共查询到20条相似文献,搜索用时 46 毫秒
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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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G.Y. Zhao Y.L. Liu C.S. Dong H. Yang X.G. Fan 《Journal of Materials Processing Technology》2010,210(9):1224-1231
The rotary-draw bending process for thin-walled rectangular tube of aluminum alloy may produce a wrinkling phenomenon if processing parameters are inappropriate, especially for tubes with thin wall and small bending radius. To predict this wrinkling rule rapidly and accurately, here, a wrinkling wave function was proposed and a wrinkling prediction model was developed based on the deformation theory of plasticity combined with the energy method, and then the minimum bending radius without the occurrence of wrinkling in the process was obtained. Furthermore, the effects of geometrical parameters and the material properties of the tube on the minimum bending radius were analyzed. The results show that larger thickness-to-width ratio (t/b) and thickness-to-height ratio (t/h) are beneficial to improve the wrinkling limit of the tube. The minimum bending radius becomes smaller with an increase in strain-hardening exponent of the tube, whereas with the strength coefficient decreasing. And the Young's modulus has little effect on the wrinkling limit. These achievements are helpful to develop the bending technique and provide a guideline in rotary-draw bending process for thin-walled rectangular aluminum alloy tube. 相似文献
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Qingqing Zhang Ding Tang Dayong Li Yinghong Peng 《Journal of Materials Processing Technology》2010,210(14):1876-1884
Microchannel aluminum flat tubes have attracted more and more attention in recent years, especially in ACR (air conditioning and refrigeration) industry. Rotary-draw bending is a versatile and precise method in forming of tubes. Compared with traditional out-of-plane bending method, in-plane bending can cause different forming defects. During the process, wall thinning, sectional distortion, wrinkling, and channel shape degradation are the main defects that affect tube quality in industrial applications. In this paper, an experimental apparatus for flat tube in-plane bending is manufactured, and experiments are performed to examine the forming quality of tubes. Considering the characteristics of the bending process, based on the LS-DYNA software environment, a 3D elastic–plastic finite element model is established and validated by experiment. Using the validated FE model, the forming quality of microchannel flat tube bending process is evaluated quantitively. Furthermore, the influence mechanism of process parameters, such as bending radius, tool–tube clearance, and channel diameter, has been revealed. The results indicate that the degradation of the tube channels is relatively small under common process conditions; bending radius is the main factor which influences the forming quality of the flat tube; the tool–tube clearance mainly affects the wrinkling of the flat tubes; channel diameter has little effect on the formability of tube. 相似文献
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2099-T83铝锂合金2形型材是大型客机C919中后机身重要桁架零件,四轴滚弯成形是加工此类零件的主要方法。由于铝锂合金比强度大,同时2形型材结构的非对称,相比于普通铝合金型材,铝锂合金2形型材滚弯成形中极易产生斜弯曲。为此,利用有限元软件ABAQUS对2形型材的四轴滚弯过程进行了模拟,分别研究了滚轮间隙、下滚轮与型材之间竖直方向预留间隙、左右滚轮X方向移动量对2形型材四轴滚弯中斜弯曲的影响,确定了最佳滚弯工艺参数。基于最佳滚弯工艺参数进行了滚弯工艺试验。结果表明,采用滚轮间隙0.2 mm、下滚轮与型材之间竖直方向预留间隙0.3 mm、左右滚轮X正方向移动量1.5 mm时能有效解决2形型材滚弯的斜弯曲问题。 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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斜辊矫直作为管材生产的最后一道工序,为达到薄壁细管严苛的精度要求,最优矫直工艺参数的设定至关重要。为解决薄壁细管矫直的难点,以现有的十辊矫直机为基础,设计了十辊薄壁细管矫直的模型,并进行了工艺参数研究。利用有限元软件ABAQUS建立了薄壁细管材矫直的有限元模型,通过分析不同条件下矫直后管材的X、Y方向的直线偏差、径向偏差得出了适合薄壁细管的最佳压弯量及压扁量,以此拟合出公式。根据公式计算了两组不同情况下管材的工艺参数,通过仿真模拟及实验验证了公式的可靠性,为薄壁细管精密矫直机的开发制造提供了理论依据。 相似文献
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《Journal of Materials Processing Technology》2014,214(2):311-317
