镁合金手机壳的温热液压成形实验及模拟研究

通过对镁合金手机壳进行温热液压成形实验及有限元模拟,分析了液压加载与冲头运动的不同匹配关系对成形结果的影响,以及成形过程中缺陷产生的原因,并确定了合适的成形工艺参数,即在170℃,控制冲头速度在0.2mm/s~1mm/s,液压载荷不低于5MPa,能一次完成成形底部带斜面,并具有较小圆角半径的镁合金手机壳。液压载荷应在坯料的拉深高度小于3mm时快速的施加,否则,在成形件的底部一平面和斜面与棱边交界处将形成难以消除的堆积缺陷。模拟结果与实验吻合良好。研究表明,温热液压成形可以实现常温或低温液压成形难以实现的复杂镁合金零件成形。     

C10100铜合金管挤压成形过程的有限元模拟

研究挤压成形工艺中的挤压速度、挤压温度和凹模圆角半径各工艺参数对挤压件成形质量的影响规律。采用有限元模拟软件Deform-2D建立了C10100铜合金的热挤压有限元模型,坯料的成形流变性能按其数学模型从该模拟软件数据库中选取。选择挤压速度分别为40,50和60 mm·s-1,挤压温度为850,900和950℃,凹模圆角半径为10,15,20和25 mm,比较在不同挤压参数下的等效应变值与最大挤压力值的差异。研究结果表明,当最佳工艺参数为:挤压速度50 mm·s-1、挤压温度950℃、凹模圆角半径10 mm时,所得到的挤制管材的表面光洁度及内部组织满足工程应用要求。     

基于Kriging模型的超高强度钢板热冲压工艺参数优化

为了改善超高强度钢板冲压件的加工质量,以某方形槽热冲压件为对象,以板料淬火温度、模具初始温度、冲压速度和模具间隙为设计变量,以冲压件成形温降、回弹量和成形减薄率3个质量指标为响应量,构建了热冲压加工质量指标的Kriging模型。在此基础上,以构建的Kriging模型为目标函数,建立超高强度钢板热冲压工艺参数多目标优化模型。应用第二代非支配遗传算法进行寻优计算,获得了优化的热冲压工艺参数:B1500HS超高强度钢板零件热冲压的最佳淬火温度为898.3℃,模具的初始温度为67.1℃,冲压速度为39.64 mm·s-1,模具间隙为2.2 mm。工艺参数优化后的验算结果表明,工艺参数优化后,成形温度更加均匀,回弹量减少25.6%,最大减薄率下降23%。     

基于Dynaform的印涂铝盖拉深速度的数字化设计

在非线性有限元软件Dynaform平台上,以1725印涂铝盖首次冲压拉深成形为例,在保持其他工艺参数不变的条件下,对不同拉深速度下的冲压拉深成形过程进行了数值模拟。结果表明:1725印涂铝盖首次冲压拉深能避免拉裂现象的速度范围为2000~6000 mm·s-1(不包括2000和6000 mm·s-1)。研究了最大壁厚、最小壁厚、最大壁厚与最小壁厚的差值,以及增厚率、减薄率、竖直壁的厚度方差等参数的变化规律,结果发现:1725印涂铝盖首次冲压拉深的合理的速度范围为4000~5500 mm·s-1,其中,4000 mm·s-1是更为理想的拉深速度。最后通过生产试验证明,拉深速度为4000 mm·s-1时可以生产出质量较为理想的合格产品。     

平底简形件板材液压成形的数值模拟

针对传统板材冲压成形中存在的成形极限低、模具凹模复杂及零件表面品质差等缺点,发展了板料液压成形技术。通过数值模拟方法,采用钣金成形专用分析软件JSTMPA／NV对5754铝合金平底筒形件的板料液压成形过程进行了研究,以最终成形零件的壁厚分布为评定标准,对成形过程中零件可能出现的缺陷进行预测和分析,研究工艺参数包括充液室压力、凸凹模单边间隙和凹模圆角半径对零件成形性的影响,并对工艺参数进行了优化。研究表明：采用20MPa的液室压力、1．1mm的凸凹模单边间隙和5mm的凹模圆角半径时,获得的铝合金平底筒形件的     

