提高开口拉伸成形性的模具设计方案

在车身制件冲压工艺设计中,为减小材料尺寸,提高材料利用率,开口拉伸是常见的工艺方案,但其弊端就是会使制件成形不充分,从而影响制件强度及品质。介绍了通过特殊的模具结构来弥补开口拉伸成形不充分的弊端,并通过常见制件的实际案例。阐述了该模具结构对提高制件成形性的有效性,实现了采用开口拉伸提高材料利用率的同时,又保证了制件成形充分。为汽车冲压模具设计提供了新思路,降低冲压件生产成本提供了新渠道。     

深拉伸模气冷系统技术的开发运用

汽车行业中冷冲压深度拉伸模,无论是高于行业标准拉伸深度200mm的二次拉伸模,还是普通的深度拉伸模冲压成形时,都有走料严重发热现象。且深度拉伸模工作时走料深度深,摩擦大,冲压件受到的应力大。摩擦发热不仅仅影响冲压件板材性能,同样影响模具的材质性能,会减少模具的使用寿命并且不可预料的造成冲压件拉毛、缩颈、开裂、起皱等质量缺陷,在模具生产冲压件中后期尤为明显。故开发运用了冲压深度拉伸模气冷系统,最终解决了深度拉伸的冲压件质量问题,延长了模具和设备的使用寿命。     

多工序冲压成形工件的技术经济性分析

以分析影响冲压件成本的因素为基础,就排样与材料利用率、冲压件的结构工艺性和多工序冲压成形工艺方案等方面分析探讨了基于多工序冲压成形的冲压件的技术经济性。     

复层板材冲压件废次品实例分析

用实例对钢／铝复层板材在拉伸──胀形复合成形中出现的起坡和破裂、钢／聚氯乙烯覆膜板在冲裁中出现的覆膜鼓起和大毛刺等现象进行分析。讨论了材料、模具结构、操作方式和热处理工艺等因素对冲压件的影响及解决的措施。     

高温合金冲压件翻孔成形工艺改进研究

GH536高温合金具有良好的热加工性能,但其在冷成形过程中易出现加工硬化现象。使用GH536高温合金材料的高翻边孔冲压件在一般翻孔工艺成形过程中,会出现翻孔边缘开裂和翻孔竖边高度达不到要求的问题。通过分析冲压件在一般翻孔工艺过程中产生以上问题的原因,对一般翻孔工艺进行改进,采用先拉伸再冲孔后翻孔的新工艺。使用DYNAFORM软件模拟冲压件在新工艺条件下的翻孔成形过程,并根据材料变形的特点及翻边孔的质量,确定翻孔工艺的新方案,解决高温合金材料的高翻边孔冲压件在翻孔成形过程中孔开裂和翻孔竖边高度达不到要求的问题。     

侧围外板零件典型开裂与改善

汽车侧围外板零件是车身重要的冲压件之一,成形过程极其复杂,拉伸过程中易产生起皱、开裂、凹坑等缺陷。文章针对侧围外板最常见的开裂缺陷问题,通过网格应变分析技术,研究B柱下区域变形特征和材料发生减薄、开裂的原因;基于有限元仿真模型,系统研究板料尺寸和拉延筋阻力对拉伸破裂的影响规律,并提出调整方案;由现场生产验证了分析结果的准确性和修模方案的有效性。     

端盖成形工艺分析及模具设计

通过对端盖冲压件进行成形工艺分析，阐述了零件在拉伸成形过程中的特点，并制定出合理的工艺路线，设计了2副模具成形，满足了产品的设计要求。     

预成形件对超高强钢板热冲压减薄率的影响

为了降低超高强钢板在热冲压过程中的减薄率,以车轮侧盖为研究对象,设计了4种预成形件结构方案,通过有限元模拟分析预成形件形状、尺寸对减薄率的影响,基于模拟结果,进行了预成形件热冲压实验。结果表明:热冲压件的显微组织为板条马氏体,显微硬度达到460 HV以上;零件球窝处材料减薄率最大,预成形有利于降低材料减薄率;预成形件储料面积越大,热冲压件材料减薄率越小;预成形件为深度为22.8 mm的圆拱形储料结构且切角时,材料减薄率最小,为11.67%,壁厚均匀性较好。实际热冲压实验结果和数值模拟结果基本一致。     

