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合理的壁板展开板坯不但可以节省材料、减少甚至免去后续的修边工艺,大大降低生产成本,而且能改善成形条件,提高成形质量。然而,喷丸成形过程中塑性变形的不可逆性,导致整体壁板展开计算在理论上无精确解。同时,由于塑性变形与路径相关,且壁板局部特征存在差异,喷丸成形过程中整体壁板变形不均匀、随机性大。因此,整体壁板板坯展开工艺,无论在理论方法上还是在技术应用上,均成为了整体壁板制造的难点。 相似文献
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《载人航天》2017,(5)
针对某大型空间航天器带法兰异构壁板薄厚不一致、刚度不均匀、在成形过程中容易产生断裂的难题,利用ABAQUS对整体壁板压弯成形过程进行了有限元分析,讨论了直接压弯成形过程中易产生缺陷的部位和原因。结果表明,壁板直接压弯成形加强筋及其交汇处应力集中,应力值最大,为成形过程的薄弱区,容易产生失稳及断裂。针对该情况,提出了柔性补强压弯成形工艺方法,并进行了成形工艺实验验证,实验结果表明,采用该方法成形的壁板蒙皮与加强筋表面质量良好,曲率均匀,无缺陷,满足尺寸精度要求;最后,在有限元模拟及工艺验证实验的基础上,利用柔性补强技术和分段压弯成形技术相结合的方法,解决了带法兰异构壁板传统成形法兰过渡处易断裂的成形难题,实现了该大型空间航天器多种带法兰异构壁板的成形制造。 相似文献
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大型铝合金整体壁板压弯成形工艺研究 总被引:1,自引:0,他引:1
本文利用ABAQUS有限元分析软件,基于Mises屈服准则和动态显式算法模拟了铝合金整体壁板压弯成形过程,研究了压弯成形过程中铝合金整体壁板的应力应变状态,分析了整体壁板压弯成形中易产生缺陷的部位及原因.为避免缺陷产生,提出了聚氨酯橡胶填块压弯成形工艺方法,并进行了成形实验研究. 相似文献
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大型机翼整体壁板时效成形技术 总被引:5,自引:0,他引:5
分析了单级时效、双/多级时效、振动时效以及应力位向效应等工艺措施和因素对铝合金机翼整体壁板材料时效成形特性的影响,得到以下结论:应采用双/多级时效处理,以提高成形后壁板材料的综合性能;应采用振动时效应力松弛,以加速应力松弛,降低回弹,并提高成形后壁板材料的抗疲劳性能;对时效过程中存在应力位向效应的铝合金,应设计合适的时间温度曲线与加载曲线,以避免壁板材料因应力位向效应产生各向异性,导致材料屈服强度降低。提出了大型机翼整体壁板时效成形的工艺流程,给出了成形过程中热压罐内的温度时间曲线和气压时间曲线;提出了成形工装的模块化、标准化与柔性化设计以及解决壁板时效成形回弹问题的有限元方法,并对中国研究发展大型机翼整体壁板时效成形技术提出了建议。 相似文献
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涡轮球壳作为液体火箭发动机的关键件,影响着火箭发射的成败。而采用传统自由锻工艺生产的涡轮球壳性能一直无法满足设计要求,基于此本文提出采用模锻工艺进行涡轮球壳成形,通过对GH4061微观组织及涡轮球壳成形过程仿真模拟,系统地研究了GH4061合金最佳成形温度及临界变形量参数规律和涡轮球壳成形过程的应变分布特点。结果表明:GH4061合金最佳成形温度为1 000 ℃,最佳变形量为20%~40%。涡轮球壳采用挤压模锻工艺生产,坯料在模具中充填完整,不存在缺肉、夹杂、裂纹等缺陷,端面平正,飞边分布均匀,各尺寸及性能满足锻件要求。成形过程中变形量最小的位置在涡轮球壳下端面,晶粒尺寸ASTM 5~6级。 相似文献
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《航空制造技术》2017,(20)
激光喷丸成形技术利用激光诱导冲击效应在壁板表层引入非均匀分布塑性应变,塑性层厚度是传统机械喷丸的5~10倍,能够有效克服传统壁板成形技术的不足,实现大型高加筋复杂型面带筋壁板的形性一体化成形制造。对激光喷丸成形技术的进展,从激光喷丸成形机理与规律、复杂型面激光喷丸成形几何形状控制、大型带筋壁板激光喷丸成形系统几个方面进行了综述;回顾了激光喷丸成形的发展脉络,介绍了大型壁板激光喷丸成形技术研究与应用现状,并对近几年激光喷丸成形技术的发展与趋势进行了梳理;指出了实现大型整体壁板激光喷丸成形应用的核心是掌握变形机理,解决成形工艺规划问题,并研制适用于大型整体壁板成形的工艺装置。 相似文献
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Deformation Behavior of Medium-strength TA18 High-pressure Tubes During NC Bending with Different Bending Radii 总被引:1,自引:0,他引:1
JIANG Zhiqiang a ZHAN Mei a YANG He a * XU Xudong b LI Guangjun b a School of Materials Science Engineering State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an China b Chengdu Aircraft Industry Corporation Ltd. Chengdu China 《中国航空学报》2011,24(5):657-664
To improve the forming quality and forming limit of the numerical control (NC) bending of high-pressure titanium alloy tubes, in this study, using three-dimensional (3D) finite element method, deformation behavior of medium-strength TA18 high-pressure tubes during NC bending with different bending radii is investigated. The results show that the cross-sectional deformation and the wall thickness variation during NC bending of TA18 tubes using a small bending radius (less than 2 times of tube outside diameter) are clearly different from that using a normal bending radius (between 2 and 4 times of tube outside diameter). For bending with a normal bending radius, with or without a mandrel, the distribution of the flattening in the bending area resembles a platform and an asymmetric parabola, respectively. For bending with a small bending radius, with or without a mandrel, the flattening both distributes like a parabola, but the former has a stable peak which deflects toward the initial bending section, and the latter has a more pronounced peak with a bending angle and deflects slightly toward the bending section. The wall thickness variations with a normal bending radius, with and without a mandrel, both resemble a platform when the bending angle exceeds a certain angle. For the bending with a small radius, the distribution of the wall thickness variation without a mandrel follows an approximate parabola which increases in value as the bending angle increases. If a mandrel is used, the thickening ratio increases from the initial bending section to the bending section. 相似文献
