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采用曲面柔性轧制方法可以实现三维曲面板类件的连续、柔性成形,为了验证该方法的可行性,本文基于曲面柔性轧制原理,设计出成形装置并研究了装置关键部件工作辊的驱动方式,驱动方式可以分为单端与双端两种;进行相关成形实验并对曲面柔性轧制成形工艺进行了分析,探讨了成形过程.结果表明:一次调形成形工艺适用于小变形量情况,成形质量好,效率高;渐进调形成形工艺,以小的压下量逐渐使板料成形,在一定程度上可以消除板料边缘皱褶,减小回弹,利于板料成形;理论上讨论了实时调形成形工艺,该种工艺将会提高成形自动化与效率.对成形件进行了成形精度与厚度分布研究,表明成形效果良好,验证了曲面柔性轧制成形方法的可行性与实用性. 相似文献
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目的对比研究力-位移分控多点弯曲成形的受力和变形特点,揭示力-位移分控多点成形技术改善成形质量的机理。方法首先设计制造出采用力-位移分控多点成形原理成形的实验装置,并进行圆柱面的实际成形,比较不同成形模式下所获得成形制件的差异,然后采用理论分析和数值模拟等手段,分析对比不同成形模式的受力与变形条件,探讨不同成形模式下的变形特点与规律。结果从理论上给出了力-位移分控多点成形能有效减小回弹、消除\"直边效应\"的力学原理,指出了力-位移分控多点成形技术减小回弹的根本原因在于法向约束力的作用,且回弹减小量与法向约束力的大小成正比,并通过数值模拟,从应力和应变分布、支反力变化等方面予以了验证。结论力-位移分控多点成形从本质上改变了板材的受力和变形条件,能有效提升成形质量。 相似文献
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多点成形中回弹量的测量与控制方法研究 总被引:3,自引:0,他引:3
针对多点成形中工件的回弹问题,提出了一种测量和控制回弹的新方法.回弹量的测量方面,采用自行研制的非接触式三维激光扫描装置测量工件表面的三维点云信息;对不在同一坐标系下的测量数据和目标模型数据,用两步配准方法进行全局优化配准,克服了配准过程中常见的局部极小问题;采用改进的Shepard插值函数为初始曲面模型,用基于高斯曲率的采样型值点拟合出NURBS曲面.通过上述步骤快速、准确地计算出回弹量,改变了传统的利用靠模测量回弹量的方法.回弹控制方面,用测量的回弹量试验数据建立BP神经网络回弹预测模型,根据预测量调整基本体群的工具曲面形状,经过多次预测和基本体曲面形状的修改,最终实现控制回弹的目的.通过实例表明,上述方法可行,回弹量可控制到允许的精度. 相似文献
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为提高金属板材渐进成形的成形质量、成形精度、成形效率和成形极限,了解不同渐进成形工艺对制件成形性能的影响,本文以典型方锥台制件为研究对象,利用有限元软件MSC.Marc对2种渐进成形工艺进行了三维建模,对比分析了单点渐进成形和多点复合渐进成形对制件等效塑性应变、厚度分布和成形精度的影响.数值模拟结果表明:单点渐进成形的等效塑性应变和厚度减薄主要集中在制件相邻侧壁间的拐角处,而多点复合渐进成形的等效塑性应变和厚度减薄均匀地分布在制件成形区;相同成形工艺参数下,相比单点渐进成形,多点复合渐进成形更有利于制件的成形效率、成形质量、成形精度和成形极限的提高,更有利于抑制破裂等失稳现象的产生.2种渐进成形工艺的成形试验表明,数值模拟结果与试验相符. 相似文献
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基于有限元数值模拟的工艺分析方法能提高橡皮成形工艺的零件质量,其中回弹预测的精度是橡皮成形数值模拟的关键。文章以有限元软件ANSYS为平台,针对飞机前缘蒙皮铝合金板2B06-T3,建立成形与回弹过程的数值模型,研究影响数值模拟回弹预测精度的关键因素,如单元积分类型、网格尺寸、接触与摩擦。提高数值模拟成形精度,需要精确控制模拟过程的关键环节,力求在每个环节减小误差累积。该文对实际生产具有指导意义。 相似文献
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本文比较了三种不同方法测得的柔性石墨压缩率和回弹率结果,并研究了密度、膨化倍率、粒度和纯度对压缩回弹性能的影响. 相似文献
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A novel idea to form three-dimensional (3D) sheet metal parts using three bendable rollers is presented. It can realize a continuous flexible forming of sheet metal. The forming principle is introduced and forming equipment with three bendable rollers has been developed. The bendable roller with shape-adjusting device is designed based on a flexible shaft of steel wires. Some experiments were performed and typical 3D surface parts were formed. The experiments show that the transversal spine of 3D part is determined by the bended shape of the bendable rollers, and the longitudinal spine of the 3D part is determined by the relative displacement among the top roller and the two bottom rollers. The technology of forming 3D surface sheet metal using bendable rollers can produce 3D surface parts in a rapid and economical way. 相似文献
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《Materials Science & Technology》2013,29(9):1139-1143
AbstractIn order to improve the mechanical properties and reduce fabrication cost of large sheet metal parts, creep age forming (CAF) technology was developed, which is a process combined creep forming and heat treatment together. Springback of the workpiece in CAF is directly related to process parameters, such as, aging time, experimental stress and temperature. The aim of this paper is to establish a set of creep constitutive model, which can accurately predict the springback of 2124 aluminium alloy in CAF. A series of creep tests were carried out under different stress levels as 200, 225 and 250 MPa, and different temperatures as 185, 190 and 195°C for the solid solution treated and quenched 2124 aluminium alloy. Based on creep test data, a set of classic creep constitutive