大厚度双曲度铝合金飞机蒙皮拉伸成形工艺优化

拉伸成形工艺是飞机蒙皮零件的基本成形方法.针对某大厚度双曲度铝合金飞机蒙皮进行了拉伸成形工艺研究和优化.为了保证数值模拟的准确性和可靠性,进行了材料性能测试试验,获取了该蒙皮多道次加工时每一道次、不同热处理状态下的材料性能.通过数值模拟,研究了拉伸成形工艺参数包括各道次拉伸量、上模压力、合模间距对贴模和回弹的影响规律....     

温度和压边力对高强度硼钢热冲压成形板厚的影响

针对高强度硼钢板热冲压成形过程中厚度分布不均匀的问题,对它的成形过程进行了数值模拟,结合实验研究了初始成形温度和压边力对热冲压件板料厚度的影响规律。结果表明:初始成形温度850℃、压边力70MPa时,材料成形性能较好。在该工艺条件下获得了合格制件,验证了模拟结果的可靠性。     

Observations on the Influence of Tool-Sheet Contact Conditions on an Incremental Forming Process

The influence of tool-sheet contact conditions on features such as surface roughness, forming force, and formability was evaluated for components produced by incremental forming, a highly flexible innovative sheet metal-forming process. Experimental tests were carried out on sheets of AA7075T0 to create two types of component: pyramid frusta (for the evaluation of roughness and force) and cone frusta (for the evaluation of formability). Four different types of tool-sheet contact were analyzed, using two types of tool. From the experimental tests, the influence on the surface finishing and on the trend of the forming forces depending on contact type was revealed. Contact types do not, however, influence sheet formability.     

材料参数对模拟件冲压成形的影响

在对模拟成形进行成形特征分析的基础上，研究了特定成形方式下材料参数对冲压成形性的影响规律。     

A new formability indicator in single point incremental forming

Material properties play an important role in determining the sheet fracture in metal forming processes. However, the degree of influence of a material property on the forming extent depends on the nature of the forming process employed. In the current study, the effect of various material properties on the formability in SPIF has been investigated. Correlations of the formability with material properties under investigation were developed in order to establish a new formability indicator. An empirical model describing the effect of the newly introduced formability indicator has also been proposed.     

基于板料成形有限元仿真技术的空调面板优化设计

以空调面板为研究对象,对其成形过程进行数值模拟,研究了产品圆角半径对成形性能的影响,分析了零件在不同冲压速度条件下的成形安全性,通过实际生产验证了优化结果的可行性及有效性。     

超声振动效应对TA2钛合金板材力学及胀形性能影响

针对钛合金板材塑性变形能力差的问题,进行了超声振动辅助成形工艺的研究,分析超声振动对钛合金TA2板材力学性能及与接触面之间摩擦系数的影响。在此基础上进行了不同宽长比坯料的超声振动辅助胀形实验,分析超声振动对TA2板材胀形力、极限胀形高度的影响。同时,基于网格应变原理,通过不同宽长比坯料极限应变的测量,建立TA2板材的成形极限图。研究结果表明,选择合适的超声振动辅助成形工艺参数, 不仅可以提高TA2板材变形能力,还可以减小摩擦对板材成形性能的影响,从而有效提高了TA2板材的成形极限。     

结合齿冷锻工艺分析及参数优化

利用Deform-3D软件对结合齿的冷锻成形过程进行了模拟,应用正交模拟试验以及工程试验相结合的方法,对某汽车变速箱结合齿冷锻工艺及参数优化进行研究,对预成形制件主要几何参数进行优化。研究结果表明:采用制定的冷锻预成形加精整倒锥工艺是可行的;凸台直径是影响成形力大小的最主要因素,其次是圆角半径,而齿形长度、内孔直径及凸台长度对成形力的影响较小;优化结果是当齿形长度A=6.5mm、内孔直径B=45mm、凸台直径C=62mm、凸台长度D=11mm、圆角半径E=2mm时,成形载荷最小。以优化结果为依据,成功实现了该类零件的冷锻成形。     

Influence of mechanical properties of the sheet material on formability in single point incremental forming

New trends in sheet metal forming are rapidly developing and several new forming processes have been proposed to accomplish the goals of flexibility and cost reduction. Among them single point incremental forming operations, in which the final shape of the component is obtained by the relative movement of a simple and small punch with respect to the blank, appear quite promising.In the paper, material formability issues in incremental forming were studied. Some relevant correlations among material formability and other mechanical properties of the material were analysed. The FLD₀ value, i.e. the major strain at fracture in plane strain conditions, was determined for different materials and the influence of the main material parameters on formability was accurately investigated through a statistical analysis.     

