet, because the correct texture gives the proper orientation of slip system so that the strength in the thickness direction is greater than that in the plane of the sheet. During the production processing of the deep-drawing sheet, the development of crystallographic texture is continuous, and the final texture character of the product is determined by the texture evolution processing at the different technological process. In the present work, the whole production flow of a coiled sheet has been flowed in Benxi Iron and Steel (Group) Co., Ltd., and the samples were cut from this coiled sheet at the different production flow, such as after hot rolling, cold rolling and recrystallization annealing, respectively. The texture evolution processing has been investigated for the whole production flow of the deep-drawing sheet. Some factors that influence the evolution of the crystallographic texture have been analyzed, such as the grain size of hot-rolled sheet, the reduction ration in the cold rolling, the annealing process, the precipitation of AlN during the coiling and, etc. This paper centers on the research of the texture evolution in each different process. An optimum technique to improve the deep-drawability of the deep-drawing sheet has been put forward.     

冷挤压组合凹模的机械可靠性设计理论的研究

在分析了冷挤压组合凹模传统设计问题的基础上，根据组合凹模的受力情况，应用机械可靠性理论，首次提出了按组合凹模过盈量进行可靠设计的思想，首次建立了组合凹模机械可靠性设计的整套理论。