equations were established. Some important conclusions were drawn: the fitting curves of the constitutive equations could describe the test data in a good way; the creep strain increases with the increasing aging time, temperature and experimental stress. Then the springback of 2124 aluminium alloy during CAF process were analyzed by the finite element software MSC.Marc. Comparisons between the experiment analyses and finite element models show good correlation, and approve the forecast capability of FEM simulation for springback after CAF. At the end, the influence of process parameters on springback is studied, which provides essential foundation for designer to evaluate scheme and to optimise tool system design. 相似文献
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通过实例对工件表面微观结构的三维测量技术进行了系统描述,并重点介绍激光造型新工艺以及成型表面的特点,提出"三维评价"法来检验、评定经激光造型后形成的新表面,以替代传统的二维检测方法。另外介绍最近的"自动变焦形貌测量"新技术,可进一步提高检测自动化程度,大大提高检测工作效率。 相似文献
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R. A. Lingbeek W. Gan R. H. Wagoner T. Meinders J. Weiher 《International Journal of Material Forming》2008,1(3):159-168
Now that Finite Element springback prediction has become possible, springback compensation can also be carried out in the context of a forming simulation, before actual production tools are made. The Displacement Adjustment (DA) and Springforward (SF) methods were applied to an analytical bar stretch-bending model, in order to gain insight about the influence of material, process and geometrical parameters on springback and compensation. The DA method was investigated in both a one-step and iterative variant. In one-step DA, a compensation factor is required. This factor can be directly calculated for the analytical model. The results can be used as a guideline for industrial processes, where such a calculation is not possible. Finally, it was shown that iterative DA leads to better tool shapes than SF, and that practical and computational problems make the use of SF impossible in an industrial context. 相似文献
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By adoption of double-device systems, integral imaging can be enhanced in image depth, viewing angle, or image size. Theoretical analyses are done for the double-image-plane integral imaging systems. Both ray optics analysis and wave optics analysis confirm that the double-device integral imaging systems can pick up and display images at two separate image planes. The analysis results are also valuable in the understanding of the conventional integral imaging systems for image positions off the central depth plane. 相似文献
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The work reported in the present paper constitutes a part of a project on simulation of springback in sheet metal forming. Previous work in this project has been concentrated on material modeling and characterization with focus on springback applications. It has been demonstrated that, with proper considerations of all aspects of the material model and the material properties, excellent springback results can be obtained for simple problems. At the simulation of real, industrial parts, a number of additional problems are encountered. Many of these problems are associated with deviations from nominal geometries and other properties. These are examples of factors that influence the outcome of the forming process, but are unknown to the analyst, and can therefore not be considered in the simulation of the forming process. Other phenomena are known to exist, but due to their complexity, they are practically impossible to consider in industrial simulations. Examples of such phenomena are the true frictional behavior in contacts between