共查询到18条相似文献,搜索用时 187 毫秒
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应用有限元软件ABAQUS对圆管绕弯成形过程进行数值模拟,研究了相对弯曲半径R/D、摩擦条件及弯曲角度对弯管壁厚变化的影响规律.研究结果表明:随着R/D值的增加,弯曲外侧最大壁厚减薄率和弯曲内侧最大壁厚增厚率都呈下降趋势;随着摩擦系数的增大,管弯曲外侧壁厚变薄率、弯曲内侧壁厚增厚率都迅速增大;弯曲角度越大,壁厚减薄率和增厚率也越大.实验验证表明,模拟结果与实验结果基本一致. 相似文献
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薄壁管材的小弯曲半径数控弯曲成形十分困难,外侧壁厚减薄是弯管成形中的加工缺陷之一,对于钛合金薄壁管尤为严重。采用模拟与实验相结合的方法,对规格为58 mm×1.5 mm的CT20钛合金管材数控弯曲成形过程中弯曲段的壁厚减薄进行了研究,得到相对弯曲半径对壁厚减薄的影响规律。结果表明,CT20钛合金管材冷弯成形时的极限相对弯曲半径(R/D)为2。 相似文献
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管材弯曲中外侧壁厚变化的数值模拟 总被引:1,自引:1,他引:0
回转牵引式弯曲成形是一种高质量、高效率的管材弯曲成形方式,能够有效地防止起皱、管壁的过分减薄和截面的椭圆化等成形缺陷.以圆形钢管为研究对象,采用有限元软件DEFORM-3D对弯曲成形过程进行数值模拟,找出管壁最大减薄处所在的位置,并获得滚珠与管壁的间隙、滚珠角速度及压力模速度对弯管外侧壁厚变化的影响规律.结果表明,随着滚珠与管壁间隙的增大,管壁受滚珠的影响变小,即壁厚变化较小;随着滚珠角速度的增大,壁厚变化先减小后增大,当滚珠角速度与弯曲模角速度大小相同时,壁厚变化最小;随着压力模速度的增大,壁厚变化渐渐变小,当压力模速度为64.28 mm·s-1时,壁厚变化最小.采用数值模拟后的优化参数在弯管机上进行试制,生产出合格件,模拟结果与实验结果基本吻合. 相似文献
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TA2钛环形管热推成形的三维有限元数值模拟 总被引:1,自引:0,他引:1
应用商业有限元软件ANSYS对TA2钛环形管热推弯曲成形过程进行了有限元数值模拟。并对成形过程中环形管内侧凹边、外侧凸边及侧面的应力、应变分布数据以及弯曲成形过程中壁厚的变化进行了分析。结果表明:管件峦变形过程中等效应力值总的变化随着弯曲角度的的增大而增大,而且弯曲管件的内侧凹边管壁的应力值比外侧凸边管壁要大,内壁受到压应力而外壁受到的拉应力;等效应力变数值内侧管壁的应变值比外侧管理壁要大,在弯曲过程中由于弯曲半径小,弯曲变形大,在弯制过程中,弯管内侧凹边受压缩使壁厚墙厚,而外侧凸边因受拉伸而壁厚减薄。数值模拟与实验所得结果一致。 相似文献
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管材剪切弯曲能够实现普通冷弯方法不能达到的超小半径弯曲,是一项较为可行的技术。针对管材剪切弯曲成形的受力与变形特点,应用塑性有限元方法研究了剪切弯曲主要工艺参数对成形后管材壁厚变化及截面椭圆度的影响,分析了变形区不同位置椭圆度及壁厚的减薄情况。研究表明:t/D越大,壁厚减薄及截面椭圆度越大;而随着R/D的增大,截面椭圆度有减小的趋势,但壁厚减薄不明显。 相似文献
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《塑性工程学报》2020,(1):27-37
基于ABAQUS有限元分析软件,首先计算和分析了在变弹性模量和常弹性模量条件下的21-6-9高强不锈钢管绕弯成形过程,并将两种情况下的模拟结果与实验结果进行对比验证,发现采用变弹性模量可使截面畸变率和壁厚减薄率的预测精度分别提高31. 8%和11. 8%。然后在变弹性模量条件下研究了几何参数对管材绕弯成形截面畸变和壁厚减薄的影响。结果表明,当弯曲角不大于45°时,截面畸变率曲线和壁厚减薄率曲线均呈抛物线状;当弯曲角大于45°时,截面畸变率从弯曲平面到初始弯曲平面的分布呈先快速增加,后缓慢减小,再缓慢增加,最后急剧减小的特征;壁厚减薄率从弯曲平面到初始弯曲平面的分布呈先急剧增加,后趋于稳定,最后急剧减小的特征。截面畸变率和壁厚减薄率随相对弯曲半径的减小而增加,相对弯曲半径以不小于2. 0为宜;截面畸变率随管材壁厚的减小,直径的增加或直径和壁厚的等比例增加而增加;壁厚减薄率随管材壁厚的增加先增加后减小,随管材直径的增加或直径和壁厚的等比例增加而减小。 相似文献
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薄壁铝合金管小弯曲半径数控弯曲是个多因素耦合、多模具约束下的复杂过程。提出以有限元模拟为基础,基于显著性的工艺参数优化方法,即采用析因因子设计分析工艺参数对成形质量,即最大壁厚减薄率和最大截面畸变变化率影响的显著性,获得影响显著的参数,即管与防皱模间间隙的最优值,并确定其他影响不显著的参数值,包括管与模具间的间隙和摩擦、芯棒伸出量和助推速度。结果应用于规格为d50mm×1mm×75mm和d70mm×1.5mm×105mm(管外径D0×管壁厚t0×弯曲半径R)的铝合金管弯曲,获得了合格的管件。 相似文献
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Numerical control(NC) bending experiments with different process parameters were carried out for 5052O aluminum alloy tubes with outer diameter of 70 mm, wall thickness of 1.5 mm, and centerline bending radius of 105 mm. And the effects of process parameters on tube wall thinning and cross section distortion were investigated. Meanwhile, acceptable bending of the 5052O aluminum tubes was accomplished based on the above experiments. The results show that the effects of process parameters on bending process for large diameter thin-walled aluminum alloy tubes are similar to those for small diameter thin-walled tubes, but the forming quality of the large diameter thin-walled aluminum alloy tubes is much more sensitive to the process parameters and thus it is more difficult to form. 相似文献
