基于仿真技术的汽车拼焊板冲压成形研究

运用DYNAFORM软件对低碳钢材料拼焊板进行冲压成形仿真研究,直观地了解成形过程.通过对仿真后的成形极限图进行分析,发现初始条件下的设计方案导致破裂和起皱这两种缺陷.因此对冲压成形的工艺条件进行适当调整,提出改进的设计方案,再次进行仿真,最终提高了冲压成形质量.研究表明,合理选取冲压速度、增设开放式拉延筋可以有效地解决拼焊板冲压成形过程中的破裂和起皱这两种缺陷.     

不等厚拼焊板材的成形性实验研究

不等厚拼焊板由于焊缝的存在及其方位影响，又由于坯料强弱不均，可以引起坯料的冲压变形性能发生显著变化。本文通过焊接工艺对比，比较了激光焊、滚压电阻焊和氩弧焊工艺对拼焊板塑性变形性能的影响；对拼焊板试析进行拉伸实验，确定了焊缝方位和薄厚板比例对试件塑性变形的影响；进行了不等厚拼焊板件的半球拉深实验和方盒件拉深实验，总结了拼焊板材的冲压成形性能和不均匀变形规律。     

压边力对拼焊板制汽车流水槽成形性能的影响

基于有限元仿真软件DYNAFORM,以异种材料相等厚度的拼焊板成形某汽车流水槽本体为对象,建立了有限元仿真模型,对该零件的拉延过程进行模拟,研究不同压边力及几种典型变压边力对冲压成形性能的影响。结果表明,压边力对零件拉延成形过程中起皱和拉裂等缺陷的产生有很大影响,适当的压边力能有效抑制各种缺陷的产生。     

激光拼焊板典型零件冲压缺陷分析及改进

针对异强度双相钢激光拼焊板冲压开裂的问题,使用Autoform软件模拟了前大梁零件的成形过程,研究了不同位置材料减薄率、应力、应变的变化规律。通过单一变量试验方法研究了压边力、n值、r值对焊缝开裂的影响规律。结果表明：焊缝处坯料前期受到成形力和压边力的作用,后期主要受到DP780双相钢位移的拉应力,导致焊缝处坯料受到的拉应力大于DP590双相钢成形力,使得焊缝坯料的塑性应变和厚度减薄率迅速增大,发生开裂。当压边力优化至1500 kN时,零件不开裂,并在生产中验证了模拟结果;DP780双相钢的n值、r值对零件焊缝处坯料的减薄率影响不明显,DP590双相钢的n值、r值对零件焊缝处坯料的减薄率影响明显,当r值≥1.4或n值≥0.19时,零件不开裂。     

基于应变路径的拼焊板盒形件成形性能研究

利用Dyanform对拼焊板盒形件进行冲压成形数值模拟,研究不同压边力对拼焊板盒形件拉深过程中破裂危险点应变路径和成形性能的影响规律;同时,提出台阶式变压边力控制方法.结果表明:通过调整压边力的大小和变化方式,可以实现对拼焊板盒形件破裂危险点处应变路径的控制以及减小焊缝移动,从而提高拼焊板盒形件的冲压成形性能.     

拼焊板方盒件冲压成形压边力数值模拟分析

用有限元分析软件Dynaform对拼焊板方盒件成形进行数值模拟,研究不同压边力对拉深过程中破裂危险点应变路径和焊缝移动的影响规律。通过调整压边力的大小和变化方式,可以实现对拼焊板方盒件薄板破裂危险点处应变路径的控制以及减小焊缝移动,从而提高拼焊板方盒件冲压成形性能。     

拼焊板冲压成形与焊缝移动机制分析

拼焊板冲压成形机理很复杂,该文以横向和纵向焊缝U形件及盒形件为例,主要采用数值模拟的方法,从压边圈的类型及其压边力的大小和分布、焊缝的位置和方向、应力应变的分布等角度进行分析,从简单的横向和纵向焊缝U形件出发,研究盒形件拼焊板金属流动和焊缝移动机制.研究分析了横向焊缝移动和纵向焊缝移动原因和移动趋向;分析了盒形件的底部、裙边和侧壁焊缝与U形件焊缝移动异同,并结合压边力、焊缝的原始位置等因素研究分析了盒形件的底部、裙边和侧壁上的焊缝移动的原因和规律.     