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薄壁管数控弯曲过程中失稳起皱的主要影响因素 总被引:10,自引:0,他引:10
针对薄壁管数控弯曲精确成形过程在多因素交互作用下可能发生失稳起皱这一复杂物理问题, 基于起皱能量准则和有限元方法相结合, 提出了预测该过程起皱发生的能量( 数值) 方法, 研究了影响薄壁管数控弯曲成形过程起皱发生的主要因素及影响机制。结果表明, 弯曲半径、相对管径、芯棒伸长量和摩擦因素是影响薄壁管数控弯曲精确成形过程起皱发生的主要因素, 而材料的应力强度系数和加工速度等对起皱发生影响较小。研究结果为薄壁管数控弯曲精确成形过程参数的确定和优化创造了条件。 相似文献
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《中国航空学报》2020,33(2):721-729
3D free bending process, an advanced metal forming technology, has attracted much attention due to its unique geometrical flexibility and efficiency. Filling tubes with materials may effectively reduce the distortion in the cross-section area and restrain wrinkling and collapse of tube wall. In the present study, the impacts of filling different materials on the copper tubes during 3D free bending process were investigated. We have found that copper tubes filled with low melting point alloys could induce the most uniform stress distribution, which result in better formability and moderate thickness changing rates when compared to SS304 steel balls and PU rubbers. The lowest ellipticity reached to 1.467%. 相似文献
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《中国航空学报》2021,34(11):267-276
Three dimensional (3D) tubes, which possess the characteristics of space saving, lightweight and high strength, are widely used in many high-end industries such as aviation, aerospace, automobile and shipbuilding. However, when manufacturing a 3D tube in flexible bending process, springback is a big obstacle for improving the forming quality. In this paper, a new comprehensive strategy for springback control of 3D tubes is proposed. The strategy can be described as follows: (1) define the desired shape and manufacture shape; (2) optimize the manufacture shape using two tooling design methods (e.g. DA (displacement adjustment) method and B&T (bending and twisting) method presented in this paper); (3) make a discretization of the manufacture shape to acquire the optimized forming parameters. Additionally, experiment is implemented to validate the effectiveness of the new strategy. Results show that forming parameters acquired by the new strategy are partially effective. The new strategy also demonstrates that, during 3D tubes forming, the deviation caused by over-bent elements can be counteracted by the deficient-bent elements. This principle is helpful to reduce the difficulty of parameter determination in future. 相似文献
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液压橡皮成形是飞机制造业中的一种非常重要的方法。回弹是液压橡皮成形中常见的缺陷,并直接影响产品质量。为此探讨了回弹产生的力学机理,并利用专业金属板料成形软件PAM-STAMP2G模拟凸弯边零件橡皮成形的成形和回弹过程。仿真结果表明:应力的分布不均匀导致了回弹角度分布不均匀,下层纤维沿弯曲方向的压应力的较大值和下层纤维沿弯曲方向的压应力较小值对应于回弹角度的较大值和较小值。 相似文献
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针对目前拉弯成形中的问题,采用有限元模拟的方法,对带下陷拉弯过程进行计算机仿真,得到优化后的工艺参数,避免了盲目的试拉,提高了加工效率,降低了拉弯成本,积累了带下陷拉弯成形的经验,提高了公司拉弯工艺水平。 相似文献
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薄壁零件如汽车覆盖件、机翼、导弹壳体、燃料储箱等在汽车、航空、航天、船舶、家电、机械等行业有着广泛的应用。本文通过对某产品薄壁纯铝碗状壳渐进成型制造工艺的综合分析,阐述了在薄壁回转体零件的加工中,如何通过选择不同的制造工艺,采用“分层制造”思想,将复杂的三维数字模型沿高度方向分解成一系列等高线层,从而实现对产品的渐进塑性成型加工,希望此文对同类型的产品的制造有所借鉴。 相似文献