拼焊板车门内板冲压成形工艺研究

采用数值模拟软件Dynaform5.5对某拼焊板车门内板的拉深成形工艺进行研究,探讨不同压边力和拉延筋对该复杂曲面零件成形性能以及焊缝移动的影响规律。通过调整压边力和拉延筋等工艺参数得到了成形性能较好且焊缝移动趋势较小的车门内板零件。     

激光拼焊板前纵梁拉延成形数值模拟研究

在分析激光拼焊板汽车前纵梁成形工艺的基础上,基于DYNAFORM软件平台对前纵梁零件的拉延成形过程及不同工艺参数对成形结果的影响进行了数值模拟研究。针对模拟结果中零件出现的缺陷,提出了初步的工艺改进方案。     

板料成形拉延筋技术研究现状

拉延筋在汽车覆盖件拉深成形中起着十分重要的作用.利用拉延筋可以调节和控制板料的变形程度和变形分布,抑制破裂、起皱、面畸变等多种冲压质量问题的产生.在很多情况下,拉延筋的设置合理与否将决定覆盖件拉深的成败.较系统地总结了板料成形拉延筋技术以及拉延筋作用原理、阻力模型、影响因素等的研究现状.     

双相钢激光拼焊板温成形拉深性能分析研究

板料的温塑性成形方法已经得到广泛使用,可以运用到双相钢激光拼焊板成形中以提高其成形性能。以盒形件为分析对象对双相钢激光拼焊板的温拉深性能进行了研究,通过温单拉实验、盒形件温拉深过程的有限元模拟与实冲实验以及金相实验,分析了双相钢激光拼焊板由常温到500℃各个温度下的力学性能与拉深性能。结果表明:成形温度对双相钢激光拼焊板温拉深影响比较显著,在400～500℃温度范围内进行温成形,能获得较好的成形性能。     

拼焊板焊缝方向对其单向拉伸性能的影响研究

为提高拼焊板成形性,用单拉实验来研究拼焊板焊缝方向对其拉伸性能的影响.采用解析、实验和有限元法研究了拼焊板焊缝方向对其综合延伸率、失效模式的影响.结果表明,当焊缝角度较小时,失效表现为焊缝开裂;随着焊缝角度增大,平均延伸率非线性减小,且变化速率逐渐减小.当焊缝角度超过一定值后,失效变为薄侧母材开裂,并随着焊缝角度增大拼焊板综合延伸率逐渐增大,且增大的速率逐渐减小.在失效模式转换时,焊缝角度相应存在一个临界点,这一临界角度大小主要依赖于焊缝和薄侧母材性能.适当的焊缝角度有利于拼焊板成形性能的提高和失效模式的控制.     

基于数值模拟的盒形件拉深成形变拉深筋技术研究

以盒形件为研究对象,建立了盒形件拉延筋成形的数值模型,分别对盒形件固定拉深筋和变拉深筋成形进行了数值模拟研究,并进行了工程试验的验证,对结果及误差进行了分析,实现了基于拉深筋高度变化的变拉深筋技术.这种方法能有效发挥板料成形性能,提高零件拉深成形质量.     

高强度钢-普通钢拼焊板热冲压成形机理研究

目的 研究高强度钢-普通钢拼焊板热冲压成形机理.方法 对高强度22MnB5钢-Q235钢拼焊板高温力学性能及U形热弯曲件的微观组织和力学性能进行实验研究,对高温下拼焊板协调变形进行数值分析,研究拼焊板高温力学性能和热弯曲件微观组织、力学性能的影响机制及拼焊板热变形协调机制.结果 焊缝与拉伸方向平行时,800℃下拼焊板伸长率不高,两侧母材形变量相差较大;900℃和950℃下,两种母材形变量接近.焊缝与拉伸方向垂直时伸长率较低.热弯曲件"软"、"硬"区抗拉强度差为500～1000 MPa,伸长率差为5％～20％.结论 焊缝与拉伸平行时拼焊板塑性较好,温度越高焊缝两侧变形较一致,焊缝与拉伸垂直时拼焊板力学性能主要取决于"软"区母材的性能.揭示了高强度22MnB5钢-Q235钢拼焊板热冲压成形机理.     