基于拉延筋和压边力的差厚拼焊板拉延成形回弹预测与控制

利用有限元模拟预测了拉延筋和压边力对双焊缝差厚拼焊板汽车纵梁成形回弹的影响.找出了成形中减少回弹的方法.结果显示,设置拉延筋或增大压边力可以在一定程度上减小回弹量.在设置拉延筋和总压边力不变的条件下,在不同厚度板料部分施加不同的压边力使回弹得到了有效控制.     

压边力对双焊缝差厚拼焊板拉延成形焊缝移动的影响

拼焊板在拉延成形时焊缝移动受多方面因素的影响,本文模拟分析了不同压边力值和分段压边力对具有两道焊缝的差厚激光拼焊板汽车后纵梁在拉延成形过程中焊缝移动的影响。通过分析在不同压边力下两条焊缝的移动量得出了焊缝最大移动量随压边力的增大而增大的规律。为了减小两条焊缝的移动量,成形过程中在保证总压边力不变的情况下对差厚拼焊板的不同板厚部分设置不同的压边力。通过模拟分析得出了焊缝最大移动量随着薄侧压边力的增大和厚侧压边力的减小而减小。合理的增大薄侧板料压边力,减小厚侧板料压边力可以减小焊缝移动量,提高成形质量。     

镁合金拼焊板冲压成形过程数值模拟

借助MSC-Marc模拟软件,采用大变形弹塑性有限元法,建立了镁合金拼焊板筒形件冲压成形有限元模型,对相同厚度、不同成分的镁合金拼焊板冲压成形过程进行了数值模拟。得到了筒形件底部及侧壁法兰处焊缝移动规律;分析了压边力及板料初始温度对焊缝移动情况的影响。对于拼焊板冲压成形的研究具有一定意义。     

镁合金拼焊板焊接性能及覆盖件冲压成形

采用钨极交流氩弧焊的焊接方法成功制备0.8mm厚的AZ31和AZ80镁合金拼焊板,确定了钨极交流氩弧焊接工艺参数。经过300℃×60min退火热处理后,使镁合金拼焊板焊接接头平均晶粒度从23μm细化到16μm。对0.8mm厚的AZ31、AZ80镁合金拼焊板冲压成形,当AZ31薄板的温度范围在190℃～210℃,AZ80薄板的温度范围在310℃～350℃时的成形效果良好。在成形件底部,焊缝向塑性较差的AZ80材料侧偏移,最大移动距离为0.55mm。     

液压夹紧装置在差厚激光拼焊板冲压中的研究

破裂和焊缝移动是差厚激光拼焊板成形中存在的两个主要问题.利用塑性力学,对焊缝移动进行了力学分析.为提高激光拼焊板的成形性能,设计了液压夹紧装置,并解释了装置的原理.通过门内板拼焊板的冲压成形实验,比较了使用液压缸前后拼焊板的焊缝移动变化和板厚变化情况.实验表明,夹紧装置能有效地控制差厚拼焊板成形中焊缝的移动,能减少薄侧板材的变薄,从而提高拼焊板的整体成形性能.     

基于变压边力技术的微车大梁回弹研究和控制

回弹是微车大梁冲压成形过程中的主要质量缺陷之一,直接影响到冲压件的尺寸精度和零件最终形状.为了有效地控制回弹,基于变压边力技术对某型微车右后大梁的冲压过程进行了设计和仿真,并对仿真结果进行了分析.结果表明,压边力变化的范围越大,零件的回弹量越小.最后,提出了一种可应用于工程实践的变压边力优化方法,并在微车右后大梁的回弹控制上进行了应用,起到了很好的效果,使右后大梁最大开口回弹角由之前的8°减小到了2°.     

Microstructural and mechanical investigation of aluminum tailor-welded blanks

The push to manufacture lighter-weight vehicles has forced the auto industry to look to alternative materials than steel for vehicle body structures. Aluminum is one such material that can greatly decrease the weight of vehicle body structures and is also consistent with existing manufacturing processes. As in steel structures, cost and weight can be saved in aluminum structures with the use of tailored blanks. These blanks consist of two or more sheets of dissimilar thicknesses and/or properties joined together through some type of welding process. This enables the design engineer to “tailor” the blank to meet the exact needs of a specific part. Cost savings can be gained by the elimination of reinforcement parts and the stamping dies used to manufacture them. Weight savings can be attained based on the fact that one thicker piece is more efficient than a welded structure and therefore can allow for down-gauging of parts. Although tailor-welded blanks (twbs) offer both potential weight and cost benefits, the continuous weldline and thickness differential in twbs can often result in difficulty in stamping. This problem is more severe in aluminum because of its limited formability as compared with typical drawing-quality steels. Additionally, welding of steel twbs tends to increase the strength of the weld material, which helps prevent failure in the weld during forming. Aluminum twbs do not experience this increase in strength and therefore may have a greater tendency to fail in the weld. In this study, several aspects of twbs manufactured from 6111-T4, 5754-O, and 5182-O aluminum alloys were analyzed and compared with those of a more conventional steel twb. The effect of gauge mismatch on the formability of these blanks is discussed as well as the overall potential of these blanks for automotive applications.     