汽车蓄能器壳体件挤压成形工艺研究

基于Deform-3D软件平台,通过数值模拟对汽车蓄能器壳体件的挤压成形过程进行工艺优化。建立正交试验方案,分析各个因素对挤压成形过程的影响,以成形载荷作为评判标准确定了最佳工艺参数组合。通过实验最终得到了最佳成形工艺参数为:温挤压模具温度230℃,温挤压坯料温度1000℃,温挤压摩擦系数0.15,温挤压凸模速度12mm.s-1,冷挤压凸模速度8mm.s-1,冷挤压摩擦系数0.08。按照该工艺参数进行实际零件的挤压生产,最终得到了符合要求的成形零件。     

基于HyperXtrude的ZK60镁合金型材挤压成形数值模拟和实验验证

应用Hyper Xtrude软件对ZK60镁合金空心型材的挤压成形过程进行了有限元数值模拟研究,分别得到了型材在稳态挤压下的温度场、速度场、应变场和位移场,分析了金属流动情况、焊合室入口和出口处的压力。通过不同挤压速度下的稳态模拟分析,确定了合适的型材挤压速度为10 mm·s-1。在挤压温度为350℃和挤压速度为10 mm·s-1条件下进行实验验证,得到了形状外观均合格的产品。对比分析发现,模拟结果与实验结果的型材断面宏观组织形貌具有一致性,证明了应用Hyper Xtrude软件可以有效预测镁合金型材成形过程中的金属流动和焊合情况。     

AZ31镁合金板材温热冲压数值模拟与实验研究

采用Gleeble3500热模拟实验机进行了单向拉伸实验,分析了AZ31镁合金板材的力学性能;以此实验数据为基础,对温热冲压过程进行了数值模拟,研究了拉深温度、压边力等工艺因素对镁合金板材成形性能的影响;通过极限拉深比实验,对数值模拟结果进行了实验验证。结果表明:在极限拉深温度150℃,极限拉深速度15 mm/s,固定压边力的工艺条件下,极限拉深比能够达到2.5。模拟结果表明:模拟结果和实验结果具有良好的一致性;采用变压边力可以明显提高板材的冲压性能,极限拉深比将达到5.0。     

6061高强度铝合金拉深工艺参数优化

基于DynaForm对6061高强度铝合金板料拉深成形过程进行仿真模拟,通过设计正交试验,研究在不同温度、压边力、冲压速度下的拉深件成形质量,采用极差与方差分析了3个工艺参数的影响程度,并对该影响因素进行了优化分析。研究结果表明:最佳的成形工艺参数为,400℃的试验温度、8 kN的压边力和4 mm/s的冲压速度。     

冲压速度对DP780双相钢和304不锈钢胀形性能影响的试验对比分析

利用速度可控的小松伺服压力机对双相钢DP780与304不锈钢1 mm板料进行杯突试验,根据杯突试验值Er的大小来研究冲压速度对试验结果的影响。对比双相钢DP780及304不锈钢两种材料的试验结果发现,在冲压速度由3 mm·s-1增大到30 mm·s-1的过程中,304不锈钢杯突值从9.39 mm降低到8.59 mm,双相钢DP780杯突值从7.53 mm降低到7.39 mm。此实验结果使速度对材料拉胀成形性能的影响得到确认,即在3~30 mm·s-1区间内,随着冲压速度的升高,材料杯突值不断减小,材料的抗破裂成形性能逐渐降低,即材料的拉胀成形性能降低。     

