共查询到19条相似文献,搜索用时 281 毫秒
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《机械工程与自动化》2016,(6)
针对某铝合金复杂蒙皮零件的特点,在已知不同热处理状态下材料性能的基础上,对零件的拉形工艺过程进行了模拟和优化,并确定了最终拉形工艺方案,后续回弹补偿即在此基础上进行。研究了此蒙皮零件成形后的卸载回弹现象,并在PAM-STAMP软件中实现了模具型面的自动回弹补偿,通过三次模具型面补偿满足了零件的贴模度要求,并输出了经补偿后的模具CAD模型。 相似文献
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拉伸成形是飞机钣金的基本成形方法。由于飞机蒙皮种类繁琐、生产批量小,在拉形的过程中需要频繁的更换模具,而现有国内蒙皮拉形机换模仍为传统换模方式,换模时间长,换模过程繁琐。针对这一情况,研发出了一套蒙皮拉形机快速换模系统,能从根本上提高蒙皮拉形机的换模效率,进而提高蒙皮拉形机的生产效率。采用有限元方法,对所提出的蒙皮拉形机快速换模系统进行力学安全性分析,研究了该系统内部重要零部件在极限工况下的应力分布,对整个换模系统的完善与再优化具有重要的意义。分析结果显示:该蒙皮拉形机快速换系统是结构安全的。 相似文献
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双曲度飞机蒙皮拉伸成形轨迹优化与验证 总被引:1,自引:0,他引:1
加载轨迹是决定飞机蒙皮拉伸成形质量的关键因素。对某双曲度蒙皮最大截面采用应变控制的方法,解析分析并推导出拉伸成形加载轨迹范围,并作为初始加载轨迹进行优化;采用最优化理论与算法和有限元数值模拟相结合的优化方法,以减小卸载回弹、提高贴模度为研究目标,以单元最大,主应变和厚度减薄率为约束条件,建立最优化数学模型,得到合理的拉伸成形加载轨迹;在自行研制的拉伸成形试验平台上进行优化结果验证,试验结果表明,成形零件贴模度、应变分布与厚度的均匀程度均有明显提高。 相似文献
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针对可重构柔性多点模具蒙皮数字化拉形中的钉柱高度计算和工艺设计问题,开发了可重构柔性多点模具蒙皮拉形工艺设计系统.给出了系统的功能模块和体系结构,研究了曲面空间定位、模面补充、钉柱调形高度计算、毛料尺寸及拉形轨迹计算等关键技术和相关算法.在CATIA环境下,采用组件应用架构二次开发技术,实现了系统的开发.通过对实际蒙皮零件的分析和计算,验证了系统的实用性和有效性. 相似文献
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《计算机集成制造系统》2015,(6)
为准确计算贴模度,考虑回弹变形对模型对齐的影响,提出一种基于约束层次化策略的贴模度计算方法。利用数字化模型统计分析回弹量,得到回弹阈值,剔除回弹变形点。通过约束优化实现了钣金件和模具模型的对齐,并基于该对齐结果进行了贴模度计算和回弹分析。贴模度不满足要求时,施加一定的载荷仿真装配应力,计算钣金件局部发生弹性变形后的贴模度。通过对U型仿真模型和飞机翼肋钣金件实测模型的实验,验证了所提贴模度计算方法的有效性和实用性。 相似文献
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《计算机集成制造系统》2015,(6)
为减少冲压回弹导致的模具型面补偿的次数,在一步法模面几何修正的基础上,提出了反求因子补偿法:通过逆向工程技术获得试模冲压件的数字模型,将该模型当作假想的理论模型进行成形、回弹模拟,计算出仿真回弹量;由试模模面和试模件取差值获得真实补偿量,进而计算出补偿因子。假定在冲压件小变形、仿真参数、冲压工艺不变的情况下补偿因子基本保持不变,对实际设计零件做回弹仿真,再引入该补偿因子,计算出模具补偿型面。实验结果表明,该方法通过一次模面补偿,可有效控制回弹,提高补偿效率。 相似文献
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Chuang Liu Hongbing Wu Yimei Yang Junbiao Wang 《The International Journal of Advanced Manufacturing Technology》2017,91(9-12):3121-3134
Adjusting the part shape with complex flanges to compensate springback deformation is key to forming shape design for manufacturing rapidly and precisely. Classical forming shape design by displacement adjustment (DA) method using finite element (FE) simulation is usually time-consuming and not accurate enough for complex surface part in industrial application. In this paper, the forming shape is modeled by changing the relations of geometric features of part model with the new flange control surfaces directly. Control surface processing (CSP) method is presented including control surface trimming, cross section division, springback compensation, and extending to design forming shape model of doubly curved flange part with joggles rapidly. The algorithms of cross section curves division of control surfaces and subsequent subdivision of each curve with circular arc and line segments are proposed. A case-based reasoning (CBR) technique and gray relation analysis (GRA) are used to support the intelligent springback prediction of each bending segment of the cross section curve. The geometric data of control surface is expressed in XML format to realize the integration of the CAD-based tools of control surface division and compensation with the Web-based springback prediction system. The approach is demonstrated on an industrial aircraft wing rib part. The forming shape model could be designed rapidly by comparison with DA method. The part shape deviations of flange angle (?0.465° ~ 0.528°) and surface position (?0.3 mm ~ 0.3 mm) were detected by comparing the desired geometry with the actual digital formed part shape, and the results indicate that the approach can achieve the industrial part manufacturing rapidly and precisely. 相似文献
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Jun Chen Dongkai Xu Guodong Xia Xifeng Li Jieshi Chen Jian Zhang Wei Yan Yue Li 《The International Journal of Advanced Manufacturing Technology》2013,66(9-12):1449-1456
Targeting to improve dimensional accuracy of automotive body panels, elastic deformation of stamping die structure and blank thinning are considered for compensation on the die surfaces. The thinning distribution on the deformed blank is extracted from stamping process simulation results and converted into first quantitative compensation. The boundary load required for die structural FEM analysis can be automatically mapped from process simulation results by using an updated load mapping algorithm, and the die deflection is then calculated and the deflection of die surfaces is transferred into second quantitative compensation. These two quantitative contributions are referred together for the compensation on the die surface model. The proposed methodologies have been programmed and can be integrated with LS-Dyna and HyperWorks or with Autoform and CATIA. Additionally, a software toolkit used to calculate the contacting ratio between the formed blank and die face has also been developed to automatically evaluate the effectiveness of die face compensation rather than virtually check the contacting ratio. The proposed methodologies and developed software have been verified by a case study of process and die design for an automotive panel part, showing the benefit in improving the contacting ratio. 相似文献
