镁合金AZ31盒形件拉深成形有限元模拟分析

摘 要:利用有限元数值模拟分析了各工艺参数(拉深温度、凸模圆角半径及凹模内圆角半径)对镁合金AZ31盒形件拉深成形性能的影响,并通过实验进行了验证.结果表明:采用最佳拉深温度和最佳的凸模圆角半径、凹模内圆角半径可以有效地改善厚度为0.5mm的镁合金AZ31板材的拉深成形性能.     

镁铝层合板拉深成形性能的试验研究

采用正交试验设计,对镁铝层合板进行了不同成形条件下的拉深试验,研究了成形温度、凸模温度、拉深速度和凹模圆角半径对板料成形性能的影响。结果表明:在成形温度是最重要的影响因素的基础上,不同成形温度下其他条件的影响程度有所不同,凸模温度和凹模圆角半径较拉深速度更为重要;在镁合金最佳成形温度范围内,层合板极限拉深比在200℃达到最大,且高于镁合金单板极限拉深比,铝合金的包覆对于改善镁合金的成形性能有很重要的影响。     

镁合金筒形件压力润滑拉深壁厚分析

通过对室温下AZ31B板筒形件压力润滑拉深的成形过程数值模拟分析,研究了内压力、压边力和凸模圆角半径等工艺参数对成形件壁厚差的影响.通过分析比较镁合金普通拉深和压力润滑拉深的成形效果,研究了成形件的壁厚分布情况.     

AZ31B镁合金板液压-机械拉深试验研究

对AZ31B镁合金板进行液压-机械拉深试验,分析其变形特点和液压力对其成形性能的影响规律,并对液压拉深件的破裂现象进行了分析.试验结果表明,AZ31B镁合金板在液压-机械拉深时的成形性能比普通拉深时的差,主要原因是AZ31B镁合金板本身的塑性变形能力差,液压力未能及时发挥作用.     

DP590高强度板拉深成形应变路径规律研究

以某盒形件为例,以有限元分析软件Dynaform为平台,建立DP590高强度板拉深成形有限元模型,研究凸模圆角半径及摩擦系数对拉深成形应变路径的影响.结果表明:适当增大圆角尺寸可有效提高成形性能,增大摩擦系数减小材料流动,不利于高强度板的成形.     

方形盒制件圆角处拉深破裂的数值模拟

金属薄板成形的数值模拟技术在冲压件生产和模具设计中起着重要的作用。文章借助Dynaform软件对某方形盒制件拉深破裂现象进行数值模拟,分析其产生原因和影响因素,并利用正交实验找出防止该制件圆角破裂的拉深条件组合。结果表明,在冲压速度、凸模圆角半径、摩擦系数和板料厚度4个因素中,凸模圆角半径对盒形件拉深破裂的影响最大。为降低因圆角处板料剧烈减薄而产生破裂的几率,盒形件拉深时应采用较大的凸模圆角半径。     

铝合金复杂曲面薄壁件液压成形技术

介绍了适合于制造铝合金复杂曲面薄壁件的液压成形技术,包括充液拉深、可控径向加压充液拉深和液体凸模拉深。由于充液拉深能提高成形极限,适合于制造铝合金复杂型面零件。可控径向加压充液拉深通过径向压力向内推料,进一步提高了成形极限,适合于成形大高径比筒形件。液体凸模拉深适合于获得深度较大、形状复杂、尤其底部具有小过渡圆角的复杂形状零件。     

拉深筋对金属板材成形极限的影响

为了提高拉深成形数值模拟中破裂缺陷的预测精度,针对拉深成形工艺中拉深筋对金属板材成形性的影响展开了研究。设计加工了3种不同高度的凸筋镶块和3种不同肩圆角半径的凹筋镶块,将凸筋镶块与凹筋镶块组合出不同截面尺寸的拉深筋,然后并将金属板材拉过拉深筋,然后分析了过筋产生的预应变以及拉深筋的截面几何参数对板材成形极限的影响规律。结果表明,板材流过拉深筋后,板材的成形极限提高,成形极限曲线在应变空间中向上偏移。在任意一组拉深筋镶块的作用下,成形极限曲线的偏移量与过筋产生的预应变近似呈线性关系;在不同尺寸的拉深筋镶块产生相同大小的预应变时,成形极限曲线的偏移量随着拉深筋高度的增大而增大,随着肩圆角半径的增大而减小。     