铝合金圆锥形零件粘性介质温成形研究

采用热力耦合有限元数值模拟方法对铝合金圆锥形零件粘性介质温成形过程进行了模拟分析,研究了成形过程粘性介质和板材的温度分布、不同温度条件下成形零件壁厚分布、成形载荷等.结果表明,圆锥形零件的底部圆角区域为成形危险区域.非等温粘性介质温成形过程中,在粘性介质内部形成的非均匀温度场影响了板材的温度分布.当粘性介质温度略低于板材温度时,坯料中心区域温度较低,有利于延迟底部圆角成形时的破裂,提高了零件壁厚的均匀性.分别进行了室温和加热时铝合金圆锥形零件粘性介质压力成形试验,试验结果与数值模拟具有相同的规律.     

基于Abaqus的汽车板快速冲压有限元分析

基于Abaqus/Explicit动力显式有限元方法,分析了不同冲压速度下的某汽车覆盖件在冲压成形过程中节点速度、应变速率的分布规律.结果表明:随着冲压速度的提高,在变形过程中节点速度基本呈现增高的趋势,特别是变形较复杂的区域.同时,指出为了能更准确地模拟实际冲压过程,有限元材料模型中应采用应变速率大于10-2 s-1获得的力学性能参数进行研究,以便更准确地反映实际材料特性.     

5A06-O aluminium–magnesium alloy sheet warm hydroforming and optimization of process parameters

The uniaxial tensile test of the 5A06-O aluminium–magnesium (Al–Mg) alloy sheet was performed in the temperature range of 20–300 °C to obtain the true stress–true strain curves at different temperatures and strain rates. The constitutive model of 5A06-O Al–Mg alloy sheet with the temperature range from 150 to 300°C was established. Based on the test results, a unique finite element simulation platform for warm hydroforming of 5A06-O Al–Mg alloy was set up using the general finite element software MSC.Marc to simulate warm hydroforming of classic specimen, and a coupled thermo-mechanical finite element model for warm hydroforming of cylindrical cup was built up. Combined with the experiment, the influence of the temperature field distribution and loading conditions on the sheet formability was studied. The results show that the non-isothermal temperature distribution conditions can significantly improve the forming performance of the material. As the temperature increases, the impact of the punching speed on the forming becomes particularly obvious; the optimal values of the fluid pressure and blank holder force required for forming are reduced.     

Parametric analysis of warm forming of aluminum blanks with FEA and DOE

1 Introduction Warm forming of lightmass materials has been investigated as an alternative manufacturing process to achieve higher formability compared with forming at room temperature due to a substantial increase in material ductility[1?8]. SHEHATA et a…     

Evaluation of stamping lubricants in forming advanced high strength steels (AHSS) using deep drawing and ironing tests

In forming AHSS, the lubricant must reduce the friction between die and sheet as well as the effect of heat generated from deformation and friction, especially in forming at high stroking rates. In this study, the effectiveness of stamping lubricants was evaluated by using the deep drawing and ironing tests. Various stamping lubricants were tested in forming of DP590 GA round cup samples. In these tests, the performance of lubricants was ranked via evaluation criteria that include punch force and the geometry of tested specimens. Deep drawing tests were conducted at two different blank holder forces, BHF (30 and 70 ton) at a constant ram speed (70 mm/s). The ironing tests were conducted to evaluate the performance of lubricants at higher tool–workpiece interface pressure than that is present in deep drawing. Polymer-based thin film lubricants with pressure additives (e.g. Lubricants A and B) were more effective than other lubricants as shown by the force (e.g. maximum punch force and applicable BHF without cup fracture) and geometry indicators (e.g. draw-in length, flange perimeter and sidewall thinning).The pressure and temperature distributions at the die–sheet interface were predicted by FE simulation of deep drawing and ironing tests. As expected, the value of interface pressure and temperature were maximum at the die corner radius.     