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Iterative methods based on finite element simulation are effective approaches to design mold shape to compensate springback in sheet metal forming. However, convergence rate of iterative methods is difficult to improve greatly. To increase the springback compensate speed of designing age forming mold, process of calculating springback for a certain mold with finite element method is analyzed. Springback compensation is abstracted as finding a solution for a set of nonlinear functions and a springback compensation algorithm is presented on the basis of quasi Newton method. The accuracy of algorithm is verified by developing an ABAQUS secondary development program with MATLAB. Three rectangular integrated panels of dimensions 710 mmx750 mm integrated panels with intersected ribs of 10 mm are selected to perform case studies. The algorithm is used to compute mold contours for the panels with cylinder, sphere and saddle contours respectively and it takes 57%, 22% and 33% iterations as compared to that of displacement adjustment (DA) method. At the end of iterations, maximum deviations on the three panels are 0.618 4 mm, 0.624 1 mm and 0.342 0 mm that are smaller than the deviations determined by DA method (0.740 8 mm, 0.740 8 mm and 0.713 7 mm respectively). In following experimental verification, mold contour for another integrated panel with 400 ram~380 mm size is designed by the algorithm. Then the panel is age formed in an autoclave and measured by a three dimensional digital measurement devise. Deviation between measuring results and the panel's design contour is less than 1 mm. Finally, the iterations with different mesh sizes (40 mm, 35 mm, 30 mm, 25 mm, 20 mm) in finite element models are compared and found no considerable difference. Another possible compensation method, Broyden-Fletcher-Shanmo method, is also presented based on the solving nonlinear fimctions idea. The Broyden-Fletcher-Shanmo method is employed to compute mold contour for the second panel. It only takes 50% iterations compared to that of DA. The proposed method can serve a faster mold contour compensation method for sheet metal forming. 相似文献
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球头铣刀刀具磨损建模与误差补偿 总被引:3,自引:0,他引:3
针对刀具磨损度量方式和模型建立的问题,以球头刀具为研究对象,提出球头铣刀刀具磨损的度量方式,建立球头刀具磨损模型.以复映磨损在硬度较软加工材料上的方式测量球头刀具磨损,确定刀具磨损模型系数,给出刀具磨损模型系数确定的具体实现方法.加工试验验证球头刀具磨损度量方式的合理性和所建立刀具磨损模型的正确性,同时针对数控铣削加工中球头铣刀刀具磨损引起的误差提出离线仿真误差补偿算法,给出离线仿真误差补偿算法的具体实现步骤,通过建立的刀具磨损引起的加工误差模型仿真获得加工走刀步的误差.对于误差超差的走刀步,预先修改数控加工(Numerical control,NC)程序,保证实际加工零件满足精度要求.误差补偿验证试验表明所提出的离线仿真误差补偿算法的正确性和有效性. 相似文献
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Numerical simulation on the local stress and local deformation in multi-point stretch forming process 总被引:1,自引:1,他引:0
Shaohui Wang Zhongyi Cai Mingzhe Li Yingwu Lan 《The International Journal of Advanced Manufacturing Technology》2012,60(9-12):901-911
Multi-point stretch forming (MPSF) is a new flexible forming technique to form aircraft outer skin parts. The multi-point stretching die (MPSD) replaces the traditional fixed shape stretching die, and the sheet metal is formed over a MPSD composed by the punch element. The MPSD is a discontinuous surface of discrete stretching die, and the stress concentration and local strain occur on formed parts. These lead to generate dimples on the surface of formed part. In this paper, a series of numerical simulations on MPSF processes for stretching parabolic cylindrical, spherical, and saddle-shaped parts were carried out. The local stress and local strain in thickness distribution of MPSF part were analyzed by dispersed the blank into solid elements. The forming results of MPSF were compared with those that use traditional stretch forming, and the influences of thickness of elastic cushion and the size of punch element on the stress concentration and local strain were surveyed. The simulation results show the distribution of local stress and local deformation in different layers, and the elastic cushion and the small size of punch element can reduce the stress concentration and local deformation. The results may understand the stress distribution on the sheet and prevent the defect of dimple. 相似文献