镁合金方形件液压拉深成形的数值模拟

采用Dynaform有限元软件对AZ31B镁合金方形件的液压拉深过程进行数值模拟,研究了分块压边条件下,压边力加载方式、拉深速度、液压力等工艺参数对镁合金方形件壁厚差值和最小壁厚值的影响规律,并分析了方形件的壁厚分布特点.结果表明:镁合金方形件分块压边液压拉深过程中,当圆角块和直边块初始压边力分别为3和1kN,压力增幅△Q为500 N,且均采用“增-恒-减”加载方式,液压力取12 MPa,拉深速度为3000mm·s-1时,可以获得较好的成形效果;拉深后期,压边力大小不断增大或保持不变对镁合金方形件成形效果的影响程度基本一致;液压力大小对镁合金方形件的壁厚极值分布位置影响较小.     

镁合金方形件液压拉深成形的数值模拟

采用Dynaform有限元软件对AZ31B镁合金方形件的液压拉深过程进行数值模拟,研究了分块压边条件下,压边力加载方式、拉深速度、液压力等工艺参数对镁合金方形件壁厚差值和最小壁厚值的影响规律,并分析了方形件的壁厚分布特点。结果表明:镁合金方形件分块压边液压拉深过程中,当圆角块和直边块初始压边力分别为3和1kN,压力增幅ΔQ为500N,且均采用"增-恒-减"加载方式,液压力取12MPa,拉深速度为3000mm.s-1时,可以获得较好的成形效果;拉深后期,压边力大小不断增大或保持不变对镁合金方形件成形效果的影响程度基本一致;液压力大小对镁合金方形件的壁厚极值分布位置影响较小。     

Deep drawing of square cups with magnesium alloy AZ31 sheets

The square cup drawing of magnesium alloy AZ31 (aluminum 3%, zinc 1%) sheets was studied by both the experimental approach and the finite element analysis. The mechanical properties of AZ31 sheets at various forming temperatures were first obtained from the tensile tests and the forming limit tests. The test results indicate that AZ31 sheets exhibit poor formability at room temperature, but the formability could be improved significantly at elevated temperatures up to 200 °C. The test results were then employed in the finite element simulations to investigate the effects of process parameters, such as punch and die corner radii, and forming temperature, on the formability of square cup drawing with AZ31 sheets. In order to validate the finite element analysis, the deep drawing of square cups of AZ31 sheets at elevated temperatures was also performed. The experimental data show a good agreement with the simulation results, and the optimal forming temperature, punch radius and die corner radius were then determined for the square cup drawing of AZ31 sheets.     

Two-stage cold stamping of magnesium alloy cups having small corner radius

A two-stage cold stamping process for forming magnesium alloy cups having a small corner radius from commercial magnesium alloy sheets was developed. In the 1st stage, a cup having large corner radius was formed by deep drawing using a punch having large corner radius, and the corner radius of the cup was decreased by compressing the side wall in the 2nd stage. In the deep drawing of the 1st stage, fracture was prevented by decreasing the concentration of deformation with the punch having large corner radius. The magnesium alloy sheets were annealed at 500 °C to increase the cold formability. Circular and square cups having small corner radii were formed by the two-stage cold stamping. For the circular cup, the height of the cup was increased by ironing the side wall in the 1st stage. The radii of the bottom and side corners of the square cup were reduced by a rubber punch for applying pressure at these corners in the 2nd stage. It was found that comparatively shallow magnesium alloy square cups used as cases of laptop computers and mobile phones can be satisfactorily formed at room temperature without heating by the two-stage stamping.     