轻量化拼焊板构件塑性成形研究进展

拼焊板构件因容易实现轻量化、低成本、短周期成形制造而被广泛应用于飞机、汽车工业中,但在这类构件的塑性成形中,焊缝引入的材料、几何、边界条件非线性显著增加了成形复杂性,导致成形质量及成形极限下降,尤其是在具有强烈不均匀变形特征的弯曲、旋压等局部加载塑性成形中表现得更加明显,极大制约了轻量化拼焊板构件的精确塑性成形。为此,国内外学者在拼焊板构件弯曲及旋压变形机理与成形规律方面开展了大量研究。从焊接材料不均匀力学行为表征、拼焊板构件弯曲及旋压成形有限元建模、焊缝特征对变形行为影响及工艺设计等方面综述了相关研究进展,最后提出了拼焊板构件塑性成形仍面临的关键难题与挑战,对认识和发展轻量化拼焊板构件塑性成形具有重要指导意义和参考价值。     

汽车前围板冲压数值模拟及工艺参数优化

针对汽车覆盖件冲压过程变形复杂的特点,对某型号汽车前围板零件拉深过程进行数值模拟,分析压边力及拉延筋的变化对该零件成形效果的影响.通过成形极限图优化压边力及拉延筋,最终获取该零件拉深工序合适的工艺参数,为汽车覆盖件冲压工艺提供快速、有效的设计方法.     

拼焊板焊接工艺及其对拼焊板塑性变形影响的试验研究

通过拼焊板试件拉伸试验对拼焊板的塑性变形性能进行了分析研究 ,讨论了拼焊板的几种实用焊接技术 ,给出了拼焊板的机械性能参数 ,比较了焊缝处于拉伸试样不同位置时拼焊板与母材的拉伸试验结果 .分析了焊缝分布对拼焊板塑性变形性能的影响 ,以及如何优化焊缝位置以提高拼焊板的整体塑性变形能力 .     

激光拼焊 Boron 钢板热冲压性能研究

以无镀层和Al-Si镀层Boron钢板为研究对象,分别采用激光拼焊技术制作成多段式坯料,应用已有热冲压模具生产零件。通过对基板和焊缝的力学性能、金相组织和断面硬度的分析,比较了激光拼焊无镀层和Al-Si镀层Boron钢板热冲压性能的区别。     

An experimental analysis of drawing characteristics of a dual-phase steel through a round drawbead

The sheet drawing characteristics of a dual-phase steel (DP600) through a round drawbead are determined experimentally using strip drawing tests. For this purpose, a drawbead simulator is designed and integrated with a standard tensile testing machine. Drawing tests are conducted with steel strips cut from 1 mm thickness blanks. The strip geometries, thickness strains, pulling forces and clamping forces are measured during drawing through a round drawbead of 5 mm bead and shoulder radius. The drawbead force parameters and thinning strains are determined from measurements. The experiments are repeated with conventional draw-quality sheets (DC06) of the same thickness for the purpose of establishing a benchmark database. A comparison of calculated drawing characteristics between two types of steels indicates the significant differences in terms of drawbead force parameters. In addition, analysis of experimental data demonstrated bead penetration, clamping force and material flow stress as the dominant factors on drawbead restraint force and blank thinning deformation for both materials. The results of experimental analyzes for both steel types can employed as model input curves for equivalent drawbead models in FE process simulations.     

双相钢激光拼焊板温拉伸流变应力模型研究

在通过温拉伸实验获得的真实应力-应变曲线的基础上,采用Zener-Hollomon参数的双曲正弦形式来建立双相钢激光拼焊板温拉伸条件下的流变应力模型,方程中材料参数通过最小二乘法线性回归获得,并将其表示成应变的多项式形式,从而使此模型适用于整个应变过程中.流变应力的预测值与实验值吻合较好,预测的最大相对误差为6.27%,最大均方差为8.718MPa,从而验证了双相钢激光拼焊板温拉伸流变应力模型的准确性.     

Weld zone representation methods during the stretching of friction stir welded blanks with dissimilar sheet thickness: A study using numerical simulations

In this work, the validity of weld zone representation as single zone or double zone under varied weld conditions of friction stir welded (FSW) blanks with dissimilar thicknesses sheets is explored. During LDH test simulations, representative base material of 1.5 mm and 1.1 mm thickness is considered. It is observed that modeling FSW blanks with double zone assumption plays a vital role for accurate formability prediction. There are possibilities of obtaining multiple domains of weld conditions for the single zone and double zone assumption validity. The failure locations also affect the weld zone representation along with the critical error percentage difference between reference model (single zone) and double zone model FSW blanks. The number of single zone models has increased in transverse weld orientation and number of double zone models has increased in longitudinal weld orientation in the case of FSW blanks with dissimilar thickness as compared to similar thickness FSW blanks. A comparison is done between the limit strain values for single zone and double zone assumptions with reference model. The pattern that is observed in the load‐punch stroke behavior is also seen in limit strain comparison for weld zone representation.     