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助推作用对大口径铝合金薄壁管数控弯曲壁厚减薄和回弹的影响 总被引:2,自引:0,他引:2
以有限元软件Dynaform为平台,建立了大口径薄壁管数控弯曲及回弹的有限元模型,分析了压块助推速度和压块与管子之间的摩擦系数对壁厚减薄和回弹角的影响规律。结果表明,压块与管子之间没有摩擦或者压块的助推速度为0.9、助推速度为1.0且压块和管子间摩擦系数为0.1的条件下,管子壁厚减薄超过航空标准中允许的最大减薄量0.4375mm。在压块的助推速度不变的条件下,压块与管子之间摩擦系数从0.1增加到0.3,能够有效地降低管外侧的壁厚减薄,但是回弹角也会明显增大。当压块与管子之间的摩擦系数为定值时,助推速度从1.0增加到1.2,对管外侧壁厚减薄的改善作用不大,回弹角没有明显变化。 相似文献
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针对变压器散热管实际冲压弯曲成形表面易产生皱褶等质量不高的缺陷,通过对实际加工工艺过程的分析,找出产生成形缺陷的原因并提出有效的解决办法.应用先进的有限元板料冲压分析软件Dynaform,运用动力显示求解方法,对变压器散热管冲弯成形过程进行数值模拟分析研究,通过管料两种不同截面形状方案的模拟结果的成形极限图和厚度分布云图对比分析,表明曲线过渡光滑的截面冲弯时表面成形质量高并且不易产生褶皱,验证了通过改进模具提高变压器散热管冲弯成形表面质量办法的有效性. 相似文献
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Li Heng Yang He Zhan Mei Sun Zhichao Gu Ruijie 《International Journal of Machine Tools and Manufacture》2007,47(7-8):1164-1175
The thin-walled tube NC bending process is a much complex physical process with multi-factors coupling interactive effects. The mandrel is the key to improve bending limit and to achieve high quality. In this study, one analytical model of the mandrel (including mandrel shank and balls) has been established and some reference formulas have been deduced in order to select the mandrel parameters preliminarily, i.e. mandrel diameter d, mandrel extension e, number of balls n, thickness of balls k, space length between balls p and nose radius r. The experiment has been carried out to verify the analytical model. Based on the above analysis, a 3D elastic–plastic FEM model of the NC bending process is established using the dynamic explicit FEM code ABAQUS/Explicit. Thus, the influences of mandrel on stress distribution during the bending process have been investigated, and then the role of the mandrel in the NC precision bending process such as wrinkling prevention has been revealed. The results show the following: (1) Wrinkling in the tube NC bending process is conditional on membrane biaxial compressive stress state; the smaller the difference between the biaxial membrane stresses is, the more possibility of wrinkling occurs. (2) If the mandrels of larger sizes are used, it will cause the neutral axial to move outward and the difference between the in-plane compressive stresses to become more obvious, which may increase minimum wrinkling energy and anti-wrinkling ability. But the larger mandrel sizes make outside tube over-thinning. (3) When the mandrel extension length increases, the neutral axial will move outward and the difference between the biaxial compressive stresses becomes larger, but the significance is less than that of the mandrel diameter. The excessive extension will cause tube to over thin or even crack. (4) The significance of ball number's effect on the neutral axial position and difference between biaxial compressive stresses is between ones of mandrel diameter and mandrel extension. Increasing the ball number will enhance the thinning degree and manufacturing cost. The results may help to better understanding of mandrel role on the improvement of forming limit and forming quality in the process. 相似文献