随行程变化变压边力拼焊板盒形件成形性能研究

焊缝两侧材料变形不均匀引起的焊缝移动和成形性能下降是拼焊板成形过程中需要解决的难题,变压边力技术可以增大成形工艺调整范围、提高冲压件成形质量。本文在拼焊板成形过程中加载随行程线性渐增变化的变压边力,并应用动力显式数值模拟软件模拟差厚拼焊板盒形件的成形过程,研究变压边力控制对拼焊板成形性能的影响。结果表明,在相同的焊缝移动量下,线性渐增变压边力与定常压边力相比增大了引起焊缝移动的薄侧变形区域材料的长度,缓解了薄侧材料的应变集中,提高了拼焊板成形性能。     

Variable blankholder force in U-shaped part forming for eliminating springback error

Springback is the main defect in U-shaped part forming, which can badly affect the shape of a part. Applying reasonable variable blankholder force in the forming process is one of the useful methods to solve this problem, but determination of the curve of blankholder force vs. punch displacement is still difficult. A method is advanced in this paper to control the forming process of a U-shaped part, by which a reasonable blankholder force curve can be easily gained. Comparing with constant blankholder force, higher forming quality can be obtained in both avoiding cracking and improving dimension accuracy. The benchmarks of the 2D draw bending problem in NUMISHEET’93 has been utilized to validate the method by FEM, and good results of springback elimination have been obtained.     

Stamping and stamping simulation with a blankholder gap

Applying a blankholder gap is the main method of control of the blankholder in stamping or its simulation. In this paper, the nature of stamping with a blankholder gap is provided as well as two advantages of stamping simulation with a blankholder gap. Finally, a reasonable blankholder gap for cup deep drawing and the reverse drawing process is proposed.     

Experimental investigation on high strength steel (HSS) tailor-welded blanks (TWBs)

This paper aims to investigate mechanical characteristics of the new tailor-welded blank (TWB) components made of high strength steel (HSS). A series of HSS-TWB thin plates with different orientations of weld line are studied through three-point bending tests to evaluate the effects of different design parameters, such as weld line locations and material combinations, on the deformation behaviors. The experimental results exhibit good repeatability of tests. And the relative shift phenomenon between indenter and specimen is observed and analyzed for the TWB steel sheets with different weld line orientations at parallel and 45° to the bending moment, respectively. The results from the experiment include the force versus displacement curves and some detailed photographical images throughout the loading process. It is found that the discrepancy of different combinations is quite noteworthy. In this paper, the peak force, absorbed energy and bending strength are presented to evaluate the mechanical characteristics of HSS-TWB thin plates with different weld line orientations and material combinations. The comparison demonstrates that the TWB structures with the weld orientation at 45° angle to the bending moment have the greatest advantages of different TWB steel sheets.     

曲线焊缝差厚拼焊板冲压性能研究

目前对于曲线焊缝拼焊板的研究和应用还比较少,对其成形规律还不清楚。文章通过曲线焊缝拼焊板的半球胀形试验及有限元仿真,得出相对于其他类型曲线焊缝拼焊板而言,圆弧焊缝拼焊板有较好的冲压性能的结论;并探索了圆弧焊缝拼焊板的焊缝半径与焊缝移动和成形高度之间的关系,导出了相关的数学表达式,为生产实际提供了理论指导。     

Eliminating springback error in U-shaped part forming by variable blankholder force

Springback is the main concern in U-shaped part forming, which would adversely affect desired part geometries. The use of variable blankholder force in the forming process is one effective method to reduce springback. However, there has not been a systematic way to determine the blankholder force trajectory. In this article, a methodology of obtaining this blankholder force trajectory in forming a U-shaped part that considers the wrinkling limit and fracture limit in the forming process was proposed. The method was validated numerically by using the Finite Element Method to simulate the benchmark of a 2-D draw bending problem in NUMISHEET’93. With the calculated blankholder force trajectory, higher forming quality was obtained and compared with constant blankholder force cases. Springback was kept at a minimum while avoiding cracking.