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为了确定更为符合实际的筒形件强力旋压工艺参数的选用原则,利用有限元软件Abaqus/Explicit准静态模块,对一次减薄成形的工艺,不同工艺参数下筒形件两旋轮反旋旋压过程进行了动态模拟、变形以及应力应变的分析.分析表明:强力旋压毛坯件的变形流动主要是轴向变形,影响成形质量的因素主要是成形过程中的径向变形和切向变形.当旋轮圆角半径r=15mm,旋轮工作角α=30°时,金属旋压件的径向变形和切向变形比较合理,既容易顺利进行旋压成形又不易引起失稳现象,为实际加工旋轮的参数选择提供了依据. 相似文献
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运用ABAQUS软件的非线性接触对筒形件旋压成形进行数值模拟.当毛坯壁厚为5 mrn时,正旋和反旋最适减薄率分别为32%和30%,一次旋压合格工件的极限减薄率分别为48%和42 %.随着毛坯壁厚的增加,极限减薄率将减小,且正旋和反旋的最适减薄率也随之减小.当毛坯壁厚达到7 mm时,旋压力的增长率将明显提高.研究表明,利用有限元数值模拟可为选定工艺技术参数、提高产品质量和减少试加工过程提供有效的途径. 相似文献
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为了研究对轮旋压成形机理,突破对轮旋压成形精度控制技术,采用有限元方法分析了道次减薄率、进给比、旋轮成形角以及内旋轮圆角半径等工艺参数对旋压件圆度、直线度及壁厚差的影响。结果显示:当道次减薄率Ψt=20%~30%、进给比f=1.5~2.0 mm·r-1、旋轮成形角αρ=25°、内旋轮圆角半径rρ内=10 mm时,旋压件成形精度最高。同时,分析了在总压下量为9 mm时,内、外旋轮在不同压下量下对成形精度的影响。结果表明:当外旋轮压下量为5 mm、内旋轮压下量为4 mm时,旋压件精度最高。最后,通过工艺实验验证了有限元仿真结果的准确性,结果显示两者偏差小于15%。 相似文献
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7055铝合金兼具钢的高强度与钛合金的低密度,同时具有良好的耐腐蚀性,且成本远低于钛合金,可推广并应用至固体火箭发动机的制造领域。通过分析毛坯性能、材料可旋性和温度对7055高强铝合金材料的力学性能的影响,制定了合理的工艺试验方案,以研究该材料旋压成形精度以及缺陷控制方法。通过开展7055高强铝合金多道次旋压试验,得到了旋压温度对成形缺陷的影响规律,以及旋轮成形角、进给比对工件成形精度的影响规律。最终确定了成形精度最佳的温度区间为90~110℃,旋轮圆角半径为6 mm,进给比为0.40~0.45,实现了7055高强铝合金筒形件壁厚由8.0 mm至1.6 mm的多道次、大减薄量的旋压成形,为该材料应用于固体火箭发动机壳体的旋压成形奠定基础。 相似文献
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V. S. Ivanova 《Metal Science and Heat Treatment》2005,47(7-8):305-311
A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing
nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling
those of biosystems.
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Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005. 相似文献
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The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product. 相似文献
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O. N. Vlasova N. N. Korneeva V. I. Eremenko O. Kh. Fatkullin N. M. Semenova S. N. Petrova D. D. Vaulin 《Metal Science and Heat Treatment》1991,33(12):924-931
Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991. 相似文献
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C. Colinet 《Intermetallics》2003,11(11-12):1095
A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described. 相似文献
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洋务派在洋务学堂的办学活动中,为了解决西学专业学科的教学困难,采用了聘请外籍教师的应急措施.他们以真才实学,合同制管理作为主导思想,并认为这种解决师资的途径只是权宜之计,并非久远.从客观上看,洋务派的教师聘任思想有深刻的历史影响. 相似文献
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扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性. 相似文献
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论述了CAD技术中参数化设计的三种建模方法,重点介绍了基于特征的参数化建模原理。在此基础上,分析机械设计中的机构结构,归纳出其零件的几何特征构成。设计了机构CAD图形库,并提出了该图形库生成步骤和人机交互界面。 相似文献