内高压成形技术现状与发展趋势

介绍了内高压成形原理 ,工艺分类、优点、应用范围和适用材料 ,综述了国外内高压成形在工业领域尤其汽车工业的应用情况 ,给出了用内高压成形制造的典型结构件、枝杈管件、异形管件和空心轴类件。详细介绍了国内研制的 4 0 0MPa内高压成形机参数及在该设备上试制的铝合金管件、不锈钢管件、空心阶梯轴和轿车后轴纵臂等内高压成形件。最后指出内高压成形需要深入研究的课题和发展趋势     

不锈钢卡压式管件的成形工艺

基于建设部2001年颁布的《不锈钢卡压式管件》标准,介绍了三通、弯头、直通等型式管件的塑性成形模具、关键工艺流程及工艺参数。文中所介绍的模具及工艺均适用于大批量生产,且管件成形精度好,模具成本低,综合效率高。     

7A04铝合金复杂零件的超塑性成形工艺研究

用超塑性成形工艺对外侧表面带凸耳的空心圆锥体铝合金(7A04)零件进行了成形试验,通过分析和试验确定了合理的超塑成形工艺和模具结构。该零件须分两步进行超塑成形:先成形空心圆锥体,再成形凸耳;超塑性成形工艺制造该零件比原机加工工艺简单,节省材料超过60%。     

塑性加工领域的新进展

尽管电子信息(IT)产业近一时期以来得到迅猛的发展,与此同时材料制备与加工领域也出现了许多新技术,其根本动力是产品不断更新的需求牵引了相应的新工艺的出现,例如电子器件与医疗器械的发展促进了微成形技术的发展;汽车的结构轻量化带动了内高压成形技术的开展;航空薄板件的成形近来出现可变模腔的成形;在导弹行业,薄壁高温合金已成功地应用了粘性介质压力成形。还应强调的是以上这些新工艺的实施也是用高新技术武装传统行业的重要标志。     

轿车后轴纵臂内高压成形研究

用400MPa内高压成形机对轿车后轴纵臂进行内高压成形试验研究,设计了合理的模具结构,包括分模面和冲头密封形式。分析了矩形截面圆角成形特点和所需成形压力计算公式,制定出合理的内高压工艺和参数,成功地试制出轿车后轴纵臂,经检测尺寸满足设计要求。     

汽车行业中管件液压成形技术的新进展

管件液压成形技术作为汽车零件减重的重要方法之一 ,近几年发展很快 ,国外多个汽车公司已将其应用于管类零件的生产。主要介绍了该技术的工艺特点 ,国内外应用情况与相关研究成果。     

多点成形--金属板材柔性成形的新技术

多点成形是一种板材三维曲面柔性成形的新技术.简述了多点成形的基本原理与系统构成并介绍了几种成形方式.在多点成形中,厚板曲面件可直接成形,薄板曲面件则采用柔性压边技术进行成形.利用多点成形技术的柔性特点还能实现分段成形、反复成形、多道成形以及闭环成形等新的板材成形工艺.     

金属板料的激光冲击成形技术

介绍了金属板料激光冲击成形技术的系统组成、成形原理、技术特点 ,以及影响板料激光冲击成形的主要因素。指出了激光冲击成形技术在工业中应用所必须研究的一些主要内容。     

不需要冲孔由实心毛坯锻制空心产品的技术

该技术的核心是用实心坯料锻制空心件 ,使用的工艺为径向锻造工艺。其原理是通过控制压缩形式进给量和推压形式 ,从而使芯部产生高应力 ,超越应力极限 ,产生内部变形 ,从而出现空心 ,这种工艺可锻制多种高塑性材料。其主要用途是锻制承受扭矩的空心轴 (如电机轴 ) ,节约材料 ,提高工件强度 ;生产高液压瓶体 ;生产1 5ｍｍ× (1 0 0 0～ 1 2 0 0 )ｍｍ管材 ,壁厚可达 2 0～ 1 0 0ｍｍ ;生产钻机下水管及各种专用空心管件 ;用于改善芯部毛坯的金属结构。其经济效益与钻孔工艺相比 ,材料节约 3 0 %～ 5 0 % ,生产空心产品劳动力低 ;减少锻造力…     

SPF/DB在空心叶片制造中的应用

主要介绍了超塑性成形和扩散连接 (SPF/DB)技术在夹心结构空心叶片制造方面的应用 ,前、后缘以及局部形状设计要求 ,叶片的厚度分布、金相组织、机械特性和可行的工艺流程     