Mechanism investigation for the influence of tool rotation and laser surface texturing (LST) on formability in single point incremental forming

Single point incremental forming (SPIF) is a new sheet metal forming process which achieves higher formability, greater process flexibility and reduced forming force compared to conventional sheet forming operations due to its characteristic of localized deformation. In recent years, a novel SPIF process assisted by localized friction heat is developed to further improve the material formability. Physically, the frictional heat is generated by the high relative motion at tool–workpiece interface resulted from tool rotation. However, the mechanisms behind formability difference induced by tool rotation at both low and high speed ranges are required to investigate in detail. In this paper, a series of experiments with an increase of tool rotation speeds ranging from 0 to 7000 rpm are conducted to form AA5052-H32 aluminum alloy sheets into a truncated funnel. Additionally, the obtained results are analyzed in terms of formability, forming forces and temperature trends to find out the different roles of friction and heat during the forming process. As a result, the formability behaviors at varying tool rotation speeds can be categorized into four stages according to different reasons. It indicates that friction is the dominant factor in low tool rotation speed range (0–1000 rpm) but will be substituted by thermal effect and potential dynamic recrystallization in high tool rotation speed range (2000–7000 rpm). Furthermore, due to the proved lubrication enhancement and hydrodynamic enhancement generated by surface textures, a laser surface textured forming tool is also utilized to show its influence on forming forces, measured temperatures and the corresponding formability. Finally, it demonstrates that the fabricated laser surface texturing (LST) is capable to reduce the friction at tool–workpiece interface and change the magnitude of heat generation.     

拼焊板盒形件冲压成形失效及应变路径分析

采用自制液压机和分瓣压边圈模具,通过模拟仿真和实冲试验,变化各工艺参数,研究分析拼焊板方盒件冲压成形的应变路径、焊缝移动和成形极限,以提高其成形性能。研究表明,厚/薄侧压边力的大小和分布对破裂危险点的应变路径和成形裕度有很大的影响,合理的压边力分布可调节失效破裂的位置,减少焊缝移动和提高成形极限深度;凹模圆角半径的增大,对薄侧侧壁圆角处破裂危险点应变路径影响较大,拼焊板盒形件成形极限深度逐渐增大;厚度比较小时,破裂出现在薄侧圆角处,而厚度比较大时,焊缝移动量大,破裂易出现在薄侧焊缝处;板料毛坯形状和尺寸对失效破裂的位置和成形性能影响显著。因此,以薄侧侧壁圆角处和薄侧焊缝位置附近为破裂危险点,通过优化压边力、凹模圆角半径、板料厚度比、板料毛坯形状和尺寸等工艺参数,改变危险点的应变路径,调节失效破裂的位置,减小其焊缝移动量,可有效地提高拼焊板方盒件的冲压成形性能。     

Influence of weld geometry and mismatch on formability of aluminium tailor welded blanks: numerical and experimental analysis

Abstract

The forming behaviour of tailor welded blanks (TWBs) has been widely studied since its development. In the numerical simulation studies, the TWBs are modelled as blanks composed of two different materials, and often, the presence of the weld bead is neglected in its finite element discretisation. In the present work, the influence of the weld bead shape on the formability of friction stir welded TWBs, is analysed. Several finite element meshes were constructed in order to represent different weld bead geometries and numerical simulations of the cylindrical cup drawing were performed. Strong influence of the weld bead shape on the formability of the TWBs was observed when the weld was in overmatch relatively to the base material, and little influence when the weld was in undermatch condition. Comparison of the numerical results with experimental ones shows that the numerical analysis is able to preview the formability of the TWBs.