共查询到20条相似文献,搜索用时 171 毫秒
1.
2.
3.
针对整体机械加工成形的新型桥塞金属密封件在坐封后密封面出现裂纹缺陷的现象展开了研究。通过坐封过程力学分析和不同状态下组织形貌观察,得出产生裂纹的原因。在此基础上,提出金属密封件的液压成形工艺。采用数值模拟完成液压成形模具和工艺参数的优化设计,并进行密封件的液压成形试验和坐封试验。试验结果表明,液压成形工艺设置成形压力为180MPa、保压时间为5s时,所得金属密封件表面质量较好,坐封后不产生裂纹。液压成形金属密封件密封面不同状态下的组织形貌观测和液压成形过程中的受力分析进一步表明,液压成形过程中的径向压应力能够改善晶界开裂等现象,因此与整体机械加工成形的密封件相比,液压成形工艺可以明显改善坐封效果。 相似文献
4.
介绍了管材液压成形工艺,根据液压成形原理,自主研制出具备高压发生器、阀门管路等配件的超高压液压系统,同时通过可编程控制器实现对电磁元件的控制,有效地解决了管材在液压成形过程中的端口密封、进给补料等关键问题,为管材液压成形的实验研究奠定了基础。 相似文献
5.
6.
双金属薄壁管冲击液压胀形技术是在液压胀形与冲压成形基础上发展起来的一种复合成形技术。冲击液压载荷作用下的双金属薄壁管成形所需内压力源自于管坯型腔体积的压缩,其大小随液体体积压缩量变化而变化,为此提出了基于冲击液压载荷作用下双金属薄壁管的内压力形成机理的研究。首先介绍了双金属薄壁管冲击液压胀形的成形原理;然后,通过对内外管轴向冲击液压预成形与径向冲击液压成形过程中内压力形成的理论分析,构建了管坯型腔内压力与体积变化之间的数学模型;同时,利用Ansys Workbench有限元模拟技术获得了内外管轴向冲击液压预成形与径向冲击液压成形过程的内压力,通过有限元模拟与理论分析结果的对比发现,两者具有较好的一致性,并通过模型误差优化了内压力数学模型,为双金属薄壁管冲击液压胀形技术的进一步研究奠定了良好的理论与应用基础。 相似文献
7.
8.
9.
10.
11.
管材液压成形技术是一个相对新颖的技术,其在应用过程中仍然有许多问题需要研究和解决。基于有限元法的管材液压成形数值模拟技术发展的时间更短,有待进一步研究和发展。针对这种发展要求,提出了管材液压成形数值模拟中分析模型的构造方法,并且重点介绍了逆向构造中管件中心轴线的抽取算法即边界递进搜寻法,这个算法不仅运行速度快,实现简单,而且具有较强的适应性。 相似文献
12.
管材液压成形技术是一个相对新颖的技术,其在应用过程中仍然有许多问题需要研究和解决。基于有限元法的管材液压成形数值模拟技术发展的时间更短,有待进一步研究和发展。针对这种发展要求,提出了管材液压成形数值模拟中分析模型的构造方法,并且重点介绍了逆向构造中管件中心轴线的抽取算法即边界递进搜寻法,这个算法不仅运行速度快,实现简单,而且具有较强的适应性。 相似文献
13.
Mikhail Sorine Isadora van Riemsdijk 《International Journal of Mechanical Sciences》2008,50(9):1411-1422
This article studies tubular hydroforming of high strength low alloy (HSLA) and dual phase (DP600) straight tubes under the action of end feeding loads. Experiments demonstrate that higher end feed loads enhance the formability of the tubes and increase the internal fluid pressure for onset of necking and bursting. Because of the action of the internal pressure and the axial compressive load, the onset of localization (necking) is due to a complex three-dimensional state of stress. Using free expansion experiments, approximate upper and lower bound strain-based forming limit curves are determined for the tube materials. These limit curves, in turn, are used to derive upper and lower bound extended stress-based forming limit curves [Simha et al., Prediction of necking in tubular hydroforming using an extended stress-based FLC. Transactions of the ASME Journal of Engineering Materials and Technology 2007;129(1): 36-47]. In conjunction with finite element computations that use solid elements to model the tube, these stress-based limit curves are used to predict upper and lower bound necking pressures under the action of end feed loading. These predictions of necking pressures, when an appropriate coefficient of tube-die friction is used, are found to bracket the experimentally measured necking pressures. Computations using plane stress shell elements to model the tubes are shown to give erroneous results, since the plane stress approximation is not valid when tubes are hydroformed in a die. 相似文献
14.