Part 1: Analytical modeling of symmetric multi-nose tube hydroforming

Part 1 of this series of papers presents an analytical model for a multi-nose tube hydroforming process based on a mechanistic approach. In this process, the tube is surrounded by a number of evenly distributed circular dies. The model was established based on equilibrium conditions, yielding criteria, geometrical relationships, and a volume constancy condition. The system of equations was derived and solved for various process parameters. The model validation was performed using finite element analysis and experiments. The model has the ability to predict process parameters such as stresses, strains, internal pressure, geometry variables, and thinning rate distribution. The model could be applied to regular planar tube hydroforming of polygonal shapes such as square, pentagon, or octagon. Details for establishing governing relationships for polygonal shape hydroforming from the multi-nose analytical model are given in Part 2 of this series of papers.     

Hydroforming of locally heat treated tubes

In tube hydroforming, the process chain can be very long as it may involve several pre-forming operations (e.g. bending, crushing, end forming, etc.) which are usually followed by an intermediate annealing stage. Conventional annealing is performed in batches and it is often perceived as a long, relatively expensive and non-environmentally friendly operation. For this reason, in this paper local intermediate heat treatment is proposed as a promising alternative solution, in order to reduce the throughput process time. The study has been carried out on a real tubular motorcycle part, by performing both experiments and numerical simulations, in order to verify whether local annealing can be an effective substitute of conventional global annealing. Several alternative ways of locally heat treating an Al6060 tube right before hydroforming have been investigated. The results demonstrate that a feasible solution can be found, with local heat treatment of relatively small portions of the tube.     

Part 2: Analytical modeling of regular planar polygon tube hydroforming as a special case of symmetric multi-nose tube hydroforming

Part 2 of this series of papers presents an analytical model for regular planar polygon tube hydroforming (THF) as a special case of the analytical model for symmetric multi-nose tube hydroforming. The governing equations derived for multi-nose THF in Part 1 were evaluated by taking the limit of die geometric variables, resulting in a new set of governing equations for regular polygon THF. The model was validated using finite element analysis and a THF experiment, where good agreement was obtained. The model is able to predict field variables such as stresses and strain distribution, thinning rate distribution, and deformed shape at a particular pressure.     

Failure analysis of hydroforming of sandwich panels

Sandwich panels are commonly used in various applications to improve the stiffness-to-weight ratio of structure components. While producing flat sandwich panel is relatively straightforward, manufacturing of shaped sandwich components can be a challenging task. This paper presents the use of hydroforming technique in forming bi-layered and sandwich materials with an open-cell foam core. Hydraulic bulge experiments were conducted to form bi-layered and sandwich blanks into a dome shape. Various failure modes were observed from the experiments. Finite element simulations were conducted to understand the different failure mechanisms that could occur during the deformation process. The investigation can facilitate the selection of geometry and property of the constituents of the sandwich material for successful hydroforming.     

圆管弯曲加工过程的数值模拟

采用显式有限元分析软件LS -DYNA ,对于圆形钢管的弯曲加工过程进行数值模拟。圆管弯曲加工模型是常见的回转引伸弯曲加工方式 ,并在分析模型中考虑了阻止钢管在弯曲加工过程中起皱和截面扁平化的芯轴 ,以及为了防止钢管弯曲的外侧的壁厚过分减薄在钢管的末端加上压力。通过数值模拟得到管壁的最大减薄和增厚部位 ,并讨论了芯轴的摩擦系数和钢管末端的压力对管壁厚度变化的影响。     

用增量网格法对空心复合挤压的实验研究

用增量网格法对带内孔坯复合挤压的载荷、上下通道流出量、金属内部应力应变分布情况进行实验分析,并分析内孔直径和凹模锥角等参数的影响,对设计模具与选择成形设备有指导意义.文中还阐述这种实验方法的实施过程和功能,指出这是一种研究成形问题的有效手段.     

钛管的一次压扁成形工艺

此文研究了钛管装入聚胺脂芯棒后一次压扁成形的工艺特点,分析了以往空心管成形所存在的问题。在实验的基础上完成了不同规格钛合金管材的一次压扁成形。     

The strain gradient approach to predict necking in tube hydroforming

A stress-based forming limit diagram for necking prediction which is based on the strain gradient theory of plasticity in conjunction with the M–K model has been represented and used in tube hydroforming. In this study, the finite element model for bulge forming of straight tube has been constructed and verified with published experimental data. The adaptive simulation technique is based on the ability to detect the onset and growth of defects (e.g., wrinkling, and bursting) and to promptly readjust the loading paths. Thus, a suitable load path has been obtained by applying Adaptive Simulation Method in ANSYS Parametric Design Language (APDL).