A traditional rotary draw bending die on the numerically controlled (NC) tube benders or other benders can bend tubes with only one kind of outer diameter. It is difficult for such a situation to meet the requirement of modern manufacturing with characters of much varieties and small batch. The present study proposed a new concept of rotary draw bending die called MDB-Die (Multiple-diameter Bending Die), on which tubes with different outer diameters within a definite range can be bent using the same die by only adjusting the pads inside the die set. Numerical and experimental approaches were employed to investigate the forming process of tubes with different outer diameters when bent on the MDB-Die, especially on the characters of force and elastic-plastic deformation of tube wall, and the effects of groove shapes and bending parameters on the cross-section distortion and wall thinning in the process. Analytical expressions in simple tube bending based on plastic theories given by Tang (2000) for calculating the magnitude of stresses, together with the wall thickness change, deviation of the neutral axis, and section flattening, were also used for comparison. The result proved that tubes with different outer diameters (from 18 to 25 mm in the study) can be bent successfully on MDB-Die without degrading the bending quality, i.e., the aspect ratios of section distortion of less than 5% and wall thinning of less than 7.8%. 相似文献
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薄壁管数控弯曲截面畸变的实验研究 总被引:5,自引:1,他引:5
截面畸变是薄壁管小弯曲半径数控弯曲成形容易出现的成形缺陷之一。文章采用实验法,研究了芯头个数、芯棒伸出量、弯曲角度、压块润滑状态、相对弯曲半径、材料等因素对截面畸变的影响;并提出了减小截面畸变的有效措施。结果表明,增加芯头个数与芯棒伸长量都能减小弯管的截面畸变,但两者都导致弯管壁厚减薄量增大;随着弯曲角度的增加,截面畸变越严重,相对弯曲半径越小,无芯棒与芯头支撑段弯管的截面畸变愈严重;在压块无润滑情况下,弯管的截面畸变和壁厚减薄量都小,并且在同等弯曲条件下,1Cr18Ni9Ti弯管的截面畸变小于LF2M弯管。 相似文献
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薄壁管小弯曲半径数控绕弯成形芯模效用的实验研究 总被引:2,自引:1,他引:2
薄壁管数控弯曲中带芯头的柔性芯模是提高薄壁管件成形极限和成形精度的关键因素。文章建立了绕弯过程芯模(包括芯棒和芯头)的理论解析模型,包括了芯模直径d、芯棒伸出量e、芯头个数n、芯头厚度k、芯棒/芯头孔心间距p及芯棒圆角半径r等参数的选取公式的推导,获得了不同弯曲规格下的芯模参数取值范围,验证了解析模型的合理性;实验研究了芯模参数对管材失稳起皱、壁厚减薄和截面畸变的影响规律。通过分段抽芯的工艺方法,完成了38mm×1mm×38mm(1D)高难度不锈钢管件的弯曲。 相似文献
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为了发展大直径薄壁纯钛管数控加热弯曲技术,实验研究了大口径薄壁CP-3管材在不同温度下数控弯曲后的内外侧塑性变形机制。通过EBSD分析和维氏显微硬度测试方法,对数控弯曲温度293、423和573 K下弯管件试样弯曲外侧受拉区域以及弯曲内侧受压区域进行显微组织变化和维氏硬度分析。结果表明:1)在不同温度下数控弯曲变形后,弯管外侧塑性变形机制主要为滑移,孪生变形微弱,择优取向类似于初始管材的;弯管内侧塑性变形机制主要以{1 012}孪晶为主,滑移为辅助机制,且孪晶使管壁材料择优取向产生剧烈转变。2)维氏硬度的变化与塑性变形机制及织构有关。弯曲变形后,管材试样内外侧轴向与周向的维氏硬度值均显著得到提高,且管材试样内侧的维氏硬度值要明显高于外侧的,周向的维氏硬度值高于轴向的。 相似文献
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应用ABAQUS/Explicit软件平台建立了大直径薄壁铝合金封头剪切旋压成形过程的有限元数值模型,通过数值模拟对大直径薄壁铝合金封头在剪切旋压过程中的应力应变分布进行了分析,获得了工艺参数对成形质量的影响规律为:随旋轮圆角半径R、旋轮进给比f及芯模转速n的增大,旋压件的不均匀变形度呈增大趋势;随旋轮圆角半径、旋轮进给比的增大,旋压件壁厚极小值逐渐减小;随芯模转速提高,壁厚极小值增大,旋压件壁厚极大值对工艺参数的变化不敏感。在此基础上确定了优化工艺参数为:R=12 mm,f=1 mm·r~(-1),n=40 r·min~(-1),并进行剪切旋压成形试验,获得了质量合格的Ф2600 mm大直径薄壁铝合金封头样件。 相似文献
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高温合金旋压塑性变形稳定性试验研究 总被引:1,自引:0,他引:1
通过高温合金管材不同旋压变薄率的试验,探讨了常用高温合金的旋压工艺参数。在高温合金管材可旋性试验的基础上,有效控制塑性变形的稳定流动,可以旋压高精度薄壁管材。当坯料退火以后,经旋压工艺参数优化,可提高变形区金属三向塑性流动的稳定性,并有助于获取尺寸精良的管材。 相似文献
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Chunfeng Li Dahai Liu Haiping Yu Zhengbo Ji 《International Journal of Machine Tools and Manufacture》2009,49(2):117-124
In order to establish the efficacy of electromagnetically assisted sheet metal stamping (EMAS), the formability of 5052 aluminum alloy sheet in a quasi-static–dynamic tensile process is experimentally investigated using a combined quasi-static tension and the pulsed electromagnetic forming (EMF) method. Data on the formability of aluminum alloy 5052-O employing this combined loading method is compared with data for traditional quasi-static tensile tests. Results show that the formability of aluminum alloy sheet undergoing a quasi-static–dynamic tensile process is dramatically increased beyond that exhibited in quasi-static tensile tests, and a little higher than or at least similar with that obtained in the fully dynamic EMF process. The forming limits of aluminum samples with both low and high pre-strain levels are almost similar in quasi-static–dynamic tensile process, which makes it possible stretching the sheet to a higher quasi-static pre-strain level without weakening its total quasi-static–dynamic formability. This would enable the use of a quasi-static pre-form fairly close to the quasi-static material limits for design of an EMAS process in manufacturing large aluminum alloy shell parts. 相似文献