分析了液压成形设备的组成以及在研发波动加载管材液压成形系统过程中涉及的关键问题,并对每个问题都提出了合理的解决方案,实现了系统的设计要求。 相似文献
15.
B. Yang W. G. Zhang S. H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5-6):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
16.
B. Yang W.G. Zhang S.H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
17.
提出改进液压成型工艺,并通过Dynaform软件仿真及实际生产验证。该方法舍弃了通常管材液压成形中所需的超高压供给系统以及平衡冲头,进而大大降低设备费用。在验证工艺正确基础上,通过Dynaform软件仿真分析影响三通管液压成型因素。仿真模拟分析为模具设计方案和液压成形工艺方案设计提供了科学的依据,提高了设计效率。 相似文献
18.
为明晰焊管内高压成形焊缝的合理有限元建模方式,针对激光焊接接头的材料性能分布特点提出三种焊缝建模方式,分别为完整焊缝模型、粗略焊缝模型和无焊缝模型。通过与试验结果对比,从壁厚分布和几何形状两方面,分析不同焊缝简化方式对送料区、过渡区和胀形区模拟精度的影响情况。指出焊缝对模拟精度有影响,受影响区域不超过3倍焊缝宽度。只有建立焊缝模型才能模拟出靠近焊缝部位壁厚过渡减薄的变形特征,但建立完整焊缝模型和建立粗略焊缝模型的模拟精度相差不大,最大误差均小于6.5%。在综合考虑误差大小和典型变形特征模拟准确性后,给出适合激光焊管内高压成形的焊缝有限元建模方式。 相似文献
19.
A. Fatemi M. R. Morovvati F. R. Biglari 《The International Journal of Advanced Manufacturing Technology》2013,68(1-4):263-276
In this paper, the influence of tube material, microstructure, and heat treatment on process responses of tube hydroforming has been studied. One of the most important parameters in performing a successful tube hydroforming process is the selection of appropriate material for tubes. In the analysis section, effective parameters for the selection of an appropriate tube material for the hydroforming process have been investigated; it was concluded that higher strain hardening exponent (n), elasticity modulus (E), and anisotropy index (R) can enhance formability in this process; and the effects of microstructure and heat treatment on the formability of ASTM C11000 copper and ASTM AA1050 aluminum have been investigated. Consequently, four different heat treatment processes, which had different heating temperatures and durations, were selected, in addition to different cooling methods for each of the materials. In the experimental tests, the effects of these heat treatment methods on maximum bulging height, thickness strains, and final forming pressures were scrutinized. The effects of heat treatment on copper microstructure were also studied through metallographic tests; on the other hand, the effects of microstructure on tube hydroforming process were justified. As a result of these analyses, two heat treatment methods, namely, heating to 450 and 350 °C for 15 min and cooling in water, were recommended for copper and aluminum, respectively. Using these methods and due to their consequent fine and homogenous microstructure, higher mechanical strength and increase in material formability was achieved by attaining higher thickness strain and bulging height values. Finally, after extracting the mechanical properties of the two materials and comparing them with each other, parameters of strength coefficient and strain hardening exponent were reported as two effective factors that would improve tube deformation by tube hydroforming process. 相似文献
20.
M. Kadkhodayan A. Erfani-Moghadam 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):73-85
This paper proposes a new method to design the optimal load curves for hydroforming T-shaped tubular parts. In order to assess the mathematical models, a combination of design of experiment and finite element simulation was used. The optimum set of loading variables was obtained by embedding the mathematical models for tube formability indicators into a simulated annealing algorithm. The adequacy of the optimum results was evaluated by genetic algorithm. Using this method, the effect of all loading paths was considered in hydroforming of T-shaped tubes. Eliminating of variables with lower effect could simplify the problem and help designers to study the effect of other parameters such as geometrical conditions and loading parameters. Applying the optimal load paths obtained with the proposed method caused an improvement in the thickness distribution in the part as well as a decrease in maximum pressure. 相似文献