Geometry evolution of rail weld irregularity and the effect on wheel-rail dynamic interaction in heavy haul railways

Rail welded joints are important structural connections in the formation of continuous welded rail (CWR). Due to the difference in the stiffness and material at rail welded joints, rail damage and geometric degradation will occur and evolve under repeated train loads, which will significantly influence the wheel-rail dynamic interaction. In this paper, geometric measurements of the rail surface are made at the single flush welding zone by a tracking test on Datong-Qinhangdao heavy haul railway line in China. Fractal geometry theory is applied to calculate the fractal dimension and describe the geometric evolution of rail weld irregularities. Then, the vehicle-track coupled dynamic model is used to investigate the effect of the geometric evolution of rail weld on the wheel-rail dynamic interactions both in the time and frequency domains. The calculation results show that rail weld irregularities have fractal characteristics due to the fractal dimension of measured geometries mostly larger than 1.1. The geometry evolution of rail welded irregularity has great effects on the wheel-rail dynamic interactions in the time domain, but has little effects in the frequency domain. Fractal geometry theory can be used to describe the geometry evolution of rail weld irregularity and the effect on the wheel-rail dynamic interactions. The results can provide novel ideas for the evaluation and evaluation of the rail weld irregularity.     

Effect of differential heat treatment on the formability of aluminium tailor welded blanks

Tailor welded blanks (TWBs) are blanks that are tailor made to suit the required function. They are made by joining blanks of different thicknesses, materials, coatings, etc. The forming behaviour of such TWBs will be different from the conventional blanks, as TWBs with different strength levels will be subjected to the same forming loads but will result in unequal deformation values. The present work is aimed at studying the formability behaviour of TWBs of two different materials namely AA6061 and AA2014. The blanks were made by friction stir welding process at different rotational speeds, welding speeds and tool tilt angles on a vertical head milling machine. The formability of the TWBs and the base materials has been studied before and after solution heat treatment and analysed with the help of Limiting Dome Height (LDH) test. A differential heat treatment approach has been followed, which is unique in this work. From the results, it was found that the formability of heat treated TWBs were higher than those of base materials and untreated TWBs.     

TA2纯钛板钨极氩弧焊接接头组织与性能

本文研究了不同焊接工艺下焊缝及热影响区的微观组织特征,以分析焊接接头的力学性能。结果表明焊缝组织为锯齿状α相、板条α相及少量针状马氏体,并得到焊接最佳工艺为焊接电流85A,焊接速度0．5cm／s,主喷嘴氩气流量20L／min,拖罩氩气流量12L／min,双面焊接。此焊接工艺下得到的焊接接头抗拉强度达到母材的99．55％,延伸率达到母材的70％。文中还探讨了焊后热处理对焊接组织与性能的影响,结果表明焊后热处理可以提高焊接接头的塑性,可以调整焊接接头的综合力学性能,使其达到使用标准。     

Experimental and numerical studies on the forming behavior of tailor welded steel sheets in biaxial stretch forming

Stretch forming is an important process in making complex stampings for autobody components. In the present work formability of three different types of tailor welded blanks (TWBs) in biaxial stretch forming modes has been studied by conducting limiting dome height (LDH) tests. The TWBs are laser-welded samples of low carbon and ultra low carbon steel sheets with difference in thickness, grade and surface conditions. In TWBs with difference in thickness, the LDH decreases as the thickness ratio increases and the thickness of the thinner side is also crucial. A high thickness ratio causes two major strain peaks on thinner side and fracture takes place due to strain localization at the peak close to the pole. The weld ductility and the extent of difference in properties are the two crucial parameters for formability in TWBs with difference in properties. In both these TWBs, the fracture takes place perpendicular to the weld line and propagates towards the stronger side. Significant weld line movement occurs towards the thicker/stronger side in biaxial stretch forming. The maximum weld line movement occurs at the pole and it increases with increase in thickness ratio and becomes constant beyond a certain thickness ratio. The peak load required to deform the TWB specimens is less compared to the corresponding parent sheets. In case of TWBs with difference in thickness, as the thickness ratio increases, the peak load reduces due to decreasing punch-blank contact area.