the blank and the tools, and the flexibility of the press and the forming tool. The influence of these kinds of effects is discussed in the present paper. In the current study, a semi-industrial tool, specially designed to catch those springback problems that are encountered in the forming of real industrial, parts, is used. The tool includes several characteristics that can be found in typical forming tools, such as several draw radius steps and change-over in section geometries. Effects like flange/wall angle changes, sidewall curl and twist are obtained at springback. The sensitivity of the predicted springback is evaluated with respect to various numerical factors, such as the friction coefficient, the material model, and the mesh density. Finally, the quality of the predicted springback behavior for four different materials, commonly used in the automotive industry, is evaluated. 相似文献
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Giovanni Mimmi Carlo Rottenbacher Giovanni Bonandrini 《International Journal of Mechanics and Materials in Design》2009,5(1):61-77
In this paper, the motion input pre-shaping, applied to flexible manipulators for space applications, is analyzed in terms of sensitivity and robustness to parameters uncertainties. The special environment of space operations and the project specifications lead to the design of manipulators with light and flexible structures. In order to highlight the performances of these methods an open loop control technique is implemented. The control technique is verified by both numerical simulations and experiments. This paper presents the experimental set-up and the results of a series of experimental tests carried out on the space robot simulator assembly, called test-bed for microgravity simulation in robotic arm dynamics (TeMSRAD). The innovative task of the research is to determine experimentally the sensitivity curve for one-hump and two-hump extra-insensitive input shapers, for different vibration limits, by purposely introducing errors in the system model, in order to simulate typical operating conditions. Paper was presented at M2D’2006, 5th International Conference on Mechanics and Materials in Design, Porto, Portugal, 24–26 July 2006. 相似文献
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多点成形是一种先进的制造技术,但其成形特点与传统的冲压成形方式相比具有很大差别.本文采用有限元数值模拟手段针对多点成形过程中产生的压痕现象以及消除压痕的措施进行探讨,主要是对比多点模具成形和多点压机成形两种不同工艺,分析不同成形工艺条件下对压痕的影响.本文用显式动力学软件对1mm与3mm厚度的马鞍型曲面件进行数值模拟,结果表明,在相同条件下,用多点模具工艺成形的板材比用多点压机工艺成形的板材压痕深度大3-15倍,而且在成形过程中出现压痕的时间早.多点压机成形方式比多点模具成形方式具有成形效果好,缺陷少(可以减小或消除压痕和起皱等缺陷),并且有利于板材的流动,能够得到更大的变形量. 相似文献
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Dependences are constructed for calculating short-time strength and probability of failure of ceramic parts loaded (under different conditions) successively with constant test and operating loads of differing durations. These dependences are based on the concepts that durability of the ceramic is determined by the time of growth in critical defects. Using these dependences, an expression which accounts for depletion in safe life of the ceramic during the proof tests is obtained for the probability of failure of a tested part during operation. It is suggested that the test load for the proof test be determined by minimizing the probability of failure of proof tested ceramic parts.Translated from Problemy Prochnosti, No. 10, pp. 58–61, October, 1991. 相似文献
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针对板件初始毛坯形状计算以及正交异性板的快速有限元分析问题,依据拉深件的UG模型,导出了零件的三角网格数据,并采用几何映射方法得到了用于快速有限元分析的拉深件初始展开毛坯.在此基础上,基于理想变形假设以及Hill’48正交异性屈服准则,给出了用于拉深件成形过程快速分析的一步法数学公式和有限元表达,并在Unigraphics系统中进行了有限元分析的后置处理.此外,对TC1钛板筒型拉深件毛坯初始形状进行了优化,并对成形中拉深件厚向应变分布进行了分析,得到了满意结果. 相似文献