液体介质传热渐进温成形研究

由于液体介质的存在,在以导热油直接作为传热介质加热板料实现板料温热渐进成形中,成形初始的预胀以及成形过程中存在的背压是区别于其他渐进成形方法的显著特征。在数控渐进机床上,首先以2A12铝合金板料对成形过程中液体压力产生的板料预胀和过程背压的影响进行了研究,然后采用SUS304不锈钢板料对成形过程中的导热油温度影响进行了研究。研究结果表明：液体介质较小的压力产生的预胀和背压对成形过程没有显著影响,成形过程中为了保证导热油和板料充分接触,导热油可以保持一定的系统压力;采用液体介质直接作为传热介质加热板料进行板料温渐进成形是可行的;温度对SUS304不锈钢板渐进成形性能影响显著。     

Effects of temperature and blank holding force on biaxial forming behavior of aluminum sheet alloys

Biaxial forming behavior is investigated for three aluminum sheet alloys (Al 5182 containing 1% Mn (5182+Mn), Al 5754, and 6111-T4) using a heated die and punch in the warm forming temperature range of 200–350 °C. It is found that, while all three alloys exhibit significant improvement in their formability compared with that at room temperature, the non-heat-treatable alloys 5182 + Mn and 5754 give higher part depths than that of heat-treatable 6111-T4. The formability generally increases with decreasing BHP (BHP), but increasing the forming temperature and/or BHP minimizes the wrinkling tendency and improves the forming performance. The stretchability of the sheet alloys increase with increasing temperature and increasing BHP. For the alloys and forming conditions involved in the current study, the formability, measured in terms of part depth, comes mainly from the drawing of metal into the die cavity, although stretching effects do influence the overall forming behavior. The optimum formability is achieved by setting the die temperature 50 °C higher than the punch temperature to enhance the drawing component. Setting the die temperature higher than the punch temperature also improves the strain distribution in a part in such a manner that postpones necking and fracture by altering the location of greatest thinning.     

5182铝合金板温冲压变形的组织演变

采用温冲压试验,结合光学显微镜(OM)与透射电子显微镜(TEM),研究了汽车用5182铝合金板在不同冲压条件下的微观组织演变规律。结果表明:冲压速度为0.1 mm/s时,随着变形温度的升高,合金组织由动态回复向动态再结晶演变;变形温度为523 K时,随着冲压速度的减小,合金组织由动态回复向动态再结晶演变;变形温度的升高、冲压速度的降低有利于动态再结晶的发生。     

A study on the analytical modeling for warm hydro-mechanical deep drawing of lightweight materials

The warm hydroforming process has become an emerging technology in recent years to reduce the weight of automotive body structure and minimize the number of process steps. In this study, analytical models were developed to investigate the effects of process conditions such as temperature, hydraulic pressure, blank holder force and forming speed. The analytical model under hydro-mechanical deep drawing (HMD) condition was developed based on experimental results in the literatures. FE models were also developed to validate the analytic models. Then, the analytic model was validated through comparisons with both existing experimental results and FE results. The analytical model provided rapid and reasonably accurate results for the design of warm hydroforming process. Based on this analytic model, several parametric studies were performed regarding to the temperature, hydraulic pressure, blank holder force, and punch speed conditions. It was demonstrated that the process windows for a successful part forming could be rapidly predicted with a reasonable accuracy by the analytic model compared to lengthy and costly thermo-mechanical FEA or experimental trial and error.     

铝合金板材温热成形性能

在20℃～300℃的温度范围内,分别对7B04-T6和6061-T6铝合金薄板进行了单拉试验,结果表明,7B04-T6高强度铝合金的断后延伸率和拉伸极限应变在温热状态下都有显著的提高,比较适合于温热成形,而6061-T6则不太适合。另外,基于Fields&Backofen本构方程,对7B04-T6在不同温度状态下的强化规律进行了分析和探讨,结果表明,随着温度的逐渐升高,应变强化指数n值不断减小,应变率敏感系数m值则显著增大,应变率强化明显增强,这也是在温热状态下其成形性能提高的主要原因。