Development of incremental deep drawing process

This paper deals with development of an incremental deep drawing process. On a newly developed incremental deep drawing set-up, the aluminium sheets are formed; the forming is carried out by deep-drawing the blank as in the conventional method but incrementally. Fractures at the punch or die corner in the blank may or may not occur depending on the conditions; the process parameters involved are punch size, punch corner radius, increment in punch displacement, blank holding force or pressure, etc. It is thus shown that different shapes are formed by one set of common tools. It is thereby confirmed that incremental deep drawing is possible without using a particular tool set for a particular shape.     

铝锂合金的温热拉深成形性能

在数值模拟研究压边力、毛料直径、凸凹模圆角半径、变形温度等对5A90铝锂合金板材拉深成形影响的基础上,采用正交试验设计方法对拉深成形工艺参数进行优化设计,并进行相应的拉深成形试验。研究表明,变形温度对拉深成形影响最显著,其次是毛料大小的影响,而变形速度和压边力的大小对拉深成形影响较小。通过对试验结果的计算、分析和总结,获得了5A90铝锂合金板材拉深成形的最佳工艺参数组合,在最佳工艺参数条件下,铝锂合金的极限拉深系数达到了0.45。     

圆筒形件充液拉深成形精度

本文系统地研究了平底和球面圆筒形件充液拉深成形精度。充液拉深成形中，由于高压液体紧紧将毛坯贴向凸模表面，因而零件具有良好的贴模性并能获得很高的内径精度。同样，由于液压的施加在凸模圆角和压边圈之间产生与凸模运动方向相反的局部胀形，减小了凸模圆角处的弹复，提高了侧壁及球面件底部的形状冻结性。但是，平底零件的底面形状因液压的施加而使形状冻结性不好，平面度降低。     

Experimental studies of deep drawing of AZ31B magnesium alloy sheet under various thermal conditions

The effect of temperature and temperature gradient within the blank on formability of AZ31B-O magnesium alloy is investigated. The effect of blank size on the success of isothermal deep drawing is studied. As blank size increases, forming under isothermal conditions becomes more difficult. To address this issue, non-isothermal forming is investigated and a formability window is identified in which the temperature at the punch nose must lie below the flange temperature to promote enhanced drawability, but above the temperature for activation of non-basal slip systems (to avoid low temperature fracture). The effect of punch speed on the forming forces, thickness and strain distribution within the formed cup is also investigated. At higher punch speeds, small cracks initiate at the punch radius region which increases the possibility of failure. Finally, the fracture surfaces from each thermal condition are observed using scanning electron microscopy. It is demonstrated that the fracture mechanism during deep drawing of magnesium alloy AZ31B is dependent on the forming temperature which controls the active deformation mechanisms.     

高强度铝合金7075的温成形性能(英文)

对铝合金板料7075在加热状态下的成形性能进行研究。首先,通过单向拉伸试验得到不同温度以及不同应变速率下的应力—应变关系。然后,通过极限拉伸比(LDR)试验和极限拱顶高(LDH)试验对其在不同温度下的拉伸性能和胀形性能进行研究。最后,对不同温度下成形后材料的力学性能进行研究。结果表明:7075铝合金的拉伸和胀形性能在140~220°C均得到较大提升;当温度高于260°C时,由于成形温度对板料热处理状态的影响,成形性能和成形后材料的力学性能均出现下降趋势。     

Formability of AZ31 magnesium alloy sheets at warm working conditions

Fine-grained AZ31 magnesium alloy sheets were prepared through hot-rolling process. To investigate the mechanical properties of the sheets, uniaxial tensile tests were conducted at various temperatures and strain rates. The formability of AZ31 alloy sheets at warm working conditions was evaluated by limit drawing ratio (LDR) tests and limit dome height (LDH) tests at temperatures from 50 to 240 °C. It is demonstrated that LDR increases remarkably with temperatures, whilst LDH does not seem to increase much with temperatures. The maximum LDR reaches 2.65 at a punch speed of 30mm/min at 200 °C, whereas the maximum LDH is only 10.8 mm, showing good deep drawability and poor stretchability of AZ31 alloy sheets. In addition, punch speeds and punch temperatures were found to have significant effects on the deep drawability of AZ31 magnesium alloy sheets.